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IET International Radar Conference 2015

作者： Wu, Runhui Liu, Jiaqi Liu, Xin Meng, Gang Ren, Aimin Qi, Zhaohui National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical Beijing100076 China

ISBN: (纸本)9781849199940

This paper presents a model of RCS characteristic of non-uniform plasma sheltering disk target, by considering the absorption and refraction of electromagnetic wave, and combining graphic electromagnetic and ray tracking methods. The results show that: (1) RCS is reduced more than 10dB at wide-band frequency of electromagnetic wave, when the incident direction of electromagnetic wave is near the vertical surface. (2)For optimization of RCS reduction scheme, it is effective to optimize the relation between the plasma parameters (including electronic density, collision frequency, over-dense target scale) and incident wavelength. When the area of over-dense surface was larger than the target scale, the larger the collision frequency could lead to greater RCS reduction. When the area of over-dense scale was smaller than target, the RCS reduction has to be achieved by increasing electronic density and collision frequency.

关键词： Radar cross section

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Motion design for a walking-promotion robot and an evaluation of the effects on walking motivation 16

Motion design for a walking-promotion robot and an evaluatio...

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16th International Conference on Ubiquitous Robots (UR)

作者： Matsushita, Yume Miki, Kenta Imazaike, Takuya Yamazoe, Hirotake Lee, Joo-Ho National Key Laboratory of Science & Technology on Test Physics & Numerical Mathematics Beijing China

ISBN: (纸本)9781728132327

Falls are one of the reasons why older people need to receive care. Walking training is effective for preventing older people from falling. Accordingly, various research related to walking training has been conducted. We aimed to introduce robots in walking training of older people, and we developed a walking-promotion robot. In this paper, we designed motions for promoting walking by older people and evaluated the effects on the participants motivation to walk and the impression of the robot conveyed by the robots motions. From the experimental results, we confirmed that a robot did affect the participants motivation to walk.

关键词： Legged locomotion Acceleration Robot motion Task analysis Training Turning"

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numerical simulation and analysis of lithium plasma during low-pressure DC arc discharge

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Plasma science and technology 2019年第4期21卷 16-21页

作者： Runhui WU Song CHAI Jiaqi LIU Shiyuan CONG Gang MENG National Key Laboratory of Science and Technology on Test Physics&Numerical Mathematics Beijing 100076People's Republic of China School of Physics Dalian University of TechnologyDalian 116024People's Republic of China

Alkali metal DC arc discharge has the characteristics of easy ionization,low power consumption,high plasma temperature and ionization degree,etc,which can be applied in aerospace vehicles in various *** this paper,we calculate the physical property parameters of lithium vapor,one of the major alkali metals,and analyze the discharge characteristics of lithium plasma with the magnetohydrodynamic(MHD)*** discharge effects between constant current and voltage sources are also *** is shown that the lithium plasma of DC arc discharge has relatively high temperature and current *** peak temperature can reach tens of thousands of K,and the current density reaches 6 x 107 A m *** the same rated power,the plasma parameters of the constant voltage source discharge are much higher than those of the constant current source discharge,which can be used as the preferred discharge mode for aerospace applications.

关键词： DC discharge lithium plasma numerical simulation low-pressure arc

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Automatic MHT Method Based on Target Characteristics Applied in the Small Space Targets 3

Automatic MHT Method Based on Target Characteristics Applied...

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3rd International Conference on Design, Mechanical and Material Engineering, D2ME 2018

作者： Zhao, Qian Niu, Zhenhong Xue, Lian Liu, Xin Li, Jianhua Li, Zhifeng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics China

The Multi-Hypothesis Tracking (MHT) method is one of the most promising approaches to realize automatic tracking of small and dim targets in complex space scene. However, the number of hypotheses generated by this algorithm has an exponentially increasing relationship with the number of trajectories, measurement data, and the number of image frames. In the paper, the automatic detection and tracking method of judging the confidence coefficient of the trajectory obtained by the MHT which is based on the characteristics of dim targets, has been realized in the IRST system. The performance of this method is greatly improved. © 2018 The Authors, published by EDP sciences.

关键词： Target tracking

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The Design of Large Arc-shape High-precision Walking Device in TV (thermal-vacuum) Conditions 3

The Design of Large Arc-shape High-precision Walking Device ...

