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Synchronization of power systems under stochastic disturbances

Wang, Zhen (author), Xi, Kaihua (author), Cheng, Aijie (author), Lin, H.X. (author), Ran, André C.M. (author), van Schuppen, J.H. (author), Zhang, Chenghui (author)

The synchronization of power generators is an important condition for the proper functioning of a power system, in which the fluctuations in frequency and the phase angle differences between the generators are sufficiently small when subjected to stochastic disturbances. Serious fluctuations can prompt desynchronization, which may lead to...

journal article 2023

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Combined CNN and RNN Neural Networks for GPR Detection of Railway Subgrade Diseases

Liu, Huan (author), Wang, Shilei (author), Jing, Guoqing (author), Yu, Ziye (author), Yang, Jin (author), Zhang, Yong (author), Guo, Y. (author)

Vehicle-mounted ground-penetrating radar (GPR) has been used to non-destructively inspect and evaluate railway subgrade conditions. However, existing GPR data processing and interpretation methods mostly rely on time-consuming manual interpretation, and limited studies have applied machine learning methods. GPR data are complex, high...

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Enhancing thermal degradation stability of BaSi₂O₂N₂:Eu²⁺ for white light-emitting diodes by ultra-thin Al₂O₃ layer via atomic layer deposition

Zhao, Y. (author), Wang, Xiao (author), Li, Quan an (author), Zhang, Xinyu (author), Li, Ye (author), Xie, Rong Jun (author), van Ommen, J.R. (author), Hintzen, H.T.J.M. (author)

The cyan-emitting BaSi₂O₂N₂:Eu²⁺ phosphor is a promising narrow-band and high-efficiency luminescent material used in wide-color-gamut white light-emitting diodes (wLEDs). However, its serious degradation under thermal attacks hinders its practical applications and needs to be improved. Herein, we...

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基于分段步进式弹塑性格构模型的混凝土破坏过程细观模拟

Zhang, H. (author), Jin, Zuquan (author), Jiang, Nengdong (author), Ge, Zhi (author), Schlangen, E. (author), Ling, Yifeng (author), Šavija, B. (author), Wang, Zheng (author)

The classically lattice model assumes the local elements behave elastic brittle, neglecting the ductility of the mortar matrix. This leads to the simulated load⁃displacement response more brittle than the realistic. To solve the aforementioned issue, a piece⁃wise approach was introduced to describe the elastic⁃plastic constitutive relation of...

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Asymmetric Sites on the ZnZrO_x Catalyst for Promoting Formate Formation and Transformation in CO₂ Hydrogenation

Feng, Zhendong (author), Tang, Chizhou (author), Zhang, Pengfei (author), Li, Kun (author), Li, G. (author), Wang, Jijie (author), Feng, Zhaochi (author), Li, Can (author)

The role of formate species for CO₂ hydrogenation is still under debate. Although formate has been frequently observed and commonly proposed as the possible intermediate, there is no definite evidence for the reaction of formate species for methanol production. Here, formate formation and conversion over the ZnZrO_x solid...

journal article 2023

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Reverse Recovery Optimization of Multiepi Superjunction MOSFET Based on Tunable Doping Profile

Liu, Ke (author), Tan, C. (author), Li, Shizhen (author), Yuan, Wucheng (author), Liu, X. (author), Zhang, Kouchi (author), French, P.J. (author), Ye, H. (author), Wang, S. (author)

This paper proposes and simulates research on the reverse recovery characteristics of two novel superjunction (SJ) MOSFETs by adjusting the doping profile. In the manufacturing process of the SJ MOSFET using multilayer epitaxial deposition (MED), the position and concentration of each Boron bubble can be adjusted by designing different doping...

