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CSEE Journal of Power and Energy Systems 2024年第1期10卷 427-431页

作者： Chao Ren Han Yu Yan Xu Zhao Yang Dong School of Computer Science and Engineering Nanyang Technological UniversitySingapore School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore

This letter proposes a reliable transfer learning(RTL)method for pre-fault dynamic security assessment(DSA)in power systems to improve DSA performance in the presence of potentially related unknown *** takes individual discrepancies into consideration and can handle unknown faults with incomplete *** experiment results demonstrate high DSA accuracy and computational efficiency of the proposed RTL *** analysis shows RTL can guarantee system performance.

关键词： Adversarial training dynamic security assessment maximum classifier discrepancy missing data transfer learning

Visible Light Indoor Positioning System Based on Pisarenko Harmonic Decomposition and Neural Network

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Chinese Journal of Electronics 2024年第1期33卷 195-203页

作者： Li ZHAO Yi REN Qi WANG Lange DENG Feng ZHANG School of Electronic Information Engineering Xi’an Technological University

Visible-light indoor positioning is a new generation of positioning technology that can be integrated into smart lighting and optical communications. The current received signal strength(RSS)-based visible-light positioning systems struggle to overcome the interferences of background and indoor-reflected noise. Meanwhile, when ensuring the lighting, it is impossible to use the superposition of each light source to accurately distinguish light source information; furthermore, it is difficult to achieve accurate positioning in complex indoor environments. This study proposes an indoor positioning method based on a combination of power spectral density detection and a neural network. The system integrates the mechanism for visible-light radiation detection with RSS theory, to build a back propagation neural network model fitting for multiple reflection channels. Different frequency signals are loaded to different light sources at the beacon end, and the characteristic frequency and power vectors are obtained at the location end using the Pisarenko harmonic decomposition method. Then, a complete fingerprint database is established to train the neural network model and conduct location tests. Finally, the location effectiveness of the proposed algorithm is verified via actual positioning experiments. The simulation results show that, when four groups of sinusoidal waves with different frequencies are superimposed with white noise, the maximum frequency error is 0.104 Hz and the maximum power error is 0.0362 W. For the measured positioning stage, a 0.8 m × 0.8 m × 0.8 m solid wood stereoscopic positioning model is constructed, and the average error is 4.28 cm. This study provides an effective method for separating multi-source signal energies, overcoming background noise, and improving indoor visible-light positioning accuracies.

关键词： Neural networks Measurement uncertainty Position measurement Harmonic analysis Light emitting diodes Frequency estimation Indoor positioning systems

Tuning heterogeneous microstructures to enhance mechanical properties of nano-TiN particle reinforced Haynes 230 composites by laser powder bed fusion

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Rare Metals 2024年第9期43卷 4548-4565页

作者： Wen-Jie Liu Hui Li Qian-Xing Yin He-Jun Du School of Power and Mechanical Engineering Wuhan University The Institute of technological Sciences Wuhan University School of Mechanical&Aerospace Engineering Nanyang Technological University

Laser powder bed fusion(LPBF) is considered to be one of the most promising additive manufacturing technologies for producing components with geometries and high geometrical precision that are unattainable by traditional technologies. The superalloy exhibits exceptional mechanical and high-temperature performances,rendering it a prime candidate for advanced aero-engine applications. Despite the high demand for LPBF-manufactured superalloys, the superalloy is one of the materials manufactured difficultly by LPBF due to their large laser absorptivity fluctuation, poor molten pool stability and sharp temperature gradient. Hence, superalloys are characterized by severe pores, undesirable coarse columnar grains and poor mechanical properties. In this work, the effect of nano-Ti N particles on defects, molten pool characteristics and microstructure and performance of the composites were investigated. The 4.5 wt% Ti N/Haynes230 samples exhibited exceptional nanohardness and elastic modulus with maximum values reaching 5.53 GPa and 240.03 GPa, respectively. These superior mechanical properties were attributed to the combined effects of spatter and gas pore inhibition, grain refinement and duplex nanophases strengthening. Moreover, the stability of molten pool was enhanced, and spatter was effectively suppressed by adding nano-Ti N particles, while grain refinement and columnar to equiaxed transitions were promoted. Furthermore, the matrix exhibited a high dislocation density due to a significant hindrance of dislocation movement caused by massive nano-phases(e.g., Ti N and M23C6), resulting in the formation of extensive dislocation tangles and *** work offers novel insights into the role of nanoparticles reinforced superalloy composites by LPBF.

