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19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Liu, Tao Yuan, Weihan Hou, Weijie Zang, Libin Li, Yuehua Zhao, Baoshan Sun, Hao School of Electrical Engineering TianGong University Tianjin China Tianjin Institute of Aerospace Mechanical and Electrical Equipment Tianjin China Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin China

ISBN: (纸本)9789819613861

As space technology advances, the exploration of small celestial bodies has become a major research focus, necessitating more stringent requirements for microgravity simulation technology. The microgravity simulation device featuring a magnetically induced zero-stiffness structure is utilized in ground simulation experiments for small celestial body detectors. This device integrates a magnetoelectric coupling system, motor control system, and stiffness coupling system to achieve a quasi-zero stiffness state under high load conditions. However, its complex structure and high nonlinearity complicate the tuning of control parameters. To tackle this issue, this paper presents a tuning method that merges model identification and parameter optimization for the magnetically induced zero-stiffness microgravity simulation device. The proposed approach employs a combination of pseudo-random signals and the instrumental variable method for model identification of the microgravity system. Subsequently, genetic algorithms are used to optimize the control parameters, thereby shortening the tuning process. simulation and experimental results indicate that the control accuracy of the microgravity simulation system surpasses 98%, demonstrating the method’s feasibility and effectiveness. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： microgravity

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Deciphering environmental factors influencing phytoplankton community structure in a polluted urban river

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Journal of environmental Sciences 2025年第2期148卷 375-386页

作者： Xiaxia Li Kai Chen Chao Wang Tianyu Zhuo Hongtao Li Yong Wu Xiaohui Lei Ming Li Bin Chen Beibei Chai School of Water Conservancy and Hydroelectric Power Hebei University of EngineeringHandan 056038China Collaborative Innovation Center for Intelligent Regulation and Comprehensive Management of Water Resources School of Water Conservancy and HydroelectricHebei University of EngineeringHandan 056038China Hebei Key Laboratory of Intelligent Water Conservancy Hebei University of EngineeringHandan 056038China Tianjin Water Group Binhai Water Co. Ltd.Tianjin 300308China State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China School of Architecture and Civil Engineering Xi’an University of Science and TechnologyXi’an 710054China Chengdu University of Technology Chengdu 610059China College of Natural Resources and Environment Northwest A&F UniversityYangling 712100China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentBeijing Normal UniversityBeijing 100875China

Tuojiang River Basin is a first-class tributary of the upper reaches of the Yangtze River—which is the longest river in *** phytoplankton are sensitive indicators of trophic changes inwater bodies,characterizing phytoplankton communities and their growth influencing factors in polluted urban rivers can provide new ideas for pollution ***,we used direct microscopic count and environmental DNA(eDNA)metabarcoding methods to investigate phytoplankton community structure in Tuojiang River Basin(Chengdu,Sichuan Province,China).The association between phytoplankton community structure and water environmental factors was evaluated by Mantel *** environmental monitoring data were used to pinpoint major factors that influenced phytoplankton growth based on structural equation *** the phylum level,the dominant phytoplankton taxa identified by the conventional microscopic method mainly belonged to Bacillariophyta,Chlorophyta,and Cyanophyta,in contrast with Chlorophyta,Dinophyceae,and Bacillariophyta identified by eDNA ***α-diversity analysis,eDNA metabarcoding detected greater species diversity and achieved higher precision than the microscopic *** growth was largely limited by phosphorus based on the nitrogen-to-phosphorus ratios>16:1 in all water *** analysis and structural equation modeling also confirmed that the nitrogen-to-phosphorus ratio was the principal factor influencing phytoplankton *** results could be useful for implementing comprehensive management of the river basin *** is recommended to control the discharge of point-and surface-source pollutants and the concentration of dissolved oxygen in areas with excessive nutrients(e.g.,Jianyang-Ziyang).Algae monitoring techniques and removal strategies should be improved in 201 Hospital,Hongrihe Bridge and Colmar Town areas.

