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A three-dimensional variational ocean data assimilation system:Scheme and preliminary results

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Science china Earth Sciences 2006年第11期49卷 1212-1222页

作者： ZHU Jiang1,2, ZHOU Guangqing1, YAN Changxiang1, FU Weiwei1 & YOU Xiaobao1,3.1. International Center for Climate and Environment Sciences, institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 10002., china 2. Jiangsu Key Laboratory of Meteorological Disaster, Nanjing University of Information Science and Technology, Nanjing 210044, china 3. beijing institute of applied meteorology, beijing 10002., china International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Jiangsu Key Laboratory of Meteorological Disaster Nanjing University of Information Science and Technology Nanjing China beijing institute of applied {3. Beijing China

A new 3.VAR-based Ocean Variational Analysis System (OVALS) is developed. OVALS is capable of assimilating in situ sea water temperature and salinity observations and satellite altimetry data. As a component of OVALS, a new variational scheme is proposed to assimilate the sea surface height data. This scheme considers both the vertical correlation of background errors and the nonlinear temperature-salinity relationship which is derived from the generalization of the linear balance constraints to the nonlinear in the 3.VAR. By this scheme, the model temperature and salinity fields are directly adjusted from the altimetry data. Additionally, OVALS can assimilate the temperature and salinity profiles from the ARGO floats which have been implemented in recent years and some temperature and salinity data such as from expendable bathythermograph, moored ocean buoys, etc. A 21-year assimilation experiment is carried out by using OVALS and the Tropical Pacific circulation model. The results show that the assimilation system may effectively improve the estimations of temperature and salinity by assimilating all kinds of observations. Moreover, the root mean square errors of temperature and salinity in the upper depth less than 420 m reach 0.63. and 0.3. psu.

关键词： data assimilation, 3.VAR, sea surface height, ARGO floats.

On the periodic solutions of a type of differential-iterative equations

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Chinese Science Bulletin 1998年第3期43卷 204-206页

作者： GE Weigao 1, LIU Zhengrong 2 and YU Yuanhong 3.1. Department of applied Mathematics, beijing institute of Technology, beijing 100081, china 2. Department of Mathematics, Yunnan University, Kunming 650091, china 3. institute of applied Mathematics, C Department of applied Mathematics Beijing Institute of Technology Beijing China Department of Mathematics Yunnan University Kunming China institute of applied Mathematics Chinese Academy of Sciences Beijing China

Sufficient conditions for the existence of periodic solutions to a type of nonautonomous differential_iterative equations are given.

关键词： differential_iterative equation periodic solution fixed point.

A new DNA algorithm to solve graph coloring problem

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Progress in Natural Science:Materials International 2007年第6期17卷 733-738页

作者： Jiang Xingpeng1, Li Yin2, Meng Ya3.and Meng Dazhi2(1. National Laboratory of Pattern Recognition,institute of Automation, Chinese Academy of Sciences, beijing 100080, china 2. College of {3. Sciences, beijing University of Technology, beijing 10002., china 3. School of Science, beijing institute of Technology, beijing 100081, china) National Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences Beijing 100080 China National High Magnetic Field Laboratory Florida State University 1800 East Paul Dirac Drive Tallahassee Florida 32306 USA

Using a small quantity of DNA molecules and little experimental time to solve complex problems successfully is a goal of DNA computing. Some NP-hard problems have been solved by DNA computing with lower time complexity than conventional computing. However, this advantage often brings higher space complexity and needs a large number of DNA encoding molecules. One example is graph coloring problem. Current DNA algorithms need exponentially increasing DNA encoding strands with the growing of problem size. Here we propose a new DNA algorithm of graph coloring problem based on the proof of four-color theorem. This algorithm has good properties of needing a relatively small number of operations in polynomial time and needing a small number of DNA encoding molecules (we need only 6R DNA encoding molecules if the number of regions in a graph is R).

关键词： DNA computing NP-hard problem graph coloring problem.

New progress in the principle of nonequilibrium statistical physics

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Chinese Science Bulletin 2001年第6期46卷 448-454页

作者： XING XiusanDepartment of applied Physics, beijing institute of Technology, beijing 100081, china Department of applied Physics Beijing Institute of Technology Beijing China

In recent years, a new fundamental equation of nonequilibrium statistical physics was proposed in place of the Liouville equation. That is the anomalous Langevin equation in (?) space or its equivalent Liouville diffusion equation of time-reversal asymmetry. This equation reflects that the form of motion of particles in statistical thermody-namic systems has the drift-diffusion duality and the law of motion of statistical thermodynamics is stochastic in essence, but does not obey the Newton equation of motion, though it is also constrained by dynamics. The stochastic diffusion of the particles is the microscopic origin of macroscopic irre-versibility. Starting from this equation, the BBGKY diffusion equation hierarchy was presented, the hydrodynamic equations, such as the generalized Navier-Stokes equation, the mass drift-diffusion equation and the thermal conductivity equation have been derived succinctly. The unified description of all three level equations of microscopic, kinetic and hydrodynamic

关键词： anomalous Langevin equation in space drift-diffusion duality stochastic law nonequilibrium entropy evolution equation entropy diffusion.

