检索结果-南通市图书馆

Physical analysis and numerical simulation for the dynamic behaviour of vehicles in pitching oscillations or rocking motions

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2007年第4期50卷 385-401页

作者： ZHANG HanXin1,2,3. ZHANG Zhao1,3. YUAN XianXu1,2, LIU Wei1, XIE YuFei1,2 & YE YouDa1,2 1 china Aerodynamics Research and Development center, Mianyang 621000, china 2 National Laboratory for Computational Fluid Dynamics, {3. university of Aeronautics and Astronautics, {3. 100083. china 3.School of Aerospace, tsinghua university, beijing 100084, china 1. china Aerodynamics Research and Development center Mianyan 621000 China 2. National Laboratory for Computational Fluid Dynamics Beijing University of Aeronautics and Astronautics Beijing 100083 China 3. School of Aerospace Tsinghua University Beijing 100084 China

Analytical methods of nonlinear dynamics and numerical simulations for the cou-pling equations of Navier-Stokes and flight mechanics are used to study the dynamic behaviour of pitching motions of reentry capsules with the variation of Mach number, and rocking motions of swept wings with the variation of angle of attack. Conditions under which the dynamic instability, Hopf bifurcation and saddle-node bifurcation occur are obtained. The node-saddle-node topological structure in the phase portrait, i.e. the state of bi-attractors (attracting basins) is described. The evolving process of dynamic behaviour and flow fields are given. The theories are compared with some numerical simulations conducted by the authors. Besides, some verifiable experi-mental results are cited. The agreement between them is very well.

关键词： physical analysis numerical simulation pitching oscillation rocking motion bifurcation

The numbers of periodic orbits hidden at fixed points of 2-dimensional holomorphic mappings

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2010年第3期53卷 863-886页

作者： ZHANG GuangYuan Department of Mathematical Sciences, tsinghua university, beijing 100084, china 1. Department of Mathematical Sciences Tsinghua University Beijing 100084 China

Let △n be the ball |x| < 1 in the complex vector space C n , let f :△n→ C n be a holomorphic mapping and let M be a positive integer. Assume that the origin 0 = (0, . . . , 0) is an isolated fixed point of both f a... 详细信息

Let △n be the ball |x| 2. For a 2 × 2 matrix A that is arbitrarily given, the goal of this paper is to give a necessary and sufficient condition for A, such that O M (f, 0)≥2 for all holomorphic mappings f :△2 → C 2 such that f(0) = 0, Df(0) = A and that the origin 0 is an isolated fixed point of f M .

关键词： complex dynamical systems periodic points fixed point indices

GHG emission reductions and costs to achieve Kyoto target

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2003年第4期15卷 541-547页

作者： CHEN Wen\|ying (Energy, Environment and Economy Research Institute, tsinghua university, beijing 100084, china.) Energy Environment and Economy Research Institute Tsinghua University 北京 100084

Emission projection and marginal abatement cost curves(MACs) are the central components of any assessment of future carbon market, such as CDM (clean development mechanism) potentials, carbon quota price etc. However, they are products of very complex, dynamic systems driven by forces like population growth, economic development, resource endowments, technology progress and so on. The modeling approaches for emission projection and MACs evaluation were summarized, and some major models and their results were compared. Accordingly, reduction and cost requirements to achieve the Kyoto target were estimated. It is concluded that Annex I Parties' total reduction requirements range from 503.13.4 MtC with USA participation and decrease significantly to 140—612 MtC after USA's withdrawal. Total costs vary from 21—77 BUSD with USA and from 5—3. BUSD without USA if only domestic reduction actions are taken. The costs would sharply reduce while considering the three flexible mechanisms defined in the Kyoto Protocol with domestic actions' share in the all mitigation strategies drops to only 0—16%.

关键词： Kyoto Protocol emission reduction abatement cost flexible mechanisms

Multiparty quantum secret sharing of classical and quantum messages

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第1期17卷 26-31页

作者： CHEN Pan, DENG Fuguo and LONG Guilu ( Key Laboratory for Quantum Information and Measurements, and Department of Physics, tsinghua university, beijing 100084, china Key Laboratory of Beam Technology and Material Modification, MOE, Institute of Low Energy Nuclear Physics, and Department of Material Science and Engineering, {3. Normal university, {3. 100875, china {3. Radiation center, {3. 100875, china Key Laboratory for Atomic and Molecular Nano-Sciences, tsinghua university, beijing 100084, china) [a]Key Laboratory for Quantum Information and Measurements and Department of Physics Tsinghua University Beijing China [b]Key Laboratory of Beam Technology and Material Modification MOE Institute of Low Energy Nuclear Physics and Department of Material Science and Engineering Beijing Normal University Beijing China [c]beijing Radiation center Beijing China [d]Key Laboratory for Atomic and Molecular Nano-Sciences Tsinghua University Beijing China

A scheme for multiparty quantum secret sharing of classical and quantum messages is proposed by using entanglement swapping. This scheme can distribute not only the classical information but also the quantum informati... 详细信息

关键词： quantum secret sharing classical message quantum message EPR pair.

