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Analytical long-term evolution and perturbation compensation models for BeiDou MEO satellites

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Chinese Journal of Aeronautics 2018年第2期31卷 330-338页

作者： Li FAN min hu Chao JIANG School of Aerospace Engineering Tsinghua University Beijing 100084 China Space Engineering University Beijing 101416 China College of Aerospace Science and Engineering National University of Defense Technology Changsha 410073 China

The current paper establishes the analytical models of the long-term evolution and perturbation compensation strategy for Medium Earth Orbits（MEO）shallow-resonant navigation constellation,with application to the Chinese Bei Dou Navigation Satellite System（BDS）.The long-term perturbation model for the relative motion is developed based on the Hamiltonian model,and the long-term evolution law is *** relationship between the control boundary of the constellation and the offset of the orbital elements is analyzed,and a general analytical method for calculating the offset of the orbit elements is *** analytical model is further improved when the luni-solar perturbations are *** long-term evolutions of the BDS MEO constellation within 10 years are illustrated,and the effectiveness of the proposed analytical perturbation compensation calculation approach is compared with the traditional numerical *** found the fundamental reason for the nonlinear variations of the relative longitude of ascending node and the mean argument of latitude is the long-periodic variations of the orbital inclination due to the luni-solar *** proposed analytical approach can avoid the numerical iterations,and reveal the essential relationship between the orbital element offsets and the secular drifts of the constellation ***,there is no need for maintaining the BDS MEO constellation within 10 years while using the perturbation compensation method.

关键词： BeiDou Navigation Satellite System (BDS) Long-term evolution Luni-solar perturbations Medium Earth Orbits(MEO) Perturbation compensation

Nonlinear Evolutions of Stimulated Raman and Brillouin Scattering Processes in Partially Stripped-Ion Plasmas

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Chinese Physics Letters 2001年第9期18卷 1230-1233页

作者： hu Ye-min hu Xi-Wei Departmentof Electrical Engineering Huazhong University of Science and TechnologyWuhan 430074 Department of Modern Physics University of Science and Technology of ChinaHefei 230026

Numerical analyses for the nonlinear evolutions of stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) processes are given. Various effects of the second- and third-order nonlinear susceptibilities on the SRS and SBS processes are studied. The nonlinear evolutions of SRS and SBS processes are atfected more efficiently than their linear growth rates by the nonlinear susceptibility.

关键词： Brillouin nonlinear Nonlinear

Consensus Control With a Constant Gain for Discrete-time Binary-valued Multi-agent Systems Based on a Projected Empirical Measure Method

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IEEE/CAA Journal of Automatica Sinica 2019年第4期6卷 1052-1059页

作者： Ting Wang min hu Yanlong Zhao IEEE the Key Laboratory of Systems and Control Institute of Systems ScienceAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China the School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100149China

This paper studies the consensus control of multiagent systems with binary-valued *** algorithm alternating estimation and control is *** agent estimates the states of its neighbors based on a projected empirical measure method for a holding *** on the estimates,each agent designs the consensus control with a constant gain at some skipping *** states of the system are updated by the designed control,and the estimation and control design will be *** the estimation,the projected empirical measure method is proposed for the binary-valued *** algorithm can ensure the uniform boundedness of the estimates and the mean square error of the estimation is proved to be at the order of the reciprocal of the holding time(the same order as that in the case of accurate outputs).For the consensus control,a constant gain is designed instead of the stochastic approximation based gain in the existing literature for binary-valued ***,there is no need to make modification for control since the uniform boundedness of the estimates ensures the uniform boundedness of the agents’***,the systems updated by the designed control are proved to achieve consensus and the consensus speed is faster than that in the existing *** are given to demonstrate the theoretical results.

关键词： Binary-valued observations consensus control constant gain convergence rate multi-agent systems projected empirical measure method

DYNAMIC CVAR WITH MULTI-PERIOD RISK PROBLEMS

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Journal of Systems Science & Complexity 2011年第5期24卷 907-918页

作者： Zhiqing MENG min JIANG Qiying hu College of Business and Administration Zhejiang University of Technology Hangzhou 310023 China School of Management Fudan University Shanghai 200433 China

This paper studies multi-period risk management problems by presenting a dynamic risk measure. This risk measure is the sum of conditional value-at-risk of each period. The authors model it by Markov decision processes and derive its optimality equation. This equation is further transformed equivalently to an analytically tractable one. The authors then use the model and its results to a multi-period portfolio optimization when the return rate vectors at each period form a Markov chain.

关键词： α-CVaR multi-period optimality equation optimal policy.

Impact of Typical Steady-state Conditions and Transient Conditions on Flow Ripple and Its Test Accuracy for Axial Piston Pump

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 1012-1022页

作者： XU Bing hu min ZHANG Junhui State Key Laboratory of Fluid Power Transmission and Control Zhejiang University

