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MAVEN observation of magnetosonic waves in the Martian magnetotail region

Earth and Planetary Physics 2024年第2期8卷 317-325页

作者： ShangChun Teng JiCheng Sun JiaWei Gao Y.Harada Markus Fraenz DeSheng Han State Key Laboratory of Marine Geology School of Ocean and Earth ScienceTongji UniversityShanghai 200092China MNR Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136China Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Geophysics Kyoto UniversityKyotoJapan Max-Planck-Institute for Solar System Research GoettingenGermany

Magnetosonic waves are an important medium for energy transfer in collisionless space *** waves have been widely investigated in the upstream of the bow shock at *** waves are believed to originate from pickup ions or reflected *** utilizing MAVEN spacecraft data,we have observed the occurrence of quasi-perpendicularly propagating magnetosonic emissions near the proton gyrofrequency in the Martian magnetotail *** plasma waves are associated with a significant enhancement of proton and oxygen *** excited magnetosonic waves could possibly heat the protons through resonance and facilitate the ionospheric plasma *** results could be helpful to better understand the Mars’magnetospheric dynamics and offer insights into possible energy redistribution between waves and plasma in the Martian nightside magnetosphere.

关键词： Martian magnetotail region magnetosonic waves proton escape

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Dynamic Object Removal of Static 3D Point-Cloud Map Building in Casualty Collection Point

Dynamic Object Removal of Static 3D Point-Cloud Map Building...

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International Conference on Control, Automation, robotics and Vision (ICARCV)

作者： Haidong Wang Wanlei Li Yijie Dai Xiaogang Xiong Yunjiang Lou State Key Laboratory of Robotics and System School of Mechanical Engineering and Automation Harbin Institute of Technology ShenZhen Shenzhen China

ISBN: (数字)9798331518493

ISBN: (纸本)9798331518509

Understanding the environment is crucial for the autonomous navigation of vehicles. Accurately identifying and removing dynamic objects that cause occlusions and noisy pose issues is crucial to the task. The casualty collection point (CCP) is a designated location for treating casualties during disasters. These sites are commonly located in open fields to ensure that the injured receive timely and appropriate care. Therefore, the construction of a 3D map in CCP may encounter additional challenges. In this paper, we introduces a novel algorithm that integrates a learning-based multi-object detection network with a Kalman Filter tracking framework to remove dynamic object traces from the 3D map building, particularly in CCP scenarios, and it redirects attention on the velocity attribute of dynamic objects at the object-level scale. Additionally, we contribute a new dataset specifically designed for the CCP scenario. Comparative experiments conducted on the SemanticKITTI dataset and CCP dataset show that our proposed method achieves the state-of-the-art performance in removing traces of dynamic objects on 3D Map. Dataset is available at https://***/haidongwang96/ccp_dataset.

关键词： Point cloud compression Three-dimensional displays Simultaneous localization and mapping Heuristic algorithms Buildings Object detection Kalman filters Object recognition Noise measurement Vehicle dynamics

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Instability-Induced Origami Design by Topology Optimization

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Acta Mechanica Solida Sinica 2023年第4期36卷 506-513页

作者： Weiwei Wang Ke Liu Meiqi Wu Hongyuan Li Pengyu Lv Huiling Duan State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering ScienceBIC-ESATCollege of EngineeringPeking UniversityBeijing 100871China Department of Advanced Manufacturing and Robotics College of EngineeringPeking UniversityBeijing 100871China CAPT HEDPS and IFSACollaborative Innovation Center of MoEPeking UniversityBeijing 100871China

Instability-induced wrinkle patterns of thin sheets are ubiquitous in nature,which often result in origami-like patterns that provide inspiration for the engineering of origami *** by instability-induced origami patterns,we propose a computational origami design method based on the nonlinear analysis of loaded thin sheets and topology *** bar-and-hinge model is employed for the nonlinear structural analysis,added with a displacement perturbation strategy to initiate out-of-plane *** ideas from topology optimization,a continuous crease indicator is introduced as the design variable to indicate the state of a crease,which is penalized by power functions to establish the mapping relationships between the crease indicator and hinge *** the structural strain energy with a crease length constraint,we are able to evolve a thin sheet into an origami structure with an optimized crease *** examples with different initial setups are illustrated,demonstrating the effectiveness and feasibility of the method.

