检索结果-南通市图书馆

CONVERGENCE OF VORTEX METHODS FOR 3-D EULER EQUATIONS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational mathematics 2000年第3期18卷 239-250页

作者： Jia-fu Lin (institute of system science, academy of mathematics and system sciences, chinese academy of sciences, beijing, 100080, china school of Mathematical sciences, Peking University, beijing 100871, china) 中科院系统科学所北京 100080

Presents a study on the convergence of vortex methods for the three-dimensional Euler equations in bounded domains. Related studies on the convergence of vortex methods; Formulation of vortex methods; Convergence for ... 详细信息

关键词： Euler equations vortex methods convergence initial-boundary value problem

ON THE CENTRAL RELAXING SCHEME Ⅱ: systems OF HYPERBOLIC CONSERVATION LAWS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational mathematics 2001年第6期19卷 571-582页

作者： Hua-zhong Tang (school of Mathematical sciences, Peking University, beijing 100871, china) (LSEC,ICMSEC academy of mathematics and systems sciences, chinese academy of sciences, beijing 100080, china) school of Mathematical sciences Peking University Beijing 100871 China

This paper continues to study the central relaxing schemes for system of hyperbolic conservation laws, based on the local relaxation approximation. Two classes of relaxing systems with stiff source term are introduced to approximate system of conservation laws in curvilinear coordinates. Based on them, the semi-implicit relaxing schemes are con- structed as in [6, 12] without using any linear or nonlinear Riemann solvers. Numerical experiments for one-dimensional and two-dimensional problems are presented to demon- strate the performance and resolution of the current schemes.

关键词： Hyperbolic conservation laws The relaxing system The central relaxing schemes The Euler equations.

On the local wellposedness of 3-D water wave problem with vorticity

在线全文

学校读者我要写书评

暂无评论

science china mathematics 2007年第8期50卷 1065-1077页

作者： Ping ZHANG~1 Zhi-fei ZHANG~2 1 academy of mathematics and systems science,chinese academy of sciences,beijing 100080,china 2 school of Mathematical sciences,Peking University,beijing 100871,china academy of mathematics systems science Chinese Academy of Sciences Beijing 100080 China school of Mathematical sciences Peking University Beijing 100871 China

In this article, we first present an equivalent formulation of the free boundary problem to 3-D incompressible Euler equations, then we announce our local wellposedness result concerning the free boundary problem in Sobolev space provided that there is no self-intersection point on the initial surface and under the stability assumption that $\frac{{\partial p}}{{\partial n}}(\xi )\left| {_{t = 0} } \right. \leqslant - 2c_0 < 0$ being restricted to the initial surface.

关键词： water-waves free boundary incompressible Euler equations primary 35Q35 76B03 secondary 35J67 35L80

A note on noncommutative moment problems

在线全文

学校读者我要写书评

暂无评论

science china mathematics 2005年第8期48卷 1144-1151页

作者： MA Xiujuan school of sciences, Hebei University of Technology, Tianjin 300130, china mathematics institute, academy of mathematics and systems science, chinese academy of sciences, beijing 100080, china 1. school of sciences Hebei University of Technology 300130 Tianjin China 2. mathematics institute Academy of Mathematics and Systems Science Chinese Academy of Sciences 100080 Beijing China

Noncommutative moment problems for C*-algebras are studied. We generalize a result of Hadwin on tracial states to nontracial case. Our results are applied to obtain simple solutions to moment problems on the square and the circle as well as extend the positive unital functionals from a (discrete) complex group algebra to states on the group C*-algebra.

关键词： moment, free product, state, group C*-algebra.

Nonlinear autoregressive models with heavy-tailed innovation

在线全文

学校读者我要写书评

暂无评论

science china mathematics 2005年第3期48卷 333-340页

作者： JIN Yang & AN Hongzhi school of Statistics, Renmin University of china, beijing 100872, china academy of mathematics and systems science, chinese academy of sciences, beijing 100080, china Sch. of Statistics Renmin Univ. of China Beijing 100872 China Acad. of mathematics and Syst. Sci. Chinese Acad. of Sci. Beijing 100080 China

In this paper, we discuss the relationship between the stationary marginal tail probability and the innovation's tail probability of nonlinear autoregressive models. We show that under certain conditions that ensure the stationarity and ergodicity, one dimension stationary marginal distribution has the heavy-tailed probability property with the same index as that of the innovation's tail probability.

关键词： nonlinear autoregressive model, innovation, tail probability.

A novel operation mode for spaceborne polarimetric SAR

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第4期54卷 884-897页

作者： QI WeiKong 1,2 & YU WeiDong 1 1 institute of Electronics,chinese academy of sciences,beijing 100190,china 2 graduate school of chinese academy of sciences,beijing 100039,china 1. institute of Electronics Chinese Academy of Sciences Beijing 100190 China2. Graduate School of Chinese Academy of Sciences Beijing 100039 China

A novel operation mode for spaceborne polarimetric SAR,named polarization space-division adding polarization code-division (PSD-PCD) operation mode,is proposed in this paper through combining polarimetric SAR with elevation digital beam-forming (DBF) on *** a pulse repetition interval the up-chirp LFM sub-pulse is transmitted with horizontal polarization antenna,and with some delay the down-chip LFM subpulse is transmitted with vertical polarization antenna to realize code *** every sub-aperture receives returns from ground,SAR system uses range DBF to separate echoes relative to different sub-pulses in order to realize space *** system PRF is equal to that of single-polarization SAR,and elevation DBF help reduce range ambiguity ***,the main system parameters,including PRF,delay between two sub-pulses,radar equation and ambiguity are analyzed and compared with those of single-polarization *** results demonstrate the feasibility and validity of PSD-PCD operation mode.

关键词： spaceborne synthetic aperture radar (SAR) polarimetry digital beamforming (DBF) operation mode ambiguity ratio polarization space-division polarization code-division

BOUNDARY FEEDBACK STABILIZATION OF NONUNIFORM TIMOSHENKO BEAM WITH A TIPLOAD

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 Annals of mathematics,Series B 2001年第4期22卷 485-494页

作者： YAN QINGXU, FENG DEXING institute of systems science, academy of mathematics and systems science, chinese academy of sciences, beijing 100080, china. institute of systems science, academy of mathematics and systems science, chinese academy of sciences, Be institute of systems science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China

The boundary stabilization problem of a Timoshenko beam attached with a mass at one end is studied. First, with linear boundary force feedback and moment control simultaneously at the end attached with the load, the energy corresponding to the closed loop system is proven to be exponentially convergent to zero as time t →∞. Then, some counterexamples are given to show that, in other casest the corresponding closed loop system is, in general, not stable asymtotically, let alone exponentially.

关键词： Timoshenko beam Boundary feedback control C0 semigroups Exponential stability Multiplier method

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) [a]institute of Engineering Thermophysics Chinese Academy of Sciences Beijing China [b]graduate school of the chinese academy of sciences Beijing 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.

IMPLICITIZATION USING UNIVARIATE RESULTANTS

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 systems science & Complexity 2010年第4期23卷 804-814页

作者： Liyong SHEN Chunming YUAN school of Mathematical sciences Graduate University Chinese Academy of Sciences Beijing 100049 China Key Laboratory of mathematics Mechanization Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

Among several implicitization methods, the method based on resultant computation is a simple and direct one, but it often brings extraneous factors which are difficult to remove. This paper studies a class of rational space curves and rational surfaces by implicitization with univaxiate resultant computations. This method is more efficient than the other algorithms in finding implicit equations for this class of rational curves and surfaces.

关键词： Implicitization rational space curves rational surfaces resultants.