Negative linear compressibility (NLC) describes the relative increase or decrease in a material's linear dimension when subjected to an increase or decrease in external pressure, or a decrease or increase in internal pressure, respectively. This is a rare material property found in only a few naturally existing materials. These materials are not only limited by their availability but also by the range, strength, and stability of NLC behavior. This limitation can be addressed through the design of NLC metamaterials, which are engineered materials composed of repeating architectures or material layouts on the microscopic scale, known as base or unit cells. These cells define the macroscopic properties of the material. In this case, negative linear compressibility. While there are different methods for designing NLC metamaterials, none of them involve the use of topology optimization (TO), which serves as a powerful tool for designing optimized metamaterial structures. Materials can be designed for different parameters such as base material and pressure applied, while also considering different constraints that may be application-specific. This study aims to create isotropic NLC metamaterials by designing NLC metamaterial unit cells using a systematic design methodology. We achieve this goal using a density-based TO approach, incorporating different constraints and selecting appropriate parameters to obtain different metamaterial unit cells that exhibit NLC behavior in both two and three dimensions. The resulting 2D designs exhibited an NLC value of -2.370 %/bar and -3.367 %/bar. While the 3D designs exhibited an NLC value of -2.212 %/bar and -3.534 %/bar. The obtained NLC value and the efficacy of the design method are validated through numerical analysis and experimental testing, with the experimental design showing a maximum deviation of 26.099% from the NLC value obtained through TO. Finally, comparative and parameter studies helped better elucidate the advantages, limitations, and areas for improvement of the methodology used to obtain these designs.

Neural Radiance Fields (NeRFs) have showcased remarkable effectiveness in capturing complex 3D scenes and synthesizing novel viewpoints. By inherently capturing the entire scene in a compact representation, they offer a promising avenue for applications such as simulators, where efficient storage of real-world data, fast rendering and dynamic generation of new content are crucial. However, the potential for compression in NeRFs has been largely neglected in the existing literature. Moreover, the practical deployment of NeRFs in real-world scenarios, including simulators, faces significant obstacles such as constraints in training time, rendering speed, and scalability to large scenes. While recent advancements have tackled some of these hurdles individually, none have offered a comprehensive solution. In this paper, we introduce a new NeRF architecture based on a textured polygon-based method and augment this architecture by integrating encodings to expedite training. Additionally, we introduce learned pose refinement and an appearance embedding to enhance scalability to larger scenes. Through experimentation on the nuScenes dataset, we demonstrate that our method achieves competitive reconstruction performance with existing techniques while surpassing them in rendering speed. Furthermore, in terms of compression, our findings indicate that our method achieves competitive compression rates comparable to image-based compression techniques, while also enabling novel-view synthesis. This underscores its potential utility in applications like simulators.

As Neuroscience progresses, there is an increasing amount of research that endorses predictions and reducing of prediction errors as one of the main functions of the brain. active inference is a brain-inspired, mathematical framework that successfully implements this idea both in simulations as well as in robotics. The predictive nature of active inference might make current artificial intelligence agents more adaptive. However, the motives of these agents are often still hardwired as attractor dynamics or learnt using over-engineered rewards. Nature has come up with a different way of providing intelligent beings with drives for their actions: affect, more commonly known as emotions. Although various models integrate affect into active inference , none have yet applied Mark Solms' definition within a continuous active inference framework. According to Solms' interpretation, affect acts as an evaluative monitoring mechanism of an organism's homeostatic states and guides it through unpredictable environments. This active monitoring of homeostatic states is what according to Solms stands on the basis of consciousness. Key here is the prioritization of different homeostatic needs, where deviations in the most salient category of need come to the organism's affective(conscious) awareness. Mark Solms proposes that computationally, affect is constituted by the inference of changes in precision. Where increases in precision are positively- and decreases in precision are negatively valenced. This change in precision is obtained by performing a gradient descent on free energy with respect to precision, which results in an incremental precision updating scheme that determines the salience of prediction errors. This offers an adaptable mechanism that allows context, through precision modulation, to determine the relative influence of prediction errors.  This in turn allows an agent to prioritize homeostatic needs i.e. letting certain needs come to conscious awareness. "Context" in the light of Solms' research is defined as either: the relation of needs with respect to other needs or the relation of needs with respect to external opportunities. This research supports Solms' theory on affect and consciousness by successfully providing a computational implementation that can, through precision optimization, perform the prioritization of needs directed by "context" as just defined. By doing this successfully, this research shows that the principles used could potentially be useful in continuous active inference implementations, improving their adaptability.  

The rising number of objects in low Earth orbit heightens the likelihood of orbital debris impact on spacecrafts at an increasingly fast pace. Thus, the need for lightweight shielding from hypervelocity impacts has grown considerably. Direct observation of hypervelocity impacts are almost impossible and experimental campaigns are expensive, and so numerical simulation has become a fundamental tool for hypervelocity impact modelling. These simulations involve multiple coupled physics mechanism, including fragmentation and stress waves propagation. While various simulation techniques exist for this problem, none effectively capture the interaction between fragmentation and stress wave propagation within the velocity range relevant to orbital impacts while being suitable for modelling of full-scale satellite fragmentation events. The objective of this thesis is to address this limitation by proposing an approach for a fragmentation framework based the Discontinuous Galerkin/Cohesive Zone Method finite element formulation and the Decomposition Contact Response contact algorithm.