关键词： Origami structure Instability Topology optimization Bar-and-hinge model

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Rigid–flexible hybrid surfaces for water-repelling and abrasionresisting

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Friction 2023年第4期11卷 635-646页

作者： Songtao HU Weifeng HUANG Jinbang LI Tom REDDYHOFF Xiaobao CAO Xi SHI Zhike PENG Andrew DEMELLO Daniele DINI State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China School of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211China Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK Department of Chemistry and Applied Biosciences ETH ZurichZurich 8093Switzerland School of Mechanical Engineering Ningxia UniversityYinchuan 750021China

Droplets impacting solid superhydrophobic surfaces is appealing not only because of scientific interests but also for technological applications such as *** studies have designed artificial surfaces in a rigid–flexible hybrid mode to combine asymmetric redistribution and structural oscillation water-repelling principles,resolving strict impacting positioning;however,this is limited by weak mechanical *** we propose a rigid–flexible hybrid surface(RFS)design as a matrix of concave flexible trampolines barred by convex rigid *** a surface exhibits a 20.1%contact time reduction via the structural oscillation of flexible trampolines,and even to break through the theoretical inertial-capillary limit via the asymmetric redistribution induced by rigid ***,the surface is shown to retain the above water-repelling after 1,000 abrasion cycles against oilstones under a normal load as high as 0.2 N·mm−*** is the first demonstration of RFSs for synchronous waterproof and wearproof,approaching real-world applications of liquid-repelling.

关键词： surface droplet impact hydrophobic abrasion

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Designing Unpowered Shoulder Complex Exoskeleton via Contralateral Drive for Self-rehabilitation of Post-stroke Hemiparesis

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Journal of Bionic Engineering 2023年第3期20卷 992-1007页

作者： Ning Li Tie Yang Yang Yang Wenyuan Chen Peng Yu Chuang Zhang Ning Xi Ying Zhao Wenxue Wang State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang110016China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of SciencesShenyang110169China University of Chinese Academy of Sciences Beijing100049China Emerging Technologies Institute Department of Industrial and Manufacturing Systems EngineeringUniversity of Hong KongPokfulamHong Kong999077China Department of General Surgery Shengjing Hospital of China Medical UniversityShenyang110004China

Rehabilitation using exoskeleton robots can effectively remediate dysfunction and restore post-stroke survivors’ physical ability. However, low kinematic compatibility and poor self-participation of post-stroke patients in rehabilitation restrict the outcomes of exoskeleton-based therapy. The study presents an Unpowered Shoulder Complex Exoskeleton (USCE), consisting of Shoulder Girdle Mechanism (SGM), Ball-and-Socket Joint Mechanism (BSM), Gravity Compensating Mechanism (GCM) and Adjustable Alignment Design (AAD), to achieve self-rehabilitation of shoulder via energy transfer from the healthy upper limb to the affected counterpart of post-stroke hemiplegic patients. The SGM and AAD are designed to improve the kinematic compatibility by compensating for displacements of the glenohumeral joint with the adaptable size of USCE for different wearers. The BSM and GCM can transfer the body movement and energy from the healthy half of the body to the affected side without external energy input and enhance the self-participation with sick posture correction. The experimental results show that the USCE can provide high kinematic compatibility with 90.9% movement similarity between human and exoskeleton. Meanwhile, the motion ability of a post-stroke patient’s affected limb can be increased through energy transfer. It is expected that USCE can improve outcomes of home-based self-rehabilitation.

关键词： Unpowered exoskeleton Health-paralysis combination Energy transfer Self-rehabilitation Shoulder mechanism design

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Sound Insulation Properties of Truss-based Inertial Amplification Double-panel Acoustic Metamaterial

Sound Insulation Properties of Truss-based Inertial Amplific...