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Selective Peroxygenase-Catalysed Oxidation of Toluene Derivates to Benzaldehydes

Wang, Y. (author), Teetz, Niklas (author), Holtmann, Dirk (author), Alcalde, Miguel (author), van Hengst, J.M.A. (author), Liu, Xiaoxiao (author), Wang, Mengfan (author), Qi, Wei (author), Zhang, Wuyuan (author), Hollmann, F. (author)

Biocatalytic oxidation reactions of toluene derivates to the corresponding aldehydes are typically challenged by regio- and chemoselectivity issues. In this contribution we address both challenges by a combined reactant- and reaction engineering approach. We demonstrate that the peroxygenase-catalysed transformation of ring-substituted...

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Stretchable strain sensor based on HfSe₂/LIG composite with high sensitivity and good linearity within a wide range

Yang, Huiru (author), Wang, S. (author), Huang, Qianming (author), Tan, C. (author), Gao, Chenshan (author), Xu, Siyuan (author), Ye, Huaiyu (author), Zhang, Kouchi (author)

Flexible strain sensors based on nanomaterials have sparked a lot of interest in the field of wearable smart electronics. Laser induced graphene (LIG) based sensors in particular stand out due to their straightforward fabrication procedure, three-dimensional porous structures, and exceptional electromechanical capabilities. Recent studies...

journal article 2023

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Rank classification method for cascade reservoirs considering scale, benefits, and risk consequences

Wang, Te (author), Li, Zongkun (author), Ge, W. (author), Zhang, Yadong (author), Jiao, Yutie (author), Jing, Laihong (author), van Gelder, P.H.A.J.M. (author)

Cascade reservoirs are essential in water resource utilization, flood control, and disaster mitigation. They have been built in several rivers worldwide. The rank classification for cascade reservoirs has significant practical implications for resource distribution decisions and risk management strategies and is also essential for ensuring the...

journal article 2023

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Laser-Induced Graphene Formation on Chitosan Derivatives toward Ecofriendly Electronics

Huang, Qian Ming (author), Yang, Huiru (author), Wang, S. (author), Liu, X. (author), Tan, C. (author), Luo, Anxin (author), Xu, Siyuan (author), Zhang, Kouchi (author), Ye, H. (author)

Laser-induced graphene (LIG) has aroused a wide range of research interests ranging from micro-nano energy devices to the Internet of Things (IoT). Nevertheless, the non-degradability of most-used synthetic polymer carbon sources poses a serious threat to the environment. In this work, ecofriendly chitosan-based derivatives, including...

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Rapid Fabrication of High-Performance Flexible Pressure Sensors Using Laser Pyrolysis Direct Writing

Wang, S. (author), Zong, Qihang (author), Yang, Huiru (author), Tan, C. (author), Huang, Qianming (author), Liu, X. (author), Zhang, Kouchi (author), French, P.J. (author), Ye, H. (author)

The fabrication of flexible pressure sensors with low cost, high scalability, and easy fabrication is an essential driving force in developing flexible electronics, especially for high-performance sensors that require precise surface microstructures. However, optimizing complex fabrication processes and expensive microfabrication methods...

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Effect of epoxy resin addition on properties and corrosion behavior of sintered joints in power modules serviced offshore

Wang, Xinyue (author), Yang, Zhoudong (author), Wang, Boya (author), Chen, Wei (author), Zhang, Kouchi (author), Zhang, Jing (author), Fan, J. (author), Liu, P. (author)

Power modules applied in offshore applications are facing risks of corrosion failures on die-attach materials due to high humidity and H₂S exposure. To investigate such corrosion behavior for sintered die-attach materials, we conducted a study with four groups of samples fabricated using copper and silver metal particles under...

journal article 2023

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Synchronization of Coupled Phase Oscillators with Stochastic Disturbances and the Cycle Space of the Graph

Xi, Kaihua (author), Wang, Zhen (author), Cheng, Aijie (author), Lin, H.X. (author), van Schuppen, J.H. (author), Zhang, Chenghui (author)

The synchronization stability of a complex network system of coupled phase oscillators is discussed. In case the network is affected by disturbances, a stochastic linearized system of the coupled phase oscillators may be used to determine the fluctuations of phase differences in the lines between the nodes and to identify the vulnerable lines...

