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Journal of Thermal Science 2019年第4期28卷 736-744页

作者： WANG Lu MIAO Jianyin GONG Mingming ZHOU Qiangu LIU Changu ZHANG Hongxing FAN Hanlin Beijing key laboratory of Space Thermal Control Beijing 100094China Institute of Spacecraft system Engineering Beijing 100094China

An experimental research is conducted on the heat transfer characteristics of a loop heat pipe(LHP)used in the"mainline"heat transfer mode for spacecraft platform thermal *** heat from multiple instruments scattered in different locations is collected by thermal control techniques such as axially grooved heat pipes and then transmitted to the radiant surface for dissipation through the LHP in an unified *** research contents include the start-up characteristics,the operational stability characteristics,the operational blocking characteristics,the continuous blocking characteristics,the heat transfer capability,the thermal resistance,and the dynamic response characteristics under the change of the heat sink *** results show that the higher the auxiliary starting power is,the easier it is to start the LHP;the higher the input power of the thermoelectric cooler is,the more beneficial it is to speed up the stabilization of the vapor-liquid interface in the condenser;the higher the blocking power,the shorter the blocking time of the LHP;the LHP can be operated stably within the heat sink temperature alteration process;the heat transfer ability is higher than 500 W with a systematic thermal resistance of 0.037℃/W.

关键词： LHP mainline heat transfer mode heat transfer characteristics

Electromechanical Transient Modeling Analysis of Large-Scale New Energy Grid Connection

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Energy Engineering 2024年第4期121卷 1109-1125页

作者： Shichao Cao Yonggang Dong Xiaoying Liu Department of Electrical Engineering Hebei Vocational University of Technology and EngineeringXingtai054000China

The synchronous virtual machine uses inverter power to imitate the performance of the conventional synchronous *** also has the same inertia,damping,frequency,voltage regulation,and other external performance as the *** is the key technology to realize new energy grid connections’stable and reliable *** project studies a dynamic simulation model of an extensive new energy power system based on the virtual synchronous motor.A new energy storage method is *** mathematical energy storage model is established by combining the fixed rotor model of a synchronous virtual machine with the charge-discharge power,state of charge,operation efficiency,dead zone,and inverter *** rapid conversion of energy storage devices absorbs the excess instantaneous kinetic energy caused by *** branch transient of the critical cut set in the system can be confined to a limited ***,the virtual synchronizer’s kinetic and potential energy can be efficiently converted into an instantaneous *** simulation of power system analysis software package(PSASP)verifies the correctness of the theory and algorithm in this *** paper provides a theoretical basis for improving the transient stability of new energy-connected power grids.

关键词： New energy grid connection transient electromechanical modeling synchronous virtual machine PSASP software energy storage

Analysis of the coated and textured ring/liner conjunction based on a thermal mixed lubrication model

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Friction 2018年第4期6卷 420-431页

作者： Chunxing GU Xianghui MENG Di ZHANG State key laboratory of Mechanical system and Vibration Shanghai Jiaotong University School of Mechanical Engineering Shanghai Jiaotong University School of Mechanical Electronic technology Shanghai Jianqiao University

For the ring/liner conjunction, well‐designed surface texturing has been regarded as a potential means to improve its tribological performance, as well as the application of coating. However, so far most researchers focused on the one of these aspects. In this study, the combined effect of coating and texturing on the performance of ring/liner conjunction is numerically investigated. A thermal mixed lubrication model is presented. The effects of the coating's thermal and mechanical properties on the tribological performance are studied under the cold and warm engine operating conditions. Along with the increasing coating thickness, the effects of the coating's thermal properties on friction loss are found to be significant, as well as the effects of the coating's mechanical properties. It is also found that a soft coating with a lower thermal inertia has a greater ability to reduce the friction loss of the textured conjunction.