关键词： Composites Laser powder bed fusion Mechanical properties Microstructure Molten pool characteristics

Distributed Fault-Tolerant Control of Uncertain Multi-Agent Systems with Connectivity Maintenance

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Journal of Systems Science & Complexity 2024年第1期37卷 40-62页

作者： XING Xueyan HU Guoqiang Continental-NTU Corporate Lab Nanyang Technological UniversitySingapore 639798Singapore Continental-NTU Corporate Lab and the School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore 639798Singapore

In this paper,a distributed cooperative control protocol is presented to deal with actuator failures of multi-agent systems in the presence of connectivity *** the developed strategy,each agent can track the reference trajectory of the leader in the presence of actuator failures,disturbances and *** connectivity of the multi-agent system can always be ensured during the control *** achieve the aforementioned control objectives,a potential function is introduced to the distributed adaptive fault-tolerant control algorithm to preserve the initial connected network among the *** uncertainty of the multi-agent system,which is allowed to be described by discontinuous functions,is approximated and compensated using the fuzzy logic *** asymptotic stability of the closed-loop system is demonstrated through the use of Cellina’s approximate selection theorem of nonsmooth *** to the developed adaptive laws,the upper bound of the disturbance is allowed to be uncertain,which facilitates the implementation of the control ***,simulation results are provided to verify the effectiveness of the proposed control scheme.

关键词： Actuator failure connectivity maintenance coordination control uncertainties

A Cocktail of Natural Compounds Holds Promise for New Immunotherapeutic Potential in Head and Neck Cancer

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Chinese Journal of Integrative Medicine 2024年第1期30卷 42-51页

作者： Sunil Kumar Asmita Das Department of Biotechnology Delhi Technological UniversityDelhi(110042)India

Objective: To obtain detailed understanding on the gene regulation of natural compounds in altering prognosis of head and neck squamous cell carcinomas(HNSC). Methods: Gene expression data of HNSC samples and peripheral blood mononuclear cells(PBMCs) of HNSC patients were collected from Gene Expression Omnibus(GEO). Differential gene expression analysis of GEO datasets were achieved by the GEO2R tool. Common differentially expressed gerres(DEGs) were screened by comparing DEGs of HNSC with those of PBMCs. The combination was further analyzed for regulating pathways and biological processes that were affected. Results: Totally 110 DEGs were retrieved and identified to be involved in biological processes related to tumor regulation. Then 102 natural compounds were screened for a combination such that the expressions of all 110 commonly DEGs were altered. A combination of salidroside, ginsenoside Rd, oridonin, britanin, and scutellarein was chosen. A multifaceted, multi-dimensional tumor regression was showed by altering autophagy, apoptosis, inhibiting cell proliferation, angiogenesis, metastasis and inflammatory cytokines production. Conclusions: This study has helped develop a unique combination of natural compounds that will markedly reduce the propensity of development of drug resistance in tumors and immune evasion by tumors. The result is crucial to developing a combinatorial natural therapeutic cocktail with accentuated immunotherapeutic potential.

关键词： natural compounds chemopreventive gene expression head and neck cancer immunomodulator salidroside ginsenoside Rd oridonin britanin scutellarein

Optimal Coordination of Transportable Power Sources and Repair Crews for Service Restoration of Distribution Networks Considering Uncertainty of Traffic Congestion

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 189-201页

作者： Zhao Shi Yan Xu Dunjian Xie Shiwei Xie Amer M.Y.M.Ghias Nanyang technological university Singapore the School of Electrical Engineering and Automation Fuzhou UniversityFuzhou 350108China

This paper proposes a new method for service restoration of distribution network with the support of transportable power sources(TPSs)and repair crews(RCs).Firstly,a coupling model of distribution networks and vehicle routing of TPSs and RCs is proposed,where the TPSs serve as emergency power supply sources,and the RCs are used to repair the faulted *** the uncertainty of traffic congestion,the probability distribution of the travel time spent on each road is derived based on the Nesterov user equilibrium model,and a two-stage stochastic program is formulated to determine the optimal routings of TPSs and *** efficiently solve the proposed stochastic mixed-integer linear program(MILP),a two-phase scenario reduction method is then developed to scale down the problem size,and an adaptive progressive hedging algorithm is used for an efficient *** effectiveness of the proposed methods and algorithms has been illustrated in a modified IEEE 33-bus system.

关键词： Service restoration distribution network traffic uncertainty transportable power source repair crew stochastic program

Direct recycling of Li-ion batteries from cell to pack level:Challenges and prospects on technology,scalability,sustainability,and economics

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Carbon Energy 2024年第6期6卷 1-39页

作者： Joseph Jegan Roy Do Minh Phuong Vivek Verma Richa Chaudhary Michael Carboni Daniel Meyer Bin Cao Madhavi Srinivasan Energy Research Institute@NTU(ERI@N) SCARCE LaboratoryNanyang Technological UniversitySingaporeSingapore School of Materials Science and Engineering Nanyang Technological UniversitySingaporeSingapore CEA CNRSENSCMUniversity of MontpellierUMR 5257(ICSM)Bagnols-sur-Cèze CedexFrance School of Civil and Environmental Engineering Nanyang Technological UniversitySingaporeSingapore

Direct recycling is a novel approach to overcoming the drawbacks of conventional lithium-ion battery(LIB)recycling processes and has gained considerable attention from the academic and industrial sectors in recent *** primary objective of directly recycling LIBs is to efficiently recover and restore the active electrode materials and other components in the solid phase while retaining electrochemical *** technology's advantages over traditional pyrometallurgy and hydrometallurgy are costeffectiveness,energy efficiency,and sustainability,and it preserves the material structure and morphology and can shorten the overall recycling *** review extensively discusses the advancements in the direct recycling of LIBs,including battery sorting,pretreatment processes,separation of cathode and anode materials,and regeneration and quality enhancement of electrode *** encompasses various approaches to successfully regenerate high-value electrode materials and streamlining the recovery process without compromising their electrochemical ***,we highlight key challenges in direct recycling when scaled from lab to industries in four perspectives:(1)battery design,(2)disassembling,(3)electrode delamination,and(4)commercialization and *** on these challenges and changing market trends,a few strategies are discussed to aid direct recycling efforts,such as binders,electrolyte selection,and alternative battery designs;and recent transitions and technological advancements in the battery industry are presented.

