"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:28bd0834-5fbc-4af4-b7fe-bb790c76bebb","http://resolver.tudelft.nl/uuid:28bd0834-5fbc-4af4-b7fe-bb790c76bebb","Transforming Zeolite Tuff and Cigarette Waste into Eco-Friendly Ceramic Bricks for Sustainable Construction","Ibrahim, Jamal Eldin F.M. (University of Miskolc); Basyooni, Mohamed A. (TU Delft Dynamics of Micro and Nano Systems; Selçuk University; National Research Institute of Astronomy and Geophysics); Móricz, Ferenc (University of Miskolc); Kocserha, István (University of Miskolc)","","2024","The use of waste materials has gained attention as a sustainable approach in various industries. Cigarette waste, which is typically discarded as a non-recyclable material, poses a significant environmental challenge due to its toxicity and slow decomposition rate. However, by incorporating this waste into ceramic bricks, new approaches for waste management and resource utilization are explored. This research work provides a detailed evaluation of the possibility of utilizing natural zeolite tuff incorporated with cigarette waste to produce sustainable ceramic bricks. Uniform powders are produced by milling various combinations of zeolitic tuff and cigarette waste using a planetary ball mill. The substitution ratios ranged from 0% to 12% by weight of the zeolitic tuff, with increments of 2%. Ceramic discs were formed by dry pressing and then subjected to sintering at different heat treatment temperatures (950–1250 °C). The impact of the inclusion of cigarette waste on the microstructural and technical features of zeolite tuff-based ceramic bricks has been thoroughly investigated. The results of the experiments demonstrate that incorporating cigarette waste into the development of ceramic bricks leads to improved thermal insulation properties, with thermal conductivity ranging from 0.33 to 0.93 W/m·K. Additionally, these bricks exhibit a lighter weight in a range of 1.45 to 1.96 g/cm3. Although the inclusion of cigarette waste slightly reduces the compressive strength, with values ranging from 6.96 to 58.6 MPa, it still falls within the acceptable range specified by standards. The inclusion of cigarette waste into zeolite tuff is an innovative approach and sustainable practice for reducing energy consumption in buildings while simultaneously addressing the issue of waste disposal and pollution mitigation.","zeolite tuff; cigarette waste; dry compaction; thermal conductivity; compressive strength","en","journal article","","","","","","","","","","","Dynamics of Micro and Nano Systems","","",""
"uuid:49b6f6d6-dfa8-4af5-8c72-36cc0990a8d6","http://resolver.tudelft.nl/uuid:49b6f6d6-dfa8-4af5-8c72-36cc0990a8d6","Investigation of petrophysical and hydrogeological parameters of the transboundary Nubian Aquifer system using geophysical methods","Mohammed, Musaab A. A. (University of Miskolc; University of Bahri); Mohamed, Ahmed (Assiut University); Szabó, Norbert P. (University of Miskolc); Alarifi, Saad S. (King Saud University); Abdelrady, Ahmed (TU Delft Water Resources); Alao, Joseph Omeiza (Air Force Institute of Technology)","","2024","The recent research aims to investigate the petrophysical and hydrogeological parameters of the Nubian aquifer system (NAS) in Northern Khartoum State, Sudan, using integrated geophysical methods, including surface electrical resistivity and geophysical well-logging. The Nubian aquifer is a transboundary regional aquifer that covers vast areas in Sudan, Egypt, Libya and Chad. The well-logs, including self-potential (SP), natural gamma ray (GR), and long normal resistivity (RS), are integrated with Vertical Electrical Sounding (VES) measurements to delineate the hydrostratigraphical units. As a result, two aquifers are detected. An upper aquifer comprises coarse sand with an average thickness of 50 m and a lower aquifer of sandstone with more than 200 m thickness. For a thorough evaluation of the aquifers, in the first stage, the petrophysical and hydrogeological parameters, including formation factor, total and effective porosity, shale volume, hydraulic conductivity, and transmissivity, are measured solely from geophysical well-logs. In the second step, the results of geophysical well logs are combined with VES and pumping test data to detect the spatial variation of the measured parameters over the study area. As a result, the hydraulic conductivity of the Nubian aquifers ranged from 1.9 to 7.8 m/day, while the transmissivity varied between 120 and 733 m2/day. These results indicated that the potentiality of the Nubian formation is high; however, in some regions, due to the sediment heterogeneity, the aquifers have intermediate to high potential. According to the obtained results, it can be concluded that the Nubian Aquifer in Khartoum state is ideal for groundwater development. This research discovered that geophysical approaches can be used to characterize moderately heterogeneous groundwater systems by comparing the Nubian aquifer with similar aquifer systems that have similar hydrogeological settings. This study emphasized the application of universal principles in extrapolating hydraulic parameters in hydrogeophysical surveys. This approach aims to reduce the costs and efforts associated with traditional hydrogeological approaches.","well logs; vertical electrical sounding; pumping test; hydraulic conductivity; transmissivity","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:0a950056-8081-48e7-ad1f-117eeb2066f6","http://resolver.tudelft.nl/uuid:0a950056-8081-48e7-ad1f-117eeb2066f6","Screening of representative rainfall event series for long-term hydrological performance evaluation of grassed swales","Yang, F. (TU Delft Hydraulic Structures and Flood Risk; Southeast University); Fu, Dafang (Southeast University); Zevenbergen, C. (TU Delft Urban Design); Boogaard, Floris C. (Hanze Hogeschool Groningen; Deltares); Singh, Rajendra Prasad (Southeast University)","","2024","Evaluation of the hydrological performance of grassed swales usually needs long-term monitoring data. At present, suitable techniques for simulating the hydrological performance using limited monitoring data are not available. Therefore, current study aims to investigate the relationship between saturated hydraulic conductivity (Ks) fitting results and rainfall characteristics of various events series length. Data from a full-scale grassed swale (Enschede, the Netherlands) were utilized as long-term rainfall event series length (95 rainfall events) on the fitting outcomes. Short-term rainfall event series were extracted from these long-term series and used as input in fitting into a multivariate nonlinear model between Ks and its influencing rainfall indicators (antecedent dry days, temperature, rainfall, rainfall duration, total rainfall, and seasonal factor (spring, summer, autumn, and winter, herein refer as 1, 2, 3, and 4). Comparison of short-term and long-term rainfall event series fitting results allowed to obtain a representative short-term series that leads to similar results with those using long-term series. A cluster analysis was conducted based on the fitting results of the representative rainfall event series with their rainfall event characteristics using average values of influencing rainfall indicators. The seasonal index (average value of seasonal factors) was found to be the most representative short rainfall event series indicator. Furthermore, a Bayesian network was proposed in the current study to predict if a given short-term rainfall event series is representative. It was validated by a data series (58 rainfall events) from another full-scale grassed swale located in Utrecht, the Netherlands. Results revealed that it is quite promising and useful to evaluate the representativeness of short-term rainfall event series used for long-term hydrological performance evaluation of grassed swales. Graphical Abstract: (Figure presented.).","Bayesian network; Grassed swale; Long-term hydrological performance; Rainfall event series; Representativeness; Saturated hydraulic conductivity","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-08-23","","","Hydraulic Structures and Flood Risk","","",""
"uuid:e41eda02-200e-4cdb-9f08-66f4043e4bfe","http://resolver.tudelft.nl/uuid:e41eda02-200e-4cdb-9f08-66f4043e4bfe","Market-orientated solutions to increase thermal conductivity in latent thermal energy storage systems","Righetti, Giulia (Università degli Studi di Padova); Zilio, Claudio (Università degli Studi di Padova); Hooman, K. (TU Delft Heat Transformation Technology); Mancin, Simone (Università degli Studi di Padova)","","2024","Among experts, it is well-known that the thermal conductivity of PCMs (phase change materials) is low hence a major limitation for their commercial application. This work proposes alternative, inexpensive, but nevertheless effective solutions to increase the average thermal conductivity of a PCM system (a commercial paraffin wax, having a phase change temperature of about 40 °C) used for thermal energy storage. 600 g of PCM fills an annulus wrapping an inner tube used to either charge or discharge heat to the PCM. The effect of the flow rate and temperature of the water used as heat transfer fluid was experimentally analysed. The flow rate was set to vary between 2 and 8 l min-1 and the temperature between 45 and 55 °C. We tested three different aluminum-based thermal enhancers: a commercially available metal foam sample, a wire mesh, and irregular flakes (chips) obtained as waste product of machining operations. The PCM-only sample exhibited the longest charging and discharging times, while the PCM + foam sample shortened them the most. The two cost-effective solutions (chip and wire mesh) resulted in intermediate phase change times. A performance indicator, in terms of cost per phase change rate, is proposed to compare different enhancers. It demonstrated that these two cost-effective thermal conductivity enhancing solutions can become a key enabling method to widely deploy latent thermal energy technology widely in many different applications.","Economic solution; Latent thermal energy storage; Metallic chip; Metallic foam; PCM; Thermal conductivity","en","journal article","","","","","","","","","","","Heat Transformation Technology","","",""
"uuid:e230fab5-afda-41f9-93cf-0ce8c6020f64","http://resolver.tudelft.nl/uuid:e230fab5-afda-41f9-93cf-0ce8c6020f64","The organo-metal-like nature of long-range conduction in cable bacteria","Pankratov, Dmitrii (Universiteit Antwerpen); Hidalgo Martinez, Silvia (Universiteit Antwerpen); Karman, Cheryl (Universiteit Antwerpen); Gerzhik, Anastasia (Forschungszentrum Jülich GmbH); Gomila, Gabriel (Barcelona Institute of Science and Technology (BIST); Universitat de Barcelona); Trashin, Stanislav (Universiteit Antwerpen); Boschker, H.T.S. (TU Delft BT/Environmental Biotechnology; Universiteit Antwerpen); Geelhoed, Jeanine S. (Universiteit Antwerpen); Meysman, F.J.R. (TU Delft BT/Environmental Biotechnology; Universiteit Antwerpen)","","2024","Cable bacteria are filamentous, multicellular microorganisms that display an exceptional form of biological electron transport across centimeter-scale distances. Currents are guided through a network of nickel-containing protein fibers within the cell envelope. Still, the mechanism of long-range conduction remains unresolved. Here, we characterize the conductance of the fiber network under dry and wet, physiologically relevant, conditions. Our data reveal that the fiber conductivity is high (median value: 27 S cm−1; range: 2 to 564 S cm−1), does not show any redox signature, has a low thermal activation energy (Ea = 69 ± 23 meV), and is not affected by humidity or the presence of ions. These features set the nickel-based conduction mechanism in cable bacteria apart from other known forms of biological electron transport. As such, conduction resembles that of an organic semi-metal with a high charge carrier density. Our observation that biochemistry can synthesize an organo-metal-like structure opens the way for novel bio-based electronic technologies.","Bioelectronics; Cable bacteria; Electrochemical impedance spectroscopy; Long-distance electron transport; Protein conductivity","en","journal article","","","","","","","","","","","BT/Environmental Biotechnology","","",""
"uuid:a097ae29-f9c3-4629-87f0-49c037cdec52","http://resolver.tudelft.nl/uuid:a097ae29-f9c3-4629-87f0-49c037cdec52","From Short Circuit to Completed Circuit: Conductive Hydrogel Facilitating Oral Wound Healing","Zhou, Qiangqiang (Fudan University); Dai, Hanqing (Fudan University); Yan, Yukun (Fudan University); Qin, Zhiming (Fudan University); Zhou, Mengqi (Fudan University); Zhang, Wanlu (Fudan University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Guo, Ruiqian (Fudan University); Wei, X. (Fudan University)","","2024","The primary challenges posed by oral mucosal diseases are their high incidence and the difficulty in managing symptoms. Inspired by the ability of bioelectricity to activate cells, accelerate metabolism, and enhance immunity, a conductive polyacrylamide/sodium alginate crosslinked hydrogel composite containing reduced graphene oxide (PAA-SA@rGO) is developed. This composite possesses antibacterial, anti-inflammatory, and antioxidant properties, serving as a bridge to turn the “short circuit” of the injured site into a “completed circuit,” thereby prompting fibroblasts in proximity to the wound site to secrete growth factors and expedite tissue regeneration. Simultaneously, the PAA-SA@rGO hydrogel effectively seals wounds to form a barrier, exhibits antibacterial and anti-inflammatory properties, and prevents foreign bacterial invasion. As the electric field of the wound is rebuilt and repaired by the PAA-SA@rGO hydrogel, a 5 × 5 mm2 wound in the full-thickness buccal mucosa of rats can be expeditiously mended within mere 7 days. The theoretical calculations indicate that the PAA-SA@rGO hydrogel can aggregate and express SOX2, PITX1, and PITX2 at the wound site, which has a promoting effect on rapid wound healing. Importantly, this PAA-SA@rGO hydrogel has a fast curative effect and only needs to be applied for the first three days, which significantly improves patient satisfaction during treatment.","conductive hydrogel; microphysiological electric field; oral mucosal disease; tissue regeneration","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-08-02","","","Electronic Components, Technology and Materials","","",""
"uuid:64ae1a0e-9e13-4ba9-a2ed-b61eafce12c6","http://resolver.tudelft.nl/uuid:64ae1a0e-9e13-4ba9-a2ed-b61eafce12c6","Identification of Atrial Transmural Conduction Inhomogeneity Using Unipolar Electrogram Morphology","Zhang, Lu (Erasmus MC); van Schie, M.S. (Erasmus MC); Xiang, Hongxian (Erasmus MC); Liao, Rongheng (Erasmus MC); Zheng, Jiahao (Erasmus MC); Knops, Paul (Erasmus MC); Taverne, Yannick J.H.J. (Erasmus MC); de Groot, N.M.S. (TU Delft Signal Processing Systems; Erasmus MC)","","2024","(1) Background: Structural remodeling plays an important role in the pathophysiology of atrial fibrillation (AF). It is likely that structural remodeling occurs transmurally, giving rise to electrical endo-epicardial asynchrony (EEA). Recent studies have suggested that areas of EEA may be suitable targets for ablation therapy of AF. We hypothesized that the degree of EEA is more pronounced in areas of transmural conduction block (T-CB) than single-sided CB (SS-CB). This study examined the degree to which SS-CB and T-CB enhance EEA and which specific unipolar potential morphology parameters are predictive for SS-CB or T-CB. (2) Methods: Simultaneous endo-epicardial mapping in the human right atrium was performed in 86 patients. Potential morphology parameters included unipolar potential voltages, low-voltage areas, potential complexity (long double and fractionated potentials: LDPs and FPs), and the duration of fractionation. (3) Results: EEA was mostly affected by the presence of T-CB areas. Lower potential voltages and more LDPs and FPs were observed in T-CB areas compared to SS-CB areas. (4) Conclusion: Areas of T-CB could be most accurately predicted by combining epicardial unipolar potential morphology parameters, including voltages, fractionation, and fractionation duration (AUC = 0.91). If transmural areas of CB indeed play a pivotal role in the pathophysiology of AF, they could theoretically be used as target sites for ablation.","electrograms; endo-epicardial delay; simultaneous endo-epicardial mapping; sinus rhythm; transmural conduction block","en","journal article","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:ab0d528e-a03c-4e14-8df1-538a959afb96","http://resolver.tudelft.nl/uuid:ab0d528e-a03c-4e14-8df1-538a959afb96","Experimental characterization of damage during geothermal production of hot dry rocks: Comprehensive effects of the damage-elastic deformation on conductivity evolution","Xu, Fuqiang (China University of Petroleum - Beijing); Shi, Yu (Southwest Jiaotong University); Song, Xianzhi (China University of Petroleum - Beijing); Wu, Wei (Nanyang Technological University); Song, G. (TU Delft Applied Geology); Li, Shuang (China University of Petroleum - Beijing)","","2024","The development of hot dry rocks (HDRs) is of great significance to adjusting energy structure, alleviating energy shortage, reducing pollution, etc. Low-permeability granite is the predominant rock type in deep HDRs, making fractures the primary pathways for fluid circulation and heat extraction. The production of HDRs is significantly influenced by variable fracture conductivity, but current conductivity characterization primarily relies on the elastic deformation of the matrix, neglecting the impact of damage. Accordingly, we propose an experimental method and a supporting apparatus, which is used to unveil the conductivity evolution characteristics resulting from the comprehensive effects of damage and elastic deformation. The experimental results demonstrate that when subjected to confining force squeezing inward, the fracture conductivity experiences varying degrees of decrease compared to its initial state before the experiment. By utilizing the conductivity evolution rate as the evaluation criterion and conducting grey correlation analysis, it has been determined that temperature exerts the most significant influence on the conductivity evolution, followed by injection flow, and lastly, confining pressure. Moreover, rock particle types and production cycles also have different degrees of effect. After considering the comprehensive effects of damage-elastic deformation at the field-scale, the damage has a positive effect on conductivity enhancement. Our study provides a new approach for the characterization of fracture conductivity evolution for deep geothermal projects.","Comprehensive effects; Conductivity evolution; Elastic deformation; Fracture damage; Hot dry rocks; Injection experiment","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-09-07","","","Applied Geology","","",""
"uuid:dd3bff55-b684-47cc-96f3-6ff109d345a0","http://resolver.tudelft.nl/uuid:dd3bff55-b684-47cc-96f3-6ff109d345a0","Analysis of thermoplastic composites and conduction welded joints","Tijs, B.H.A.H. (TU Delft Aerospace Structures & Computational Mechanics)","Bisagni, C. (promotor); Turon Travesa, A. (promotor); Delft University of Technology (degree granting institution)","2023","Thermoplastic composites enable new manufacturing techniques such as conduction welding to make the aviation industry more sustainable, while at the same time, provide great benefits to cost-efficient high-volume production. One of the benefits of welding is that it reduces the amount of mechanical fasteners required. Fastener-free joining also poses new challenges, because the performance of these highly loaded structural joints relies heavily on the performance of the thermoplastic polymer matrix. Furthermore, there is currently not much understanding of the mechanisms involved in thermoplastic welded joint failure, and the numerical and experimental methodologies, originally developed and validated on thermoset composites, have not yet been fully assessed for thermoplastic composites. On top of that, the process conditions to manufacture these new structures may have a significant influence on the mechanical performance of the material and can thus play an important role in the design of thermoplastic composite structures.
The objective of this research is to analyse matrix dominated failure of thermoplastic composites and conduction welded joints and to develop both experimental and numerical methodologies to support the design of thermoplastic composites structures. The research addresses important linkages between the three main pillars of Manufacturing, Experimental and Numerical analysis....","Thermoplastic composites; conduction welding; virtual testing; continuum damage model; cohesive zone model; interlaminar; fracture toughness; fiber-bridging; characterization","en","doctoral thesis","","978-94-6473-101-9","","","","","","","","","Aerospace Structures & Computational Mechanics","","",""
"uuid:291baefe-c4b9-46ea-b250-a6c8f4e6ece8","http://resolver.tudelft.nl/uuid:291baefe-c4b9-46ea-b250-a6c8f4e6ece8","Pressure-assisted CU sintering for SiC Die-attachment application","Liu, X. (TU Delft Electronic Components, Technology and Materials)","Zhang, Kouchi (promotor); Ye, H. (copromotor); Microelectronics (degree granting institution); Delft University of Technology (degree granting institution)","2023","","nano Cu sintering; Silicon carbide power electronics packaging; Shear Strength; Mechanical reliability; Thermal conductivity; Molecular dynamics; Static and dynamic test; Nanoindentation","en","doctoral thesis","","978-94-6473-018-0","","","","","","2025-01-30","","","Electronic Components, Technology and Materials","","",""
"uuid:71dec77a-bb95-4e9a-86bd-3b39d620d29f","http://resolver.tudelft.nl/uuid:71dec77a-bb95-4e9a-86bd-3b39d620d29f","Accurate and Energy-Efficient Bit-Slicing for RRAM-Based Neural Networks","Diware, S.S. (TU Delft Computer Engineering); Singh, A. (TU Delft Computer Engineering); Gebregiorgis, A.B. (TU Delft Computer Engineering); Joshi, Rajiv V. (IBM Thomas J. Watson Research Centre); Hamdioui, S. (TU Delft Quantum & Computer Engineering); Bishnoi, R.K. (TU Delft Computer Engineering)","","2023","Computation-in-memory (CIM) paradigm leverages emerging memory technologies such as resistive random access memories (RRAMs) to process the data within the memory itself. This alleviates the memory-processor bottleneck resulting in much higher hardware efficiency compared to von-Neumann architecture-based conventional hardware. Hence, CIM becomes an attractive alternative for applications like neural networks which require a huge number of data transfer operations in conventional hardware. CIM-based neural networks typically employ bit-slicing scheme which represents a single neural weight using multiple RRAM devices (called slices) to meet the high bit-precision demand. However, such neural networks suffer from significant accuracy degradation due to non-zero Gmin error where a zero weight in the neural network is represented by an RRAM device with a non-zero conductance. This paper proposes an unbalanced bit-slicing scheme to mitigate the impact of non-zero Gmin error. It achieves this by allocating appropriate sensing margins for different slices based on their binary positions. It also tunes the sensing margins to meet the demands of either high accuracy or energy-efficiency. The sensing margin allocation is supported by 2's complement arithmetic which further reduces the influence of non-zero Gmin error. Simulation results show that our proposed scheme achieves up to 7.3× accuracy and up to 7.8× correct operations per unit energy consumption compared to state-of-the-art.","Computation-in-memory; bit-slicing; neural networks; non-zero Gmin error; conductance variation; nonidealities","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-08-07","","Quantum & Computer Engineering","Computer Engineering","","",""
"uuid:33babda2-9bab-491c-a757-69aa8ea582f5","http://resolver.tudelft.nl/uuid:33babda2-9bab-491c-a757-69aa8ea582f5","Fabrication and Characterization of a Leaky Lens Photo-Conductive Antenna on Low Temperature Grown GaAs Membranes","Bueno Lopez, J. (TU Delft Electronics); Sberna, P.M. (TU Delft EKL Processing); Fiorellini Bernardis, A. (TU Delft Tera-Hertz Sensing); Zhang, H. (TU Delft Tera-Hertz Sensing); Neto, A. (TU Delft Tera-Hertz Sensing); Llombart, Nuria (TU Delft Tera-Hertz Sensing)","","2023","State-of-the-art THz pulsed commercial systems operating over large bandwidth suffer from high dispersion or low radiation efficiency due to the poor coupling between the transmitter and receiver photoconductive antennas (PCAs). In this work, we present the fabrication and characterization of a leaky-lens PCA that has the potential to solve this problem. The presented PCA is based on a low-temperature grown gallium arsenide (LT-GaAs) membrane with a 1:15 bandwidth coverage (0.1-1.5 THz), where the frequency response is constant. In order to fabricate the PCA on an LT-GaAs membrane, a novel fabrication process is developed. This process is dramatically faster than previously used processes (∼1.5 h instead of ∼20 h). Furthermore, an experimental validation of the radiated power together with the comparison to a standard bow-tie-based PCA fabricated on the same LT-GaAs wafer is shown in this article. We show that the PCA source on the LT-GaAs membrane is more efficient due to the enhanced leaky wave radiation. The leaky-lens PCA stands out as a great candidate to improve the coupling efficiency in THz pulsed commercial systems, where the maximum laser power that can be used is limited by the dispersion in the optic fiber.","leaky lens antenna; membrane-based micro-antenna; photo-conductive antenna; THz radiation; Time domain spectroscopy","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-03-05","","","Electronics","","",""
"uuid:a124953d-7e22-41af-9e72-e4c7f08ae9ff","http://resolver.tudelft.nl/uuid:a124953d-7e22-41af-9e72-e4c7f08ae9ff","A Thin-film Reconfigurable SiC Thermal Test Chip for Reliability Monitoring in Harsh Environments","Sattari, R. (TU Delft Electronic Components, Technology and Materials); van Zeijl, H.W. (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2023","Wide bandgap (WBG) semiconductor technologies enable significant progress in the emergence of power modules. Power cycling at elevated temperatures causes crack or delamination failure, especially at the die-attached bonded interface in the long term. Therefore, the in-situ reliability investigation of power modules, materials, and semiconductor packages is of great significance for modern industries. The silicon carbide's higher bandgap energy, intrinsic thermal conductivity, and mechanical strength make it a great candidate for the next generation of semiconductor, designed to operate in harsh conditions. In this study, a thin-film reconfigurable silicon carbide (SiC) thermal test chip (TTC) is designed and fabricated for reliability assessment in harsh environments. The proposed TTC realizes in-situ power/thermal cycling tests at elevated temperatures as well as characterization of novel materials such as nanoparticle-based sintering materials in die-attach technology and high-temperature-compatible epoxy molding compounds. The chip is equipped with thin-film platinum microheaters to realize modular power mappings, and platinum resistive temperature detectors (RTD) to examine the thermal reliability by monitoring the precise changes of the internal junction-to-case thermal resistance.","bandgap energy; die-attach; in-situ reliability investigation; junction-to-case thermal resistance; nanoparticle-based sintering; power cycling; power modules; resistive temperature detectors; thermal conductivity; Wide bandgap semiconductor technology","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-02-03","","","Electronic Components, Technology and Materials","","",""
"uuid:049cfba8-ca23-4da2-aca0-d169db8e15a5","http://resolver.tudelft.nl/uuid:049cfba8-ca23-4da2-aca0-d169db8e15a5","ThermoSurf: Thermal display technology for dynamic and multi-finger interactions","Peters, Luka (Student TU Delft); Serhat, Gokhan (Katholieke Universiteit Leuven); Vardar, Y. (TU Delft Human-Robot Interaction)","","2023","Thermal feedback has been proven to enhance user experience in human-machine interactions. Yet state-of-the-art thermal technology has focused on the single finger or palm in static contact, overlooking dynamic and multi-finger interactions. The underlying challenges include incompatible designs of conventional interfaces for providing salient thermal stimuli for such interactions and, thereby, a lack of knowledge on human thermal perception for relevant conditions. Here we present the ThermoSurf, a new thermal display technology that can deliver temperature patterns on a large interface suitable for dynamic and multi-finger interactions. We also investigate how user exploration affects the perception of the generated temperature distributions. Twenty-three human participants interacted with the device following three exploration conditions: static-single finger, dynamic-single finger, and static-multi finger. In these experiments, the individuals evaluated 15 temperature differences ranging from -7.5°C to +1.5°C with an initial temperature of 38°C. Our results showed that human sensitivity against thermal stimuli is significantly greater for static-single finger contact compared to the other tested conditions. In addition, this interaction type resulted in higher thermal discrimination thresholds than the ones reported in the literature. Our findings offer new perspectives on providing salient and consistent thermal feedback for future tactile interfaces.","Fingers; Heating systems; human thermal perception; human-machine interaction; Sensitivity; Skin; Temperature distribution; Temperature sensors; Thermal conductivity; thermal display; thermal feedback","en","journal article","","","","","","","","","","","Human-Robot Interaction","","",""
"uuid:0b035e0c-e9bd-43fb-93cd-db59f00cbc08","http://resolver.tudelft.nl/uuid:0b035e0c-e9bd-43fb-93cd-db59f00cbc08","Computational Fluid Dynamics Modeling of HIsarna Off-Gas System: Wall Modeling and Heat Loss Prediction","Hosseini, A. (TU Delft Team Yongxiang Yang); Calis, Randy (Tata Steel); van der Plas, Dirk (Tata Steel); Put, Pieter (Tata Steel); Agema, Jelle (Tata Steel); Meijer, Koen (Tata Steel); Hage, Johannes (Tata Steel); Offerman, S.E. (TU Delft Team Erik Offerman); Yang, Y. (TU Delft Team Yongxiang Yang)","","2023","The HIsarna off-gas system wall is a cooling jacket made of cooling pipes arranged in the radial direction and in a circular pattern. Part of the off-gas system cooling pipes are isolated using a low-thermal-conductivity refractory material to protect the cooling pipe from melting and thermal stresses. During long runs and due to thermomechanical stresses, the refractory material is lost, and its thickness is reduced. It is possible to measure the thickness of the refractory layer only during shutdown, which is a disadvantage during long runs. The aim is to investigate the possibility of predicting the thickness of the refractory material by using other parameters that are possible to measure during the operation. A combination of FEM and CFD modeling is used to develop a methodology for detailed wall modeling and refractory material loss prediction. Finite element method (FEM) analysis is used to obtain the thermal properties of the wall using detailed geometries for variable refractory thickness. The obtained properties are then used to build CFD models to study the effect of refractory thickness on wall heat loss, temperature and composition profiles. The proposed procedure is validated against the plant measurement, and according to the findings, it is possible to relate the wall thickness to measured parameters such as heat loss through the walls, temperature and carbon conversion.","computational fluid dynamics (CFD); finite element method (FEM); HIsarna; off-gas system; reflux chamber; heat transfer modeling; wall modeling; shell conduction modeling","en","journal article","","","","","","","","","","","Team Yongxiang Yang","","",""
"uuid:218dcad4-5334-4bf5-9f0e-2c59cf94d304","http://resolver.tudelft.nl/uuid:218dcad4-5334-4bf5-9f0e-2c59cf94d304","Effect of the Graphene Quantum Dot Content on the Thermal, Dynamic-Mechanical, and Morphological Properties of Epoxy Resin","Schneider, Bárbara (Mantova Indústria de Tubos Plásticos; Science and Technology of Rio Grande do Sul); Ornaghi Jr., Heitor Luiz (Science and Technology of Rio Grande do Sul); Monticeli, F.M. (TU Delft Structural Integrity & Composites); Romanzini, Daiane (Science and Technology of Rio Grande do Sul)","","2023","Different amounts of graphene quantum dots (CQDs) (0, 1, 2.5, and 5 wt%) were incorporated into an epoxy matrix. The thermal conductivity, density, morphology, and dynamic mechanical thermal (DMTA) properties were reused from the study of Seibert et al.. The Pearson plot showed a high correlation between mass loading, thermal conductivity, and thermal diffusivity. A poorer correlation with density and heat capacity was observed. At lower CQD concentrations (0.1 wt%), the fracture surface showed to be more heterogeneous, while at higher amounts (2.5 and 5 wt%), a more homogeneous surface was observed. The storage modulus values did not change with the CQD amount. But the extension of the glassy plateau increased with higher CQD contents, with an increase of ~40 °C for the 5 wt% compared to the 2.5 wt% and almost twice compared to the neat epoxy. This result is attributed to the intrinsic characteristics of the filler. Additionally, lower energy dissipation and a higher glass transition temperature were observed with the CQD amount. The novelty and importance are related to the fact that for more rigid matrices (corroborated with the literature), the mechanical properties did not change, because the polymer bridging mechanism was not present, in spite of the excellent CQD dispersion as well as the filler amount. On the other hand, thermal conductivity is directly related to particle size and dispersion.","carbon quantum dots; epoxy nanocomposite; thermal conductivity; structure and property relationship","en","journal article","","","","","","","","","","","Structural Integrity & Composites","","",""
"uuid:bfceaa04-f03c-4811-ae97-88b17723c48d","http://resolver.tudelft.nl/uuid:bfceaa04-f03c-4811-ae97-88b17723c48d","Dominant factors determining the hydraulic conductivity of sedimentary aquitards: A random forest approach","van Leer, Martijn D. (Universiteit Utrecht); Zaadnoordijk, Willem (TU Delft Water Resources; TNO); Zech, Alraune (Universiteit Utrecht); Buma, Jelle (TNO); Harting, Ronald (TNO); Bierkens, Marc F.P. (Universiteit Utrecht; Deltares); Griffioen, Jasper (Universiteit Utrecht; TNO)","","2023","Aquitards are common hydrogeological features and their hydraulic conductivity is an important property for various groundwater management issues. Predicting their hydraulic conductivity proves challenging, given its dependence on numerous variables. In this study, the dominant factors for predicting aquitard hydraulic conductivity are identified. To this end, a random forest model is trained on a dataset consisting of more than 1000 hydraulic conductivity measurements of core-scale sediment samples from a wide range of stratigraphic units and depths in the Netherlands. The dataset contains textural properties, such as the grain size distribution and porosity, as well as structural data, such as location, sampling depth, stratigraphical unit, lithofacies, organic carbon content, carbonate content and groundwater chloride concentration. Results show that clay fraction, stratigraphic unit, depth, lithofacies and x-coordinate are the most important features for predicting the hydraulic conductivity. Here, x-coordinate is presumably a proxy for distance from marine influence. Using a more detailed grain size distribution or using derived parameters such as the grain size percentiles does not improve the model any further. Our findings indicate that structural properties play a significant role in predicting aquitard conductivity, as they serve as indicators of processes such as compaction and soft-sediment deformation. The model is furthermore an effective method to estimate hydraulic conductivity for sediment samples without conducting costly and time-consuming hydraulic conductivity measurements.","Aquitards; Groundwater; Hydraulic conductivity; Machine learning; Parameterisation; the Netherlands","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:dfc86a37-1fd8-477d-a08d-ce504220f9d6","http://resolver.tudelft.nl/uuid:dfc86a37-1fd8-477d-a08d-ce504220f9d6","Estimation of Cardiac Fibre Direction Based on Activation Maps","de Vries, J.W. (TU Delft Signal Processing Systems); Sun, M. (TU Delft Signal Processing Systems); de Groot, N.M.S. (Erasmus MC); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2023","Estimating tissue conductivity parameters from electrograms (EGMs) could be an important tool for diagnosing and treating heart rhythm disorders such as atrial fibrillation (AF). One of these parameters is the fibre direction, often assumed to be known in conductivity estimation methods. In this paper, a novel method to estimate the fibre direction from EGMs is presented. This method is based on local conduction slowness vectors of a propagating activation wave. These conduction slowness vectors follow an elliptical pattern that depends on the underlying conductivity parameters. The fibre direction and conductivity anisotropy ratio can therefore be estimated by fitting an ellipse to the conduction slowness vectors. Applying the presented method on simulated data shows that it can estimate the fibre direction more accurately than existing methods, and that its performance depends mostly on the range of wavefront directions present in the measurement area. The main advantage of the presented method is that it still functions relatively well in the presence of conduction blocks, as long as the surrounding tissue is approximately homogeneous.","Anisotropy; atrial fibrillation; conduction velocity; fibre direction; local activation time","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-11-05","","","Signal Processing Systems","","",""
"uuid:958f91bc-f0cb-4697-9747-0af91d0936da","http://resolver.tudelft.nl/uuid:958f91bc-f0cb-4697-9747-0af91d0936da","Influence of solder condition on effective thermal conductivity of two-directional random fibres: Pore-scale simulation","Xiao, Tian (Xi’an Jiaotong University; Xi’an University of Technology); Zhang, Qiaoling (Xi’an University of Technology); Yang, Xiaohu (Xi’an Jiaotong University; Xi’an University of Technology); Hooman, K. (TU Delft Process and Energy); Li, Guodong (Xi’an University of Technology)","","2023","It is indicated that the solder joint of the metal fibrous materials is a critical factor impacting the heat conduction. To reveal the mechanism by which solder joint sizes, solder joint skips, solder flux materials, and filling media affect the thermal conductivity of fibres, pore-scale numerical simulation is employed to study the thermal transport in two-directional (2-D) random fibres. Satisfactory agreement with existing data validates the numerical model. The dimensionless effective thermal conductivity (ETC) of the porous fibres increases with the solder joint sizes. As the solder joint size (i.e., solder joint ratio) increases by 3.06%, the in-plane (ke-in) and out-of-plane (ke-out) dimensionless ETC increase by 9.0% and 437.2%, respectively. However, the solder joint skips will weaken the thermal conductivity of the fibres. For the same fibre, the ETC of the fibre increases as the thermal conductivity of solders increases. Further, when the dissimilarity in thermal conductivity between the filling medium and the fibre is reduced, the fibre is less affected by the solder joint skips. Finally, it should be supplemented that the in-plane and out-of-plane ETC (ke-in and ke-out) of the fibre without any solder joint are reduced by an average of 14.3% and 98.8%, respectively.","Effective thermal conductivity (ETC); Metal fibre materials; Numerical simulation; Solder joints","en","journal article","","","","","","","","","","Process and Energy","","","",""
"uuid:3b57daa2-0d4b-4bb2-b732-a1eda5a420c3","http://resolver.tudelft.nl/uuid:3b57daa2-0d4b-4bb2-b732-a1eda5a420c3","Effects of curing on the hydro-mechanical behaviour of cement-bentonite mixtures for cut-off walls","Flessati, L. (TU Delft Geo-engineering); Vecchia, Gabriele Della (Politecnico di Milano); Musso, Guido (Politecnico di Torino)","","2023","Cement-bentonite cut-off walls are commonly employed in geoenvironmental applications to limit ground water flow and pollutant transport. The wide diffusion of this artificial material in the current practice is not only due to its low permeability, but also to its simplicity of use. In this paper, experimental evidences about the role of curing on the hydro-mechanical behaviour of cement-bentonite mixtures are presented. Different curing times and curing conditions (representative for either water saturated or hydrocarbon polluted soils) have been considered, and their effects on both hydraulic conductivity and mechanical response in oedometer and triaxial conditions have been assessed. A unified hydro-mechanical framework, accounting for the changes of material fabric occurring with curing time and environment, is formulated. The hydraulic conductivity is very well predicted by a Kozeny-Carman like equation, whereas the mechanical behaviour is finely reproduced via an enhanced elastic–plastic constitutive model.","Cement-bentonite mixtures; Constitutive modelling; Curing; Hydraulic conductivity; Hydro-mechanical properties","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:c5adf03f-d502-4605-9905-b5958c91f017","http://resolver.tudelft.nl/uuid:c5adf03f-d502-4605-9905-b5958c91f017","Atrial extrasystoles enhance low-voltage fractionation electrograms in patients with atrial fibrillation","van Schie, M.S. (Erasmus MC); Liao, Rongheng (Erasmus MC); Ramdat Misier, Nawin L. (Erasmus MC); Knops, Paul (Erasmus MC); Heida, Annejet (Erasmus MC); Taverne, Yannick J.H.J. (Erasmus MC); de Groot, N.M.S. (TU Delft Signal Processing Systems; Erasmus MC)","","2023","BACKGROUND AND AIMS: Atrial extrasystoles (AES) provoke conduction disorders and may trigger episodes of atrial fibrillation (AF). However, the direction- and rate-dependency of electrophysiological tissue properties on epicardial unipolar electrogram (EGM) morphology is unknown. Therefore, this study examined the impact of spontaneous AES on potential amplitude, -fractionation, -duration, and low-voltage areas (LVAs), and correlated these differences with various degrees of prematurity and aberrancy. METHODS AND RESULTS: Intra-operative high-resolution epicardial mapping of the right and left atrium, Bachmann's Bundle, and pulmonary vein area was performed during sinus rhythm (SR) in 287 patients (60 with AF). AES were categorized according to their prematurity index (>25% shortening) and degree of aberrancy (none, mild/opposite, moderate and severe). In total, 837 unique AES (457 premature; 58 mild/opposite, 355 moderate, and 154 severe aberrant) were included. The average prematurity index was 28% [12-45]. Comparing SR and AES, average voltage decreased (-1.1 [-1.2, -0.9] mV, P < 0.001) at all atrial regions, whereas the amount of LVAs and fractionation increased (respectively, +3.4 [2.7, 4.1] % and +3.2 [2.6, 3.7] %, P < 0.001). Only weak or moderate correlations were found between EGM morphology parameters and prematurity indices (R2 < 0.299, P < 0.001). All parameters were, however, most severely affected by either mild/opposite or severely aberrant AES, in which the effect was more pronounced in AF patients. Also, there were considerable regional differences in effects provoked by AES. CONCLUSION: Unipolar EGM characteristics during spontaneous AES are mainly directional-dependent and not rate-dependent. AF patients have more direction-dependent conduction disorders, indicating enhanced non-uniform anisotropy that is uncovered by spontaneous AES.","Anisotropy; Atrial extrasystole; Atrial fibrillation; Conduction disorders; Fractionation; High-resolution epicardial mapping; Low-voltage areas; Potential morphology; Sinus rhythm; Unipolar voltage","en","journal article","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:ff2acc59-10f2-4a4f-8315-07061d3f4f21","http://resolver.tudelft.nl/uuid:ff2acc59-10f2-4a4f-8315-07061d3f4f21","A comparative study between low- and high-tech methods for the detection and mitigation of illicit connections in stormwater systems","Schilperoort, Remy (Partners4UrbanWater); Post, Johan (Partners4UrbanWater); Klootwijk, Martijn (Municipality of Breda); Hoefeijzers, Bas (Municipality of Breda); Hof, Arjo (Municipality of Almere); Palsma, Bert (STOWA); Leenen, Imke (H2Oké Water & Health Consultancy); Makris, Konstantinos F. (Partners4UrbanWater); Langeveld, J.G. (TU Delft Sanitary Engineering; Partners4UrbanWater)","","2023","Illicit connections of wastewater to stormwater systems are the main drawback of separate sewer systems, as they lead to a direct discharge of untreated wastewater to the aquatic environment. Consequently, several inspection methods have been developed for detecting illicit connections. This study simultaneously applied several low- and high-tech methods for the detection of illicit connections in the same catchment (De Heuvel, the Netherlands). The methods included mesh wire screens for capturing coarse contamination, measurements of electroconductivity and temperature, sampling and quantification of Escherichia coli and extended-spectrum ß-lactamase-producing E. coli (ESBL-EC), DNA analysis via quantitative polymerase chain reaction for human-, dog-, and bird-specific fecal indicators, and distributed temperature sensing. Significant illicit connections could be identified using all methods. Nonetheless, hydraulic conditions and, predominantly, the sewage volume determine whether a misconnection can be detected by especially the low-tech methods. Using these results, the identified misconnections were repaired and biological and DNA analyses were repeated. Our results demonstrate that there were no changes in E. coli or ESBL-EC before and after mitigation, suggesting that these common markers of fecal contamination are not specific enough to evaluate the performance of mitigation efforts. However, a marked decrease in human wastewater markers (HF183) was observed.","Bacteroides; conductivity; DTS; E. coli; ESBL-EC; illicit connections","en","journal article","","","","","","","","","","","Sanitary Engineering","","",""
"uuid:20a002fb-dc3c-4f76-b4bc-d5765bf6056a","http://resolver.tudelft.nl/uuid:20a002fb-dc3c-4f76-b4bc-d5765bf6056a","Effect of probe size on phase-detection probe measurements of air-water flow properties in hydraulic jumps","Shi, Rui (Rio Tinto Iron Ore; University of Queensland); Wüthrich, D. (TU Delft Hydraulic Structures and Flood Risk); Chanson, Hubert (University of Queensland)","","2023","This experimental study investigated the air-water flow properties and bubble characteristics in hydraulic jumps with Froude numbers Fr1 = 2.4 and 6.3, using four dual-tip phase detection probes with sensor sizes from 0.25 mm to 0.64 mm. The hydraulic jumps were characterized by a fully breaking roller with substantial air entrainment and turbulent two-phase flow patterns. The measurements encompassed distributions of void fraction, bubble count rate, interfacial velocity and bubble clustering properties and the data sets were consistent with previous studies. The comparison of the different probes showed a small impact of the tested sensor sizes on the air-water flow properties, in terms of the trends, magnitude and maximum values. Some differences were observed in terms of the bubble count rate, with the larger probes detecting a lesser number of bubbles. The trend was further confirmed through a comparison with the data set of Chanson and Brattberg (2000) [10] with a smaller probe sensor size (Ø1 = 0.025 mm), in which the maxima of bubble count rates were almost twice that of the present dataset for identical flow conditions. The present results confirm that the traditional signal processing techniques can be used for relatively small probe sizes, although different approaches might be needed for larger probes which cannot detect sub-millimetric bubbles. Overall, the findings should facilitate the development of sturdier phase-detection needle probes and help breaching the gap between laboratory and prototype.","Air–water flow properties; Hydraulic jump; Phase detection conductivity probes; Physical modelling","en","journal article","","","","","","","","","","","Hydraulic Structures and Flood Risk","","",""
"uuid:1a9044e9-9cf9-4afa-8c03-0dfd410c2866","http://resolver.tudelft.nl/uuid:1a9044e9-9cf9-4afa-8c03-0dfd410c2866","Characterization of unipolar electrogram morphology: A novel tool for quantifying conduction inhomogeneity","Ye, Ziliang (Erasmus MC); van Schie, M.S. (TU Delft Biomechanical Engineering; Erasmus MC); Pool, Lisa (Erasmus MC); Heida, Annejet (Erasmus MC); Knops, Paul (Erasmus MC); Taverne, Yannick J.H.J. (Erasmus MC); Brundel, Bianca J.J.M. (Amsterdam UMC); de Groot, N.M.S. (TU Delft Biomechanical Engineering; TU Delft Signal Processing Systems; Erasmus MC)","","2023","Aims: Areas of conduction inhomogeneity (CI) during sinus rhythm may facilitate the initiation and perpetuation of atrial fibrillation (AF). Currently, no tool is available to quantify the severity of CI. Our aim is to develop and validate a novel tool using unipolar electrograms (EGMs) only to quantify the severity of CI in the atria. Methods and results: Epicardial mapping of the right atrium (RA) and left atrium, including Bachmann's bundle, was performed in 235 patients undergoing coronary artery bypass grafting surgery. Conduction inhomogeneity was defined as the amount of conduction block. Electrograms were classified as single, short, long double (LDP), and fractionated potentials (FPs), and the fractionation duration of non-single potentials was measured. The proportion of low-voltage areas (LVAs, <1mV) was calculated. Increased CI was associated with decreased potential voltages and increased LVAs, LDPs, and FPs. The Electrical Fingerprint Score consisting of RA EGM features, including LVAs and LDPs, was most accurate in predicting CI severity. The RA Electrical Fingerprint Score demonstrated the highest correlation with the amount of CI in both atria (r = 0.70, P < 0.001). Conclusion: The Electrical Fingerprint Score is a novel tool to quantify the severity of CI using only unipolar EGM characteristics recorded. This tool can be used to stage the degree of conduction abnormalities without constructing spatial activation patterns, potentially enabling early identification of patients at high risk of post-operative AF or selection of the appropriate ablation approach in addition to pulmonary vein isolation at the electrophysiology laboratory.","Atrial fibrillation; Conduction inhomogeneity; Diagnostic tool; Epicardial mapping; Sinus rhythm","en","journal article","","","","","","","","","","Biomechanical Engineering","Signal Processing Systems","","",""
"uuid:8775cff7-5db3-43b4-ba04-f7b25e13bdd7","http://resolver.tudelft.nl/uuid:8775cff7-5db3-43b4-ba04-f7b25e13bdd7","Temperature-Dependent Interplay between Structural and Charge Carrier Dynamics in CsMAFA-Based Perovskites","Zhao, J. (TU Delft ChemE/Opto-electronic Materials); Liu, X. (TU Delft ChemE/O&O groep); Wu, Zijin (Eindhoven University of Technology); Ibrahim, B. (TU Delft ChemE/O&O groep); Thieme, J. (TU Delft ChemE/O&O groep); Brocks, Geert (Eindhoven University of Technology; University of Twente); Tao, Shuxia (Eindhoven University of Technology); Bannenberg, L.J. (TU Delft RID/TS/Instrumenten groep); Savenije, T.J. (TU Delft ChemE/Opto-electronic Materials)","","2023","State-of-the-art triple cation, mixed halide perovskites are extensively studied in perovskite solar cells, showing very promising performance and stability. However, an in-depth fundamental understanding of how the phase behavior in Cs0.05FA0.85MA0.10Pb(I0.97Br0.03)3 (CsMAFA) affects the optoelectronic properties is still lacking. The refined unit cell parameters a and c in combination with the thermal expansion coefficients derived from X-ray diffraction patterns reveal that CsMAFA undergoes an α–β phase transition at ≈280 K and another transition to the γ-phase at ≈180 K. From the analyses of the electrodeless microwave photoconductivity measurements it is shown that shallow traps only in the γ-phase negatively affect the charge carrier dynamics. Most importantly, CsMAFA exhibits the lowest amount of microstrain in the β-phase at around 240 K, corresponding to the lowest amount of trap density, which translates into the longest charge carrier diffusion length for electrons and holes. Below 200 K a considerable increase in deep trap states is found most likely related to the temperature-induced compressive microstrain leading to a huge imbalance in charge carrier diffusion lengths between electrons and holes. This work provides valuable insight into how temperature-dependent changes in structure affect the charge carrier dynamics in FA-rich perovskites.","charge carrier dynamics; metal halide perovskites; microstrain; phase structure; shallow trap states; time-resolved microwave conductivity","en","journal article","","","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:ab748942-3e9f-48fe-8eea-53d8e76dac77","http://resolver.tudelft.nl/uuid:ab748942-3e9f-48fe-8eea-53d8e76dac77","Modeling rock damage during the long-term production process for hot dry rocks: Effects of additional conductivity on the production performance and economic efficiency","Xu, Fuqiang (China University of Petroleum - Beijing); Shi, Yu (Southwest Jiaotong University); Song, Xianzhi (China University of Petroleum - Beijing); Song, G. (TU Delft Applied Geology); Li, Shuang (China University of Petroleum - Beijing)","","2023","Hot dry rocks (HDRs), as an essential renewable energy source, its development has received widespread attention, especially for heat extraction. The fracture is the main seepage and heat transfer channel of circulating fluid in dense HDR reservoirs, and its conductivity evolution significantly affects the production performance. Most existing studies have focused on the change of fracture conductivity under elastic deformation without considering the additional conductivity induced by rock damage. However, the additional conductivity may have significant implications for rational design and timely adjustment of the production scheme. Therefore, a three-dimensional model at the field-scale is established, and it is used to analyze the effect of additional conductivity on production performance and economic efficiency. To simplify the calculation, the actual forms of damage are equivalent to the macroscopic physical evolution of the matrix. Results show that the rock is mainly tensile failure affected by thermal stress during production. The occurrence of damage will increase the reservoir permeability and porosity, reduce Young's modulus, and then reduce the differential pressure and production temperature, with a maximum reduction of 2.21 MPa and 14.21 °C in the control case, respectively. The effects of injection temperature, Young's modulus, and injection mass flow on the production performance are significant, followed by Poisson's ratio. In contrast, production pressure and fracture initial permeability had less influence. The maximum differential economic benefit of the control case is up to 2.289 million RMB. This research proves the necessity of damage study during the long-term production of HDRs.","Additional conductivity; Economic efficiency; Hot dry rocks; Long-term production; Production performance; Rock damage","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-06-26","","","Applied Geology","","",""
"uuid:d760c0c6-6487-47e6-9dfa-72bb8f990bc2","http://resolver.tudelft.nl/uuid:d760c0c6-6487-47e6-9dfa-72bb8f990bc2","Time-varying characteristics of saturated hydraulic conductivity in grassed swales based on the ensemble Kalman filter algorithm: A case study of two long-running swales in Netherlands","Yang, F. (TU Delft Hydraulic Structures and Flood Risk; Southeast University; IHE Delft Institute for Water Education; Monash University); Fu, Dafang (Southeast University; Monash University); Zevenbergen, C. (TU Delft Urban Design; IHE Delft Institute for Water Education); Boogaard, Floris C. (Deltares; Hanze Hogeschool Groningen); Singh, Rajendra Prasad (Southeast University; Monash University)","","2023","Saturated hydraulic conductivity (Ks) of the filler layer in grassed swales are varying in the changing environment. In most of the hydrological models, Ks is assumed as constant or decrease with a clogging factor. However, the Ks measured on site cannot be the input of the hydrological model directly. Therefore, in this study, an Ensemble Kalman Filter (EnKF) based approach was carried out to estimate the Ks of the whole systems in two monitored grassed swales at Enschede and Utrecht, the Netherlands. The relationship between Ks and possible influencing factors (antecedent dry period, temperature, rainfall, rainfall duration, total rainfall and seasonal factors) were studied and a Multivariate nonlinear function was established to optimize the hydrological model. The results revealed that the EnKF method was satisfying in the Ks estimation, which showed a notable decrease after long-term operation, but revealed a recovery in summer and winter. After the addition of Multivariate nonlinear function of the Ks into hydrological model, 63.8% of the predicted results were optimized among the validation events, and compared with constant Ks. A sensitivity analysis revealed that the effect of each influencing factors on the Ks varies depending on the type of grassed swale. However, these findings require further investigation and data support.","Ensemble Kalman filter; Grassed swales; Multivariate nonlinear regression; Nature based solution; Saturated hydraulic conductivity","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-06-12","","","Hydraulic Structures and Flood Risk","","",""
"uuid:e125c7a6-c711-4038-8b76-da2c9fb6df8e","http://resolver.tudelft.nl/uuid:e125c7a6-c711-4038-8b76-da2c9fb6df8e","Double-sided numerical thermal modeling of fan-out panel-level MOSFET power modules","Li, Wenyu (Fudan University); Chen, Wei (Fudan University); Jiang, Jing (Fudan University); Tang, H. (TU Delft Electronic Components, Technology and Materials; Fudan University); Fan, J. (TU Delft Electronic Components, Technology and Materials; Fudan University)","","2023","Double-sided packages for heat dissipation are an efficient thermal management mechanism for power semiconductor devices. A fan-out panel-level packaging (FOPLP), as one of the double-sided forms, exhibits excellent electro–thermal characteristics and provides low stray inductance and thermal resistance. Besides, the temperature at each point within the structure is closely related to its thermo–mechanical properties and device reliability. However, thermal resistance is limited in describing the temperature distribution. Finite element analysis (FEA) requires time-consuming construction of 3D models. Therefore, to depict the temperature distribution of FOPLP rapidly and accurately, a numerical heat transfer model was proposed for the double-sided package structure. The solution was obtained from the steady-state thermal balance Laplace equation using the separation of variables method. Several boundaries were analyzed to determine the specific parameters in the model. Finally, the temperature field predicted by the derived numerical model was compared with finite element simulation results. The proposed model was consistent with both Silicon (Si) and Silicon Carbide (SiC) FOPLP structures within the error of 15 % at the center of the device, which verified the validity and accuracy of the numerical model for double-sided heat dissipation. The proposed models and results could contribute to the development of effective thermal design tools for double-sided thermal power modules.","Double-sided package; Fan-out panel-level packaging; MOSFET power module; Numerical thermal modeling; Thermal conduction","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:28dfab8f-40dd-4b41-9db8-3bc9427c12f8","http://resolver.tudelft.nl/uuid:28dfab8f-40dd-4b41-9db8-3bc9427c12f8","Effect of injection water ionic strength on estimating hydraulic parameters in a 3D sand tank using silica encapsulated magnetic DNA particles","Chakraborty, S. (Universiteit Utrecht); Elhaj, Rayan (IHE Delft Institute for Water Education); Foppen, J.W.A. (TU Delft Water Resources); Schijven, Jack (Universiteit Utrecht; Rijksinstituut voor Volksgezondheid en Milieu (RIVM))","","2023","We investigated the applicability of Silica encapsulated, superparamagnetic DNA particles (SiDNAmag) in determining aquifer hydraulic parameters at different ionic strengths (1 mM, 5 mM, and 20 mM phosphate buffer) of injection suspension. Thereto, in a homogeneous, unconsolidated sand tank we pulse - injected two uniquely sequenced SiDNAmag at two injection points. At 0.5 m and 0.8 m downstream from the injection points, we measured the concentration of SiDNAmags at three vertically distributed and two horizontally distributed sampling locations. We estimated the hydraulic parameter distributions from the SiDNAmag breakthrough curves through a Monte – Carlo approach and compared the parameter distributions with salt tracer breakthrough curves. Our results indicated that at all the ionic strengths, the times of peak concentrations, and the shapes of the breakthrough curves were similar to the salt tracer. As compared to the salt, a 1 – 3 log units reduction in the maximum effluent concentration of SiDNAmag was due to kinetic attachment. The attachment rate reduced from 1 mM to 5 mM phosphate buffer possibly due to competitive adsorption of phosphate onto the favourable attachment sites. SiDNAmag attachment rate further increased in 20 mM buffer suspension, possibly due to the compression of electric double layer and reduction in energy barrier for attachment. The parameter distributions of hydraulic conductivity (k), effective porosity (ne), longitudinal dispersivity (αL), vertical transverse dispersivity (αTV /αL) and horizontal transverse dispersivity (αTH /αL) estimated from the SiDNAmag and the salt tracer breakthrough curves were statistically similar. Our work contributes to the applicability of colloidal SiDNAmags for determining hydraulic parameters at different ionic strength conditions.","Colloids; Effective porosity; Hydraulic conductivity; Longitudinal dispersivity; Sand tank","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:a59fd24f-ee96-471c-ae96-060243577de3","http://resolver.tudelft.nl/uuid:a59fd24f-ee96-471c-ae96-060243577de3","Using continuous electrical conductivity measurements to derive major solute concentrations in karst systems","Richieri, Beatrice (Technische Universität München); Bittner, Daniel (Erftverband; Technische Universität Dresden); Hartmann, Andreas (Technische Universität Dresden); Benettin, Paolo (Swiss Federal Institute of Technology); van Breukelen, B.M. (TU Delft Sanitary Engineering); Labat, David (Géosciences Environnement Toulouse); Chiogna, Gabriele (Technische Universität München; University of Innsbruck)","","2023","Hydrochemical data of karst springs provide valuable insights into the internal hydrodynamical functioning of karst systems and support model structure identification. However, the collection of high-frequency time series of major solute species is limited by analysis costs. In this study, we develop a method to retrieve the individual solute concentration time series and their uncertainty at high temporal resolution for karst springs by using continuous observations of electrical conductivity ((Figure presented.)) and low-frequency ionic measurements. Due to the large ion content and non-negligible concentrations of aqueous complexes in karst systems, the concentration of each solute species occurring as free ion and as part of aqueous complexes are computed separately. The concentration of species occurring as free ions are computed considering their contributions to the total (Figure presented.), whereas the concentration of the species as part of complexes are obtained from speciation calculations. The pivotal role of the complexation processes for the reconstruction of solute concentration time series starting from the (Figure presented.) signal is investigated in two karstic catchments with different geologies and temporal resolution of the available hydrochemical datasets, that is the Kerschbaum dolostone system in Austria and the Baget limestone system in France. The results show that complexation processes are significant and should be considered for the estimation of the total solute concentration in case of SO4, Ca, Mg and HCO3. The (Figure presented.) signal of a karst spring can be used to interpolate and quantify the dynamics of those solutes characterized by large contribution (approximately >6%) to the total (Figure presented.) and low relative variability, that is HCO3, Ca and Mg. Moreover, the presented method can be used to estimate concentrations of solutes when applied to karst systems with stationary and hydrogeochemical homogeneous contributing area. On the contrary, the method is affected by large uncertainty in case of dynamic systems characterized by varying contributions of water from different geological areas. This study aims to contribute to the problem of hydrogeochemical data availability and to support future works on karst systems conceptualization.","electrical conductivity decomposition; high-resolution hydrochemical data; hydrochemical modelling; karst","en","journal article","","","","","","","","","","","Sanitary Engineering","","",""
"uuid:127508d1-5446-40da-acc1-b60be44f9dd1","http://resolver.tudelft.nl/uuid:127508d1-5446-40da-acc1-b60be44f9dd1","Thermal conductivity of binary ceramic composites made of insulating and conducting materials comprising full composition range – Applied to yttria partially stabilized zirconia and molybdenum disilicide","Cernuschi, Federico (RSE S.p.a.); Kulczyk-Malecka, Justyna (The University of Manchester; Manchester Metropolitan University); Zhang, Xun (The University of Manchester); Nozahic, Franck (Ecole Nationale Supérieure des Ingénieurs en Arts Chimiques et Technologiques); Estournès, Claude (Ecole Nationale Supérieure des Ingénieurs en Arts Chimiques et Technologiques); Sloof, W.G. (TU Delft Team Joris Dik)","","2023","The thermal diffusivity and conductivity of dense and porous binary composites having an insulating and conducting phase were studied across its entire composition range. Experimental evaluation has been performed with MoSi2 particles embedded into yttria partially stabilized zirconia (YPSZ) as prepared by spark plasma sintering (SPS). The thermal diffusivity of the composites was measured with Flash Thermography (FT) and Laser Flash Analysis (LFA) techniques. Subsequently, the thermal conductivity was determined with the measured heat capacity and density of the composites. The actual volume fraction of the conducting phase of the composites was determined with image analysis of X-ray maps recorded with scanning electron microscopy (SEM). The phases present and their density were determined with X-ray diffractometry (XRD) using Rietveld refinement. The thermal diffusivity increases with increasing volume fraction of MoSi2. Porosity reduces the thermal diffusivity, but the effect diminishes with high volume fractions MoSi2. The thermal diffusivity as a function of the MoSi2 volume fraction of the YPSZ composites is captured by modelling, which includes the porosity effect and the high conductivity paths due to the percolation of the conductive phase.","Composites; Percolation; Spark Plasma Sintering; Thermal Barrier; Thermal conductivity; Thermal diffusivity","en","journal article","","","","","","","","","","","Team Joris Dik","","",""
"uuid:be761a38-a87a-4e87-9343-7f838ccf6c89","http://resolver.tudelft.nl/uuid:be761a38-a87a-4e87-9343-7f838ccf6c89","Modelling and Analysis of Atrial Epicardial Electrograms: An approach based on graph signal processing and confirmatory factor analysis","Sun, M. (TU Delft Signal Processing Systems)","van der Veen, A.J. (promotor); Hendriks, R.C. (promotor); de Groot, N.M.S. (promotor); Delft University of Technology (degree granting institution)","2022","Atrial fibrillation (AF) is a frequently encountered cardiac arrhythmia characterized by rapid and irregular atrial activity, which increases the risk of strokes, heart failure and other heart-related complications. The mechanisms of AF are complicated. Although various mechanisms were proposed in previous research, the precise mechanisms of AF are not clear yet and the optimal therapy for AF patients are still under debated. A higher success rate of AF treatments requires a deeper understanding of the problem of AF and potentially a better screening of the patients.
