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Noninvasive beam diagnosis based on the TM_(010)mode

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Nuclear Science and Techniques 2024年第7期35卷 115-125页

作者： Chuang-Ye Song Wen-hui Huang Department of Engineering Physics Tsinghua University BeijingBeijing100084China of Education Beijing100084China

A resonant cavity based on the TM_(010)mode is an effective tool for noninvasive beam characterization. This technique has the advantages of a high signal-to-noise ratio, compact structure, and is related to multiple parameters compared with other beam monitors. In this study, high-precision measurements of the bunch charge, arrival time, bunch length, and energy parameters based on the TM_(010)mode are discussed. A cavity beam arrival time monitor(BAM) utilizing a phase cavity has been widely used in many facilities. Regarding bunch-length measurements, the influence of the beam energy, beam offset,and longitudinal spectrum on the TM_(010)mode are carefully considered to reduce errors, and the theoretical resolution of two cavities with different frequencies is analyzed. Owing to the dependence of the beam velocity of the beam loss factor, this method can also be used for the detection low beam energy using two cavities with the same frequency but different cavity lengths. A set of three cavities with different lengths and frequencies of 1.902 and 11.424 GHz is presented for measuring the four aforementioned parameters.

关键词： TM_(010)mode Noninvasive diagnosis Beam length Low energy

Vibration Suppression for Active Magnetic Bearings Using Adaptive Filter with Iterative Search Algorithm

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CES Transactions on Electrical Machines and Systems 2024年第1期8卷 61-71页

作者： Jin-hui Ye Dan Shi Yue-Sheng Qi Jin-hui Gao Jian-Xin Shen IEEE Department of Electrical Engineering Zhejiang UniversityHangzhou 310027China CES and IEEE

Active Magnetic Bearing(AMB) is a kind of electromagnetic support that makes the rotor movement frictionless and can suppress rotor vibration by controlling the magnetic force. The most common approach to restrain the rotor vibration in AMBs is to adopt a notch filter or adaptive filter in the AMB controller. However, these methods cannot obtain the precise amplitude and phase of the compensation current. Thus, they are not so effective in terms of suppressing the vibrations of the fundamental and other harmonic orders over the whole speed range. To improve the vibration suppression performance of AMBs,an adaptive filter based on Least Mean Square(LMS) is applied to extract the vibration signals from the rotor displacement signal. An Iterative Search Algorithm(ISA) is proposed in this paper to obtain the corresponding relationship between the compensation current and vibration signals. The ISA is responsible for searching the compensating amplitude and shifting phase online for the LMS filter, enabling the AMB controller to generate the corresponding compensation force for vibration suppression. The results of ISA are recorded to suppress vibration using the Look-Up Table(LUT) in variable speed range. Comprehensive simulations and experimental validations are carried out in fixed and variable speed range, and the results demonstrate that by employing the ISA, vibrations of the fundamental and other harmonic orders are suppressed effectively.

关键词： Active Magnetic Bearing(AMB) Adaptive filter Iterative search algorithm Least mean square(LMS) Vibration suppression

Blockchain-based engine data trustworthy swarm learning management method

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Blockchain(Research and Applications) 2024年第2期5卷 73-85页

作者： Zhenjie Luo hui Zhang School of Cybersecurity Northwestern Polytechnical University Xi’an 710072China

Engine data management is of great significance for ensuring data security and sharing,as well as facilitating multi-party collaborative *** data management approaches often involve decentralized data storage that is vulnerable to tampering,making it challenging to conduct multi-party collaborative learning under privacy protection conditions and fully leverage the value of ***,data with compromised integrity can lead to incorrect results if used for model ***,this paper aims to break down data sharing barriers and fully utilize decentralized data for multi-party collaborative learning under privacy protection *** propose a trustworthy engine data management method based on blockchain technology to ensure data immutability and *** address the issue of limited data samples for some users resulting in poor model performance,we introduce swarm learning techniques based on centralized machine learning and design a trustworthy data management method for swarm learning,achieving trustworthy regulation of the entire *** conduct research on engine models under swarm learning based on the NASA open dataset,effectively organizing decentralized data samples for collaborative training while ensuring data privacy and fully leveraging the value of data.