关键词： environmental DNA Microscopic count Phytoplankton growth Structural equation modeling Tuojiang River Basin

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A novel approach for developing Ti6Al4V-Cu alloy with exceptional properties using a developed metallic printer of LPBF

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Materials and Design 2025年 254卷

作者： Gu, Qinming Zhang, Zhenyu Zhou, Hongxiu Wang, Dong Gu, Yang Zhao, Baoshan Yan, Lijia Chen, Tao Chen, Leilei Cancer Hospital of Dalian University of Technology Liaoning Cancer Hospital & Institute State Key Laboratory of High-performance Precision Manufacturing Dalian University of Technology Dalian 116024 China Dianxi Research Institute of Dalian University of Technology Baoshan 678000 China School of Mechanical and Electrical Engineering Hainan University Haikou 570228 China School of Energy and Power Engineering Dalian University of Technology Dalian 116024 China Tianjin Key Laboratory of Aerospace Intelligent Equipment Technology Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin Institute of Aerospace Mechanical and Electrical Equipment Tianjin 300301 China Department of Security Hainan University Haikou 570228 China School of Future Science and Engineering Soochow University Suzhou 215200 China China Yangtze Power Co. Ltd. Yichang 443002 China

Ti6Al4V has no antimicrobial performance, and copper (Cu) is usually added in Ti6Al4V implants. Nevertheless, brittle Ti2Cu will be precipitated, greatly affecting the elongation of Ti6Al4V-Cu. To solve these challeng... 详细信息

Ti6Al4V has no antimicrobial performance, and copper (Cu) is usually added in Ti6Al4V implants. Nevertheless, brittle Ti₂Cu will be precipitated, greatly affecting the elongation of Ti6Al4V-Cu. To solve these challenges, a novel approach is proposed to prepare Ti6Al4V-Cu alloy using a developed metallic printer of laser powder bed fusion (LPBF). At an optimized laser energy density of 39.51 J/mm³ and 1 wt% Cu, the relative density of Ti6Al4V-Cu is 99.7 %. The ultimate tensile strength and compressive strength of prepared Ti6Al4V-Cu are 1382.35 and 1882.13 MPa, respectively, representing increases of 14.4 % and 36.9 % compared to those of Ti6Al4V. Meantime, the friction coefficient and wear rate are 0.39 and 3.99 × 10⁻⁴ mm³/N∙m, decreasing 46.38 % and 38.29 % correspondingly. Furthermore, electrochemical experiments show that the resistance value of passivated film on Ti6Al4V-Cu is 2.19 × 10⁶ Ω·cm², which is 1.38 times that of Ti6Al4V. Cu atoms were dissolved in Ti6Al4V matrix, leading to the decomposition of the Ti₂Cu phase. The improvement of mechanical, tribological and corrosion resistance properties is attributed to grain refinement, solution strengthening, grain boundary strengthening and decomposition of Ti₂Cu. Our findings provide new insights to prepare Ti6Al4V-Cu with outstanding properties using LPBF, which has bright prospect in aerospace and medical restorations. © 2025 The Author(s)

关键词： Corrosion resistance Laser powder bed fusion Mechanical performance Ti6Al4V-Cu Tribological property

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Convex optimization of asteroid landing trajectories driven by solar radiation pressure

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Chinese Journal of Aeronautics 2022年第12期35卷 200-211页

作者： Chuanjun DONG Hongwei YANG Shuang LI Bo LI College of Astronautics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin 300458China Tianjin Institute of Aerospace Mechanical and Electrical Equipment Tianjin 300458China

High-area/mass ratio landers driven by Solar Radiation Pressure(SRP)have potential applications for future asteroid landing *** paper develops a new convex optimization-based method for planning trajectories driven by SRP.A Minimum Landing Error(MLE)control problem is formulated to enable planning SRP-controlled trajectories with different flight *** is transformed into Second Order Cone Programming(SOCP)successfully by a series of different convexification technologies.A trust region constraint and a modified MLE objective function are used to guarantee the convergence performance of the optimization ***,the SRP-driven trajectory optimal control problem is converted equivalently into a sequence of convex optimal control problems that can be solved effectively.A set of numerical simulation results has verified the effectiveness and feasibility of the proposed optimization method.

关键词： Asteroids Convex optimization Optimal control Soft landing Solar radiation pressure Trajectory optimization

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Gravity compensation method via magnetic quasi-zero stiffness combined with a quasi-zero deformation control strategy

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Science China(Technological Sciences) 2022年第8期65卷 1738-1748页

作者： ZHOU Rui ZHOU YiFan CHEN XueDong HOU WeiJie WANG Chang WANG Hao JIANG Wei State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin Institute of Aerospace Mechanical and Electrical EquipmentTianjin 300301China Institute of Artificial Intelligence Huazhong University of Science and TechnologyWuhan 430074China