In order to study AF, instead of using human body surface ECGs, we use the epicardial electrograms (EGMs) obtained directly from the epicardial sites of the human atria during open heart surgery. This data is measured using a high-resolution mapping array and exhibits irregular properties during AF. Although different studies have analyzed electrograms in time and frequency domain, there remain many open questions that require alternative and novel tools to investigate AF.
Experience in signal processing suggests that incorporating the spatial dimension into the time-frequency analysis on the multi-electrode electrograms may provide improved insights on the atrial activity. However, the electrophysiologcial models for describing spatial propagation are relatively complex and non-linear such that conventional signal processing methods are less suitable for a joint space, time, and frequency domain analysis. It is also difficult to use very detailed electrophysiologcial models to extract tissue parameters related to AF from the high-dimensional data.
In this dissertation, we wish to propose a radically different approach to study and analyze the EGMs from a higher abstraction level and from different perspectives to get more understanding of the characteristics of AF. We also aim to develop a simplified electrophysiological model that can capture the spatial structure of the data and propose an efficient method to estimate the tissue parameters, which are helpful to analyze the electropathology of the tissue, e.g., cell activation time or conductivity.
In the first part of this study, we put forward a graph-time spectral analysis framework to analyze EGMs during normal heart rhythm and AF with a higher-level model. To capture the frequency content along both time domain and graph domain, we propose the joint graph and short-time Fourier transform, which allows us to evaluate the temporal and spatial variation of EGMs and capture the interaction between space and time. The spectral analysis of the EGMs helps us to recognize atrial fibrillation impact on the atrial activity and identify the differences between the atrial activity and the ventricular activity. We find that the difference in graph smoothness between the atrial and ventricular activities enables us to better extract the atrial activity from the noisy measurements.
The second part of this study is to find a simplified but accurate enough electrophysiological model for the high dimensional EGMs and to make more efficient use of the data to detect the arrythmogenic substrate that causes abnormalities in atrial tissue. In this dissertation, we develop the cross power spectral density matrix (CPSDM) model of the multi-electrode EGMs and make use of an effective method called confirmatory factor analysis (CFA) to jointly estimate the model parameters. The conductivity, the activation time, and the anisotropy ratio are useful parameters to determine abnormalities in cardiac tissue and are therefore the target parameters to be estimated. With the reasonable assumptions that the conductivity parameters and the anisotropy parameters are constant across different frequencies and heart beats, and the activation time of cells are constant across different frequencies, we propose simultaneous CFA (SCFA) to jointly estimate these parameters using multiple frequencies and multiple heart beats. The identifiability conditions which need to be satisfied in the CFA problem are used to find the relationship between the desired resolution and the required amount of data. Evaluations on the simulated data and the clinical data demonstrate that the proposed method can localize the conduction blocks in the tissue and reconstruct the clinical EGMs well using the estimated parameters.","Atrial fibrillation; epicardial electrograms; spectral analysis; graphtime signal processing; electrophysiological model; cross-power spectral density matrix model; conductivity estimation; activation time estimation; anisotropy ratio estimation; confirmatory factor analysis","en","doctoral thesis","","978-94-6366-545-2","","","","","","","","","Signal Processing Systems","","",""
"uuid:d6f35adf-486e-453a-9ae9-679a81105bed","http://resolver.tudelft.nl/uuid:d6f35adf-486e-453a-9ae9-679a81105bed","High-Mobility TCO-Based Contacting Schemes for c-Si Solar Cells","Han, C. (TU Delft Photovoltaic Materials and Devices)","Zeman, M. (promotor); Zhang, Xiaodan (promotor); Isabella, O. (promotor); Delft University of Technology (degree granting institution)","2022","In the efficiency-driven photovoltaic (PV) industry, the market dominating crystalline silicon (c-Si) technology has been developing towards PV devices with carrier-selective passivating contacts (CSPCs). Especially, the silicon heterojunction (SHJ) solar cell, based on hydrogenated amorphous silicon (a-Si:H) contact stacks, and the poly-Si solar cell, based on ultrathin SiOx/poly-Si passivating contacts, pave the way for power conversion efficiencies above 26%, approaching the theoretical limit of the c-Si solar cell. In case of front/back-contacted (FBC) architectures, to minimize the optical parasitic absorption at the emitter and/or surface field side(s), thin doped silicon layers are normally applied, which exhibit high sheet resistance. Accordingly, transparent conductive oxide (TCO) layers are required to ensure sufficient lateral carrier transport towards the metal electrodes. However, problems still exist in contacting schemes for high-efficiency solar cell design towards future multi-terawatt production of PV modules, regarding the development of TCO layer with high carrier mobility (μ), its integration into specific device structures, and more importantly, the material availability. In this work, we present three types of TCO materials. They are tin-, fluorine- and tungsten-doped indium oxide layers, namely, ITO, IFO, and IWO. RF magnetron sputtering approach has been utilized to deposit the films. The TCOs are integrated into both low thermal-budget SHJ and high thermal-budget poly-Si solar cells. Further, to address the sustainability implication related to indiumconsumption, we propose a strategy of bifacial SHJ solar cell with reduced TCO use. Meanwhile, to reduce silver (Ag) consumption, as well as to reach good solar cell performance in our laboratory, we have developed a platformfor bifacial copper (Cu)-platingmetallization approach. Specific results are summarized as follows...","transparent conductive oxide (TCO); bifacial copper-plating; indium use reduction; c-Si solar cells","en","doctoral thesis","","978-94-6421-734-6","","","","","","","","","Photovoltaic Materials and Devices","","",""
"uuid:b4357fc6-7d06-4394-bf2f-796958d891d4","http://resolver.tudelft.nl/uuid:b4357fc6-7d06-4394-bf2f-796958d891d4","Joint cardiac tissue conductivity and activation time estimation using confirmatory factor analysis","Sun, M. (TU Delft Signal Processing Systems); de Groot, N.M.S. (Erasmus MC); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2022","Mathematical models of the electrophysiology of cardiac tissue play an important role when studying heart rhythm disorders like atrial fibrillation. Model parameters such as conductivity, activation time, and anisotropy ratio are useful parameters to determine the arrhythmogenic substrate that causes abnormalities in the atrial tissue. Existing methods often estimate the model parameters separately and assume some of the parameters to be known as a priori knowledge. In this work, we propose an efficient method to jointly estimate the parameters of interest from the cross power spectral density matrix (CPSDM) model of the electrograms. By applying confirmatory factor analysis (CFA) to the CPSDMs of multi-electrode electrograms, we can make use of the spatial information of the data and analyze the relationship between the desired resolution and the required amount of data. With the reasonable assumptions that the conductivity parameters and the anisotropy parameters are constant across different frequencies and heart beats, we estimate these parameters using multiple frequencies and multiple heart beats simultaneously to easier satisfy the identifiability conditions in the CFA problem. Results on the simulated data show that using multiple heart beats decreases the estimation errors of the conductivity and the estimated activation time parameters. The experimental results on clinical data show that using multiple heart beats for parameter estimation can reduce the reconstruction errors of the clinical electrograms, which further demonstrates the robustness of the proposed method.","Activation time estimation; Conductivity estimation; Confirmatory factor analysis; Cross power spectral density","en","journal article","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:7564223b-643f-44c5-b9d9-c8bffdbb933f","http://resolver.tudelft.nl/uuid:7564223b-643f-44c5-b9d9-c8bffdbb933f","Screen Printed Fire-Through Contact Formation for Polysilicon-Passivated Contacts and Phosphorus-Diffused Contacts","Chaudhary, A. (International Solar Energy Research Center (ISC)); Hos, Jan (International Solar Energy Research Center (ISC)); Lossen, Jan (International Solar Energy Research Center (ISC)); Huster, Frank (Universität Konstanz); Kopecek, Radovan (International Solar Energy Research Center (ISC)); van Swaaij, R.A.C.M.M. (TU Delft Photovoltaic Materials and Devices); Zeman, M. (TU Delft Electrical Sustainable Energy)","","2022","In this article, we investigate the passivation quality and electrical contact properties for samples with a 150 nm thick n+ polysilicon layer in comparison to samples with a phosphorus diffused layer. High level of passivation is achieved for the samples with n+ polysilicon layer and an interfacial oxide underneath it. The contact properties with screen-printed fire-through silver paste are excellent (no additional recombination from metallization and specific contact resistivity (ρc) ≤ 2 mΩ·cm2) for the samples with the polysilicon layers. Fast-firing peak temperature was varied during the contact formation process; this was done to see the trend in the contact properties with the change in the thermal budget. The differences in the J0met and ρc for the two different kinds of samples are explained with the help of high-resolution scanning electron microscope imaging. Finally, we prepare M2-sized n-passivated emitter rear totally (PERT) diffused solar cells with a 150 nm thick n+ polysilicon based passivated rear contact. The best cell achieved an efficiency of 21.64%, with a Voc of 686 mV and fill factor of 80.2%.","Conductivity; Cross-sectional scanning electron microscope (SEM); Metallization; metallization; passivated contacts; Passivation; Phosphorus; phosphorus-doped layer; Photovoltaic cells; polysilicon; screen printing; Silicon; Silver","en","journal article","","","","","","","","","","Electrical Sustainable Energy","Photovoltaic Materials and Devices","","",""
"uuid:3d8cd692-b9c6-4263-8984-3b0c781b2709","http://resolver.tudelft.nl/uuid:3d8cd692-b9c6-4263-8984-3b0c781b2709","Ionic strength of the liquid phase of different sludge streams in a wastewater treatment plant","Prot, T.J.F. (TU Delft BT/Environmental Biotechnology; Wetsus, Centre for Sustainable Water Technology); Korving, L. (Wetsus, Centre for Sustainable Water Technology); van Loosdrecht, Mark C.M. (TU Delft BT/Environmental Biotechnology)","","2022","In a wastewater treatment plant (WWTP), several sludge streams exist and the composition of their liquid phase varies with time and place. For evaluating the potential for formation of precipitates and equilibria for weak acids/bases, the ionic strength and chemical composition need to be known. This information is often not available in literature, and even neglected in chemical model-based research. Based on a literature review, we proposed three ranges of concentration (low, typical and high) for the major constituents of the liquid phase of the different streams in a WWTP. The study also discusses the reasons for the concentration evolution, and the exceptional cases, to allow readers to consider the right range depending on their situation. The ionic strength of the different streams and the contribution of its constituents were calculated based on the ionic composition. The major contributors to the ionic strength for the wastewater-based streams (influent, effluent and mixed sludge) were Na+, Cl-, Mg2+ and Ca2+, representing 50-70% of the ionic strength. For digestate, NH4+ and HCO3- accounted for 65-75% of the ionic strength. Even though the ionic strength is recognized to impact several important wastewater treatment processes, its utilization in literature is not always adequate, which is discussed in this study.","conductivity; CPR; digestion; EBPR; wastewater composition; WWTP","en","journal article","","","","","","","","","","","BT/Environmental Biotechnology","","",""
"uuid:058ef33f-e4ec-4714-b33d-96f8dd51954b","http://resolver.tudelft.nl/uuid:058ef33f-e4ec-4714-b33d-96f8dd51954b","Identifying sources of infiltration and inflow in sanitary sewers in a northern community: comparative assessment of selected methods","Panasiuk, Oleksandr (Luleå Univ. of Technology); Hedström, Annelie (Luleå Univ. of Technology); Langeveld, J.G. (TU Delft Sanitary Engineering; Partners4UrbanWater); Viklander, Maria (Luleå Univ. of Technology)","","2022","Infiltration and inflow (I/I) into sanitary sewers causes numerous negative effects on the whole wastewater management system and ultimately, on the receiving waters. Consequently, a number of methods have been developed to analyse the performance of sewer systems with respect to I/I, including: distributed temperature sensing (DTS), closed-circuit television (CCTV) inspections, flow and conductivity measurements, automatic or grab sampling of ammonium, smoke testing, and visual inspection of manholes. Such methods were compared in an application to sanitary sewers in a small community and assessed with respect to their accuracy and ability to identify locations of sources of I/I, as well as temporal and spatial resolutions of the obtained results. Furthermore, different approaches to ammonium sampling during I/I monitoring campaigns were discussed. It was concluded that among the methods tested in this study, DTS had the highest temporal and spatial resolution, while ammonium grab sampling showed promise for initial screening of large catchments.","ammonium; closed-circuit television inspection; conductivity; distributed temperature sensing; infiltration and inflow; wastewater","en","journal article","","","","","","","","","","","Sanitary Engineering","","",""
"uuid:f53ead41-a958-458f-8cbc-3e0097001d5b","http://resolver.tudelft.nl/uuid:f53ead41-a958-458f-8cbc-3e0097001d5b","Finite Element Modeling for Thermal Conductivity of Cement-based Encapsulation Materials","Gao, Hanyan (Fudan University); Zhang, Jing (Heraeus Materials Technology); Zhu, Yingcan (University of Southern Queensland); Guo, Ruiqian (Fudan University); Zhang, Wanlu (Fudan University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Liu, Pan (Fudan University; Research Institute of Fudan University, Ningbo; Yiwu Research Instiute of Fudan)","","2022","With the trend of miniaturization and the increasing power density, the operating temperature of electronic devices keeps climbing, especially for wide band-gap semiconductors such as silicon carbide and gallium nitride. The high operating temperature up to 250℃ brings challenges to encapsulation materials since traditional encapsulation materials such as epoxy resins and silicone gels hardly bear temperatures above 200℃. Calcium aluminate cement (CAC) was proved to be a promising encapsulation material, which owns high thermal stability with its operating temperature of up to 300℃. Based on its satisfied thermal stability and low cost, the thermal conductivity of CAC was researched in this work with different ratios of 10-μm-sphere-Alumina (Al 2 O 3 ) fillers at different temperatures, which formed μm-scale CAC-Al 2 O 3 composites. In this work, we focused on the thermal conductivity of CAC-Al 2 O 3 composites aiming for encapsulation applications in power electronics packaging. The thermal conductivities of μm-scale CAC-Al 2 O 3 composites by the laser-flash method from room temperature to 350℃ were firstly measured. Results showed with an increasing content of fillers, the TC of CACAl 2 O 3 will increase accordinglyIt also illustrated that calcium aluminate cement was a high thermal stable encapsulation material with thermal conductivity over epoxy resins. Then, the Finite Element Model (FEM) was established and calibrated by experimental data for thermal conductivity simulation. The FEM model accuracy reached 90%. Such models for new filler materials are effective to minimize material development by actual experiments and characterizations, for CAC composite with different fillers. It also provides an alternative method in predicting other physical properties of composites such as coefficient of thermal expansion, porosity, etc.","Encapsulation; Finite element modeling; Cement; Thermal conductivity; Electronic packaging","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Electronic Components, Technology and Materials","","",""
"uuid:11ea31ec-b716-402f-a225-9ecf6332dfcf","http://resolver.tudelft.nl/uuid:11ea31ec-b716-402f-a225-9ecf6332dfcf","Controlling the Oxygen Defects Concentration in a Pure BiFeO3 Bulk Ceramic","Tuluk, A. (TU Delft Novel Aerospace Materials); Brouwer, J.C. (TU Delft Team Marcel Hermans); van der Zwaag, S. (TU Delft Novel Aerospace Materials)","","2022","BiFeO 3 is a multiferroic material with a perovskite structure that has a lot of potential for use in sensors and transducers. However, obtaining pure single-phase BiFeO 3 ceramic with a low electrical conductivity via solid-state reactions remains a problem that limits its application. In this work, the suppression of secondary phases in BiFeO 3 was studied by varying the compositional parameters and the sintering temperature. The addition of 1% Bi 2O 3 to the stoichiometric precursor mixture prevented the formation of secondary phases observed when sintering stoichiometric precursors. The pure phase ceramic had a p-type conductivity and a three-decade lower electrical conductivity as measured by impedance spectroscopy. Annealing of optimally synthesized material at different partial pressures of oxygen in an oxygen–nitrogen gas atmosphere showed that the reason for this type of conductivity lies in the high concentration of defects associated with oxygen. By annealing in various mixtures of nitrogen and oxygen, it is possible to control the concentration of these defects and hence the conductivity, which can go down another two decades. At a pO 2 (Formula presented.) the conductivity is determined by intrinsic charge carriers in the material itself.","bismuth ferrite; electrical conductivity; impedance spectroscopy; oxygen defects; atmosphere","en","journal article","","","","","","","","","","","Novel Aerospace Materials","","",""
"uuid:2bd55523-2133-475c-9304-56ccabcace4d","http://resolver.tudelft.nl/uuid:2bd55523-2133-475c-9304-56ccabcace4d","Comparison of Two and Three-Level AC-DC Rectifier Semiconductor Losses with SiC MOSFETs Considering Reverse Conduction","Yu, G. (TU Delft DC systems, Energy conversion & Storage); Soeiro, Thiago B. (TU Delft DC systems, Energy conversion & Storage); Dong, J. (TU Delft DC systems, Energy conversion & Storage); Bauer, P. (TU Delft DC systems, Energy conversion & Storage)","","2022","This paper presents the semiconductor losses analytical equations in closed form for two-level voltage source converter, three-level neutral point clamped (NPC) and three-level T-Type PFC topologies in high power applications. The reverse parallel current conduction between the SiC MOSFETs channel and body diode is considered. A circuit simulation model is built in PLECS to estimate the semiconductor losses and to verify the accuracy of the developed analytical model. A calculation example of the semiconductor losses of a 200 kW three-phase rectifier is shown.","Silicon carbide; Computational modeling; «AC-DC converter»; «Analytical losses computation»; «Conduction losses»; «Silicon Carbide (SiC)>>; «Shunt current»","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-04-17","","","DC systems, Energy conversion & Storage","","",""
"uuid:f76d5cd9-482f-4e24-bff8-a0ec22e4da31","http://resolver.tudelft.nl/uuid:f76d5cd9-482f-4e24-bff8-a0ec22e4da31","A facile method to prepare oriented boron nitride-based polymer composite with enhanced thermal conductivity and mechanical properties","Chen, Jing (Fudan University; Chinese Academy of Sciences; Southern University of Science and Technology); Liu, X. (TU Delft Electronic Components, Technology and Materials); Zeng, Xiao Liang (Chinese Academy of Sciences); Ye, Huai Yu (Southern University of Science and Technology; Chongqing University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; Fudan University)","","2022","Hexagonal boron nitride (BN) is often used as filler to improve the thermal conductivity of polymer matrix due to its high thermal conductivity. However, previously reported BN-based composites always have a high in-plane thermal conductivity, which is not beneficial for vertical heat dissipation. In addition, high BN content results in the deterioration of the mechanical properties. Here, we report a feasible method to prepare a BN/silicone rubber (SiR) composite with oriented BN in organosilicon matrix via a vacuum-assisted self-assembly technique. The BN/SiR composite displays a 1270% higher (2.74 W/(m·K)) thermal conductivity than that of neat organosilicon matrix (0.20 W/(m·K)). The oriented BN nanosheets increase the polymer's adhesive force and exhibit excellent compression cycle performance. In turn, these features support its superiority as thermal interface material in the light-emitting diode chips heat dissipation application.","Boron nitride; Mechanical property; Polymer composites; Thermal conductivity; Vacuum-assisted self-assembly method","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Electronic Components, Technology and Materials","","",""
"uuid:30b9ad6b-6350-4d19-8a83-61f1d4643768","http://resolver.tudelft.nl/uuid:30b9ad6b-6350-4d19-8a83-61f1d4643768","Concentration and pressure measurements of dense sand and gravel multiphase flows under transient flow conditions in a vertically oriented closed conduit: Assessment of system and sensor performance","van Wijk, J. M. (Royal IHC); de Hoog, E. (Royal IHC); Talmon, A.M. (Deltares); van Rhee, C. (TU Delft Offshore and Dredging Engineering; TU Delft Rivers, Ports, Waterways and Dredging Engineering)","","2022","The hydraulic transport of sediments in sediment–water multiphase mixtures is an important process in nature and many industrial applications. The flows are characterized by complex transient phenomena, in which the overall system scale and the particle scale are equally important. Experimental research into dense mixture flows is focused on measurement of flowrates, differential pressures and concentrations of the suspended sediments. Concentration measurements are especially challenging in the case of coarse particles (beyond millimeter size scale) flowing in dense mixtures, limiting the range of available sensors for accurately measuring the in-situ solids concentrations. For the investigation of transient processes, a quick sensor response is required, which makes concentration measurement based on mixture conductivity an interesting option. This study is focused on combined concentration and pressure measurements in dense sediment–water mixtures with coarse particles in a vertically oriented closed conduit, using differential pressure sensors over the vertical segments and conductivity probes for measuring the mixture concentration. We experimentally investigated the dispersion process of an initially densely packed batch of sand and gravel by measuring the concentration on different segments of the conduit, resulting in data on mixture wall shear stresses for different sand and gravel mixtures and data of attenuation of concentration gradients in vertical upward and downward flow, in the conduit horizontal top section and in the centrifugal pump. We describe in the detail the sensor calibration and data processing method, giving a best practice for the use of conductivity concentration sensors in dense coarse particle mixtures, and we suggest a novel method for analysis of density wave amplification and attenuation based on concentration measurements in general, which allows for the detailed analysis of transient multiphase flow phenomena at pipe system component level.","Conductivity concentration measurement; Dense sediment multiphase flow; Density wave attenuation; Pressure measurement; Transient flow conditions","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Offshore and Dredging Engineering","","",""
"uuid:d37a273d-9966-4f19-871b-fae1c2166e7a","http://resolver.tudelft.nl/uuid:d37a273d-9966-4f19-871b-fae1c2166e7a","A comprehensive review on the long-term performance of stormwater biofiltration systems (SBS): Operational challenges and future directions","Yang, F. (TU Delft Hydraulic Structures and Flood Risk; Southeast University; Southeast University-Monash University Joint Research Centre for Future Cities; IHE Delft Institute for Water Education); Fu, Dafang (Southeast University; Southeast University-Monash University Joint Research Centre for Future Cities); Zevenbergen, C. (TU Delft Hydraulic Structures and Flood Risk; IHE Delft Institute for Water Education); Rene, Eldon R. (IHE Delft Institute for Water Education)","","2022","Stormwater biofiltration systems (SBS) are a popular technology for mitigating the negative effects of urbanization on the hydrological processes and water quality in urban areas. However, little is known about SBS's long-term performance in actual field conditions. The findings of a review of the scientific literature on the long-term performance of SBS are presented in this paper. The findings show that only a few studies have investigated the performance of SBS and its change over time, and that the results of laboratory and field experiments differed due to the presence of plants, regular maintenance, and some uncertain environmental factors. Based on the existing knowledge gaps in this field, the main challenges observed was the lack of long-term field data series, and the existing mathematical models are not able to accurately forecast the long-term performance of SBS. This could be owing to the difficulties in monitoring activities, the high costs involved and the unpredictability around the operational timeframe. Future study should concentrate on the implementation of simulation and modeling-based research in pilot and full-scale SBS, and the inclusion of new performance indicators should be considered as a priority.","Hydraulic conductivity; Long-term performance; Model simulation; Pollutant removal; Stormwater biofiltration system (SBS)","en","review","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Hydraulic Structures and Flood Risk","","",""
"uuid:dad02812-79f6-468e-9c99-433274e53b78","http://resolver.tudelft.nl/uuid:dad02812-79f6-468e-9c99-433274e53b78","Numerical analysis of effects of fins and conductive walls on heat transfer in side heated cavities — Onset of three-Dimensional phenomena in natural convection","Vesper, J.E. (TU Delft ChemE/Transport Phenomena; TU Delft J.M. Burgers Center for Fluid Mechanics); Tietjen, Sebastian C. (Student TU Delft); Chakkingal, M. (TU Delft ChemE/Transport Phenomena; TU Delft J.M. Burgers Center for Fluid Mechanics); Kenjeres, S. (TU Delft ChemE/Transport Phenomena; TU Delft J.M. Burgers Center for Fluid Mechanics)","","2022","In the present study, we analyse individual and combined effects of conductive horizontal walls and conductive fins on the natural convection of air in side heated cavities (SHC). The flow and heat transfer are studied for Rayleigh numbers in the range of 104−−109: Direct Numerical Simulation (DNS) is conducted for the lower and Large Eddy Simulation (LES) for the higher Rayleigh numbers (>108). Thermally conductive walls destabilize the flow yielding an earlier transition to turbulence and expedite the decay in boundary layer thickness with increase in Rayleigh number. The preheating/precooling along the conductive walls reduces the actual heat transfer at the vertical walls. Above the fin, instabilities are only marginally enhanced for adiabatic horizontal walls, whereas for conductive horizontal walls, plumes erupt from the fin. This localized Rayleigh-Bénard-like effect triggers 3D instabilities in the entire flow field and yields a steeper slope in Nusselt-Rayleigh diagram. The presence of a fin increases the integral heat transfer by 18% for adiabatic and 21% for conductive horizontal walls. We show that 2D and 3D simulations are similar for the smooth cases (i.e., without fin), but differ by 4% and 13% for the adiabatic and conductive fin cases respectively. The local heat transfer characteristics even deviates up to 50%, therefore a 2D simplification should be avoided.","Conductive walls; Differentially heated cavity; Finned cavity; Heat transfer; Instabilities; Natural convection; Side heated cavity; Stratification","en","journal article","","","","","","","","","","","ChemE/Transport Phenomena","","",""
"uuid:7f6a4faa-1fb0-41f7-8ac8-801e9f7a1250","http://resolver.tudelft.nl/uuid:7f6a4faa-1fb0-41f7-8ac8-801e9f7a1250","Towards bifacial silicon heterojunction solar cells with reduced TCO use","Han, C. (TU Delft Photovoltaic Materials and Devices; Shenzhen Institute of Wide-bandgap Semiconductors); Santbergen, R. (TU Delft Photovoltaic Materials and Devices); van Duffelen, Max (Student TU Delft); Procel Moya, P.A. (TU Delft Photovoltaic Materials and Devices; Universidad San Francisco de Quito); Zhao, Y. (TU Delft Photovoltaic Materials and Devices); Yang, G. (TU Delft Photovoltaic Materials and Devices); Zhang, Xiaodan (Nankai University); Zeman, M. (TU Delft Electrical Sustainable Energy); Mazzarella, L. (TU Delft Photovoltaic Materials and Devices); Isabella, O. (TU Delft Photovoltaic Materials and Devices)","","2022","Reducing indium consumption, which is related to the transparent conductive oxide (TCO) use, is a key challenge for scaling up silicon heterojunction (SHJ) solar cell technology to terawatt level. In this work, we developed bifacial SHJ solar cells with reduced TCO thickness. We present three types of In2O3-based TCOs, tin-, fluorine-, and tungsten-doped In2O3 (ITO, IFO, and IWO), whose thickness has been optimally minimized. These are promising TCOs, respectively, from post-transition metal doping, anionic doping, and transition metal doping and exhibit different opto-electrical properties. We performed optical simulations and electrical investigations with varied TCO thicknesses. The results indicate that (i) reducing TCO thickness could yield larger current in both monofacial and bifacial SHJ devices; (ii) our IWO and IFO are favorable for n-contact and p-contact, respectively; and (iii) our ITO could serve well for both n-contact and p-contact. Interestingly, for the p-contact, with the ITO thickness reducing from 75 nm to 25 nm, the average contact resistivity values show a decreasing trend from 390 mΩ cm2 to 114 mΩ cm2. With applying 25-nm-thick front IWO in n-contact, and 25-nm-thick rear ITO use in p-contact, we obtained front side efficiencies above 22% in bifacial SHJ solar cells. This represents a 67% TCO reduction with respect to a reference bifacial solar cell with 75-nm-thick TCO on both sides.","bifacial solar cell; silicon heterojunction solar cell; TCO reduction; transparent conductive oxide (TCO)","en","journal article","","","","","","","","","","Electrical Sustainable Energy","Photovoltaic Materials and Devices","","",""
"uuid:8f9c8fc1-b26b-48c5-b28e-4461421b7174","http://resolver.tudelft.nl/uuid:8f9c8fc1-b26b-48c5-b28e-4461421b7174","Effects of electrically conductive walls on turbulent magnetohydrodynamic flow in a continuous casting mold","Blishchik, A. (TU Delft ChemE/Transport Phenomena); Glavinić, Ivan (Helmholtz Zentrum Dresden Rossendorf); Wondrak, Thomas (Helmholtz Zentrum Dresden Rossendorf); van Odyck, Daniel (Tata Steel Europe Limited); Kenjeres, S. (TU Delft ChemE/Transport Phenomena)","","2022","In the present study, we have performed a series of numerical simulations of the turbulent liquid metal flow in a laboratory-scale setup of the continuous casting. The liquid metal flow was subjected to an external non-uniform magnetic field reproducing a realistic electromagnetic brake (EMBr) effect. The focus of this research was on the effects of the finite electrical conductivity of Hartmann walls on the flow and turbulence in the mold. To be able to simulate distributions of the electric potential and current in both the fluid and solid wall domains, we applied our recently developed and validated in-house conjugate MHD solver based on the open-source code OpenFOAM. The dynamic Large Eddy Simulation (LES) method was used to simulate the turbulent flow. The results obtained for the neutral (non-MHD) and MHD cases over a range of the imposed EMBr strengths – all for the perfectly electrically insulated walls – were compared with the available Ultrasound Doppler Velocimetry (UDV) measurements. A good agreement between simulations and experiments was obtained for all simulated cases. Next, we completed a series of simulations including a wide range of the finite electric conductivities (ranging from a weakly to perfectly conducting wall conditions) of the Hartmann walls for a fixed value of the imposed EMBr. The obtained results demonstrated a significant influence of the electric wall conductivities on the flow and turbulence reorganization. It is expected that here provided insights can be applicable for the new generation of the laboratory- and real-scale continuous casting setups.","Continuous casting; Dynamic LES; Electrically conducting walls; Lorentz force; Magnetic field; MHD; OpenFOAM","en","journal article","","","","","","","","","","","ChemE/Transport Phenomena","","",""
"uuid:77993e01-8754-48f2-a0e1-652d76136cc4","http://resolver.tudelft.nl/uuid:77993e01-8754-48f2-a0e1-652d76136cc4","Addressing the inconsistent electric fields of tDCS by using patient-tailored configurations in chronic stroke: Implications for treatment","van der Cruijsen, J. (TU Delft Biomechatronics & Human-Machine Control; Erasmus MC; Radboud University Medical Center); Dooren, R.F. (TU Delft Precision and Microsystems Engineering; Erasmus MC); Schouten, A.C. (TU Delft Biomechatronics & Human-Machine Control; University of Twente); Oostendorp, Thom F. (Radboud University Medical Center); Frens, Maarten A. (Erasmus MC); Ribbers, G.M. (TU Delft Biomechanical Engineering; Erasmus MC); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control; Northwestern University); Kwakkel, Gert (Northwestern University; Amsterdam UMC); Selles, R.W. (Erasmus MC)","","2022","Transcranial direct current stimulation (tDCS) is a promising tool to improve and speed up motor rehabilitation after stroke, but inconsistent clinical effects refrain tDCS from clinical implementation. Therefore, this study aimed to assess the need for individualized tDCS configurations in stroke, considering interindividual variability in brain anatomy and motor function representation. We simulated tDCS in individualized MRI-based finite element head models of 21 chronic stroke subjects and 10 healthy age-matched controls. An anatomy-based stimulation target, i.e. the motor hand knob, was identified with MRI, whereas a motor function-based stimulation target was identified with EEG. For each subject, we simulated conventional anodal tDCS electrode configurations and optimized electrode configurations to maximize stimulation strength within the anatomical and functional target. The normal component of the electric field was extracted and compared between subjects with stroke and healthy, age-matched controls, for both targets, during conventional and optimized tDCS. Electrical field strength was significantly lower, more variable and more frequently in opposite polarity for subjects with stroke compared to healthy age-matched subjects, both for the anatomical and functional target with conventional, i.e. non-individualized, electrode configurations. Optimized, i.e. individualized, electrode configurations increased the electrical field strength in the anatomical and functional target for subjects with stroke but did not reach the same levels as in healthy subjects. Considering individual brain structure and motor function is crucial for applying tDCS in subjects with stroke. Lack of individualized tDCS configurations in subjects with stroke results in lower electric fields in stimulation targets, which may partially explain the inconsistent clinical effects of tDCS in stroke trials.","EEG; Source localization; Stroke; tDCS; Volume conduction models","en","journal article","","","","","","","","","","Precision and Microsystems Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:34a9663f-1cf3-4d87-8cfb-b585f2fd4fa7","http://resolver.tudelft.nl/uuid:34a9663f-1cf3-4d87-8cfb-b585f2fd4fa7","A facile, green fabrication of aqueous nanofluids containing hydrophilic functionalized carbon nanotubes toward improving heat transfer in a closed horizontal flow passage","Akram, Naveed (University of Malaya; Mirpur University of Science and Technology, Mirpur); Hosseini, M. (University of New South Wales); Sadri, Rad (University of Tehran); Kazi, S.N. (University of Malaya); Kasaeian, Alibakhsh (University of Tehran); Yarmand, H. (TU Delft Human-Robot Interaction; TU Delft Emerging Materials); Hooman, K. (University of Queensland); Ahmad, Roslina (University of Malaya)","","2022","In the present research, the synthesis of highly stable multiwalled carbon nanotubes in aqueous media is developed using a one-pot, covalent and green functionalization technique to improve the heat transfer and hydrodynamic behavior of a horizontal stainless-steel tube subjected to a uniform heat flow at its outer surface. Instead of using corrosive inorganic acids, the free radical grafting of gallic acids is used in this procedure. In this work, GA-functionalized multiwalled carbon nanotubes water-based colloidal suspensions (nanofluids) were prepared at three different weight concentrations. Various characterization techniques comprising Fourier transform infrared spectroscopy, Raman spectroscopy, High resolution transmission Electron Microscopy, and zeta-potential measurements were performed and confirmed the success of MWCNT functionalization. The thermophysical properties were evaluated experimentally and validated using empirical correlations available in the literature. To prove the colloidal suspension stability, ultraviolet-visible spectroscopy was used, and the results showed that nanofluid was stable for almost 60 days. When the GAMWCNT concentration was increased, there was a significant improvement in the thermal conductivity. Moreover, the nanofluids' dynamic viscosity experienced a slight increment up to 7.30% when the GAMWCNTs were loaded relative to distilled water. Following the confirmation of the experimental setup's analytical correlations, tests for the colloidal GAMWCNT suspension flowing through a heated horizontal tube were carried out in a fully developed turbulent state. A significant enhancement in the convective heat transfer coefficient was obtained, with only minor growth in the relative pumping power by 33.05 and 1.19%, respectively. More importantly, the reported positive performance index indicator for all the Reynolds numbers of ranges shows the possibility of using the synthesized GAMWCNT aqueous suspensions as an alternative working fluid in heat transfer systems.","Convective heat transfer; Environmentally friendly; Multiwalled carbon nanotubes; Nanofluid; Thermal conductivity; Thermo-physical properties","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Human-Robot Interaction","","",""
"uuid:8e8320a4-495c-474a-9282-71e524ee28da","http://resolver.tudelft.nl/uuid:8e8320a4-495c-474a-9282-71e524ee28da","Charge Carrier Dynamics in Co-evaporated MAPbI3with a Gradient in Composition","Zhao, J. (TU Delft ChemE/Opto-electronic Materials); Li, Jia (Nanyang Technological University); Liu, X. (TU Delft ChemE/O&O groep); Bannenberg, L.J. (TU Delft RID/TS/Instrumenten groep); Bruno, Annalisa (Nanyang Technological University); Savenije, T.J. (TU Delft ChemE/Opto-electronic Materials)","","2022","Co-evaporation of metal halide perovskites by thermal evaporation is an attractive method since it does not require harmful solvents and enables precise control of the film thickness. Furthermore, the ability to manipulate the Fermi level allows the formation of a graded homojunction, providing interesting opportunities to improve the charge carrier collection efficiency. However, little is known about how these properties affect the charge carrier dynamics. In this work, the structural and optoelectronic properties of co-evaporated MAPbI3 films varying in thickness (100, 400, and 750 nm) with a gradient in composition are analyzed. The X-ray diffraction patterns show that excess PbI2 is only present in the thick layers. From X-ray photoelectron spectroscopy depth analysis, the I/Pb atomic ratio indicates methylammonium iodide deficiencies that become more prominent with thicker films, resulting in differently n-doped regions across the thick MAPbI3 films. We suggest that due to these differently n-doped regimes, an internal electric field is formed. Side-selective time-resolved microwave photo conductivity measurements show an elongation of the charge carrier lifetimes on increasing thickness. These observations can be explained by the fact that excess carriers separate under the influence of the electric field, preventing rapid decay in the thick films.","charge carrier dynamics; co-evaporation; metal halide perovskites; physical vapor deposition; time-resolved microwave conductivity","en","journal article","","","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:1e638e4c-ce53-42bb-95bb-fe5367838358","http://resolver.tudelft.nl/uuid:1e638e4c-ce53-42bb-95bb-fe5367838358","Spatial variability of leachate tables, leachate composition and hydraulic conductivity in a landfill stabilized by in-situ aeration","Gebert, J. (TU Delft Geo-engineering); de Jong, T. (TU Delft Geo-engineering); Meza Ramos, P.N. (TU Delft Geo-engineering); Rees-White, T. (TU Delft Geo-engineering; University of Southampton); Beaven, R.P. (University of Southampton); Lammen, J.K. (Afvalzorg - Sustainable Development, Assendelft)","","2022","Within the framework of the Dutch sustainable landfill project iDS, four compartments of the Dutch landfill Braambergen have been treated by in-situ aeration since 2017. The aeration infrastructure comprises 230 wells with a spacing of 15 to 20 m, distrib-uted over an area of around 10 ha, intercepting a waste body of 1.2 × 106 t of contam-inated soils, soil treatment residues, bottom ashes and construction and demolition waste. The wells, used in an alternating fashion for air injection and gas extraction, can also be used to monitor water tables within the waste body. In order to describe the spatial variability of waste hydraulics, design a larger scale leachate pumping test and, eventually, support model predictions of the site’s water balance and emission potential, analyses of leachate composition and pumping tests on individual wells have been conducted. The spatial variability of leachate quality and water tables is very high with no geospatial relationship between the sampling points. Each sampling point is representative of itself only. Large differences prevail not only between and across the compartments, but also between directly neighbouring wells. Both the small scale differences in leachate tables as well as in leachate quality indicate a spatial pattern of zones with low horizontal connectivity within the waste body. Recovery rates of drawdown in the wells yielded preliminary estimates of horizontal waste hydraulic conductivity in the order of 1×10-7 to 6×10-4 m/s.","Emission potential; Hydraulic conductivity; Leachate composition; Leachate tables; Waste hydrology","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:f912aeef-af94-4c32-890b-6917bb48f6a9","http://resolver.tudelft.nl/uuid:f912aeef-af94-4c32-890b-6917bb48f6a9","The effect of boron concentration on the electrical, morphological and optical properties of boron-doped nanocrystalline diamond sheets: Tuning the diamond-on-graphene vertical junction","Rycewicz, M.K. (TU Delft Micro and Nano Engineering; Gdansk University of Technology); Nosek, Adrian (University of California); Shin, D. (TU Delft QN/Steeneken Lab; Kavli institute of nanoscience Delft); Ficek, Mateusz (Gdansk University of Technology); Buijnsters, J.G. (TU Delft Micro and Nano Engineering); Bogdanowicz, Robert (Politechnika Gdanska)","","2022","In this paper, the effect of boron doping on the electrical, morphological and structural properties of free-standing nanocrystalline diamond sheets (thickness ~ 1 μm) was investigated. For this purpose, we used diamond films delaminated from a mirror-polished tantalum substrate following a microwave plasma-assisted chemical vapor deposition process, each grown with a different [B]/[C] ratio (up to 20,000 ppm) in the gas phase. The developed boron-doped diamond (BDD) films are a promising semiconducting material for sensing and high-power electronic devices due to band gap engineering and thermal management feasibility. The increased boron concentration in the gas phase induces a decrease in the average grain size, consequently resulting in lower surface roughness. The BDD sheets grown with [B]/[C] of 20,000 ppm reveal the metallic conductivity while the lower doped samples show p-type semiconductor character. The charge transport at room temperature is dominated by the thermally activated nearest-neighbor hopping between boron acceptors through impurity band conduction. At low temperatures (<300 K), the Arrhenius plot shows a non-linear temperature dependence of the logarithmic conductance pointing towards a crossover towards variable range hopping. The activation energy at high temperatures obtained for lowly-doped sheets is smaller than for nanocrystalline diamond bonded to silicon, while for highly-doped material it is similar. Developed sheets were utilized to fabricate two types of diamond-on-graphene heterojunctions, where boron doping is the key factor for tuning the shape of the current-voltage characteristics. The graphene heterojunction with the low boron concentration diamond sheet resembles a Schottky junction behavior, while an almost Ohmic contact response is recorded with the highly doped BDD sheet of metallic conductivity. The free-standing diamond sheets allow for integration with temperature-sensitive interfaces (i.e. 2D materials or polymers) and pave the way towards flexible electronics devices.","Boron-doped diamond (BDD); Electrical conductivity; Graphene; Heterojunction; Nanocrystalline sheets","en","journal article","","","","","","","","","","","Micro and Nano Engineering","","",""
"uuid:65656223-2574-4f19-b67d-717aac8fa6d9","http://resolver.tudelft.nl/uuid:65656223-2574-4f19-b67d-717aac8fa6d9","Application of metal, metal-oxide, and silicon-oxide based intermediate reflective layers for current matching in autonomous high-voltage multijunction photovoltaic devices","de Vrijer, T. (TU Delft Photovoltaic Materials and Devices); Miedema, Sander (Student TU Delft); Blackstone, Thijs (Student TU Delft); van Nijen, D.A. (TU Delft Photovoltaic Materials and Devices); Han, C. (TU Delft Photovoltaic Materials and Devices); Smets, A.H.M. (TU Delft Photovoltaic Materials and Devices)","","2022","A logical next step for achieving a cost price reduction per Watt peak of photovoltaics (PV) is multijunction PV devices. In two-terminal multijunction PV devices, the photo-current generated in each subcell should be matched. Intermediate reflective layers (IRLs) are widely employed in multijunction devices to increase reflection at the interface between subcells to enhance current generation in the subcell(s) positioned before the IRL, in reference to the incident light. In this work, the results of over 65 multijunction devices are presented, in order to explore the effect of different current matching approaches. The influence of variations in absorber thickness as well as thickness variations of different IRLs based on silicon-oxide, various transparent conductive oxides (TCO), and metallic layers on all-silicon multijunction PV devices is studied. Specifically, hybrid, 2-terminal, monolithically integrated silicon heterojunction (SHJ) and thin film nanocrystalline silicon (nc-Si:H) and amorphous silicon (a-Si:H) tandem and triple junction devices are processed. Based on these experiments, certain design rules for optimal current matching operation in multijunction devices are formulated. Finally, taking these design rules into account, record all-silicon multijunction devices are processed. Conversion efficiencies close 15% and (Formula presented.) V are demonstrated for triple junction SHJ/nc-Si:H/a-Si:H devices. Such conversion efficiencies for a wireless, high-voltage wafer-based all-silicon 2-terminal multijunction PV device opens the way for efficient autonomous solar-to-fuel synthesis systems as well as other wireless innovative approaches in which the multijunction solar cell is used not only as a photovoltaic current-voltage generator, but also as an ion-exchange membrane, electrochemical catalysts, and/or optical transmittance filter.","amorphous silicon; intermediate reflective layer; multijunction PV; nanocrystalline silicon; silicon oxide; solar to fuel; thin film silicon; transparent conductive oxide; tunnel recombination junction","en","journal article","","","","","","","","","","","Photovoltaic Materials and Devices","","",""
"uuid:75ae0077-3490-44cb-9978-8dac39f41840","http://resolver.tudelft.nl/uuid:75ae0077-3490-44cb-9978-8dac39f41840","Light-Enabled Access to Oxidative Polymerization: A Short Perspective on Bioinspired Oxidative Photopolymerization","Kumru, B. (TU Delft Aerospace Manufacturing Technologies)","","2022","Solar irradiation provides critical energy to conduct chemical reactions. Many light-sensitive materials, such as semiconductors, guide photoredox-induced chemical pathways to tailor favored chemical conversions. Polymer synthesis by light is popular, however mainly addressed by conducting radical-based polymerization strategies. Oxidative photopolymerization is an advanced method to form functional polymers that are otherwise formed through complicated reactions. Herein, infant-stage oxidative photopolymerization will be introduced with examples in the field.","conducting polymers; conjugated polymers; lignin; photooxidations; photopolymerizations; photoredox reactions","en","journal article","","","","","","","","","","","Aerospace Manufacturing Technologies","","",""