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2024 Photonics and Electromagnetics Research Symposium, PIERS 2024

作者： Sun, Y. Dong, J. Lee, H.P. Zheng, H. Shanghai Jiao Tong University State Key Laboratory of Mechanical System and Vibration Shanghai200240 China National University of Singapore Department of Mechanical Engineering Singapore117575 Singapore

ISBN: (纸本)9798350375909

In recent years, a wide variety of periodic structures have come to the fore in the requirements for innovative noise and vibration solutions which are lightweight and compact. The vibro-acoustic properties of these structures are mostly analyzed by means of sound transmission loss (STL) calculations. To improve the STL of such lightweight structures, especially sandwich structures, without greatly increasing the structural complexity and the total mass, a truss-based inertial amplification double-panel acoustic metamaterial is presented. A truss structure consists of two lumped masses and four rigidly massless bars connected by moment-free hinges. The truss-based double-panel metamaterial and the cavity inside it form a panel-cavity-panel vibro-acoustic system. For the sake of the efficient STL calculations, a semi-analytical method based on the energy generalized variational principle is promoted, which can obtain the vibro-acoustic characteristics of the acoustic metamaterial-acoustic cavity coupling system as well. The displacement of the panels and the sound pressure of cavity are expressed as Chebyshev orthogonal polynomials. The feasibility of the developed method for efficient STL prediction is verified by comparing with the conventional finite element method. On this basis, numerical results clearly show that compared with the original panel-cavity-panel system, the inertial amplification acoustic meta-material exhibits a remarkable sound insulation performance within a low-frequency range which induced by the additional truss structures. Finally, parametric studies of inertial amplification angle and the depth of the cavity are conducted to reveal the variations of sound insulation performance. These parametric studies provide a guideline for tuning the STL peaks of the double-panel acoustic metamaterial. © 2024 IEEE.

关键词： Trusses

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Influence of Parasitic Parameters on Dynamic Threshold Voltage Hysteresis of Silicon Carbide MOSFETs

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CSEE Journal of Power and Energy systems 2023年第6期9卷 2251-2262页

作者： Yumeng Cai Tong Sun Peng Sun Zhibin Zhao Xuebao Li Hui Wang Zhong Chen Boyuan Cao the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China the Department of Electrical Engineering University of ArkansasFayettevilleAR 72701USA the Electric Power Research Institute State Grid Shanghai Electric Power CompanyShanghai 200437China

Threshold voltage (V_(TH)) hysteresis affects the dynamic characteristics of silicon carbide (SiC) MOSFETs, whichin turn affects reliability of a device. In this paper, a dynamichysteresis curve is proposed as an evaluation method of theinfluence of V_(TH) hysteresis on the switching characteristics ofSiC MOSFETs. This method can eliminate the impact of triggerlevel and obtain the dynamic V_(TH). Furthermore, the influence ofparasitic parameters on dynamic V_(TH) hysteresis is theoreticallyanalyzed. Double pulse tests under different parasitic parametersare performed on three SiC MOSFETs with different gatestructures to verify the analysis. Results show that gate resistance(R_(G)) and source inductance (L_(S)) have more significant effectson dynamic V_(TH) hysteresis compared with gate inductance anddrain inductance. V_(TH) hysteresis phenomenon weakens withincrease of R_(G) or L_(S), which is related to device *** results presented in this paper can provide guidance forthe design of circuit parasitic parameters of SiC MOSFETs toregulate V_(TH) hysteresis.

关键词： Dynamic hysteresis curve parasitic parameters silicon carbide(SiC)MOSFETs switching characteristics threshold voltage hysteresis

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Smart Plant Application of Autonomous Decentralized systems with the Introduction of Edge Nodes 15

Smart Plant Application of Autonomous Decentralized Systems ...