关键词： Engine Data integrity Data management Blockchain Swarm learning

Optical and electrical anisotropy regulation engineering of low-dimensional materials toward polarized detection and imaging applications

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Rare Metals 2024年第7期43卷 2968-2993页

作者： Jian-Bin Zhang Nan Zhou Li-hui Zhang Cong-hui Shang Jia-Xuan Li Yi Zhao Guo-hui Jia Ru-Sen Yang Hua Xu Xiao-Bo Li Shaanxi Joint Key Laboratory of Graphene Shaanxi Key Laboratory of High-Orbits-Electron Materials and Protection Technology for AerospaceShaanxi Joint Key Laboratory of GrapheneSchool of Advanced Materials and NanotechnologyXidian UniversityXi'an710126China Guangzhou Institute of Technology Xidian UniversityGuangzhou 710068China Xi'an Thermal Power Research Institute Co. LtdXi'an 710054China Key Laboratory of Applied Surface and Colloid Chemistry Ministry of EducationShaanxi Key Laboratory for Advanced Energy DevicesShaanxi Engineering Lab for Advanced Energy TechnologySchool of Materials Science and EngineeringShaanxi Normal UniversityXi'an Xi'an 710119China

Polarized-sensitive image sensors are a kind of photodetector with great development potential due to their enhanced ability to detect and identify the target objects from the aspect of spatial,spectral and polarized ***,low-dimensional anisotropic materials with inherent anisotropic properties,ultrathin thickness,tunable bandgap and feasible integration with complementary metal oxide semiconductor(CMOS)fabrication processes have attracted great interest for their facilitation of polarized photodetector devices *** the polarized detection performance of low-dimensional materials to satisfy realistic needs stimulates the exploration of modulation of anisotropic *** this review,we comprehensively introduce the latest research progress in modulating the optical and optoelectronic anisotropy characteristics of low-dimensional *** strategy of anisotropy regulation through crystal structure engineering and coupling system is discussed ***,the latest progress in image recognition applications using anisotropic low-dimensional materials is reviewed in ***,we summarize the challenge and propose future opportunities in the practical application of polarized-sensitive imaging photodetectors based on low-dimensional anisotropic materials.

关键词： Anisotropy Polarized detection Image recognition Low-dimensional materials

Adversarial attacks against dynamic graph neural networks via node injection

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High-Confidence Computing 2024年第1期4卷 43-51页

作者： Yanan Jiang hui Xia School of Computer Science and Technology Ocean University of ChinaQingdao 266100China

Dynamic graph neural networks(DGNNs)have demonstrated their extraordinary value in many practical ***,the vulnerability of DNNs is a serious hidden danger as a small disturbance added to the model can markedly reduce its *** the same time,current adversarial attack schemes are implemented on static graphs,and the variability of attack models prevents these schemes from transferring to dynamic *** this paper,we use the diffused attack of node injection to attack the DGNNs,and first propose the node injection attack based on structural fragility against DGNNs,named Structural Fragility-based Dynamic Graph Node Injection Attack(SFIA).SFIA firstly determines the target time based on the period ***,it introduces a structural fragile edge selection strategy to establish the target nodes set and link them with the malicious node using serial ***,an optimization function is designed to generate adversarial features for malicious *** on datasets from four different fields show that SFIA is significantly superior to many comparative *** the graph is injected with 1%of the original total number of nodes through SFIA,the link prediction Recall and MRR of the target DGNN link decrease by 17.4%and 14.3%respectively,and the accuracy of node classification decreases by 8.7%.

关键词： Dynamic graph neural network Adversarial attack Malicious node Vulnerability

Vision-Based Adaptive Prescribed-Time Control of UAV for Uncooperative Target Tracking with Performance Constraint

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Journal of Systems Science & Complexity 2024年第5期37卷 1956-1977页

作者： SHE Xuehua MA hui REN Hongru LI Hongyi School of Automation and the Guangdong Provincial Key Laboratory of Intelligent Decision and Cooperative Control Guangdong University of TechnologyGuangzhou 510006China School of Mathematics and Statistics Guangdong University of TechnologyGuangzhou 510006China College of Electronic and Information Engineering and Chongqing Key Laboratory of Generic Technology and System of Service Robots Southwest UniversityChongqing 400715China

This paper discusses the uncooperative target tracking control problem for the unmanned aerial vehicle(UAV)under the performance constraint and scaled relative velocity constraint,in which the states of the uncooperative target can only be estimated through a vision *** the limited detection range,a prescribed performance function is designed to ensure the transient and steady-state performances of the tracking ***,the scaled relative velocity constraint in the dynamic phase is taken into account,and a time-varying nonlinear transformation is used to solve the constraint problem,which not only overcomes the feasibility condition but also fails to violate the constraint ***,the practically prescribed-time stability technique is incorporated into the controller design procedure to guarantee that all signals within the closed-loop system are *** is proved that the UAV can follow the uncooperative target at the desired relative position within a prescribed time,thereby improving the applicability of the vision-based tracking *** results have been presented to prove the validity of the proposed control strategy.