"uuid:8aa4a167-f047-4bd1-a7b5-3293c1ec24c4","http://resolver.tudelft.nl/uuid:8aa4a167-f047-4bd1-a7b5-3293c1ec24c4","Traps in the spotlight: How traps affect the charge carrier dynamics in Cs2AgBiBr6 perovskite","Caselli, V.M. (TU Delft ChemE/Opto-electronic Materials); Thieme, J. (TU Delft ChemE/O&O groep); Jöbsis, Huygen J. (Universiteit Utrecht); Phadke, S.A. (TU Delft Large Scale Energy Storage); Zhao, J. (TU Delft ChemE/Opto-electronic Materials); Hutter, Eline M. (Universiteit Utrecht); Savenije, T.J. (TU Delft ChemE/Opto-electronic Materials)","","2022","Suitable optoelectronic properties of lead halide perovskites make these materials interesting semiconductors for many applications. Toxic lead can be substituted by combining monovalent and trivalent cations, such as in Cs2AgBiBr6. However, efficiencies of Cs2AgBiBr6-based photovoltaics are still modest. To elucidate the loss mechanisms, in this report, we investigate charge dynamics in Cs2AgBiBr6 films by double-pulse excitation time-resolved microwave conductivity (DPE-TRMC). By exciting the sample with two laser pulses with identical wavelengths, we found a clear photoconductance enhancement induced by the second pulse even 30 μs after the first laser pulse. Modeling the DPE-TRMC results, complemented by photoluminescence and transient absorption, we reveal the presence of deep emissive electron traps, while shallow hole trapping is responsible for the long-lived transient absorption signals. These long-lived carriers offer interesting possibilities for X-ray detectors or photocatalysis. The DPE-TRMC methodology offers unique insight into the times involved in charge trapping and depopulation in Cs2AgBiBr6.","charge carrier dynamics; double-pulse excitation; excitons; lead-free perovskites; photoluminescence; thin film; time-resolved microwave conductance; transient absorption; trap states","en","journal article","","","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:42e121d6-43f8-4a65-8f42-d63430acbc61","http://resolver.tudelft.nl/uuid:42e121d6-43f8-4a65-8f42-d63430acbc61","Development of Low Hysteresis, Linear Weft-Knitted Strain Sensors for Smart Textile Applications","Bozali, B. (TU Delft Emerging Materials); Ghodrat, S. (TU Delft Emerging Materials); Plaude, L. (TU Delft Technical Support); van Dam, J.J.F. (TU Delft Technical Support); Jansen, K.M.B. (TU Delft Emerging Materials)","","2022","In recent years, knitted strain sensors have been developed that aim to achieve reliable sensing and high wearability, but they are associated with difficulties due to high hysteresis and low gauge factor (GF) values. This study investigated the electromechanical performance of the weft-knitted strain sensors with a systematic approach to achieve reliable knitted sensors. For two elastic yarn types, six conductive yarns with different resistivities, the knitting density as well as the number of conductive courses were considered as variables in the study. We focused on the 1 × 1 rib structure and in the sensing areas co-knit the conductive and elastic yarns and observed that positioning the conductive yarns at the inside was crucial for obtaining sensors with low hysteresis values. We show that using this technique and varying the knitting density, linear sensors with a working range up to 40% with low hysteresis can be obtained. In addition, using this technique and varying the knitting density, linear sensors with a working range up to 40% strain, hysteresis values as low as 0.03, and GFs varying between 0 and 1.19 can be achieved.","conductive yarns; hysteresis-free sensors; knitted strain sensors; smart textiles","en","journal article","","","","","","","","","","","Emerging Materials","","",""
"uuid:2e24a763-1885-46c9-a96e-0faf9a4867a9","http://resolver.tudelft.nl/uuid:2e24a763-1885-46c9-a96e-0faf9a4867a9","Elucidation of Enhanced Lithium Conductivity in Nanoporous Ionogel Using Solid State NMR","Weijers, M.J. (TU Delft ChemE/Materials for Energy Conversion and Storage); Karanth, P. (TU Delft ChemE/Materials for Energy Conversion and Storage); Ganapathy, S. (TU Delft RID/TS/Instrumenten groep); Mulder, F.M. (TU Delft ChemE/Materials for Energy Conversion and Storage)","","2022","Nanostructured solid composite electrolyte or nano-SCE, which is composed of an ionic liquid, nanoporous silica, and residuals of immobilized precursor components, shows promising synergistic properties. The ionic conductivity of nano-SCE is in the range of 2–5 mS cm−1, which exceeds the bulk ionic liquid conductivity at ambient temperature, while maintaining characteristics of a solid electrolyte such as having no leakage issues as the ionic liquid is confined, and lower flammability compared to conventional liquid electrolytes. In this study, the underlying mechanism of enhanced conductivity is investigated by using magic angle spinning NMR and NMR relaxometry analysis. Water, one of the volatile precursor molecules has shown to play a key role in the final conductivity and stability at the solid-electrolyte interface, as it enhances the temperature range in which the ionic liquid remains mobile. In line with previous studies, water with lowered mobility is found in the silicon matrix. The activation energies of lithium ion transfer probed by NMR relaxometry, however, do not change as function of water content. The increase in bulk mobility of lithium ions under ambient conditions compared to water-less nano-SCE is found to be the origin of the altered conductivity of this material.","diffusivity; ionic conductivity; ionogel; nanoporous silica; nuclear magnetic resonance spectroscopy","en","journal article","","","","","","","","","","","ChemE/Materials for Energy Conversion and Storage","","",""
"uuid:93bb0c4c-2d1f-4999-a5e8-155ceaa96c4b","http://resolver.tudelft.nl/uuid:93bb0c4c-2d1f-4999-a5e8-155ceaa96c4b","Experimental and numerical evaluation of conduction welded thermoplastic composite joints","Tijs, B.H.A.H. (TU Delft Aerospace Structures & Computational Mechanics; Fokker/GKN Aerospace); Doldersum, M.H.J. (TU Delft Externenregistratie; Fokker/GKN Aerospace); Turon, A. (University of Girona); Waleson, J. E.A. (Fokker/GKN Aerospace); Bisagni, C. (TU Delft Aerospace Structures & Computational Mechanics)","","2022","The capability of joining two thermoplastic composite parts by welding is a key technology to reduce the weight and cost of assembled parts and enables high volume manufacturing of future aeronautical structures made of thermoplastic composite materials. However, there is not much experimental understanding of the mechanisms involving welded joint failure, and the computational tools available for the simulation of thermoset composites have not yet been completely assessed for thermoplastic materials. In this work, a numerical and experimental evaluation is performed to investigate the strength and failure behavior of conduction welded thermoplastic composite joints. A welded single lap shear joint is designed, manufactured, tested and analyzed proposing two distinct modeling approaches. A simplified modeling strategy which only accounts for damage at the weld is compared to a high-fidelity model which can take into account the physical failure mechanisms at the lamina level. The high-fidelity modeling methodology is able to predict the experimental failure mode of the investigated welded joints with high accuracy and is used to gain new insights into the key-variables that influence the strength of thermoplastic welded joints. It is also found that the joint strength is highly influenced by the failure mechanisms not only of the welded interface but also of the surrounding plies.","Cohesive failure; Conduction welding; Progressive damage modeling; Single lap shear; Thermoplastic composites; Virtual testing","en","journal article","","","","","","","","","","","Aerospace Structures & Computational Mechanics","","",""
"uuid:af53215c-69ea-4c18-8761-d5cfd2c6e186","http://resolver.tudelft.nl/uuid:af53215c-69ea-4c18-8761-d5cfd2c6e186","Atrial fibrillation fingerprinting","Abdi, Bahareh (TU Delft Signal Processing Systems)","Hendriks, R.C. (promotor); van der Veen, A.J. (promotor); de Groot, N.M.S. (promotor); Delft University of Technology (degree granting institution)","2021","Atrial fibrillation (AF) is a common age-related cardiac arrhythmia. AF is characterized by rapid and irregular electrical activity of the heart leading to a higher risk of stroke and heart failure. During AF, the upper chambers of the heart, called atria, experience chaotic electrical wave propagation. However, despite the various mechanisms introduced in the literature, there is still an ongoing debate on a precise and consistent mechanism underlying the initiation and perpetuation of AF. Some studies show that AF is rooted in impaired electrical conduction and structural damage of atrial tissue, known as electropathology. Atrial electrograms (EGMs) recorded directly from heart’s surface, provide an important diagnostic tool to localize and quantify the degree of electropathology in the tissue. However, the analysis of the electrograms is currently constrained by the lack of suitable methods that can reveal the hidden electrophysiological parameters of the tissue. These parameters can be used as local indication of electropathology in the tissue. We believe that understanding AF and improving AF therapy starts with developing a proper forward model that is accurate enough (from a physiological point of view) and simultaneously simple enough to allow for subsequent parameter estimation. Therefore, the main focus of this thesis is on developing a simplified forward model that can efficiently explain the observed EGM based on AF relevant tissue parameters. An initial step before performing any analysis on the data is to remove noise and artefacts. All atrial electrogram recordings suffer from strong far-field ventricular activities (VA). Therefore, as the first step, we propose a new framework for removal of VA from atrial electrograms, which is based on interpolation and subtraction followed by low-rank and sparse matrix decomposition. The proposed framework is of low complexity, does not require high resolution multi-channel recordings, or a calibration step for each individual patient. In the next step, we develop a simplified electrogram model. We represent the model in a compact matrix form and show its linear dependence on the conductivity vector, enabling the estimation of this parameter from the recorded electrograms. The results show that despite the low resolution and all simplifying assumptions, the model can efficiently estimate the conductivity map and regenerate realistic electrograms, especially during sinus rhythm. In the next contribution of this dissertation, we propose a new approach for a better estimation of local activation times for atrial mapping by reducing the spatial blurring effect that is inherent to electrogram recordings using deconvolution. Employing sparsity based regularization and first-order time derivatives in formulating the deconvolution problem, improved performance of transmembrane current estimation is obtained. In the final part, we focus on translating our findings from research to clinical application. Therefore, we studied the effect of electrode size on electrogram properties including the length of the block line observed on the resulting activation map, percentage of observed low voltage areas, percentage of electrograms with low maximum steepness, and the number of deflections in the recorded electrograms.","atrial fibrillation; atrial electrograms; atrial mapping; fractionation; local activation time estimation; electrogram model; transmembrane current; conductivity estimation; electrophysiological model; inverse problem; reaction-diffusion equation; deconvolution; electrode size; electrogram morphology; activation map; electrogram interpolation","en","doctoral thesis","","978-94-6384-260-0","","","","","","","","","Signal Processing Systems","","",""
"uuid:435021b2-a5bd-4280-aca2-7af8975b9ad9","http://resolver.tudelft.nl/uuid:435021b2-a5bd-4280-aca2-7af8975b9ad9","Influence of the relative molecular mass of viscosity enhancers on chloride diffusion in mortars: a preliminary study","Zhao, Lixiao (Southeast University, China); Feng, Pan (Southeast University, China - State Key laboratory of High Performance Civil Engineering Materials, China)","","2021","Chloride diffusion in concrete is one of the key parameters of durability design for structure. Existing methods of reducing the chloride diffusion such as decreasing water-cement ratio and adding mineral admixtures often lead to increase the risk of concrete cracking. In this study, we focused on mitigating the permeation of chloride ions in concrete by adding viscosity enhancers to improve the viscosity of concrete pore solution, without densifying the pore structure of concrete. A comparative study was conducted among the conductivity of KCl solutions with the addition of polyethylene glycol (PEG) with 11 different relative molecular masses. The results show that the chloride diffusion can be most effectively reduced when the relative molecular mass remains in the range of 400-1500.","Conductivity; Viscosity enhancer; Chloride diffusion; Relative molecular mass","en","conference paper","","","","","","","","","","","","","",""
"uuid:df61c4fc-36bb-4a3b-ab0f-9e0176327c45","http://resolver.tudelft.nl/uuid:df61c4fc-36bb-4a3b-ab0f-9e0176327c45","On intimate relationships between healthcare professionals and patients: a nationwide cohort analysis of medical tribunal decisions in the Netherlands","Rietdijk, Wim (Erasmus MC); Renes, Sander (TU Delft Economics of Technology and Innovation; Erasmus Universiteit Rotterdam)","","2021","Background: We examine the incidence of medical tribunal decisions and disciplinary actions (DAs) against healthcare professionals (HCPs). In addition, we studied whether an intimate relationship between an HCP and patient as part of the medical tribunal decision is associated with an increased likelihood of disciplinary actions. Methods: We conducted a nationwide cohort analysis on the downloadable medical tribunal decisions from a medical disciplinary tribunal in the Netherlands from 2010 to 2017. Results: We found that 117 (2.8%) of the 4,046 medical tribunal decisions involved an alleged intimate relationship between an HCP and patient. In these medical tribunal decisions the likelihood of a disciplinary action was significantly increased (odds ratio [OR] 12.97, 95% Confidence Interval [95% CI] 7.11–23.64). In addition, we found that nurses and psychiatrists are more frequently accused of and receive disciplinary actions due to intimate relationships than other HCP groups. Conclusions: We found a limited number of medical tribunal decisions involving an intimate relationship. Especially given the total number of medical tribunal decisions and the number of yearly HCP-patient interactions, the number appears small. Furthermore, an alleged intimate relationship or inappropriate sexual conduct is associated with an increased likelihood of disciplinary action. Future research should obtain statistics on the number of intimate relationships that actually start between HCPs and patients.","Inappropriate sexual conduct; Medical disciplinary actions; Medical doctors & healthcare professionals; Professional behavior","en","journal article","","","","","","","","","","","Economics of Technology and Innovation","","",""
"uuid:08e16a9e-e8f7-41a1-be55-aa1285a6ecdf","http://resolver.tudelft.nl/uuid:08e16a9e-e8f7-41a1-be55-aa1285a6ecdf","Analytical model for arbitrarily configured neighboring shallow geothermal installations in the presence of groundwater flow","Al-Khoury, Rafid (TU Delft Applied Mechanics); BniLam, Noori (Universiteit Antwerpen); Musivand Arzanfudi, M. (TU Delft Applied Mechanics; DIANA FEA); Saeid, S. (TU Delft Reservoir Engineering)","","2021","This paper introduces an analytical model analyzing the effect of groundwater flow on heat transfer in an infinite conductive-convective porous domain representing shallow geothermal systems with arbitrarily configured cylindrical heat sources. The model is formulated based on the moving source concept and solved based on the spectral analysis method and the superposition principle. Compared to models based on the Green's function and the Laplace transform, the proposed spectral model has a simpler formulation, computationally efficient and easy to implement in computer codes. It can handle random time-dependent thermal loads and any arbitrarily configured grid distribution. The verification and numerical examples demonstrate the computational capabilities of the model, and show how the groundwater flow can play an important role in the thermal interaction between heat sources. They also feature how to make use of the direction of groundwater flow to avoid undesirable thermal interaction between neighboring installations, rapid depletion of energy sources and unfair mining of geothermal energy.","Conduction-convection heat flow; Heat flow due to groundwater; Moving cylindrical heat source; Neighboring ground source heat pump installations","en","journal article","","","","","","","","","","","Applied Mechanics","","",""
"uuid:f11af667-165f-4ee0-bacc-7fccab4913d2","http://resolver.tudelft.nl/uuid:f11af667-165f-4ee0-bacc-7fccab4913d2","Electrical Properties Tomography: A Methodological Review","Leijsen, R.L. (Leiden University Medical Center); Brink-van Caspel, W.M. (Leiden University Medical Center); At Van Den Berg, Cornelis (University Medical Center Utrecht); Webb, A. (TU Delft Signal Processing Systems; Leiden University Medical Center); Remis, R.F. (TU Delft Signal Processing Systems)","","2021","Electrical properties tomography (EPT) is an imaging method that uses a magnetic resonance (MR) system to non-invasively determine the spatial distribution of the conductivity and permittivity of the imaged object. This manuscript starts by providing clear definitions about the data required for, and acquired in, EPT, followed by comprehensively formulating the physical equations underlying a large number of analytical EPT techniques. This thorough mathematical overview of EPT harmonizes several EPT techniques in a single type of formulation and gives insight into how they act on the data and what their data requirements are. Furthermore, the review describes machine learning-based algorithms. Matlab code of several differential and iterative integral methods is available upon request.","Conductivity; Electrical properties tomography (EPT); Inversion; Magnetic resonance imaging (MRI); Permittivity","en","journal article","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:6806ae2e-b357-42e8-91d3-765f3a799560","http://resolver.tudelft.nl/uuid:6806ae2e-b357-42e8-91d3-765f3a799560","Drude Dispersion in the Transmission Line Modeling of Bulk Absorbers at Sub-mm Wave Frequencies: A Tool for Absorber Optimization","van Schelven, R.M. (TU Delft Tera-Hertz Sensing); Fiorellini Bernardis, A. (TU Delft Tera-Hertz Sensing); Sberna, P.M. (TU Delft EKL Processing); Neto, A. (TU Delft Tera-Hertz Sensing)","","2021","Semiconductor (SC)-based bulk absorbers operating in the (sub-) THz range are discussed. The conductivities of the bulk media are described by the Drude model for electron gas where the electron density is controlled. The Drude model predicts the existence of two frequencies of interest: one associated with the scattering time of the electrons and a second associated with the plasma frequency. The dimensions of the absorbers for a specific frequency range can be minimized by tuning the doping levels. Eventually, the maximum ohmic absorption from a bulk material is achieved when the real part of the characteristic impedance of the absorber is matched to the one of the surrounding medium and the imaginary part of the characteristic impedance is high so that the power entering the material is actually transformed in heat. Using a classic transmission line representation, a matching layer is introduced to further increase the absorption capabilities of an SC slab. Measurements using a time-domain spectroscopy (TDS) system show the increased accuracy of the Drude model","Conductivity; Electric fields; Gold; Ions; Lenses; Metals; Silicon","en","journal article","","","","","","","","","","","Tera-Hertz Sensing","","",""
"uuid:6d5f9d17-a586-4026-af07-33d9a1d5fad3","http://resolver.tudelft.nl/uuid:6d5f9d17-a586-4026-af07-33d9a1d5fad3","Synergistic toughening and electrical functionalization of an epoxy using MWCNTs and silane- /plasma-activated basalt fibers","Quan, D. (TU Delft Structural Integrity & Composites); Moloney, Peter (University College Dublin); Carolan, Declan (Imperial College London; FAC Technology); Abourayana, Hisham (University College Dublin); Ralph, Calvin (Ulster University); Ivankovic, Alojz (University College Dublin); Dowling, Denis (University College Dublin); Murphy, Neal (University College Dublin)","","2021","This work studied the effects of adding short basalt fibers (BFs) and multi-walled carbon nanotubes (MWCNTs), both separately and in combination, on the mechanical properties, fracture toughness, and electrical conductivity of an epoxy polymer. The surfaces of the short BFs were either treated using a silane coupling agent or further functionalized by atmospheric plasma to enhance the adhesion between the BFs and the epoxy. The results of a single fiber fragmentation test demonstrated a significantly improved BF/epoxy adhesion upon applying the plasma treatment to the BFs. This resulted in better mechanical properties and fracture toughness of the composites containing the plasma-activated BFs. The improved BF/epoxy adhesion also affected the hybrid toughening performance of the BFs and MWCNTs. In particular, synergistic toughening effects were observed when the plasma-activated BFs/MWCNTs hybrid modifiers were used, while only additive toughening effects occurred for the silane-sized BFs/MWCNTs hybrid modifiers. This work demonstrated a potential to develop strong, tough, and electrically conductive epoxy composites by adding hybrid BF/MWCNT modifiers.","applications; conducting polymers; graphene and fullerenes; mechanical properties; microscopy; nanotubes","en","journal article","","","","","","","","2021-07-01","","","Structural Integrity & Composites","","",""
"uuid:c2e211d6-8bea-453c-bd27-601c83f23cec","http://resolver.tudelft.nl/uuid:c2e211d6-8bea-453c-bd27-601c83f23cec","Modeling of multiphase mass and heat transfer in fractured high-enthalpy geothermal systems with advanced discrete fracture methodology","Wang, Y. (TU Delft Reservoir Engineering); de Hoop, S. (TU Delft Applied Geology); Voskov, D.V. (TU Delft Reservoir Engineering; Stanford University); Bruhn, D.F. (TU Delft Reservoir Engineering; German Research Centre for Geosciences); Bertotti, G. (TU Delft Applied Geology)","","2021","Multiphase mass and heat transfer are ubiquitous in the subsurface within manifold applications. The presence of fractures over several scales and complex geometry magnifies the uncertainty of the heat transfer phenomena, which will significantly impact, or even dominate, the dynamic transport process. Capturing the details of fluid and heat transport within the fractured system is beneficial to the subsurface operations. However, accurate modeling methodologies for thermal high-enthalpy multiphase flow within fractured reservoirs are quite limited. In this work, multiphase flow in fractured geothermal reservoirs is numerically investigated. A discrete-fracture model is utilized to describe the fractured system. To characterize the thermal transport process accurately and efficiently, the resolution of discretization is necessarily optimized. A synthetic fracture model is firstly selected to run on different levels of discretization with different initial thermodynamic conditions. A comprehensive analysis is conducted to compare the convergence and computational efficiency of simulations. The numerical scheme is implemented within the Delft Advanced Research Terra Simulator (DARTS), which can provide fast and robust simulation to energy applications in the subsurface. Based on the converged numerical solutions, a thermal Péclet number is defined to characterize the interplay between thermal convection and conduction, which are the two governing mechanisms in geothermal development. Different heat transfer stages are recognized on the Péclet curve in conjunction with production regimes of the synthetic fractured reservoir. A fracture network, sketched and scaled up from a digital map of a realistic outcrop, is then utilized to perform a sensitivity analysis of the key parameters influencing the heat and mass transfer. Thermal propagation and Péclet number are found to be sensitive to flow rate and thermal parameters (e.g., rock heat conductivity and heat capacity). This paper presents a numerical simulation framework for fractured geothermal reservoirs, which provides the necessary procedures for practical investigations regarding geothermal developments with uncertainties.","Discrete-fracture model; High-enthalpy geothermal simulation; Péclet number; Thermal convection and conduction","en","journal article","","","","","","","","","","","Reservoir Engineering","","",""
"uuid:e46381a6-221b-4408-9713-e21abf252d86","http://resolver.tudelft.nl/uuid:e46381a6-221b-4408-9713-e21abf252d86","Conductive compartmented capsules encapsulating a bitumen rejuvenator","Tabakovic, A. (TU Delft Materials and Environment; Dublin Institute of Technology; University College Dublin); Mohan, Joseph (Dublin Institute of Technology); Karač, Aleksandar (University of Zenica)","","2021","This paper explores the potential use of conductive alginate capsules encapsulating a bitumen rejuvenator as a new extrinsic self-healing asphalt method. The capsules combine two existing self-healing asphalt technologies: (1) rejuvenator encapsulation and (2) induction heating to create a self-healing system that will provide rapid and effective asphalt pavement repair. The work presents a proof of concept for the encapsulation process, which involves embedding the capsules into the bitumen mortar mixture and the survival rate of the capsules in the asphalt mixture. A drip capsule production process was adopted and scaled up to the production of 20l wet capsules at rate of 0.22 l/min. To prove the effectiveness and its ability to survive asphalt production process, the capsules were prepared and subjected to thermogravimetric analysis (TGA) and uniaxial compression Test (UCT). The test results demonstrated that the capsules had suitable thermal characteristics and mechanical strength to survive the asphalt mixing and compaction process. Scanning electron microscopy (SEM) was employed to investigate physiological properties, such as rejuvenator (oil) and iron particle distribution, within the capsules. The electrical resistance tests proved that the capsules were capable of conducting electrical current. The capsules were also tested for their conductive properties in order to determine whether they are capable of conducting and distributing the heat once subjected to induction heating. The results showed that capsules containing higher amounts of iron (alginate/iron powder in a ratio of 20:80 by weight) can efficiently conduct and distribute heat. To prove its success as an asphalt healing system, conductive alginate capsules encapsulating a bitumen rejuvenator were embedded in a bitumen mortar mix. The samples where then subjected to local damaging and healing events, and the degree of healing was quantified. The research findings indicate that conductive alginate capsules encapsulating a bitumen rejuvenator present a promising new approach for the development of an extrinsic self-healing asphalt pavement systems.","Alginate; Bitumen healing; Conductive alginate capsules; Conductivity; Induction heating; Rejuvenation; Self-healing","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:9a085bcc-4f35-411e-b5cd-f2b67c5ab403","http://resolver.tudelft.nl/uuid:9a085bcc-4f35-411e-b5cd-f2b67c5ab403","Influence of Reduced Na Vacancy Concentrations in the Sodium Superionic Conductors Na11+ xSn2P1- xMxS12(M = Sn, Ge)","Kraft, Marvin A. (University of Münster); Gronych, Lara M. (University of Münster); Famprikis, T. (TU Delft RST/Storage of Electrochemical Energy); Zeier, Wolfgang G. (University of Münster; FZ Jülich)","","2021","Exploration of sulfidic sodium solid electrolytes and their design contributes to advances in solid-state sodium batteries. Such a design is guided by a better understanding of fast sodium transport, for instance, in the herein studied Na11Sn2PS12-type materials. By using Rietveld refinements against synchrotron X-ray diffraction and electrochemical impedance spectroscopy, the influence of aliovalent substitution on the structure and transport in Na11+xSn2P1-xMxS12 with M = Ge and Sn is investigated. Although Sn induces stronger structural changes than Ge, the influence on the sodium sublattice and the ionic transport properties is comparable. Overall, a reduced in-grain activation energy of Na+ transport can be found with the reducing Na+ vacancy concentration. This work explores previously unreported phases in the Na11Sn2PS12 structure type based on their determined properties revealing Na+ vacancy concentrations to be an important factor providing a further understanding of Na11Sn2PS12-type materials.","ion conduction; sodium solid electrolyte; solid-state battery; structure-transport relationships; vacancy concentration; X-ray diffraction","en","journal article","","","","","","Accepted Author Manuscript","","2022-07-02","","","RST/Storage of Electrochemical Energy","","",""
"uuid:de23fda9-d4a0-4130-ab41-a46ba29b2c0e","http://resolver.tudelft.nl/uuid:de23fda9-d4a0-4130-ab41-a46ba29b2c0e","FE2 multi-scale framework for the two-equation model of transient heat conduction in two-phase media","Zhuo, M. (TU Delft Applied Mechanics; Imperial College London)","","2021","In the study of transient heat conduction in heterogeneous two-phase media, the local thermal non-equilibrium condition calls for the use of a two-equation model to appropriately describe different temperatures in the two phases. We propose for the two-equation model an FE2 multi-scale framework that is capable of addressing nonlinear conduction problems. The FE2 framework consists of volume-averaged macroscale equations, well-defined microscale problems, and the information exchange between the two scales. Compared to a traditional FE2 method for the one-equation model, the proposed FE2 framework introduces an additional source term at the macroscale that is upscaled from the microscale interfacial heat transfer. At variance with the tangent matrices (i.e., effective conductivity) of the heat flux, the tangent matrices of the interfacial heat transfer depend on the microscopic length scale. The proposed FE2 framework is validated against single-scale direct numerical simulations, and some numerical examples are employed to demonstrate its potential.","computational homogenization; FE method; interfacial heat transfer; transient heat conduction; two-equation model","en","journal article","","","","","","","","","","","Applied Mechanics","","",""
"uuid:bb534906-a383-47a5-b100-31d9f01c8b3a","http://resolver.tudelft.nl/uuid:bb534906-a383-47a5-b100-31d9f01c8b3a","Cardiac tissue conductivity estimation using confirmatory factor analysis","Sun, M. (TU Delft Signal Processing Systems); de Groot, N.M.S. (Erasmus MC); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2021","Impaired electrical conduction has been shown to play an important role in the development of heart rhythm disorders. Being able to determine the conductivity is important to localize the arrhythmogenic substrate that causes abnormalities in atrial tissue. In this work, we present an algorithm to estimate the conductivity from epicardial electrograms (EGMs) using a high-resolution electrode array. With these arrays, it is possible to measure the propagation of the extracellular potential of the cardiac tissue at multiple positions simultaneously. Given this data, it is in principle possible to estimate the tissue conductivity. However, this is an ill-posed problem due to the large number of unknown parameters in the electrophysiological data model. In this paper, we make use of an effective method called confirmatory factor analysis (CFA), which we apply to the cross correlation matrix of the data to estimate the tissue conductivity. CFA comes with identifiability conditions that need to be satisfied to solve the problem, which is, in this case, estimation of the tissue conductivity. These identifiability conditions can be used to find the relationship between the desired resolution and the required amount of data. Numerical experiments on the simulated data demonstrate that the proposed method can localize the conduction blocks in the tissue and can also estimate the smoother variation in the conductivities. The conductivity values estimated from the clinical data are in line with the values reported in literature and the EGMs reconstructed based on the estimated parameters match well with the clinical EGMs.","Conduction block; Conductivity estimation; Confirmatory factor analysis; Cross power spectral density; Epicardial electrograms","en","journal article","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:04af6844-5394-4339-a9a1-bd808aa24cc9","http://resolver.tudelft.nl/uuid:04af6844-5394-4339-a9a1-bd808aa24cc9","A Method to Experimentally Estimate the Conductivity of Chronic Stroke Lesions: A Tool to Individualize Transcranial Electric Stimulation","van der Cruijsen, J. (TU Delft Biomechatronics & Human-Machine Control; Erasmus MC); Piastra, Maria Carla (Radboud University Medical Center); Selles, R.W. (Erasmus MC); Oostendorp, Thom F. (Radboud University Medical Center)","","2021","The inconsistent response to transcranial electric stimulation in the stroke population is attributed to, among other factors, unknown effects of stroke lesion conductivity on stimulation strength at the targeted brain areas. Volume conduction models are promising tools to determine optimal stimulation settings. However, stroke lesion conductivity is often not considered in these models as a source of inter-subject variability. The goal of this study is to propose a method that combines MRI, EEG, and transcranial stimulation to estimate the conductivity of cortical stroke lesions experimentally. In this simulation study, lesion conductivity was estimated from scalp potentials during transcranial electric stimulation in 12 chronic stroke patients. To do so, first, we determined the stimulation configuration where scalp potentials are maximally affected by the lesion. Then, we calculated scalp potentials in a model with a fixed lesion conductivity and a model with a randomly assigned conductivity. To estimate the lesion conductivity, we minimized the error between the two models by varying the conductivity in the second model. Finally, to reflect realistic experimental conditions, we test the effect rotation of measurement electrode orientation and the effect of the number of electrodes used. We found that the algorithm converged to the correct lesion conductivity value when noise on the electrode positions was absent for all lesions. Conductivity estimation error was below 5% with realistic electrode coregistration errors of 0.1° for lesions larger than 50 ml. Higher lesion conductivities and lesion volumes were associated with smaller estimation errors. In conclusion, this method can experimentally estimate stroke lesion conductivity, improving the accuracy of volume conductor models of stroke patients and potentially leading to more effective transcranial electric stimulation configurations for this population.","bioimpedance; conductivity measurement; electroencephalography; stroke lesion; tDCS","en","journal article","","","","","","","","","","","Biomechatronics & Human-Machine Control","","",""
"uuid:8c8432c0-8e2e-4de3-aa6d-6c27210d36ea","http://resolver.tudelft.nl/uuid:8c8432c0-8e2e-4de3-aa6d-6c27210d36ea","Hydrodynamics for the partial exclusion process in random environment","Floreani, S. (TU Delft Applied Probability); Redig, F.H.J. (TU Delft Applied Probability); Sau, Federico (Institute of Science and Technology (IST Austria))","","2021","In this paper, we introduce a random environment for the exclusion process in Zd obtained by assigning a maximal occupancy to each site. This maximal occupancy is allowed to randomly vary among sites, and partial exclusion occurs. Under the assumption of ergodicity under translation and uniform ellipticity of the environment, we derive a quenched hydrodynamic limit in path space by strengthening the mild solution approach initiated in Nagy (2002) and Faggionato (2007). To this purpose, we prove, employing the technology developed for the random conductance model, a homogenization result in the form of an arbitrary starting point quenched invariance principle for a single particle in the same environment, which is a result of independent interest. The self-duality property of the partial exclusion process allows us to transfer this homogenization result to the particle system and, then, apply the tightness criterion in Redig et al. (2020).","Arbitrary starting point quenched invariance principle; Duality; Hydrodynamic limit; Mild solution; Random conductance model; Random environment","en","journal article","","","","","","","","","","","Applied Probability","","",""
"uuid:bb9d127f-098a-464c-83a1-9c372a003ade","http://resolver.tudelft.nl/uuid:bb9d127f-098a-464c-83a1-9c372a003ade","ASH: an Automatic pipeline to generate realistic and individualized chronic Stroke volume conduction Head models","Piastra, Maria Carla (Radboud University Medical Center); van der Cruijsen, J. (Erasmus MC); Piai, Vitória (Radboud University Medical Center); Jeukens, Floor E.M. (Student TU Delft); Manoochehri, M. (TU Delft Biomechatronics & Human-Machine Control); Schouten, A.C. (TU Delft Biomechatronics & Human-Machine Control; University of Twente); Selles, R.W. (Erasmus MC); Oostendorp, Thom (Radboud University Medical Center)","","2021","Objective. Large structural brain changes, such as chronic stroke lesions, alter the current pathways throughout the patients' head and therefore have to be taken into account when performing transcranial direct current stimulation simulations. Approach. We implement, test and distribute the first MATLAB pipeline that automatically generates realistic and individualized volume conduction head models of chronic stroke patients, by combining the already existing software SimNIBS, for the mesh generation, and lesion identification with neighborhood data analysis, for the lesion identification. To highlight the impact of our pipeline, we investigated the sensitivity of the electric field distribution to the lesion location and lesion conductivity in 16 stroke patients' datasets. Main results. Our pipeline automatically generates 1 mm-resolution tetrahedral meshes including the lesion compartment in less than three hours. Moreover, for large lesions, we found a high sensitivity of the electric field distribution to the lesion conductivity value and location. Significance. This work facilitates optimizing electrode configurations with the goal to obtain more focal brain stimulations of the target volumes in rehabilitation for chronic stroke patients.","Automatic pipeline; Chronic stroke; Lesion conductivity; Motor rehabilitation; Tdcs; Volume conduction head model","en","journal article","","","","","","","","","","","Biomechatronics & Human-Machine Control","","",""
"uuid:bf8763a2-2d22-48e0-8a55-68104675d240","http://resolver.tudelft.nl/uuid:bf8763a2-2d22-48e0-8a55-68104675d240","A high pressure die cast magnesium alloy with superior thermal conductivity and high strength","Rong, Jian (Beihang University); Zhu, Jia-Ning (TU Delft Team Vera Popovich); Xiao, Wenlong (Beihang University); Zhao, Xinqing (Beihang University); Ma, Chaoli (Beihang University)","","2021","Thermal conductivity is a key parameter for high performance material needed for electronic devices. While most commercially used Mg foundry alloys exhibit low thermal conductivities. In this work, we developed an Mg–3RE–0.5Zn alloy that is suitable for high pressure die cast (HPDC) ultrathin wall cellphone components. The thermal conductivity of this alloy was measured to be 133.9 W/(m·K) at room temperature, approximately 85% that of pure Mg (156 W/(m·K)). Meanwhile, it exhibited acceptable room-temperature mechanical properties with high yield strength of ∼153 MPa, ultimate tensile strength of ∼195 MPa, and elongation of ∼4.3%. The excellent combination of superior thermal conductivity and high strength is attributed to low solute atoms in the α-Mg matrix and the formation of networked (Mg, Zn)12RE eutectic phase. The results from this study will be helpful for developing new HPDC Mg alloys with more excellent performances and promoting the wider application of Mg alloys.","High pressure die casting; Magnesium alloys; Mechanical properties; Microstructure; Thermal conductivity","en","journal article","","","","","","Accepted Author Manuscript","","2023-09-11","","","Team Vera Popovich","","",""
"uuid:fb64487a-2142-48db-beca-42cb70dcbe55","http://resolver.tudelft.nl/uuid:fb64487a-2142-48db-beca-42cb70dcbe55","How Deep Hole Traps Affect the Charge Dynamics and Collection in Bare and Bilayers of Methylammonium Lead Bromide","Zhao, J. (TU Delft ChemE/Opto-electronic Materials); Caselli, V.M. (TU Delft ChemE/Opto-electronic Materials); Bus, M. (TU Delft ChemE/O&O groep); Boshuizen, B. (TU Delft ChemE/O&O groep); Savenije, T.J. (TU Delft ChemE/Opto-electronic Materials)","","2021","Wide-band-gap perovskites such as methylammonium lead bromide (MAPB) are promising materials for tandem solar cells because of their potentially high open-circuit voltage, which is yet still far below the maximum limit. The relatively short charge-carrier lifetimes deduced from time-resolved photoluminescence (TRPL) measurements seem in strong contrast with the long lifetimes observed with time-resolved photoconductance measurements. This is explained by a large amount of hole defect states, NT > 1016 cm-3, in spin-coated layers of MAPB residing at or near the grain boundaries. The introduction of hypophosphorous acid (HPA) increases the average grain size by a factor of 3 and reduces the total concentration of the trap states by a factor of 10. The introduction of HPA also increases the fraction of initially generated holes that undergo charge transfer to the selective contact, Spiro-OMeTAD (SO), by an order of magnitude. In contrast to methylammonium lead iodide (MAPI)/SO bilayers, a reduction of the carrier lifetime is observed in MAPB/SO bilayers, which is attributed to the fact that injected holes undergo interfacial recombination via these trap states. Our findings provide valuable insight into the optoelectronic properties of bromide-containing lead halide perovskites essential for designing efficient tandem solar cells.","charge selective contact; charge-carrier dynamics; deep hole traps; metal halide perovskites; time-resolved microwave conductivity","en","journal article","","","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:2e36dd16-6708-4633-acd5-db662ddf7d1f","http://resolver.tudelft.nl/uuid:2e36dd16-6708-4633-acd5-db662ddf7d1f","Thermal conductivity of aqueous solutions of reline, ethaline, and glyceline deep eutectic solvents; a molecular dynamics simulation study","Celebi, A.T. (TU Delft Engineering Thermodynamics); Vlugt, T.J.H. (TU Delft Engineering Thermodynamics); Moultos, O. (TU Delft Engineering Thermodynamics)","","2021","Accurate knowledge and control of thermal conductivities is central for the efficient design of heat storage and transfer devices working with deep eutectic solvents (DESs). The addition of water is a straightforward and cost-efficient way of tuning many properties of DESs. In this work, the thermal conductivities of aqueous solutions of reline, ethaline, and glyceline are reported for the first time. The non-equilibrium molecular dynamics Müller-Plathe (MP) method was used, along with the well-established GAFF and SPC/E force fields for DESs and water, respectively. We show that thermal conductivities of neat DESs are in excellent agreement with available experimental data. The addition of 25 wt% water results in nearly 2 times higher thermal conductivities in all DESs. A further increase in the fraction of water to 75 wt%, causes an increase in the thermal conductivities of DESs ca. 3 times. This behaviour is mainly due to the change in the microscopic structure of the DESs (i.e. hydrogen bonding) upon the addition of water. Our simulations reveal that thermal conductivities of aqueous DESs do not significantly depend on temperature. We also show that thermal conductivities strongly depend on system-size. System-sizes bigger larger than ca. 5 nm should be used.","aqueous solutions; deep eutectic solvents; molecular dynamics simulation; temperature effects; Thermal conductivity","en","journal article","","","","","","","","","","","Engineering Thermodynamics","","",""
"uuid:5137711f-d5e6-41b6-ac7a-34c6c5e29caf","http://resolver.tudelft.nl/uuid:5137711f-d5e6-41b6-ac7a-34c6c5e29caf","Triplet Dynamics in Crystalline Perylene Diimides","Felter, K.M. (TU Delft ChemE/Opto-electronic Materials)","Grozema, F.C. (promotor); Savenije, T.J. (promotor); Delft University of Technology (degree granting institution)","2020","Conjugated organic materials are interesting for application in opto-electronic devices where they can act as a light absorbing layer, for instance in solar cells or as a light emitting layer in light-emitting diodes. In addition, they can also be used as the semiconducting materials in for instance field-effect transistors. Conjugated organic materials have certain desirable properties that are generally found in organic materials such as light weight, flexibility and cheap processing from solution. A particularly attractive aspects of such materials is that their solid-state properties can be tuned by making changes in the molecular structure by organic synthesis techniques. This also makes it possible to modify the materials so that they exhibit more uncommon processes that may be beneficial for solar cells. Two of such processes, singlet exciton fission (SF) and triplettriplet annihilation upconversion (TTA-UC) are the main subjects of this thesis. The first (SF) is a process in which a singlet excited state, formed by absorption of light, is transformed into a combination of two triplet excited states each with half of the energy. This can, in principle, double the number of electrons that are injected in a solar cell device, and hence double the current from the device. The second (TTA-UC) is the reverse process of SF in which two triplet states with low energy can be combined into a single higher-energy singlet excited state from which an electron can be injected in a solar cells. Exploiting these two processes can in principle lead to considerable improvements in the efficiency of solar cells based on these devices. SF can be exploited to use the excess energy in photons with more than twice the bandgap energy to excite an additional electron. In this way, the excess energy that is otherwise lost as heat, is used to increase the current and therefore the overall energy efficiency of the device. TTA-UC addresses another energy-loss in solar cells, that of photons in the solar spectrum that have a lower energy than the bandgap of the active material of the solar cell. TTA-UC can be used to combined the energy of two of these photons, that are normally not absorbed by the solar cells, to generate a single higher-energy excited state that has sufficient energy to charge separate at an interface. Together, these two processes can address two of the factors that cause major energy losses in solar cells. In order to efficiently exploit these processes, a detailed fundamental understanding of these processes is required, with particular emphasis on the effect of molecular packing in the solid-state as this is the state where they are to be used in devices.","singlet fission; Microwave conductivity; Transient absorption spectroscopy; upconversion; Perylene-diimide molecules; solid state packing","en","doctoral thesis","","978-94-6332-591-2","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:3bca1fbf-2980-4d77-bf87-d252b8d7c862","http://resolver.tudelft.nl/uuid:3bca1fbf-2980-4d77-bf87-d252b8d7c862","Effects of repeated hydraulic loads on microstructure and hydraulic behaviour of a compacted clayey silt","Azizi, Arash (Politecnico di Torino; Durham University); Musso, Guido (Politecnico di Torino); Jommi, C. (TU Delft Geo-engineering; Politecnico di Milano)","","2020","Soils used in earth construction projects are mostly unsaturated, and they undergo frequent drying–wetting cycles (repeated hydraulic loads) due to changes in climatic conditions or variations of the ground water level, particularly at shallow depths. After compaction, changes in water content can significantly influence the hydromechanical response of the construction material, which therefore must be assessed for repeated hydraulic loads. This research investigates the effect of such loads on the microstructure and hydraulic behaviour of a silty soil, typically used in the construction of embankments and dykes, with the aim of providing a better understanding of the consequences of drying–wetting cycles on the response of the material over time. Experimental tests were performed to study the impact of drying–wetting cycles on the water retention, hydraulic conductivity, and fabric of compacted specimens. Fabric changes are documented to take place even without significant volumetric strains, promoting an irreversible increase in the hydraulic conductivity and a reduction in the capacity to retain water compared to the as-compacted soil. The fabric changes are interpreted and quantified by means of a hydromechanical model, which accounts for the evolving pore-size distribution at different structural levels. The proposed model reproduces quite well the microstructural observations, together with the evolution of the water retention behaviour and hydraulic conductivity.","Compacted silt; Drying-wetting cycle; Hydraulic conductivity; Hydromechanical model; Microstructure; Water retention","en","journal article","","","","","","Accepted author manuscript","","","","","Geo-engineering","","",""
"uuid:704e72b8-6b14-4cf1-a931-9c0f93c50152","http://resolver.tudelft.nl/uuid:704e72b8-6b14-4cf1-a931-9c0f93c50152","TU Delft Code of Conduct: Why What Who How","Roeser, S. (TU Delft Ethics & Philosophy of Technology); Copeland, S.M. (TU Delft Ethics & Philosophy of Technology)","","2020","The Code of Conduct gives direction to all members of the TU Delft community on how to act, how to respond to integrity-related issues, and how to maintain a high level of respect for each other, for our world and for the environment.","code of conduct; integrity; TU Delft","en","report","Delft University of Technology","","","","","","","","","","Ethics & Philosophy of Technology","","",""
