检索结果-南通市图书馆

Integrated precise orbit determination of Shenzhou IV unmanned spacecraft

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2004年第5期47卷 518-525页

作者： L Congmin1,2, GU Yidong3, LIN Baojun3 & GUO Jiong3 1. Center for Space science and Applied Research, chinese academy of sciences, beijing 100080, china 2. Graduate School of the chinese academy of sciences, beijing 100039, china 3. General Establishment of Space science and Application, chinese academy of sciences, beijing 100080, china Correspondence should be addressed to L Congmin Center for Space science and Applied Research Chinese Academy of Sciences Beijing China Graduate School of the chinese academy of sciences Beijing China General Establishment of Space science and Application Chinese Academy of Sciences Beijing China

Considering the characteristic orbit of Shenzhou IV spacecraft and the advantages and disadvantages of several types of domestic orbit measurements, a scheme of IPOD is determined, which uses GPS, SLR and USB observation data jointly plus precise ionosphere corrections to GPS observation data. IPOD system and mathematic models of OD are introduced. The results of different joint OD are analyzed using true observation data, and show that radial accuracy is better than 2 m.

关键词： Shenzhou IV unmanned spacecraft integrated precise orbit determination GPS SLR USB.

Flow Instability and Its Control in Compression systems

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal science 2003年第1期12卷 1-9页

作者： Jingyi ChenInstitute of Engineering Thermophysics, chinese academy of sciences, beijing 100080, china Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing China

This paper reviews the development in the research of flow instability and its control over the recent ten or more years. This development was largely stimulated by the novel idea of active control of the aerodynamic instability in compressors. Three topics are covered in the paper, which appeared as the major themes towards the goal of stability enhancement. The first topic is the pre-stall behavior of rotating stall, which plays a vital role in designing the control scheme and discovering the convenient route to find the causal factors of flow disturbances potentially leading to stall. The second topic is the mechanism of blade passage flow during stall and its inception, which is the basic knowledge needed to manipulate the blade design for the stability improvement and eventually to predict the unsteady performance of the compressor system. The third topic is the recent trend of the control strategy based on the learning of active vs. passive methods. To introduce to the discussion of these topics, a brief description of the history of the recent development is given at the beginning of the paper. In discussing each topic, future works are also highlighted to enhance the further development of this long-standing problem in turbomachinery research and application.

关键词： compressors rotating stall pre-stall active/passive control wavelet.

Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & Technology 2000年第1期16卷 50-54页

作者： Lingchuan LI (Institute of Chemical Metallurgy, chinese academy of sciences, beijing 100080, china) Institute of Chemical Metallurgy Chinese Academy of Sciences Beijing 100080 China

Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a film of Ni oxide precursor was developed on the surface of the porous oxide film. The Ni particles and the Ni oxide precursor were examined by SEM, TEM and X-ray diffraction. The thickness of the barrier layer of the porous oxide film was thin and it attributed to the formation of the metal particles, while the formation of the oxide precursor was associated with the surface pits which were developed in the pretreatment of Al.

关键词： Al Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

Bifurcation and Chaos in a Weakly Nonlinear system Subjected to Combined Parametric and External Excitation

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2002年第3期18卷 501-512页

作者： Wei Li, Peng-cheng XuInstitute of mathematics, beijing University of Chemical Technology, beijing 100029, chinaInstitute of Applied mathematics, academy of mathematics and system sciences, chinese academy of sciences, beijing 100080, china Institute of mathematics Beijing University of Chemical Technology Beijing China Institute of Applied mathematics Academy of Mathematics and System Sciences Chinese Academy of Science Beijing China

In this paper the dynamics of a weakly nonlinear system subjected to combined parametric and external excitation are discussed. The existence of transversal homoclinic orbits resulting in chaotic dynamics and bifurcation are established by using the averaging method and Melnikov method. Numerical simulations are also provided to demonstrate the theoretical analysis.