Using directional data method for analysis on typhoon movement and its probability distribution features

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Acta Oceanologica Sinica 1988年第4期7卷 496-501页

作者： Shi Jiuen, Chen Xiaoming and Xiang Jingtian beijing institute of meteorology, beijing, chinainstitute of applied Mathematics, Acadcmia Sinica, beijing, china beijing institute of meteorology Beijing China China

In many scientific fields such as meteorology, biology, geography, oceanography and astronomy, the angle value is very important, for example, wind directions, and the directions on which animals and birds migrate. This kind of data is called as directional data. In some problems, it is not expressed as 'angle' value, such as month by month mean temperature, however, it can be changed into a directional data through some transformations. The statistical method of directional data means that the methods of mathematical statistics are used in the treatment of directional data. In this way, data are considered as the points on two-dimensional cycle or higher dimensional sphere. Therefore, this method can also be called statistics on sphere. Because of its own characteristical feature, the statistics of directional data much differ from common statistics. Up to now, research work in this field has just started in china. In this paper, a statistical study on typhoon moving directions after their formation ov

关键词： Using directional data method for analysis on typhoon movement and its probability distribution features data

ON THE EXISTENCE OF SOLUTIONS TO A TYPE OF NONLINEAR DIFFERENTIAL-ITERATIVE EQUATIONS

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Chinese Annals of Mathematics,Series B 2000年第2期21卷 217-224页

作者： GE WEIGAO(Department of applied Mathematics, beijing institute of Technology, beijing 100081, china.) LI CUIZHE(Department of applied Mathematics, beijing institute of Technology, beijing 100081, china.) YU YUANHONG(Inditute of applied Mathematics, Acad Department of applied Mathematics Beijing Institute of Technology Beijing 100081 China institute of applied Mathematics Academia Sinica Beijing 100080 China

Under the assumption that h(z) is strictly monotone the existence of solutions to a type of nonlinear differential-iterative equations in the form of x’(t) = g(x(t)) -h(x(x(t))) is discussed according to the behavior... 详细信息

关键词： Differential-iterative equation Quasi-isoclinic curve Fixed point

Lie symmetry and conservation law of Birkhoffian system

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Chinese Science Bulletin 1999年第4期44卷 318-320页

作者： MEI FengxiangDepartment of applied Mechanics , beijing institute of Technology, beijing 100081, china Department of applied Mechanics Beijing Institute of Technology Beijing China

The Lie symmetry of Birkhoffian system was studied, the condition under which the system admits the one-parameter Lie group of transformation with infinitesimal generator was given, and the structural equation and the... 详细信息

关键词： symmetry conservation law Birknoffian system.

Non-Noether conserved quantity for differential equations of motion in the phase space

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Chinese Science Bulletin 2002年第24期47卷 2049-2050页

作者： MEI FengxiangDepartment of applied Mechanics, beijing institute of Technology, beijing 100081, china Department of applied Mechanics Beijing Institute of Technology Beijing China

A non-Noether conserved quantity for the differential equations of motion of mechanical systems in the phase space is studied. The differential equations of motion of the systems are established and the determining equations of Lie symmetry are given. An existence theorem of non-Noether conserved quantity is obtained. An example is given to illustrate the application of the result.

关键词： mechanical system phase space non-Noether conserved quantity.

Accuracy of Lax-Wendroff scheme for discontinuous solutions of convection equations

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Chinese Science Bulletin 1997年第24期42卷 2047-2051页

作者： DING LijuanDepartment of applied Mathematics, beijing institute of Technology, beijing 100081, china Department of applied Mathematics Beijing Institute of Technology Beijing China

IT is known from Brenner, Thomee and Wahlbin that the well-known second-order Lax-Wendroff scheme is stable in L^2, but unstable in L^p, p≠2. Generally speaking, if the initialdata is smooth enough and if a difference scheme, which is stable in L^p for some p, has orderof accuracy μ, then we can expect that the solution of the difference scheme converges to thesolution of the differential equation at the rate of order μ in L^p. But for discontinuous solu-tions, which are essential to hyperbolic equations, the above expectation is not true. Error es-timates for discontinuous solutions not only have theoretical meaning, but also practical value.

关键词： Lax-Wendroff scheme modlfled equation discontinuous solutions error estimate.