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Reconstruct defect features in ultrasonic scan data by multi-time local outlier factors

Measurement 2025年

作者： Peng Yin Fei Wang Yunyan Liu Peng Song Jianghao Zhao Zhuoyan Yue Yaodong Yang Honghao Yue Junyan Liu State Key Laboratory of Robotics and System (HIT) Harbin 150001 PR China School of Mechatronics Engineering Harbin Institute of Technology Harbin 150001 PR China Beijing Satellite Manufacturing Factory Co. LTD Beijing 100001 PR China

In this paper, a novel multi-time Local Outlier Factor (MT-LOF) algorithm is proposed to address the challenges posed by the low efficiency of automated imaging of ultrasound data and the difficulty of reusing the results. MT-LOF is employed to summarize ultrasound outlier signals at multiple time points and reconstruct detection results. Additionally, phased array ultrasonic testing (PAUT) boards are utilized to collect data from flat-bottomed holes, simulated impact components, and real specimens. The collected data is then processed using the MT-LOF and gate peak method, and the results are compared. The findings of the research suggest that MT-LOF can effectively streamline the ultrasonic signal processing process, achieve automated characterization of ultrasonic defect data, and concurrently enhance the signal-to-noise ratio (SNR) of the impact simulation sample experiment by 176.7% in comparison with conventional methods, while concomitantly reducing the background standard deviation by 44.7%.

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Theoretical and experimental research on static stiffness,performance,and lift-off characteristics of multi-layer gas foil thrust bearings

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Friction 2024年第11期12卷 2458-2479页

作者： Yang HU Pengjing DING Fangling WU Xiaojing WANG Bo LIANG Yonggang MENG School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200072China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing Engineering Institute of Aircraft SystemsNanjing 211106China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

In this study,a new comprehensive fully coupled elastic–hydrodynamic model is developed for a multi-layer gas foil thrust bearing(GFTB).The interaction effects among the top foil,back board,middle foil,and bottom foil,as well as the Coulomb friction effect,are *** stiffness and static characteristics obtained by the experimental and theoretical approaches are in good agreement,which verifies the accuracy of the *** contribution of each foil layer to the overall stiffness and the load-carrying mechanism are *** effects of the load,preload,and rotational speed on the static performance are investigated ***,start–stop tests are performed to achieve the lift-off speed,start-up torque,and shut-down torque under various operating conditions.

关键词： multi-layer gas foil thrust bearing(GFTB) load carrying mechanism static performance

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Hierarchical Optimization of Landing Performance for Lander with Adaptive Landing Gear

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Chinese Journal of Mechanical engineering 2019年第2期32卷 24-35页

作者： Zongmao Ding Hongyu Wu Chunjie Wang Jianzhong Ding School of Mechanical Engineering and Automation Beijing University of Aeronautics and Astronautics Beijing System Design Institute of Electro-Mechanic Engineering China Aerospace Science and Industry Corporation Limited Department of Mechanical Engineering Tsinghua University State Key Laboratory of Virtual Reality and Systems Beijing University of Aeronautics and Astronautics

A parameterized dynamics analysis model of legged lander with adaptive landing gear was established. Based on the analysis model, the landing performances under various landing conditions were analyzed by the optimized Latin hypercube experimental design method. In order to improve the landing performances, a hierarchical optimization method was proposed considering the uncertainty of landing conditions. The optimization problem was divided into a higher level(hereafter the "leader") and several lower levels(hereafter the "follower"). The followers took condition?ing factors as design variables to find out the worst landing conditions, while the leader took bu er parameters as design variables to better the landing performance under worst conditions. First of all, sensitivity analysis of landing conditioning factors was carried out according to the results of experimental design. After the sensitive factors were screened out, the response surface models were established to reflect the complicated relationships between sensi?tive conditioning factors, bu er parameters and landing performance indexes. Finally, the response surface model was used for hierarchical optimization iteration to improve the computational e ciency. After selecting the optimum bu er parameters from the solution set, the dynamic model with the optimum parameters was simulated again under the same landing conditions as the simulation before. After optimization, nozzle performance against damage is improved by 5.24%, the acceleration overload is reduced by 5.74%, and the primary strut improves its performance by 21.10%.

