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移动容迟网络中基于改进随机路点模型的移动连接路由

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吉林大学学报（工学版） 2011年第S1期41卷 297-303页

作者：李晖浙江大学航空航天学院杭州310027

在移动容迟网络中,考虑到稀疏网络节点混存长时间被无效消息占用情况,将移动连接路由算法与倒数计时器和快速缓存释放策略相结合,提出了加速缓存释放的移动连接路由算法,并研究了节点移动速率、通信距离、节点数量、消息有效时间、场景... 详细信息

在移动容迟网络中,考虑到稀疏网络节点混存长时间被无效消息占用情况,将移动连接路由算法与倒数计时器和快速缓存释放策略相结合,提出了加速缓存释放的移动连接路由算法,并研究了节点移动速率、通信距离、节点数量、消息有效时间、场景尺寸等对算法性能的影响。结果表明:该路由算法在保证传输可靠性的前提下能够提高网络的传输效率。

关键词：通信技术移动延迟网络随机路点模型路由缓存释放

ROBUST NONPARAMETRIC REGRESSION BASED ON L_1-NORM AND B-SPLINES

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Systems Science and Mathematical Sciences 1995年第2期8卷 187-192页

作者： SHI Peide(Department of Probability and Statistics, Peking univ.rsity, Beijing 100871,china)ZHANG Zhengjun(school Of Management,Beijing univ.rsity of aeronautics and astronautics,Beijing 100083, china) 北京大学概率统计系北京北京航空航天大学管理学院北京

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ＲＯＢＵＳＴＮＯＮＰＡＲＡＭＥＴＲＩＣＲＥＧＲＥＳＳＩＯＮＢＡＳＥＤＯＮＬ＿１－ＮＯＲＭＡＮＤＢ－ＳＰＬＩＮＥＳＳＨＩＰｅｉｄｅ（ＤｅｐａｒｔｍｅｎｔｏｆＰｒｏｂａｂｉｌｉｔｙａｎｄＳｔａｔｉｓｔｉｃｓ，ＰｅｋｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎ...

关键词： B-spline function L1-norm estimator TURBO nonparametric regression

Formation control for networked spacecraft in deep space:with or without communication delays and with switching topology

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Science china(Information Sciences) 2011年第3期54卷 469-481页

作者： WANG Nan 1,2, ZHANG TianWu 2 & XU JieQiong 1 1 school of Aeronautic Science and Engineering, Beijing univ.rsity of aeronautics and astronautics, Beijing 100191, china 2 Department of Computer Science and Engineering, Henan Institute of Engineering, Zhengzhou 451191, china 1. school of Aeronautic Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China2. Department of Computer Science and Engineering Henan Institute of Engineering Zhengzhou 451191 China

In this paper, several formation controllers are developed with constant and variable connected communication topology for six-degree-of-freedom (6-DOF) networked spacecraft flying in deep space with constant and time-varying communication delays considered. In the control algorithm, any explicit leader does not exist in the formation team and it is required that each spacecraft communicate only with its neighbors and therefore the required communication loads of the whole formation is greatly reduced. The proposed control strategies allow that each spacecraft can track its desired position and attitude and simultaneously the whole group moves to the desired formation and obtain its desired relative attitudes with its neighbors. Simulation results demonstrate the effectiveness of the proposed controllers.

关键词： deep space graph theory formation control communication topology delays

An exploration for the macroscopic physical meaning of entropy

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Science china(Technological Sciences) 2010年第7期53卷 1809-1816页

作者： WU Jing1 & GUO ZengYuan2 1 College of Energy and Power Engineering, Nanjing univ.rsity of aeronautics and astronautics, Nanjing 210016, china 2 Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, school of Aerospace, Tsinghua univ.rsity, Beijing 100084, china 1. College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education School of Aerospace Tsinghua University Beijing 100084 China