关键词： thermal mixed lubrication surface coating surface texturing piston ring tribological performance

Real-time recognition of human lower-limb locomotion based on exponential coordinates of relative rotations

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Science China(Technological Sciences) 2021年第7期64卷 1423-1435页

作者： XU Sen DING Ye State key laboratory of Mechanical system and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai200240China

This paper proposes a data-driven method using a parametric representation of relative rotations to classify human lower-limb locomotion, which is designed for wearable robots. Three Inertial measurement units(IMUs) are mounted on the subject's waist,left knee, and right knee, respectively. Features for classification comprise relative rotations, angular velocities, and waist acceleration. Those relative rotations are represented by the exponential coordinates. The rotation matrices are normalized by Karcher mean and then the Support Vector Machine(SVM) method is used to train the data. Experiments are conducted with a time-window size of less than 40 ms. Three SVM classifiers telling 3, 5 and 6 rough lower-limb locomotion types respectively are trained, and the average accuracies are all over 98%. With the combination of those rough SVM classifiers, an easy SVMbased ensembled-system is proposed to classify 16 fine locomotion types, achieving the average accuracy of 98.22%, and its latency is 18 ms when deployed to an onboard computer.

关键词： locomotion recognition exponential coordinate relative rotation support vector machine

A relay selection scheme based on geometric optimum in cooperative cognitive systems over mixed channels

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High technology Letters 2013年第3期19卷 321-326页

作者：李静叶 Luo Tao Shao Yubin Yue Guangxin Beijing key laboratory of Network system Architecture and Convergence Beijing University of Posts and Telecommunications School of Information Engineering and Automation Kunming University of Science and Technology

This paper proposes a relay selection scheme based on geometric optimum principle to maximize the cognitive link＇ s connectivity with limited interference to primary user in cooperative cognitive systems. A dual-hop cognitive relay system is considered, in which the channel impulse response follows independent non-identical distribution （i. n. d. ） each hop, such as Rician, Rayleigh and Nakagami-m distribution. Then, closed-form expressions in terms of outage probability and average bit error rate （ABER） are obtained using amplify-and-forward （AF） relaying protocol over such mixed fading channels. Furthermore, the best range of the relay is derived. Extensive simulation re- suits are conducted to verify the theoretical analysis, which is useful to the network optimal design.

关键词： cognitive radio (CR) relay outage probability average bit error rate (ABER) mixed channels

Fault Tolerance Mechanism in Chip Many-Core Processors

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Tsinghua Science and technology 2007年第S1期12卷 169-174页

作者：张磊韩银和李华伟李晓维 key laboratory of Computer system and Architecture Institute of Computing TechnologyChinese Academy of Sciences Graduate University of Chinese Academy of Sciences Beijing 100080China

As semiconductor technology advances, there will be billions of transistors on a single chip. Chip many-core processors are emerging to take advantage of these greater transistor densities to deliver greater performance. Effective fault tolerance techniques are essential to improve the yield of such complex chips. In this paper, a core-level redundancy scheme called N+M is proposed to improve N-core processors’ yield by providing M spare cores. In such architecture, topology is an important factor because it greatly affects the processors’ performance. The concept of logical topology and a topology reconfiguration problem are introduced, which is able to transparently provide target topology with lowest performance degradation as the presence of faulty cores on-chip. A row rippling and column stealing (RRCS) algorithm is also proposed. Results show that PRCS can give solutions with average 13.8% degradation with negligible computing time.

关键词： chip many-core processors yield fault tolerance reconfiguration network-on-chip

Modeling porous structure of oil-pressboard interface and its effect on electric field distribution

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Journal of Central South University 2015年第1期22卷 338-343页

作者：司马文霞姜赤龙毛文奇唐信 State key laboratory of Power Equipment & system Security and New technology(Chongqing University) State Grid Hunan Electric Power Corporation Maintenance Company State Grid Hunan Electric Power Corporation

The oil-pressboard insulation is a typical composite insulation system widely used in the design and manufactory of large power apparatus. The implement of oil-pressboard insulation may lead to surface electrification and discharge at the interface under certain condition. It is of significant importance to take an insight into the phenomenon occurring at the interface. Through experiment, the pressboard is found as a porous material. The interface changes abruptly from bulk pressboard to the bulk oil as a result of the porous structure. A new model is proposed which divides the interface into bulk oil region, transition region, and bulk pressboard region. The width of the transition region is decided according to the microtome figure. The effective permittivity of the transition region is calculated using a new model based on fractal theory. The model is validated and compared with previous calculation model. The effect of the existence of transition region on the electric field distribution is discussed.