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3rd International Conference on Design, Mechanical and Material Engineering, D2ME 2018

作者： Lian, Xue Hua, Nan Jiaqi, Liu Xin, Liu Gang, Meng National Key Laboratory of Science Technology on Test Physics and Numerical Mathematics China

The large-sized space environmental simulation test facility is mainly used for providing thermal radiation environment in high-vacuum, cold and dark space for satellites, spacecraft, lunar spacecraft to carry out whole satellite thermal vacuum test and for large equipment like antenna to carry out tests in TV conditions. Monitoring the spacecraft's surface optical image or temperature is a main task in space environment simulation test. In previous tests, optical image test mainly took place in a fixed position, so the measuring location and angle are limited. This paper focuses on large spherical space environmental simulation test facility, and designs a large arc-shape high-precision walking device in a space environment simulation test device. It introduces key technology in detail like structure design, thermal design, processes and manufacturing, etc. The test results show that this device can work steadily and reliably under simulation space environments, and the precision exceeds 0.5°. © 2018 The Authors, published by EDP sciences.

关键词： Design

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Nonlinear control algorithm for smooth transition in large-angle attitude maneuver

Nonlinear control algorithm for smooth transition in large-a...

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2011 International Conference on Recent Advancements in Electrical, Electronics and Control Engineering, IConRAEeCE'11

作者： Du, Runle Liu, Jiaqi Wang, Yonghai Meng, Gang Mu, Chenyang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics China

ISBN: (纸本)9781457721472

Large-angle attitude maneuver is common during the mission of spacecrafts, such as aligning to star to calibrate navigation system. Published works on attitude tracking always focus on optimizing the time and fuel cost, neglecting the smoothness requirement and angular speed limitations. In this paper, a nonlinear control algorithm is prompted for smooth transition in large-angle attitude maneuver. A nonlinear filter is added to the attitude feedback control loop, to carry out angular speed control in large-angle maneuvers. Simulation results demonstrated the effectiveness and reliability of proposed approach. © 2011 IEEE.

关键词： Navigation systems

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The Island Rule with lateral and bottom friction

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Acta Oceanologica Sinica 2019年第4期38卷 146-153页

作者： Yanzhao Yang Zexun Wei Guanlin Wang Zhan Lian Liwei Wang College of Meteorology and Oceanography National University of Defense Technology College of Mathematical Science and Physics Qingdao University of Science and Technology Key Laboratory of Marine Science and Numerical Modeling First Institute of OceanographyMinistry of Natural Resources Laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology (Qingdao)

The Island Rule, derived from the Sverdrup theory, is widely used to estimate and analyze water transport through a strait. Previous studies presented single-or multi-island rules with either lateral or bottom friction. In this paper,an analytical model of wind-driven circulation is assumed based on linear dynamics. Considering both lateral and bottom friction, the analytic solutions of the transport streamfunction around the islands are derived and the volume transport through the channel is presented. The results are similar to those of Wajsowicz, but the frictional constants represent different values. The analytic solution shows that the relationship between the lateral frictional and bottom frictional dissipation is complex in terms of the frictional constants. To understand the interaction between the two friction types, lateral and bottom friction values were randomly chosen on a barotropic beta plane. The result shows an approximately linear relationship between the lateral and bottom friction in consisting of the combined frictional constants. We studied the effect of the channel width on the transport through the channel. The results show that the friction enhances the flow under some widths, which is similar to the flow behavior when only the lateral friction is considered. We also compared the transport through the channel at different depths and founded that the deeper the water, the smaller the transport reduction ratio when the horizontal eddy viscosity coefficient and the bottom drag coefficient remained constants. To further present the combined role of lateral frictional and bottom frictional dissipation, we compared our model with the model of Wajsowicz for two islands, where only the lateral or bottom friction were considered, with different channel widths. The results showed that the effect of the lateral friction is greater than the bottom friction when the channel is narrow, especially in the Munk boundary layer thickness. When the channel is

