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Influence of magnetic current on the ground state entanglement in an isotropic transverse XY chain

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Progress in Natural Science:Materials International 2007年第10期17卷 1147-1151页

作者： Liu Dan1,2 , Zhang Yong3.and Long Guilu1,2(1. Key Laboratory for Atomic and Molecular NanoSciences, and department of Physics, Tsinghua University, beijing 100084, China 2. Center of Quantum Information Science and technology, Tsinghua National Laboratory for information Science and technology, beijing 100084, China 3. institute of Physics, School of Sciences, beijing University of Posts and Telecommunications, beijing 100876, China) Key Laboratory for Atomic and Molecular NanoSciences and Department of Physics Tsinghua University Beijing 100084 China Center of Quantum Information Science and technology Tsinghua National Laboratory for information Science and Technology Beijing 100084 China institute of Physics School of Sciences Beijing University of Posts and Telecommunications Beijing 100876 China

We study the ground state entanglement in a three-qubit XY chain under the influence of a magnetization current. It is found that the ground state changes from a W state to a disentangled state as the magnetic field varies. When the Lagrange multiplier λ>3. namely under a strong magnetic current, the ground state holds onto a W state for a large range of the magnetic field strength. A phase transition to the magnetization-current phase occurs under a certain condition.

关键词： Heisenberg-XY chain magnetic-current phase transition.

ON THE ESSENTIAL SPECTRUM OFPSEUDODIFFERENTIAL OPERATORS (II)

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Chinese Annals of mathematics,Series B 1994年第3期15卷 327-334页

作者： FAN QIRONG(institute & department of mathematics, beijing Unversity) beijing 100071, China.)

This paper continues the studies of the essential spectrum Of nonsemi-bounded pseudodifferential operators. The author improves the results in [5] in some sense. For the relativisticSchredinger operator, ￣ + v(x), co... 详细信息

关键词： Essential spectrum Pseudodifferelltial operator Schrsdiliger operator.

CONVERGENCE RATES TO TRAVELLING WAVES FOR A RELAXATION MODEL WITH LARGE INITIAL DISTURBANCE

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Acta Mathematica Scientia 2004年第2期24卷 213-227页

作者：张辉赵引川 departmentofmathematics BeijingNormalUniversityBeijing100825China

This paper is concerned with the convergence rates to travelling waves for a relaxation model with general flux functions. Compared with former results in this direction, the main novelty in this paper lies in the fact that the initial disturbance can be chosen large in suitable norm. Our analysis is based on the L^1-stability results obtained by C. Mascia and R. Natalini in [12].

关键词： Convergence rate relaxation travelling waves large initial disturbance

Parameter identification theory of a complex model based on global optimization method

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Science China(Physics,Mechanics & Astronomy) 2008年第11期51卷 1722-1732页

作者： QU Jie1, JIN QuanLin2 & XU BingYe3.1 College of Automotive Engineering, South China University of technology, Guangzhou 510640, China 2 beijing Research institute of Mechanical and Electrical technology, beijing 100083. China 3.department of Engineering Mechanics, Tsinghua University, beijing 100084, China 1. College of Automotive Engineering South China University of Technology Guangzhou 510640 China 2. beijing Research institute of Mechanical and Electrical technology Beijing 100083 China 3. department of Engineering Mechanics Tsinghua University Beijing 100084 China

With the development of computer technology and numerical simulation technology, computer aided engineering (CAE) technology has been widely applied to many fields. One of the main obstacles, which hinder the further application of CAE technology, is how to successfully identify the parameters of the selected model. An elementary framework for parameter identification of a complex model is provided in this paper. The framework includes the construction of objective function, the design of the optimization method and the evaluation of the identified results, etc. The parameter identification process is described in this framework, taking the parameter identification of the superplastic constitutive model considering grain growth for Ti-6Al-4V at 927°C as an example. The objective function is the weighted quadratic sums of the difference between the experimental and computational data for the stress-strain relationship and the grain growth relationship; the designed optimization method is a hybrid global optimization method, which is based on the feature of the objective function and incorporates the strengths of genetic algorithm (GA), the Levenberg-Marquardt algorithm and the augmented Gauss-Newton algorithm. The reliability evaluation of parameter identification result is made through the comparison between the calculated and experimental results and between the theoretical values of the parameters and the identified ones.

关键词： constitutive model parameter identification theory inverse analysis global optimization

Gerbes and twisted orbifold quantum cohomology

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Science China mathematics 2008年第6期51卷 995-1016页

作者： PAN JianZhong~1 RUAN YongBin~(2,3. YIN XiaoQin~(1,3.) 1 institute of mathematics,Academy of mathematics and Systems Science,Chinese Academy of Sciences,{3. 100080,China 2 department of mathematics,University of Wisconsin-Madison,WI 53.06,USA 3.department of mathematics,The Hong Kong University of Science and technology,Hong Kong,China institute of mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China department of mathematics University of Wisconsin-Madison WI 53706 Madison USA department of mathematics The Hong Kong University of Science and Technology Hong Kong China

In this paper,we construct an orbifold quantum cohomology twisted by a flat gerbe. Then we compute these invariants in the case of a smooth manifold and a discrete torsion on a global quotient orbifold.