It is observed that the bed level development of the Pannerden Canal (PC) and the Waal changed since the peak flows of 1993, 1995 and 1998. The erosion rate of the Pannerden Canal decreased greatly just downstream of the bifurcation while the erosion rate of the Waal stayed more or less constant. This leads to an increasing depth of the Waal relative to the Pannerden Canal and therefore the Waal attracts more discharge. The model results from this study confirm that without anthropogenic interventions in the future, the Waal discharge fraction keeps increasing. The shift in discharge partitioning towards the Waal is an undesired development of the system as it causes problems for navigability, ecology, freshwater distribution and flood safety. Currently there is a lack of knowledge on how interventions can be used to mitigate the gradual change in discharge partitioning at the Pannerdense Kop (PK). This study aims at filling the knowledge gap by considering several interventions studying their effect on the discharge partitioning at the PK and on the Rhine branches surrounding the PK. Firstly, an inventory of interventions which could possibly increase the Waal discharge fraction is made. The resulting selection of interventions is: A) a side channel from the Boven-Rijn towards the PC, B) fully opening the weirs in the NR-Lek, C) widening on the IJssel, D) directly steering the sediment partitioning at the PK and E) dredging in the PC and dumping in the Waal. These interventions are implemented in a 1D-morphological model of the Dutch Rhine branches. It is found that the side channel from the Boven-Rijn to the PC (A) is not capable of significantly influencing the discharge partitioning at the PK. The backwater effects due to the water addition counteract the added discharge to the PC. Furthermore, it is found that for the low Lobith discharges opening the weirs in the NR-Lek (B) can reduce the Waal discharge fraction below the initial value from the reference case for the whole simulated period of 60 years. The opening of the weirs does however lead to significant relative decrease in the IJssel discharge fraction which is unwanted regarding the freshwater supply of the IJsselmeer. For low Lobith discharges the widening on the IJssel (C) initially leads to a significant reduction in Waal discharge fraction of 2.4%. The effectivity reduces throughout the simulation because of aggradation along the widened reach. For high flows the opening of the weirs and the IJssel widening are less effective. The final relative Waal discharge fraction decrease is respectively 1.1% and 0.7%. The results of the directly steering the sediment partitioning (D) are similar for high and low flows. The water level is not changed initially and therefore initially the discharge partitioning is not affected. Throughout the simulation the slope of the Waal adjusts to the increased sediment supply and the slope of the PC adjusts to the decreased sediment supply. For both flows the final relative decrease in Waal discharge fraction is 1.8%. Dredging and dumping (E) shows similar effects on the bed level and discharge partitioning as steering the sediment partitioning at the PK. Dredging and dumping also does not alter the water level and the discharge partitioning initially. The relative bed level increase of the Waal is somewhat higher for the dredging and dumping simulation than for the simulation in which the sediment partitioning at the PK is steered. Therefore also the relative decrease in Waal discharge fraction is higher with 2.4% for the low Lobith flows and 2.2% for the high Lobith flows. Currently the IRM program aims at stopping further skewing of the discharge partitioning of the PK. None of the interventions from this study is capable of realising this on its own. Therefore multiple river interventions will have to be combined to be able to reach the ambitions of IRM. The knowledge on the effect of the interventions on the discharge partitioning at the PK and the bed levels of the Dutch Rhine branches can be used as a basis for further study towards to combined effects of river interventions on the bed level development of the Dutch Rhine branches and the discharge partitioning at the PK.

This thesis addresses the detection and prevention of adversarial attacks on self-triggered control (STC) systems and demonstrates how manipulating the sampling times can be used to provide a secure control framework. Secure control is vital to guarantee both the safety and security of critical infrastructure, which has been the target of malicious attacks over the past decade. First, a novel watermarking scheme is proposed based on the early triggering of a well-designed STC policy, such that stability is guaranteed to be preserved. We show that this watermarking scheme, together with an event-triggered χ2 detector we design, is able to detect replay attacks. An online heuristic for obtaining an optimal early triggering policy is provided. If certain assumptions hold we show that the early triggering policy is a discrete uniform one. Through an illustrative example, both a quantitative and qualitative comparison between two other watermarking schemes are provided. We conclude that none of the watermarking schemes can claim absolute superiority, and trade-offs between all considered schemes exist. Next, we propose a new type of attack called a switched zero dynamic attack (ZDA), and provide an algorithm on how to construct these switched ZDA. We show that certain STC systems are susceptible to such attacks, and demonstrate that by tuning the triggering parameters there exist sufficient conditions such that these attacks are no longer disruptive. The effect of additive perturbations and a non-zero initial condition, as well as the proposed tuning method, are shown in a numerical example. We provide a qualitative comparison between several other countermeasures in the literature, which we extend for aperiodic sampling when needed. Finally, shortcomings and future directions are discussed.