"uuid:116908a9-7c2c-4fbf-841b-7c143cf80e92","http://resolver.tudelft.nl/uuid:116908a9-7c2c-4fbf-841b-7c143cf80e92","Atomic Layer Deposition of ZnO on InP Quantum Dot Films for Charge Separation, Stabilization, and Solar Cell Formation","Crisp, R.W. (TU Delft ChemE/Opto-electronic Materials); Hashemi, Fatemeh S.M.; Alkemade, J. (TU Delft ChemE/Product and Process Engineering); Kirkwood, N.R.M. (TU Delft ChemE/Opto-electronic Materials); Grimaldi, G. (TU Delft ChemE/Opto-electronic Materials); Kinge, S.S. (Toyota Motor Europe); Siebbeles, L.D.A. (TU Delft ChemE/Opto-electronic Materials); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering); Houtepen, A.J. (TU Delft ChemE/Opto-electronic Materials)","","2020","To improve the stability and carrier mobility of quantum dot (QD) optoelectronic devices, encapsulation or pore infilling processes are advantageous. Atomic layer deposition (ALD) is an ideal technique to infill and overcoat QD films, as it provides excellent control over film growth at the sub-nanometer scale and results in conformal coatings with mild processing conditions. Different thicknesses of crystalline ZnO films deposited on InP QD films are studied with spectrophotometry and time-resolved microwave conductivity measurements. High carrier mobilities of 4 cm2 (V s)−1 and charge separation between the QDs and ZnO are observed. Furthermore, the results confirm that the stability of QD thin films is strongly improved when the inorganic ALD coating is applied. Finally, proof-of-concept photovoltaic devices of InP QD films are demonstrated with an ALD-grown ZnO electron extraction layer.","charge transport; LEDs; p–n junctions; quantum dots; solar cells; time-resolved microwave conductivity","en","journal article","","","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:eb69b333-ed5c-47a5-874d-6f0ebdebad27","http://resolver.tudelft.nl/uuid:eb69b333-ed5c-47a5-874d-6f0ebdebad27","Impact of Chemically Treated Waste Rubber Tire Aggregates on Mechanical, Durability and Thermal Properties of Concrete","Khern, Yih Chen (Monash University Malaysia); Paul, Suvash Chandra (Monash University Malaysia; International University of Business Agriculture and Technology); Kong, Sih Ying (Monash University Malaysia); Babafemi, Adewumi John (Stellenbosch University); Anggraini, Vivi (Monash University Malaysia); Miah, Md Jihad (University of Asia Pacific); Šavija, B. (TU Delft Materials and Environment)","","2020","Studies have shown that the incorporation of waste tire rubber aggregates reduces the strength, increases permeability and decrease thermal conductivity of concrete. However, only a few studies have investigated the effect of surface-modified rubber aggregates on the properties of concrete. This study investigates the effect of the surface treatment of waste tire rubber as coarse aggregates with different oxidizing solutions and different treatment durations on the mechanical, durability and thermal properties of concrete. The properties of concrete incorporated with 8% rubber coarse aggregates (by volume of natural aggregates) which were treated with three different solutions: water (H2O), 20% sodium hydroxide (NaOH) and 5% calcium hypochlorite [Ca(ClO)2] (both as% weight of water) for durations of 2, 24, and 72 h, respectively. The effect of these treatments on the compressive strength, splitting tensile strength, water permeability, thermal conductivity and diffusivity of concrete was investigated. Results show that Ca(ClO)2 has a more positive effect on the strength and permeability compared to NaOH solution and water. Experimental results were statistically analyzed using ANOVA and Post Hoc tests. The analyses showed that the improvement of concrete strength is only significant when the treatment with NaOH and Ca(ClO)2 is prolonged to 72 h. Furthermore, the microstructural analysis of concrete showed that the improvement in the strength is due to the improved bonding between cement paste and rubber aggregates as a result of surface treatment. This microstructural improvement also resulted in lower water permeability of concrete. However, the thermal conductivity and diffusivity increased when the surface treatment duration increases as there are less air voids in the samples. This study shows that, with appropriate pretreatment, a certain percentage of natural aggregates can be safely replaced with waste tire rubber aggregates while maintaining sufficient quality of the resulting concrete.","ANOVA; mechanical strength; thermal conductivity; waste rubber; water permeability","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:97c14f1b-50a1-4e67-a048-b4262c6248bb","http://resolver.tudelft.nl/uuid:97c14f1b-50a1-4e67-a048-b4262c6248bb","CPT correlations for thermal properties of soils","Vardon, P.J. (TU Delft Geo-engineering); Peuchen, J. (Fugro)","","2020","Obtaining in situ thermal properties of soils is often difficult and time-consuming. Here, cone penetration test (CPT) correlations are proposed and validated for thermal properties of saturated ground, i.e. thermal conductivity and volumetric heat capacity, giving continuous profiles of the parameters, in a substantially reduced time. The proposed correlations utilise the characteristics of existing CPT correlations. The volumetric heat capacity correlations show good agreement with laboratory hot disc tests, and the thermal conductivity correlations proved successful for a range of soil types, including organic soils, clays and sands, although with a reasonable scatter. Empirical adjustment was required for the thermal conductivity of soils showing high (normalised) cone resistance. Utilising thermal CPT (T-CPT)-derived thermal conductivity point values in conjunction with the thermal conductivity correlations offers accurate and continuous site-specific profiles.","Correlations; CPT; Heat capacity; Thermal conductivity","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:85ee5665-0cb3-4d58-9130-768f5c5a63c1","http://resolver.tudelft.nl/uuid:85ee5665-0cb3-4d58-9130-768f5c5a63c1","A novel sweat rate and conductivity sensor patch made with low-cost fabrication techniques","Steijlen, A.S.M. (TU Delft Electronic Instrumentation); Bastemeijer, J. (TU Delft Electronic Instrumentation); Jansen, K.M.B. (TU Delft Emerging Materials); French, P.J. (TU Delft Bio-Electronics); Bossche, A. (TU Delft Electronic Instrumentation)","","2020","Sweat sensor patches offer new opportunities for unobtrusive monitoring of an athlete’s physical status. This paper presents a novel sweat rate and sweat conductivity patch that is easy to prototype and can be made with common low-cost production techniques: laser cutting and standard printed circuit board (PCB) manufacturing. The device consists of a patch made from hydrophilic PET foil, a double-sided adhesive and a thin PCB with gold electrodes. Two electrodes, which are continuously in contact with the inflowing fluid, measure the sweat conductivity and a separate system with interdigitated electrodes measures the filling process of the reservoirs. Impedance measurement results of both systems demonstrate the working of the concept.","Conductivity sensor; Sweat patch; Sweat rate sensor","en","conference paper","IEEE","","","","","Accepted author manuscript","","","","","Electronic Instrumentation","","",""
"uuid:1d0a68f8-4595-4490-a19c-e66546f115cd","http://resolver.tudelft.nl/uuid:1d0a68f8-4595-4490-a19c-e66546f115cd","Performance evaluation of knitted and stitched textile strain sensors","Jansen, K.M.B. (TU Delft Emerging Materials)","","2020","By embedding conductive yarns in, or onto, knitted textile fabrics, simple but robust stretch sensor garments can be manufactured. In that way resistance based sensors can be fully integrated in textiles without compromising wearing comfort, stretchiness, washability, and ease of use in daily life. The many studies on such textile strain sensors that have been published in recent years show that these sensors work in principle, but closer inspection reveals that many of them still have severe practical limitations like a too narrow working range, lack of sensitivity, and undesired time-dependent and hysteresis effects. For those that intend to use this technology it is difficult to determine which manufacturing parameters, shape, stitch type, and materials to apply to realize a functional sensor for a given application. This paper therefore aims to serve as a guideline for the fashion designers, electronic engineers, textile researchers, movement scientists, and human–computer interaction specialists planning to create stretch sensor garments. The paper is limited to textile based sensors that can be constructed using commercially available conductive yarns and existing knitting and embroidery equipment. Within this subtopic, relevant literature is discussed, and a detailed quantitative comparison is provided focusing on sensor characteristics like the gauge factor, working range, and hysteresis.","Conductive yarns; Knitted sensor; Performance evaluation; Stitched sensor; Textile strain sensors","en","review","","","","","","","","","","","Emerging Materials","","",""
"uuid:5df198c5-60cb-4bda-9143-53419c55e086","http://resolver.tudelft.nl/uuid:5df198c5-60cb-4bda-9143-53419c55e086","Scalable Route to Electroactive and Light Active Perylene Diimide Dye Polymer Binder for Lithium-Ion Batteries","Ranque, P.G. (TU Delft OLD ChemE/Organic Materials and Interfaces; Université de Pau et des Pays de l'Adour); George, C. (TU Delft RST/Storage of Electrochemical Energy; Imperial College London); Dubey, R. (TU Delft ChemE/Opto-electronic Materials); van der Jagt, R. (TU Delft RST/Storage of Electrochemical Energy); Flahaut, Delphine (Université de Pau et des Pays de l'Adour); Fehse, M. (TU Delft RST/Storage of Electrochemical Energy; Dutch-Belgian (DUBBLE); European Synchrotron Radiation Facility); Jager, W.F. (TU Delft ChemE/Advanced Soft Matter); Sudhölter, Ernst J. R. (TU Delft ChemE/Advanced Soft Matter); Kelder, E.M. (TU Delft RST/Storage of Electrochemical Energy)","","2020","Developing multifunctional polymeric binders is key to the design of energy storage technologies with value-added features. We report that a multigram-scale synthesis of perylene diimide polymer (PPDI), from a single batch via polymer analogous reaction route, yields high molecular weight polymers with suitable thermal stability and minimized solubility in electrolytes, potentially leading to improved binding affinity toward electrode particles. Further, it develops strategies for designing copolymers with virtually any desired composition via a subsequent grafting, leading to purpose-built binders. PPDI dye as both binder and electroactive additive in lithium half-cells using lithium iron phosphate exhibits good electrochemical performance.","battery binder; conductive polymer; Li-ion batteries; perylene dye; redox active polymer","en","journal article","","","","","","","","","","","OLD ChemE/Organic Materials and Interfaces","","",""
"uuid:d604b0cc-9f1a-457e-89a5-c3e072cd5dfe","http://resolver.tudelft.nl/uuid:d604b0cc-9f1a-457e-89a5-c3e072cd5dfe","An Ordered and Fail-Safe Electrical Network in Cable Bacteria","Thiruvallur Eachambadi, Raghavendran (University of Hasselt); Bonné, Robin (University of Hasselt); Cornelissen, Rob (University of Hasselt); Hidalgo-Martinez, Silvia (Universiteit Antwerpen); Vangronsveld, Jaco (Maria Curie-Sklodowska University, Lublin); Meysman, F.J.R. (TU Delft BT/Environmental Biotechnology; Universiteit Antwerpen); Valcke, Roland (University of Hasselt); Cleuren, Bart (University of Hasselt); Manca, Jean V. (University of Hasselt)","","2020","Cable bacteria are an emerging class of electroactive organisms that sustain unprecedented long-range electron transport across centimeter-scale distances. The local pathways of the electrical currents in these filamentous microorganisms remain unresolved. Here, the electrical circuitry in a single cable bacterium is visualized with nanoscopic resolution using conductive atomic force microscopy. Combined with perturbation experiments, it is demonstrated that electrical currents are conveyed through a parallel network of conductive fibers embedded in the cell envelope, which are electrically interconnected between adjacent cells. This structural organization provides a fail-safe electrical network for long-distance electron transport in these filamentous microorganisms. The observed electrical circuit architecture is unique in biology and can inspire future technological applications in bioelectronics.","bioelectronics; cable bacteria; conductive AFM; electroactive bacteria","en","journal article","","","","","","","","","","","BT/Environmental Biotechnology","","",""
"uuid:c3ca5357-47f9-4d67-951e-dd3c201472ef","http://resolver.tudelft.nl/uuid:c3ca5357-47f9-4d67-951e-dd3c201472ef","Trapping and Detrapping in Colloidal Perovskite Nanoplatelets: Elucidation and Prevention of Nonradiative Processes through Chemical Treatment","Vonk, Sander J.W. (Universiteit Utrecht); Fridriksson, M.B. (Universiteit Utrecht); Hinterding, Stijn O.M. (Universiteit Utrecht); Mangnus, Mark J.J. (Universiteit Utrecht); Van Swieten, Thomas P. (Universiteit Utrecht); Grozema, F.C. (TU Delft ChemE/Opto-electronic Materials); Rabouw, Freddy T. (Debye Institute); van der Stam, W. (TU Delft ChemE/Opto-electronic Materials)","","2020","Metal-halide perovskite nanocrystals show promise as the future active material in photovoltaics, lighting, and other optoelectronic applications. The appeal of these materials is largely due to the robustness of the optoelectronic properties to structural defects. The photoluminescence quantum yield (PLQY) of most types of perovskite nanocrystals is nevertheless below unity, evidencing the existence of nonradiative charge-carrier decay channels. In this work, we experimentally elucidate the nonradiative pathways in CsPbBr3 nanoplatelets, before and after chemical treatment with PbBr2 that improves the PLQY. A combination of picosecond streak camera and nanosecond time-correlated single-photon counting measurements is used to probe the excited-state dynamics over 6 orders of magnitude in time. We find that up to 40% of the nanoplatelets from a synthesis batch are entirely nonfluorescent and cannot be turned fluorescent through chemical treatment. The other nanoplatelets show fluorescence, but charge-carrier trapping leads to losses that are prevented by chemical treatment. Interestingly, even without chemical treatment, some losses due to trapping are mitigated because trapped carriers spontaneously detrap on nanosecond-to-microsecond timescales. Our analysis shows that multiple nonradiative pathways are active in perovskite nanoplatelets, which are affected differently by chemical treatment with PbBr2. More generally, our work highlights that in-depth studies using a combination of techniques are necessary to understand nonradiative pathways in fluorescent nanocrystals. Such understanding is essential to optimize synthesis and treatment procedures.","Quantum yield; Excitons; Physical chemical processes; Electrical conductivity; Recombination","en","journal article","","","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:13881d67-5316-45fc-b373-bd9b4028fcae","http://resolver.tudelft.nl/uuid:13881d67-5316-45fc-b373-bd9b4028fcae","Active material utilization and capacity of fiber-based battery electrodes","Zhuo, M. (TU Delft Applied Mechanics); Grazioli, D. (TU Delft Applied Mechanics); Simone, A. (TU Delft Applied Mechanics; Università degli Studi di Padova)","","2020","This study presents a three-dimensional computational model to evaluate effective conductivity and capacity of fiber-based battery electrodes. We employ electrodes composed of conductive and active material nanofibers dispersed in an electrolyte matrix. The effective conductivity is calculated by means of an equivalent resistor network model, while capacity evaluation is based on the identification of active material fibers that are accessible to electrons (i.e., those connected with the electronically conductive network). When a constraint is applied to the total fiber content, an optimal active-conductive material ratio is determined that maximizes the active material utilization and the electrode capacity. We also study fiber orientation effects on the electrode electrochemical properties. It is found that fiber orientation has a strong impact on the percolation threshold, and this impact also reflects on the active material utilization: the more the fiber orientation deviates from the ideal isotropic distribution, the lower the utilization of active material fibers. This is of special interest for practical applications where geometrical constraints on fiber orientation arise, as in the case of electrospun fibers deposited on a substrate. The results of this study are therefore meant to give an insight into how a fibrous electrode architecture performs and suggest effective design solutions.","Active material utilization; Fiber orientation effect; Fiber-based composite electrode; Optimal active-conductive material ratio; Resistor network model","en","journal article","","","","","","","","","","","Applied Mechanics","","",""
"uuid:a7f05e8b-cf08-4923-b7a9-05ff817a50fc","http://resolver.tudelft.nl/uuid:a7f05e8b-cf08-4923-b7a9-05ff817a50fc","A spectral model for a moving cylindrical heat source in a conductive-convective domain","Al-Khoury, Rafid (TU Delft Applied Mechanics); Bni Lam, N.H.N. (Universiteit Antwerpen); Musivand Arzanfudi, M. (TU Delft Applied Mechanics; DIANA FEA); Saeid, S. (TU Delft Reservoir Engineering)","","2020","This paper introduces a spectral model for a moving cylindrical heat source in an infinite conductive-convective domain. This physical process occurs in many engineering and technological applications including heat conduction-convection in ground source heat pump systems, where the borehole heat exchangers likely go through layers with groundwater flow. The governing heat equation is solved for Dirichlet and Neumann boundary conditions using the fast Fourier transform for the time domain, and the Fourier series for the spatial domain. A closed form solution based on the modified Bessel functions is obtained for the Dirichlet boundary condition and an integral form for the Neumann boundary condition. Limiting cases of the moving cylindrical heat source to represent a moving line heat source are also derived. Compared to solutions based on the Green's function and the Laplace transform, the spectral model has a simpler form, applicable to complicated time-variant input signals, valid for a wide range of physical parameters and easy to implement in computer codes. The model is verified against the existing infinite line heat source model and a finite element model.","Conduction-convection heat flow; Ground source heat pump; Heat flow in groundwater; Moving cylindrical heat source","en","journal article","","","","","","","","","","","Applied Mechanics","","",""
"uuid:f19a5959-b33a-4672-b6fb-17d303002d8f","http://resolver.tudelft.nl/uuid:f19a5959-b33a-4672-b6fb-17d303002d8f","Graphene Isotope Superlattices with Strongly Diminished Thermal Conductivity for Thermoelectric Applications","Whiteway, Eric (McGill University); Lee, M. (TU Delft QN/Steeneken Lab; McGill University; Kavli institute of nanoscience Delft); Hilke, Michael (McGill University)","","2020","Graphene has a high intrinsic thermal conductivity and a high electron mobility. The thermal conductivity of graphene can be significantly reduced when different carbon isotopes are mixed, which can enhance the performance of thermoelectric devices. Here we synthesize isotopic 12C/13C random mixes and isotope superlattices (SLs) with periods ranging from 46 to 225 nm by chemical vapor deposition. Raman optothermal conductivity measurements of these SL structures show an approximately 50% reduction in thermal conductivity compared to pristine 12C graphene. This average reduction is similar to the random isotope mix. The reduction of the thermal conductivity in the SL is well described by a model of pristine graphene and an additional quasi-one-dimensional periodic interfacial thermal resistance of (2.5 ± 0.5) × 10-11 m2 K W-1 for the 12C/13C boundary. This is consistent with a large anisotropic thermal conductivity in the SL, where the thermal conductivity depends on the orientation of the 12C/13C boundary.","graphene; isotope superlattice; nanostructures; Raman spectroscopy; thermal conductivity; thermoelectric devices","en","journal article","","","","","","Accepted Author Manuscript","","2021-08-18","","","QN/Steeneken Lab","","",""
"uuid:dd7e6a5a-561c-40d1-8411-596fdd80ac60","http://resolver.tudelft.nl/uuid:dd7e6a5a-561c-40d1-8411-596fdd80ac60","Realizing the Potential of RF-Sputtered Hydrogenated Fluorine-Doped Indium Oxide as an Electrode Material for Ultrathin SiO x/Poly-Si Passivating Contacts","Han, C. (TU Delft Photovoltaic Materials and Devices); Yang, G. (TU Delft Photovoltaic Materials and Devices); Montes, Ana (University of Lisbon); Procel Moya, P.A. (TU Delft Photovoltaic Materials and Devices); Mazzarella, L. (TU Delft Photovoltaic Materials and Devices); Zhao, Y. (TU Delft Electrical Engineering, Mathematics and Computer Science); Eijt, S.W.H. (TU Delft RST/Fundamental Aspects of Materials and Energy); Schut, H. (TU Delft RST/Neutron and Positron Methods in Materials); Zhang, Xiaodan (Nankai University); Zeman, M. (TU Delft Electrical Sustainable Energy); Isabella, O. (TU Delft Photovoltaic Materials and Devices)","","2020","In high-efficiency silicon solar cells featuring carrier-selective passivating contacts based on ultrathin SiOx/poly-Si, the appropriate implementation of transparent conductive oxide (TCO) layers is of vital importance. Considerable deterioration in passivation quality occurs for thin poly-Si-based devices owing to the sputtering damage during TCO deposition. Curing treatment at temperatures above 350 °C can recover such degradation, whereas the opto-electrical properties of the TCO are affected as well, and the carrier transport at the poly-Si/TCO contact is widely reported to degrade severely in such a procedure. Here, we propose straightforward approaches, post-deposition annealing at 400 °C in nitrogen, hydrogen, or air ambience, are proposed to tailor material properties of high-mobility hydrogenated fluorine-doped indium oxide (IFO:H) film. Structural, morphological, and opto-electrical properties of the IFO:H films are investigated as well as their inherent electron scattering and doping mechanisms. Hydrogen annealing treatment proves to be the most promising strategy. The resulting layer exhibits both optimal opto-electrical properties (carrier density = 1.5 × 1020 cm-3, electron mobility = 108 cm2 V-1 s-1, and resistivity = 3.9 × 10-4 ω cm) and remarkably low contact resistivities (∼20 mω cm2 for both n- and p-contacts) in poly-Si solar cells. Even though the presented cells are limited by the metallization step, the obtained IFO:H-base solar cell show an efficiency improvement from 20.1 to 20.6% after specific hydrogen treatment, demonstrating the potential of material manipulation and contact engineering strategy in high-efficiency photovoltaic devices endowed with TCOs.","carrier-selective passivating contacts; hydrogen annealing; hydrogenated fluorine-doped indium oxide (IFO:H); transparent conductive oxide (TCO); ultrathin SiO /poly-Si passivating contacts","en","journal article","","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Electrical Sustainable Energy","Photovoltaic Materials and Devices","","",""
"uuid:ab85d4b0-1ea9-4035-bc00-9a1ea5809ee5","http://resolver.tudelft.nl/uuid:ab85d4b0-1ea9-4035-bc00-9a1ea5809ee5","Impact of green roofs on energy demand for cooling in Egyptian buildings","Ragab, Ayman (Aswan University, Aswan); Abdelrady, Ahmed (TU Delft Water Resources; TU Delft Sanitary Engineering)","","2020","Energy consumption for cooling purposes has increased significantly in recent years, mainly due to population growth, urbanization, and climate change consequences. The situation can be mitigated by passive climate solutions to reduce energy consumption in buildings. This study investigated the effectiveness of the green roof concept in reducing energy demand for cooling in different climatic regions. The impact of several types of green roofing of varying thermal conductivity and soil depth on energy consumption for cooling school buildings in Egypt was examined. In a co-simulation approach, the efficiency of the proposed green roof types was evaluated using the Design-Builder software, and a cost analysis was performed for the best options. The results showed that the proposed green roof types saved between 31.61 and 39.74% of energy, on average. A green roof featuring a roof soil depth of 0.1 m and 0.9 W/m-K thermal conductivity exhibited higher efficiency in reducing energy than the other options tested. The decrease in air temperature due to green roofs in hot arid areas, which exceeded an average of 4 °C, was greater than that in other regions that were not as hot. In conclusion, green roofs were shown to be efficient in reducing energy consumption as compared with traditional roofs, especially in hot arid climates.","Design-Builder; Energy consumption; Green roofs; Thermal conductivity","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:cbb482a0-6443-49a5-aef9-05cafe0f74be","http://resolver.tudelft.nl/uuid:cbb482a0-6443-49a5-aef9-05cafe0f74be","Transparency in Responsible Design: Avoiding Engineering Overconfidence and Supporting Societal Acceptance","Vermaas, P.E. (TU Delft Ethics & Philosophy of Technology)","","2019","In this contribution it is argued that in responsible design engineers should be transparent towards stakeholders about the goals they intend to realise with their designs. The emergence of responsible design in, e.g., value-sensitive design, design for values, social design, nudging and positive design, is to be welcomed. It has however the weakness of overconfidence which may lead engineers to suspend earlier commitments to society as given in engineering codes of conduct and ethics, and practices of seeking informed consent and taking blame. It is argued that these earlier commitments lead to the requirement that engineers should be transparent about the goals in responsible designs. Providing this transparency support moreover the societal acceptance of responsible design since it positions engineers doing responsible design as subscribing to values such as respect, honesty and trust. I illustrate the argument with a case of social design and a case of nudging.","Communication; Engineering codes of conduct; Ethics; Social responsibility; Transparancy","en","conference paper","","","","","","","","","","","Ethics & Philosophy of Technology","","",""
"uuid:71577764-537d-48d2-91ad-e8e792cf7801","http://resolver.tudelft.nl/uuid:71577764-537d-48d2-91ad-e8e792cf7801","Mean-field avalanche size exponent for sandpiles on Galton–Watson trees","Jarai, Antal A. (University of Bath); Ruszel, W.M. (TU Delft Applied Probability; Universiteit Utrecht); Saada, Ellen (Université Paris Descartes)","","2019","We show that in Abelian sandpiles on infinite Galton–Watson trees, the probability that the total avalanche has more than t topplings decays as t- 1 / 2. We prove both quenched and annealed bounds, under suitable moment conditions. Our proofs are based on an analysis of the conductance martingale of Morris (Probab Theory Relat Fields 125:259–265, 2003), that was previously used by Lyons et al. (Electron J Probab 13(58):1702–1725, 2008) to study uniform spanning forests on Zd, d≥ 3 , and other transient graphs.","Abelian sandpile; Conductance martingale; Uniform spanning tree; Wired spanning forest","en","journal article","","","","","","","","","","","Applied Probability","","",""
"uuid:2bfc63f4-52f4-4109-a501-14531d5445f5","http://resolver.tudelft.nl/uuid:2bfc63f4-52f4-4109-a501-14531d5445f5","Effect of tungsten based coating characteristics on microstructure and thermal conductivity of diamond/Cu composites prepared by pressueless infiltration","Jia, Jinhao (National University of Defense Technology); Bai, Shuxin (National University of Defense Technology); Xiong, Degan (National University of Defense Technology); Wang, Jie (Student TU Delft); Chang, J. (TU Delft ImPhys/Optics)","","2019","Tungsten coatings were deposited on diamond particles by vacuum magnetron sputtering. The coated diamond particles were firstly heat treated at different temperatures, and diamond/copper (Cu) composites were fabricated by using a pressureless infiltration method afterwards. The influences of heat treatment on the microstructure and composition of tungsten based coating surface and diamond/copper composites were analysed. Notable differences were found in the microstructure with heating temperatures. Moreover, the tungsten based coating surface contained large quantities of oxidised tungsten, and the phase composition of the coatings varied within the range of tungsten–W 2 C–WC as the heat treatment temperature increased. The fracture surface morphologies in the copper matrix composites reinforced with diamond particles with coatings were identically characterised with the presence of ductile fracture of matrix accompanied by dissociation of diamond particles from the matrix. The thermal conductivity (TC) and gas tightness behaviours of the diamond/copper composites were also explored. A maximum TC of 768 W m −1 K −1 and a fine gas tightness of 2.5 × 10-10 Pa m 3 /s were obtained with reinforcement of tungsten-coated diamond particles treated at 800 °C. The value of the interface thermal resistance between copper and diamond particles was also estimated and specifically discussed.","Diamond/Cu composites; Heat treatment; Thermal conductivity; Tungsten coating","en","journal article","","","","","","Accepted Author Manuscript","","2021-02-25","","","ImPhys/Optics","","",""
"uuid:44dbc6bc-a0fd-4231-b887-88b133ded4d8","http://resolver.tudelft.nl/uuid:44dbc6bc-a0fd-4231-b887-88b133ded4d8","The Need for a Code of Conduct for Research Funders: Commentary on Values in University-Industry Collaborations: The Case of Academics Working at Universities of Technology","van Wee, G.P. (TU Delft Transport and Logistics)","","2019","In addition to a code of conduct for researchers, it is desirable to implement a code of conduct for funders of research. This is because researchers often behave unethically as a result of direct and/or indirect pressure from funders. The paper provides an expansion of the first proposal for such a code of conduct and includes several elements such as “policy relevant research should not be contracted and supervised by a client with an interest in the outcomes”, and “policy relevant research should always be examined by an independent institute”.","Code of conduct; Research; Research ethics; Research funders","en","journal article","","","","","","","","","","","Transport and Logistics","","",""
"uuid:bd8ee049-a1b1-48e7-8c4b-468e9016ffcd","http://resolver.tudelft.nl/uuid:bd8ee049-a1b1-48e7-8c4b-468e9016ffcd","Charge Photogeneration and Transport in AgBiS2 Nanocrystal Films for Photovoltaics","Diedenhofen, S.L. (TU Delft ChemE/Opto-electronic Materials); Bernechea, Maria (Universidad de Zaragoza; Cardiff University); Felter, K.M. (TU Delft ChemE/Opto-electronic Materials); Grozema, F.C. (TU Delft ChemE/Opto-electronic Materials); Siebbeles, L.D.A. (TU Delft ChemE/Opto-electronic Materials)","","2019","Solution-processed AgBiS2 nanocrystal films are a promising material for nontoxic, earth-abundant solar cells. While solar cells with good device efficiency are demonstrated, so far, hardly anything is known about charge generation, transport, and recombination processes in these films. Here, a photoinduced time-resolved microwave conductivity study on AgBiS2 nanocrystal films is presented. By modeling the experimental data with density-dependent recombination processes, the product of the temperature-dependent electron and hole quantum yield and mobility, and the electron and hole recombination kinetics are determined.","AgBiS nanocrystals; charge decay; charge mobility; diffusion length; microwave conductivity","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-10-19","","","ChemE/Opto-electronic Materials","","",""
"uuid:070ec928-5eb7-40dc-9aa8-fd99552acc6a","http://resolver.tudelft.nl/uuid:070ec928-5eb7-40dc-9aa8-fd99552acc6a","Mapping by Observation: Building a User-Tailored Conducting System From Spontaneous Movements","Sarasua, Alvaro (Pompeu Fabra University); Urbano, Julián (TU Delft Multimedia Computing); Gómez, Emilia (Pompeu Fabra University)","","2019","Metaphors are commonly used in interface design within Human-Computer Interaction (HCI). Interface metaphors provide users with a way to interact with the computer that resembles a known activity, giving instantaneous knowledge or intuition about how the interaction works. A widely used one in Digital Musical Instruments (DMIs) is the conductor-orchestra metaphor, where the orchestra is considered as an instrument controlled by the movements of the conductor. We propose a DMI based on the conductor metaphor that allows to control tempo and dynamics and adapts its mapping specifically for each user by observing spontaneous conducting movements (i.e., movements performed on top of fixed music without any instructions). We refer to this as mapping by observation given that, even though the systemis trained specifically for each
user, this training is not done explicitly and consciously by the user. More specifically, the system adapts its mapping based on the tendency of the user to anticipate or fall behind the beat and observing the Motion Capture descriptors that best correlate to loudness during spontaneous conducting. We evaluate the proposed system in an experiment with twenty four (24) participants where we compare it with a baseline that does not perform this user-specific adaptation. The comparison is done in a context where the user does not receive instructions and, instead, is allowed to discover by playing. We evaluate objective and subjective measures from tasks where participants have to make
the orchestra play at different loudness levels or in synchrony with a metronome. Results of the experiment prove that the usability of the system that automatically learns its mapping from spontaneous movements is better both in terms of providing a more intuitive control over loudness and a more precise control over beat timing. Interestingly, the results also show a strong correlation betweenmeasures taken fromthe data used for training and the improvement introduced by the adapting system. This indicates that it is possible to estimate in advance how useful the observation of spontaneous movements is to build user-specific adaptations. This opens interesting directions for creating more
intuitive and expressive DMIs, particularly in public installations.","HCI; digital music; motion-sound mapping; kinect; conducting; machine learning; digital musical instruments","en","journal article","","","","","","","","","","","Multimedia Computing","","",""
"uuid:c4a586f9-18ac-478a-973d-179000dc3401","http://resolver.tudelft.nl/uuid:c4a586f9-18ac-478a-973d-179000dc3401","Characterization of bitumen modified with pyrolytic carbon black from scrap tires","Wang, H. (TU Delft Pavement Engineering); Lu, Guoyang (Rheinisch-Westfälische Technische Hochschule); Feng, Shuyin (University of Bristol); Wen, Xiaobo (JSTI Group); Yang, Jun (Southeast University)","","2019","Pyrolytic carbon black (CB p ) from scrap tire pyrolysis is a potential modifier for the bitumen industry. Binders containing different contents of CB p were prepared and experimentally investigated to examine the effects of CB p on the electrical and thermal conductivity, conventional physical properties, rheological properties, high-temperature antirutting performance, aging resistance, and storage stability. Laboratory test results indicated that the incorporation of CB p effectively improves the electrothermal properties, rheological properties, high-temperature rutting resistance, and aging resistance. It also increases the viscosity and decreases the storage stability of bitumen. The study confirms that CB p -modified bitumen with proper selection of content can be a multifunctional paving material.","Bitumen; Carbon black; Electrical conductivity; Rheological property; Scrap tire pyrolysis; Storage stability","en","journal article","","","","","","","","","","","Pavement Engineering","","",""
"uuid:85dc0984-2fb6-473c-841e-8442bdca36b2","http://resolver.tudelft.nl/uuid:85dc0984-2fb6-473c-841e-8442bdca36b2","Combining deep learning and 3D contrast source inversion in MR-based electrical properties tomography","Leijsen, R.L. (Leiden University Medical Center); van den Berg, Cornelis (University Medical Center Utrecht; Universiteit Utrecht); Webb, A. (Leiden University Medical Center); Remis, R.F. (TU Delft Signal Processing Systems); Mandija, Stefano (University Medical Center Utrecht; Universiteit Utrecht)","","2019","Magnetic resonance electrical properties tomography (MR-EPT) is a technique used to estimate the conductivity and permittivity of tissues from MR measurements of the transmit magnetic field. Different reconstruction methods are available; however, all these methods present several limitations, which hamper the clinical applicability. Standard Helmholtz-based MR-EPT methods are severely affected by noise. Iterative reconstruction methods such as contrast source inversion electrical properties tomography (CSI-EPT) are typically time-consuming and are dependent on their initialization. Deep learning (DL) based methods require a large amount of training data before sufficient generalization can be achieved. Here, we investigate the benefits achievable using a hybrid approach, that is, using MR-EPT or DL-EPT as initialization guesses for standard 3D CSI-EPT. Using realistic electromagnetic simulations at 3 and 7 T, the accuracy and precision of hybrid CSI reconstructions are compared with those of standard 3D CSI-EPT reconstructions. Our results indicate that a hybrid method consisting of an initial DL-EPT reconstruction followed by a 3D CSI-EPT reconstruction would be beneficial. DL-EPT combined with standard 3D CSI-EPT exploits the power of data-driven DL-based EPT reconstructions, while the subsequent CSI-EPT facilitates a better generalization by providing data consistency.","conductivity; contrast source inversion EPT; deep learning EPT; electrical properties tomography; MR-EPT; MRI; permittivity","en","journal article","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:726be36b-9d57-4641-88ca-6179384854f6","http://resolver.tudelft.nl/uuid:726be36b-9d57-4641-88ca-6179384854f6","Model improvements to simulate charging in scanning electron microscope","Arat, K.T. (TU Delft ImPhys/Charged Particle Optics); Klimpel, Thomas (GenISys GmbH); Hagen, C.W. (TU Delft ImPhys/Charged Particle Optics)","","2019","Background: Charging of insulators is a complex phenomenon to simulate since the accuracy of the simulations is very sensitive to the interaction of electrons with matter and electric fields. Aim: In this study, we report model improvements for a previously developed Monte-Carlo simulator to more accurately simulate samples that charge. Approach: The improvements include both modeling of low energy electron scattering by first-principle approaches and charging of insulators by the redistribution of the charge carriers in the material with an electron beam-induced conductivity and a dielectric breakdown model. Results: The first-principle scattering models provide a more realistic charge distribution cloud in the material and a better match between noncharging simulations and experimental results. The improvements on the charging models, which mainly focus on the redistribution of the charge carriers, lead to a smoother distribution of the charges and better experimental agreement of charging simulations. Conclusions: Combined with a more accurate tracing of low energy electrons in the electric field, we managed to reproduce the dynamically changing charging contrast due to an induced positive surface potential.","breakdown; charging; electron beam-induced conductivity; low energy electrons; Monte-Carlo simulation; scanning electron microscope","en","journal article","","","","","","","","","","","ImPhys/Charged Particle Optics","","",""
"uuid:a0a5dd9b-f411-4b25-a5c6-22094fced256","http://resolver.tudelft.nl/uuid:a0a5dd9b-f411-4b25-a5c6-22094fced256","High-Mobility Hydrogenated Fluorine-Doped Indium Oxide Film for Passivating Contacts c-Si Solar Cells","Han, C. (TU Delft Photovoltaic Materials and Devices; Nankai University; Shenzhen Institute of Wide-bandgap Semiconductors); Mazzarella, L. (TU Delft Photovoltaic Materials and Devices); Zhao, Y. (TU Delft Photovoltaic Materials and Devices); Yang, G. (TU Delft Photovoltaic Materials and Devices); Procel Moya, P.A. (TU Delft Photovoltaic Materials and Devices); Tijssen, M. (TU Delft Photovoltaic Materials and Devices); Bento Montes, A.R. (TU Delft Photovoltaic Materials and Devices); Isabella, O. (TU Delft Photovoltaic Materials and Devices); Zeman, M. (TU Delft Electrical Sustainable Energy)","","2019","Broadband transparent conductive oxide layers with high electron mobility (μe) are essential to further enhance crystalline silicon (c-Si) solar cell performances. Although metallic cation-doped In2O3 thin films with high μe (>60 cm2 V-1 s-1) have been extensively investigated, the research regarding anion doping is still under development. In particular, fluorine-doped indium oxide (IFO) shows promising optoelectrical properties; however, they have not been tested on c-Si solar cells with passivating contacts. Here, we investigate the properties of hydrogenated IFO (IFO:H) films processed at low substrate temperature and power density by varying the water vapor pressure during deposition. The optimized IFO:H shows a remarkably high μe of 87 cm2 V-1 s-1, a carrier density of 1.2 × 1020 cm-3, and resistivity of 6.2 × 10-4 ω cm. Then, we analyzed the compositional, structural, and optoelectrical properties of the optimal IFO:H film. The high quality of the layer was confirmed by the low Urbach energy of 197 meV, compared to 444 meV obtained on the reference indium tin oxide. We implemented IFO:H into different front/back-contacted solar cells with passivating contacts processed at high and low temperatures, obtaining a significant short-circuit current gain of 1.53 mA cm-2. The best solar cell shows a conversion efficiency of 21.1%.","electron mobility; hydrogenated fluorine-doped indium oxide (IFO:H); passivating contacts; silicon heterojunction (SHJ); transparent conductive oxide (TCO)","en","journal article","","","","","","green","","","","Electrical Sustainable Energy","Photovoltaic Materials and Devices","","",""
"uuid:680e7b3b-e7e2-4079-ae97-41a027212937","http://resolver.tudelft.nl/uuid:680e7b3b-e7e2-4079-ae97-41a027212937","Interplay between Charge Carrier Mobility, Exciton Diffusion, Crystal Packing, and Charge Separation in Perylene Diimide-Based Heterojunctions","Felter, K.M. (TU Delft ChemE/Opto-electronic Materials); Caselli, V.M. (TU Delft ChemE/Opto-electronic Materials); Gunbas, D.D. (TU Delft ChemE/Opto-electronic Materials); Savenije, T.J. (TU Delft ChemE/Opto-electronic Materials); Grozema, F.C. (TU Delft ChemE/Opto-electronic Materials)","","2019","Two of the key parameters that characterize the usefulness of organic semiconductors for organic or hybrid organic/inorganic solar cells are the mobility of charges and the diffusion length of excitons. Both parameters are strongly related to the supramolecular organization in the material. In this work we have investigated the relation between the solid-state molecular packing and the exciton diffusion length, charge carrier mobility, and charge carrier separation yield using two perylene diimide (PDI) derivatives which differ in their substitution. We have used the time-resolved microwave photoconductivity technique and measured charge carrier mobilities of 0.32 and 0.02 cm2/(Vs) and determined exciton diffusion lengths of 60 and 18 nm for octyl- and bulky hexylheptyl-imide substituted PDIs, respectively. This diffusion length is independent of substrate type and aggregate domain size. The differences in charge carrier mobility and exciton diffusion length clearly reflect the effect of solid-state packing of PDIs on their optoelectronic properties and show that significant improvements can be obtained by effectively controlling the solid-state packing.","charge separation; crystal packing; exciton diffusion length; microwave conductivity; PDI","en","journal article","","","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:d3226d61-7d9f-4c09-aa89-7dcd8824a021","http://resolver.tudelft.nl/uuid:d3226d61-7d9f-4c09-aa89-7dcd8824a021","The contribution of lipid peroxidation to membrane permeability in electropermeabilization: A molecular dynamics study","Rems, L. (TU Delft ChemE/Product and Process Engineering); Viano, Marilyne (Lorraine University); Kasimova, Marina A. (Lorraine University); Miklavčič, Damijan (University of Ljubljana); Tarek, Mounir (Lorraine University)","","2019","Electroporation or electropermeabilization is a technique that enables transient increase in the cell membrane permeability by exposing cells to pulsed electric field. However, the molecular mechanisms of the long-lived cell membrane permeability, which persists on the minutes time scale after the pulse treatment, remain elusive. Experimental studies have suggested that lipid peroxidation could present a mechanism of this prolonged membrane permeabilization. In this study we make the first important step in quantifying the possible contribution of lipid peroxidation to electropermeabilization. We use free energy calculations to quantify the permeability and conductance of bilayers, containing an increasing percentage of hydroperoxide lipid derivatives, to sodium and chloride ions. We then compare our calculations to experimental measurements on electropermeabilized cells. Our results show that the permeability and conductance increase dramatically by several orders of magnitude in peroxidized bilayers. Yet this increase is not sufficient to reasonably account for the entire range of experimental measurements. Nevertheless, lipid peroxidation might be considered an important mechanism of prolonged membrane permeabilization, if exposure of cells to high voltage electric pulses leads to secondary lipid peroxidation products. Our analysis calls for experimental studies, which will determine the type and amount of lipid peroxidation products in electropermeabilized cell membranes.","Cell membrane; Electrical conductance; Electroporation; Free energy calculations; Oxidized lipids; Permeability","en","journal article","","","","","","Accepted Author Manuscript","","2020-09-25","","","ChemE/Product and Process Engineering","","",""
"uuid:1b5ccec1-766e-4e52-b94a-468bf6b1a519","http://resolver.tudelft.nl/uuid:1b5ccec1-766e-4e52-b94a-468bf6b1a519","A compact matrix model for atrial electrograms for tissue conductivity estimation","Abdi, Bahareh (TU Delft Signal Processing Systems); Hendriks, R.C. (TU Delft Signal Processing Systems); van der Veen, A.J. (TU Delft Signal Processing Systems); de Groot, Natasja M.S. (Erasmus MC)","","2019","Finding the hidden parameters of the cardiac electrophysiological model would help to gain more insight on the mechanisms underlying atrial fibrillation, and subsequently, facilitate the diagnosis and treatment of the disease in later stages. In this work, we aim to estimate tissue conductivity from recorded electrograms as an indication of tissue (mal)functioning. To do so, we first develop a simple but effective forward model to replace the computationally intensive reaction-diffusion equations governing the electrical propagation in tissue. Using the simplified model, we present a compact matrix model for electrograms based on conductivity. Subsequently, we exploit the simplicity of the compact model to solve the ill-posed inverse problem of estimating tissue conductivity. The algorithm is demonstrated on simulated data as well as on clinically recorded data. The results show that the model allows to efficiently estimate the conductivity map. In addition, based on the estimated conductivity, realistic electrograms can be regenerated demonstrating the validity of the model.","Atrial fibrillation; Conductivity estimation; Electrode array; Electrograms; Electrophysiological model; Inverse problem; Reaction-diffusion equation","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-08-21","","","Signal Processing Systems","","",""
"uuid:16409a2c-bf1c-4dd3-8f77-030e45630c30","http://resolver.tudelft.nl/uuid:16409a2c-bf1c-4dd3-8f77-030e45630c30","Electronic mobility and crystal structures of 2,5-dimethylanilinium triiodide and tin-based organic-inorganic hybrid compounds","Kamminga, Machteld E. (University Medical Center Groningen); Gelvez Rueda, M.C. (TU Delft ChemE/Opto-electronic Materials); Maheswari, S. (TU Delft ChemE/Opto-electronic Materials); van Droffelaar, I.S. (University Medical Center Groningen); Baas, Jacob (University Medical Center Groningen); Blake, Graeme R. (University Medical Center Groningen); Grozema, F.C. (TU Delft ChemE/Opto-electronic Materials); Palstra, Thomas T.M. (University Medical Center Groningen)","","2019","We synthesize single crystals of a new 2,5-dimethylanilinium tin iodide organic-inorganic hybrid compound and 2,5-dimethylanilinium triiodide. Single-crystal X-ray diffraction reveals that the hybrid grows as a unique rhombohedral structure consisting of one-dimensional chains of SnI6-octahedra that share corners and edges to build up a ribbon along the [111] direction. Notably, we find that hypophosphorous acid, H3PO2, is of central importance to the formation of this hybrid. In the absence of H3PO2, we synthesize 2,5-dimethylanilinium triiodide from the same starting compounds. We investigate the synthesis routes that drive the growth of these two compounds with distinct crystal structures, appearance and properties. Pulse-radiolysis time-resolved microwave conductivity measurements and density functional theory calculations reveal that both compounds have low charge carrier mobilities and very long lifetimes, consistent with their one-dimensional structural characteristics. Our findings give a better understanding of the relation between synthesis, crystal structures and charge carrier mobilities.","Hypophosphorous acid; Microwave conductivity; Organic-organic hybrids; Single-crystal XRD; Tin iodide; Triiodide","en","journal article","","","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:17e7248e-8e1e-42d5-9fba-eac0e08db80e","http://resolver.tudelft.nl/uuid:17e7248e-8e1e-42d5-9fba-eac0e08db80e","Effect of metallic waste addition on the electrical, thermophysical and microwave crack-healing properties of asphalt mixtures","Norambuena-Contreras, J. (University of Bío-Bío); Gonzalez, A. (Pontificia Universidad Católica de Chile); Concha, J. L. (University of Bío-Bío); Gonzalez-Torre, I. (University of Bío-Bío); Schlangen, E. (TU Delft Materials and Environment)","","2018","This paper aims to evaluate the effect of metallic waste addition on the electrical, thermophysical and microwave crack-healing properties of asphalt mixtures. With this purpose, asphalt mixtures with two different types of metallic waste, steel wool fibres and steel shavings, added in four different contents, were tested. Electrical and thermophysical properties of asphalt mixture specimens with, and without, metallic waste were measured. The spatial distribution of the metallic waste inside the asphalt mixture samples was evaluated by using X-ray computed tomography. In addition, crack-healing properties of asphalt samples using microwave radiation heating were assessed at two different healing times, 30 s and 40 s. To quantify the efficiency of the healing process, five healing cycles were carried out for each asphalt sample. The main results showed that asphalt mixtures with shavings presented lower air void contents than mixtures with fibres. Moreover, fibres produced an increase in the electrical conductivity of the mixtures because long fibres in the mixtures form electrically conductive channels. In contrast, shavings did not have significant effect on the electrical properties of the mixtures. Likewise, it was proven that metallic waste reduced the thermal conductivity and the specific heat capacity of asphalt mixtures. Conversely, shavings decreased the thermal diffusivity of asphalt mixtures regardless of their content. Overall, it was found that the healing level reached by the asphalt mixtures tested by microwave radiation depends on the healing time and the type and content of metallic waste used. CT-scans results proved that the spatial distribution of metallic waste inside the asphalt mixture samples was not uniform and played an important role in the asphalt self-healing properties using microwave radiation heating.","Crack-healing asphalt; Electrical resistivity; Microwave heating; Thermal conductivity; Waste distribution","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-02-18","","","Materials and Environment","","",""
"uuid:0ce45ddb-4932-4808-aa92-bd13deb85fa9","http://resolver.tudelft.nl/uuid:0ce45ddb-4932-4808-aa92-bd13deb85fa9","Algebraic Multiscale Framework for Fractured Reservoir Simulation","Tene, M. (TU Delft Reservoir Engineering)","Jansen, J.D. (promotor); Hajibeygi, H. (copromotor); Delft University of Technology (degree granting institution)","2018","Despite welcome increases in the adoption of renewable energy sources, oil and natural gas are likely to remain the main ingredient in the global energy diet for the decades to come. Therefore, the efficient exploitation of existing suburface reserves is essential for the well-being of society. This has stimulated recent developments in computer models able to provide critical insight into the evolution of the flow of water, gas and hydrocarbons through rock pores. Any such endeavour, however, has to tackle a number of challenges, including the considerable size of the domain, the highly heterogeneous spatial distribution of geological properties, as well as the intrinsic uncertainty and limitations associated with field data acquisition. In addition, the naturally-formed or artificially induced networks of fractures, present in the rock, require special treatment, due to their complex geometry and crucial impact on fluid flow patterns.
From a numerical point of view, a reservoir simulator’s operation entails the solution of a series linear systems, as dictated by the spatial and temporal discretization of the governing equations. The difficulty lies in the properties of these systems, which are large, ill-conditioned and often have an irregular sparsity pattern. Therefore, a brute-force approach, where the solutions are directly computed at the original fine-scale resolution, is often an impractically expensive venture, despite recent advances in parallel computing hardware. On the other hand, switching to a coarser resolution to obtain faster results, runs the risk of omitting important features of the flow, which is especially true in the case of fractured porous media.
This thesis describes an algebraic multiscale approach for fractured reservoir simulation. Its purpose is to offer a middle-ground, by delivering results at the
original resolution, while solving the equations on the coarse-scale. This is made possible by the so-called basis functions – a set of locally-supported cross-scale interpolators, conforming to the heterogeneities in the domain. The novelty of the work lies in the extension of these methods to capture the effect of fractures. Importantly, this is done in fully algebraic fashion, i.e. without making any assumptions regarding geometry or conductivity properties.