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15th International Conference on Advanced Computer Theory and Engineering, ICACTE 2022

作者： Wang, Jingyang Zou, Tao Yang, Zhijia Wang, Hongrui Key Laboratory Of Networked Control System Institutes For Robotics And Intelligent Manufacturing Shenyang Institute Of Automation Chinese Academy Of Sciences Shenyang China Guangzhou University College Of Mechanical And Electrical Engineering Guangzhou China State Key Laboratory Of Robotics Key Laboratory Of Networked Control System Institutes For Robotics And Intelligent Manufacturing Shenyang Institute Of Automation Chinese Academy Of Sciences Shenyang China University Of Chinese Academy Of Sciences Beijing China

ISBN: (数字)9781665481809

ISBN: (纸本)9781665481809

This paper illustrates the application of an autonomous decentralized system introducing edge nodes in a smart factory. The nodes include atomic nodes, the most fundamental autonomic units constituting an autonomous decentralized system that are capable of independently extracting information from the data field and processing that information internally and simultaneously transmitting the processing results and other internal information to the data field proactively in a broadcast mode, where the transmitted information circulates in the data field. The group-based data field enables the sharing of information by atomic nodes. Grouped management nodes are the managers of the whole group, and edge nodes are the terminal intelligent control units of an intelligent autonomous decentralized system. Improvements in system decentralization, fault tolerance characteristics and flexibility of the system can lead to homogenization, autonomous control and autonomous coordination in complex manufacturing environments, as well as excellent online fault tolerance, online expansion and online maintenance of the system. In addition, it enhances the ever-changing and evolving control requirements by deconstructing the complexity in the system. © 2022 IEEE.

关键词： Fault tolerance

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Simulation of Arc Erosion on the Main Contact of On-Load Tap Changer 4th

Simulation of Arc Erosion on the Main Contact of On-Load Tap...

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4th International Symposium on Insulation and Discharge Computation for Power Equipment, IDCOMPU 2023

作者： Zhou, Yuanxiang Dai, Yasong Chen, Jianning Li, Yuhang Hou, Xuzhao Zhang, Zhen State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi830047 China

ISBN: (纸本)9789819974047

Long-term operation and switching of transformer on-load tap-changers can cause degradation and deterioration of the main contact material, even leading to contact arcing damage in severe cases. However, the arcing mechanism of the main contact during the switching has not been clarified yet. A magneto-hydrodynamic simulation method of main contact arcing has been proposed. The geometry of the main contact in transformer oil is simplified, and the simulation model of the arc temperature field of the main contact in transformer oil coupled with electric, magnetic, thermal and fluid fields is proposed. The dynamic evolution of the arc temperature has been investigated at peak currents of 2100 A, 1500 A, 600 A and 300 A, respectively. The results show that with the increase of the spacing between contacts, the temperature at arc core rises rapidly and then decreases slowly, and the temperature can reach 50177 K at 2100A. Due to the electron bombardment at the anode surface, the temperature at anode surface is higher than that at cathode surface under different chopped currents. The highest temperatures at anode and cathode surface can reach 4142.5 K and 4081.7 K respectively. © Beijing Paike Culture Commu. Co., Ltd 2024.

关键词： Deterioration

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Nonconvex Noise-Tolerant Neural Model for Repetitive Motion of Omnidirectional Mobile Manipulators

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IEEE/CAA Journal of Automatica Sinica 2023年第8期10卷 1766-1768页

作者： Zhongbo Sun Shijun Tang Jiliang Zhang Junzhi Yu the Department of Control Engineering Changchun University of TechnologyChangchun 130012China IEEE College of Information Science and Engineering Northeastern UniversityShenyang 110819China the State Key Laboratory for Turbulence and Complex Systems Department of Advanced Manufacturing and RoboticsCollege of EngineeringPeking UniversityBeijing 100871China

Dear Editor,Quadratic programming problems(QPs)receive a lot of attention in various fields of science computing and engineering applications,such as manipulator control[1].Recursive neural network(RNN)is considered t... 详细信息

关键词： directional programming hardware

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