关键词： oil-pressboard interface transition region effective permittivity fractal electric field distribution

Temperature-dependent optical response of phase-only nematic liquid crystal on silicon devices

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Chinese Optics Letters 2016年第11期14卷 85-89页

作者：张紫辰 Huan Xu 杨海宁尤政初大平 Institute of microelectronics Chinese Academy of Sciences Electrical Engineering Division Department of EngineeringUniversity of Cambridge State key laboratory of Precision Measurement technology and Instruments Collaborative Innovation Center for Micro/Nano FabricationDevice and System Department of Precision Instrument Tsinghua University

Wavelength-dependent birefringence and dielectric *** major optical properties of the nematie liquid crystal materials used in phase-only liquid crystal on silicon（LCOS） devices,are measured as a function of operating *** dynamic phase modulation depth and threshold voltage of these phase-only LCOS devices are also measured in the corresponding temperature range and compared with theoretical *** results show that the dynamic response time can he reduced significantly by an appropriate increase ol device operative temperature,while the necessary device elements,such as phase modulation depth and threshold voltage,can be maintained at the same time.

关键词： Birefringence Dielectric materials Display devices Liquid crystals Liquids Modulation Optical properties Phase modulation Threshold voltage

Intertidal area classification with generalized extreme value distribution and Markov random field in quad-polarimetric synthetic aperture radar imagery

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Frontiers of Information technology & Electronic Engineering 2019年第2期20卷 253-264页

作者： Ting-ting JIN Xiao-qiang SHE Xiao-lan QIU Bin LEI key laboratory of technology in Geo-spatial Information Processing and Application system Institute of ElectronicsChinese Academy of Sciences University of Chinese Academy of Sciences Huawei Software Technologies Co. Ltd.

Classification of intertidal area in synthetic aperture radar(SAR) images is an important yet challenging issue when considering the complicatedly and dramatically changing features of tidal fluctuation. The difficulty of intertidal area classification is compounded because a high proportion of this area is frequently flooded by water, making statistical modeling methods with spatial contextual information often ineffective. Because polarimetric entropy and anisotropy play significant roles in characterizing intertidal areas, in this paper we propose a novel unsupervised contextual classification algorithm. The key point of the method is to combine the generalized extreme value(GEV) statistical model of the polarization features and the Markov random field(MRF) for contextual smoothing. A goodness-of-fit test is added to determine the significance of the components of the statistical model. The final classification results are obtained by effectively combining the results of polarimetric entropy and anisotropy. Experimental results of the polarimetric data obtained by the Chinese Gaofen-3 SAR satellite demonstrate the feasibility and superiority of the proposed classification algorithm.

关键词： Intertidal classification Polarimetric synthetic aperture radar Finite mixture model Markov random field Generalized extreme value model

Design and Experimental Validation of a Worm-Like Tensegrity Robot for In-Pipe Locomotion

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Journal of Bionic Engineering 2023年第2期20卷 515-529页

作者： Xiaolin Dai Yixiang Liu Wei Wang Rui Song Yibin Li Jie Zhao School of Control Science and Engineering Shandong UniversityJinan250061China Engineering Research Center of Intelligent Unmanned system of Ministry of Education Jinan250061China Shandong Research Institute of Industrial technology Jinan250061China State key laboratory of Robotics and system Harbin Institute of TechnologyHarbin150080China

Traditional rigid-body in-pipe robots usually have complex and heavy structures with limited flexibility and *** soft in-pipe robots have great improvements in flexibility,they still have manufacturing difficulties due to their reliance on high-performance soft *** structure is a kind of self-stressed spatial structure consisting discrete rigid struts connected by a continuous net of tensional flexible strings,which combines the advantages of both rigid structures and soft *** applying tensegrity structures into robotics,this paper proposes a novel worm-like tensegrity robot for moving inside ***,a robot module capable of body deformation is designed based on the concept of tensegrity and its deformation performance is ***,the optimal parameters of the module are obtained based on the tensegrity *** deformation ability of the tensegrity module is tested ***,the worm-like tensegrity robot that can crawl inside pipes is developed by connecting three modules in *** performance and load capacity are tested on the prototype of the worm-like tensegrity robot by experiments of moving in horizontal pipe,vertical pipe,and elbow *** results demonstrate the effectiveness of the proposed design and suggest that the robot has high compliance,mobility,and adaptability although with simple structure and low cost.

关键词： Bio-inspired robot Soft robot application Tensegrity structure Pipe crawling