关键词： Nonlinear transformation performance constraint prescribed-time tracking uncooperative target vision-based measurement

Effects of physical properties of supercritical water on heat transfer characteristics of single particle within a particle cluster Author links open overlay panel

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Particuology 2024年第8期91卷 291-302页

作者： Xiaoyu Li Bowei Zhang huibo Wang hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an710049China

The complex physical properties of supercritical water(SCW)make the heat transfer characteristics of particles within a particle cluster *** heat transfer characteristics of single particle within a particle cluster in SCW,influenced by surrounding particles,have not been effectively *** numerical simulations were conducted to investigate the heat transfer characteristics of particle clusters in SCW under different *** results were compared and analyzed with those from constant property *** was found that Reynolds number(Re)and the void fraction of particle cluster have no special effects on the variation trends of Nusselt number(Nu)for the focused ***,the particle temperature had a significant effect on the variation trends of *** effect of Re on the heat transfer rate exponent(η)of the focused particle can be divided into two zones:a significant effect zone and a non-significant effect *** effect of void fraction onηin the non-significant effect zone was *** the non-significant effect zone,ηdecreased with the increasing particle *** the significant effect zone,the variation trends ofηbecame more *** fundamental reason for this series of phenomena is the changes in distribution of physical properties.A model forηwas developed for the non-significant effect *** model can filter out the effects of Re and certain particle cluster spatial configurations,and it demonstrates good predictive performance.

关键词： Supercritical water Particle cluster Heat transfer characteristics Heat transfer rate exponent Physical properties correction

Microstructure evolution and mechanical properties of brazing joint for ultra-thin-walled Inconel 718 considering grain size effect and brazing temperature

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Chinese Journal of Aeronautics 2024年第2期37卷 541-556页

作者： Rui ZHAO Yueshuai SONG hui KANG Min WAN School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Jiangxi Research Institute of Beihang University Jiangxi 330000China

The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high demands on its *** achieve this objective,this study investigates the impact of three distinct brazing temperatures and five typical grain sizes on the brazed joints’mechanical properties and microstructure evolution *** evolution analysis was conducted based on Electron Back Scatter Diffraction(EBSD),Scanning Electron Microscopy(SEM),X-Ray Diffraction(XRD),High-Resolution Transmission Electron Microscopy(HRTEM),and Focused Ion Beam(FIB).Besides,the mechanical properties and fracture behavior were studied based on the uniaxial tension tests and in-situ tension *** findings reveal that the brazing joint’s strength is higher for the fine-grain capillary than the coarse-grain one,primarily due to the formation of a dense branch structure composed of G-phase in the brazing *** effects of grain size,such as pinning and splitting,are amplified at higher brazing ***,micro-cracks initiate around brittle intermetallic compounds and propagate through the eutectic zone,leading to a cleavage fracture *** fracture stress of fine-grain specimens is higher than that of coarse-grain due to the complex micro-crack ***,this study contributes significantly to the literature by highlighting the crucial impact of grain size on the brazing properties of ultra-thin-walled Inconel 718 structures.

关键词： EYWORDS Ultra-thin-walled structure Brazing Inconel 718 Grain size effect Brazing temperature

Recent progresses in thermal treatment of β-Ga_(2)O_(3) single crystals and devices

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1659-1677页

作者： Yuchao Yan Zhu Jin hui Zhang Deren Yang State Key Laboratory of Silicon and Advanced Semiconductor Materials and School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices ZJU-Hangzhou Global Scientific and Technological Innovation CenterHangzhou 311200China

In recent years,ultra-wide bandgap β-Ga_(2)O_(3) has emerged as a fascinating semiconductor material due to its great potential in power and photoelectric *** semiconductor industrial,thermal treatment has been widely utilized as a convenient and effective approach for substrate property modulation and device ***,a thorough summary of β-Ga_(2)O_(3) substrates and devices behaviors after high-temperature treatment should be *** this review,we present the recent advances in modulating properties of β-Ga_(2)O_(3) substrates by thermal treatment,which include three major applications:(ⅰ)tuning surface electrical properties,(ⅱ)modifying surface morphology,and(ⅲ)oxidating ***,regulating electrical contacts and handling with radiation damage and ion implantation have also been discussed in device *** each category,universal annealing conditions were speculated to figure out the corresponding problems,and some unsolved questions were proposed *** review could construct a systematic thermal treatment strategy for various purposes and applications of β-Ga_(2)O_(3).

关键词： β-gallium oxide thermal treatment substrates devices