The macroscopic physical meaning of entropy is analyzed based on the exergy (availability) of a combined system (a closed system and its environment), which is the maximum amount of useful work obtainable from the system and the environment as the system is brought into equilibrium with the environment. The process the system experiences can be divided in two sequent sub-processes, the process at constant volume, which represents the heat interaction of the system with the environment, and the adiabatic process, which represents the work interaction of the system with the environment. It is shown that the macroscopic physical meaning of entropy is a measure of the unavailable energy of a closed system for doing useful work through heat interaction. This statement is more precise than those reported in prior literature. The unavailability function of a closed system can be defined as T0S and p0V in volume constant process and adiabatic process, respectively. Their changes, that is, AiTgS) and A (p0V) represent the unusable parts of the internal energy of a closed system for doing useful work in corresponding processes. Finally, the relation between Clausius entropy and Boltzmann entropy is discussed based on the comparison of their expressions for absolute entropy.

关键词： entropy macroscopic physical meaning exergy heat interaction

Influences of Laser Powers on Microstructure and Properties of the Al-Si/Al+Al_2O_3 Coating on the AZ91D Magnesium Alloy

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稀有金属材料与工程 2011年第S4期40卷 226-230页

作者： Qian Jiangang1,Zhang Jiaxiang1,2,Li Shuqing2,Wang Chun2,Gong Shuili21school of Chemistry and Environment,Beijing univ.rsity of aeronautics and astronautics,Beijing 100191,china2Science and technology on Power Beam Processes Laboratory,Avic Beijing Aeronautical Manufacturing technology Research Institute,Beijing 100024,china Beijing univ Aeronaut & Astronaut Sch Chem & Environm Beijing 100191 Peoples R China Avic Beijing Aeronaut Mfg Technol Res Inst Sci & Technol Power Beam Proc Lab Beijing 100024 Peoples R China

An Al-Si/Al+Al2O3 coating was prepared on an AZ91D Mg alloy substrate by laser cladding of the plasma-sprayed coating.X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the phases and to study the morphology,*** adhesion strength and the porosity ratio of the coating were measured by using a tensile testing machine and an optical microscope (OM),*** microhardness was measured using a micro Vickers hardness *** results show that after laser cladding,the adhesion strength of the coating increased from 10.78 to 25.17 *** the laser power was 1400W,the metastable γ-Al2O3 phase in the coating transformed completely into the stable α-Al2O3 *** with the increase of the laser power,the porosity ratio of the coating *** when the laser power was over 1400W,the porosity ratio *** microhardness of the surface was the hardest which was improved from HV0.05125 to *** larger the power of the laser was,the harder the coating *** when the power was 1600W,the microhardness increased slightly,even the microhardness of the internal decreased.

关键词： laser-clad plasma-sprayed magnesium alloy Al-Si/Al+Al2O3 coating

Relation Entropy and Transferable Entropy Think of Aggregation on Group Decision Making

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Systems Science and Systems Engineering 2002年第1期11卷 13-18页

作者： CHENG Qi-yue, QIU Wan-hua, LIU Xiao-feng school of Management, Beijing univ.rsity of aeronautics and astronautics, Beijing 100083, china school of Management Beijing University of Aeronautics and Astronautics Beijing 100083 China

In this paper, aggregation question based on group decision making and a single decision making is studied. The theory of entropy is applied to the sets pair analysis. The system of relation entropy and the transferable entropy notion are put. The character is studied. An potential by the relation entropy and transferable entropy are defined. It is the consistency measure on the group between a single decision making. We gained a new aggregation effective definition on the group misjudge.

关键词： group decision making relation entropy transferable entropy

TWO－LEVEL MULTI－POINT APPROXIMATION METHOD FOR OPTIMUM DESIGN OF COMPLICATED STRUCTURES

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Chinese Journal of aeronautics 1995年第1期8卷 9-16页

作者： Huang Hai Xia Renwei(school of Space Science and technology, Beijing univ.rsity ofaeronautics and astronautics, Beijing, china, 100083)

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ＴＷＯ－ＬＥＶＥＬＭＵＬＴＩ－ＰＯＩＮＴＡＰＰＲＯＸＩＭＡＴＩＯＮＭＥＴＨＯＤＦＯＲＯＰＴＩＭＵＭＤＥＳＩＧＮＯＦＣＯＭＰＬＩＣＡＴＥＤＳＴＲＵＣＴＵＲＥＳＨｕａｎｇＨａｉ；ＸｉａＲｅｎｗｅｉ（ＳｃｈｏｏｌｏｆＳｐａｃｅＳｃｉｅｎｃｅａｎｄＴｅｃｈｎ...