关键词： Landing gear Soft landing Sensitivity analysis Response surfaces Hierarchical optimization

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Study on echo fidelity of radar simulator

Study on echo fidelity of radar simulator

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2014 International Conference on Manufacturing Technology and Electronics Applications, ICMTEA 2014

作者： Xu, Yin Hui Wang, Fu Zhi Liu, Yi Long Zeng, Da Zhi Beijing Institute of Technology Beijing China The State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System Luoyang China

ISBN: (纸本)9783038353287

Echo fidelity is an important characteristic of radar simulator and it influences accuracy and reliability of radar test directly. This paper introduces the research status of simulator fidelity and sort out the definition and property of radar echo simulation fidelity. Then we propose the numerical calculation methods for individual indicators, including similarity calculation, dissimilarity computing and interval changes three parts. Finally, on the basis of the evaluation system, we propose two calculation methods for entirety fidelity, they are weighted numerical calculation and umbrella figure methods. © (2014) Trans Tech Publications, Switzerland.

关键词： Radar simulators

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Localized space-tim e method of fundamental solutions for three-dimensional transient diffusion problem

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Acta Mechanica Sinica 2020年第5期36卷 1051-1057,I0002页

作者： L.Qiu J.Lin Q.-H.Qin W.Chen International Center for Simulation Software in Engineering and Sciences College of Mechanics and MaterialsHohai UniversityNanjing 210098China College of Engineering and Computer Science Australian National UniversityCanberraACT 2601Australia State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Acoustic Institute of AcousticsChinese Academy of SciencesBeijing 100190China

A localized space-time method of fundamental solutions(LSTMFS)is extended for solving three-dimensional transient diffusion problems in this *** interval segmentation in temporal direction is developed for the accurate simulation of long-time-dependent diffusion *** the LSTMFS,the whole space-time domain with nodes arranged i divided into a series of overlapping subdomains with a simple *** each subdomain,the conventional method of fundamental solutions is utilized and the coefficients associated with the considered domain can be explicitly *** calculating a combined sparse matrix system,the value at any node inside the space-time domain can be *** experi-ments demonstrate that high accuracy and efficiency can be simultaneously achieved via the LSTMFS,even for the problems defined on a long-time and quite complex computational domain.

关键词： Localized spacetime method of fundamental solutions Meshless method Long-time evolution Transient diffusion

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智能隐蔽通信——最新进展与未来研究趋势（英文）

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engineering 2025年第1期 101-111页

作者：李赞石嘉司江勃吕璐关磊郝本建铁壮壮王丹洋邢成文 Tony Q.S.Quek State Key Laboratory of Integrated Service Networks School of Telecommunications Engineering Xidian University School of Information and Electronics Beijing Institute of Technology Information System Technology and Design Pillar Singapore University of Technology and Design

With the future substantial increase in coverage and network heterogeneity, emerging networks will encounter unprecedented security threats. Covert communication is considered a potential enhanced security and privacy solution for safeguarding future wireless networks, as it can enable monitors to detect the transmitter's transmission behavior with a low probability, thereby ensuring the secure transmission of private information. Due to its favorable security, it is foreseeable that covert communication will be widely used in various wireless communication settings such as medical, financial, and military scenarios. However, existing covert communication methods still present many challenges toward practical applications. In particular, it is difficult to guarantee the effectiveness of covert schemes based on the randomness of eavesdropping environments, and it is challenging for legitimate users to detect weak covert signals. Considering that emerging artificial-intelligence-aided transmission technologies can open up entirely new opportunities to address the above challenges, we provide a comprehensive review of recent advances and potential research directions in the field of intelligent covert communications in this work. First, the basic concepts and performance metrics of covert communications are introduced. Then, existing effective covert communication techniques in the time, frequency, spatial, power, and modulation domains are reviewed. Finally, this paper discusses potential implementations and challenges for intelligent covert communications in future networks.

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Two types of coaxial self-balancing robots

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Journal of Central South University 2013年第11期20卷 2981-2990页

作者：高学山戴福全李潮全 School of Mechatronical Engineering Beijing Institute of Technology State Key Laboratory of Robotics and System (Harbin Institute of Technology) School of Mechanical and Automotive Engineering Fujian University of Technology Navigation and Control Institute of China North Industries Group Corporation

Two types of coaxial self-balancing robots(CSBR)were proposed,one can be used as a mobile robot platform for parts transporting in unmanned factory or as an inspector in dangerous areas,and the other can be used as a personal transporter ridden in *** designing and control structures as well as control strategies were described and compared in order to get a general way to develop such robots.A state feedback controller and a fuzzy controller were designed for the robot using DC servo motors and the robot using torque motors,*** experiments indicate that the robots can realize various desired operations smoothly and agilely at the velocity of 0.6 m/s with an operator of 65 ***,the robustness of the controllers is revealed since these controllers can stabilize the robot even with unknown external disturbances.

