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Research of Favorable Conversion of Friction during Powder Compaction

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Research of Favorable Conversion of Friction during Powder C...

第五届国际材料与热加工物理模拟及数值模拟学术会议

作者： WANG De-guang1a WU Yu-cheng1b JIAO Ming-hua2 XIE Ting2 YU Jian-wei2 YIN Yan-guo2 1School of Material and engineering Hefei university of technology Anhui Hefei 230009 2institute of tribology Hefei university of technology Anhui Hefei 230009

The warm powder compaction process is simulated by the finite element analysis software which is MSC/MARC. The thermal mechanically coupled analysis method is applied based on the updated Lagrangian Method to study the influence of different velocities ratio of die and punch υdie/υup-punch on the properties of green under different frictional condition. The results indicate that for cylindrical powder metallurgic products, different velocity ratios have great influence on the distribution of relative density and equivalent stress. The frictional force can be converted to the favorable force through adjusting the velocity ratio, and this method can obtain higher uniform distribution of relative density and stress of green.

关键词： powder density FE property compaction friction

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随机Petri网对可修复系统的建模和分析

天津大学学报（自然科学与工程技术版） 2004年第3期37卷 258-263页

作者：孙俊清王鹏涛于长云南开大学信息技术科学学院天津300071 天津理工学院计算机系天津300191

为分析工程中较大的可修复系统的工作状态、可靠性和修理工的工作强度,提出了一类由不同机器和具有混合技能的不同维修人员所组成的可修复系统,引进了状态转移是Markov过程的随机Petri网,对系统进行建模,通过实例分析系统的状态空间、... 详细信息

为分析工程中较大的可修复系统的工作状态、可靠性和修理工的工作强度,提出了一类由不同机器和具有混合技能的不同维修人员所组成的可修复系统,引进了状态转移是Markov过程的随机Petri网,对系统进行建模,通过实例分析系统的状态空间、各状态在稳态下的期望频率、期望持续时间、系统的可靠性和维修人员的工作强度,分析了随机C/E网和随机P/T的适用范围.与传统的状态空间法相比较,在确定可修复系统的状态空间、分析状态间的逻辑关系和系统的动态过程中,随机Petri网具有显著的有效性和优越性.

关键词：随机Petri网可修复系统 Markov过程建模离散事件动态系统

GNSS Constellation State Probability Analysis Based on Markov Chain

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GNSS Constellation State Probability Analysis Based on Marko...

第三届中国卫星导航学术年会

作者： Li Zuo-hu1,2, Jiao Wen-hai2, Wu Hai-ling2, Hao Jin-ming1, Zhao Qi-le3, Li Jian-wen1,3 1. institute of Surveying and Mapping, Information engineering university, Zhengzhou, china 2. Beijing institute of Tracking and Telecommunication technology, Beijing, china 3. Research Center of GNSS, Wuhan university, Wuhan, china

Satellite navigation system is an integrated system program and reliability theory and method have become an important tool in GNSS performance evaluation. At first, this paper analyzes the failure mode and backup strategy that have impacts on constellation state probability. Time homogenous Markov chain is adopted to represent the change of state of GNSS constellation and a constellation state probability oriented Markov chain equation is also derived. To obtain an initial state of the constellation, a comprehensive and equivalent method for different constellation failure modes is probed into. In addition, based on empirical data of GPS failure modes, this paper conducts a research on the impact of failure mode and constellation backup strategy on the constellation state probability un- der two different initial states. The results demonstrate that the impacts of failure mode on constellation state probability differ under different initial states while those of the failure parameters are all alike. And compared with increased MTBF, reduced MTTR can evidently improve the constellation state probability. There is nearly no impact of backup strategy on constellation state probability. The more backup satellites there are, however, the more available constellations there will be. For a 24-satellite nominal constellation, maintaining more than three satellites can ensure a reasonable amount of available satellites within a year.

关键词： Markov chain GNSS Constellation State Probability Failure mode

The Improved Algorithm of UPF in Spacecraft Autonomous Optical Navigation

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The Improved Algorithm of UPF in Spacecraft Autonomous Optic...

第二十七届中国控制会议

作者： Du Junwei 1,Sui Shulin 2,Yao wenlong 2 1.College of Information Science and technology,Qingdao university of Science & technology,Qingdao 266042,P.R.china 2.institute of Autonomous Navigation and Intelligent Control,Qingdao university of Science and technology,Qingdao 266042,P.R.china

An autonomous optical navigation scheme for cruise phase is presented using the star light data and body edge data which is measured by star sensor and optical navigation *** the relative position for probes is acquired from the star light data and body edge *** observation information is pretreated by wavelet analysis and filter the high frequency noise,then uses the wavelet to recompose the signal to gain smooth parameters value and makes a process of UPF（Unscented Particle Filter） based on these work,so as to reduce the variance of importance *** real time orbit for probes is determined by using *** arithmetic integrates wavelet analysis and UPF to improve the precise and reliability of the autonomous optical navigation *** result shows that the improved UPF algorithm is not only more accurate but also has higher rate of convergence compared with the UPF.

关键词： Autonomous optical navigation Unscented particle filter Kalman filter Wavelet analysis

Design of Integrated Navigation System Based on Information Fusion technology

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Design of Integrated Navigation System Based on Information ...