This study investigates the effect on the principal aerodynamic forces caused by home-built under-wing attachments excluding possible consequences on the aircraft’s control and manoeuvrability. Many other types of wing attachment have already been used and investigated of time. However, none of these attachments match exactly the attachment under investigation in this study. For aerial display purposes, one of the team members of the Whiskey Formation Team created an under-wing firework launch platform attached to the tie-down points of the aircraft. These tie-down points are fixed to the quarter chord wing spar at about 90% of the half wing span near the wingtip. The launch platforms themselves protrude about a quarter of their own length in front of the wing’s leading edge. The remaining part is attached flush with the wing’s lower skin. After installing the attachments on the aircraft’s wing, the creator took it upon himself to do some trial high speed taxi runs followed by a standard take-off. A circuit around the field and a full stop landing completed his trial run during which no adverse effects on the aircraft handling or flight safety could be detected. Next, on the first trial flight as a formation with the launch platforms attached, the team leader claimed he experienced a slight performance increase. Earlier lift-off and sharper turns were among the examples of this performance increase he gave. No claims on the aircraft’s fuel consumption, cruising speed or power-off gliding performance were made. This was not investigated and is deemed not to be relevant to the aerial display. This report investigates these claims by modelling the aircraft for computational flow simulations, with and without the platforms attached, for both take-off and high G-load turns. For the take-off condition a runway surface is modelled at a wheels-height distance from the aircraft’s wing. Realistic speeds of 50 and 60 knots respectively are chosen together with 10 degrees of geometrical pitch. The result of these simulations was then validated in real life circumstances to eliminate possible adverse results due to modelling error of the real life aircraft. A number of comparative test flights, 5 in total with 6 take-offs per flight, were performed registering weight and take-off speed for a trimmed stick-free configuration. The results obtained from these test flights are likely to confirm the results obtained from the simulations. For the simulations, a larger lift and lower drag force are noted for the configuration with the launch platform attached for The steep turn case. For the take-off case a drag increase was noted. In the real life test this could be confirmed by the almost identical take-off velocities even though this falls well within the error margin of the experimental setup. The gain in lift, most pronounced for the steep turn case, comes from the blocking of the spanwise flow by the launch platforms hereby likely reducing the lift-induced drag caused by the wing tip vortex. The total drag of the modelled wing is reduced for the steep turn case even though the launch platforms contribute to the friction drag. Moreover, the model’s lift-to-drag ratio, a common measure of aircraft’s performance, is increased. It can therefore be concluded that for the investigated cases indeed a small effect of the launch platforms on the aircraft’s performance can be found though it is deemed unlikely that this difference is be noticeable. Real life tests only show little promise since the error margin occludes the effects on performance. For flight display purposes a different meaning of the word ’performance’ is meant. The lift force is considered much more important than the drag force, even though the drag force is reduced too. Therefore it can be concluded that the installation of the launch platforms does not adversely affect the aircraft’s performance parameters such as lift and drag. Moreover, it is plausible that they do improve the aircraft’s performance parameters and do improve the performance of the aircraft for aerial display purposes.

This study investigates the effect on the principal aerodynamic forces caused by home-built under-wing attachments excluding possible consequences on the aircraft’s control and manoeuvrability. Many other types of wing attachment have already been used and investigated of time. However, none of these attachments match exactly the attachment under investigation in this study. For aerial display purposes, one of the team members of the Whiskey Formation Team created an under-wing firework launch platform attached to the tie-down points of the aircraft. These tie-down points are fixed to the quarter chord wing spar at about 90% of the half wing span near the wingtip. The launch platforms themselves protrude about a quarter of their own length in front of the wing’s leading edge. The remaining part is attached flush with the wing’s lower skin. After installing the attachments on the aircraft’s wing, the creator took it upon himself to do some trial high speed taxi runs followed by a standard take-off. A circuit around the field and a full stop landing completed his trial run during which no adverse effects on the aircraft handling or flight safety could be detected. Next, on the first trial flight as a formation with the launch platforms attached, the team leader claimed he experienced a slight performance increase. Earlier lift-off and sharper turns were among the examples of this performance increase he gave. No claims on the aircraft’s fuel consumption, cruising speed or power-off gliding performance were made. This was not investigated and is deemed not to be relevant to the aerial display. This report investigates these claims by modelling the aircraft for computational flow simulations, with and without the platforms attached, for both take-off and high G-load turns. For the take-off condition a runway surface is modelled at a wheels-height distance from the aircraft’s wing. Realistic speeds of 50 and 60 knots respectively are chosen together with 10 degrees of geometrical pitch. The result of these simulations was then validated in real life circumstances to eliminate possible adverse results due to modelling error of the real life aircraft. A number of comparative test flights, 5 in total with 6 take-offs per flight, were performed registering weight and take-off speed for a trimmed stick-free configuration. The results obtained from these test flights are likely to confirm the results obtained from the simulations. For the simulations, a larger lift and lower drag force are noted for the configuration with the launch platform attached for The steep turn case. For the take-off case a drag increase was noted. In the real life test this could be confirmed by the almost identical take-off velocities even though this falls well within the error margin of the experimental setup. The gain in lift, most pronounced for the steep turn case, comes from the blocking of the spanwise flow by the launch platforms hereby likely reducing the lift-induced drag caused by the wing tip vortex. The total drag of the modelled wing is reduced for the steep turn case even though the launch platforms contribute to the friction drag. Moreover, the model’s lift-to-drag ratio, a common measure of aircraft’s performance, is increased. It can therefore be concluded that for the investigated cases indeed a small effect of the launch platforms on the aircraft’s performance can be found though it is deemed unlikely that this difference is be noticeable. Real life tests only show little promise since the error margin occludes the effects on performance. For flight display purposes a different meaning of the word ’performance’ is meant. The lift force is considered much more important than the drag force, even though the drag force is reduced too. Therefore it can be concluded that the installation of the launch platforms does not adversely affect the aircraft’s performance parameters such as lift and drag. Moreover, it is plausible that they do improve the aircraft’s performance parameters and do improve the performance of the aircraft for aerial display purposes.