关键词： mobile robots service robots mechatronic systems robot dynamics control of robotic systems

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Capacity Allocation of Hybrid Power system with Hot Dry Rock Geothermal Energy,Thermal Storage,and PV Based on Game Approaches

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Journal of Modern Power systems and Clean Energy 2023年第1期11卷 290-301页

作者： Yang Si Laijun Chen Xuelin Zhang Xiaotao Chen Shengwei Mei Qinghai Key Lab of Efficient Utilization of Clean Energy(Tus-Institute for Renewable Energy) University of QinghaiXining 810016China State Key Laboratory of Control and Simulation of Power System and Power Generation Equipment(Electric Machinery Department Tsinghua University)Beijing 100084China Technical Institute of Physics and Chemistry Beijing 100190China IEEE

This study utilizes hot dry rock(HDR)geothermal energy,which is not affected by climate,to address the capacity allocation of photovoltaic(PV)-storage hybrid power systems(HPSs)in frigid plateau *** study replaces the conventional electrochemical energy storage system with a stable HDR plant assisted by a flexible thermal storage(TS)*** HPS consisting of an HDR plant,a TS plant,and a PV plant is *** approaches are introduced to establish the game pattern model of the proposed HPS as the *** annualized income of each player is used as the payoff ***,non-cooperative game and cooperative game approaches for capacity allocation are proposed according to the interests of each player in the proposed ***,the proposed model and approaches are validated by performing calculations for an HPS in the Gonghe Basin,Qinghai,China as a case *** results show that in the proposed non-cooperative game approach,the players focus only on the individual payoff and neglect the overall system *** proposed cooperative game approach for capacity allocation improves the flexibility of the HPS as well as the payoff of each game ***,the HPS can better satisfy the power fluctuation rate requirements of the grid and increase the equivalent firm capacity(EFC)of PV plants,which in turn indirectly guarantees the reliability of grid operation.

关键词： Capacity allocation equivalent firm capacity game theory hot dry rock hybrid power system

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Adaptive terminal sliding mode control for flexible air-breathing hypersonic vehicle

Adaptive terminal sliding mode control for flexible air-brea...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2021

作者： Qin, Decong Chen, Haibing Lin, Wei Tang, Peng Ma, Tielin Xu, Cheng School of Transportation Science and Engineering Beihang University Beijing China Aircraft/Engine Integrated System Safety Beijing Key Laboratory Beijing China Beijing System Design Institute of the Electro-mechanic Engineering Beijing China Institute of Unmanned System Beihang University Beijing China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China

ISBN: (纸本)9781624106095

Flexible air-breathing hypersonic vehicles show significant and complex aerodynamic, scramjet propulsion system, flight dynamic and elastic coupling characteristics, which usually are highly nonlinear. These result in huge uncertainties, parameter perturbation and internal disturbance, which can no longer be ignored, and therefore, extreme difficulties for flight control design. A unique parameter adaptive non-singular terminal sliding mode method is proposed for longitudinal control law design of a flexible coupling air-breathing hypersonic vehicle. This method uses adaptive reaching law gain instead of additional adaptive compensation term to handle the uncertainty to improve robustness. The stability of the close loop system is proved via a Lyapunov way. The longitudinal tracking control law for velocity and angle of attack is designed based on a rigid dynamic model of a flexible air-breathing hypersonic vehicle. A strong coupling model of the same vehicle, considering aerodynamic-scramjet engine-flight dynamic-elastic couplings, is established as the verification platform of control law designed. simulation results obtained based on the coupling model demonstrate that the control law designed has good performance and acceptable robustness. © 2021, American institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Hypersonic vehicles

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A computer control and monitoring system for high power converters

A computer control and monitoring system for high power conv...

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ICEMS 2005: 8th International Conference on Electrical Machines nd systems

作者： Rong, Yi Zhenming, Zhao Xiaoying, Sun Liqiang, Yuan Jue, Qian Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100086 China

ISBN: (纸本)7506274078

Computer control and monitoring system (CCMS) is quite important for high power converters (HPCs) operation. This paper presents a novel CCMS, which integrates a database management system (DBMS) into the monitoring software to get the beneficial features such as simple configuration and compact structure. In its communication system, an advanced optical fiber communication (OFC) technology is applied and priority-based communications is proposed to improve the reliability and the real time of the communications. Furthermore, a friendly standard Windows human-machine interface (HMI) is provided. The reliability and performance of the system are verified by system tests and practical operations.

关键词： Power converters

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