关键词： gerbe orbifold quantum cohomology 53.45

Timeliness evaluation of task-oriented networked space-based information system

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Journal of Systems Engineering and Electronics 2011年第4期22卷 621-627页

作者： Chen Chen 1,2,and Jie Chen 2,3.1.department of Automation,Tsinghua University,beijing 100084,P.R.China 2.School of Automation,beijing {3. of technology,beijing 100081,P.R.China 3.Complex System Intelligent Control and Decision,Ministry of Education,beijing 100081,P.R.China department of Automation Tsinghua University Beijing 100084 P. R. China School of Automation Beijing Institute of Technology Beijing 100081 P. R. China School of Automation Beijing Institute of Technology Beijing 100081 P. R. China Complex System Intelligent Control and Decision Ministry of Education Beijing 100081 P. R. China

Task-oriented networked information system is an integrated information system which builds on multi-satellite networking to accomplish one or more tasks. In the background of emer- gency relief for applications, system working flow and response process are analyzed, and a timeliness effectiveness evaluation index system is constructed at multi-task level. The effectiveness is a measurement of promptness of information return. In evalua- tion process, system performance and tasks are associated, then an evaluation model based on efficacy function is established, and different evaluation criteria are selected for different tasks. A distributed simulation system is constructed, and the execution of task is decomposed. The simulation platform provides a comprehensive data source for evaluation. The results are easy to compare with each other, which reflects system time efficiency in different satellites networks and provides actual systems with basis and reference for design and application.

关键词： timeliness efficacy function space-based informationsystem simulation system.

The role of the DLPFC in inductive reasoning of MCI patients and normal agings:An fMRI study

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Science China(Life Sciences) 2009年第8期52卷 789-795页

作者： YANG YanHui1,3.LIANG PeiPeng2,3.LU ShengFu2,3.LI KunCheng1,3.& ZHONG Ning2,3.4 1 Xuanwu Hospital,Capital Medical University,beijing 100053.China 2 The International WIC institute,beijing University of {3.,beijing 100124,China 3.beijing Municipal Lab of Brain Informatics,beijing 100124,China 4 department of Life Science and Informatics,Maebashi institute of {3.,Maebashi 3.1-0816,Japan Xuanwu Hospital Capital Medical University Beijing 100053 China The International WIC institute Beijing University of Technology Beijing 100124 China beijing Municipal Lab of Brain Informatics Beijing 100124 China department of Life Science and Informatics Maebashi Institute of Technology Maebashi 371-0816 Japan

Previous studies of young people have revealed that the left dorsolateral prefrontal cortex(DLPFC) plays an important role in inductive *** fMRI experiment was performed in this study to examine whether the left DLPFC was involved in inductive reasoning of MCI patients and normal agings,and whether the activation pattern of this region was different between MCI patients and normal *** fMRI results indicated that MCI patients had no difference from normal agings in behavior performance(reaction time and accuracy) and the activation pattern of ***,the BOLD response of the DLPFC region for MCI patients was weaker than that for normal agings,and the functional connectivity between the bilateral DLPFC regions for MCI patients was significantly higher than for normal *** together,these results indicated that DLPFC plays an important role in inductive reasoning of agings,and the functional abnormity of DLPFC may be an earlier marker of MCI before structural alterations.

关键词： mild cognitive impairment functional MRI inductive reasoning

The Blow-up Locus of Heat Flows for Harmonic Maps

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Acta Mathematica Sinica,English Series 2000年第1期16卷 29-62页

作者： Jiayu Li institute of mathematics,Academia Sinica,beijing 100080,P.R.ChinaGang Tian {3.,MIT,Cambridge,MA 0213.,USA institute of mathematics Academia Sinica Beijing 100080 P.R. China department of mathematics MIT Cambridge USA

Let M and N be two compact Riemannian *** uk（x,t）be a sequence of strong stationary weak heat flows from M×R+ to N with bounded *** that uk→u weakly in H1.2（M×R+,N）and that ∑t is the blow-up set for a fixed t>*** this paper we first prove ∑t is an Hm-2-rectifiable set for almost all t ∈ R+.And then we prove two blow-up formulas for the blow-up set and the limiting *** the formulas,we can see that if the limiting map u is also a strong stationary weak heat flow,∑t is a distance solution of the（m-2）-dimensional mean curvature flow[1]. If a smooth heat flow blows-up at a finite time,we derive a tangent map or a weakly quasi-harmonic sphere and a blow-up set ∪t∑t×{t}.We prove the blow-up map is stationary if and only if the blow-up locus is a Brakke motion.

关键词： Heat flow Mean curvature flow Brakke motion Blow-up locus

Existence of Nonnegative Solutions to Singular Semi-positone Problems

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Acta Mathematicae Applicatae Sinica 2002年第3期18卷 523-528页

作者： Hong-zhou Wang, Li-hu Deng, Wei-gao Gedepartment of Applied mathematics, beijing institute of technology, {3. 100081, China department of Applied mathematics Beijing Institute of Technology Beijing China

In this paper we study a class of semi-positone singular boundary value problem. With prior bounds estimate and topology degree method, some existence results of nonnegative solution will be shown.

关键词： Semi-positone problem singularity Green function