关键词： structural design optimization approximation

A dual-kernel-based tracking approach for visual target

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Science china(Information Sciences) 2012年第3期55卷 566-576页

作者： ZHANG CanLong1,2 , JING ZhongLiang1, JIN Bo1 & LI ZhiXin2 1school of aeronautics & astronautics, Shanghai Jiao Tong univ.rsity, Shanghai 200240, china 2College of Computer Science & Information technology , Guangxi Normal univ.rsity, Guilin 541004, china 1. school of aeronautics & astronautics Shanghai Jiao Tong University Shanghai 200240 China2. College of Computer Science & Information Technology Guangxi Normal University Guilin 541004 China

A dual-kernel-based tracking approach for visual target is proposed in this paper. The similarity between candidate and target model, and the contrast between candidate and its neighboring background are considered simultaneously when evaluating a target candidate. The similarity is measured by Bhattacharyya coefficient while the contrast is calculated with Jensen-Shannon divergence, and they are adaptively fused into a novel objective function. By maximizing the linear approximation of objective function, a dual-kernel target location-shift relation from current location to a new location is induced. According to the location-shift relation, the optimal target location can be recursively gained in the mean shift procedure. Experimental evaluations on several image sequences demonstrate that the proposed algorithm can gain more accurate target location and better identification power to false target, and it is also robust to deformation and partial occlusion.

关键词： dual-kernel-based tracking mean shift Jensen-Shannon divergence Bhattacharyya coefficient

Ex vitro experimental study on concentration polari-zation of macromolecules (LDL) at an arterial stenosis

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Science china(Life Sciences) 2007年第4期50卷 486-491页

作者： ZHANG ZhiGuo1, DENG XiaoYan1,2, FAN YuBo2 & LI DeYu 2 1 State Key Laboratory of Structural Analysis for Industrial Equipment, dalian univ.rsity of technology, dalian 116023, china 2 Beijing univ.rsity of aeronautics and astronautics, Beijing 100083, china 1. State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116023 China 2. Beijing univ.rsity of aeronautics and astronautics Beijing 100083 China

To verify the previous theoretical prediction that the disturbed flow distal to a stenosis enhances lipid accumulation at the blood/arterial wall interface, we designed a canine carotid arterial stenosis model and measured ex vitro the luminal surface concentration of bovine serum albumin (as a tracer mac-romolecule) by directly taking liquid samples from the luminal surface of the artery. The experimental results showed that due to the presence of a filtration flow, the luminal surface albumin concentration cw was higher than the bulk concentration co as predicted by our theory. The measurement revealed that the luminal surface concentration of macromolecules was indeed enhanced significantly in re-gions of the disturbed flow. At Re = 50, the relative luminal surface concentration cw/co was 1.66 ± 0.10 in the vortex region, while the cw/co was 1.37 ± 0.06 in the laminar flow region. When Re increased to 100, the cw/co in the vortex flow region and the laminar flow region reduced to 1.39 ± 0.07 and 1.24 ± 0.04, respectively. The effect of the filtration rate, vw, on the luminal surface concentration of albumin was remarkably apparent. At Re = 50 and 100, when vw = 8.9 ± 1.7 × 10-6 cm/s, cw in the vortex region was 77% and 52% higher than co respectively, meanwhile when vw = 4.8 ± 0.6 × 10-6 cm/s, cw in the vortex region was only 66 % and 39% higher than co respectively. In summary, the present study has provided further experimental evidence that concentration polarization can occur in the arterial system and fluid layer with highly concentrated lipids in the area of flow separation point may be responsible for the formation and development of atherosclerosis.

关键词： concentration polarization atherosclerosis arterial stenosis flow disturbance