In order to elicit the generality of the proposed approach, a series of sensitivity studies are conducted on a proof-of-concept implementation. The results, which include both CPU times and convergence behaviour, are discussed and compared to those obtained using an industrial-grade AMG package. They serve as benchmarks, recommending the inclusion of multiscale methods in next-generation commercial reservoir simulators.","algebraic multiscale methods; naturally fractured porous media; conductivity contrasts; compressible flow; multiphase transport","en","doctoral thesis","","978-94-6186-956-2","","","","","","","","","Reservoir Engineering","","",""
"uuid:da689def-97eb-4199-88a9-0637d820e47b","http://resolver.tudelft.nl/uuid:da689def-97eb-4199-88a9-0637d820e47b","Single–molecule conductance measurements: Correlations between chemical design and electronic properties","Olavarria Contreras, I.J. (TU Delft QN/van der Zant Lab)","van der Zant, H.S.J. (promotor); Dulic, D. (promotor); Delft University of Technology (degree granting institution)","2018","This thesis is about measurements of the electrical properties of different families of molecules. The research was focused on fundamental questions of charge transport in organic molecules. With this aim, experiments were performed to shed light on the underlying transport mechanisms. For example, an important ingredient of the work concerned the understanding of quantum interference effects in transport. On the other hand, several bio-inspired molecules were tested as electrical components revealing, for example, that with a certain chemical design a single-curcuminoid molecule act as a switch.","single-molecule electronics; conductance measurements; mechanically controlled break junction; quantum transport; curcuminoids; salen; carbon-gold bond","en","doctoral thesis","","9789085933526","","","","","","2019-07-02","","","QN/van der Zant Lab","","",""
"uuid:4f0141e7-9b97-4ed4-86be-9b885b420423","http://resolver.tudelft.nl/uuid:4f0141e7-9b97-4ed4-86be-9b885b420423","Mimicking the nuclear pore complex using nanopores","Ananth, A.N. (TU Delft BN/Cees Dekker Lab)","Dekker, C. (promotor); Delft University of Technology (degree granting institution)","2018","Nuclear pore complexes acts as a gatekeeper for molecular transport between the nucleus and the cytoplasm in eukaryotic cells. The central NPC channel is filled with intrinsically disordered FG domains (phenylalanine (F), glycine (G)) that are responsible for the fascinating selectivity of NPCs, for which the underlying mechanism is still under considerable debate. In this thesis, a minimalistic mimic of (NPCs) was constructed using solid-state nanopore and DNA origami to study the spatial arrangement and transport process.","Single-molecule; solid-state nanopore; nuclear pore complex; proteins; ionic conductance; DNA origami; surface chemistry","en","doctoral thesis","","9789085933427","","","","","","","","","BN/Cees Dekker Lab","","",""
"uuid:3b4522a3-2e19-4151-8f96-2c2db75545fb","http://resolver.tudelft.nl/uuid:3b4522a3-2e19-4151-8f96-2c2db75545fb","On Effective Graphene Based Computing","Cucu Laurenciu, N. (TU Delft Computer Engineering); Cotofana, S.D. (TU Delft Computer Engineering)","Dinescu, M.A. (editor); Dobrescu, D. (editor); Muller, A. (editor); Cristea, D. (editor); Dragoman, M. (editor); Muller, R. (editor); Ciurea, M.L. (editor); Neculoiu, D. (editor); Brezeanu, Gh. (editor)","2018","With CMOS feature size heading towards atomic dimensions, unjustifiable static power, reliability, and economic implications are exacerbating, prompting for research on new materials, devices, and/or computation paradigms. Within this context, Graphene Nanoribbons (GNRs), owing to graphene's excellent electronic properties, may serve as basic blocks for carbon-based nanoelectronics. In this paper, we present the two main avenues, i.e., graphene FET- and GNR- based, undertaken towards graphene based computing. The first approach is conservative and focuses on the realization of graphene FET transistor based switches as MOSFET replacements to maintain the state of the art logic Boolean algebra paradigm design methodology. The second one follows a different line of thinking and seeks GNR-based structures able to provide more complex behaviours by making better use of graphene's conduction properties. We first discuss Graphene Nanoribbon (GNR) based field Effect Transistors (GNRFETs) and Tunnelling GNR based Transistors (GNRTFETs) and their utilization as underlying elements for Boolean gate implementations. Subsequently, we present GNR-based structures that can directly compute Boolean functions, e.g., NAND, XOR, by means of one GNR only and a way to complementary arrange them in energy effective gates. To get inside into the potential of the two avenues we consider an inverter as discussion vehicle and evaluate the designs in terms of area and energy consumption. The GNR-based structure outperforms its counterparts by 15× up to 104× and 230× smaller delay and 6 to 7 and 4 orders of magnitude smaller power than the GNRFET-and GNRTFET- based designs, respectively. Moreover, when compared with CMOS 7 nm Boolean gates GNR-based desgns exhibit up to 6× smaller delay, and up to 2 orders of magnitude smaller active area, and total power consumption. Our analysis confirms that the alternative GNR-based design paradigm, which transcends the traditional switch based approach and takes better advantage of graphene intrinsicnproperties, is better suited for future carbon based nanoelectronics.","Boolean Gates; Carbon-N anoelectronics; Conduction Maps; Energy Efficiency; Graphene Nanoribbons; Graphene-based Boolean Gates","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","Accepted author manuscript","","","","","Computer Engineering","","",""
"uuid:ed259d10-9cf2-4617-baaa-c99330752025","http://resolver.tudelft.nl/uuid:ed259d10-9cf2-4617-baaa-c99330752025","Long-distance electron transport in individual, living cable bacteria","Bjerg, Jesper T. (Aarhus University); Boschker, H.T.S. (TU Delft BT/Environmental Biotechnology; Universiteit Antwerpen); Larsen, Steffen (Aarhus University); Berry, David (University of Vienna); Schmid, Markus (University of Vienna); Millo, Diego (Vrije Universiteit Amsterdam); Tataru, Paula (Aarhus University); Meysman, F.J.R. (TU Delft BT/Environmental Biotechnology; Universiteit Antwerpen); Wagner, Michael (University of Vienna); Nielsen, Lars Peter (Aarhus University); Schramm, Andreas (Aarhus University)","","2018","Electron transport within living cells is essential for energy conservation in all respiring and photosynthetic organisms. While a few bacteria transport electrons over micrometer distances to their surroundings, filaments of cable bacteria are hypothesized to conduct electric currents over centimeter distances. We used resonance Raman microscopy to analyze cytochrome redox states in living cable bacteria. Cable-bacteria filaments were placed in microscope chambers with sulfide as electron source and oxygen as electron sink at opposite ends. Along individual filaments a gradient in cytochrome redox potential was detected, which immediately broke down upon removal of oxygen or laser cutting of the filaments. Without access to oxygen, a rapid shift toward more reduced cytochromes was observed, as electrons were no longer drained from the filament but accumulated in the cellular cytochromes. These results provide direct evidence for long-distance electron transport in living multicellular bacteria.","Cable bacteria; Conduction; Cytochrome c; Electromicrobiology; Raman spectroscopy","en","journal article","","","","","","","","2018-11-29","","","BT/Environmental Biotechnology","","",""
"uuid:25e2fc31-5258-4a19-8d6b-c35490b55c92","http://resolver.tudelft.nl/uuid:25e2fc31-5258-4a19-8d6b-c35490b55c92","Thermal Modelling and Experimental Validation for Research on Medium Voltage DC Cables","Shekhar, A. (TU Delft DC systems, Energy conversion & Storage; The University of Texas at Austin); Feng, X. (The University of Texas at Austin); Hebner, R. (The University of Texas at Austin); Gattozzi, A. (The University of Texas at Austin); Strank, S. (The University of Texas at Austin); Mor, A. R. (TU Delft DC systems, Energy conversion & Storage; The University of Texas at Austin); Ramirez Elizondo, L.M. (TU Delft DC systems, Energy conversion & Storage; The University of Texas at Austin); Bauer, P. (TU Delft DC systems, Energy conversion & Storage; The University of Texas at Austin)","","2018","The thermal behavior of medium voltage dc cables can find useful applications for efficient and capacity enhanced operation in cities as well as compact power transmission on all electric ships. Concepts such as dynamic current and voltage rating, difference in thermal proximity in ac and dc operation, pulsed load application and thermal degradation with enhanced dc voltage; all are interlaced with the crucial temperature profile of insulated conductors. This paper develops a theoretical thermal model to highlight the possibility of dynamic current rating with pulsed loads. Further, a novel idea of imposing a thermal profile on cables for dc partial discharge testing is discussed. For this purpose a heat transfer model for a segmented cable is developed and experimentally validated.","Power cables; Conductors; Cable shielding; Thermal conductivity; Power cable insulation","en","conference paper","IEEE","","","","","","","","","","DC systems, Energy conversion & Storage","","",""
"uuid:ad82cdcb-40d2-42e7-805e-ca99e36a2b56","http://resolver.tudelft.nl/uuid:ad82cdcb-40d2-42e7-805e-ca99e36a2b56","Dissipation Losses in Artificial Dielectric Layers","Cavallo, D. (TU Delft Tera-Hertz Sensing)","","2018","Closed-form expressions to describe artificial dielectric layers (ADLs) with finite conductivity are presented. The propagation of a generic plane wave within the artificial material is described by means of transmission line models, where each layer is represented as an equivalent shunt impedance. The given analytical formulas for the shunt impedance are derived assuming finite conductivity of the metal, thus also an accurate estimation of the losses within the artificial dielectric is obtained from the equivalent circuit. The expressions account for the reactive coupling between the layers due to higher order Floquet modes, thus remain valid even for extremely small electrical distance between layers.","Artificial dielectric layers; closed-form solutions; Conductivity; Dielectrics; equivalent circuit; Impedance; Magnetic domains; Magnetic tunneling; Metals; Surface impedance","en","journal article","","","","","","Accepted Author Manuscript","","","","","Tera-Hertz Sensing","","",""
"uuid:f3d86aa0-18b9-4c9c-b1ba-7765f51a5965","http://resolver.tudelft.nl/uuid:f3d86aa0-18b9-4c9c-b1ba-7765f51a5965","Heat source layout optimization for two-dimensional heat conduction using iterative reweighted L1-norm convex minimization","Aslan, Y. (TU Delft Microwave Sensing, Signals & Systems); Puskely, J. (TU Delft Microwave Sensing, Signals & Systems); Yarovoy, Alexander (TU Delft Microwave Sensing, Signals & Systems)","","2018","Optimization of heat source distribution in two dimensional heat conduction for electronic cooling problem is considered. Convex optimization is applied to this problem for the first time by reformulating the objective function and the non-convex constraints. Mathematical analysis is performed to describe the heat source equation and the combinatorial optimization problem. A sparsity based convex optimization technique is used to solve the problem approximately. The performance of the algorithm is tested by several cases with various boundary conditions and the results are compared with a uniformly distributed layout. These results indicate that through proper selection of the number of grid cells for placing the heat sources and a minimum inter-source spacing, the maximum temperature and temperature non-uniformity in the domain can be significantly reduced. To further assess the capabilities of the method, comparisons to the results available in the literature are also performed. Compared to the existing heat source layout optimization methods, the proposed algorithm can be implemented more easily using available convex programming tools and reduces the number of input control parameters and thus computation time and resources while achieving a similar or better cooling performance.","heat source layout; heat conduction optimization; compressed sensing; convex optimization","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","","","","Microwave Sensing, Signals & Systems","","",""
"uuid:b4be6930-cab5-41f0-880f-3c19e9848c5f","http://resolver.tudelft.nl/uuid:b4be6930-cab5-41f0-880f-3c19e9848c5f","Highly Photoconductive InP Quantum Dots Films and Solar Cells","Crisp, R.W. (TU Delft ChemE/Opto-electronic Materials); Kirkwood, N.R.M. (TU Delft ChemE/Opto-electronic Materials); Grimaldi, G. (TU Delft ChemE/Opto-electronic Materials); Kinge, Sachin (Toyota Motor Europe); Siebbeles, L.D.A. (TU Delft ChemE/Opto-electronic Materials); Houtepen, A.J. (TU Delft ChemE/Opto-electronic Materials)","","2018","InP and InZnP colloidal quantum dots (QDs) are promising materials for application in light-emitting devices, transistors, photovoltaics, and photocatalytic cells. In addition to possessing an appropriate bandgap, high absorption coefficient, and high bulk carrier mobilities, the intrinsic toxicity of InP and InZnP is much lower than for competing QDs that contain Cd or Pb–providing a potentially safer commercial product. However, compared to other colloidal QDs, InP QDs remain sparsely used in devices and their electronic transport properties are largely unexplored. Here, we use time-resolved microwave conductivity measurements to study charge transport in films of InP and InZnP colloidal quantum dots capped with a variety of short ligands. We find that transport in InP QDs is dominated by trapping effects, which are mitigated in InZnP QDs. We improve charge carrier mobilities with a range of ligand-exchange treatments and for the best treatments reach mobilities and lifetimes on par with those of PbS QD films used in efficient solar cells. To demonstrate the device-grade quality of these films, we construct solar cells based on InP & InZnP QDs with power conversion efficiencies of 0.65 and 1.2%, respectively. This represents a large step forward in developing Cd- and Pb-free next-generation optoelectronic devices.","indium phosphide; Ligand-exchange; nanocrystals; photovoltaic; quantum dots; time-resolved microwave conductivity","en","journal article","","","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:0c38a94a-0f60-4cdc-be36-3d7df74d9a7a","http://resolver.tudelft.nl/uuid:0c38a94a-0f60-4cdc-be36-3d7df74d9a7a","On the Effects of Variation of Thermal Conductivity in Buildings in the Italian Construction Sector","Berardi, Umberto (Toronto Metropolitan University); Tronchin, Lamberto (University of Bologna); Manfren, Massimiliano (University of Southampton); Nastasi, B. (TU Delft Building Physics)","","2018","Stationary and dynamic heat and mass transfer analyses of building components are an essential part of energy efficient design of new and retrofitted buildings. Generally, a single constant thermal conductivity value is assumed for each material layer in construction components. However, the variability of thermal conductivity may depend on many factors; temperature and moisture content are among the most relevant ones. A linear temperature dependence of thermal conductivity has been found experimentally for materials made of inorganic fibers such as rockwool or fiberglass, showing lower thermal conductivities at lower temperatures. On the contrary, a nonlinear temperature dependence has been found for foamed insulation materials like polyisocyanurate, with a significant deviation from linear behavior. For this reason, thermal conductivity assumptions used in thermal calculations of construction components and in whole-building performance simulations have to be critically questioned. This study aims to evaluate how temperature affects thermal conductivity of materials in building components such as exterior walls and flat roofs in different climate conditions. Therefore, experimental conductivities measured for four common insulation materials have been used as a basis to simulate the behavior of typical construction components in three different Italian climate conditions, corresponding to the cities of Turin, Rome, and Palermo.","insulation materials; thermal conductivity; building energy consumption; temperature dependence; high-performance buildings","en","journal article","","","","","","","","","","","Building Physics","","",""
"uuid:aa85ded7-4fe1-4461-b81e-bb145d7f46a7","http://resolver.tudelft.nl/uuid:aa85ded7-4fe1-4461-b81e-bb145d7f46a7","Light control of the nanoscale phase separation in heteroepitaxial nickelates","Mattoni, G. (TU Delft QN/Caviglia Lab); Manca, N. (TU Delft QN/Caviglia Lab); Hadjimichael, M. (University College London (UCL)); Zubko, P. (University College London (UCL)); van der Torren, J.H. (Universiteit Leiden); Yin, C. (Universiteit Leiden); Catalano, S. (University of Geneva); Gibert, M. (University of Geneva); Maccherozzi, F. (Diamond Light Source); Liu, Y. (Diamond Light Source); Dhesi, S.S. (Diamond Light Source); Caviglia, A. (TU Delft QN/Caviglia Lab)","","2018","Strongly correlated materials show unique solid-state phase transitions with rich nanoscale phenomenology that can be controlled by external stimuli. Particularly interesting is the case of light–matter interaction in the proximity of the metal–insulator transition of heteroepitaxial nickelates. In this work, we use near-infrared laser light in the high-intensity excitation regime to manipulate the nanoscale phase separation in NdNiO3. By tuning the laser intensity, we can reproducibly set the coverage of insulating nanodomains, which we image by photoemission electron microscopy, thus semipermanently configuring the material state. With the aid of transport measurements and finite element simulations, we identify two different timescales of thermal dynamics in the light–matter interaction: a steady-state and a fast transient local heating. These results open interesting perspectives for locally manipulating and reconfiguring electronic order at the nanoscale by optical means.","Conductivity; Critical phenomena; First order phase transitions; Metal-insulator transition; Microphase separation; Nucleation; ConductivityCritical phenomenaFirst order phase transitionsMetal-insulator transitionMicrophase separation; Heterostructures; Single crystal materials; Strongly correlated systems; terminal techniques; High-resolution electron microscopy; Photoexcitation; X-ray absorption spectroscopy; X-ray photoemission electron microscopy","en","journal article","","","","","","","","","","","QN/Caviglia Lab","","",""
"uuid:f59daf61-be02-45b2-8261-bcb1128fcd8b","http://resolver.tudelft.nl/uuid:f59daf61-be02-45b2-8261-bcb1128fcd8b","Blending electronics with the human body: A pathway toward a cybernetic future","Mehrali, Mehdi (Technical University of Denmark); Bagherifard, Sara (Politecnico di Milano); Akbari, Mohsen (University of Victoria); Thakur, Ashish (Technical University of Denmark); Mirani, Bahram (University of Victoria); Mehrali, M. (TU Delft Energy Technology); Hasany, Masoud (Technical University of Denmark); Orive, Gorka (University of the Basque Country); Das, Paramita (Nanyang Technological University); Emneus, Jenny (Technical University of Denmark); Andresen, Thomas L. (Technical University of Denmark); Dolatshahi-Pirouz, Alireza (Technical University of Denmark)","","2018","At the crossroads of chemistry, electronics, mechanical engineering, polymer science, biology, tissue engineering, computer science, and materials science, electrical devices are currently being engineered that blend directly within organs and tissues. These sophisticated devices are mediators, recorders, and stimulators of electricity with the capacity to monitor important electrophysiological events, replace disabled body parts, or even stimulate tissues to overcome their current limitations. They are therefore capable of leading humanity forward into the age of cyborgs, a time in which human biology can be hacked at will to yield beings with abilities beyond their natural capabilities. The resulting advances have been made possible by the emergence of conformal and soft electronic materials that can readily integrate with the curvilinear, dynamic, delicate, and flexible human body. This article discusses the recent rapid pace of development in the field of cybernetics with special emphasis on the important role that flexible and electrically active materials have played therein.","conductive polymers; cyborganics; flexible bioelectronics; nanomaterials; wearable healthcare monitors","en","journal article","","","","","","","","","","","Energy Technology","","",""
"uuid:69ac7b36-c2c3-4813-835c-2630f796b38d","http://resolver.tudelft.nl/uuid:69ac7b36-c2c3-4813-835c-2630f796b38d","Correlated, Dual-Beam Optical Gating in Coupled Organic–Inorganic Nanostructures","Wurst, Kai M. (Eberhard Karls Universität Tübingen); Bender, Markus (University of Heidelberg); Lauth, J.D. (University of Oldenburg); Maiti, Sonam (Eberhard Karls Universität Tübingen); Chassé, Thomas (Eberhard Karls Universität Tübingen); Meixner, Alfred (Eberhard Karls Universität Tübingen); Siebbeles, L.D.A. (TU Delft ChemE/Chemical Engineering; TU Delft ChemE/Opto-electronic Materials); Bunz, Uwe H.F. (University of Heidelberg); Braun, Kai (Eberhard Karls Universität Tübingen); Scheele, Marcus (Eberhard Karls Universität Tübingen)","","2018","An optical switch with two distinct resonances is formed by combining PbS nanocrystals and the conductive polymer poly[sodium 2-(2-ethynyl-4-methoxyphenoxy)acetate] (PAE) into a hybrid thin film. Infrared excitation of the nanocrystals invokes charge transfer and consecutive polaron formation in the PAE, which activates the switch for excited-state absorption at visible frequencies. The optical modulation of the photocurrent response of the switch exhibits highly wavelength-selective ON/OFF ratios. Transient absorption spectroscopy shows that the polaron formation is correlated with the excited state of the nanocrystals, opening up new perspectives for photonic data processing. Such correlated activated absorption can be exploited to enhance the sensitivity for one optical signal by a second light source of different frequency as part of an optical amplifier or a device with AND logic.","conductive polymers; coupled organic–inorganic nanostructures; photoswitches; polarons","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-01-01","","ChemE/Chemical Engineering","ChemE/Opto-electronic Materials","","",""
"uuid:b641d368-242e-45fe-8c31-e7d25f07a179","http://resolver.tudelft.nl/uuid:b641d368-242e-45fe-8c31-e7d25f07a179","Electrically conducting fibres for e-textiles: An open playground for conjugated polymers and carbon nanomaterials","Lund, Anja (Chalmers University of Technology); van der Velden, N.M. (TU Delft Design for Sustainability); Persson, Nils-Krister (University of Borås); Hamedi, Mahiar M. (KTH Royal Institute of Technology); Müller, Christian (Chalmers University of Technology)","","2018","Conducting fibres and yarns promise to become an essential part of the next generation of wearable electronics that seamlessly integrate electronic function into one of the most versatile and most widely used form of materials: textiles. This review explores the many types of conducting fibres and yarns that can be realised with conjugated polymers and carbon materials, including carbon black, carbon nanotubes and graphene. We discuss how the interplay of materials properties and the chosen processing technique lead to fibres with a wide range of electrical and mechanical properties. Depending on the choice of conjugated polymer, carbon nanotube, graphene, polymer blend, or nanocomposite the electrical conductivity can vary from less than 10−3 to more than 103 S cm−1, accompanied by an increase in Young's modulus from 10 s of MPa to 100 s of GPa. Further, we discuss how conducting fibres can be integrated into electronic textiles (e-textiles) through e.g. weaving and knitting. Then, we provide an overview of some of the envisaged functionalities, such as sensing, data processing and storage, as well as energy harvesting e.g. by using the piezoelectric, thermoelectric, triboelectric or photovoltaic effect. Finally, we critically discuss sustainability aspects such as the supply of materials, their toxicity, the embodied energy of fibre and textile production and recyclability, which currently are not adequately considered but must be taken into account to ready carbon based conducting fibres for truly practical e-textile applications.","Carbon nanotubes; Conducting fibres; Conjugated polymers; E-textiles; Graphene; Nanocomposites","en","review","","","","","","Accepted author manuscript","","2020-05-07","","","Design for Sustainability","","",""
"uuid:4aeb9971-b567-4ba8-a9da-3776e0f69433","http://resolver.tudelft.nl/uuid:4aeb9971-b567-4ba8-a9da-3776e0f69433","Facile Synthesis toward the Optimal Structure-Conductivity Characteristics of the Argyrodite Li6PS5Cl Solid-State Electrolyte","Yu, C. (TU Delft RST/Fundamental Aspects of Materials and Energy); Ganapathy, S. (TU Delft RST/Storage of Electrochemical Energy); Hageman, J.G. (TU Delft Applied Sciences); van Eijck, L. (TU Delft RST/Neutron and Positron Methods in Materials); Van Eck, Ernst R.H. (Radboud Universiteit Nijmegen); Zhang, Long (Yanshan University); Schwietert, T.K. (TU Delft Applied Sciences); Basak, S. (TU Delft RST/Storage of Electrochemical Energy); Kelder, E.M. (TU Delft RST/Storage of Electrochemical Energy); Wagemaker, M. (TU Delft RST/Storage of Electrochemical Energy)","","2018","The high Li-ion conductivity of the argyrodite Li6PS5Cl makes it a promising solid electrolyte candidate for all-solid-state Li-ion batteries. For future application, it is essential to identify facile synthesis procedures and to relate the synthesis conditions to the solid electrolyte material performance. Here, a simple optimized synthesis route is investigated that avoids intensive ball milling by direct annealing of the mixed precursors at 550 °C for 10 h, resulting in argyrodite Li6PS5Cl with a high Li-ion conductivity of up to 4.96 × 10-3 S cm-1 at 26.2 °C. Both the temperature-dependent alternating current impedance conductivities and solid-state NMR spin-lattice relaxation rates demonstrate that the Li6PS5Cl prepared under these conditions results in a higher conductivity and Li-ion mobility compared to materials prepared by the traditional mechanical milling route. The origin of the improved conductivity appears to be a combination of the optimal local Cl structure and its homogeneous distribution in the material. All-solid-state cells consisting of an 80Li2S-20LiI cathode, the optimized Li6PS5Cl electrolyte, and an In anode showed a relatively good electrochemical performance with an initial discharge capacity of 662.6 mAh g-1 when a current density of 0.13 mA cm-2 was used, corresponding to a C-rate of approximately C/20. On direct comparison with a solid-state battery using a solid electrolyte prepared by the mechanical milling route, the battery made with the new material exhibits a higher initial discharge capacity and Coulombic efficiency at a higher current density with better cycling stability. Nevertheless, the cycling stability is limited by the electrolyte stability, which is a major concern for these types of solid-state batteries.","argyrodite; conductivity; solid-state batteries; structure; sulfide solid electrolyte","en","journal article","","","","","","","","","Applied Sciences","","RST/Fundamental Aspects of Materials and Energy","","",""
"uuid:025c6de2-9cb1-473d-b9c4-ff7574cb766a","http://resolver.tudelft.nl/uuid:025c6de2-9cb1-473d-b9c4-ff7574cb766a","Boron doping induced thermal conductivity enhancement of water-based 3C-Si(B)C nanofluids","Li, Bin (University of Science and Technology Beijing); Jiang, Peng (University of Science and Technology Beijing); Zhai, Famin (University of Science and Technology Beijing); Chen, Junhong (University of Science and Technology Beijing); Bei, G. (TU Delft (OLD) MSE-1; University of Science and Technology Beijing); Hou, Xinmei (University of Science and Technology Beijing); Chou, Kuo Chih (University of Science and Technology Beijing)","","2018","In this paper, the fabrication and thermal conductivity (TC) of water-based nanofluids using boron (B)-doped SiC as dispersions are reported. Doping B into the β-SiC phase leads to the shrinkage of the SiC lattice due to the substitution of Si atoms (0.134 nm radius) by smaller B atoms (0.095 nm radius). The presence of B in the SiC phase also promotes crystallization and grain growth of obtained particles. The tailored crystal structure and morphology of B-doped SiC nanoparticles are beneficial for the TC improvement of the nanofluids by using them as dispersions. Using B-doped SiC nanoparticles as dispersions for nanofluids, a remarkable improvement in stability was achieved in SiC-B6 nanofluid at pH 11 by means of the Zeta potential measurement. By dispersing B-doped SiC nanoparticles in water-based fluids, the TC of the as-prepared nanofluids containing only 0.3 vol.% SiC-B6 nanoparticles is remarkably raised to 39.3% at 30 °C compared to the base fluids, and is further enhanced with the increased temperature. The main reasons for the improvement in TC of SiC-B6 nanofluids are more stable dispersion and intensive charge ions vibration around the surface of nanoparticles as well as the enhanced TC of the SiC-B dispersions.","boron doping; SiC nanofluids; stability; thermal conductivity","en","journal article","","","","","","Accepted Author Manuscript","","2019-06-22","","","(OLD) MSE-1","","",""
"uuid:d78c827c-a98d-49f3-9171-b83eb288ae9c","http://resolver.tudelft.nl/uuid:d78c827c-a98d-49f3-9171-b83eb288ae9c","A Phase-Domain Readout Circuit for a CMOS-Compatible Hot-Wire CO₂ Sensor","Cai, Z. (TU Delft Electronic Instrumentation; NXP Semiconductors); van Veldhoven, Robert (NXP Semiconductors); Suy, Hilco (Ams AG); de Graaf, G. (TU Delft Electronic Instrumentation); Makinwa, K.A.A. (TU Delft Microelectronics); Pertijs, M.A.P. (TU Delft Electronic Instrumentation)","","2018","This paper presents a readout circuit for a carbon dioxide (COࠢ) sensor that measures the CO₂-dependent thermal time constant of a hot-wire transducer. The readout circuit periodically heats up the transducer and uses a phase-domain Δ Σ modulator to digitize the phase shift of the resulting temperature transients. A single resistive transducer is used both as a heater and as a temperature sensor, thus greatly simplifying its fabrication. To extract the transducer's resistance, and hence its temperature, in the presence of large heating currents, a pair of transducers is configured as a differentially driven bridge. The transducers and the readout circuit have been implemented in a standard 0.16μm CMOS technology, with an active area of 0.3 and 3.14 mm², respectively. The sensor consumes 6.8 mW from a 1.8-V supply, of which 6.3 mW is dissipated in the transducers. A resolution of 94-ppm CO₂ is achieved in a 1.8-s measurement time, which corresponds to an energy consumption of 12 mJ per measurement, >10x less than prior CO₂ sensors in CMOS technology.","Carbon dioxide (CO₂) sensor; CMOS compatible; delta-sigma modulator; phase-domain readout; Energy measurement; resistive sensor; thermal conductivity (TC)","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2022-03-30","","Microelectronics","Electronic Instrumentation","","",""
"uuid:4f3dad57-ac30-435d-9ca3-38f7eaa05633","http://resolver.tudelft.nl/uuid:4f3dad57-ac30-435d-9ca3-38f7eaa05633","Observation of Conductance Quantization in InSb Nanowire Networks","Fadaly, E.M.T. (TU Delft QRD/Kouwenhoven Lab; TU Delft QuTech Advanced Research Centre; Eindhoven University of Technology; Kavli institute of nanoscience Delft); Zhang, H. (TU Delft QRD/Kouwenhoven Lab; TU Delft QuTech Advanced Research Centre; Kavli institute of nanoscience Delft); Conesa Boj, S. (TU Delft QN/Conesa-Boj Lab; TU Delft QuTech Advanced Research Centre; Kavli institute of nanoscience Delft); Car, D. (TU Delft QRD/Kouwenhoven Lab; TU Delft QuTech Advanced Research Centre; Eindhoven University of Technology; Kavli institute of nanoscience Delft); Gül, Önder (TU Delft QRD/Kouwenhoven Lab; TU Delft QuTech Advanced Research Centre; Kavli institute of nanoscience Delft); Plissard, Sébastien R. (Eindhoven University of Technology); op het Veld, R.L.M. (TU Delft QRD/Kouwenhoven Lab; TU Delft QuTech Advanced Research Centre; Eindhoven University of Technology; Kavli institute of nanoscience Delft); Kölling, Sebastian (Eindhoven University of Technology); Kouwenhoven, Leo P. (TU Delft QRD/Kouwenhoven Lab; TU Delft QuTech Advanced Research Centre; Microsoft Quantum Lab Delft; Kavli institute of nanoscience Delft); Bakkers, E.P.A.M. (TU Delft QN/Bakkers Lab; TU Delft QuTech Advanced Research Centre; Eindhoven University of Technology; Kavli institute of nanoscience Delft)","","2017","Majorana zero modes (MZMs) are prime candidates for robust topological quantum bits, holding a great promise for quantum computing. Semiconducting nanowires with strong spin orbit coupling offer a promising platform to harness one-dimensional electron transport for Majorana physics. Demonstrating the topological nature of MZMs relies on braiding, accomplished by moving MZMs around each other in a certain sequence. Most of the proposed Majorana braiding circuits require nanowire networks with minimal disorder. Here, the electronic transport across a junction between two merged InSb nanowires is studied to investigate how disordered these nanowire networks are. Conductance quantization plateaus are observed in most of the contact pairs of the epitaxial InSb nanowire networks: the hallmark of ballistic transport behavior.","ballistic transport; conductance quantization; indium antimonide; networks; Semiconducting nanowires","en","journal article","","","","","","","","","","","QRD/Kouwenhoven Lab","","",""
"uuid:72824e9e-cb4e-4161-bd80-6a665b634739","http://resolver.tudelft.nl/uuid:72824e9e-cb4e-4161-bd80-6a665b634739","Hybrid Organic - Inorganic Polymer Electrolyte Membranes for Low to Medium Temperature Fuel Cells","Cordova Chavez, M.E. (TU Delft OLD ChemE/Organic Materials and Interfaces)","Picken, S.J. (promotor); Kelder, E.M. (copromotor); Delft University of Technology (degree granting institution)","2017","Crude oil, coal and gas are currently the main resources of energy in the world. The World Energy Outlook claimed in 2007 that the major source of energy (about 84%) would still be generated from fossil fuels in 2030. By these projections, the world's fossil fuel reserves will be consumed within a few decades, making it necessary to have a well stablished replacement for fossil fuels to fulfil our energy demands. Furthermore, the environmental impacts of fossil fuels are becoming clearer to scientists and governments. Among the population, environmental awareness is increasing as well, which leads to an increase in the demand for energy that does not harm the environment.
Fuel Cells are one of the most promising clean energy technologies, which are in clear consideration to replace fossil fuels in the future. They work as electrochemical energy conversion devices, similar to batteries, but do not require the recharging process, since they just depend on the presence of fuel to keep producing electricity. In most fuel cells, hydrogen is supplied to the anode and oxygen to the cathode, which results in production of water, heat and what is the most important, electricity. Unfortunately, several drawbacks with fuel cells have been identified. Probably the most important one is the very high cost, which is caused by use of the expensive electrolyte membrane and the catalyst...","Fuel Cells; Electrolyte; sPEEK; Hybrid; BDS; Inner phase; Conductivity; LiBPO4","en","doctoral thesis","","978 94 028 0728 8","","","","","","2017-12-31","","","OLD ChemE/Organic Materials and Interfaces","","",""
"uuid:c4e85518-327f-46cc-8776-bf79912a1349","http://resolver.tudelft.nl/uuid:c4e85518-327f-46cc-8776-bf79912a1349","Metal Halide Perovskite Polycrystalline Films Exhibiting Properties of Single Crystals","Brenes, Roberto (Massachusetts Institute of Technology); Guo, Dengyang (TU Delft ChemE/Opto-electronic Materials); Osherov, Anna (Massachusetts Institute of Technology); Noel, Nakita K. (University of Oxford); Eames, Christopher (University of Bath); Hutter, E.M. (TU Delft ChemE/Opto-electronic Materials); Pathak, Sandeep K. (Massachusetts Institute of Technology; University of Oxford); Niroui, Farnaz (Massachusetts Institute of Technology); Friend, Richard H. (University of Cambridge); Islam, M. Saiful (University of Bath); Snaith, Henry J. (University of Oxford); Bulović, Vladimir (Massachusetts Institute of Technology); Savenije, T.J. (TU Delft ChemE/Opto-electronic Materials); Stranks, Samuel D. (Massachusetts Institute of Technology; University of Cambridge)","","2017","Metal halide perovskites are generating enormous excitement for use in solar cells and light-emission applications, but devices still show substantial non-radiative losses. Here, we show that by combining light and atmospheric treatments, we can increase the internal luminescence quantum efficiencies of polycrystalline perovskite films from 1% to 89%, with carrier lifetimes of 32 μs and diffusion lengths of 77 μm, comparable with perovskite single crystals. Remarkably, the surface recombination velocity of holes in the treated films is 0.4 cm/s, approaching the values for fully passivated crystalline silicon, which has the lowest values for any semiconductor to date. The enhancements translate to solar cell power-conversion efficiencies of 19.2%, with a near-instant rise to stabilized power output, consistent with suppression of ion migration. We propose a mechanism in which light creates superoxide species from oxygen that remove shallow surface states. The work reveals an industrially scalable post-treatment capable of producing state-of-the-art semiconducting films. Metal halide perovskites are exciting materials for low-cost optoelectronic devices such as solar cells and LEDs. In order to reach the theoretical efficiency limits for both applications, any parasitic non-radiative charge-carrier recombination losses, such as those mediated by carrier trapping, must be eliminated. At present, perovskite materials still suffer from substantial non-radiative decay, particularly under solar illumination conditions, and are therefore yet to reach their full potential. Perovskite single crystals have very low trap concentrations but their controlled growth into devices does not lend themselves to the advantages offered by solution-processing thin films such as roll-to-roll depositions. Here, we demonstrate the use of light and atmospheric treatments on polycrystalline perovskite films, resulting in minimal non-radiative losses and properties approaching those of perovskite single crystals and even the best crystalline semiconductors reported to date. The authors demonstrate the use of light and atmospheric treatments on polycrystalline perovskite thin films, resulting in properties approaching those of the best crystalline semiconductors reported to date. The results translate to exceptional photovoltaic device performances with rapid rises to stabilized power output consistent with an inhibition of ionic migration.","light-emission; passivation; perovskite solar cells; photoluminescence; photovoltaics; semiconductors; time-resolved microwave conductivity","en","journal article","","","","","","","","","","","ChemE/Opto-electronic Materials","","",""
"uuid:098cb173-5ca4-4b74-8ec1-f62ccf3eb356","http://resolver.tudelft.nl/uuid:098cb173-5ca4-4b74-8ec1-f62ccf3eb356","Setup for EMI Shielding Effectiveness Tests of Electrically Conductive Polymer Composites at Frequencies up to 3.0 GHz","Vieira Valente, R.D. (TU Delft Novel Aerospace Materials; Promolding); De Ruijter, Chris (Promolding); Vlasveld, Daniel (Promolding); van der Zwaag, S. (TU Delft Novel Aerospace Materials); Groen, W.A. (TU Delft Novel Aerospace Materials)","","2017","Conductive polymer composites have been receiving increased interest both from the scientific community and industry with a special focus on electromagnetic interference (EMI) shielding applications. In this paper, we present the design, EM wave simulation, and validation through S-parameters measurements of an EMI shielding effectiveness (SE) tester based on the ASTM D4935 standard, to be used in the development of such materials. EM wave simulations and computer aided design were used in parallel to improve the SE test setup performance, which resulted in a unique low-loss coaxial-spherical-conical smooth transition design that ensured the best tradeoff between sample size and performance. The proposed SE tester has an insertion loss smaller than 1 dB, with good reproducibility and a setup-independent frequency response in the frequency range from a few kHz up to 3 GHz.","ASTM D4935; coaxial sample holder; conductive polymer composites; electromagnetic interference; EMI test method; S-parameters; shielding effectiveness","en","journal article","","","","","","","","","","","Novel Aerospace Materials","","",""
"uuid:4b1f83ad-df5c-4f7f-9dde-d3ea2a6b79ec","http://resolver.tudelft.nl/uuid:4b1f83ad-df5c-4f7f-9dde-d3ea2a6b79ec","Electrical characterization of nanoparticle and protein networks","Holovchenko, A. (TU Delft QN/van der Zant Lab)","van der Zant, H.S.J. (promotor); Delft University of Technology (degree granting institution)","2017","This thesis describes the research directed towards practical realization of an on-chip biosensing technology and that of understanding charge transport mechanisms in organic and biological nanoobjects. For this, silicon-based chips with metallic nanoelectrodes were fabricated using electron-beam lithography and metal evaporation. The final devices have source-drain separations of tens of nanometres, so that several up to one nanoobject can be trapped in between the electrodes, depending on its size. The electrical characterization is typically performed at room temperature. A current was induced in the sample by applying a voltage across the junction first before the deposition of nanoobject to characterize the bare junction as a reference, and subsequently after deposition. An increase of current after the deposition indicates that nanoobjects participate in the charge carrier flow through the device. For some nanoobjects it was possible to influence the current flow by inducing changes in the environment, for instance by varying the temperature (Chapter 4) or by changing the gas composition (Chapter 5 and Chapter 6). This thesis constitutes the results of two topics: two-dimensional (graphene) electrodes for contacting single nanoobjects (Chapter 3 and Chapter 4), and the electrical characterization of biological iron containing protein networks (Chapter 5 and Chapter 6).","charge transport; two-terminal measurements; protein conductance; biosensors; protein networks; nanoelectrodes","en","doctoral thesis","","978-90-8593-307-6","","","","","","","","","QN/van der Zant Lab","","",""
"uuid:a29f1d59-b4a5-4cba-8532-ef95611ef7e7","http://resolver.tudelft.nl/uuid:a29f1d59-b4a5-4cba-8532-ef95611ef7e7","Shape optimization and optimal control for transient heat conduction problems using an isogeometric approach","Wang, Z. (TU Delft Aerospace Structures & Computational Mechanics); Turteltaub, S.R. (TU Delft Aerospace Structures & Computational Mechanics); Abdalla, M.M. (TU Delft Aerospace Structures & Computational Mechanics)","","2017","This work is concerned with the development of a framework to solve shape optimization problems for transient heat conduction problems within the context of isogeometric analysis (IGA). A general objective functional is used to accommodate both shape optimization and passive control problems under transient conditions. An adjoint sensitivity analysis, which accounts for possible discontinuities in the objective functional, is performed analytically and subsequently discretized within the context of IGA. The gradient of the objective functional is used in a descent algorithm to solve optimization problems. Numerical examples are presented to validate and demonstrate the capacity to manage thermal fields under transient conditions.","Adjoint method; Isogeometric analysis; Passive optimal control; Shape optimization; Transient heat conduction","en","journal article","","","","","","","","2019-03-16","","","Aerospace Structures & Computational Mechanics","","",""
"uuid:a29ccc13-6e1c-4919-ba0a-9ccbd599d7ef","http://resolver.tudelft.nl/uuid:a29ccc13-6e1c-4919-ba0a-9ccbd599d7ef","Effect of Interfacial Polarization and Water Absorption on the Dielectric Properties of Epoxy-Nanocomposites","Marx, Philipp (Polymer Competence Center Leoben; Montanuniversität Leoben); Wanner, Andrea (Polymer Competence Center Leoben; Montanuniversität Leoben); Zhang, Zucong (Polymer Competence Center Leoben); Jin, H. (TU Delft DC systems, Energy conversion & Storage); Tsekmes, I.A. (TU Delft DC systems, Energy conversion & Storage; Montanuniversität Leoben); Smit, J.J. (TU Delft EEMS - General); Kern, Wolfgang (Polymer Competence Center Leoben; Montan University of Leoben); Wiesbrock, Frank (Polymer Competence Center Leoben)","","2017","Five types of nanofillers, namely, silica, surface-silylated silica, alumina, surface-silylated alumina, and boron nitride, were tested in this study. Nanocomposites composed of an epoxy/amine resin and one of the five types of nanoparticles were tested as dielectrics with a focus on (i) the surface functionalization of the nanoparticles and (ii) the water absorption by the materials. The dispersability of the nanoparticles in the resin correlated with the composition (OH content) of their surfaces. The interfacial polarization of the thoroughly dried samples was found to increase at lowered frequencies and increased temperatures. The β relaxation, unlike the interfacial polarization, was not significantly increased at elevated temperatures (below the glass-transition temperature). Upon the absorption of water under ambient conditions, the interfacial polarization increased significantly, and the insulating properties decreased or even deteriorated. This effect was most pronounced in the nanocomposite containing silica, and occurred as well in the nanocomposites containing silylated silica or non-functionalized alumina. The alternating current (AC) breakdown strength of all specimens was in the range of 30 to 35 kV·mm−1. In direct current (DC) breakdown tests, the epoxy resin exhibited the lowest strength of 110 kV·mm−1; the nanocomposite containing surface-silylated alumina had a strength of 170 kV·mm−1. In summary, water absorption had the most relevant impact on the dielectric properties of nanocomposites containing nanoparticles, the surfaces of which interacted with the water molecules. Nanocomposites containing silylated alumina particles or boron nitride showed the best dielectric properties in this study.","epoxy resins; nanoparticles; surface functionalization; silylating agent; water uptake; permittivity; loss factor; interfacial polarization; thermal conductivity","en","contribution to periodical","","","","","","Special Issue ""Polymer Nanocomposites""","","","","","DC systems, Energy conversion & Storage","","",""
"uuid:c66c9e13-2e77-413a-8891-707c41bfa94e","http://resolver.tudelft.nl/uuid:c66c9e13-2e77-413a-8891-707c41bfa94e","High throughput soft embossing process for micro-patterning of PEDOT thin films","Fanzio, P. (TU Delft Micro and Nano Engineering); Cagliani, A. (Technical University of Denmark; CAPRES A/S); Peterffy, K.G. (TU Delft Micro and Nano Engineering); Sasso, L. (TU Delft Micro and Nano Engineering)","","2017","The patterning of conductive polymers is a major challenge in the implementation of these materials in several research and industrial applications, spanning from photovoltaics to biosensors. Within this context, we have developed a reliable technique to pattern a thin layer of the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) by means of a low cost and high throughput soft embossing process. We were able to reproduce a functional conductive pattern with a minimum dimension of 1 μm and to fabricate electrically decoupled electrodes. Moreover, the conductivity of the PEDOT films has been characterized, finding that a post-processing treatment with Ethylene Glycol allows an increase in conductivity and a decrease in water solubility of the PEDOT film. Finally, cyclic voltammetry demonstrates that the post-treatment also ensures the electrochemical activity of the film. Our technology offers a facile solution for the patterning of organic conductors with resolution in the micro scale, and can be the basis for the realization and development of polymeric microdevices with electrical and electrochemical functionalities.","Conductivity; Ethylene glycol; Micro-patterning; PEDOT; Soft electrodes; Soft embossing","en","journal article","","","","","","Accepted Author Manuscript","","2019-01-14","","","Micro and Nano Engineering","","",""
"uuid:744e2f57-2976-4f3b-a7d3-891fbfb0153a","http://resolver.tudelft.nl/uuid:744e2f57-2976-4f3b-a7d3-891fbfb0153a","Company strategies for responsible research and innovation (RRI): A conceptual model","van de Poel, I.R. (TU Delft Values Technology and Innovation); Asveld, L. (TU Delft BT/Biotechnology and Society); Flipse, S.M. (TU Delft Science Education and Communication); Klaassen, Pim (Rijksinstituut voor Volksgezondheid en Milieu (RIVM); Vrije Universiteit Amsterdam); Scholten, V.E. (TU Delft Economics of Technology and Innovation); Yaghmaei, E. (TU Delft Ethics & Philosophy of Technology)","","2017","Responsible research and innovation (RRI) has become an important topic in the academic community and in policy circles, but it has not yet been systematically included in the innovation process of companies. We discuss how companies can integrate RRI into their corporate social responsibility (CSR) policies and business strategy. To this end, we developed a conceptual model that links a company's RRI strategy to its context, and that helps to translate the RRI strategy into activities that result in RRI outcomes. We also propose a process for developing company-specific RRI key performance indicators (KPIs) that can support companies to measure RRI outcomes.","Acceptance; Business strategy; Code of conduct; Corporate social responsibility (CSR); Ethics; Industry; Innovation; Key performance indicators (KPIs); Pilot; Responsible research and innovation (RRI)","en","journal article","","","","","","","","","","Values Technology and Innovation","BT/Biotechnology and Society","","",""
"uuid:e16cdc49-6e96-4828-a68d-f4c5266b9128","http://resolver.tudelft.nl/uuid:e16cdc49-6e96-4828-a68d-f4c5266b9128","Microstructure for Thermal Impedance Spectroscopy for Biofuel Composition Measurement","Jiang, Bo (Student TU Delft); Ghaderi, M. (TU Delft Electronic Instrumentation); Bossche, A. (TU Delft Electronic Instrumentation); Visser, Jaco H. (Ford Motor Company); Wolffenbuttel, R.F. (TU Delft Electronic Instrumentation)","","2017","Thermal impedance spectroscopy has been investigated as a non-destructive technique to determine the composition of ternary mixtures of biofuels. The principle of the thermal conductivity detector has been extended for measuring both the thermal conductivity and the thermal capacity of biofuel in the range between 1 to 100 Hz, using an AC-operated polysilicon heater for injecting a sinusoidal heat flux, and another polysilicon strip at a well-defined spacing or thermopile sensors for measuring the in-phase and quadrature components of the resulting AC temperature difference.","thermal impedance spectroscopy; ternary mixture; conductivity; thermopile sensors; thermal conductivity detector","en","conference paper","","","","","","","","","","","Electronic Instrumentation","","",""
"uuid:29b7ab5f-40ec-464b-a8f0-e24284a439f0","http://resolver.tudelft.nl/uuid:29b7ab5f-40ec-464b-a8f0-e24284a439f0","Electrical and mechanical properties of asphalt concrete containing conductive fibers and fillers","Wang, H. (TU Delft Engineering Structures); Yang, Jun (Southeast University); Liao, Hui (Southeast University); Chen, Xianhua (Southeast University)","","2016","Electrically conductive asphalt concrete has the potential to satisfy multifunctional applications. Designing such asphalt concrete needs to balance the electrical and mechanical performance of asphalt concrete. The objective of this study is to design electrically conductive asphalt concrete without compromising on the mechanical properties of asphalt concrete. In order to achieve this goal, various tests have been conducted to investigate the effects of electrically conductive additives (steel fiber and graphite) on the laboratory-measured electrical and mechanical properties of asphalt concrete. The results from this study indicate that the critical embedded steel fiber length is 9.6 mm to maximize the fiber's potential to bridge across the crack from single fiber tensile test. Both steel fiber and graphite can produce conductive asphalt concrete with sufficiently low resistivity, but steel fiber is much more effective than graphite to improve the conductivity of asphalt concrete. A combination of steel fiber and graphite can precisely control the resistivity of asphalt concrete over a wider range. Besides, asphalt concrete containing an optimized amount of steel fibers has a significant improvement in Marshall Stability, rutting resistance, indirect tensile strength, and low temperature cracking resistance compared to the plain concrete. The addition of graphite could increase the permanent deformation resistance with compromised stability and low temperature performance. Asphalt concrete containing steel fibers and graphite weakens the steel fiber reinforcing and toughening effect, but still has a significant improvement in mechanical performance compared to the plain concrete.","Asphalt concrete; Electrical conductivity; Fiber; Graphite; Mechanical properties","en","journal article","","","","","","","","2018-10-01","","Engineering Structures","","","",""
"uuid:0e711cdd-2f12-4aaf-98ef-01e1faaf3a4f","http://resolver.tudelft.nl/uuid:0e711cdd-2f12-4aaf-98ef-01e1faaf3a4f","A Ratiometric Readout Circuit for Thermal-Conductivity-Based Resistive CO₂ Sensors","Cai, Z. (TU Delft Electronic Instrumentation); van Veldhoven, Robert H.M. (NXP Semiconductors); Falepin, A. (NXP Semiconductors); Suy, H. (NXP Semiconductors); Sterckx, E. (NXP Semiconductors); Bitterlich, C. (BL Environmental Sensors); Makinwa, K.A.A. (TU Delft Microelectronics); Pertijs, M.A.P. (TU Delft Electronic Instrumentation)","","2016","This paper reports a readout circuit for a resistive CO2 sensor, which operates by measuring the CO2-dependent thermal conductivity of air. A suspended hot-wire transducer, which acts both as a resistive heater and temperature sensor, exhibits a CO2-dependent heat loss to the surrounding air, allowing CO2 concentration to be derived from its temperature rise and power dissipation. The circuit employs a dual-mode incremental delta-sigma ADC to digitize these parameters relative to those of an identical, but isolated, reference transducer. This ratiometric approach results in a measurement that does not require precision voltage or power references. The readout circuit uses dynamically-swapped transducer pairs to cancel their baseline-resistance, so as to relax the required dynamic range of the ADC. In addition, dynamic element matching (DEM) is used to bias the transducer pairs at an accurate current ratio, making the measurement insensitive to the precise value of the bias current. The readout circuit has been implemented in a standard 0.16 μm CMOS technology. With commercial resistive micro-heaters, a CO2 sensing resolution of about 200 ppm (1σ) was achieved in a measurement time of 30 s. Similar results were obtained with CMOS-compatible tungsten-wire transducers, paving the way for fully-integrated CO2 sensors for air-quality monitoring.","delta sigma modulator; CO2 sensor; gas sensor; thermal conductivity; thermal resistance; resistive sensor; RDC; ratiometric","en","journal article","","","","","","Accepted Author Manuscript","","","","Microelectronics","Electronic Instrumentation","","",""
"uuid:c8da6c33-fd21-4917-8e3a-84726bb0d28d","http://resolver.tudelft.nl/uuid:c8da6c33-fd21-4917-8e3a-84726bb0d28d","B1-based SAR reconstruction using contrast source inversion–electric properties tomography (CSI-EPT)","Balidemaj, E. (Amsterdam UMC); van den Berg, Cornelis A.T. (University Medical Center Utrecht); van Lier, Astrid L.H.M.W. (University Medical Center Utrecht); Nederveen, Aart J. (Amsterdam UMC); Stalpers, Lukas J.A. (Amsterdam UMC); Crezee, Hans (Amsterdam UMC); Remis, R.F. (TU Delft Signal Processing Systems)","","2016","Specific absorption rate (SAR) assessment is essential for safety purposes during MR acquisition. Online SAR assessment is not trivial and requires, in addition, knowledge of the electric tissue properties and the electric fields in the human anatomy. In this study, the potential of the recently developed CSI-EPT method to reconstruct SAR distributions is investigated. This method is based on integral representations for the electromagnetic field and attempts to reconstruct the tissue parameters and the electric field strength based on B+1B1+ field data only. Full three-dimensional FDTD simulations using a female pelvis model are used to validate two-dimensional CSI reconstruction results in the central transverse plane of a 3T body coil. Numerical experiments demonstrate that the reconstructed SAR distributions are in good agreement with the SAR distributions as determined via 3D FDTD simulations and show that these distributions can be computed very efficiently in the central transverse plane of a body coil with the two-dimensional approach of CSI-EPT.","B1 maps; Specific absorption rate (SAR); Contrast source inversion (CSI); Electric properties tomography (EPT); Conductivity","en","journal article","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:d886d683-c4dc-4e56-97ce-ae4964909175","http://resolver.tudelft.nl/uuid:d886d683-c4dc-4e56-97ce-ae4964909175","Spatial conductivity mapping of unprotected and capped black phosphorus using microwave microscopy","de Visser, P.J. (TU Delft QN/Klapwijk Lab; University of Geneva); Chua, Rebekah (National University of Singapore; Student TU Delft); Island, J.O. (TU Delft QN/van der Zant Lab); Finkel, M. (TU Delft QN/Klapwijk Lab; Moscow State Pedagogical University); Katan, A.J. (TU Delft QN/Afdelingsbureau); Thierschmann, R. (TU Delft QN/Klapwijk Lab); van der Zant, H.S.J. (TU Delft QN/van der Zant Lab); Klapwijk, T.M. (TU Delft QN/Klapwijk Lab; Moscow State Pedagogical University)","","2016","Thin layers of black phosphorus present an ideal combination of a 2Dmaterial with a tunable direct bandgap and high carrier mobility. However the material suffers from degradation in ambient conditions due to an oxidation reaction which involves water, oxygen and light. Wehave measured the spatial profile of the conductivity on flakes of black phosphorus as a function of time using scanning microwave impedance microscopy. Amicrowave excitation (3 GHz) allows to image a conducting sample even when covered with a dielectric layer. Weobserve that on bare black phosphorus, the conductivity changes drastically over the whole surface within a day. Wedemonstrate that the degradation process is slowed down considerably by covering the material with a 10 nmlayer of hafnium oxide. It is stable for more than a week, opening up a route towards stable black phosphorus devices in which the high dielectric constant of hafnium oxide can be exploited. Covering black phosphorus with a 15 nmboron nitride flake changes the degradation process qualitatively, it is dominated by the edges of the flake indicating a diffusive process and happens on the scale of days.","Black phosphorus; Boron nitride; Conductivity; Degradation; Hafnium oxide; Microwave impedance microscopy","en","journal article","","","","","","","","","","","QN/Klapwijk Lab","","",""