Gravity compensation refers to the creation of a constant supporting force to fully or partly counteract the gravitational force for ground verification to simulate the spacecraft dynamics in outer space with zero-or micro-gravity. Gravity compensation is usually implemented via a very low stiffness suspension/supporting unit, and a servo system in series is adopted to extend the simulation range to hundreds of millimeters. The error of suspension force can be up to tens of Newton due to the contact/friction in the suspension/supporting unit and the error of the force/pressure sensor. It has become a bottleneck for the ground verification of spacecraft guidance, navigation, and control systems with extreme requirements, such as tons of payload and fine thrust in sub-Newtons. In this article, a novel gravity compensation method characterized by quasi-zero stiffness plus quasi-zero deformation(QZS-QZD) is proposed. A magnetic negative stiffness spring in parallel with positive springs and aerostatic bearing is adopted to form a QZS supporting unit, and disturbance forces, such as contact or friction, can be eliminated. The deformation of the QZS supporting unit is measured via a displacement sensor, and the QZD control strategy is applied to guarantee the force error of gravity compensation to be less than sub-newtons and irrelevant to the payload. The principle of gravity compensation with QZS-QZD is analyzed, and performance tests on a prototype are carried out. The results show that when the spacecraft moves smoothly, the absolute force error is less than 0.5 N, the relative error of gravity compensation is less than 0.1%, and when collisions with other objects occur, the relative errors are 0.32% and 0.65%. The proposed method can significantly improve the gravity compensation accuracy in comparison with conventional approaches.

关键词： gravity compensation zero-gravity ground verification quasi-zero stiffness quasi-zero deformation

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A bio-inspired spider-like structure isolator for low-frequency vibration

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Applied Mathematics and Mechanics(English Edition) 2023年第8期44卷 1263-1286页

作者： Guangdong SUI Shuai HOU Xiaofan ZHANG Xiaobiao SHAN Chengwei HOU Henan SONG Weijie HOU Jianming LI State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China School of Astronautics Harbin Institute of TechnologyHarbin 150001China Yangtze River Delta HIT Robot Technology Research Institute Wuhu 241000Anhui ProvinceChina Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin 300301China

This paper proposes a quasi-zero stiffness(QZS)isolator composed of a curved beam(as spider foot)and a linear spring(as spider muscle)inspired by the precise capturing ability of spiders in vibrating *** curved beam is simplified as an inclined horizontal spring,and a static analysis is carried out to explore the effects of different structural parameters on the stiffness performance of the QZS *** finite element simulation analysis verifies that the QZS isolator can significantly reduce the first-order natural frequency under the load in the QZS *** harmonic balance method(HBM)is used to explore the effects of the excitation amplitude,damping ratio,and stiffness coefficient on the system’s amplitude-frequency response and transmissibility performance,and the accuracy of the analytical results is verified by the fourth-order Runge-Kutta integral method(RK-4).The experimental data of the QZS isolator prototype are fitted to a ninth-degree polynomial,and the RK-4 can theoretically predict the experimental *** experimental results show that the QZS isolator has a lower initial isolation frequency and a wider isolation frequency bandwidth than the equivalent linear *** frequency sweep test of prototypes with different harmonic excitation amplitudes shows that the initial isolation frequency of the QZS isolator is 3 Hz,and it can isolate 90%of the excitation signal at 7 *** proposed biomimetic spider-like QZS isolator has high application prospects and can provide a reference for optimizing low-frequency or ultra-low-frequency isolators.

关键词： bionic isolation structure curved beam nonlinear stiffness quasi-zero stiffness(QzS) low-frequency vibration isolator

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Harmonic Current Suppression Scheme for Dual Three-Phase PMSM Based on Harmonic Subspace Phase-Shifting Operation 27

Harmonic Current Suppression Scheme for Dual Three-Phase PMS...

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27th International Conference on Electrical Machines and Systems, ICEMS 2024

作者： Ma, Xiaochen Li, Bin Rui, Xuefeng Hou, Weijie School of Electrical and Information Engineering Tianjin University Tianjin300072 China Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin300301 China

ISBN: (纸本)9784886864406

This paper proposes a new harmonic current suppression scheme for dual three-phase permanent-magnet synchronous motor. First, based on the harmonic subspace in the classical vector space decomposition model, the two actual currents under rotating coordinate system are respectively shifted by 90 degrees to construct two virtual currents. Then, by further performing the 6th Park transformation on these actual and virtual currents, the main harmonic current components (5th and 7th) in the motor are naturally converted into four sets of DC values. As a result, there is no need to use any additional filters for harmonic extraction, and harmonic suppression can be achieved through simple proportional-integral control. Consequently, the drawbacks of conventional harmonic suppression schemes based on low-pass filters or resonant controllers can be avoided. Experimental results are provided to verify the effectiveness of the proposed scheme. © 2024 The Institute of Electrical Engineers of Japan.