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Solvent modulation, microstructure evaluation, process optimization, and nanoindentation analysis of micro-Cu@Ag core–shell sintering paste for power electronics packaging

Chen, Haixue (author), Wang, Xinyue (author), Zeng, Zejun (author), Zhang, Kouchi (author), Zhang, Jing (author), Liu, Pan (author)

With the development of electronic technology towards high power, miniaturization, and system integration, power electronic packaging is facing increasing challenges, especially for die attachment. This research aims to explore silver-coated copper (Cu@Ag) paste with sufficient mechanical properties and high-temperature reliability, as an...

journal article 2023

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A non-unit line protection method for MMC-HVDC grids based on the curvatures of backward traveling waves

Xie, F. (author), Hao, Zhiguo (author), Ye, Dongmeng (author), Yang, Songhao (author), Li, Chuanxi (author), Dai, Guoan (author), Zhang, Baohui (author), Wang, Ting (author)

The existing protection techniques for high-voltage direct-current (HVDC) grids suffer from several shortcomings such as high sampling frequency, poor robustness, and reliance on simulation for threshold setting. To solve these problems, this paper proposes a non-unit protection method for modular multilevel converter (MMC)-based HVDC grids...

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High-resolution imaging of two radio quasars at the end of the reionization epoch

Perger, Krisztina (author), Zhang, Yingkang (author), Frey, Sándor (author), An, Tao (author), Gabányi, Krisztina E. (author), Gurvits, L. (author), Hwang, Chorng Yuan (author), Koptelova, Ekaterina (author), Paragi, Zsolt (author), Wang, Ailing (author)

There are approximately 250 quasars discovered at redshift z ≥ 6, of which only a handful were detected in radio bands, and even fewer were imaged with the highest resolution very long baseline interferometry (VLBI) technique. Here we report the results of our dual-frequency observations with the Very Long Baseline Array (VLBA) of two such...

journal article 2023

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Deep Bayesian survival analysis of rail useful lifetime

Zeng, Cheng (author), Huang, Jinsong (author), Wang, H. (author), Xie, Jiawei (author), Zhang, Yuting (author)

Reliable estimation of rail useful lifetime can provide valuable information for predictive maintenance in railway systems. However, in most cases, lifetime data is incomplete because not all pieces of rail experience failure by the end of the study horizon, a problem known as censoring. Ignoring or otherwise mistreating the censored cases...

journal article 2023

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A coupled MPM-DEM method for modelling soil-rock mixtures

Li, Jianguo (author), Wang, Bin (author), Wang, Di (author), Zhang, Pei (author), Vardon, P.J. (author)

Aiming at modelling the mechanical behaviour of soil-rock mixtures accurately and efficiently, a coupled MPM-DEM formulation combining the material point method (MPM) and the discrete element method (DEM) is proposed. It is solved concurrently via the contact force linking the two individual methods. Specifically, the soil is modelled with...

journal article 2023

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Performance Comparison between Data Centers with Different Airflow Management Technologies

Li, Xueqiang (author), Zhang, Zhongyao (author), Wang, Qihui (author), Yang, Xiaohu (author), Hooman, K. (author), Liu, Shengchun (author)

Air cooling systems are widely used in current data centers owing to their low capital costs and high reliability. To satisfy the increasing rack power density, the optimal air-cooling technology and an economic analysis should be carefully discussed. Therefore, this study discusses four airflow management technologies: Case 1: raised floor...

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The FluidFlower Validation Benchmark Study for the Storage of CO ₂

Flemisch, Bernd (author), Nordbotten, Jan M. (author), Geiger, S. (author), Hajibeygi, H. (author), Tian, X. (author), Voskov, D.V. (author), Wang, Y. (author), Wapperom, M.B. (author), Zhang, Z. (author)

Successful deployment of geological carbon storage (GCS) requires an extensive use of reservoir simulators for screening, ranking and optimization of storage sites. However, the time scales of GCS are such that no sufficient long-term data is available yet to validate the simulators against. As a consequence, there is currently no solid basis...

journal article 2023