关键词： battery design cathode regeneration direct recycling graphite recycling lithium-ion battery,scaling-up

Heterogeneous integration of 2D materials on Si charge-coupled devices as optical memory

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Science China(Information Sciences) 2024年第6期67卷 190-197页

作者： Zheng BIAN Feng TIAN Zongwen LI Xiangwei SU Tianjiao ZHANG Jialei MIAO Bin YU Yang XU Yuda ZHAO College of Integrated Circuits Hangzhou Global Scientific and Technological Innovation CentreZhejiang University

Optical memory integrates the function of optical sensing in memory devices, remarkably promoting the interconnection between sensory and memory terminals. Silicon charge-coupled photodetectors and floating gate memory have been widely used in imaging and storage technologies, respectively. However,the heterogeneous integration of the two devices requires technological innovation and complex electrical connections. In this work, we adopt a three-dimensional layer stacking method to design a novel optical memory device. On the top of Si charge-coupled photodetectors, we successively deposit two-dimensional graphene,hexagonal boron nitride, and molybdenum disulfide as a floating gate layer, a tunneling layer, and a readout layer, respectively. By applying a gate bias on lightly doped Si, a deep depletion layer is formed with a high voltage potential drop. Under dark conditions, the depletion layer cannot be filled, and the electric field across the h-BN tunnel barrier is relatively small. Under light irradiation, the deep depletion layer is gradually filled, and the h-BN tunneling layer withstands the increasing electric field, resulting in charge storage in the floating gate layer. Based on this mechanism, the device exhibits a gate voltage-dependent operation mode, including an integrated optical sensing-memory mode and an electrically driven storage mode. Under moderate gate voltage, the device can effectively detect the optical information with varied intensity and store the optical information in the floating gate, displaying optically controlled memory characteristics. Our work demonstrates a compact device structure for optical memory and displays excellent optically controlled memory performance, which can be applied in artificial vision systems.

关键词： heterogeneous integration charge-coupled device floating gate optical memory molybdenum disulfide lightly doped silicon

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Design of Robust Var Reserve Contract for Enhancing Reactive Power Ancillary Service Market Efficiency

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 767-771页

作者： Yunyang Zou Yan Xu School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore 639798Singapore

In a deregulated Var market, market power issue is more serious than in an energy market since reactive power cannot be transmitted over long distances. This letter designs a multi-timescale Var market framework, where market power that may arise in the hourly-ahead Var support service market due to system configuration deficiency and market structure flaws can be eliminated by day-ahead contract-based Var reserve service market. Settlement of day-ahead Var reserve contract is formulated as a two-stage robust optimization (TSRO) model considering worst case of uncertainty realization and potential market power that may arise in hourly-ahead market. TSRO with integer recourses is then solved by a new column and constraint generation algorithm. Results show a robust Var reserve contract can fully eliminate market power, and prevent suppliers from manipulating market prices.

关键词： Market efficiency market power reactive power ancillary service two-stage robust optimization Var reserve

Toward Trustworthy Decision-Making for Autonomous Vehicles:A Robust Reinforcement Learning Approach with Safety Guarantees

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Engineering 2024年第2期33卷 77-89页

作者： Xiangkun He Wenhui Huang Chen Lv School of Mechanical and Aerospace Engineering Nanyang Technological UniversitySingapore 639798Singapore

While autonomous vehicles are vital components of intelligent transportation systems,ensuring the trustworthiness of decision-making remains a substantial challenge in realizing autonomous ***,we present a novel robust reinforcement learning approach with safety guarantees to attain trustworthy decision-making for autonomous *** proposed technique ensures decision trustworthiness in terms of policy robustness and collision ***,an adversary model is learned online to simulate the worst-case uncertainty by approximating the optimal adversarial perturbations on the observed states and environmental *** addition,an adversarial robust actor-critic algorithm is developed to enable the agent to learn robust policies against perturbations in observations and ***,we devise a safety mask to guarantee the collision safety of the autonomous driving agent during both the training and testing processes using an interpretable knowledge model known as the Responsibility-Sensitive Safety ***,the proposed approach is evaluated through both simulations and *** results indicate that the autonomous driving agent can make trustworthy decisions and drastically reduce the number of collisions through robust safety policies.

关键词： Autonomous vehicle Decision-making Reinforcement learning Adversarial attack Safety guarantee