The availability of laparoscopy in low-income settings has been limited based on the requirements that have to be met to perform this type of abdominal surgery. At the same time, these regions and countries could stand to gain the most from it based on quicker recovery times and a lower chance of infections. Attempts have been made to solve this inaccessibility by minimizing the required components to perform this type of surgery at a substantially lower cost. None of these projects have resulted in a laparoscope that can compete with commercial laparoscopes regarding resolution, image quality, and critical design features such as viewing angle. Based on these shortcomings, this study aims to design a sub-500-dollar modular laparoscope for gas and gasless laparoscopy that adheres to state-of-the-art image quality and design features. The laparoscopes are designed following the 'Roadmap for Design of Surgical Equipment for Safe Surgery Worldwide”. Based on the roadmap requirements regarding the needs of patients, end-users, and stakeholders, were acquired focusing on cost, robustness, and reusability. Following the design process, two intermediate prototypes were developed, which were evaluated based on function and image quality by a laparoscopic surgeon to validate the requirements and receive design feedback. They resulted in a modular laparoscope that connects with USB to a laptop, which shares the image sensor, light source, electronics, and handle between the laparoscope for gas and gasless laparoscopy. The gasless laparoscope employs a flexible chip-on-the-tip design that can be straightened for entry through a trocar and released to set the tip angle at 30 degrees. The gasless laparoscope does not have to comply with the trocar and can enter straight through the abdominal entry point. Resulting in a chip-on-the-tip design, which is statically bent at an angle of 30 degrees. To validate the design, a laparoscopic surgeon evaluated the function and image quality, and additional tests were performed to validate the thermal and reprocessing capability. The study resulted in a modular sub-500-dollar laparoscope for gas and gasless laparoscopy, which shows great potential but requires future work to be certified and production-ready.

The Bajau Laut or Sama Dilaut people are an ethnic group of sea nomads who used to roam between the Filipino, Malaysian, and Indonesian maritime zones. The Bajau are known to be amazing freedivers, being able to dive in depths of up to 30 meters and having the ability to hold their breath for more than 5 minutes, making them a group of people that biologically adapted into an amphibious lifestyle. In 1877, most present-day Sabah, Malaysia, was surrendered to the newly constituted British North Borneo Chartered Company. The reforms constituted by the Company gradually forced them to self-build the first pile house setlements in 1955 and abandon nomadism for a sedentary lifestyle along the shore in 1979. Due to their nomadic lifestyle in the past, none of the three SE Asian countries have recognized the community as indigenous people, making them stateless and hence depriving them of the right to civil registry, subsidized healthcare and education with the exception of Alternative Learning centers that are run by NGOs and volunteering teachers. However, what is the position of Alternative Learning Centers regarding indigenous educa􀆟on and the importance of school as an establishment? Alternative learning centers offer basic literacy classes such as Malay language and Mathematics. Still, volunteering, uncertified teachers have the freedom to improvise by introducing classes related to their major or the children’s wishes. However, only a small part of the curriculum has anything to do with the community’s traditional ecological knowledge or identity. How do we define literacy nowadays? What deems a person illiterate? This project aims to redefine schooling by introducing a culturally responsive curriculum in a community waterscape that acts as a mediator between the community's built environment and the surrounding marine landscape, prioritizing knowledge stemming from both environments.

Food loss and waste (FLW) generation is a global issue that has recently gained an increasing attention. It has previously been estimated that approximately one third of all food globally produced is wasted. Recently, other accounts have been made, for various food products and focusing on various geographical scopes, sometimes disaggregating between various qualities of FLW, but none was found to quantify FLW per quality at the global level. This would be a pertinent addition to the ongoing research, as the type of treatment (or valorisation) possible is dependent on the type of FLW, and this would be of great relevance in the global actions towards the achievement of the Sustainable Development Goal (SDG) 12.3 aiming at the reduction of food loss and food waste globally by halve by 2030. Additionally, recent literature focuses on avoidable FLW or does not separate between avoidable and unavoidable, although it is essential to address unavoidable FLW on its own as by its nature it cannot simply be prevented and its generation should thus be appropriately managed. Therefore, this thesis project aimed at answering how much food is currently being lost and wasted regarding fruits and vegetables at the global level and how it can be valorised. In the first part of the research, a Material Flow Analysis (MFA) was conducted at the global level to quantify unavoidable loss generated at the processing stage and unavoidable waste generated at the retail and consumption stages. The results show that the fruit value chain generates more unavoidable loss and waste than the vegetable value chain and that the retail and consumption stages generate more unavoidable waste than the processing stage of unavoidable loss. Additionally, regional hotspots were identified. In the second part of the research, an assessment of the valorisation pathways is conducted on the category of loss and waste streams identified as the most problematic by the MFA results, which was fruit and vegetable peel. The valorisation assessment was conducted following the concept of the FLW management hierarchy, which ranks the various end-of-life (EoL) treatments by prioritizing the most environmental-friendly and resource-efficient ones. In this study, the potential of fruit and vegetable peel loss and waste for reuse in food and feed, for the production of biobased materials, biofertilizers as well as biofuels was explored and quantified. The results suggest that an optimal FLW management system should be an adequate mix of various valorisation pathways. In regard to the SDG 12.3, efforts should aim on the one hand at preventing FLWthat can be avoided and on the other hand at valorising FLW that cannot be avoided.

