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ON COMPLEX DYNAMIC CONTROL systems

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Journal of systems science & Complexity 2003年第3期16卷 350-357页

作者： CHENG Daizhan (institute of systems science, chinese academy of sciences, beijing 100080, china) institute of systems science Chinese Academy of Sciences 北京 100080

This paper presents some recent works on the control of dynamic systems,which have certain complex properties caused by singularity of the nonlinear structures,structure^varyings, or evolution process etc. First, we consider the structure singularity of nonlinear control systems. It was revealed that the focus of researches on nonlinear control theory is shifting from regular systems to singular systems. The singularity of nonlinear systems causes certain complexity. Secondly, the switched systems are considered. For such systems the complexity is caused by the structure varying. We show that the switched systems have significant characteristics of complex systems. Finally, we investigate the evolution systems. The evolution structure makes complexity, and itself is a proper model for complex systems.

关键词： relative degree byrnes-isidori normal form center manifold switchedsystems evolution system

δ-WAVE FOR 1-D AND 2-D HYPERBOLIC systems

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Journal of Computational Mathematics 1996年第3期14卷 256-262页

作者： S.L. Yang(institute of Applied Mathematics, chinese academy of sciences, beijing, china) 中科院应用数学所北京

Here a new kind of nonlinear wave, which is called δ-wave, is described by some high resolution difference solutions for Riemann problems of one-dimensional (1-D) and two-dimensional (2-D) nonlinear hyperbolic systems in conservation laws. Some phenomena are numerically shown for the solutions of Riemann problems for 2-D gas dynamics systems

关键词： Zhang WAVE FOR 1-D AND 2-D HYPERBOLIC systems

Astronomical function and date of the Taosi observatory

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science china(Physics,Mechanics & Astronomy) 2009年第1期52卷 151-158页

作者： WU JiaBi1, CHEN MeiDong2 & LIU CiYuan3 1 National Astronomical Observatories, chinese academy of sciences, beijing 100012, china 2 institute for the History of Natural science, chinese academy of sciences, beijing 100010, china 3 National Time Service Center, chinese academy of sciences, Xi’an 710600, china National Astronomical Observatories Chinese Academy of Sciences Beijing China institute for the History of Natural science Chinese Academy of Sciences Beijing China National Time Service Center Chinese Academy of Sciences Xi’an China

The Taosi site in Xiangfen County,Shanxi Province,may be the capital of the King Yao. Archeologists recently discovered a large semi-circular stamped-earth platform, II FJT1,which has a clear and definite pounded-earth central core together with a curved wall perforated by twelve gaps. The platform is said to be an ancient observatory used to determine the seasons by watching the sunrise. Each feature of II FJT1 was precisely measured and the data are reproduced in this paper. An astronomical analysis of slots E2 and E12 was carried out using the azimuths of the slots' centerlines and the vertical angle of the mountain ridge opposite, above which the sun rises. The results show that at present the sun is close to the two slots but does not exactly enter them at summer and winter solstice sunrise. Using 14C analysis archeologists dated the site to about 2100 BC. Because of the secular change in the obliquity of the ecliptic,at that date on the summer solstice the half-risen sun would have appeared inside slot E12 just to the right of the centerline,and on the winter solstice the sun would have been exactly on the centerline of slot E2. This result provides compelling proof that II FJT1 is an ancient observatory.

关键词： astro-archeology astro-chronology Taosi culture ancient observatory time service

BOUNDARY STABILIZATION OF TIMOSHENKO BEAM

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systems science and Mathematical sciences 2000年第4期13卷 376-384页

作者： YAN Qingxu (institute of systems science, chinese academy of sciences, beijing 100080, china) 中科院系统科学所北京 100080

In this paper, the stabilization problem of Timoshenko beam by some nonlinear boundary feedback controls is considered. By virtue of nonlinear semigroup theory and energy-perturbed method, it is shown that the vibrati... 详细信息

关键词： Timoshenko beam boundary feedback stabilization nonlinear semigroups energy perturbed method.