第二十四届中国控制会议

作者： Chunmei Huang~(1,2), Yantao Tian~1, Wanxin Su~3, Yuhua Wang~2(1. School of Communications, Jilin university, Changchun 130022 china) 2. Changchun university of technology, Changchun 130012 3. Changchun institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun 130033

With the rapidly development of science and technology. The single navigation system for positioning and orientating is not adequate for the requirement of navigation, position, and orientation in the field of military and civil. The higher precision and cheaply cost of integrated navigation system are gradually applied for every field. Therefore, the combination of GPS and INS constitute the integrated navigation system becoming a developmental direction. This thesis discusses the technology problem and calculation methods of GPS/GLONASS/INS integrated navigation system. Firstly, it summarizes the merit and demerit of GPS and INS navigation system respectively. Putting forward the GPS/GLONASS/INS integrated navigation system based on information fusion technology. Also, a new method of GPS/GLONASS/INS integrated navigation system for quick positioning and orientating is presented, on the basis of which the scheme and the principles are given. Then a multi-sensor information fusion algorithm based on federal kalman filter is analyzed in detail. Finally, the computer simulation is given. The results show that federal kalman filter can deal with information fusion for the GPS/GLONASS/INS integrated system. Efficiently improving the accuracy and the reliability of the navigation system. It is the best way for seeking the navigation parameter and lead to the GPS/GLONASS/INS integrated system acquiring superior performance.

关键词： GPS INS information fusion integrated navigation federal Kalman filter

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最优化技术的高速叉车车身转动惯量辨识方法

系统仿真学报 2009年第16期21卷 5072-5074,5079页

作者：王勇丁渭平何森东总后勤部建筑工程研究所西安710032 西南交通大学机械工程学院成都610031

针对某型高速叉车底盘与车身匹配分析的虚拟样机,为确保其仿真分析的置信度,依托整车平顺性测试结果,采用最优化技术辨识车身转动惯量并用于虚拟样机的修正。具体地,一方面,由整车平顺性测试结果中获得其前、后悬架系统悬挂质量部分的... 详细信息

针对某型高速叉车底盘与车身匹配分析的虚拟样机,为确保其仿真分析的置信度,依托整车平顺性测试结果,采用最优化技术辨识车身转动惯量并用于虚拟样机的修正。具体地,一方面,由整车平顺性测试结果中获得其前、后悬架系统悬挂质量部分的固有频率,即偏频。另一方面,将车身转动惯量视为参数化变量,建立参数化的车身振动分析之理论模型。进而,基于理论模型计算而再次得到前、后悬架系统偏频,并优化车身转动惯量的参数化取值,最终使悬架偏频的理论计算结果与相应的测试结果趋于吻合,此时的车身转动惯量取值即为最终的辨识结果,由此大大提高了这一建模所需关键性基础数据的精确性。而相关的整车动态测试结果则验证了所提方法的有效性。

关键词：高速叉车虚拟样机车身转动惯量辨识

Screening of low-friction two-dimensional materials from highthroughput calculations using lubricating figure of merit

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Friction 2024年第8期12卷 1897-1908页

作者： Kewei TANG Weihong QI Guoliang RU Weimin liu State Key Laboratory of Solidification Processing and Center of Advanced Lubrication and Seal Materials Northwestern Polytechnical UniversityXi’an 710072China Shandong Laboratory of Yantai Advanced Materials and Green Manufacturing Yantai 265503China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Two-dimensional materials are excellent lubricants with inherent ***,superlubricity has been reported for only a few of these ***,other promising two-dimentional(2D)materials with different physical properties cannot be discovered or applied in production;thus,energy consumption can be greatly ***,we carry out high-throughput calculations for 1,4752D materials and screen for low-friction *** set a standard,we propose,for the first time,a geometry-independent lubricating figure of merit based on the conditions for stick-slip transition and our theory of Moiré*** the efficient calculation of this figure of merit,an innovative approach was developed based on an improved registry index *** calculations,340 materials were found to have a figure of merit lower than 10−***,a small set of 21 materials with a figure of merit lower than 10−4 were screened *** materials can provide diverse choices for various *** addition,the efficient computational approach demonstrated in this work can be used to study other stacking-dependent properties.

关键词： two-dimensional materials high-throughput calculation tribology low-friction materials Moirépatterns

Study on step friction characteristic of young people and children

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Study on step friction characteristic of young people and ch...

china 6th International Symposium on tribology

作者： Jia LIxiao~(1 2) Zhang Yongzhen~1 Niu Yongping~1 Du Sanming~(1 3) 1 Key Laboratory of Material tribology Henanuniversity of Science and technology 471003 2 Department of Mechanical &Electrical engineering Luoyang institute of Science and technology 471023 3 State Key Laboratory of Solid Lubrication Lanzhou institute of Chemical Physics 730000

＜正＞*** Accidents caused by slips and falls are serious safety problems in many countries[1,2]. generally,slip possibility was decided by step characteristic while *** frictional characteristics of the shoe and the ...

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Integrated Survivability Strategies of IP/GMPLS/Optical Multi-layer Network

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Semiconductor Photonics and technology 2003年第3期9卷 141-147页

作者： ZHAO Ji jun 1,2 , JI Yue feng 1, XU Da xiong 1 (1. Opt.Commun.Center,Beijing university of Posts and telecommunications,Beijing 100876,CHN 2. Hebei institute of Architectural Science and technology, Handan 056038, CHN) Opt. Coinmun. Center Beijing University of Posts and telecommunications 北京 100876

In last decade,due to that the popularity of the internet, data-central traffic kept growing,some emerging networking requirements have been posed on the todays telecommunication networks,especially in the area of network ***,as a key networking problem,network reliability will be more and more *** integration of different technologies such as ATM,SDH,and WDM in multilayer transport networks raises many questions regarding the coordination of the individual network *** problem is referred as multilayer network *** integrated multilayer network survivability is investingated as well as the representation of an interworking strategy between different single layer survivability schemes in IP via generalized multi-protocol label switching over optical network.

关键词： optical network multilayer survivability GMPLS