"uuid:11caef74-1ce4-450f-b5ab-a7d7537937a7","http://resolver.tudelft.nl/uuid:11caef74-1ce4-450f-b5ab-a7d7537937a7","Deposition of conductive TiN shells on SiO2 nanoparticles with a fluidized bed ALD reactor","Didden, A.; Hillebrand, P.; Wollgarten, M.; Dam, B.; Van de Krol, R.","","2016","Conductive TiN shells have been deposited on SiO2 nanoparticles (10–20 nm primary particle size) with fluidized bed atomic layer deposition using TDMAT and NH3 as precursors. Analysis of the powders confirms that shell growth saturates at approximately 0.4 nm/cycle at TDMAT doses of >1.2 mmol/g of powder. TEM and XPS analysis showed that all particles were coated with homogeneous shells containing titanium. Due to the large specific surface area of the nanoparticles, the TiN shells rapidly oxidize upon exposure to air. Electrical measurements show that the partially oxidized shells are conducting, with apparent resistivity of approximately ~11 k? cm. The resistivity of the powders is strongly influenced by the NH3 dose, with a smaller dose giving an order-of-magnitude higher resistivity.","fluidized bed; atomic layer deposition; coreshell particles; titanium nitride; conductive shells; microelectronic contacts","en","journal article","Springer","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:c07dbb22-09c1-432b-a48a-4b122568143e","http://resolver.tudelft.nl/uuid:c07dbb22-09c1-432b-a48a-4b122568143e","Analysis of the Mechanisms Determining the Thermal and Electrical Properties of Epoxy Nanocomposites for High Voltage Applications","Tsekmes, I.A.","Smit, J.J. (promotor)","2016","The addition of microsized fillers to polymers, in order to tailor their properties, has been extensively used in many industrial applications since the 1960s. The same approach applies to the field of electrical insulation. Epoxy resin is a widely used polymer in the electrical power sector, but it is usually loaded with microsized fillers, such as aluminum oxide and silicon dioxide, mainly to increase its thermal conductivity, improve its mechanical properties, and to decrease cost. Polymers with microsized fillers are called microcomposites. In the mid-1990s, a new type of polymeric composites for high voltage applications, the so-called nanocomposites, emerged. The main characteristic of these composites is the small filler size, which is smaller than 100 nm at least in one dimension. Since then, there has been a growing interest in the performance of polymeric nanocomposites for high voltage applications, including epoxy nanocomposites. The performance of nanocomposites is mainly related to the tremendous effective internal surface area of these materials because of the high surface-tovolume ratio of nanofillers. After 20 years of research, a significant amount of data has been generated which reflects the potential of nanodielectrics. It has been shown that nanofillers are capable of contributing to the improvement of both the thermal and electrical properties of polymers. However, the laboratory performance of nanocomposites is inconsistent and unpredictable. These are the main factors which inhibit the applicability of nanodielectrics. Important challenges in the field of epoxy nanocomposites should be overcome before nanodielectrics can be produced on an industrial level. The most important challenge is related to the dubious reproducibility of the nanocomposite performance which is closely related to sample homogeneity. Thus, the effectiveness of separating the nanoparticles from each other and the homogeneous incorporation of them into the polymer matrix are expected to affect the performance of nanocomposites. However, the extent to which the behavior of nanocomposites is influenced by sample homogeneity is not well defined. In this thesis, a number of epoxy nanocomposites and mesocomposites were synthesized aiming at the analysis of the parameters which influence their thermal and electrical properties. The analysis includes the thermal and electrical conductivity, dielectric response, and breakdown strength under both AC and DC electric fields. The experimental results demonstrate the important role of interfaces in the behavior of epoxy nanocomposites. Based on the experimental results, important parameters for determining the performance of nanocomposites are suggested to be the polymer re-organization and water uptake. The former is related to the influence of nanofillers on the polymer structure, i.e., the areas in the vicinity of nanofillers are assumed to exhibita different behavior from the rest of the polymer matrix. The uptake of water is related mainly to the hydrophilic nature of nanofillers and plays a significant role in the electrical performance of nanocomposites. Apart from the aforementioned mechanisms, the presence of structural imperfections should not be neglected as they affect both the thermal and electrical properties of epoxy nanocomposites. Additionally to the experimental part, models were developed for both the relative permittivity and thermal conductivity of nanocomposites. The models are based on the two aforementioned parameters; polymer re-organization in the vicinity of nanofillers and water uptake due to the hydrophilicity of nanofillers. The main characteristic of both models is the use of the same structure which strengthens the validity of the assumptions. The experimental results are in good agreement with the model results. Also, a large part of the thesis is devoted to the evaluation of the influence of sample homogeneity on the performance of nanocomposites. For this purpose, nanocomposites with different synthesis techniques were fabricated. The results suggest that the thermal conductivity, dielectric response, and breakdown strength (AC and DC) of epoxy nanocomposites are not significantly influenced by the nanoparticle distribution. This observation suggests that high levels of reproducibility can be achieved when the particles are similarly dispersed and differently distributed. Finally, hybrid composites which combine both microsized and nanosized fillers were fabricated, tested, and analyzed. This type of composites is more likely to be employed in industry as epoxy resin in its pure form is rarely used for high voltage applications. It is usually reinforced with high loadings of microparticles. Microcomposites reinforced only with a small amount of nanofillers, i.e., less than 1 % by volume, show a significant thermal and electrical improvement.","epoxy nanocomposites; electrical properties; thermal properties; thermal conductivity; dielectric response; electrical conductivity; breakdown strength; epoxy microcomposites","en","doctoral thesis","","","","","","","","2016-01-31","Electrical Engineering, Mathematics and Computer Science","Electrical Sustainable Energy","","","",""
"uuid:86d1dfa4-f4b5-496c-b822-5f6fa6631b46","http://resolver.tudelft.nl/uuid:86d1dfa4-f4b5-496c-b822-5f6fa6631b46","Subnanometer-accuracy optical distance ruler based on fluorescence quenching by transparent conductors","Moerland, R.J.; Hoogenboom, J.P.","","2016","Available data: Complex refractive index of Indium Tin Oxide, http://dx.doi.org/10.4121/uuid:59febf27-a532-4ac9-8ec0-29d4195b2c8c Transparent conductive oxides (TCOs), such as the well-known indium-tin oxide, find widespread use in modern (nano)technological applications because of their unique combination of negligible optical absorption and good electric conductivity. We, however, show that despite the near-zero imaginary part of the refractive index that is responsible for the material’s transparency, TCOs drastically quench optical emitters when the emitter is within 10 nm from the TCO. Our results reveal that the pure near-field nature of this dissipation makes for an exquisite short-range optical ruler. Previous quenching-based optical rulers, based on interactions with plasmonic or graphene materials, have allowed measuring distances in the 20–100 nm range. Distances below 20 nm have, however, been hard to assess due to poor photon yields or weak absolute variations. We show that TCO-based rulers close this gap, allowing distance measurements with far-field optics in the 1–10 nm distance range with deep subnanometer sensitivity.","fluorescence microscopy; transparent conductive coatings; height measurements; OA-Fund TU Delft","en","journal article","Optical Society of America","","","","","","","","Applied Sciences","ImPhys/Imaging Physics","","","",""
"uuid:a05a8c81-5f02-4d12-9417-8fdba05e6983","http://resolver.tudelft.nl/uuid:a05a8c81-5f02-4d12-9417-8fdba05e6983","Isogeometric Shape Optimization for Quasi-static and Transient Problems","Wang, Z.P.","Bisagni, C. (promotor); Turteltaub, S.R. (promotor)","2016","The recently developed isogeometric analysis (IGA) was aimed, from the start, at integrating computer aided design (CAD) and analysis. This synthesis of geometry and analysis has naturally led to renewed interest in developing structural shape optimization. The advantages of using isogeometric analysis in shape optimization are embodied in its ability to preserve exact CAD geometrical descriptions and its enhanced potential to perform shape sensitivity analysis. Recent contributions in shape optimization within IGA have been limited to static or steady-state loading conditions. The purpose of this work was to extend the isogeometric shape optimization and identification to quasi-static and transient problems. The normalization approaches for the search directions in isogeometric shape optimization scheme and the mean value property of B-spline basis were also studied. Shape sensitivity analysis plays a critical role in structural shape optimization. In this dissertation, an adjoint sensitivity analysis was performed for arbitrary objective functionals defined for quasi-static and transient problems at the continuous level. The sensitivity for quasi-static and transient problems are essentially different with each other since the transient case has a time-derivative term involved in the time interval. The transport relations considering discontinuities were studied and used to derive the continuous adjoint shape sensitivity. Consideration of the discontinuities enabled the shape sensitivity analysis to be applicable for the problems where discontinuities were involved in the objective functional and state equations. Then within the context of IGA, the continuous sensitivity was discretized to obtain the discrete design sensitivity with respect to the design discretization, which was used to find the search directions used to update the shape numerically. A interesting phenomenon in shape optimization is that the use of the search direction directly predicted from the discrete shape gradient makes the optimization history strongly dependent on the discretization. This discretization dependency can affect convergence and may lead the optimization process into a sub-optimal solution. The source of this discretization dependency was traced to the lack of consistency with the local steepest descent search direction in the continuous formulation. This inconsistency was analyzed using the shape variation equations and subsequently illustrated with a volume minimization problem. It was found that the inconsistency originates from the NURBS discretization which induces a discrete quadratic norm to represent the continuous Euclidean norm. To fix this inconsistency, a standard normalization approach, which is used to find the steepest descent direction for quadratic norm problems, was proposed to obtain a consistent discretization independent search direction. The standard approach requires solving a linear system of equations. Using the diagonally lumped mapping matrix (DLMM) and the partition of unity property of NURBS, two simpler normalization approaches, which do not require solving a linear system of equations, were proposed. The discretization-independence of the proposed approaches was verified with a benchmark problem. The superiority of the proposed search direction and its suitability for numerical implementation is illustrated with examples of shape optimization for mechanical and thermal problems. In the derivation of the simplified normalization approaches, the mean value property of B-spline basis function is proposed and proved using mathematical induction method. Using the normalization approaches, two frameworks to solve shape optimization and identification problems for quasi-static and transient process, respectively, were developed and implemented numerically within the context of isogeometric analysis. Generalized objective functionals were used to accommodate both structural shape optimization and identification problems in arbitrary forms. The methodology and its numerical implementation were tested using benchmark problems or passive control approaches with priori known solutions. For the quasi-static case, application problems were considered where an external load was allowed to move along the surface of a structure. The shape of the structure was modified to control the time-dependent displacement of the point where the load was applied according to a pre-specified target. For the transient case, the shape optimization and identification was performed for a plunger design under a transient heating process and a thermal protection layer design for a ballistic re-entry vehicle.","isogeometric analysis; shape optimization; continuous adjoint method; quasi-static; transient heat conduction; normalization approaches; discretization/mesh-dependency","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:1c3a0a2b-6b92-4daa-98c7-513de8ed7623","http://resolver.tudelft.nl/uuid:1c3a0a2b-6b92-4daa-98c7-513de8ed7623","Introduction to an in-situ method for rapid measurement of the walls’ thermal resistance in existing buildings","Rasooli, A. (TU Delft OLD Housing Quality and Process Innovation); Itard, L.C.M. (TU Delft OLD Housing Quality and Process Innovation); Infante Ferreira, C.A. (TU Delft Engineering Thermodynamics)","Heiselberg, Per Kvols (editor)","2016","Large deviations observed between the actual and theoretical gas consumption in Dutch dwellings, cast a shadow of doubt on the accuracy of the energy labeling method. In this sense, the accuracy of the calculation methods as well as the inputs being fed, fall under the question. According to several studies, the significance of wall’s thermal resistance as one of the most sensitive inputs has become clear. From the lack of sufficient information regarding the exact construction of the existing walls, arises a necessity for in-situ measurements. However, such measurements are generally not being performed because the existing methods demand very long monitoring periods. In this research, a rapid transient in-situ thermal resistance measurement technique, Excitation Pulse Method (EPM), has been introduced, experimentally applied to a case study, and compared to the existing international standard method ISO 9869, showing a very good agreement. EPM is based on the theory of thermal response factors. It allows in-situ determination of the walls’ thermal resistance and the average volumetric heating capacity in a couple of hours. The method is therefore believed to aid in better and much quicker estimation of the","transient heat conduction; thermal resistance; response factors; energy labeling; in-situ measurement method","en","conference paper","Aalborg University","","","","","","","","","","OLD Housing Quality and Process Innovation","","",""
"uuid:152c6e44-129c-464a-9ccc-85939d760ddc","http://resolver.tudelft.nl/uuid:152c6e44-129c-464a-9ccc-85939d760ddc","Hydrodynamic behaviour of compacted granite sawdust from the dimension stone industry of Pontevedra (Spain): Experimental and Modelling","Falcon-Suarez, I. (University of Southampton); Juncosa-Rivera, R. (University of A Coruna); Vardon, P.J. (TU Delft Geo-engineering); Rammlmair, D. (Federal Institute for Geosciences and Natural Resources); Gunter, T. (Federal Institute for Geosciences and Natural Resources); Noell, U. (Federal Institute for Geosciences and Natural Resources); Delgado-Martın, J. (University of A Coruna)","","2016","Two large-scale column experiments have been performed to test the hydrodynamic behaviour of unsaturated, compacted granite sawdust—a material produced during the dressing of dimension stone in Pontevedra (Spain). One of the columns was equipped with psychrometers and capacitance probes while, in the other, a radial array of 80 electrodes made possible a time-dependent 3D electrical resistivity survey. All these devices allowed investigating and modelling the progressive saturation of the material. The study includes a straightforward methodology developed to calibrate the resistivity signals based on standard Proctor-compacted specimens. The progressive saturation of the granite sawdust reveals different stages: initially, an uneven advance of the saturation front (fingering) occurs; later on, this feature vanishes and is replaced by a more regular advance of the saturation front. Numerical analysis of the results shows that the yield capacity of the granite sawdust is*0.39 m3 m-3 and a saturated hydraulic conductivity *2 9 10-6 m s-1. The latter, which corresponds to the specific standard Proctor compaction, is not sufficient to support the use of granite sawdust for compacted-single-layer capping structures. Nonetheless, increased compaction efforts or improved design criteria (multilayer systems or capillary barriers) can keep bearing when considering granite sawdust for this purpose.","Sustainable waste management; Sanitary landfills; Unsaturated soil behaviour; Hydraulic conductivity; Yield capacity; Water fingering","en","journal article","","","","","","","","2017-02-28","","","Geo-engineering","","",""
"uuid:e5a47613-6f6c-48a6-a81e-16430c319586","http://resolver.tudelft.nl/uuid:e5a47613-6f6c-48a6-a81e-16430c319586","Electromagnetic Marchenko imaging in 1D for dissipative media","Zhang, L. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Staring, M. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","Sicking, Charles (editor); Ferguson, John (editor)","2016","We present a one-dimensional lossless scheme to compute an image of a dissipative medium from two single-sided reflection responses. One reflection response is measured at or above the top reflector of a dissipative medium and the other reflection response is computed as if measured at or above the top reflector of a medium with negative dissipation which we call the effectual medium. These two reflection responses together can be used to construct the approximate reflection data of the corresponding lossless medium by multiplying and taking the square root in time domain. The corresponding lossless medium has the same reflectors as the dissipative medium. Then the constructed reflection data can be used to compute the focusing wavefield which focuses at the chosen location in subsurface of the dissipative medium. From the focusing function and constructed reflection response the Green’s function for a virtual receiver can be obtained. Because the up- and downgoing parts of the Green’s function are retrieved separately, these are used to compute the image. We show with an example that the method works well for a sample in a synthesized waveguide that could be used for measurements in a laboratory.","electromagnetic; conductivity; internal multiples; permeability; GPR","en","conference paper","SEG","","","","","","","","","","Applied Geophysics and Petrophysics","","",""
"uuid:9102d990-179f-47bd-91a7-77c2db754d00","http://resolver.tudelft.nl/uuid:9102d990-179f-47bd-91a7-77c2db754d00","Combination of Advanced Optical Modelling with Electrical Simulation for Performance Evaluation of Practical 4-terminal Perovskite/c-Si Tandem Modules","Zhang, Dong (ECN-Solliance, High Tech Campus 21); Verhees, Wiljan (ECN-Solliance, High Tech Campus 21); Dörenkämper, Maarten (ECN-Solliance, High Tech Campus 21); Qiu, Weiming (IMEC-Solliance); Bakker, N.J. (ECN-Solliance, High Tech Campus 21); Gutjahr, Astrid (ECN-Solliance, High Tech Campus 21); Veenstra, Sjoerd (ECN-Solliance, High Tech Campus 21); Gehlhaar, Robert (IMEC-Solliance); Paetzold, Ulrich W. (IMEC-Solliance); Soppe, Wim (ECN-Solliance, High Tech Campus 21); Romijn, Ingrid (ECN-Solliance, High Tech Campus 21); Geerligs, LJ (ECN-Solliance, High Tech Campus 21); Aernouts, Tom (IMEC-Solliance); Weeber, A.W. (TU Delft Photovoltaic Materials and Devices; ECN-Solliance, High Tech Campus 21)","","2016","The perovskite solar cell is considered a promising candidate as the top cell for high-efficiency tandem devices with crystalline silicon (c-Si) bottom cells, contributing to the cost reduction of photovoltaic energy. In this contribution, a simulation method, involving optical and electrical modelling, is established to calculate the performance of 4-terminal (4T) perovskite/c-Si tandem devices on a mini-module level. Optical and electrical characterization of perovskite and c-Si solar cells are carried out to verify the simulation parameters. With our method, the influence of transparent conductive oxide (TCO) layer thickness of perovskite top cells on the performance of tandem mini-modules is investigated in case of both tin-doped indium oxide (ITO) and hydrogen-doped indium oxide (IO:H). The investigation shows that optimization of TCO layer thickness and replacement of conventional ITO with highly transparent IO:H can lead to an absolute efficiency increase of about 1%. Finally, a practical assessment of the efficiency potential for the 4T perovskite/c-Si tandem mini-module is carried out, indicating that with a relatively simple 4T tandem module structure the efficiency of a single-junction c-Si mini-module (19.3%) can be improved by absolute 4.5%.","4-terminal; hybrid tandem; perovskite solar cell; simulation; transparent conductive oxide","en","journal article","","","","","","","","","","","Photovoltaic Materials and Devices","","",""
"uuid:2c8e785e-438a-4597-890d-8d97af079eb6","http://resolver.tudelft.nl/uuid:2c8e785e-438a-4597-890d-8d97af079eb6","Compensating for electrode polarization in dielectric spectroscopy studies of colloidal suspensions: Theoretical assessment of existing methods","Chassagne, C. (TU Delft Environmental Fluid Mechanics); Dubois, Emmanuelle (Universite Pierre et Marie Curie (UPMC)); Jiménez, María L. (Universidad de Granada); Ploeg, J.C. (Universiteit Leiden); van Turnhout, J. (TU Delft ChemE/Algemeen)","","2016","Dielectric spectroscopy can be used to determine the dipole moment of colloidal particles from which important interfacial electrokinetic properties, for instance their zeta potential, can be deduced. Unfortunately, dielectric spectroscopy measurements are hampered by electrode polarization (EP). In this article, we review several procedures to compensate for this effect. First EP in electrolyte solutions is described: the complex conductivity is derived as function of frequency, for two cell geometries (planar and cylindrical) with blocking electrodes. The corresponding equivalent circuit for the electrolyte solution is given for each geometry. This equivalent circuit model is extended to suspensions. The complex conductivity of a suspension, in the presence of EP, is then calculated from the impedance. Different methods for compensating for EP are critically assessed, with the help of the theoretical findings. Their limit of validity is given in terms of characteristic frequencies. We can identify with one of these frequencies the frequency range within which data uncorrected for EP may be used to assess the dipole moment of colloidal particles. In order to extract this dipole moment from the measured data, two methods are reviewed: one is based on the use of existing models for the complex conductivity of suspensions, the other is the logarithmic derivative method. An extension to multiple relaxations of the logarithmic derivative method is proposed.","Colloidal suspension; Complex conductivity and permittivity; Electrode polarization; OA-Fund TU Delft","en","journal article","","","","","","","","","","","Environmental Fluid Mechanics","","",""
"uuid:6ac64ab7-73a8-4b91-90b1-b1632f960ad9","http://resolver.tudelft.nl/uuid:6ac64ab7-73a8-4b91-90b1-b1632f960ad9","Crosslinked Poly(2-oxazoline)s as “Green” Materials for Electronic Applications","Fimberger, M.; Tsekmes, I.A.; Kochetov, R.; Smit, J.J.; Wiesbrock, F.","","2015","Poly(2-nonyl-2-oxazoline)80-stat-poly(2-dec-9?-enyl-2-oxazoline)20 and poly(2-dec-9?-enyl-2-oxazoline)100 can be synthesized from the cationic ring-opening polymerization of monomers that can be derived from fatty acids from renewable resources. These (co)poly(2-oxazoline)s can be crosslinked with di- and trifunctional mercapto compounds using the UV-induced thiol-ene reaction. The complex permittivity of the corresponding networks increases with the temperature and decreases with the network density. In a frequency range from 10?2 to 106 Hz and at temperatures ranging from ?20 to 40 °C, the changes of the real part of the complex permittivity as well as the loss factor can be explained by interfacial polarization within the material. At a temperature of 20 °C and a frequency of 50 Hz, the permittivity of the crosslinked (co)poly(2-oxazoline)s covers a range from 4.29 to 4.97, and the loss factors are in the range from 0.030 to 0.093. The electrical conductivities of these polymer networks span a range from 5 × 10?12 to 8 × 10?9 S/m, classifying these materials as medium insulators. Notably, the values for the permittivity, loss factor and conductivity of these copoly(2-oxazoline)s are in the same range as for polyamides, and, hence, these copoly(2-oxazoline)-based networks may be referred to as “green” alternatives for polyamides as insulators in electronic applications.","poly(2-oxazoline)s; crosslinked polymers; thiol-ene click chemistry; permittivity; loss factor; interfacial polarization; electrical conductivity","en","journal article","MDPI","","","","","","","","Electrical Engineering, Mathematics and Computer Science","","","","",""
"uuid:4ed4d6cf-a11f-47a1-a714-1e35dd4e8d96","http://resolver.tudelft.nl/uuid:4ed4d6cf-a11f-47a1-a714-1e35dd4e8d96","Probabilistic Analysis of Velocity Distribution under Earth Embankments for Piping Investigation","Liu, K.; Hicks, M.A.; Vardon, P.J.; Jommi, C.","","2015","Piping has been attributed as a major cause of dam and embankment failures. Current national prediction models to predict piping use the hydraulic gradient between the upstream and downstream water levels as an indicator. They are deterministic and take no account of preferential pathways. However, piping usually initiates from a discrete downstream location and recent research indicates that piping happens when the water velocity reaches a critical value. The local velocity close to the downstream ground surface is strongly related to the inherent heterogeneity of the soil. This paper takes account of the spatial variability of hydraulic conductivity. Based on stochastic seepage analysis, local velocities in and under an embankment are computed. The results show that, when the coefficient of variation of hydraulic conductivity is small, the locations of the maximum local velocity from 500 realizations aggregate into a small area which is near the downstream toe of the embankment. In contrast, increasing the coefficient of variation scatters the possible locations of the maximum local velocity. Two typical situations are identified: one situation where the maximum local velocity is close to the downstream ground surface, and the other where the maximum local velocity is far from the downstream ground surface and located near the center of the foundation. In the first situation it is easier to reach the critical value to initiate piping because the maximum local velocity is near the ground surface, but it is also relatively easy to protect against. In contrast, in the second situation it is easier to form a passage for piping development once piping is initiated. This is due to the velocity towards the center of the foundation increasing.","piping investigation; velocity distribution; hydraulic conductivity; spatial variability; stochastic seepage","en","conference paper","","","","","","","","","","","","","",""
"uuid:3af81e37-f259-42f4-8670-58f4e1a2437c","http://resolver.tudelft.nl/uuid:3af81e37-f259-42f4-8670-58f4e1a2437c","Flow compensation in a MEMS dual-thermal conductivity detector for hydrogen sensing in natural gas","de Graaf, G. (TU Delft Electronic Instrumentation); Abarca Prouza, A.N. (TU Delft Electronic Instrumentation); Wolffenbuttel, R.F. (TU Delft Electronic Instrumentation)","Kenny, TW (editor); Bright, VM (editor)","2015","Conventional thermal conductivity detectors (TCDs) demonstrate a flow dependence. The approach presented here to reduce the flow dependence is based on the on-line flow compensation using two thin-film sensors on membranes in parallel on the same chip that are differentially operated. These are laterally identically, but with a different depth of the detection chamber, resulting in different quasi-static sensitivities to the thermal conductivity of the sample gas. The effects of conduction and convection in the structure have been studied using COMSOL Multiphysics. First prototypes have been fabricated and are presently tested.","Thermal conductivity; detector; flow compensation; Hydrogen sensor; MEMS","en","conference paper","IEEE Society","","","","","Accepted Author Manuscript","","","","","Electronic Instrumentation","","",""
"uuid:8d1ea6b9-d250-4b21-a6fa-589d2844305a","http://resolver.tudelft.nl/uuid:8d1ea6b9-d250-4b21-a6fa-589d2844305a","Single-Molecule Break Junctions Based on a Perylene-Diimide Cyano-Functionalized (PDI8-CN2) Derivative","Frisenda, R.; Parlato, L.; Barra, M.; Van der Zant, H.S.J.; Cassinese, A.","","2015","In this letter, we report the single-molecule conductance properties of a cyano-functionalized perylene-diimide derivative (PDI8-CN 2 ) investigated with gold nano-electrodes. This molecule is of large interest for the fabrication of high-performance and air-stable n-type organic field-effect transistors. Low-bias experiments performed on mechanically controllable break junctions reveal the presence of two different values of the single-molecule conductance, which differ by about two orders of magnitudes. Up to date, this feature was never observed for other perylene-diimide compounds having alternative chemical moieties attached to the basic aromatic core. Theoretical calculations suggest that the highest single-molecule conductance value here observed, comprised between 10 ?2 and 10 ?3 G 0 , is related to a charge transport path directly linking the two cyano groups.","perylene-diimide molecules; single molecule; break junctions; conductance; density functional theory; OA-Fund TU Delft","en","journal article","BioMed Central","","","","","","","","Applied Sciences","QN/Quantum Nanoscience","","","",""
"uuid:753ec916-cfc1-4a02-a1ea-bf3f39d310a5","http://resolver.tudelft.nl/uuid:753ec916-cfc1-4a02-a1ea-bf3f39d310a5","On the nonlinear thermomechanical behavior and delamination of conductive adhesives","Öztürk, B.","Ernst, L.J. (promotor); Jansen, K.M.B. (promotor)","2015","Adhesives based on thermoset polymers are used as thermal and electrical interfaces. These adhesives are filled with different particles in order to meet the requirements of heat transfer and electrical properties. Due to the reliability requirements of automotive applications, they are required to have excellent bulk and interface properties. Finite element analysis is used to locate stress and strain concentrations and to assess where the material is expected to fail. However, the accuracy of the design calculations is dependent on the validity of the material models used in the analysis. In this thesis, the limitations of the linear viscoelastic material model are discussed and a nonlinear viscoelastic material model is proposed. Although the experiments and the nonlinear viscoelastic modeling are illustrated for an adhesive, qualitatively similar results are also obtained for commercial molding compounds. For all test cases, when compared to the linear viscoelastic material model, the nonlinear viscoelastic material model is shown to improve the prediction of the experimental results. This will allow designers to perform quantitative FE simulations of adhesive joints. As adhesives join different materials together, the interface between the adjacent materials is the place where delamination related failure is most likely to occur. Since delamination also can initiate other failure mechanisms, such as electrical, thermal or mechanical failure mechanisms, the assessment of the risk of delamination has become an integral part of the reliability approach. Only very few studies focus on delamination of adhesive bonds. In this thesis, a new methodology to produce delamination specimens from existing products is described. Although the method is illustrated for two interfaces, wherein a single step of the production process is added, the approach makes it possible to examine different interfaces, which have the same processing properties as in the real product. The LTCC/adhesive and Alloy 42/adhesive interfaces are experimentally investigated for (near) mode I loading conditions. Finite element analysis (e.g. J-integral) is used to extract the energy release rate and the established critical value is implemented for cohesive zone modeling. The presented approach will allow delamination studies of interfaces between brittle materials (such as LTCC). The increased design complexity and the demand for reduced product development times require fast pre-qualification methods to assess the reliability of an adhesive bond and in order to obtain qualitative comparisons between different adhesive choices (e.g. material changes, surface preparations, etc.). In this thesis, a novel lap shear specimen, which is obtained by optimizing the standard geometry, is tested under cyclic loading. The test results, their meaning and their reliability are discussed. Suggestions are made to further improve the approach. The presented ""lap-shear"" test approach, on test samples from genuine products, can be used to assess the stability of the adhesive joints (For example, a Cu / lamination foil / CU - connection structure (not yet published), which can be used in next-generation power modules).","delamination testing; finite element analysis; adhesives; conductive adhesives; epoxy; lap shear; nonlinear viscoelasticity; linear viscoelasticity; mode mixity; tensile testing; constitutive modeling; product based experimentation; virtual doe; optimization","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Precision and Microsystems Engineering","","","",""
"uuid:10d18961-a23f-478e-b6e2-181d897d8541","http://resolver.tudelft.nl/uuid:10d18961-a23f-478e-b6e2-181d897d8541","Dielectric Strength and Thermal Conductivity of Mineral Oil based Nanofluids","Jin, H.","Smit, J.J. (promotor)","2015","In many applications of high voltage engineering, electrical and thermal stresses increase due to an ongoing decrease of product dimensions. In particular, the electrical industry is interested in applying nanofluids in transformers to be able to decrease transformer size and weight. The requirement for nanofluids is to enhance the electrical insulation as well as the thermal conductivity of transformer oil. The focus of this thesis is to investigate how to improve the dielectric strength and thermal conductivity of mineral oil by introducing a low concentration of nanoparticles as well as to understand the possible mechanism behind the property changes. Stable dispersed nanoparticles are vital for the investigation of the properties of nanofluids. However, it can be a challenge to maintain the nano-meter size of nanoparticles due to the attractive force between nanoparticles, which can lead to the formation of agglomerations which eventually settle out of suspension. In this thesis, good and stable dispersed nanoparticles in mineral oil have been achieved by magnetic stirring and ultrasonic vibration at a relatively low concentration. The two types of nanofillers which were used to achieve stable dispersed nanofluids are silica and fullerene nanoparticles. The results of AC breakdown test results on nanofluids with up to 0.02 wt.% silica and nanofluids with up to 0.1 wt.% fullerene showed that both types of nanofluids exhibited enhanced breakdown strength compared with mineral oil. The enhancement increases with an increase of mass fraction. The effect is more significant at higher moisture content. The enhancement of the AC breakdown voltage due to silica nanoparticles is larger than for fullerene nanoparticles. Since silica is an insulating material and fullerene is a semi conductive material, the phenomena can't be explained by the theory of conductive nanoparticles acting as electron traps. Besides, moisture content plays an important role in the breakdown behaviour of mineral oil. So one possible explanation behind the enhanced AC breakdown voltage of silica nanofluids is that moisture is adsorbed on the surface of silica nanoparticles. However, fullerene is hydrophobic, therefore moisture adsorption can't be the reason for the enhanced breakdown strength of fullerene nanofluids. Partial discharge (PD) measurements gave more detailed information on the pre-breakdown phenomenon of dielectric nanofluids by recording the discharge pulse shape, inception voltage, total discharge magnitude and single discharge pulse amplitude. The PD results of mineral oil, 0.01 wt.% silica and fullerene nanofluids showed that silica nanoparticles increase the inception voltage, and decrease both the total discharge magnitude and the pulse amplitude of mineral oil significantly. The effect due to fullerene nanoparticles is similar but less than the effect of silica nanoparticles. The possible explanation of this phenomenon is that organic acid is adsorbed on the surface of the nanoparticles. The increased inception voltage and decreased PD discharge magnitudes of silica and fullerene nanofluids can be due to the decreased acidity in the nanofluids. The larger effect of silica nanoparticles on the dielectric strength of mineral oil compared with fullerene nanoparticles can be a result of the combination of acid and moisture adsorption on the surface of the nanoparticles. The effect of silica and fullerene nanoparticles up to 0.1% mass fraction on the thermal conductivity and viscosity of mineral oil is negligible. This is mainly due to the low concentration and limitation of stability of nanofluids. The stability and possible harmful effects of nanoparticles on health and environment are also discussed in this thesis. Finally, it was concluded that the dielectric strength of mineral oil is improved by adding a low concentration of nanoparticles. The possible explanation for this achievement and recommendations for further research are also described.","nanofluids; silica; fullerene; breakdown strength; partial discharge; thermal conductivity","en","doctoral thesis","","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Electrical Power Engineering","","","",""
"uuid:79b51e32-7071-478b-ad0b-12ccac8f01bc","http://resolver.tudelft.nl/uuid:79b51e32-7071-478b-ad0b-12ccac8f01bc","Annealing of SnO2 thin films by ultra-short laser pulses","Scorticati, D.; Illiberi, A.; Bor, T.; Eijt, S.W.H.; Schut, H.; Römer, G.R.B.E.; De Lange, D.F.; Huis in 't Veld, A.J.","","2014","Post-deposition annealing by ultra-short laser pulses can modify the optical properties of SnO2 thin films by means of thermal processing. Industrial grade SnO2 films exhibited improved optical properties after picosecond laser irradiation, at the expense of a slightly increased sheet resistance [Proc. SPIE 8826, 88260I (2013)]. The figure of merit ? = T10 / Rsh was increased up to 59% after laser processing. In this paper we study and discuss the causes of this improvement at the atomic scale, which explain the observed decrease of conductivity as well as the observed changes in the refractive index n and extinction coefficient k. It was concluded that the absorbed laser energy affected the optoelectronic properties preferentially in the top 100-200 nm region of the films by several mechanisms, including the modification of the stoichiometry, a slight desorption of dopant atoms (F), adsorption of hydrogen atoms from the atmosphere and the introduction of laser-induced defects, which affect the strain of the film.","laser materials processing; ultrafast lasers; subwavelength structures; nanostructures; transparent conductive coatings; solar energy","en","journal article","Optical Society of America","","","","","","","","Applied Sciences","RST/Radiation, Science and Technology","","","",""
"uuid:864a6030-ad02-4c50-aeab-189bacb48259","http://resolver.tudelft.nl/uuid:864a6030-ad02-4c50-aeab-189bacb48259","Influence of Conductivity and Dielectric Constant of Water–Dioxane Mixtures on the Electrical Response of SiNW-Based FETs","Mescher, M.; Brinkman, A.G.M.; Bosma, D.; Klootwijk, J.H.; Sudhölter, E.J.R.; De Smet, L.C.P.M.","","2014","In this study, we report on the electrical response of top-down, p-type silicon nanowire field-effect transistors exposed to water and mixtures of water and dioxane. First, the capacitive coupling of the back gate and the liquid gate via an Ag/AgCl electrode were compared in water. It was found that for liquid gating smaller potentials are needed to obtain similar responses of the nanowire compared to back gating. In the case of back gating, the applied potential couples through the buried oxide layer, indicating that the associated capacitance dominates all other capacitances involved during this mode of operation. Next, the devices were exposed to mixtures of water and dioxane to study the effect of these mixtures on the device characteristics, including the threshold voltage (VT). The VT dependency on the mixture composition was found to be related to the decreased dissociation of the surface silanol groups and the conductivity of the mixture used. This latter was confirmed by experiments with constant conductivity and varying water–dioxane mixtures.","silicon nanowire; field-effect transistor; liquid gate; back gate; conductivity","en","journal article","MDPI","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:4a9569c2-1299-491f-b266-10ca9b18c376","http://resolver.tudelft.nl/uuid:4a9569c2-1299-491f-b266-10ca9b18c376","CSO pollution analysis based on conductivity and turbidity measurements and implications for application of RTC","Rombouts, P.M.M.; Schilperoort, R.; Langeveld, J.G.; Clemens, F.H.L.R.","","2013","The objective of this paper is to demonstrate the applicability of, and need for, surrogate sensors as robust sensors for water quality based RTC. For this purpose 1.5 years of level, conductivity (EC) and turbidity (TU) measurements at 9 combined sewer overflow (CSO) locations have been performed and analysed to determine the most polluted CSO locations. The analysis is based on surrogate event mean concentrations (sEMC, defined as EC multiplied by TU) and surrogate pollution loads (sPL, defined as the sEMC multiplied by the overflow volume). It is shown that EC and TU measurements can serve as surrogate measurements to determine the relative pollution of a CSO location. Analysis of the EC and TU values with respect to the distance between the CSO location and the WWTP gave no indication that this is of importance. Comparison of the sEMC and sPL for the CSO locations, shows that water quality measurements will have a great impact on the application of RTC, leading to quality based RTC.","Conductivity, Continuous monitoring, CSO, Quality based real time control, Turbidity","en","conference paper","s.n.","","","","","","","","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:36d9434e-1efa-4ad2-8990-78673b7794d3","http://resolver.tudelft.nl/uuid:36d9434e-1efa-4ad2-8990-78673b7794d3","Multiple healing in multi-functional polymer composites","Lafont, U.L.; Van Zeijl, H.; Van der Zwaag, S.","","2013","In this work, we investigate the formation of self-healing systems that are able to recover more than once more than one (mechanical or other physical) functionality. To this aim composites were created consisting of a polysulfide thermoset rubber matrix having intrinsic self-healing properties filled with thermally/electrically conductive particles. The cohesion, adhesion and thermal/electrical conduction recovery of these composites are investigated, monitored and quantified as function of the filler type and content. Moreover, the effects of healing temperature and the intrinsic polymer structure on the kinetics and degree of property recovery are explored.","composite; self-healing; dynamic bonding; adhesion; cohesion; thermal; conduction","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:7e2919b7-f164-40ca-a9a2-fd1e7b6d869f","http://resolver.tudelft.nl/uuid:7e2919b7-f164-40ca-a9a2-fd1e7b6d869f","Monitoring the restoration of interfacial contact for self healing thermal interface materials for LED and microelectronic applications","Lafont, U.L.; Van Zeijl, H.W.; Van der Zwaag, S.","","2013","While conventional self healing materials focus on the restoration of mechanical properties, newer generations of self healing materials focus on the restoration of other functional (i.e. non-mechanical) properties. Thermal conductivity is an example of an important functional property of a Thermal Interface Material (TIM) for LED’s and microelectronics devices. Current TIMs are optimized to provide thermal conductivity for as long a time as possible, yet these materials have no self healin potential and any crack formed will only lead to a decreased or lack of thermal conductivity and will dramatically reduce life time of the component. In order to get a better insight on how, as function of time, self-healing TIM systems are able to recover structural (cracks) and interfacial (delamination, adhesion) damages, we have developed a new specific technique to monitor local heat conduction. This technique probes very locally the heat transfer through the material to monitor changes related to heat conduction. If the material is damaged (cracked), the cracking or delamination will result in a thermal impedance restricting the thermal transfer. If the material is self healing, the local thermal conduction paths will be restored in time. In order to probe the thermal transfer for conventional and our new self healing TIM materials, a dedicated silicon chip containing an array of 49 diodes spaced uniformly over a 1 cm2 area has been fabricated. Using this device, it is possible to map with high spatial resolution the efficiency of the local thermal transfer and to relate it to the recovery of pre-imposed damage. Such experiments will yield unique local and temporal insight into cohesion and adhesion recovery of our self-healing polymeric systems.","self-healing; in-situ characterization; thermal conduction; interfacial damage recovery","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:6f0c3244-2636-4f57-9bb9-4b932b9332b1","http://resolver.tudelft.nl/uuid:6f0c3244-2636-4f57-9bb9-4b932b9332b1","Self-healing coatings based on electrochemical potential triggered release systems","Vimalanandan, A.; Lv, L.P.; Zhao, Y.; Crespy, D.; Landfester, K.; Rohwerder, M.","","2013","Abstract only.","corrosion; polymerization; inhibitor; semi-conducting polymers; scanning-Kelvin-probe","en","conference paper","","","","","","","","","","","","","",""
"uuid:91b7c6a5-593c-4534-ae79-93040a2f55f4","http://resolver.tudelft.nl/uuid:91b7c6a5-593c-4534-ae79-93040a2f55f4","Autonomous restoration of electrical interfaces","Sottos, N.R.; Kang, S.; Jones, A.E.; Okman, O.; Moore, J.S.; White, S.R.","","2013","Abstract only.","conductivity restoration; microcapsule; carbon black","en","conference paper","","","","","","","","","","","","","",""
"uuid:04cb799b-2a98-48d9-8fb6-811dc3e1f64f","http://resolver.tudelft.nl/uuid:04cb799b-2a98-48d9-8fb6-811dc3e1f64f","Redox-responsive release of self-healing agent for anticorrosion","Lv, L.P.; Zhao, Y.; Vimalanandan, A.; Rohwerder, M.; Landfester, K.; Crespy, D.","","2013","Abstract only.","capsule; conducting polymer; redox-responsive; self-healing","en","conference paper","","","","","","","","","","","","","",""
"uuid:4c1c86ac-cefc-4958-a4ec-1062998951d9","http://resolver.tudelft.nl/uuid:4c1c86ac-cefc-4958-a4ec-1062998951d9","Monitoring the restoration of interfacial contact for self healing thermal interface materials for LED and microelectronic applications","Lafont, U.; Van Zeijl, H.W.; Van der Zwaag, S.","","2013","While conventional self healing materials focus on the restoration of mechanical properties, newer generations of self healing materials focus on the restoration of other functional (i.e. non-mechanical) properties. Thermal conductivity is an example of an important functional property of a Thermal Interface Material (TIM) for LEDs and microelectronics devices. Current TIMs are optimized to provide thermal conductivity for as long a time as possible, yet these materials have no self healing potential and any crack formed will only lead to a decreased or lack of thermal conductivity and will dramatically reduce life time of the component. In order to get a better insight on how, as function of time, self-healing TIM systems are able to recover structural (cracks) and interfacial (delamination, adhesion) damages, we have developed a new specific technique to monitor local heat conduction. This technique probes very locally the heat transfer through the material to monitor changes related to heat conduction. If the material is damaged (cracked), the cracking or delamination will result in a thermal impedance restricting the thermal transfer. If the material is self healing, the local thermal conduction paths will be restored in time. In order to probe the thermal transfer for conventional and our new self healing TIM materials, a dedicated silicon chip containing an array of 49 diodes spaced uniformly over a 1 cm2 area has been fabricated. Using this device, it is possible to map with high spatial resolution the efficiency of the local thermal transfer and to relate it to the recovery of pre-imposed damage. Such experiments will yield unique local and temporal insight into cohesion and adhesion recovery of our self-healing polymeric systems.","self-healing; in-situ characterization; thermal conduction; interfacial damage recovery","en","conference paper","","","","","","","","","","","","","",""
"uuid:c62d57ed-30ae-4738-b68c-ace2b34e10f8","http://resolver.tudelft.nl/uuid:c62d57ed-30ae-4738-b68c-ace2b34e10f8","Multiple healing in multi-functional polymer composites","Lafont, U.; Van Zeijl, H.; Van der Zwaag, S.","","2013","In this work, we investigate the formation of self-healing systems that are able to recover more than once more than one (mechanical or other physical) functionality. To this aim composites were created consisting of a polysulfide thermoset rubber matrix having intrinsic self-healing properties filled with thermally/electrically conductive particles. The cohesion, adhesion and thermal/electrical conduction recovery of these composites are investigated, monitored and quantified as function of the filler type and content. Moreover, the effects of healing temperature and the intrinsic polymer structure on the kinetics and degree of property recovery are explored.","composite; self-healing; dynamic bonding; adhesion; cohesion; thermal conduction","en","conference paper","","","","","","","","","","","","","",""
"uuid:b422dc42-ebaf-42b2-add3-acc7daa9c528","http://resolver.tudelft.nl/uuid:b422dc42-ebaf-42b2-add3-acc7daa9c528","Thermal conductivity of low temperature grown vertical carbon nanotube bundles measured using the three-? method","Vollebregt, S.; Banerjee, S.; Beenakker, K.; Ishihara, R.","","2013","The thermal conductivity of as-grown vertical multi-walled carbon nanotubes (CNT) bundles fabricated at low temperature (500?°C) was measured using a vertical 3?-method. For this, CNT were selectively grown inside an oxide opening and sandwiched between two metal electrodes. The validity of the method was confirmed by both measurements as simulations. The measured thermal conductivity of 1.7-3.5?W/mK is significantly lower than values reported before, which is caused by the low quality of the tubes. This clearly indicates that tube quality will be essential when integrating CNT.","carbon nanotubes; electrodes; nanofabrication; thermal conductivity","en","journal article","American Institute of Physics","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Microelectronics","","","",""
"uuid:68de6b3d-9eb4-4ac6-8692-697d54e922de","http://resolver.tudelft.nl/uuid:68de6b3d-9eb4-4ac6-8692-697d54e922de","Molecular modeling in design of polyaniline for polymer-based carbon dioxide sensor","Chen, X.P.","Zhang, G.Q. (promotor)","2013","Conducting polymers are attractive chemical sensing materials due to their outstanding characteristics including low cost, room-temperature operations, easy device fabrication, high sensitivity and short response time. The new nanowires architecture, with high surface-to-volume ratio, makes possible the conducting polymers an ultra fast detection of chemical at low concentrations. Polymer-coated nanowires are thus the potential cost effective solution for the new generation gas sensors. As a sensing material, the molecular design of the conducting polymer is utterly important. The conductive polymers can be tailored to fulfill the sensing requirement by its modifying functional groups in accordance to the applications. Molecular modeling which predicts the material properties of conductive polymers helps in the design of the sensor material. In this thesis, I present a molecular modeling approach to design and evaluate conducting polymer as chemical sensing material for polymer nanowire or polymer-coated nanowire carbon dioxide (CO2) sensors in greenhouse application. In order to provide an overview of the rapid progress in the application of chemical sensing materials with nanowire architecture, literature study on nanowire gas sensors has been presented in the Chapter 2. A comparison between the two basic approaches (top-down and bottom-up) in the nanowire synthesis is given. The sensing principles and configurations of nanowire gas sensors with their relevant assembly technologies are summarized. Based on the review work, a polyaniline-coated nanowire field-effect transistor (NanoFET) is proposed for CO2 sensing system in greenhouse. This sensor set combines the advantages of nanowire architecture, FET sensor configuration and conducting polymers. A crucial part of any molecular simulation study is the choice of forcefields. In Chapter 3, we evaluate the validity of COMPASS and PCFF forcefields in predicting the physical and thermophysical properties of amorphous polymer emeraldine based polyaniline (EB–PANI). A combination of molecular mechanics (MM) and molecular dynamics (MD) analysis is employed to determine the polymer’s properties, including density (?) and solubility parameter (?). The temperature dependence of specific volume (?), non-bond energy (Enon-bond) and solubility parameters are used to estimate the glass transition temperature (Tg). Comparing the simulation results with experimental data, the accuracy of forcefields (COMPASS and PCFF) is elucidated. The COMPASS forcefield has been demonstrated as a better forcefield which provides a closer agreement with experiment data than the PCFF. Thus, the molecular modeling design of PANI for CO2 sensing is conducted by using the COMPASS forcefield. For effective sensing, the dissolution of an analyte, as quantified as the solubility parameter ?, in the sensing materials is crucial. Understanding of the temperature dependence of solubility parameter can provide adequate information for the sensitivity issue induced as the temperature changes. In Chapter 4, I have developed a compact model to describe the solubility parameter change due to the temperature impacts. It is showing that in the working temperature range of greenhouse, the temperature impact on the solubility parameter is limited and can be neglected. To verify the accuracy of our calculation, two kind of analysis has been are performed: (i) the ? value at 298 K for EB–PANI is predicted and compared with the literature reported data; (ii) the Tg of the polymer is determined from the ?–T curve and compared with the experimental value. The temperature dependence of solubility parameter of the EB-PANI has been determined by molecular modeling approach. The sensing mechanism of the PANI for CO2 materials is based on protonic acid doping. Molecular modeling of the sensing mechanism can offer useful information for the sensitivity and the selectivity of PANI. In Chapter 5, a compact model has been developed to describe the protonic acid doping of PANI with reasonable accuracy. The atomistic model is developed by using a statistical thermodynamic analysis method. The molecular modeling method is comprised of three key steps: (i) developing the atomistic models; (ii) defining the doing criteria; and (iii) simulating the protonic acid doping. By using the molecular model, the relationships including pKa/pH and doping percentage/pH are established. The computed results compare favorably with the reported experimental data. The change of charge carrier density causes the changes in the conductivity of the gas-sensitive conducting polymers. Thus, the relationship between macroscopic conductivity and charge carrier density is very useful in the design and evaluation of PANI as chemical sensing materials. In Chapter 6, by using the molecular model derived from Chapter 5, the relationships include the charge carrier density/pH and the conductivity/charge carrier density of EB-PANI are established properly. It is to find that the conductivity has an exponential function relationship with the charge carrier density [? = (A*n)a] in PANI. Using the computing relationship of conductivity/charge carrier density, the sensitivity of EB-PANI and its derivative K-SPANI for the detection of HCl is evaluated. The finding shows that by introducing function groups (–SO3K), the sensitivity of K-SPANI is greatly improved by two times. Thus the conducting polymer K-SPANI is a good candidate for acidic gas sensing, such as HCl, H2S, or CO2 in high humidity conditions. With the fundamental knowledge established in Chapters 3-6, the molecular design of PANI for greenhouse CO2 gas sensing can be achieved. Chapter 7 investigates the effect of functional group on the working range of polyaniline sensors for CO2 in agriculture industry. The humidity, temprature and the concentration of CO2 in the tightly clad greenhouses have been considered in the molecular model. The work compares the response of the pure EB, the polymer mixture of EB-PANI and undoped sodium sulfonated polyaniline (NaSPANI) with sulfur to nitrogen ratio (S/N) of 0.6, 0.5 and 0.4 to CO2. Under the working condition in a greenhouse, the working range of NaSPANI has been estimated as ~ [102- 104] ppm which demonstrates it is a good candidate for CO2 detection in agricultural industry. In considering the synthetic difficulty, I propose the conducting polymer NaSPANI (S/N = 0.5) is a good candidate for agricultural CO2 sensing. In summary, a molecular modeling method which helps in the design and evaluation of conductive polymers for carbon dioxide sensing in greenhouses has been established. This thesis work contributes at use of computational approaches in designing and optimizing chemical sensing materials for various applications.","molecular modeling; polyaniline; carbon dioxide sensor; nanowire nanosensor; conducting polymer","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Precision and Microsystems Engineering","","","",""
"uuid:06d1d50f-2ff8-48e2-a2b9-a459775114c7","http://resolver.tudelft.nl/uuid:06d1d50f-2ff8-48e2-a2b9-a459775114c7","Charge carrier transport at the nanoscale: Electron and hole transport in self-assembled discotic liquid crystals: Mobile ionic charges in nanocomposite solid electrolytes","Haverkate, L.A.","Mulder, F.M. (promotor)","2013","This thesis explores some fundamental aspects of charge carrier transport at the nanoscale. The study is divided in two parts. In the first part, the structural, dynamical and vibrational properties of discotic liquid crystals are studied in relation to the potential of these self-assembled ‘mesophases’ to form molecular conducting wires. Although the study is fundamental in nature, a direct link will be made to the potential of discotic liquid crystals for opto-electronic applications such as solar cells. The second part presents a study on the interfacial defect chemistry in nano-structured solid acids. This part addresses the issue of interface-dominated charge transport in nano-sized materials. The heart of the work is a theoretical framework that explains the strong enhancement of proton conductivities observed when solid acids such as CsHSO4 or CsH2PO4 are blended with TiO2 or SiO2 nanoparticles. The results are of fundamental interest for the development of solid state ionic conductors that can be used as electrolytes in batteries and fuel cells.","discotic liquid crystals; solid state electrolytes; nanoionics; organic electronics; Neutron scattering; NMR; DFT; conductivity; solid acids; fuel cell; batteries; solar cells","en","doctoral thesis","","","","","","","","2013-03-30","Applied Sciences","Radiation, Radionuclides & Reactors","","","",""