The current research about the flow ripple of axial piston pump mainly focuses on the effect of the structure of parts on the flow ripple. Therein, the structure of parts are usually designed and optimized at rated working conditions. However, the pump usually has to work in large-scale and time-variant working conditions. Therefore, the flow ripple characteristics of pump and analysis for its test accuracy with respect to variant steady-state conditions and transient conditions in a wide range of operating parameters are focused in this paper. First, a simulation model has been constructed, which takes the kinematics of oil film within friction pairs into account for higher accuracy. Afterwards, a test bed which adopts Secondary Source Method is built to verify the model. The simulation and tests results show that the angular position of the piston, corresponding to the position where the peak flow ripple is produced, varies with the different pressure. The pulsating amplitude and pulsation rate of flow ripple increase with the rise of pressure and the variation rate of pressure. For the pump working at a constant speed, the flow pulsation rate decreases dramatically with the increasing speed when the speed is less than 27.78% of the maximum speed, subsequently presents a small decrease tendency with the speed further increasing. With the rise of the variation rate of speed, the pulsating amplitude and pulsation rate of flow ripple increase. As the swash plate angle augments, the pulsating amplitude of flow ripple increases, nevertheless the flow pulsation rate decreases. In contrast with the effect of the variation of pressure, the test accuracy of flow ripple is more sensitive to the variation of speed. It makes the test accuracy above 96.20% available for the pulsating amplitude of pressure deviating within a range of ~6% from the mean pressure. However, with a variation of speed deviating within a range of ±2% from the mean speed, the attainable test accuracy o

关键词： axial piston pump flow ripple test accuracy steady-state condition transient condition wide operating ranges

Using FEM to predict tree motion in a wind field

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第7期9卷 907-915页

作者： Xiao-yi hu Wei-ming TAO yi-mu GUO Department of Mechanical Engineering Zhejiang University Hangzhou 310027 China School of Engineering Zhejiang Forestry University Hangzhou 311300 China

In this paper we propose a finite element(FE) simulation method to predict tree motion in a wind field. Two FE tree models were investigated:One model was generated based on a realistic nature-looking geometric tree model,and the other was a symmetric model to investigate the influence of asymmetric material properties on tree motion. The vortex-induced vibration(VIV) theory is introduced to estimate the fluctuating wind force being exerted on tree stems and the fluid-structure interaction(FSI) analysis is also included in the simulation. The results indicate that asymmetric material properties result in the crosswind displacement of the investigated node and the main swaying direction deviation. The simulation reveals that under wind loading,a tree with leaves has much larger swaying amplitude along the wind direction and longer swaying period than a tree without leaves. However,the crosswind swaying amplitude is mainly due to branch interaction. The numerical simulation proved that the inter-action of tree branches can prevent dangerous swaying motion developing.

关键词： Finite element method (FEM) Fluid-structure interaction (FSI) Vortex-induced vibration (VIV) Asymmetric Wind field

The spike layer solution to singular perturbation Robin boundary value problem for higher order elliptic equation

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Applied Mathematics(A Journal of Chinese Universities) 2020年第4期35卷 410-416页

作者： FENG yi-hu HOU Lei Department of Mathematics Shanghai UniversityShanghai 200444China

The singularly perturbed Robin boundary value problem for the higher order elliptic equation is *** suitable conditions,the existence and asymptotic behavior of solution to the boundary value problems are *** uniform ... 详细信息

关键词： nonlinear Robin problem spike layer

Systematic analysis of microfauna indicator values for treatment performance in a full-scale municipalwastewater treatment plant

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Journal of Environmental Sciences 2013年第7期25卷 1379-1385页

作者： Bo hu Rong Qi min Yang State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences

The indicator values of microfauna functional groups and species for treatment performancewere systematically evaluated based on the continuous monitoring of the entire microfauna communities including both protozoa and metazoa over a period of 14 months, in two parallel full-scale municipalwastewater treatment systems in a plant in Beijing, China. A total of 57 species of ciliates, 14 species （units） of amoebae, 14 species （units） of flagellates and4 classes of small metazoawere identified,with Arcella hemisphaerica, Vorticella striata, Vorticella convallaria, Epistylis plicatilis and small flagellates （e.g. Bodo spp.） as thedominant protozoa, and rotifers as thedominant metazoa. The abundance of the sessile ciliateswas correlatedwith the removals of BOD 5 （Pearson＇s r = 0.410, p 〈 0.05） and COD Cr （r = 0.397, p 〈 0.05）while the testate amoebaewas significantly positively related to nitrification （r = 0.523, p 〈 0.01）. At the same time, some other associationswere also identified： the abundances of the large flagellates （r = 0.447, p 〈 0.01）, the metazoa （r = 0.718, p 〈 0.01） and species Aspidisca sulcata （r = 0.337, p 〈 0.05）were positively related to nitrification; the abundance of Aspidisca costatawas correlated to the TN （total nitrogen） removal （r = -0.374, p 〈 0.05 ）; the abundances of the sessile species Carchesium polypinum （r = 0.458, p 〈 0.01） and E. plicatilis （r = 0.377, p 〈 0.05）were correlatedwith the removal of suspended solids.

关键词： protozoan metazoan activated sludge treatment performance bioindicator

THE CONDITIONAL DIAGNOSABILITY OF ShuFFLE-CUBES

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Journal of Systems Science & Complexity 2010年第1期23卷 81-90页

作者： min XU Xiaodong hu Songpu SHANG School of Mathematical Sciences Beijing Normal University Laboratory of Mathematics and Complex Systems Ministry of Education Beijing 100875 China Institute of Applied Mathematics MADIS Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China College of Mathematics and Information Science North China University of Water Conservancy and Electric Power Zhengzhou Henan 450008 China

In the application of multiple-processor systems some processors or links in a system maynot function properly,thus the fault diagnosis is one of the most important issues in the analysisand maintenance of those *** the practical fault diagnosis systems,the probability that allneighboring processors of a processor are faulty simultaneously is very ***,the conditionaldiagnosability,which is a new metric for evaluating such systems,assumes that every fault set doesnot contain all neighbors of any processor in the *** this paper,the authors show that then-dimensional shuffle-cube has the conditional diagnosability of 4n-15 for n = 2 (mod 4) and n ≥ 10.

关键词： Conditional diagnosability fault diagnosis shuffle-cubes.