The electrical power system is a critical infrastructure that provides a reliable energy supply for daily businesses. Designing resilient and reliable power grids is of paramount importance to prevent blackouts and their adverse economic impact on society. Resiliency is fundamentally defined as the ability of a system to respond to high-impact disturbances with a low-probability of occurrence. Evaluating resiliency in power systems is usually done in three stages. The first phase is the disturbance progress. During the first phase, the resilience level deviates from its pre-disturbance level. This can be observed by analyzing different metrics in the network. Secondly, in the case of effective primary control actions, a new steady state operating condition is reached, which differs from the pre-disturbance operating condition. Finally, the system reaches the restorative stage. The recovery starts and the system returns to normal operation. The assessment of resiliency is a combination of assessing all three previously mentioned stages (during-disturbance, post-disturbance, and restorative). Depending on the focus of the study, different technical aspects of a system are assessed. This thesis focuses on the assessment of the during-disturbance phase because, in future grids with lesser reserves available and limited control capabilities, the initial response of the system following a disturbance becomes more critical. This thesis presents a basic qualitative study of the dynamic performance due to an active power imbalance during a disturbance on the AC and DC sides of hybrid power systems with an emphasis on an MTDC interconnected offshore-onshore system. The widely used RoCoF (Rate of Change of Frequency) is adopted as a performance metric to assess the active power-frequency response from the perspective of the AC side. In addition, a modified quantification of the Rate of Change of Voltage (RoCoV), which is usually applied in the design of protection schemes, is suggested as an attempt to better capture the response of the DC voltage. The suitability of these metrics to properly reflect the resulting dynamics is analyzed by considering different disturbances, such as generator outages, line outages, converter outages, and faults like line-to-line and line-to-ground short-circuits, at either the AC or the DC sides. The different disturbances are executed using real-time digital simulations on the EMT model of the CIGRE BM1 DC-AC test system in RSCAD extsuperscript{ extregistered} FX. The performance metrics are well able to capture the impact of different disturbances on the response of the system. However, the performance metrics are not able to capture oscillating responses. A study on the parametric sensitivity of the control parameters in the outer control loop of the converters is executed to see the influence of these parameters on the dynamic response and whether the performance metrics are able to capture the influence. The parameters of the outer control loop determine the reference currents for the converter, and thus directly influence the output of the converters. The results show that, for a DC line-to-line short-circuit, the adjustment of the control parameters in the outer control loop has no influence on the response of the DC voltage. For each control setting, the DC voltage still immediately drops to 0. This is also reflected in the performance metrics. Whereas, adjusting the control parameters in the outer control loop influences the DC voltage response when subjected to an AC 3-lines-to-ground short-circuit. The proportional gains of the controllers mainly influence the overshoot of the DC voltage and have a small influence on the settling time. This corresponds to the role of the proportional gain in PI control, to respond quickly to faults. On the other hand, the integral gain responds slower and integrates the error over time to eliminate the residual error. Therefore, the results show that the integral gain mainly has an impact on the settling time of the response, and almost none on the overshoot. This is not captured by the calculated performance metrics. The performance metrics capture the response after the initial overshoot and this results in an unfair comparison between performance metrics.

With increasing healthcare demand, environmental concerns and waste management in healthcare, particularly in the operating room (OR), are significant issues. Disposable surgical energy devices, like vessel sealers, gain popularity in veterinary healthcare, but reusing them is officially forbidden by law and presents challenges. Objective: This research aims to clinically validate reprocessing the Ethicon HARMONIC® HD 1000i for safe reuse in veterinary healthcare. The study assesses the feasibility of using readily available disinfection methods and evaluates the device’s functionality and safety. The research’s scope is limited to a case study (functional analysis) on the Ethicon HARMONIC® HD 1000i. Methods: A comprehensive device analysis was performed using Hot Spot Mapping and Disassembly Map methods, followed by mechanical stability testing during sterilization conditions. A design update was proposed for easier disassembly. The functionality of 2x new, 2x reprocessed and 2x redesigned Ethicon HARMONIC® HD 1000i’s after reprocessing (disinfection, disassembly, reassembly, sterilization) was evaluated in a bench-top study. Tissue transsections on 120 cm pork fillets (6-11mm thickness) per device and pinch force measured with newly developed sensor (40 movements/device) were performed. Furthermore, 2 burst pressure measurements per device on frozen and embalmed artery sections were performed in collaboration with Amsterdam Skills Centre for Health Science. Results: In the disassembly analysis, 42 operations were needed, involving 40 parts and 10 steps with 6 tools. The disassembly time was 429 seconds (07:09 minutes) total. In tissue transsection, the new and reprocessed devices performed similarly, with mean task times ranging from 62.3 to 66.8 seconds. The redesigned devices had slower task times (averaging 196.1 seconds and 104.7 seconds) resulting in lower marching speeds (0.5-1.0 mm/s compared to 1.5-1.6 mm/s for new and reprocessed devices). In pinch force measurements the new devices performed best with average pinch forces of 19.1 N and 20.2 N. The reprocessed devices had slightly lower performance (16.8 N and 16.7 N), while the redesigned devices performed the worst with pinch forces of 5.6 N and 8.8 N, representing a significant drop in performance compared to the new devices. The burst pressure measurement tests showed that none of the devices were able to effectively seal the arteries, resulting in no pressure buildup. Discussion: Overall, reprocessed devices performed similarly to new devices in tissue transsection, showing the effectiveness of reprocessing. Achieved marching speeds by reprocessed and redesigned were considerable given tissue thickness differences, highlighting reprocessing’s potential to extend device lifespan. New devices had 15% higher pinch force than reprocessed, while redesigned had 63% lower force due to a weakened casing. Strengthening redesign and adding new jaw ends could improve modularity and power transmission. Burst pressure tests revealed all Ethicon Harmonic devices (new, reprocessed, redesigned) couldn’t effectively seal arteries, likely due to frozen artery characteristics and tissue alterations from embalming. Conclusion: This study emphasized the potential of modular medical devices with improved disassembly time, demonstrating that a modular design approach combined with reprocessing strategies holds promise to ensure a more sustainable healthcare system. This research is a collaboration between the Technical University of Delft, Johnson & Johnson Netherlands and GreenCycl. Keywords: ETHICON, harmonic, ENSEAL, Ligasure, ster- ilisation, reprocessing, medical instruments, healthcare, veterinary, redesign, modular, burst pressure, tissue transection, pinch force