"uuid:02d7988d-baf2-4c30-8396-4c21526d253e","http://resolver.tudelft.nl/uuid:02d7988d-baf2-4c30-8396-4c21526d253e","Determining the transition between DWF and WWF based on water quality measurements","van Daal-Rombouts, P.M.M. (TU Delft Sanitary Engineering; Witteveen+Bos); Langeveld, J.G. (TU Delft Sanitary Engineering; Royal HaskoningDHV); Clemens, F.H.L.R. (TU Delft Sanitary Engineering; Deltares)","","2013","","conductivity; continuous monitoring; dry weather flow; turbidity; wet weather flow","en","conference paper","","","","","","","","","","","Sanitary Engineering","","",""
"uuid:4220e3ee-bdcb-4a46-ade1-470d3c2ad6da","http://resolver.tudelft.nl/uuid:4220e3ee-bdcb-4a46-ade1-470d3c2ad6da","On the Scalar Scattering Theory for Thin-Film Solar Cells","Jäger, K.","Zeman, M. (promotor)","2012","Nano-textured interfaces between two media of different refractive indices scatter light. The angular distribution and the intensity of the scattered light are deter- mined by the geometry of the nano-textures and the difference of the refractive indices of the two media. Thin-film silicon solar cells (TFSSC), which convert sunlight directly into electricity, have nano-textured interfaces. These interfaces scatter the light incident on the solar cell. The scattering leads to a longer average path length of the photons in the absorber layer of the solar cell. Therefore more light can be absorbed and thus converted to electricity. To introduce nano-textured interfaces into the solar cells, usually transparent conductive oxide (TCO) layers are used. Some TCO materials obtain nano-textured surfaces during the production process, while others are made rough by post processing, e.g. by etching. Nano-textures have been successfully implemented in TFSSC for almost 30 years by academia and industry; however, theoretical investigations on the relation between the nano-textures and the scattered electromagnetic fields have only been performed for about ten years. It is very important to investigate how the nano-textures can be optimized for scattering. In this thesis a scattering model is developed to tackle this important problem. The scattering model is based on the scalar scattering theory, i.e. it neglects the vector- character of the electromagnetic field and thus the light. Despite this strong assumption we have demonstrated that the model is suitable for simulating descriptive parameters of the scattered field in both reflection and transmission. The model is based on the fact that the transmitted field behind the nano-texture and the scattered field are related via Fourier transforms. By making simple assumptions for the transmitted field the model can be implemented using Fast Fourier trans- form algorithms, i.e. the model is very fast. The scattering model is formulated such that in principle it works for rough interfaces between arbitrary materials. We successfully evaluated it for several of these interfaces. We further showed that the model is also able to produce first predictions for the scattering parameters at oblique incidence. However, in this case the deviations between measured and simulated values are larger. Combining the scattering model with the ASA opto-electrical device simulator allows predicting how the nano-textures affect the performance of solar-cells. This combination can also be used to perform the major motivation for the development of scattering models: To investigate how the morphology of the nano- textures can be optimised. For this optimisation we use the “simulated annealing” optimisation algorithm. The optimisation and a subsequent evaluation reveal that the lateral feature size of the nano-textures is crucial for scattering into large angles: The smaller the lateral feature size, the more light is scattered into large angles. If, however, the lateral feature size becomes too small, less light is scattered since the nano texture then appears as effective medium. The vertical feature size hardly influences the shape of the scattered field. Nonetheless, it determines the fraction of the total light that is scattered away from the specular direction. If the rms-roughness, a measure for the vertical modulation of the texture, is kept constant, a nano- texture with the optimal lateral feature size is preferable to a texture that consists of a superposition of textures with different lateral feature sizes. However, due to the effect of the nano-textures on the electrical properties of the solar cells, a superposition of a texture consisting of large lateral and vertical features with another texture with small lateral and vertical features is preferable to a texture consisting of small lateral but large vertical features, i.e. sharp spikes. The results of our work give the direction to push absorption in solar cells towards the theoretical limits.","thin-film silicon solar cells; scattering model; transparent conducting oxides; photovol","en","doctoral thesis","","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Electrical Sustainable Energy","","","",""
"uuid:5b0eb1b3-ec47-4b92-95f9-688cf8e284e0","http://resolver.tudelft.nl/uuid:5b0eb1b3-ec47-4b92-95f9-688cf8e284e0","Competition between social and market renting: A theoretical application of the structure-conduct-performance paradigm","Lennartz, C.; Haffner, M.; Oxley, M.","","2012","Housing policies in many countries have become more market orientated as the role of governments has shifted from the direct supply and funding of non-market housing towards the role of a regulator and facilitator. Central to this development is the notion that providers of social housing have to become more competitive. Arguably, these social housing changes have important implications for the relationship between social and market rented housing and thus the rental market as a whole. Conceptual frameworks that facilitate the understanding of this relationship are sparse commodities. This paper seeks to develop a theoretical framework that can be used to shed light on the conditions, processes, and effects of the new relation between the two rental tenures from an economic competition viewpoint. Therefore, this paper adapts the structure-conduct-performance paradigm to rented housing and discusses the framework’s applicability and value on a theoretical level.","competition; structure-conduct-performance paradigm; rental housing markets; social housing; private renting","en","journal article","Springer-Verlag","","","","","","","","OTB Research Institute for the Built Environment","OTB Research","","","",""
"uuid:ac907049-96d0-4304-a5d1-5b2661741ab1","http://resolver.tudelft.nl/uuid:ac907049-96d0-4304-a5d1-5b2661741ab1","Photogeneration Diffusion and Decay of Charge Carriers in Quantum-Dot Solids","Gao, Y.","Siebbeles, L.D.A. (promotor); Van der Zant, H.S.J. (promotor)","2012","Semiconductor nanocrystals (NCs), which can have a variety of sizes, shapes and chemical compositions, will be a large and important family of future advanced materials.This thesis focuses on colloidal semiconductor NC solids, also called quantum-dot (QD) solids, which are promising materials for many applications, such as photo-detectors, field-effect transistors, solar cells, light-emitting diodes, and lasers. The thesis presents studies on the charge carrier properties of PbSe QD solids, going through the charge carrier photogeneration, thermalization, diffusion and decay, which together are the ``life and fate'' of the charge carriers. Diverse tools have been utilized to reveal the whole picture of the ``life and fate''. The most important ones are: femtosecond transient absorption spectroscopy (TA) (Chapter 2, 3, 4), picosecond Terahertz spectroscopy (THz) (Chapter 2), the nanosecond time-resolved microwave conductivity technique (TRMC) (Chapter 2-5), and Monte Carlo simulations (Chapter 4).","quantum dot; Auger Decay; charge carrier conductivity; semiconductor","en","doctoral thesis","Posen & Looijen","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:d668be08-30ea-47fd-a09f-b1954cfdc53d","http://resolver.tudelft.nl/uuid:d668be08-30ea-47fd-a09f-b1954cfdc53d","Formation and control of wrinkles in graphene by the wedging transfer method","Calado, V.E.; Schneider, G.F.; Theulings, A.M.M.G.; Dekker, C.; Vandersypen, L.M.K.","","2012","We study the formation of wrinkles in graphene upon wet transfer onto a hydrophilic target substrate, whereby draining of water appears to play an important role. We are able to control the orientation of the wrinkles by tuning the surface morphology. Wrinkles are absent in flakes transferred to strongly hydrophobic substrates, a further indication of the role of the interaction of water with the substrate in wrinkle formation. The electrical and structural integrity of the graphene is not affected by the wrinkles, as inferred from Raman measurements and electrical conductivity measurements.","electrical conductivity; graphene; Raman spectra; surface morphology","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Quantum Nanoscience","","","",""
"uuid:4ddd28eb-409e-492a-a1f4-3a7af1e18b41","http://resolver.tudelft.nl/uuid:4ddd28eb-409e-492a-a1f4-3a7af1e18b41","Bench-scale centrifuge testing to determine the hydraulic conductivity of clayey soils","Di Emidio, G.; Peiffer, H.; Malengier, B.; Kison, P.; Bezuijen, A.","","2012","The purpose of this research is to validate a mathematical model for flow through saturated and unsaturated porous media using a bench-scale centrifuge for an accurate determination of the hydraulic conductivity (function of the saturation degree of a soil) within a limited time at a reasonable price. The aim of this paper is to show preliminary results of this investigation where the validation and calibration of the mathematical model is performed determining the hydraulic conductivity of saturated porous media, such as kaolin clay and glass porous filters, with a bench-scale centrifuge.","centrifuge modeling; hydraulic conductivity; inverse problem","en","conference paper","","","","","","","","","","","","","",""
"uuid:0d8eb6d1-9919-448b-b222-d8dec5528ff1","http://resolver.tudelft.nl/uuid:0d8eb6d1-9919-448b-b222-d8dec5528ff1","Revisiting the melting temperature of NpO2 and the challenges associated with high temperature actinide compound measurements","Böhler, R.; Welland, M.J.; De Bruycker, F.; Boboridis, K.; Janssen, A.; Eloirdi, R.; Konings, R.J.M.; Manara, D.","","2012","This work revisits the melting behaviour of neptunium dioxide, an actinide compound which can be produced in the nuclear fuel during operation, and which has an important impact on the nuclear fuel and waste radioactivity especially on the very long term. The present experimental approach employs remote laser heating under controlled atmosphere and fast pyrometry. This technique circumvents problems encountered by more traditional heating techniques, in particular, the reaction between sample and containment at temperatures beyond 2500 K. In addition, only a small amount of sample material is required, which is an advantage with respect to the radioactivity and limited availability of neptunium. The NpO2 melting/freezing temperature has been measured to be 3070 K?±?62 K, much higher than previous values (around 2830 K) obtained by more traditional thermal analysis methods. The large amount of experimental data collected allowed a consistent statistical analysis. It seems likely, although not fully evident from the present results, that the high oxygen potential at temperatures around melting leads to a slightly hypo-stoichiometric congruent melting composition, as already observed in other actinide (ThO2, PuO2) and lanthanide oxides (e.g., CeO2). Finally, a recently developed phase-field model was used for the simulation of the observed thermograms, allowing a deeper insight in material properties that are difficult to directly measure. For example, a polaron contribution to the high-temperature thermal conductivity, well accepted for the commonly studied actinide oxide UO2, is shown here to likely be present in NpO2.","freezing; heat treatment; melting; neptunium compounds; polarons; thermal analysis; thermal conductivity","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","RRR/Radiation, Radionuclides and Reactors","","","",""
"uuid:5fbea9e8-2b30-4fd2-800a-d72651a6f856","http://resolver.tudelft.nl/uuid:5fbea9e8-2b30-4fd2-800a-d72651a6f856","Electrical Survey of Peat Deposits","Ponziani, M.","Slob, E.C. (promotor)","2012","","Peat; Electrical Conductivity; Consolidation","en","doctoral thesis","","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:0fd14767-75a2-4593-a2d5-a7b2e3451d74","http://resolver.tudelft.nl/uuid:0fd14767-75a2-4593-a2d5-a7b2e3451d74","Thermal and Electrical Properties of Nanocomposites, Including Material Properties","Kochetov, R.","Smit, J.J. (promotor)","2012","The research described in this thesis is part of a state-funded IOP-EMVT project in cooperation with industrial companies, aiming at the design, assessment and implementation of new, environmental friendly (e.g. oil and SF6 - free) solid dielectric materials. A large disadvantage of solid polymer dielectrics is their relatively low thermal conductivity. Therefore, the focus in this thesis is on if and how nanotechnology can improve the thermal conductivity without deteriorating existing electrical properties. Epoxy resin, which is very common polymer material in the electrical and power industry, has been used as a host to create new insulating materials: nanocomposites. In order to improve the thermal conductivity of epoxy resin, thermally conducting but electrically insulating nanofillers, such as aluminum and magnesium oxides (Al2O3 and MgO), silicon dioxide (SiO2), boron and aluminum nitrides (BN and AlN) were used to dope the polymer matrix. Good compatibility and adhesion was achieved by surface modification of the nanoparticles, using a silane coupling agent. Proper dispersion of nanoparticles is a vital factor for the final properties of nanocomposites. Good and stable dispersion of nanoparticles in polymer matrices have been achieved by mechanical mixing and ultrasonic vibration. The quality of the dispersion of nanoparticles was satisfactory for most of the nanocomposite samples. The fabricated composites were classified into three types, according to the average particle size and the extent of agglomerates observed inside the polymer matrix. Dielectric spectroscopy revealed that the relative permittivity of many nanocomposites is lower than that of the pure epoxy. This surprises, since the relative permittivity of the bulk materials of the fillers used is higher than that of the epoxy. The anomalous dielectric behaviour of nanocomposites was explained by the existence of an interface layer between polymer matrix and inorganic filler, and its influence on the macroscopic properties of the composite. The dielectric spectroscopy investigations demonstrated a reduction of the real and imaginary parts of the complex permittivity for all samples after subjecting the samples to postcuring. The postcuring process leads to evaporation of absorbed water and finalizes the process of epoxy curing. It was postulated that the interface polymer volume, which is affected by the alignment of polymer chains around surface treated nanoparticles, conducts the heat much better than an amorphous polymer that is not altered by nanoparticles. We proposed a three-phase Lewis-Nielsen model to fit the thermal conductivity behaviour of nanocomposites, which have a third phase of aligned polymer layers. The model fits the experimental data very well and takes the thermal resistance of the interface into account. Besides the interfacial layer and its nature, the size of the particles, their aspect ratio, crystal structure and alignment inside the polymer as well as surface modification are important aspects in determining the thermal conductivity of composites. Several ways are proposed to optimize the nanocomposite processing to enable scaling up to large industrial volumes. Finally, possible harmful effects of nanoparticles on health and required precautions for the workplace are discussed in the course of this thesis.","nanocomposite; surface treatment; epoxy resin; thermal conductivity; relative permittivity","en","doctoral thesis","","","","","","","","","Electrical Engineering, Mathematics and Computer Science","High Voltage Technology & Managenment","","","",""
"uuid:b30a4354-3fa9-4ab3-845a-67810295fafe","http://resolver.tudelft.nl/uuid:b30a4354-3fa9-4ab3-845a-67810295fafe","Thermal ideality factor of hydrogenated amorphous silicon p-i-n solar cells","Kind, R.; Van Swaaij, R.A.C.M.M.; Rubinelli, F.A.; Solntsev, S.; Zeman, M.","","2011","The performance of hydrogenated amorphous silicon (a-Si:H) p-i-n solar cells is limited, as they contain a relatively high concentration of defects. The dark current voltage (JV) characteristics at low forward voltages of these devices are dominated by recombination processes. The recombination rate depends on the concentration of active recombination centers and the recombination efficacy of each of these centers. The first factor causes the ideality factor of the devices to be non-integer and to vary with voltage. The temperature dependence of the dark current can be expressed by its activation energy. For microcrystalline silicon solar cells the activation energy varies with voltage with a so-called thermal ideality factor of 2. This value was derived for devices with a spatially uniform defect distribution and reflects the recombination efficacy. Here we present results of a thickness series of a-Si:H p-i-n solar cells. We have matched the experimental curves with computer simulations, and show that the voltage-dependent ideality factor curve can be used to extract information on the cross sections for electron and hole capture. Also, the activation energy is used as a measure for the mobility gap, resulting in a mobility gap for a-Si:H of 1.69?eV. We find a thermal ideality factor close to 2 for all samples. This is explained with a theoretical derivation, followed by a comparison between the internal electric field strength and the spatial variation of the defect density in the intrinsic layer. The thermal ideality factor is shown to be insensitive to the defect distribution and the recombination profile in the device. It is, therefore, an appropriate parameter to characterize a-Si:H p-i-n devices, providing direct insight on the recombination efficacy.","amorphous semiconductors; crystal defects; dark conductivity; electron mobility; electron traps; electron-hole recombination; elemental semiconductors; hole mobility; hole traps; hydrogen; silicon; solar cells","en","journal article","American Institute of Physics","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Electrical Sustainable Energy","","","",""
"uuid:f50e0b0e-f855-4566-aa72-3d3e9fc50d12","http://resolver.tudelft.nl/uuid:f50e0b0e-f855-4566-aa72-3d3e9fc50d12","Sensor platform for gas composition measurement","De Graaf, G.; Bakker, F.; Wolffenbuttel, R.F.","","2011","The gas sensor research presented here has a focus on the measurement of the composition of natural gas and gases from sustainable resources, such as biogas. For efficient and safe combustion, new sensor systems need to be developed to measure the composition of these new gases. In general about 6 gas components need to be measured to determine the caloric value and the combustion properties of these gas mixtures. The concentration levels of the relevant components are relatively high, and the emphasis of this research work is therefore on selectivity and avoidance of cross contamination. For this reason and because of their limited stability, chemical sensors are not considered. The sensors in this work are based on physical interaction with the gas. One single sensing principle is insufficient for identification of all components in the natural gas and a microsystem for measuring three different physical properties of the gas components are proposed in this work: thermal conductivity, optical and photo-acoustic infrared absorption.","gas sensor platform: NDIR; photoacoustic gas sensor; thermal conductivity detector; natural gas composition measurement","en","journal article","Elsevier","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Microelectronics","","","",""
"uuid:aef95560-b82b-43bc-8a6d-df8c13c3b51b","http://resolver.tudelft.nl/uuid:aef95560-b82b-43bc-8a6d-df8c13c3b51b","Thermal conductivity of microPCMs-filled epoxy matrix composites","Su, J.F.; Wang, X.Y; Huang, Z.; Zhao, Y.H.; Yuan, X.Y.","","2011","Microencapsulated phase change materials (microPCMs) have been widely applied in solid matrix as thermal-storage or temperature-controlling functional composites. The thermal conductivity of these microPCMs/matrix composites is an important property need to be considered. In this study, a series of microPCMs have been fabricated using the in situ polymerization with various core/shell ratio and average diameter; the thermal conductivity of microPCMs/epoxy composites were investigated in details. The results show that the microPCMs have smooth surface and regular global shape with compact methanol–melamine–formaldehyde shell. The shell thickness does not greatly influence the phase change behaviors of PCM. Moreover, smaller microPCMs embedded in epoxy can improve the thermal transmission ability of composites. The effect of thermal conductivity of composites can be improved with higher volume fraction (10–30%) of microPCMs; and smaller size microPCMs with the same content of PCM may also enhance the thermal transmission area in matrix. Modeling analysis of relative thermal conductivity indicates that mixing higher thermal conductivity additive in PCM or matrix is an appropriate method to improve the thermal conductivity of microPCMs/matrix composites.","microcapsules; phase change materials; thermal conductivity; epoxy; composites","en","journal article","Springer-Verlag","","","","","","","","Civil Engineering and Geosciences","Design and Construction","","","",""
"uuid:9cb199a4-6359-4c73-a053-8cd57fc5d703","http://resolver.tudelft.nl/uuid:9cb199a4-6359-4c73-a053-8cd57fc5d703","Charge Carriers and Excited States in Supramolecular Materials","Patwardhan, S.","Siebbeles, L.D.A. (promotor)","2011","The field of organic electronics has been thriving for the last decades due to growing commercial interest. One of the advantages of using organic materials as semiconductors is the possibility to tune their optoelectronic properties by modifying the chemical structure and organization of the building blocks. In this thesis, the properties of charge carriers and excited states in a variety of organic supramolecular materials were studied in relation to the chemical structure and organization of their building blocks. The charge transport properties were studied by pulse radiolysis time-resolved microwave conductivity (PR-TRMC) measurements and theoretical calculations. The excited state properties were investigated by combining optical spectroscopy with exciton theory calculations.","supramolecular electronics; charge transport; excited states; chlorophylls; DNA; covalent organic framework; liquid crystal; time-resolved microwave conductivity; exciton theory","en","doctoral thesis","Ipskamp Drukkers B.V.","","","","","","","2011-08-01","Applied Sciences","Chemical Engineering","","","",""
"uuid:fb992a64-6a35-4c1e-ad5a-bdb5d8efa746","http://resolver.tudelft.nl/uuid:fb992a64-6a35-4c1e-ad5a-bdb5d8efa746","Effects of the airwave in time-domain marine controlled-source electromagnetics","Hunziker, J.W.; Slob, E.C.; Mulder, W.","","2011","In marine time-domain controlled-source electromagnetics (CSEM), there are two different acquisition methods: with horizontal sources for fast and simple data acquisition or with vertical sources for minimizing the effects of the airwave. Illustrations of the electric field as a function of space and time for various source antenna orientations, based on analytical formulation of the electric field in two half-spaces, provide insights into the properties of the airwave and the nature of diffuse electric fields. Observing the development of the electric field over time and space reveals that diffusive fields exhibit directionality. Therefore, techniques that have thus far mostly been applied to wavefields can be adapted for CSEM. Examples range from the well-known up-down decomposition to beam steering. Vertical sources have the advantage of not creating an airwave. On the other hand, it is quite difficult to achieve perfect verticality of the source antenna. Results, using a numerically modeled data set to analyze the impact of the airwave on a signal from a subsurface reservoir in the case of a slightly dipping vertical source, indicate that already for a dip of 0.05, the airwave contributes 20% to the complete electric field in our configuration of reservoir depth, water thickness, and conductivity values.","antennas; data acquisition; electrical conductivity; geophysical equipment; geophysical prospecting; hydrocarbon reservoirs; rocks; seafloor phenomena","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:38665fe2-7c4c-47da-a94d-d1dd7fad84eb","http://resolver.tudelft.nl/uuid:38665fe2-7c4c-47da-a94d-d1dd7fad84eb","Structure and dynamics of hydrogen in nanocomposite solid acids for fuel cell applications","Chan, W.K.","Mulder, F.M. (promotor)","2011","The transition to sustainable energy sources is inevitable. A possible future scenario could be the hydrogen economy, where the fuel cell plays an important role in the conversion of hydrogen back to electricity. The technology behind the fuel cell however, still has significant room for improvement. A next step would be the realization of so called intermediate temperature fuel cells. Solid acids have been shown to be promising candidates for fuel cell electrolytes as they possess high proton conductivity in the intermediate temperature range, from ambient up to 250 °C. One major problem of the solid acids was the low proton conduction at temperatures below their superprotonic phase transition. This has been solved by nanostructuring the materials, where the solid acid is mixed with e.g. TiO2 or SiO2 nanoparticles of 40 nm in size and smaller. The conductivity increases with orders of magnitude. Here a multi-technique approach is used to study this matter. Using Neutron Diffraction, direct experimental proof of the occurrence of space charge effects in these nanocomposites was shown in the form of deuterium ion intercalation in TiO2 nanoparticles together with deuterium depletion in the solid acid CsHSO4 phase. Very high, particle size dependent proton densities, up to 10% in the 7 nm TiO2 particles were found. Quasi elastic neutron scattering experiments showed fractions of up to 25% of the hydrogen ions at temperatures below the superprotonic phase transition to possess mobilities similar to the protons above this transition. Nuclear magnetic resonance spectroscopy showed similar fractions as well as T1 relaxation times of roughly 2 orders of magnitude shorter compared to the bulk crystalline solid acids. These results lead to the conclusion that because of the space charge effect, vacancies are created in the solid acid at temperatures below the superprotonic phase transition temperature. These empty sites allow a large fraction of the hydrogen ions to move, to such an extent that they become almost as mobile as in the superprotonic phase. Furthermore a composite electrolyte of CsHSO4 and Nafion was synthesized. The composite electrolyte membrane showed good mechanical strength resulting from the Nafion polymer matrix. It exhibited similar proton conductivity to pure Nafion at low temperatures in a humid environment and showed high conductivity of 10-3 S/cm at intermediate temperatures around 140 °C, where Nafion filled with water is inoperable. Finally the investigation was extended to another solid acid: CsH2PO4. Using the multi-technique approach, these CsH2PO4 composites with nanoparticulate TiO2 or SiO2 were studied and compared to the CsHSO4 composites. Acidity was found to be indicative for the amount of space charge occurring. The results indicate a reduced space charge effect in CsH2PO4-TiO2 composites consistent with the reduced acidity of CsH2PO4 and lower proton accepting capacity of TiO2 compared to SiO2. Using the acidity combined with computer calculations might be a useful way to predict the extent of space charge in future research towards the optimal combination for electrolyte membrane material.","nanoionics; fuel cell electrolytes; space charge; solid acids; proton conduction","en","doctoral thesis","","","","","","","","","Applied Sciences","Applied physics, R3, FAME","","","",""
"uuid:44d57fe5-5ea1-48c2-8b98-d6311d2124b6","http://resolver.tudelft.nl/uuid:44d57fe5-5ea1-48c2-8b98-d6311d2124b6","The role of temperature in nucleation processes","Ter Horst, J.H.; Bedeaux, D.; Kjelstrup, S.","","2011","Heat and mass transfers are coupled processes, also in nucleation. In principle, a nucleating cluster would have a different temperature compared to the surrounding supersaturated old phase because of the heat release involved with attaching molecules to the cluster. In turn a difference in temperature across the cluster surface is a driving force for the mass transfer to and from the cluster. This coupling of forces in nonisothermal nucleation is described using mesoscopic nonequilibrium thermodynamics, emphasizing measurable heat effects. An expression was obtained for the nonisothermal nucleation rate in a one-component system, in the case where a temperature difference exists between a cluster distribution and the condensed phase. The temperature is chosen as a function of the cluster size only, while the temperature of the condensed phase is held constant by a bath. The generally accepted expression for isothermal stationary nucleation is contained as a limiting case of the nonisothermal stationary nucleation rate. The equations for heat and mass transport were solved for stationary nucleation with the given cluster distribution and with the temperature controlled at the boundaries. A factor was defined for these conditions, determined by the heat conductivity of the surrounding phase and the phase transition enthalpy, to predict the deviation between isothermal and nonisothermal nucleation. For the stationary state described, the factor appears to give small deviations, even for primary nucleation of droplets in vapor, making the nonisothermal rate smaller than the isothermal one. The set of equations may lead to larger and different thermal effects under different boundary conditions, however.","enthalpy; heat conduction; heat of transformation; liquid-vapour transformations; mass transfer; nucleation","en","journal article","American Institute of Physics","","","","","","","","Mechanical, Maritime and Materials Engineering","Process and Energy","","","",""
"uuid:c9fc2a31-5c30-48fe-8c30-39121fc59c63","http://resolver.tudelft.nl/uuid:c9fc2a31-5c30-48fe-8c30-39121fc59c63","Photoconductivity of Quantum Dot Films Towards Third-Generation Solar Cells","Talgorn, E.C.V.","Siebbeles, L.D.A. (promotor); Houtepen, A.J. (promotor)","2010","Colloidal semiconductor nanoparticles, also called quantum dots, have unique opto-electronic properties that make them promising candidates for many applications such as solar cells, light–emitting diodes, lasers, or biological imaging. One of the most interesting features is that the bandgap energy can be tuned by changing the particle size. This allows the design of solar cells with optimized absorption of the solar spectrum, resulting in improved power conversion efficiency. Quantum-dot-based opto-electronic devices require photoconductive nanocrystal assemblies, i.e. assemblies in which charge carrier photogeneration and transport are efficient. However, in assemblies of colloidal quantum dots, both the yield for charge carrier photogeneration and the charge mobility are initially low. This is due to the presence of long (1-2 nanometer), insulating molecules that are present at the surface of the dots for particle stabilization and surface passivation. The goal of this thesis was to produce photoconductive films of quantum dots and to understand the mechanisms governing charge generation, transport and decay in those films. Three options to increase the film photoconductivity were investigated in this thesis: capping removal (Chapter 2), capping exchange with short, organic molecules (Chapter 3, 5 and 6), and capping exchange with short, inorganic molecules (Chapter 4). Mobilities greater than 1 cm2/Vs were achieved in films of CdSe and PbSe quantum dots (Chapter 4 and 5), and in some cases, unity quantum yields of charge carrier photogeneration were attained (Chapter 5). Furthermore, charge extraction from quantum dot layers has been demonstrated with encouraging efficiency (Chapter 2). Those results show that quantum dots fulfill the requirements for use as the active material in solar cells.","colloidal nanoparticle; quantum confinement; quantum dot; thin film; solar cell; mobility; photogeneration quantum yield; photoconductivity; Time-Resolved Microwave Conductivity (TRMC)","en","doctoral thesis","","","","","","","","","Applied Sciences","Department of Chemical Engineering","","","",""
"uuid:c32d353f-358c-48ad-a3f2-720656510f4b","http://resolver.tudelft.nl/uuid:c32d353f-358c-48ad-a3f2-720656510f4b","Electrical conductivity and defect chemistry of BaxSr1 - xCoyFe1 - yO3 - dBaxSr1?xCoyFe1?yO3? perovskites","Yáng, Z.; Harvey, A.S.; Infortuna, A.; Schoonman, J.; Gauckler, L.J.","","2010","Bulk BaxSr1 - xCoyFe1 - yO3 - dBaxSr1?xCoyFe1?yO3? compositions (BSCF) were synthesized by the solid-state reaction method. The electrical conductivity of ceramic bars was measured using a dc four-probe method as a function of temperature in air up to 970 °C. All compositions showed thermally activated p-type semi-conductivity up to ~450 °C and then a transition to metal-like conductivity. The small-polaron hopping p-type semi-conductivity depends on the oxygen nonstoichiometry, which increases with increasing temperature. Metal-like conductivity is attributed to the overlap of the transition metal d-electron orbitals with the oxygen p-orbitals. Strontium-rich compositions show higher conductivity. The Co/Fe ratio does not influence much the p-type semi-conduction. Iron-rich compositions revealed more metal-like conduction behavior. The degree of overlap between transition metal d-orbitals and oxygen p-orbitals depends on the Ba/Sr as well as on the Co/Fe ratios.","electrical conductivity; BSCF; mixed ionic and electronic conduction; perovskite; metal-insulator transition; cathode; solid oxide fuel cell; catalysis","en","journal article","Springer","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:507dd58c-a090-4053-8d13-4bcfb719d25b","http://resolver.tudelft.nl/uuid:507dd58c-a090-4053-8d13-4bcfb719d25b","Transport of heat and mass in a two-phase mixture: From a continuous to a discontinuous description","Glavatskiy, K.S.; Bedeaux, D.","","2010","We present a theory that describes the transport properties of the interfacial region with respect to heat and mass transfer. Postulating the local Gibbs relation for a continuous description inside the interfacial region, we derive the description of the Gibbs surface in terms of excess densities and fluxes along the surface. We introduce overall interfacial resistances and conductances as the coefficients in the force-flux relations for the Gibbs surface. We derive relations between the local resistivities for the continuous description inside the interfacial region and the overall resistances of the surface for transport between the two phases for a mixture. It is shown that interfacial resistances depend among other things on the enthalpy profile across the interface. Since this variation is substantial, the coupling between heat and mass flow across the surface is also substantial. In particular, the surface puts up much more resistance to the heat and mass transfer than the homogeneous phases over a distance comparable to the thickness of the surface. This is the case not only for the pure heat conduction and diffusion but also for the cross effects such as thermal diffusion. For the excess fluxes along the surface and the corresponding thermodynamic forces, we derive expressions for excess conductances as integrals over the local conductivities along the surface. We also show that the curvature of the surface affects only the overall resistances for transport across the surface and not the excess conductivities along the surface.","enthalpy; free energy; heat conduction; mass transfer; mixtures; thermal diffusion","en","journal article","American Institute of Physics","","","","","","","","Mechanical, Maritime and Materials Engineering","Process and Energy","","","",""
"uuid:d02df51d-ddbc-43a4-8da0-086a4491cece","http://resolver.tudelft.nl/uuid:d02df51d-ddbc-43a4-8da0-086a4491cece","Photoconductance of conjugated materials for organic electronics","Grzegorczyk, W.J.","Siebbeles, L.D.A. (promotor)","2010","The photogeneration and mobility of charge carriers in organic thin films, including bulk heterojunctions (BHJs), have been studied with the time resolved microwave photo-conductance technique (TRMC). The TRMC technique allows the electrodeless measurement of the photoconductance with nanosecond time resolution. The research focuses on the way in which molecular structure and film morphology affect the optical and the photoconductive properties. Chapter 2 describes the effects of annealing of pDA2T:PCBM BHJ thin films on the nanomorphology and optoelectronic properties. It is shown, that upon annealing extensive phase segregation of the pDA2T and PCBM and crystallization of the polymer domains occur. The segregation leads to a reduced charge separation efficiency and long lifetime of charge carriers. These results show that annealing is an efficient method for manipulating the photophysics of polymer:PCBM BHJs. Chapter 3 presents the relationship of the nanomorphology and the photoconductive properties of several blends based on different poly(thienothiophene) co-polymers and PCBM. Annealing of pDA2T:PCBM and of pBTTT:PCBM at 120 °C (for molecular structures see page 9) leads to phase segregation of the polymer and PCBM. Interestingly, annealing of pBTCT:PCBM at 120 °C and of pBTTT:PCBM at 165 °C results in a multiple bilayer structure, in which PCBM molecules intercalate between polymer chains. The highest photoconductance is obtained for the BHJs exhibiting phase segregation. This is associated with efficient generation of electrons in the PCBM domains. Though in BHJs with a multiple bilayer structure efficient photoluminescence quenching is observed, fast charge carrier recombination results in low photoconductance. Chapter 4 describes studies on thin-film BHJs of poly(3-hexyl thiophene) and soluble oligomers of siloxane substituted with naphthalene diimide (NDIS) moieties, prepared by spin-coating from chloroform (CHCl3) or from ortho-dichlorobenzene (ODCB). CHCl3 derived samples exhibit no phase segregation in TEM images. By contrast, for ODCB derived blends phase segregation occurs with an extent that increases with the molecular weight of the NDIS molecules and the weight content of NDIS. The formation of large NDIS clusters is essential for efficient photogeneration of charges. Chapter 5 addresses the mechanism of photogeneration of charge carriers in P3HT:PCBM bulk heterojunctions. This study has been performed using TRMC and femtosecond transient optical absorption spectroscopy at temperatures ranging from 10 K to 298 K. It is inferred that charge generation does not occur via the Onsager-Braun model. The absence of an effect of temperature on the quantum yield of charges can be due to coupling of the initially hot exciton with excess vibrational energy. The magnitude of the photoconductance is found to be strongly dependent on the film preparation procedure. Chapter 6 reports a study of the relation between the nanomorphology and the mobility of charge carriers in thin films of a liquid crystalline terthiophene derivative. The anisotropy of the optical absorption is much higher than for the mobility. This result can be understood on basis of quantum chemical calculations of electronic couplings for charge transport in different directions.","bulk heterojunction; conjugated polymer; photoconductance; time-resolved microwave conductance; nanomorphology; molecular crystals; organic solar cells; organic field-effect transistors; polythiophenes","en","doctoral thesis","","","","","","","","2010-02-23","Applied Sciences","Chemical Engineering","","","",""
"uuid:6e209248-7741-4743-bf7c-b59d1e1323d8","http://resolver.tudelft.nl/uuid:6e209248-7741-4743-bf7c-b59d1e1323d8","Charging Stations for Urban Settings the design of a product platform for electric vehicle infrastructure in Dutch cities","Hatton, C.E.; Beella, S.K.; Brezet, J.C.; Wijnia, Y.C.","","2009","This paper reflects the essential role of supportive infrastructure in the mass implementation of electric drive vehicle technology. A focus is placed on the development of comprehensive systems that provide efficient and diverse recharging solutions for vehicle drivers. Mass adoption of electric mobility will reflect advances in the vehicles themselves, their infrastructural networks, and their position in the automotive market. Progress in these areas is highly related, and mandates coordinated design efforts. This paper discusses current problem areas, ongoing developments, and future trends in the design and development of charging systems for battery electric vehicles. The application of infrastructures that are simple, familiar, and context-sensitive is essential to promote consumer confidence and thereby enable successful market penetration. Specific requirements and conditions for the design of infrastructure systems for electric mobility are presented.","battery charge; conductive charger; electric vehicle; fast charge,; infrastructure","en","conference paper","European Association of Electric Road Vehicles","","","","","","","","Industrial Design Engineering","Design Engineering","","","",""
"uuid:ddbac1db-a2a3-4320-bfd4-e460ddb2f8fd","http://resolver.tudelft.nl/uuid:ddbac1db-a2a3-4320-bfd4-e460ddb2f8fd","The meaning of competition between social and market rented housing","Lennartz, C.; Haffner, M.E.A.; Oxley, M.J.","","2009","When policy makers claim that rented housing has to become more competitive, there is no consensus on what competition in this context actually means. The same holds true for scientific housing research: Theories that have utilized the economic concept of competition tend to rely on implicit definitions or focus on selected aspects. In particular, one can identify a lack of understanding of competition between the different rented housing tenures. This paper tries to fill this gap as it sheds light on a more detailed meaning of competition in rental housing markets, what it entails, and how it can be assessed. A brief review of competition in economic theory shows that opposing concepts have led to different connotations of the term. Building on the Structure-Conduct-Performance (SCP) paradigm and further theories of competition analysis, the paper intends to develop an innovative framework for analysing competition between social and market rented housing. The presented SCP framework of rented housing illustrates that the competitive relation between social and market housing is reflected in the economic and regulatory environment of the rental market, the behaviour of the landlords and tenants, as well as the economic and social effects of competition.","competition; structure-conduct-performance paradigm; rental housing markets; social housing; rental housing industry","en","conference paper","The Institute of Sociology of the Academy of Sciences of the Czech Republic","","","","","","","","OTB Research Institute","","","","",""
"uuid:2b837601-8d9a-43a6-b4ba-6295a58c0d5d","http://resolver.tudelft.nl/uuid:2b837601-8d9a-43a6-b4ba-6295a58c0d5d","Diameter-dependent conductance of InAs nanowires","Scheffler, M.; Nadj-Perge, S.; Kouwenhoven, L.P.; Borgström, M.T.; Bakkers, E.P.A.M.","","2009","Electrical conductance through InAs nanowires is relevant for electronic applications as well as for fundamental quantum experiments. Here, we employ nominally undoped, slightly tapered InAs nanowires to study the diameter dependence of their conductance. By contacting multiple sections of each wire, we can study the diameter dependence within individual wires without the need to compare different nanowire batches. At room temperature, we find a diameter-independent conductivity for diameters larger than 40 nm, indicative of three-dimensional diffusive transport. For smaller diameters, the resistance increases considerably, in coincidence with a strong suppression of the mobility. From an analysis of the effective charge carrier density, we find indications for a surface accumulation layer.","carrier density; carrier mobility; electrical conductivity; electrical resistivity; III-V semiconductors; indium compounds; nanowires; semiconductor quantum wires","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Kavli Institute of Nanoscience","","","",""
"uuid:778bd5c6-6ab3-4fe3-a6fc-1049f3a3ed1b","http://resolver.tudelft.nl/uuid:778bd5c6-6ab3-4fe3-a6fc-1049f3a3ed1b","An extension of Lauwerier’s Solution for heat flow in saturated porous media","Saeid, S.; Barends, F.B.J.","","2009","One of the crucial topics in this century is sustainable energy. Since the sources of fossil fuels are limited and are going to be exhausted, there is a need to look for sustainable renewable energy. In this respect, the exploitation of geothermal energy from deep hot aquifers becomes opportune. Hence, insight is required in the heat balance of potential aquifer systems. Essential issues are convection, conduction and dispersion. Modeling such processes is affected by numerical errors when using computer models and by the complexity of analytical solutions. This article focuses on Lauwerier’s problem. As an extension, it is suggested that beside convection in the aquifer and conduction to adjacent layers also conduction in an aquifer can be considered in a simple way. For a characteristic situation, a comparison is made with the result of the numerical code COMSOL. This gives new insight in the possible misjudges of heat transport simulations due to numerical effects and in the applicability of models.","geothermal energy; Lauwerier; thermal convection and conduction,; heat transfer","en","conference paper","COMSOL","","","","","","","","Civil Engineering and Geosciences","Geotechnology","","Geo-Engineering","",""
"uuid:969b6c41-fd13-4b93-a5ec-dd4a1adefceb","http://resolver.tudelft.nl/uuid:969b6c41-fd13-4b93-a5ec-dd4a1adefceb","Dielectric behavior and phase transition in perovskite oxide Pb(Fe1/2Nb1/2)1?xTixO3 single crystal","Jia, Y.; Luo, H.; Or, S.W.; Wang, Y.; Chan, H.L.W.","","2009","Perovskite oxide Pb(Fe1/2Nb1/2)0.52Ti0.48O3 crystals, which were grown using a modified Bridgman method, show a high low-frequency dielectric constant response at room temperature. The Curie phase transition occurs at 523 K. The characteristic frequency of the dielectric dispersion versus the inverse of temperature obeys an Arrhenius relation, which shows a thermally activated behavior. The thermal activation energy for relaxation was found to be ? 0.14?eV. The high dielectric permittivity was attributed to oxygen vacancies and conduction via hopping carriers.","crystal growth from melt; ferroelectric Curie temperature; ferroelectric materials; ferroelectric transitions; hopping conduction; iron compounds; lead compounds; niobium compounds; permittivity; vacancies (crystal)","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3e182922-1e50-45a0-9b7b-be2e8669b335","http://resolver.tudelft.nl/uuid:3e182922-1e50-45a0-9b7b-be2e8669b335","Proximity effect in ion-beam-induced deposition of nanopillars","Chen, P.; Salemink, H.W.M.; Alkemade, P.F.A.","","2009","Ion-beam-induced deposition (IBID) is a powerful technique for prototyping three-dimensional nanostructures. To study its capability for this purpose, the authors investigate the proximity effect in IBID of nanopillars. In particular, the changes in shape and dimension of pillars are studied when a second pillar is grown near an existing pillar. On a semiconducting bulk Si and on an insulating Si3N4 membrane the first pillar gets broader, whereas on Si it starts to bend. They attribute the broadening and bending to the additional deposition induced by the particles scattered from the growing second pillar. On Si the second pillar is taller than the first one, while on Si3N4 it is shorter and rougher. This difference points to an important role of the substrate conductivity in the proximity effect. In a conductive environment the changes in the second pillar are mainly caused by a precursor coverage enhancement in the pillar surface. This enhancement is caused by precursor molecules, which are reflected or desorbed from the first pillar. In the case of an insulating environment, the changes in the second pillar are mainly caused by the reduction in the substrate surface charging due to the presence of the first pillar.","bending; electrical conductivity; elemental semiconductors; ion beam assisted deposition; membranes, nanostructured materials; nanotechnology; silicon; silicon compounds,; surface charging; (CH3)3Pt(CPCH3); Pt; Si; Si3N4","en","journal article","American Vacuum Society","","","","","","","","Applied Sciences","QN/Quantum Nanoscience","","","",""
"uuid:0ffb67ab-3f9b-4458-9970-3abc6eaa85af","http://resolver.tudelft.nl/uuid:0ffb67ab-3f9b-4458-9970-3abc6eaa85af","A New Metric for Robustness with Respect to Virus Spread (Work in Progress)","Kooij, R.E.; Schumm, P.; Scoglio, C.; Youssef, M.","","2009","The robustness of a network is depending on the type of attack we are considering. In this paper we focus on the spread of viruses on networks. It is common practice to use the epidemic threshold as a measure for robustness. Because the epidemic threshold is inversely proportional to the largest eigenvalue of the adjacency matrix, it seems easy to compare the robustness of two networks. We will show in this paper that the comparison of the robustness with respect to virus spread for two networks actually depends on the value of the effective spreading rate ?. For this reason we propose a new metric, the viral conductance, which takes into account the complete range of values ? can obtain. In this paper we determine the viral conductance of regular graphs, complete bipartite graphs and a number of realistic networks.","robustness; virus spread; epidemic threshold; viral conductance.","en","conference paper","Springer","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Network Architectures and Services","","","",""
"uuid:0b504793-adcb-4c9b-8ac5-fc20d950b8b4","http://resolver.tudelft.nl/uuid:0b504793-adcb-4c9b-8ac5-fc20d950b8b4","Room-temperature stability of Pt nanogaps formed by self-breaking","Prins, F.; Hayashi, T.; De Vos van Steenwijk, B.J.A.; Gao, B.; Osorio, E.A.; Muraki, K.; Van der Zant, H.S.J.","","2009","We present a method to make Pt nanometer-spaced electrodes that are free of metallic particles and stable at ambient conditions. The nanogaps are fabricated using feedback-controlled electromigration to form few-atom contacts. When performing this procedure at elevated temperatures (>420?K), the Pt contacts undergo self-breaking so that nanometer separated electrode pairs are formed. Once cooled down to lower temperatures, the nanogaps stabilize and can be characterized in detail. We find that current-voltage characteristics can be well fitted to a Simmons model for tunneling and gap-size fluctuations at room temperature determined from these fits stay within 0.6 Å for at least 50 h.","electrical conductivity; electrodes; electromigration; fluctuations; nanofabrication; nanostructured materials; platinum; tunnelling","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Kavli Institute of Nanoscience","","","",""
"uuid:967e3f1d-7caf-4fa7-8f95-42bf1b9245a8","http://resolver.tudelft.nl/uuid:967e3f1d-7caf-4fa7-8f95-42bf1b9245a8","Implementing the Netherlands Code of Conduct for Scientific Practice: A Case Study","Schuurbiers, D.; Osseweijer, P.; Kinderlerer, J.","","2009","Widespread enthusiasm for establishing scientific codes of conduct notwithstanding, the utility of such codes in influencing scientific practice is not self-evident. It largely depends on the implementation phase following their establishment—a phase which often receives little attention. The aim of this paper is to provide recommendations for guiding effective implementation through an assessment of one particular code of conduct in one particular institute. Based on a series of interviews held with researchers at the Department of Biotechnology of Delft University of Technology, this paper evaluates how the Netherlands Code of Conduct for Scientific Practice is received by those it is supposed to govern. While respondents agreed that discussion of the guiding principles of scientific conduct is called for, they did not consider the code as such to be a useful instrument. As a tool for the individual scientific practitioner, the code leaves a number of important questions unanswered in relation to visibility, enforcement, integration with daily practice and the distribution of responsibility. Recommendations are provided on the basis of these questions. There is more at stake than merely holding scientific practitioners to a proper exercise of their duties; implementation of scientific society codes of conduct also concerns the further motives and value commitments that gave rise to their establishment in the first place.","Code of conduct; Science and engineering ethics; Responsible conduct of research; Research integrity; Moral responsibility","en","journal article","Springer","","","","","","","","Applied Sciences","Biotechnology","","","",""
"uuid:050e9fee-09b4-4561-aaea-6da6be44ef75","http://resolver.tudelft.nl/uuid:050e9fee-09b4-4561-aaea-6da6be44ef75","Nonequilibrium thermodynamics of interfaces using classical density functional theory","Johannessen, E.; Gross, J.; Bedeaux, D.","","2008","A vapor-liquid interface introduces resistivities for mass and heat transfer. These resistivities have recently been determined from molecular simulations, as well as theoretically using the van der Waals square gradient model. This model, however, does not allow for direct quantitative comparison to experiment or results from molecular simulations. The classical density functional theory is used here in order to determine the equilibrium profiles of vapor-liquid interfaces. Equilibrium profiles are sufficient in the framework of nonequilibrium thermodynamics for determining the interfacial resistivities. The interfacial resistivities for heat transfer, for mass transfer, and for the coupling of heat and mass transfer can all be related to only one local thermal resistivity. This is done with integral relations for the interfacial resistivities. All interfacial resistivities can be consistently described in their temperature behavior with good accuracy.","density functional theory; heat transfer; interface phenomena; liquid theory; mass transfer; molecular dynamics method; nonequilibrium thermodynamics; thermal conductivity","en","journal article","American Institute of Physics","","","","","","","","Mechanical, Maritime and Materials Engineering","Process and Energy","","","",""
"uuid:327148a5-afea-47d5-88b4-ebfdde53f602","http://resolver.tudelft.nl/uuid:327148a5-afea-47d5-88b4-ebfdde53f602","An experimental study on the molecular organization and exciton diffusion in a bilayer of a porphyrin and poly(3-hexylthiophene)","Huijser, A.; Savenije, T.J.; Shalav, A.; Siebbeles, L.D.A.","","2008","The exciton root-mean-square displacement (?D) in regioregular poly(3-hexylthiophene) (P3HT) deposited onto meso-tetrakis (n-methyl-4-pyridyl) porphyrin tetrachloride (H2TMPyP) has been determined from the photovoltaic response of a device based on these materials in a bilayer configuration. Excitons formed on illumination that reach the interface between H2TMPyP and P3HT can undergo interfacial charge separation by electron injection into the H2TMPyP and hole injection into the P3HT. The incident photon to current efficiency (IPCE) exceeds 20% over a broad wavelength regime. The theoretical analysis of the IPCE values gives a value for ?D in H2TMPyP that amounts to 14 nm, while for P3HT a value of 18 nm is obtained. The latter value exceeds literature values reported for P3HT by almost a factor of 3. X-ray diffraction analysis shows that in the studied bilayer the P3HT backbones are aligned parallel to the interface with H2TMPyP. In contrast, in the case of P3HT deposited onto TiO2, for which ?D has been reported to equal only 7 nm, hardly any organization of the P3HT backbones is observed. The excitonic coupling between P3HT backbones deposited onto H2TMPyP is as high as 125?cm?1, a factor of 3 larger than the excitonic coupling between the disordered P3HT backbones that amounts to 47?cm?1. The difference illustrates the importance of controlling the molecular organization for the realization of efficient energy transfer in organic optoelectronics.","charge injection; conducting polymers; diffusion; excitons; photovoltaic effects; polymer films; X-ray diffraction","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","DelftChemTech","","","",""
"uuid:33325103-1c81-4ad4-a477-9d6f58e096bb","http://resolver.tudelft.nl/uuid:33325103-1c81-4ad4-a477-9d6f58e096bb","The effect of a neighboring metal layer on the high-frequency characteristics of a thin magnetic stripe","Vroubel, M.; Rejaei, B.","","2008","The spin-wave spectrum of a ferromagnetic stripe placed above a metallic layer with finite conductivity is studied by using the magnetostatic Green’s function formalism. It is shown that the frequency and linewidth of the resonances are uniquely determined by complex, mode-dependent demagnetization factors. The formalism developed is used to analyze the resonance characteristics of the magnetic stripe as a function of its width and separation from the metallic layer.","demagnetisation; electrical conductivity; ferromagnetic materials; ferromagnetic resonance; Green's function methods; magnetic thin films","en","journal article","American Institute of Physics","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Delft Institute of Microelectronics and Submicron Technology","","","",""
"uuid:e3b442bb-5cda-4dbb-b2ef-f0d8eef4f543","http://resolver.tudelft.nl/uuid:e3b442bb-5cda-4dbb-b2ef-f0d8eef4f543","Model prediction of subendocardial perfusion of the coronary circulation in the presence of an epicardial coronary artery stenosis","Van den Wijngaard, J.P.H.M.; Kolyva, C.; Siebes, M.; Dankelman, J.; Van Gemert, M.J.C.; Piek, J.J.; Spaan, J.A.E.","","2008","The subendocardium is most vulnerable to ischemia, which is ameliorated by relaxation during diastole and increased coronary pressure. Recent clinical techniques permit the measuring of subendocardial perfusion and it is therefore important to gain insight into how measurements depend on perfusion conditions of the heart. Using data from microsphere experiments a layered model of the myocardial wall was developed. Myocardial perfusion distribution during hyperemia was predicted for different degrees of coronary stenosis and at different levels of Diastolic Time Fraction (DTF). At the reference DTF, perfusion was rather evenly distributed over the layers and the effect of the stenosis was homogenous. However, at shorter or longer DTF, the subendocardium was the first or last to suffer from shortage of perfusion. It is therefore concluded that the possible occurrence of subendocardial ischemia at exercise is underestimated when heart rate is increased and DTF is lower.","Coronary reserve; Steal; Heart model; Regional conductance; Diastolic time fraction","en","journal article","Springer","","","","","","","","Applied Sciences","Department of BioMechanical Engineering","","","",""