关键词： Low pass filters

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Finite-time stability analysis of linear time-varying systems: A numerical algorithm 15

Finite-time stability analysis of linear time-varying system...

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15th IEEE International Conference on Mechatronics and Automation, ICMA 2018

作者： Chen, Zhihua Xie, Yongchun Beijing Institute of Control Engineering China Science and Technology on Space Intelligent Control Laboratory Beijing China Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin China

ISBN: (纸本)9781538660720

Under the perspective of numerical computation, this paper investigates the finite-time stability (FTS) of continuous linear time-varying (LTV) systems when all its initial values are confined within a given polyhedral set while all its states are confined within a given ellipsoidal set. First, by solving a certain function optimization problem, the paper proposes a necessary and sufficient condition to guarantee the FTS of continuous LTV systems. Then, by utilizing the Lipschitz continuity of a certain function, two sufficient conditions to verify the FTS and finite-time instability of continuous LTV systems are proposed under the perspective of numerical computation, respectively. Furthermore, a novel numerical algorithm for analyzing the FTS of continuous LTV systems is deigned by converting a certain function optimization problem into a corresponding quadratic programming. Finally, a numerical example is given to illustrate the effectiveness of the proposed algorithm. © 2018 IEEE.

关键词： Quadratic programming

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On the stability of nonlinear time-varying spacecraft control systems 68

On the stability of nonlinear time-varying spacecraft contro...

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68th International Astronautical Congress: Unlocking Imagination, Fostering Innovation and Strengthening Security, IAC 2017

作者： Xie, Yongchun Chen, Zhihua Science and Technology on Space Intelligent Control Laboratory Beijing Institute of Control Engineering Beijing100094 China Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin330452 China

ISBN: (纸本)9781510855373

Stability is crucial for spacecraft control system. For rigid-body satellites or rigid-body satellites with flexible appendages, the closed-loop control systems are linear time-invariant (LTI) systems when linear controller, such as PID controllers are used. The stability of such kind of systems is usually analyzed by the Nyquist criterion. And the gain margin and phase margin of the control systems can be obtained. But for spacecraft with the consumption of liquid propellants, the Nyquist method is no longer suitable for stability analysis, especially when nonlinear controllers are used. Though Lyapunov stability analysis method can be used for time-varying linear or nonlinear systems, it cannot provide the stability margin that is widely used in engineering, thus limiting its practical applications. In order to solve this problem, a new framework for stability analysis of nonlinear time-varying systems based on computer simulation, which is suitable for engineering applications, is discussed in this paper. And some preliminary theoretical results are introduced. © 2017 International Astronautical Federation IAF. All rights reserved.

关键词： Closed loop control systems

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Stochastic P-Bifurcation of bistable van der pol system under fractional Gaussian noise: Theory and experiment

Stochastic P-Bifurcation of bistable van der pol system unde...

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2020 Asia-Pacific Conference on Image Processing, Electronics and Computers, IPEC 2020

作者： Song, Kailing Wu, Zhiqiang Zhang, Yue Li, Yuehua Tianjin University Mechanical and Engineering School Tianjin China Tianjin Institute of Aerospace Mechanical and Electrical Equipment Tianjin China Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin China

ISBN: (纸本)9781728160665

In this paper, the stochastic P-bifurcation problem of bistable van der Pol systems under fractional Gaussian noise (fGn) is discussed. Using the random average method to predict the stochastic dynamic behavior of the system under fGn and to obtain the stable probability density function of the response amplitude of the system, and then using the singularity theory to obtain the critical condition of stochastic P-bifurcation of the system. The results show that the H index in the fGn can induce the stochastic P-bifurcation in system, and the larger the H index is, the larger the stable probability density distribution becoming the bimodal region is. It indicates that the noise intensity required for the stochastic P-bifurcation becomes larger, which is beneficial to improve the stability of the equilibrium point of the system. At the same time, the system under the numerical simulation and circuit experiment has the same results as the theoretical analysis, which further insures the correctness of the research results. © 2020 IEEE.

关键词： Probability density function

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