Lely is developing a tethered manure applicator robot, designed to work on the fields of farms. This vehicle called the Jojo, is constrained in its movement due to the attached tether. It can not make tight turns and can only reverse by backtracking the driven path. This thesis explores the path planning issue and provides a novel solution. The problem is best described as the shortest path from a starting point to a set of strokes that cover the field, with a constrained turning radius. We first explore existing solutions and discover that none exist that are suitable. Further research finds that the behaviour of this vehicle is best compared with steerable needles, but at a different scale. First, we construct a simulation environment for the vehicle. This simulation is used to develop the plan execution engine, path follower and safety checks. This is necessary for testing the solutions in the simulation and in the real world. Secondly, with some inspiration from the solutions provided for the steerable needles, we arrive at a method for finding a Jojo path. The method makes use of a large graph that represents translations associated with a given location. We also provide methods for attaching the starting point and destinations in the form of strokes, either via the start or end of the strokes or via the middle. A Jojo plan is then obtained by performing a directed Steiner tree approximation on this graph, where the starting point is the root and the terminals are the strokes. In order to make the approach fast enough, we spend a substantial amount of time profiling and analysing the program and design a number of performance improvements. These allow for the approach to solve instances that are larger than necessary. Thirdly, we test, compare and improve the approach. We look at both small instances to perform numerical analysis in order to optimise a set of parameters. We then inspect larger instances that are based on real world scenarios. Lastly, we perform a set of real world tests using the vehicle. One of these tests highlights a shortcoming of the algorithm, which we discuss and provide a solution for

Using low-thrust propulsion for interplanetary space missions has the potential to allow for more payload for the same mass put into orbit compared to what impulsive propulsion would allow for. The disadvantages are found in mission planning, however, as the continuous nature of the thrust yields a more complex problem. One potential solution to help in the early planning and discovery phase of mission design is to employ artificial neural networks (ANNs). This has been done in the past, yet only in a limited capacity. Specifically, the engineering of the feature space used with the neural network has never been investigated. This thesis attempts to provide a first look at the influence of different feature space compositions. This includes the use of nine different state representations but also an analysis of additional values in the feature space. Additionally, the effect of extraneous variables, one of them notably being the target of interest, on the neural network performance is analyzed. The dataset used is generated using indirect optimization, and the case investigated is a set of minimum fuel Earth-Mars transfer trajectories. Low-thrust spacecraft trajectories are for space exploration what neural networks are for computer science: The vanguard of current trends with a lot of potential. Only recently have the two ideas, trajectory optimization and machine learning, been combined. In all the publications making use of machine learning for low-thrust optimization, a clear gap exists, however: Feature engineering has never been investigated. This thesis attempts to provide a first patch for that gap, limiting itself in scope to interplanetary Earth-Mars trajectories and feedforward neural networks. The data used as the basis to evaluate the performance of a number of factors having a potential influence on the choice of feature is obtained through indirect optimization. A novel method to generate those trajectories is implemented. The data is then used to investigate the effect different targets and network parameters have on the choice of features. On the feature side, a significant number of state representations are analyzed, both in dimensional and nondimensionalized form. Additionally, the feature space is expanded by additional variables, and various transformations are attempted. Over the course of this work, the importance of properly scaled data has been demonstrated. It is also shown that using Keplerian state and costate as feature and target, respectively, reliably yields good results. When mass is estimated, fuel mass is preferable over total spacecraft mass. Finally, none of the additional parameters or transformations (besides nondimensionalization) attempted resulted in reliable improvements and are thus best avoided.