"uuid:c64d84d8-6552-4d3c-9c02-1d511c689c43","http://resolver.tudelft.nl/uuid:c64d84d8-6552-4d3c-9c02-1d511c689c43","Scaling-Up Eutectic Freeze Crystallization","Genceli, F.E.","Witkamp, G.J. (promotor)","2008","A novel crystallization technology, Eutectic Freeze Crystallization (EFC) has been investigated and further developed in this thesis work. EFC operates around the eutectic temperature and composition of aqueous solutions and can be used for recovery of (valuable) dissolved salts (and/or or acids) and water from a wide variety of aqueous process streams. Using EFC, processes producing large quantities of saline solutions could be carried out in an ecologically and economically attractive way. An introduction and a brief summary of earlier work are given in Chapter 1. The experimental study on pilot scale Cooled Disc Column Crystallizer (CDCC-2) designed for continuous EFC operation is presented in Chapter 2. CDCC-2 was tested for an industrial MgSO4 stream and evaluated in terms of heat transfer, ice and salt sizes, production and growth rates. Application of conductivity and refractive index measurement techniques for inline concentration and supersaturation measurements of MgSO4 solution was studied in Chapter 3. Chapter 4 presents the CDCC-3 and Skid Mounted Unit, designed and constructed for 130 ton/year MgSO4.7H2O and water production capacities. MgSO4 salt crystal structure at eutectic conditions was studied and reported in Chapter 5. The MgSO4 crystal hydrate formed below approximately 0 oC was proven to be MgSO4.11H2O instead of the common reported MgSO4.12H2O. Crystal structure analysis and the molecular arrangement of these crystals were determined using single crystal X-ray diffraction. Raman spectroscopy was used for characterizing MgSO4.11H2O and for comparing the vibrational spectra with MgSO4.7H2O. Thermo gravimetric analysis confirmed the stochiometry of MgSO4.11H2O. Additionally the Miller indices of the major faces of MgSO4.11H2O crystals were defined. Chapter 6 covers the discovery of the natural occurrence of the MgSO4.11H2O new mineral -Meridianiite- as salt inclusions in sea ice from Saroma Lake-Japan and in Antarctic ice. In Chapter 7 nucleation and crystal growth of MgSO4 aqueous solution on a cooled surface were studied theoretically and experimentally. Coupled heat and mass flux equations from non-equilibrium thermodynamics (Onsager theory with reciprocal relations) were defined for crystal growth and the temperature jump at the interface of the growing crystal. Chapter 8 aims to describe the Cyclic Innovation Model (CIM) and to set a path for commercialization of the EFC technology.","eutectic freeze crystallization; magnesium sulfate; mgso4.11h2o; meridianiite; inline supersaturation determination; inline conductivity measurement; inline refractive index measurement; epsomite; xrd; x-ray diffraction; negative crystal; micro raman spectroscopy; antarctic ice; saroma lake; sea ice; mineral; coupled heat and mass transfer; non-equilibrium thermodynamics; onsager relations; irreversible thermodynamics; crystal growth on a cold surface; cyclic innovation model; cim; cooled disc column crystallizer; cdcc; interface; skid mounted unit; scale-up; crystallization; waste water treatment; aqueous process stream treatment; thermogravimetric analysis; tga","en","doctoral thesis","","","","","","","","","Mechanical Maritime and Materials Engineering","","","","",""
"uuid:dbc73130-f88e-4533-98eb-ccd8342e92db","http://resolver.tudelft.nl/uuid:dbc73130-f88e-4533-98eb-ccd8342e92db","A high-performance interface for grounded conductivity sensors","Li, X.; Meijer, G.C.M.","","2008","","sensor interface; oscillators; grounded conductance measurement","en","journal article","IOP","","","","","","","","Technology, Policy and Management","","","","",""
"uuid:4d96d9cd-2999-4e24-b78a-c260df7c0107","http://resolver.tudelft.nl/uuid:4d96d9cd-2999-4e24-b78a-c260df7c0107","Nonreciprocal spin wave spectroscopy of thin Ni–Fe stripes","Khalili Amiri, P.K.; Rejaei, B.; Vroubel, M.; Zhuang, Y.","","2007","The authors report on the observation of nonreciprocal spin wave propagation in a thin ( ? 200?nm) patterned Ni–Fe stripe. The spin wave transmission spectrum is measured using a pair of microstrip lines as antennas. The nonreciprocity of surface wave dispersion brought about by an adjacent aluminum ground leads to a nonreciprocal coupling of the antennas. The effects of Ni–Fe film conductivity, thickness, and reflections caused by the lateral confinement of the magnetic stripe are discussed. The nonreciprocity observed in this structure can potentially be used to realize nonreciprocal microwave devices on silicon.","aluminium; antennas; electrical conductivity; iron alloys; magnetic thin films; metallic thin films; nickel alloys; spin waves","en","journal article","American Institute of Physics","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Microelectronics & Computer Engineering","","","",""
"uuid:954f2f28-094c-45ba-b62a-554756ff45d6","http://resolver.tudelft.nl/uuid:954f2f28-094c-45ba-b62a-554756ff45d6","Bias-dependent contact resistance in rubrene single-crystal field-effect transistors","Molinari, A.; Gutiérrez, I.; Hulea, I.N.; Russo, S.; Morpurgo, A.F.","","2007","The authors report a systematic study of the bias-dependent contact resistance in rubrene single-crystal field-effect transistors with Ni, Co, Cu, Au, and Pt electrodes. They show that the reproducibility in the values of contact resistance strongly depends on the metal, ranging from a factor of 2 for Ni to more than three orders of magnitude for Au. Surprisingly, field-effect transistors with Ni, Co, and Cu contacts exhibit an unexpected reproducibility of the bias-dependent differential conductance of the contacts once this has been normalized to the value measured at zero bias. This reproducibility may enable the study of microscopic carrier injection processes into organic semiconductors.","nickel; cobalt; copper; gold; platinum; organic semiconductors; field effect transistors; electrodes; contact resistance; electrical conductivity","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Kavli Institute of Nanoscience","","","",""
"uuid:add35428-fb1e-419d-968f-c70885300c07","http://resolver.tudelft.nl/uuid:add35428-fb1e-419d-968f-c70885300c07","Thermal and electrical properties of porphyrin derivatives and their relevance for molecule interferometry","Deachapunya, S.; Stefanov, A.; Berninger, M.; Ulbricht, H.; Reiger, E.; Doltsinis, N.L.; Arndt, M.","","2007","The authors present new measurements of thermal and electrical properties for two porphyrin derivatives. They determine their sublimation enthalpy from the temperature dependence of the effusive beam intensity. The authors study H2TPP and Fe(TPP)Cl in matter-wave interferometry. Both molecules have nearly equal de Broglie wavelengths but different internal characteristics: only Fe(TPP)Cl exhibits an electric dipole moment of about 2.7?D and the authors discuss its influence on the molecular interference pattern. The authors add an external electric force field to the interferometer and use it to measure the scalar polarizability. They compare their experimental values ?(H2TPP) = 105±4±6?Å3 and ?(Fe(TPP)Cl) = 102±9±6?Å3 to ab initio calculations and they discuss the influence of thermal excitations on the polarizability.","organic compounds; iron compounds; thermal conductivity; electrical conductivity; enthalpy; electric moments; polarisability; sublimation","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Kavli Institute of Nanoscience","","","",""
"uuid:cf3d25a8-0dd0-41a5-b51e-7fc02ed3aaa3","http://resolver.tudelft.nl/uuid:cf3d25a8-0dd0-41a5-b51e-7fc02ed3aaa3","Discotic liquid crystals: From dynamics to conductivity","Kruglova, O.V.","Kearley, G.J. (promotor); Mulder, F.M. (promotor)","2007","The dynamics and conductivity of the discotic liquid-crystal, hexakis(n-hexylox) triphenylene (HAT6), and charge-transfer complex that it forms with 2,4,7trinitro-9-fluorenone (TNF) are studied using quasielastic neutron-scattering (QENS) and Pulse-Radiolysis Time resolved Conductivity. These two techniques measure the molecular dynamics and conductivity decay, respectively, are interpreted in terms of a single model for the relaxation kinetics for a correlating environment. Use of a single model supposes that the molecular and charge dynamics are described by the same kinetic equation, which allows description of the system behaviour in space and time when combined with fractional diffusion equation. This supposition is substantiated by relating the two systems through the dispersion parameter, I2. This enables the range of the charge mobility to be linked to the length-scale of the molecular motion from which a coupling parameter is derived. The conductivity and molecular dynamics of HAT6 and HAT6-TNF are analysed in terms of the dynamical and coupling parameters. The thermal motion of a short column of HAT6 is simulated by a molecular dynamics simulation in order to provide the correct distribution of distorted molecular units, including the effects of the alkoxy tails. Ab-initio calculations are then used to determine the electronic structure of the distorted triphenylene cores and the time dependence of the interaction between these. A compact model for the vibrational dynamics of HAT6 is derived from the combined use of inelastic neutron scattering spectroscopy and first-principles calculations. It reproduces the essential features of the vibrational dynamics and electronic structure on the aromatic core of HAT6.","liquid crystals; neutron scattering; dynamics; conductivity","en","doctoral thesis","IOS Press","","","","","","","","Applied Sciences","","","","",""
"uuid:552dd9da-1f1c-4667-b10e-c4e1aab3aafc","http://resolver.tudelft.nl/uuid:552dd9da-1f1c-4667-b10e-c4e1aab3aafc","Luminescence quenching by photoionization and electron transport in a LaAlO3:Ce3+ crystal","Van der Kolk, E.; De Haas, J.T.M.; Bos, A.J.J.; Van Eijk, C.W.E.; Dorenbos, P.","","2007","A combined photoconductivity, absorption, and thermoluminescence study was performed to understand the absence of luminescence from Ce3+ in LaAlO3:Ce3+. It is demonstrated that the absence of luminescence is the result of Ce3+ ionization from the 5d excited states, which are all located in the conduction band. Ce3+ ionization is accompanied by the formation of several broad absorption and photoconductivity bands, which are assigned to electron traps. A time and temperature dependent optical investigation of these traps reveals the conditions under which electrons are transferred from Ce3+ to traps and vice versa, from traps back to Ce4+. The observed difference in energy needed to thermally or optically release electrons from traps is qualitatively explained in terms of the location of the ground and excited states of the electron traps with respect to the conduction band.","lanthanum compounds; cerium; photoconductivity; thermoluminescence; impurity absorption spectra; electron traps; conduction bands; photoionisation","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Radiation, Radionuclides and Reactors","","","",""
"uuid:0f1798b4-d559-4c69-a962-f9282ea52e41","http://resolver.tudelft.nl/uuid:0f1798b4-d559-4c69-a962-f9282ea52e41","Subthreshold channels at the edges of nanoscale triple-gate silicon transistors","Sellier, H.; Lansbergen, G.P.; Caro, J.; Rogge, S.; Collaert, N.; Ferain, I.; Jurczak, M.; Biesemans, S.","","2007","The authors investigate the subthreshold behavior of triple-gate silicon field-effect transistors by low-temperature transport experiments. These three-dimensional nanoscale devices consist of a lithographically defined silicon nanowire surrounded by a gate with an active region as small as a few tens of nanometers down to 50×60×35?nm3. Conductance versus gate voltage shows Coulomb blockade oscillations with a large charging energy due to the formation of a small potential well below the gate. According to dependencies on device geometry and thermionic current analyses, the authors conclude that subthreshold channels, a few nanometers wide, appear at the nanowire edges, hence providing an experimental evidence for the corner effect.","silicon; elemental semiconductors; insulated gate field effect transistors; electrical conductivity; Coulomb blockade","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Kavli Institute of Nanoscience","","","",""
"uuid:1cb28f63-d54e-46d0-bd49-d7d87e87083b","http://resolver.tudelft.nl/uuid:1cb28f63-d54e-46d0-bd49-d7d87e87083b","Carbon nanotube-based superconducting and ferromagnetic hybrid systems","Man, H.T.","Klapwijk, T.M. (promotor); Morpurgo, A.F. (promotor)","2006","Carbon Nanotubes are molecules with exceptional physical properties that are most useful for applications in the growing field of nanotechnology. In addition, because of its special electrical properties, they are extremely useful for experiments on the fundamental properties of one-dimensional electronic systems. This thesis describes a series of experiments and a short numerical study aimed at a further understanding of the low-temperature electrical transport of single-walled carbon nanotubes. In this work we perform the first experimental study on the effect of quantum interference in single-wall nanotubes in the presence of disorder, leading to the observation of a weak localization effect and conductance fluctuations. Shifting the focus to systems with superconducting or ferromagnetic contacts, we first propose a phenomenological model to describe the experimental results from a former study with superconducting contacts. We also contact single-wall nanotubes with the large-gap superconductor NbTiN to study the rich interplay between Coulomb blockade, level quantization and superconductivity. And finally, the experimental study of nanotubes with highly transparent ferromagnetic contacts shows that the spin-dependent magnetoresistance is due to quantum interference.","carbon nanotube; weak localization; universal conductance fluctuation; andreev reflection; electron-electron interaction; superconductor; spin transport","en","doctoral thesis","","","","","","","","","Applied Sciences","","","","",""
"uuid:4200db54-ceff-4003-aa76-8525f3b43bed","http://resolver.tudelft.nl/uuid:4200db54-ceff-4003-aa76-8525f3b43bed","Location of lanthanide impurity levels in the III-V semiconductor GaN","Dorenbos, P.; Van der Kolk, E.","","2006","Knowledge from lanthanide spectroscopy on wide band gap (6–10?eV) inorganic compounds is used to understand and predict optical and electronic properties of the lanthanides in the III-V semiconductor GaN. For the first time the location of the 4fn ground state energy of each divalent and trivalent lanthanide ion relative to the valence and conduction bands in GaN is presented. The authors will demonstrate that the quantum efficiency of luminescence from Pr3+, Eu3+, Tb3+, and Yb3+ depends on the location of the lanthanide levels. Level location also controls electron acceptor and electron donor properties of lanthanide ions.","gallium compounds; III-V semiconductors; wide band gap semiconductors; impurity states; ground states; valence bands; conduction bands; photoluminescence; praseodymium; europium; terbium; ytterbium","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Radiation, Radionuclides and Reactors","","","",""
"uuid:6ae01098-ac49-4dcc-9c4f-381f33f0cd96","http://resolver.tudelft.nl/uuid:6ae01098-ac49-4dcc-9c4f-381f33f0cd96","Charge deep-level transient spectroscopy study of high-energy-electron-beam-irradiated hydrogenated amorphous silicon","Klaver, A.; Nádady, V.; Zeman, M.; Swaaiij, R.A.C.M.M.","","2006","We present a study of changes in the defect density of states in hydrogenated amorphous silicon (a-Si:H) due to high-energy electron irradiation using charged deep-level transient spectroscopy. It was found that defect states near the conduction band were removed, while in other band gap regions the defect-state density increased. A similar trend is observed for a-Si:H which has been subjected to light soaking, but in that case the majority of defect states are created around midgap, whereas with electron-beam degradation more defect states are created near the valence-band tail.","silicon; hydrogen,; elemental semiconductors; amorphous semiconductors; deep level transient spectroscopy; electron beam effects; defect states; conduction bands; energy gap; valence bands","en","journal article","American Institute of Physics","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Electrical Sustainable Energy","","","",""
"uuid:4cec8e53-14ce-40b8-bd4a-e89a8cd7f7cb","http://resolver.tudelft.nl/uuid:4cec8e53-14ce-40b8-bd4a-e89a8cd7f7cb","Electrical transport measurements on self-assembled organic molecular wires","Durkut, M.; Mas-Torrent, M.; Hadley, P.; Jonkheijm, P.; Schenning, A.P.H.J.; Meijer, E.W.; George, S.; Ajayaghosh, A.","","2006","The electrical properties of supermolecular assemblies of oligo(p-phenylene vinylene) were studied. These materials self-assemble into well-defined cylindrical structures in solution with lengths in the range of 100?nm–10??m and diameters between 5 and 200?nm. Atomic force microscopy showed that by adjusting the concentration, either individual molecular wires or a dense film could be deposited. The molecular wires showed poor electrical conduction. Several tests were performed that show that it was the molecular wires themselves, not the contacts, that limit the conductivity.","organic semiconductors; electrical conductivity; self-assembly; atomic force microscopy; molecular electronics; wires (electric)","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Kavli Institute of Nanoscience","","","",""
"uuid:9370a88b-dbbc-4e65-bc2d-7e1042b7f21a","http://resolver.tudelft.nl/uuid:9370a88b-dbbc-4e65-bc2d-7e1042b7f21a","Deep-level transient spectroscopy of TiO2/CuInS2 heterojunctions","Nanu, M.; Boulch, F.; Schoonman, J.; Goossens, A.","","2005","Deep-level transient spectroscopy (DLTS) has been used to measure the concentration and energy position of deep electronic states in CuInS2. Flat TiO2?CuInS2 heterojunctions as well as TiO2-CuInS2 nanocomposites have been investigated. Subband-gap electronic states in CuInS2 films are mostly due to antisite point defects and vacancies. Substitution of indium with copper, CuInII, leads to an acceptor state 0.15 eV above the valence band, while copper vacancies, VCuI, are acceptor states at 0.1 eV. Furthermore, indium on a copper position, InCu?, yields a donor state at 0.07 eV below the conduction band, while sulphur vacancies are donor states at 0.0 = eV. With DLTS, these states are indeed found. For flat configurations, VCuI are the dominant acceptors with a concentration of 1.83×1017?cm?3. In contrast for nanocomposites CuInII are the dominant acceptors having a concentration of 6.7×1017?cm?3. We conclude that the concentration of antisite defects in nanocomposite CuInS2 is significantly higher than that in flat films of CuInS2.","deep level transient spectroscopy; titanium compounds; copper compounds; indium compounds; ternary semiconductors; semiconductor heterojunctions; nanocomposites; vacancies (crystal); impurity states; valence bands; conduction bands","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","DelftChemTech","","","",""
"uuid:6bd0ab46-e810-49d5-8897-109a4d3a890e","http://resolver.tudelft.nl/uuid:6bd0ab46-e810-49d5-8897-109a4d3a890e","Polypyrrole electrochemistry: Environmentally friendly corrosion protection of steel: (im)possibilities","Hamer, W.J.","De Wit, J.H.W. (promotor); Van der Linde, R. (promotor)","2005","Chromate compounds have been widely used to improve the corrosion protection of galvanised steel and aluminium objects in the past decades. The hexavalent chromium in chromate enhances the adherence of coatings to galvanised steel and aluminium. Additionally, if the passive layers on these materials should become damaged, hexavalent chromium supports the repair of these layers to restore passivity. The carcinogenic nature of hexavalent chromium has been well-known for many years, but it is still used because no viable alternatives are available. The mechanism of corrosion protection by hexavalent chromium is heavily researched, as is the development of less toxic alternative corrosion protective treatments. In the near future, the use of chromate will be restricted or even completely banned (chapter 1). As the improvements in corrosion resistance provided by chromate are still necessary, alternative treatments are called for. Solutions are being sought in, among others, the following areas: molybdate and cerate treatments, trivalent chromium compounds, silane coatings and conducting polymers. This thesis exclusively deals with conducting polymer coatings on steel substrates. In chapter 2 some background information on conducting polymers is provided, including the serendipitous discovery of the first of the conducting polymers (polyacetylene) in the 1970s. Chapter 3 provides a theoretical treatment on semiconductor electrochemistry, which is a relevant topic as conducting polymers may possess semiconductive properties. The main difference between semiconducting and metal electrodes is the presence of a space charge layer in the former, which may dominate the electrochemical behaviour of the electrode under certain circumstances. The potential range in which semiconductive properties dominate this behaviour ismarked by the flatbandpotential. Chapter 4 deals with the production of conducting polypyrrole layers on steel substrates by electrochemical deposition. The method used is wellknown from literature, yet the steps involved in the reaction mechanism have not all been explained. By stressing that the desorption of ferrous oxalate must occur prior to the deposition of polypyrrole, this thesis contributes to the clarification of the reaction mechanism of polypyrrole electrodeposition. Chapter 4 also describes experiments to determine the polypyrrole layer thickness as a function of deposition time. Similar experiments have been performed to determine the influence of large (polymeric) anions on the obtained layer thickness. The chapter concludes with an analysis of semiconducting properties of polypyrrole layers on steel substrates. From this analysis, a flatband potential of approx. -400 mVNHE is determined. As this potential marks the upper boundary of the range in which the space charge capacity influences the electrochemical behaviour of the electrode, it can be assumed that such influence is not observed in the potential range relevant to corrosion protection (-400 to +400 mVNHE). The electrochemistry of polypyrrole layers on steel is described in chapter 5. An overview of several possible mechanisms for corrosion protection of steel by conducting polymers is given. From this overview, it is observed that the mechanism most accepted in literature (anodic protection) requires some refinement. The Schottky barrier model proposed by Jain et al. is scarcely mentioned in literature, but section 5.2 shows that a combination of this model with the anodic protection model yields an interesting perspective. The remainder of chapter 5 deals with experimental results obtained by open circuit potential monitoring and electrochemical impedance spectroscopy. Both single and dual layer configurations produced according to the description in chapter 4 were used to examine the influence of the polymeric anions in the dual layer configuration. It is shown that the presence of large anions in the dual layer systems effectively blocks the exchange of ions with the electrolyte solutions. In immersion experiments the time to failure of single layer systems is exceeded significantly by comparable dual layer samples, especially in chloriderich solutions. It is shown that in dual layer samples, the low frequency transport of charges is effectively blocked by the presence of large (polymeric) anions in the layer. In addition to this results, the impedance experiments reported in chapter 5 show that the development of a corrosion process underneath the coating can be detected before the coating physically fails. In other words, the developing corrosion process can be monitored well before it becomes exposed to the electrolyte solution. To date, this has not been reported in literature. Chapter 6 deals with the commercial development of a corrosion protective coating system based on conducting polymers. The poor processability of conducting polymers is circumvented by the used of core/shell latex systems. In such systems, on attempts to combine the processability of the soft core material with the functional properties (e.g. conduction) of the shell material. After several iterations to optimise the system, coatings were produced with satisfactory coating qualities. The experiments described in chapter 6 show that the corrosion protective properties of these coatings were mediocre at best, although many of them could protect the substrates until a defect in the coating occurred. The final chapter of this thesis summarises the conclusions drawn in the preceding chapters. In addition, the general discussion in this chapter links together some of the preceding chapters.","corrosion; conducting polymer; polypyrrole; electrochemistry; corrosion protection","en","doctoral thesis","","","","","","","","","Applied Sciences","","","","",""
"uuid:6dfd4bae-d966-4ddd-ace9-74ccf42504de","http://resolver.tudelft.nl/uuid:6dfd4bae-d966-4ddd-ace9-74ccf42504de","Mechanism of Persistent Luminescence in Eu2+ and Dy3+ Codoped Aluminate and Silicate Compounds","Dorenbos, P.","","2005","A mechanism of persistent luminescence that was proposed in 1996 for SrAl2O4:Eu2+;Dy3+ has been widely adopted to explain afterglow in many Eu2+ and Dy3+ codoped aluminates and silicates. The mechanism involves the thermally activated release of a hole from Eu2+ in its excited 5d state to the valence band which is subsequently trapped by Dy3+. In this work the location of the lanthanide energy levels relative to the valence and conduction band of various compounds is presented. It is shown that the mechanism of persistent luminescence cannot be correct. An alternative model that involves the ionization of the 5d electron to conduction band states and subsequent trapping by Dy3+ is proposed. The level schemes are consistent, both qualitatively and quantitatively, with many observations regarding persistent luminescence. They also provide insight into the mechanism of thermal quenching of Eu2+ 5d-4f emission.","europium; dysprosium; silicon compounds; calcium compounds; gallium compounds; strontium compounds; electroluminescence; phosphors; afterglows; excited states; valence bands; conduction bands; ionisation; quenching (thermal)","en","journal article","The Electrochemical Society","","","","","","","","Applied Sciences","RRR/Radiation, Radionuclides and Reactors","","","",""
"uuid:816260ff-c1ef-4f54-85ec-07d324129e73","http://resolver.tudelft.nl/uuid:816260ff-c1ef-4f54-85ec-07d324129e73","Photoinduced charge separation in dye-sensitized films of smooth and nanocrystalline TiO2","Kroeze, J.E.","Siebbeles, L.D.A. (promotor)","2004","","Photovoltaics; TiO2; microwave conductivity; solar cells; porphyrins","en","doctoral thesis","Delft University Press","","","","","","","","Applied Sciences","","","","",""
"uuid:8162b114-b6d6-4d0d-b325-4c3321763e38","http://resolver.tudelft.nl/uuid:8162b114-b6d6-4d0d-b325-4c3321763e38","Single-Electron and Molecular Devices","Lientschnig, G.","Mooij, J.E. (promotor)","2003","The exponential downscaling of (sub-) microelectronic devices known as Mooreâs law will continue in all likelihood for the next two decades. Transistors with lengths below 10 nm have already been successfully demonstrated. However, once the length of transistors will have been reduced to only a couple of nanometers, present-day CMOS technology and its future derivatives will hit a fundamental limit. Such transistors will not exhibit gain anymore, gain being a fundamental requirement for logic circuits. Novel devices using quantum-mechanical effects might lead to a new method of performing classical computation, though. Two types of devices, single-electron transistors (SETâs) and devices with active regions formed by only one or a few organic molecules were investigated in this thesis. Single-electron transistors can be switched on and off when just one single electron is added to the gate. Even though we arrived at the conclusion that SETâs are not likely to be able to compete with conventional CMOS technology, we argue that hybrid circuits of SETâs and CMOS transistors are of potentially great value for sensing and memory applications. Computational tools to simulate such circuits have been developed. The fabrication of devices in which one single molecule is contacted by two electrodes to measure its conductance, has been a very active research area in the past years. Little is known about the intramolecular conduction mechanism of organic molecules. Experimentally it has been very difficult to contact them and place a gate electrode nearby so that the conductance can be measured as a function of gate voltage. We measured the gate-dependent conductance of ~8 nm long molecules, and there is considerable evidence that we even succeeded in measuring 1,4-benzenedithiol, which has a length of just 0.7 nm. Atypical coherent conductance phenomena could be observed for this device, and if our claim is right, this is the smallest molecule for which a gate-dependent current measurement has been conducted so far.","single-electron tunneling networks; hybrid set-fet simulations; charge traps; aluminum oxide; self-assembled monolayers; conduction through oligomers and organic molecules","en","doctoral thesis","","","","","","","","","Applied Sciences","","","","",""
"uuid:50f0a2fb-4c78-408a-8423-f5ffa3f14893","http://resolver.tudelft.nl/uuid:50f0a2fb-4c78-408a-8423-f5ffa3f14893","Temperature dependent spectroscopic studies of the electron delocalization dynamics of excited Ce ions in the wide band gap insulator, Lu2SiO5","Van der Kolk, E.; Basun, S.A.; Imbusch, G.F.; Yen, W.M.","","2003","Electron delocalization processes of optically excited states of Ce3+ impurities in Lu2SiO5 were investigated by means of a temperature and spectrally resolved photoconductivity study. By monitoring separately the strength of the photocurrent resulting from excitation into each of the Ce3+?5d absorption bands, over a broad temperature region, three different delocalization processes, namely direct photoionization, thermal ionization, and tunneling, have been identified. The relative probabilities and temperature dependencies of each of these processes are discussed. The observed exponential temperature increase in the photocurrent, which spans six orders of magnitude, allows for the exact placement of the lowest energy 5d levels of the Ce3+ ions within the band gap. For Lu2SiO5:Ce3+, the lowest 5d state is determined to be 0.45 eV below the conduction band edge.","lutetium compounds; cerium; impurity states; excited states; photoconductivity; photoionisation; tunnelling; conduction bands; energy gap","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Radiation, Radionuclides and Reactors","","","",""
"uuid:33370034-7868-477d-ac92-057efdcc375e","http://resolver.tudelft.nl/uuid:33370034-7868-477d-ac92-057efdcc375e","Conductivity detection for application in capillary electrophoresis microchips","Laugere, F.P.J.","French, P.J. (promotor); Vellekoop, M.J. (promotor)","2003","","Miniaturized total analysis system; capillary electrophoresis; conductivity detection","en","doctoral thesis","","","","","","","","","Electrical Engineering, Mathematics and Computer Science","","","","",""
"uuid:e5f01f17-adac-4b7a-bce1-d85581f592b7","http://resolver.tudelft.nl/uuid:e5f01f17-adac-4b7a-bce1-d85581f592b7","Electrical properties, texture, and microstructure of vicinal YBa2Cu3O7?? thin films","Pedarnig, J.D.; Rössler, R.; Delamare, M.P.; Lang, W.; Bäuerle, D.; Köhler, A.; Zandbergen, H.W.","","2002","Vicinal YBa2Cu3O7?? (YBCO) thin films of thickness h = 20–480?nm are grown by pulsed-laser deposition on 10° miscut (001) SrTiO3 substrates. The anisotropic resistivities, c-axis texture, and critical temperature drastically depend on the thickness of vicinal films. High-resolution electron microscopy reveals a defect microstructure with strong bending of the YBCO lattice near the SrTiO3 interface and improved film microstructure at larger distances to the substrate. The required layer thickness for microstructure relaxation and increase of electrical conductivity are significantly larger than the critical thickness of c-axis oriented YBCO films.","yttrium compounds; barium compounds; high-temperature superconductors; superconducting thin films; electrical conductivity; texture; pulsed laser deposition; superconducting transition temperature; electron microscopy","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","Kavli Institute of Nanoscience","","","",""
"uuid:365b26b4-b02c-4db6-8e23-a0b220a52352","http://resolver.tudelft.nl/uuid:365b26b4-b02c-4db6-8e23-a0b220a52352","Nanofabrication of electrodes with sub-5 nm spacing for transport experiments on single molecules and metal clusters","Bezryadin, A.; Dekker, C.","","1997","","5 nm; A6146 Structure of solid clusters, nanoparticles, and nanostructured materials; A8115G Vacuum deposition; AuPd; C; carbon; carbon nanotube; carbon nanotubes; conducting nanoparticle; conjugated polymer; direct visual control; electrical transport; electrodes; electron beam deposition; electron microscope; electrostatic trapping; free standing carbon electrode; INSPEC; metal cluster; metal clusters; metal film coating; nanoelectrodes; nanofabrication; nanotechnology; nanotubes; nanowire; Pd; single molecule; single molecules; transport; transport properties; trapping","en","journal article","AIP for American Vacuum Soc","","","","","","","","","","","","",""
"uuid:dd15ceb0-4b02-4336-97bd-4de9968710a4","http://resolver.tudelft.nl/uuid:dd15ceb0-4b02-4336-97bd-4de9968710a4","Deposition and atomic force microscopy of individual phthalocyanine polymers between nanofabricated electrodes","Tans, S.J.; Geerligs, L.J.; Dekker, C.; Wu, J.; Wegner, G.","","1997","","1 nm; A6140K Structure of polymers, elastomers, and plastics; A6817 Monolayers and Langmuir Blodgett films; A8115L Deposition from liquid phases melts and solutions; atomic force microscopy; cellulose monolayer; conducting polymers; electrodes; immobilization; INSPEC; Langmuir Blodgett deposition; Langmuir Blodgett films; metal electrode; metal electrodes; monolayers; nanofabricated electrode; nanofabricated electrodes; nanotechnology; one dimensional conducting polymer; phthalocyanine polymer; phthalocyanine polymers; phthalocyaninepolysiloxane; polymer films; rigid rod polymer","en","journal article","AIP for American Vacuum Soc","","","","","","","","","","","","",""
"uuid:4e58e2bc-5f69-4dbe-9942-aabcc9eaad35","http://resolver.tudelft.nl/uuid:4e58e2bc-5f69-4dbe-9942-aabcc9eaad35","Individual single-wall carbon nanotubes as quantum wires","Tans, S.J.; Devoret, M.H.; Dai, H.; Thess, A.; Smalley, R.E.; Georliga, L.J.; Dekker, C.","","1997","","140 nm; A6146 Structure of solid clusters, nanoparticles, and nanostructured materials; A7170E Spin orbit coupling, Zeeman, Stark and strain splitting condensed matter; A7320D Electron states in low dimensional structures; A7335 Mesoscopic systems and quantum interference; A7340L Electrical properties of semiconductor to semiconductor contacts, p n junctions, and heterojunctions; A7820L Magneto optical effects condensed matter; A7865J Optical properties of nonmetallic thin films; B2530C Semiconductor superlattices, quantum wells and related structures; C; carbon; carbon nanotube; carbon nanotubes; disorder; electrical conduction; electrical properties; electrical transport; electrical transport measurements; highly symmetric structures; individual single wall C nanotubes; individual single wall carbon nanotubes; INSPEC; magnetic field; mesoscopic systems; molecular quantum wires; molecular wavefunctions; multi wall nanotubes; nanostructured materials; nanotubes; quantum wires; Zeeman effect","en","journal article","Macmillan Magazines","","","","","","","","","","","","",""
"uuid:1f8b2797-50aa-4ec1-aa9c-ca052fd01f6f","http://resolver.tudelft.nl/uuid:1f8b2797-50aa-4ec1-aa9c-ca052fd01f6f","Thin films of the charge-density-wave oxide Rb(0.30) MoO(3) by pulsed-laser deposition","Mantel, O.C.; Van der Zant, H.S.J.; Steinfort, A.J.; Dekker, C.; Traeholt, C.; Zandbergen, H.W.","","1997","","182 K; A6855 Thin film growth, structure, and epitaxy; A7145L Charge density wave systems; A7215N Collective modes: low dimensional conductors; A7360 Electrical properties of thin films and low dimensional structures; A8115I Pulsed laser deposition; A8140E Cold working, work hardening: post deformation annealing, recovery and recrystallisation: textures; blue bronze; charge density wave; charge density wave chains; charge density wave oxide; charge density waves; epitaxial layers; heteroepitaxial growth; INSPEC; model; one dimensional conductivity; preferential orientation; pulsed laser deposition; Rb sub 0.30 MoO sub 3; resistance; rubidium compounds; single phase; SrTiO sub 3; SrTiO sub 3 100 substrates; substrate; texture; thin film; thin films; vapour phase epitaxial growth","en","journal article","APS through AIP","","","","","","","","","","","","",""
"uuid:64482b59-1f34-4070-afad-4853f2cf3bef","http://resolver.tudelft.nl/uuid:64482b59-1f34-4070-afad-4853f2cf3bef","Electrical transport in monolayers of phthalocyanine molecular wires and AFM imaging of a single wire bridging two electrodes","Tans, S.J.; Miedema, R.; Geerligs, L.J.; Dekker, C.; Wu, J.; Wegner, G.","","1997","","0.05 to 10 V; 135 to 360 K; 25 nm; A6817 Monolayers and Langmuir Blodgett films; A6820 Solid surface structure; A7220F Low field transport and mobility: piezoresistance semiconductors/insulators; A7340C Contact resistance, contact potential, and work functions; A7360F Electronic properties of semiconductor thin films; AFM; AFM imaging; atomic force microscopy; current voltage measurements; electrical contacts; electrical transport; electrodes; high resolution atomic force microscopy images; imaging; INSPEC; Langmuir Blodgett films; Langmuir Blodgett monolayer; metal electrode; metal electrodes; model; molecular electronics; molecular wire bridging; molecular wires; monolayers; organic compounds; organic semiconductors; phthalocyanine molecular wires; phthalocyaninepolysiloxane; Pt; single wire bridging; space charge limited conduction; space charge limited current model; substrate; synthetic metals; transport","en","journal article","Elsevier","","","","","","","","","","","","",""
"uuid:e6fe0e46-d049-4f3f-866d-905220f46cd5","http://resolver.tudelft.nl/uuid:e6fe0e46-d049-4f3f-866d-905220f46cd5","Charge transport in pi- and sigma-conjugated polymers","Van der Laan, G.P.","Hummel, A. (promotor); De Haas, M.P. (promotor)","1996","","conjugated polymers; radiation induced conductivity; charge carrier mobilities","en","doctoral thesis","","","","","","","","","Applied Sciences","","","","",""
"uuid:f5469a9f-533b-476b-bb9f-4875f8d4979d","http://resolver.tudelft.nl/uuid:f5469a9f-533b-476b-bb9f-4875f8d4979d","Thin-film growth of the charge-density-wave oxide Rb0.30MoO3","Van der Zant, H.S.J.; Mantel, O.C.; Dekker, C.; Mooij, J.E.; Traeholt, C.","","1996","","182 K; A6855 Thin film growth, structure, and epitaxy; A7145L Charge density wave systems; A7215N Collective modes: low dimensional conductors; A7360 Electrical properties of thin films and low dimensional structures; A8115I Pulsed laser deposition; CDW; CDW state; charge density wave; charge density wave oxide; charge density waves; electrical resistance; electrical resistivity; epitaxial layers; INSPEC; model; one dimensional conductivity; phase coherent CDW transport; pulsed laser deposition; Rb sub 0.30 MoO sub 3; resistance; rubidium compounds; single phase; single phase epitaxial films; SrTiO sub 3; substrate; thin film; thin films; transport; vapour phase epitaxial growth","en","journal article","AIP","","","","","","","","","","","","",""
"uuid:e770541c-17c8-4f74-ad94-1c95391283d9","http://resolver.tudelft.nl/uuid:e770541c-17c8-4f74-ad94-1c95391283d9","Dynamically compacted rechargeable ceramic lithium batteries. Solid state ionics - 95. Part II","Jak, M.J.G.; Kelder, E.M.; Stuivinga, M.; Schoonman, J.; Chowdari, B.V.R.","","1996","","Secondary cell Solid electrolyte storage battery Battery Lithium Manganese Oxides Energy density Dynamic compaction Ceramic materials Equivalent circuit Electrical impedance Frequency characteristic Temperature effect Electrical conductivity Boron Phospha","en","journal article","","","","","","","","","","","","","",""
"uuid:0158dd49-e3b6-4ae0-ba3c-031e9d9b39eb","http://resolver.tudelft.nl/uuid:0158dd49-e3b6-4ae0-ba3c-031e9d9b39eb","Combination of ac-impedance spectroscopy and short circuiting measurements applied on Yba2Cu3O7-. Solid state ionics - 95. Part II","Jak, M.J.G.; Riess, I.; Schoonman, J.; Chowdari, B.V.R.","","1996","","Electrical test Electrical impedance High frequency Short circuit Electrochemical cell Solid electrolyte Yttrium oxide Barium oxide Copper oxide Quaternary compound High temperature superconductor Stabilized zirconia Ionic conductivity Electronic conducti","en","journal article","","","","","","","","","","","","","",""
"uuid:8c62aff1-83a2-4d4f-854a-25a01cc547b7","http://resolver.tudelft.nl/uuid:8c62aff1-83a2-4d4f-854a-25a01cc547b7","Structural and electrical properties of dynamically compacted all-solid-state rechargeable lithium ion battery components","Jak, M.J.G.; Kelder, E.M.; Van Zomeren, R.A.; Schoonman, J.","","1996","","anodes- boron-compounds ceramics- densification- electrical-conductivity graphite- ionic-conductivity lithium- lithium-compounds phosphorus-compounds secondary-cells solid-electrolytes electrical-properties structural-properties dynamically-compacted soli; electrolyte","en","conference paper","Electrochem. Soc, Pennington, NJ, USA","","","","","","","","","","","","",""
"uuid:d1783e38-9a69-4208-ad34-c8de7a4f1e7f","http://resolver.tudelft.nl/uuid:d1783e38-9a69-4208-ad34-c8de7a4f1e7f","Electrical and interfacial properties of a Li3Fe2(PO4)3 single crystal with silver electrodes","Ivanov, S.A.K.; Schoonman, J.","","1996","","Electric conductivity Electric impedance Solid solid interfaces Monocrystals Temperature dependence Phase transformations DSC Ionic conductivity Solid electrolytes Activation energy Electrical model Equivalent circuits Twin boundary Experimental study Lit","en","journal article","","","","","","","","","","","","","",""
"uuid:26050d3a-88e4-4159-8ea0-89c66eea96f0","http://resolver.tudelft.nl/uuid:26050d3a-88e4-4159-8ea0-89c66eea96f0","A new ceramic lithium solid electrolyte for rechargeable swing type batteries","Kelder, E.M.; Jak, M.J.G.; deLange, F.; Schoonman, J.","","1996","","electrolyte; solid electrolytes ion conductivity lithium ion batteries ion conductivity","en","journal article","","","","","","","","","","","","","",""
"uuid:dc248e38-23c0-4589-a1e8-bfac9c8e341a","http://resolver.tudelft.nl/uuid:dc248e38-23c0-4589-a1e8-bfac9c8e341a","Microstructure-conductivity relationships in solid anisotropic ionically conducting materials","Butchereit, E.; Schoonman, J.; Zandbergen, H.W.; Lutz-Elsner, C.; Schreiber, M.; Wang, P.","","1995","","microstructure anisotropic ionically conducting material ionic conductor microstructure","en","conference paper","","","","","","","","","","","","","",""
"uuid:81b63591-297e-4f7f-99e9-3e4d8e96fb75","http://resolver.tudelft.nl/uuid:81b63591-297e-4f7f-99e9-3e4d8e96fb75","Charge carrier dynamics in pulse-irradiated columnar aggregates of mesomorphic porphyrins and phthalocyannines","Schouten, P.G.","Hummel, A. (promotor)","1994","","discotic liquid crystals; radiation induced conductivity; long range electron transfer","en","doctoral thesis","","","","","","","","","Applied Sciences","","","","",""
"uuid:e8ca360c-c6be-47d5-849c-ec0ee44cfced","http://resolver.tudelft.nl/uuid:e8ca360c-c6be-47d5-849c-ec0ee44cfced","Photophysical properties of opto-electric molecules studied by time-resolved microwave conductivity","Schuddeboom, W.","Hummel, A. (promotor)","1994","","Flash-photolysis; time-resolved microwave conductivity; dipole moments","en","doctoral thesis","","","","","","","","","Applied Sciences","","","","",""
"uuid:3b930bdb-1ff0-4d8d-b35f-f2952f5eca80","http://resolver.tudelft.nl/uuid:3b930bdb-1ff0-4d8d-b35f-f2952f5eca80","Mechanism of a 'Schottky-barrier-limited' Bi2Sr2CaCu2O8+x based sensor for CO and NO","Huang, X.J.; Schoonman, J.; Chen, L.Q.","","1994","","Measurement sensor Gas detector Carbon monoxide (ANA) Nitrogen monoxide (ANA) Semiconductor materials Porous material Polycrystal Thick film Chemisorption Reaction mechanism Schottky barrier Electrical conductance Temperature effect Partial pressure Gas m","en","journal article","","","","","","","","","","","","","",""
"uuid:a6c95d2e-c7b7-41c3-b608-c10c1ede80bb","http://resolver.tudelft.nl/uuid:a6c95d2e-c7b7-41c3-b608-c10c1ede80bb","Observations on the Na-Beta''-Alumina Metal Interface by Impedance Spectroscopy and Scanning Electron-Microscopy","Butchereit, E.; Schreiber, M.; Schoonman, J.","","1994","","sodium beta-aluminas ac impedance conductivity water","en","journal article","","","","","","","","","","","","","",""
"uuid:4d18a3aa-5a9c-4e87-9b94-a4202c854164","http://resolver.tudelft.nl/uuid:4d18a3aa-5a9c-4e87-9b94-a4202c854164","Mathematical modelling and numerical simulation of a two-phase heat transport system condenser","ten Dam, A.A.; van den Berg, J.I.","","1993","The mathematical modelling and numerical simulation of a condenser is discussed. This mathematical model is part of the NLR approach to model and scale two-phase heat transport systems (for space). During a previous study the condensation length required for various gravity conditions, and working fluids has been investigated by means of simulation studies. In this report the existing condensation model is extended with the effect of pure (radial) conduction via the growing condensate layer to the condenser wall. The effect of this extension is investigated by simulation studies.","condensates; condensers (liquefiers); conductive heat transfer; heat exchangers; heat transfer; mathematical models; pressure gradients; spacecraft temperature; thermal simulation; two phase flow","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:cb8add52-35d7-4441-addc-2c15aa41c2a2","http://resolver.tudelft.nl/uuid:cb8add52-35d7-4441-addc-2c15aa41c2a2","Polycrystalline, glassy and thin films of LiMn2O4","Chen, L.; Schoonman, J.","","1993","","Electric conductivity Electric impedance Thin films Vitreous state XRD Sintering Lattice parameters Polycrystals Self diffusion Experimental study DTA Manganites Lithium compounds Manganese oxides Ternary compounds Conductivite electrique Impedance electr","en","journal article","","","","","","","","","","","","","",""
"uuid:1289bc1c-8427-4366-9ad2-5f04f5d92808","http://resolver.tudelft.nl/uuid:1289bc1c-8427-4366-9ad2-5f04f5d92808","Synthesis of Strontium and Barium Cerate and Their Reaction with Carbon-Dioxide","Scholten, M.J.; Schoonman, J.; Van Miltenburg, J.C.; Oonk, H.A.J.","","1993","","bulk protonic conduction yb-doped srceo3 solid electrolyte ion conduction baceo3","en","journal article","","","","","","","","","","","","","",""
"uuid:ccf95c64-7e20-42b2-a682-f814b9330088","http://resolver.tudelft.nl/uuid:ccf95c64-7e20-42b2-a682-f814b9330088","Electrical properties of SrCe095Yb005O3 in hydrogen containing atmospheres","Kosacki, I.; Becht, J.G.M.; Van Landschoot, R.; Schoonman, J.","","1993","","Experimental study Electrical conductivity Ionic conductivity Proton conductivity Controlled atmosphere Raman scattering Inorganic compound Cerium Strontium Ytterbium Oxides Mixed Etude experimentale Conductivite electrique Conductivite ionique Conductivi","en","journal article","","","","","","","","","","","","","",""
"uuid:105c83ec-6c79-4296-9ddb-2b49128dc0f1","http://resolver.tudelft.nl/uuid:105c83ec-6c79-4296-9ddb-2b49128dc0f1","Magnetic field effects on switching noise in a quantum point contact","Liefrink, F.; Scholten, A.J.; Dekker, C.; Dijkhuis, J.I.; Alphenaar, B.W.; Van Houten, H.; Foxon, C.T.","","1992","","A7220M Galvanomagnetic and other magnetotransport effects semiconductors/insulators; A7270 Noise processes and phenomena in electronic transport; A7320A Surface states, band structure, electron density of states; A7340L Electrical properties of semiconductor to semiconductor contacts, p n junctions, and heterojunctions; aluminium compounds; conduction band; conduction band bottom; conduction bands; fluctuations; g factor; GaAs Al sub x Ga sub 1 x As; gallium arsenide; III V semiconductors; INSPEC; interface electron states; Lande g factor; magnetic field; magnetic field effects; model; noise; point contacts; quantum Hall effect; quantum Hall regime; quantum point contact; quantum size effect; random noise; semiconductor; size effect; switching noise; temporal electrostatic fluctuations; transconductance; zero magnetic field","en","journal article","","","","","","","","","","","","","",""
"uuid:ebcf8519-235a-43ea-9761-42f6c332b9af","http://resolver.tudelft.nl/uuid:ebcf8519-235a-43ea-9761-42f6c332b9af","Raman scattering and ionic transport in SrCe1-xYbxO3","Kosacki, I.; Schoonman, J.; Balkanski, M.","","1992","","Experimental study Ionic conductivity Raman scattering Dielectric loss Vibrational mode Spectral line width Intensity Temperature High temperature Thermal annealing Controlled atmosphere Solid solution Chemical composition Vacancy Inorganic compound Ceriu","en","journal article","","","","","","","","","","","","","",""
"uuid:5708bd3d-2ef1-40a0-a86c-1931f0c74bc4","http://resolver.tudelft.nl/uuid:5708bd3d-2ef1-40a0-a86c-1931f0c74bc4","Na2SO4-based solid electrolytes for SOx sensors","Rao, N.; Schoonman, J.; Sorensen, O.T.","","1992","","Air pollution Sulfur Oxides Solid electrolyte Sodium Sulfates Measurement sensor Yttrium Sulfates Lanthanum Sulfates Sodium Tungstates Electrical conductivity Pollution air Soufre Oxyde Electrolyte solide Sodium Sulfate Capteur mesure Yttrium Sulfate Lant; electrolyte","en","journal article","","","","","","","","","","","","","",""
"uuid:67408fa6-8c22-4586-95b4-9a73322605ee","http://resolver.tudelft.nl/uuid:67408fa6-8c22-4586-95b4-9a73322605ee","Low-frequency noise of quantum point contacts in the ballistic and quantum Hall regime","Liefrink, F.; Scholten, A.J.; Dekker, C.; Eppenga, R.; Van Houten, H.; Foxon, C.T.","","1991","","A7220M Galvanomagnetic and other magnetotransport effects semiconductors/insulators; A7270 Noise processes and phenomena in electronic transport; A7335 Mesoscopic systems and quantum interference; backscattering; ballistic regime; conductance; electrostatic potential; fluctuations; INSPEC; low frequency noise; magnetic field; noise; point contacts; quantum Hall effect; quantum Hall regime; quantum interference phenomena; quantum point contact; quantum point contacts; resistance; resistance noise; spin degeneracy; strong magnetic field","en","journal article","","","","","","","","","","","","","",""
"uuid:06a694bc-6bdc-4bf3-9014-8eeac94a7623","http://resolver.tudelft.nl/uuid:06a694bc-6bdc-4bf3-9014-8eeac94a7623","Spontaneous resistance switching and low-frequency noise in quantum point contacts","Dekker, C.; Scholten, A.J.; Liefrink, F.; Eppenga, R.; Van Houten, H.; Foxon, C.T.","","1991","","A7220J Charge carriers: generation, recombination, lifetime, and trapping semiconductors/insulators; A7270 Noise processes and phenomena in electronic transport; A7320D Electron states in low dimensional structures; A7340L Electrical properties of semiconductor to semiconductor contacts, p n junctions, and heterojunctions; carrier mobility; charge transport; conductance; electron device noise; electron traps; electrostatic potential; frequency dependence; INSPEC; local electrostatic potential; low frequency noise; low frequency noise spectroscopy; model; noise; point contacts; quantum point contact; quantum point contacts; quantum size effect; resistance; resistance switching; semiconductor quantum dots; semiconductors; size effect; spectral density; temperature dependence; transport; trapping; white noise","en","journal article","","","","","","","","","","","","","",""
"uuid:181be43c-d42a-4fe4-837c-2840a856a768","http://resolver.tudelft.nl/uuid:181be43c-d42a-4fe4-837c-2840a856a768","Mixed ionic-electronic conduction in HTcS","Vischjager, D.J.; Schram, J.; Mackor, A.; Schoonman, J.","","1989","","electrolyte; ionic electronic cond superconductors cuprate barium yttrium cuprate ionic conduction europium barium cuprate ionic conduction lanthanum strontium cuprate ionic conduction","en","conference paper","","","","","","","","","","","","","",""
"uuid:d5376553-b8b6-4bc9-b631-554eb02e0100","http://resolver.tudelft.nl/uuid:d5376553-b8b6-4bc9-b631-554eb02e0100","Oxygen diffusion in YBa2Cu3O7-x; an impedance spectroscopy study","Vischjager, D.J.; Van der Put, P.J.; Schram, J.; Schoonman, J.","","1988","","Experimental study Ionic conductivity Electrical conductivity Superconducting transition Activation energy Vacancy Oxygen Stoichiometry Self diffusion Low temperature High temperature Temperature High temperature superconductor Oxide ceramics Inorganic co","en","journal article","","","","","","","","","","","","","",""
"uuid:64c9816c-0213-417c-9032-3c1ed08a7d77","http://resolver.tudelft.nl/uuid:64c9816c-0213-417c-9032-3c1ed08a7d77","Considerations concerning a thermal joint for a deployable or steerable battery radiator for the Columbus Polar Platform","Delil, A.A.M.","","1986","Different concepts for a moveable thermal joint are described and discussed with respect to the applicability in a dedicated deployable or steerable heat pipe radiator system to handle the waste heat of the NiH batteries of the Polar Platform. Concepts which are identified as possible candidates for near-term deployable radiator development are: - the flexible heat pipe; - the low-melting-point alloy filled, grease filled or low pressure helium gas filled (finned) heat exchanger; - the braided conductor (having high mass and retraction torque); - the clamped contact. The flexible heat pipe can be considered to be less attractive for steerable radiator applications. For such radiators the braided conductor and the clamped contact are inadequate. Consequently the non-solid material filled heat exchanger is the preferable joint if steerability is required","European space programs; Spacecraft temperature; Heat radiators; Heat pipes; Two phase flow; Joints (junctions); Thermal conductivity; Space platforms; Temperature control; Heat exchangers; Working fluids; Trade offs; Thermal conductors","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:a54afc7d-6aaa-4e52-a816-94b47a6aeb72","http://resolver.tudelft.nl/uuid:a54afc7d-6aaa-4e52-a816-94b47a6aeb72","Limitations in variable conductance heat pipe performance and control predicted by the current steady-state model developed at NLR","Delil, A.A.M.","","1984","A uniaxial model for the transient performance of gas-loaded variable conductance heat pipes is being developed, partly under contract with the Netherlands Agency for Aerospace Programs NIVR. The model has to be easily implementable in existing spacecraft thermal analyzer computer programs. So far, a steady-state version of the model is available. It accounts for diffusion at the vapour/gas front (shown to be negligible), radial conduction in the wall and wick, and inertia and friction of the moving vapour. A parameter study was carried out to design a heat pipe and to define test conditions for the experimental verification of the model. Typical results are presented, illustrating that under certain conditions inertia and friction can induce considerable limitations in performance and control. Contribution for the International Heat Pipe Conference, Tsukuba, Japan, 14-18 May, 1984.","variable conductance heat pipe; mathematical modelling; gas-loading; thermal control; temperature control; flat front theory; friction; inertia","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:7cd1976d-03ac-4d77-bb34-a558e13f7505","http://resolver.tudelft.nl/uuid:7cd1976d-03ac-4d77-bb34-a558e13f7505","Uniaxial model for gas-loaded variable conductance heat pipe performance : the effects of vapour flow friction and inertia","Delil, A.A.M.; Daniels, H.A.M.","","1983","","variable conductance heat pipe; gas-loading; mathematical Modelling; thermal control; flat front theory; temperature control; friction; inertia","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:9dd4ab10-7c19-4b3e-a4ba-0d17a99513eb","http://resolver.tudelft.nl/uuid:9dd4ab10-7c19-4b3e-a4ba-0d17a99513eb","Determination of the thermal conductivity of carbon fibre reinforced plastic sheet material","van der Assem, D.; Daniels, D.H.W.","","1977","","carbon fibre reinforced plastics; composite materials; anisotropy; thin sheet material plates; thermal conductivity; contact resistance; surface temperature; thermal conductivity gages; temperature gradient; thermal insulation; thermo couples; surface layers","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:0df4af9d-a7b2-4768-a0f6-a98e8a8c7e7e","http://resolver.tudelft.nl/uuid:0df4af9d-a7b2-4768-a0f6-a98e8a8c7e7e","A theoretical investigation of gas conduction effects on multilayer insulation performance","Delil, A.A.M.; Heemskerk, J.F.","","1976","The thermal performance of multilayer insulation hlankets depends on three (interacting) modes of energy transfer: radiation between the radiation shields, gas conduction in the residual interstitial gas and solid conduction via the contacting interfaces. The contribution of the gas conduction depends on the interstitial gas and its pressure, that are determined mainly by the temperature dependent outgassing of the shield and spacer materials. Special attention has been given to the actual problems of the insulation of the storage of cryogenic licpiids in vessels, the insulation of black boxes from space environment and the effect of gas sources surroimded by multilayer insulation. The results indicate that perforation of the shields reduces the insulation properties of a blanket considerably. Hence for cryogenic storage non-perforated shields are to be preferred. In space cutted shields are to be preferred, because they allow fast depressurisation without impairing the radiation properties.","heat transfer; multilayer insulation; spacecraft shielding; heat transfer coefficients; mathematical models; thermal conductivity; gaseous diffusion; thermal diffusion; thermal insulation; cryogenic fluid storage; outgassing","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:630fa04f-9708-41a1-8d4b-ce0dc1c2f949","http://resolver.tudelft.nl/uuid:630fa04f-9708-41a1-8d4b-ce0dc1c2f949","Induction heating of mastic containing conductive fibers and fillers","García, Á.; Schlangen, E.; Van de Ven, M.; Van Vliet, D.","","","The objective of this research is to examine the induction heating of mastic through the addition of electrically conductive fillers and fibers (graphite and steel wool), and to prove that this material can be healed with induction energy. The effect of fibers content, sand–bitumen ratio and the combination of fillers and fibers on the induction heating of mastic was investigated. It was found that there is an optimum content of fibers for each sand–bitumen ratio, above which mastic cannot be heated any more. This optimum seems to coincide with the optimum electrical conductivity of the mixture shown in [1]. It was found that the maximum temperature reached within a certain time period was a function of the sand–bitumen ratio (s–b) and of the volume content of fibers. The mastic could be heated with the addition of a very low volume of conductive fibers. The fastest heating power was obtained with the mix with the maximum electrical conductivity. Gel-Permeation Chromatography (GPC) was also used to show that there is not ageing of bitumen during the heating process.","induction heating; conductive mastic; steel wool; graphite; self-healing","en","journal article","Springer","","","","","","","","Civil Engineering and Geosciences","Design and Construction","","","",""
"uuid:f388c4ad-4ab2-4dd0-9b86-b1af08953cd0","http://resolver.tudelft.nl/uuid:f388c4ad-4ab2-4dd0-9b86-b1af08953cd0","Crack repair of asphalt concrete with induction energy","García, A.; Schlangen, E.; Van de Ven, M.; Van Vliet, D.","","","It is well known that the healing rates of asphalt courses increase with the temperature. A new method, induction heating, is used in this paper to increase the lifetime of asphalt concrete pavements. Mastic will be first made electrically conductive by the addition of conductive fibers. Then it will be heated via induction energy. This will repair the damage in the pavement, closing the cracks that could have appeared during its lifetime. Adding too much heat will melt the binder completely and the properties of the material will be lost. In the paper it is shown how this method can be repeated many times for samples that are completely broken and that the evolution of the mechanical resistance of specimens that are broken is limited. It will also be shown how the chemical properties of the bitumen do not change due to heating.","Induction heating; conductive mastic; steel wool; self healing","en","journal article","","","","","","","","","","","","","",""