Entropy product measure for multipartite pure states

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 606-615页

作者： CAO Wancang1,2, LIU Dan2, PAN Feng3.& LONG Guilu2,4 1. Department of Physics, Chifeng College, Chifeng 024001, china 2. Key Laboratory for Quantum Information and Measurements, Department of Physics, tsinghua university, beijing 100084, china 3. Department of Physics, Liaoning Normal university, Dalian 116029, china 4. Key Laboratory for Atomic and Molecular Nano-Sciences, tsinghua university, beijing 100084, china Correspondence should be addressed to Long Guilu Department of Physics Chifeng College Chifeng 024001 China Key Laboratory for Quantum Information Measurements Department of Physics Tsinghua University Beijing 100084 China Department of Physics Liaoning Normal University Dalian 116029 China Key Laboratory for Atomic Molecular Nano-Sciences Tsinghua University Beijing 100084 China

An entanglement measure for multipartite pure states is formulated using the product of the von Neumann entropy of the reduced density matrices of the constituents. Based on this new measure, all possible ways of the maximal entanglement of the triqubit pure states are studied in detail and all types of the maximal entanglement have been compared with the result of ‘the average entropy’. The new measure can be used to calculate the degree of entanglement, and an improvement is given in the area near the zero entropy.

关键词： multipartite pure state von Neumann entropy entanglement measure

Application and Comparison of Two SGS Models in Large Eddy Simulation of FreeTurbulent Jet Flow

在线全文

学校读者我要写书评

暂无评论

Communications in Nonlinear Science and Numerical Simulation 1999年第1期4卷 12-19页

作者： Hong YAN and Mingde SU (Department of Engineering Mechanics, tsinghua university, beijing 100084, china) Department of Engineering Mechanics Tsinghua University Beijing 100084 China

Large eddy simulations of spatially evolved turbulent round jets were presented. The two SGS models called the standard Smagorinsky’s eddy viscosity model and the non-eddy viscosity stimulated small scale(SSS) model developed by Shah & Ferziger were applied. The Reynolds number of the flow was taken as 10000 based on the orifice diameter and the axial velocity in the orifice. The comparison between these two models showed that the standard Smagorinsky’s viscosity model with Smagorinsky’s constant of 0.1 underestimated the turbulent intensity, while the SSS model showed a better agreement with the experiment. Also the SSS model was used to investigate the development of vortex. The convective boundary condition at the outflow boundary was adopted to ensure less effect of noise on the upstream.

关键词： stimulated small scale model smagorinsky’s eddy viscosity model Round jet, Large eddy simulation

Design of policy mechanism to promote cleaner production in china

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2001年第3期13卷 346-350页

作者： ZHANG Tian zhu(Department of Environmental Science and Engineering, tsinghua university, beijing 100084, china. Department of Environmental Science and Engineering Tsinghua University Beijing 100084 China. zhangtz@***

In order to promote cleaner production in china, a package of policy options was presented based on the identification of the barriers encountered in the CP demonstration project and the effectiveness and feasibility of policy options for the CP implementation were analyzed. Furthermore, the policy mechanism framework was given, which composes of compulsory, economic incentive, social pressure and supportive function. Finally, the implementation strategy of the policy mechanism, in which the emphasis will be changed from compulsory policy options towards economic and social pressure policy options, was proposed.

关键词： cleaner production barrier identification policy mechanism china

ENTROPY,INFORMATION,NOISE-STUDIES ON SYSTEM EVOLUTION

在线全文

学校读者我要写书评

暂无评论

Systems Science and Systems Engineering 2003年第1期12卷 2-12页

作者： Weimin ZHENGSchool of Economics and Management tsinghua university. beijing 100084, china School of Economics and Management Tsinghua University

Universe, ecosystem, social system, etc. are evolving systems. The evolving processes of these systems have gradual small changes and rapid drastic changes with uncertainties under the constraints of environment. Systems, as a whole, are evolving toward complexity, diversity and variety with fluctuations and jumps. New order emerges from 'mutations'. The evolution is both chance-dependent and path-dependent. In this paper three basics: entropy, information and noise are emphasized with regard to system evolution which is a field that can give people wisdom to solve system problems with domain knowledge.

关键词： Entropy information noise

Electronic properties of multi-defected zigzag carbon nanotubes

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第1期53卷 11-15页

作者： QIAN HaiYun& ZHOU TaoDepartment of Physics, tsinghua university, beijing 100084, china 1. Department of Physics Tsinghua University Beijing 100084 China

Electronic properties of multi-defected zigzag single-walled carbon nanotubes are investigated by use of the tight-binding Green's function method. The Stone-Wales defects and the vacancies are considered. We find that the conductance sensitively depends on the realistic defect configurations for the metallic zigzag carbon nanotubes. Interestingly, the electronic transport properties of the nanotubes with three vacancies can be considered as the sum effect of two double-vacancies, while those with Stone-Wales defects can not. The electron interference along the longitudinal axis and the transport blocking are observed, which may be useful for understanding the electron transport behavior of carbon nanotube in experiments.

关键词： electronic transport multi-defected carbon nanotube defect configuration electron interference transport blocking