Dehydration is a common medical condition in the elderly. This deficit in body water increases the risk of illnesses and mortality. The human body has no way of storing water which makes consistent water intake crucial. Water plays a multifaceted role, from being the medium for all bodily chemical reactions to regulating temperature and ensuring organ functionality. The challenges in the healthcare system emphasise the need for promoting independent ageing. With an increasing gap between the demand for caregivers and their availability, especially in countries like Germany, the healthcare system is on the brink of a crisis. The situation requires the development of solutions that empower the elderly to age independently, reducing the pressure on primary and secondary care systems. A significant observation is the decline in water intake with age. While younger generations have a variety of tools to monitor and motivate water intake, such products often overlook the elderly demographic. This thesis introduces "Daria", a product designed for hydration self-monitoring among the elderly. The primary stakeholder for this project is the elderly population, specifically those above 65 years who live outside care institutions. Context mapping was used to understand the elderly's daily routines and challenges related to fluid intake. Expert interviews provided insights into current medical practices and the nuances of hydration among the elderly. Functional prototyping was key in the design process, allowing for tangible testing and validation of design solutions. Literature research revealed several challenges the elderly face in maintaining optimal hydration levels. Ageing results in a reduced renal concentrating ability, diminishing the kidneys' capacity to retain water. More importantly, a decreased thirst sensation in older individuals often leads to inadequate fluid intake. Other factors, such as urinary incontinence and social isolation, further contribute to hydration difficulties. Various strategies have been explored to enhance hydration among older adults. While many interventions have been conducted in controlled environments like nursing homes, none have focused on home settings. Common strategies include verbal reminders to drink and providing a variety of beverages. In conclusion, "Daria" aims to introduce a new product category to enable hydration monitoring for the elderly. By understanding their unique challenges and habits, this product aspires to motivate them to maintain optimal hydration levels and enhance their overall quality of life.

Clouds play a crucial role in Earth’s systems, influencing the radiation budget and the hydrological cycle. However, their dynamics are poorly represented in climate models, leading to uncertainties in predicting global temperature changes. To better understand cloud dynamics and improve model parametrizations, the large-scale field campaign EUREC4A focused on studying cloud organization and its potential impact on climate feedback in the North Atlantic trade-wind region, where shallow marine cumulus clouds are prevalent. Within the EUREC4A framework, this study focuses on cloud fields and organization in the HARMONIE weather model to assess the impact of shallow convective parametrizations on its outputs. By comparing three experiments denominated as ’HARMONIE noHGTQS’, HARMONIE noHGTQS noSHAL’ and ’HARMONIE noHGTQS noUVmix’ one can identify discrepancies and determine what the impact of the various shallow convective parametrizations are. Several cloud organization metrics have been computed for the HARMONIE experiments as well as GOES-16 satellite snapshots. The results show that none of the experiments precisely capture the observed diurnal patterns successfully. There exist disparities in cloud cover, cloud quantity, cloud sizes, and the organization index. Removing shallow convective parametrization partly improves the representation of clouds. It exhibits a stronger correlation with the observed cloud cover data from ceilometer measurements and demonstrates a higher capability to replicate the amount of cloud entities seen in observations in comparison to the other experiments. Furthermore, disabling shallow convection leads to instability and deeper clouds. On the other hand momentum mixing alone has a small impact on clouds, yet it alters wind patterns, resulting in reduced speeds, and little production of precipitation. Overall the model struggles to reproduce detailed cloud patterns such as sugar, mainly due to its coarse resolution. However, it does exhibit a degree of day-to-day variability in cloud patterns. To gain a deeper understanding on the role of parametrized shallow convection, further investigation into model configurations, momentum mixing dynamics, and hybrid approaches are proposed.