Challenges and innovations in green process intensification

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science china Chemistry 2010年第7期53卷 1470-1475页

作者： LIU HuiZhou,LIANG XiangFeng,YANG LiangRong & CHEN JiaYong institute of Process Engineering,chinese academy of sciences,beijing 100190,china institute of Process Engineering Chinese Academy of Sciences Beijing China

Process intensification is one of the most significant trends in current chemical engineering and process *** recent years,the desire to become more "green" in processing has always been tied to the requirement of being *** review discusses the challenges of process engineering and summarizes the key role of fundamentals for green process intensification.

关键词： green chemistry process intensification

Progress in modeling of fluid flows in crystal growth processes

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Progress in Natural science:Materials International 2008年第12期18卷 1465-1473页

作者： Qisheng Chen Yanni Jiang Junyi Yan Ming Qin institute of Mechanics.chinese academy of sciences,beijing 100190,china institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

Modeling of fluid flows in crystal growth processes has become an important research area in theoretical and applied *** crystal growth processes involve fluid flows,such as flows in the melt,solution or *** modeling has played an important role in developing technologies used for growing semiconductor crystals for high performance electronic and optoelectronic *** application of devices requires large diameter crystals with a high degree of crystallographic perfection,low defect density and uniform dopant *** this article,the flow models developed in modeling of the crystal growth processes such as Czochralski,ammono- thermal and physical vapor transport methods are *** the Czochralski growth modeling,the flow models for thermocapillary flow,turbulent flow and MHD flow have been *** the ammonothermal growth modeling,the buoyancy and porous media flow models have been developed based on a single-domain and continuum approach for the composite fluid-porous layer *** the physical vapor transport growth modeling,the Stefan flow model has been proposed based on the flow-kinetics theory for the vapor *** addition,perspectives for future studies on crystal growth modeling are proposed.

关键词： Modeling Crystal growth Fluid flow Czochralski growth Ammonothermal growth Physical vapor transport

Transformations and non-degenerate maps

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science china Mathematics 2005年第Z1期48卷 195-205页

作者： LI Baokui & WANG Yuefei institute of Mathematics, academy of Mathematics and System sciences, chinese academy of sciences, beijing 100080, china Graduate School, chinese academy of sciences, beijing 100080, china institute of Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China Graduate School Chinese Academy of Sciences Beijing China

We shall prove the equivalences of a non-degenerate circle-preserving map and a M(o)bius transformation in ^Rn, of a non-degenerate geodesic-preserving map and an isometry in Hn of a non-degenerate line-preserving map and an affine transformation in Rn. That a map is non-degenerate means that the image of the whole space under the map is not a circle, or geodesic or line respectively. These results hold without either injective or surjective, or even continuous assumptions, which are new and of a fundamental nature in geometry.

关键词： M(o)bius transformation, circle-preserving map, non-degenerate map.

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

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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

Unsteady Numerical Simulation of Hot Streak/Blades Interaction and Film Cooling

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Journal of Thermal science 2010年第5期19卷 402-409页

作者： Weilin Yi,Lucheng Ji and Yunhan Xiao Research Center for Energy and Power,chinese academy of sciences,beijing,china Key Laboratory of Advanced Energy and Power,chinese academy of sciences,(institute of Engineering Thermophysics),beijing,china P.O.Box 2706,beijing 100190,china Research Center for Energy and Power Chinese Academy of Sciences Beijing China Key Laboratory of Advanced Energy and Power Chinese Academy of Sciences (Institute of Engineering Thermophysics) Beijing China beijing China

Deeply research on management and application of hot streak is an important way to breakthrough technique obstacle of aero engine hot *** method is a useful instrument to investigate the correlative *** the paper developed independently three dimensional unsteady parallel computational code-MpiTurbo based on Fortran 90 and MPI at Linux operating *** unsteady numerical simulation was carried out to investigate impacts of the factors,which included circumferential locations of hot streak and clocking positions of blade rows,on the thermal environment of a 1+1 counter-rotating *** results clearly indicated that clocking positions of hot streak/blade row and blade row/blade row had great influence on the time-averaged temperature distribution of the third blade ***,it can be effective for improving thermal environment of turbine to optimize blade parameters and clocking *** film cooling layout was designed by the repetitious steady simulation based on source term *** the flow structure detail was given by the unsteady simulation.

关键词： hot streak turbine parallel computation film cooling