关键词： Island Rule lateral friction bottom friction transport streamfunction

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A New Formation Mechanism of Counterstreaming Mass Flows in Filaments and the Doppler Bullseye Pattern in Prominences

arXiv

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arXiv 2025年

作者： Zhou, Chengrui Shen, Yuandeng Xia, Chun Liu, Dongxu Tang, Zehao Yao, Surui Yunnan Observatories Chinese Academy of Sciences Kunming650216 China School of Aerospace Harbin Institute of Technology Shenzhen518055 China Shenzhen Key Laboratory of Numerical Prediction for Space Storm Harbin Institute of Technology Shenzhen518055 China State Key Laboratory of Solar Activity and Space Weather National Space Science Center Chinese Academy of Sciences Beijing100190 China School of Physics and Astronomy Yunnan University Kunming650500 China University of Chinese Academy of Sciences Beijing100049 China

The eruption of solar prominences can eject substantial mass and magnetic field into interplanetary space and cause geomagnetic storms. However, various questions about prominences and their eruption mechanism remain unclear. In particular, what causes the intriguing Doppler bullseye pattern in prominences has not yet been solved, despite some preliminary studies proposing that they are probably associated with counterstreaming mass flows. Previous studies are mainly based on single-angle and short timescale observations, making it difficult to determine the physical origin of Doppler bullseye patterns in prominences. Here, taking advantage of stereoscopic observations taken by the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory and a three-dimensional numerical simulation, we investigate the origin of prominence Doppler bullseye pattern by tracing a long-lived transequatorial filament/prominence from July 23 to August 4, 2012. We find that repeated coronal jets at one end of the prominence can launch the Doppler bullseye pattern. It is evidenced in our observations and simulation that during the forward traveling of jet plasma along the helical magnetic field structure of the prominence, part of the ejecting plasma can not pass through the apex of the prominence due to the insufficient kinetic energy and therefore forms a backward-moving mass flow along the same or neighboring magnetic field lines. This process finally forms counterstreaming mass flows in on-disk filaments. When the on-disk filament rotates to the solar limb to be a prominence, the counterstreaming mass flows are naturally observed as a Doppler bullseye pattern. Copyright © 2025, The Authors. All rights reserved.

关键词： Plasma magnetohydrodynamic waves

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Online Tuning of Pre-trained Deep Neural Network for Guidance Against Non-cooperative Pursuer

Online Tuning of Pre-trained Deep Neural Network for Guidanc...

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2022 IEEE International Conference on Aerospace Electronics and Remote Sensing technology, ICARES 2022

作者： Du, Runle Shu, Yi Liu, Jiaqi Chen, Yang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (数字)9781665461917

ISBN: (纸本)9781665461917

In the astronautics, it is widely acknowledged as a hard problem that using neural network to handle the intelligent observation and guidance when dealing with non-cooperative pursuing vehicles. Due to the difficulty of obtaining training data set from non-cooperative vehicles, the inconsistency between training data and utilization data, application of neural network controller is by far very limited. In order to tackle this problem, an online tuning scheme of neural network is proposed in this paper aiming to boost the observation and counter action abilities against non-cooperative pursuer. In the proposed methodology, the deep neural network controller is pre-trained through dataset from generative network before deployment, and fine-tuned online through real time observations data set. In this way, the calculation pressure is alleviated for onboard computer and the contribution of real time observation data set is utilized more correctly, thus guaranteeing the efficiency and effectiveness of online tuning. Simulation results suggested that, both in the observation ability and counteractive guidance to avoid the pursuer, the proposed method all trumped traditional networks without online tuning, which resulting a higher chance to survive the pursuit. © 2022 IEEE.

关键词： Deep neural networks

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ISAR target micro-Doppler feature extraction and recognition method based on PCA and ICA

ISAR target micro-Doppler feature extraction and recognition...

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IET International Radar Conference 2015

作者： Bai, Jinliang Jiang, Zhiye Liu, Jiaqi Gao, Lu Liu, Hongyan Xu, Feng Qin, Peng Li, Hu Chen, Shuyuan Liu, Shengdong National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (纸本)9781849199940

Micro-Doppler features can be regarded as a unique signature of ISAR targets and provide critical information for target recognition. This paper proposes an ISAR micro-Doppler feature extraction and recognition method based on combination algorithm of principle component analysis (PCA) and independent component analysis (ICA). In order to decrease computation burden, PCA algorithm is first applied to reduce dimension and second order correlation, and then ICA decomposes micro-Doppler represented in time frequency domain into a set of independent basis components, which consist the micro-Doppler feature subspace. Target recognition is transformed to calculate the projection coefficient in the subspace. The experimental results verify the correctness and effectiveness of the proposed method.

关键词： Independent component analysis

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