关键词： Bifurcation chaos transversal homoclinic orbit

Multisymplectic Structure and Multisymplectic Scheme for the Nonlinear Ware Equation

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2002年第1期18卷 169-176页

作者： Yu-shun WANG, Meng-zhao QINLASG, Institute of Atmospheric Physics, chinese academy of sciences, beijing 100029, chinaInstitute of Computational mathematics, academy of mathematics and system sciences, chinese academy of sciences, beijing 100080, china LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Institute of Computational mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China

The multisymplectic structure of the nonlinear wave equation is derived directly from the variational principle. In the numerical aspect, we present a multisymplectic nine points scheme which is equivalent to the multisymplectic Preissman scheme. A series of numerical results are reported to illustrate the effectiveness of the scheme.

关键词： Multisymplectic structure Multisymplectic schemes Nonlinear wave equation

A new approach of cascade utilization of the chemical energy of fuel

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2006年第5期16卷 518-523页

作者： HAN Wei, JIN Hongguang and LIN Rumou ( Institute of Engineering Thermophysics, chinese academy of sciences, beijing 100080, china Graduate School of the chinese academy of sciences, beijing 100080, china) Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100080 China Graduate School of the chinese academy of sciences Beijing 100080 China

The indirect release of chemical energy of fuel is investigated, and a new mechanism is proposed to identify the cascade utilization of chemical energy of fuel more clearly. Based on the concept of energy level, the internal phenomenon of the indirect chemical energy release is disclosed, and the equations of energy level describing the utilization of chemical energy and thermal energy during the indirect chemical energy release process are obtained. From theoretical analysis, we find that the superiority of the indirect chemical energy release of fuel comes from the cascade utilization of the fuel's chemical energy. Moreover, the cascade utilization of chemical energy is verified by the investigation of CRGT (chemically recuperated gas turbine). As a result, the thermal exergy obtained from the chemical energy release of fuel increases by 2 % -3 % . The results obtained here may help a deeper understanding of indirect chemical energy release of fuel and provide a theoretical basis for the synthesis of innovative energy systems.

关键词： chemically recuperated gas turbine methane/steam reforming chemical energy level cascade utilization.

Applications of the theory of Grbner bases to the study of linear recurring arrays

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

chinese science Bulletin 2001年第14期46卷 1149-1152页

作者： LIU MulanThe academy of mathematics of systems sciences, chinese academy of sciences, beijing 100080, china The academy of mathematics of systems sciences Chinese Academy of Sciences Beijing China

This is a small survey of applications of the theory of Grobner bases to the study of linear recurring arrays. It applies some properties of Grobner bases to studying linear recurring arrays and contains recent new re... 详细信息

关键词： Grobner bases linear recurring arrays module structure localization.

An Adaptive Neural Network Model for Nonlinear Programming Problems

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2002年第3期18卷 377-388页

作者： Xiang-sun Zhang, Xin-jian Zhuo, Zhu-jun Jingacademy of mathematics and system sciences, chinese academy of sciences, beijing 100080, chinaSchool of Information Engineering, beijing University of Posts and Telecommunications, beijing 100876, chinaHunan Normal University, Changsha 410081, china & academy of mathematics and system sciences, chinese academy of sciences, beijing 100080, china academy of mathematics and system sciences Chinese Academy of Sciences Beijing China School of Information Engineering Beijing University of Posts and Telecommunications Beijing China Hunan Normal University Changsha China

In this paper a canonical neural network with adaptively changing synaptic weights and activation function parameters is presented to solve general nonlinear programming problems. The basic part of the model is a sub-network used to find a solution of quadratic programming problems with simple upper and lower bounds. By sequentially activating the sub-network under the control of an external computer or a special analog or digital processor that adjusts the weights and parameters, one then solves general nonlinear programming problems. Convergence proof and numerical results are given.

关键词： Adaptive neural network canonical neural network general nonlinear programming

The Multifractal Analysis of the Occupation Measure of a Lévy Process

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural sciences 2000年第3期5卷 253-256页

作者： Hu Xiao\|yu Institute of Applied mathematics, chinese academy of sciences, beijing 100080, china Institute of Applied mathematics Chinese Academy of Sciences Beijing 100080 China

We introduce the results on the multifractal structure of the occupation measures of a Brownian Motion, a stable process, a general subordinator and a stochastic process derived from random reordering of the Cantor se... 详细信息

关键词： occupation measure Levy process Brownian motion stable process subordinator