The Port of Rotterdam is the biggest port in Europe and with its great location an important place for trade between Europe and other continents. Record numbers of intercepted illegal goods show that criminals use this port to traffic illegal goods. A lot is still unknown about the criminal supply chain in the Port of Rotterdam and about the chance to catch illegal goods that are smuggled. Therefore this research provides insights into this criminal supply chain by looking into the effects of the distribution of resources by law enforcement agencies between methods that can be used to catch illegal goods on the chance to catch illegal goods. This research looks at the criminal supply chain from South America to the Port of Rotterdam where it focuses on the smuggling methods used inside the Europe Container Terminals in the Port of Rotterdam. Criminals make use of four smuggling methods which are the pincode fraud method, the switch and pincode fraud method, the extraction method and the empty depot method. Law enforcement agencies have a scan and a surveillance method to catch illegal goods. The methods of law enforcement agencies can catch different smuggling methods and both have a chance to catch illegal goods smuggled with the empty depot method. Whereas criminals choose per illegal container which smuggling method will be used, this is not possible for law enforcement agencies. Therefore, a linear relationship between the part of resources appointed to a method and the accuracy of that method is assumed for the methods of law enforcement agencies. An agent-based model is built to capture the complexity of this criminal supply chain and show the behaviour of the cat-and-mouse-like situation between criminals and law enforcement agencies. This agent-based model is combined with the Nash equilibrium known from game theory, as game theory can give insights into this situation using a mathematical framework. As these research methods have not been combined for the distribution of resources among methods in the Port of Rotterdam in earlier research, this research provides insights into how these research methods can be combined and whether they will provide similar results. When combining the Nash equilibrium from game theory with the agent-based model it is expected that the distribution of resources for the two players, criminals and law enforcement agencies, in the agent-based model will eventually end up in or around the Nash equilibrium. This is because, in the Nash equilibrium, no player can get a higher expected payoff by deviating from the equilibrium. The players in the agent-based model update their distribution of resources every period of four weeks to adapt to the behaviour of the other player. This adaption is modelled with an updating rule. As literature indicated that the modelling of this updating rule can cause different behaviour in agent-based models, six different updating rules are tested in this research. Given a chance to catch illegal goods of the scan of 0.18 for smuggling methods that can be caught by the scan and a chance of 0.8 for surveillance for methods that can be caught by surveillance, the Nash equilibrium is reached when law enforcement agencies appoint 40/49 of their resources to the scan and 9/49 to surveillance and criminals appoint 40/49 of their resources to the pincode fraud method and 9/49 to the switch and pincode fraud method and the extraction method combined. In the Nash equilibrium criminals will not appoint any resources to the empty depot method. The six updating rules used in the agent-based model show different behaviours. Some updating rules cause the players in the agent-based model to appoint all their resources to only one method and others cause the players to end up in a cyclic pattern around the Nash equilibrium. The agent-based model also shows that by changing parameters of certain updating rules, the behaviour can change completely. For some updating rules the distribution of resources can get appointed according to an equilibrium which is not a Nash equilibrium as the payoffs of the methods are not equal to each other. Various difficulties arise when designing an updating rule. None of the six updating rules can guarantee the agent-based models to end up in or around the Nash equilibrium. These difficulties include that resources should be distributed according to the payoff of methods according to game theory and should not be done according to the success rate of methods. Other difficulties arise when methods get appointed little or no resources. As it is the best response for players to distribute all their resources to one method when the other player is not playing according to the Nash equilibrium, the updating rule needs to be able to appoint zero resources to a method. Updating rules should also ensure that this method can be reappointed more resources when the other player changes its distribution of resources. Other difficulties include equilibria that are not a Nash equilibrium as mentioned above and the fact that players do not adapt in the same way when they do not have the same number of methods. From this research, it can be concluded that in order to use an agent-based model for the situation between law enforcement agencies and criminals the knowledge about Nash equilibria should be considered while creating the model. This will not happen automatically as seen by the multiple difficulties this research showed. This research also shows that updating the distribution of resources by law enforcement agencies is important as they risk having an unnecessarily low chance to catch illegal goods when criminals adapt, while law enforcement agencies would not. Therefore, it is recommended for law enforcement agencies to update the distribution of resources when it is expected that criminals will adapt as well, to not risk having an unnecessarily low chance of catching illegal goods. Furthermore, it is recommended to consider the Nash equilibrium while updating the distribution of resources and to carefully observe the distribution of resources of criminals when appointing all resources to only one method. Limitations of this research include that there are only a limited number of methods included and players can not learn new methods. Due to the limited data about the criminal supply chain and about the methods that can be used by law enforcement agencies, there is deep uncertainty in model parameters, especially in the chances of catching illegal goods of the methods of law enforcement agencies. Therefore the results are not entirely valid and should only be used to analyse expected behaviour. Further research is needed on these chances of catching illegal goods and to test more updating rules as this research does not provide an updating rule that will ensure that an agent-based model will always end up in or around the Nash equilibrium.

You will be reading a comprehensive study that examines the shortage of instruments for performing surgery in sub-Saharan Africa and the wastage of quality surgical instruments in the Netherlands. The report explores the potential solution of repositioning the excess instruments to sub-Saharan Africa, focusing on three product categories identified by Unifix Care as having the potential to make an impact. The thesis investigates the important elements that determine the value of these second-life products in Kenya. The conclusion reached is that none of the three product categories will have a significant impact in Kenya, leading to the recommendation for Unifix Care to discontinue this proposition. In the next part of the thesis, the report takes a higher-level perspective and examines the decision-making process of Unifix Care when approaching and investigating expansion opportunities. It highlights the limitations of the current approach, which is deemed non-strategic and unsustainable in the long term. The section discusses the significance of making structured decisions and proposes a suggestion to proactively predict market potential to avoid investing time and resources into unprofitable opportunities. A recommendation is proposed to prevent this by implementing a quickscan that forecasts market conditions in advance. This approach aims to stay focused on the most important activities. Moreover, this thesis promotes the application of an effectual approach in conjunction with proactive prediction methodologies and theories that align with the causation paradigm. This project delivers: A study on the adoption of excessive Western second-life surgical instruments in Kenya, analyzing the potential impact by means of a triple constraint analysis. A recommendation for Unifix Care to enhance decision-making effectiveness and adopt a more strategic approach for future opportunities. A decision support model that facilitates strategic decision-making for Unifix Care. A strategic opportunity framework that aids Unifix Care in prioritizing its actions based on opportunity landscapes.

Network Intrusion Detection Systems (NIDSs) defend our computer networks against malicious network attacks. Anomaly-based NIDSs use machine learning classifiers to categorise incoming traffic. Research has shown that classifiers are vulnerable to adversarial examples, perturbed inputs that lead the classifier into misclassifying the input. Existing work has shown weaknesses in classifiers for classifying network traffic, but none have shown the possibility of automatically recreating network attacks that can bypass existing anomaly-based NIDSs. Regular methods for generating black-box adversarial examples create packets that are invalid. We present AGONI, a Multi-Objective Genetic Algorithm for generating network packets that are both valid packets and adversarial examples for NIDSs. AGONI can successfully generate valid adversarial examples in multiple attack scenarios. Against the NIDS Suricata, 99.93% of the generated adversarial examples can successfully bypass the defence. We compare the performance of AGONI against randomly generating network packets, the Boundary Attack and an adjusted version of the Boundary Attack which can better create valid adversarial examples. Only AGONI consistently generates valid adversarial examples when compared to the Random Attack (82%), the Boundary Attack (0%) and the Networking Boundary Attack (74%).