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Basin filling algorithm for the circular packing problem with equilibrium behavioral constraints

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science china(information sciences) 2010年第5期53卷 885-895页

作者： LIU JingFa1& LI Gang2 1school of Computer and Software, nanjing university of information science & technology, nanjing 210044, china 2school of mathematics and physics, nanjing university of information science & technology, nanjing 210044, china school of Computer and Software Nanjing University of Information Science & Technology school of mathematics and physics Nanjing University of Information Science & Technology

With the background of the satellite module layout design, the circular packing problem with equilibrium behavioral constraints is a layout optimization problem and NP-hard problem in math. For lack of a powerful optimization method, this problem is hard to solve. The energy landscape paving (ELP) method is a class of stochastic global optimization algorithms based on the Monte Carlo sampling. Based on the quasiphysical strategy and the penalty function method, the problem is converted into an unconstrained optimization problem. Here by combining the improved ELP method, the gradient method based on local search and the heuristic configuration update mechanism, a new global search algorithm, basin filling algorithm, is put forward. The numerical results show that the proposed algorithm is effective to solving the circular packing problem with equilibrium behavioral constraints, and is easy to be popularized to other layout optimization problems.

关键词： equilibrium behavioral constraints packing problem layout optimization

A relative local variational principle for topological pressure

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science china mathematics 2010年第6期53卷 1491-1506页

作者： MA XianFeng1,CHEN ErCai2,3,& ZHANG AiHua2,4 1Department of mathematics,East china university of science and technology,Shanghai 200237,china 2school of mathematics and Computer science,nanjing Normal university,nanjing 210097,china 3Center of Nonlinear science,nanjing university,nanjing 210093,china 4College of mathematics and physics,nanjing university of Posts and Telecommunications,nanjing 210046,china Department of mathematics East China University of Science and Technology school of mathematics and Computer science Nanjing Normal University Center of Nonlinear science Nanjing University College of mathematics and physics Nanjing University of P

We define the relative local topological pressure for any given factor map and open cover,and prove the relative local variational principle of this *** precisely,for a given factor map π:(X,T)→(Y,S) between two topological dynamical systems,an open cover U of X,a continuous,real-valued function f on X and an S-invariant measure ν on Y,we show that the corresponding relative local pressure P(T,f,U,y) satisfies sup μ∈M(X,T){ hμ(T,U|Y)+∫X f(x)dμ(x) :πμ=ν}=∫Y P(T,f,U,y)dν(y),where M(X,T) denotes the family of all T-invariant measures on ***,the supremum can be attained by a T-invariant measure.

关键词： pressure conditional entropy relative local variational principle

Three-dimensional investigation of velocity skin effect in U-shaped solid armature

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Progress in Natural science:Materials International 2008年第12期18卷 1565-1569页

作者： Xin Li~a Chunsheng Weng~b a school of Power Engineering,nanjing university of science and technology,nanjing 210094,china b National Key Laboratory of Transient physics,nanjing university of science and technology,nanjing 210094,china school of Power Engineering Nanjing University of Science and Technology Nanjing 210094 China National Key Laboratory of Transient physics Nanjing University of Science and Technology Nanjing 210094 China

A three-dimensional transient computational model is applied to investigate the velocity skin effect (VSE) in a U-shaped solid arma- *** this model,current and heat transport in the armature can be evaluated *** results show a local concentration of current and joule heating at the interface,and significant damage occurs at the edges of the *** is also observed that there is significant enhanced heating at sharp comers because of the armature *** three-dimensional model can efficiently capture the salient features of the physical phenomena at the rail-armature interface,and contribute to the development of the armature design.

关键词： Electromagnetic launch Railgun U-shaped armature Velocity skin effect Erosion

Mechanical behaviors of alumina ceramics doped with rare-earth oxides

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Rare Metals 2010年第5期29卷 456-459页

作者： YAO Yijun LI Chuncheng WANG Ling JIANG Xiaolong QIU Tai school of mathematics and physics Nanjing University of Information Science & Technology Nanjing 210044 China College of Materials science and Engineering Nanjing University of Technology Nanjing 210009 China

The effects of three types of additives Y2O3, La2O3, and Sm2O3 on the sintering and mechanical behaviors of alumina ceramics were investigated. The bending strengths of alumina ceramics with Sm2O3 and Y2O3 additions were 455 and 439 MPa, respectively, higher than that with La2O3 addition. The fi＇acture toughness of the ceramics with Sm2O3 and Y2O3 were also higher than that with La2O3 addition. The fracture mode of rare earth oxides doped alumina ceramics exhibited obvious transgranular fractures as well as intergranular fracture. The results of research show that the improvement of bending strength and fracture toughness of alumina ceramics with rare earth oxides was achieved by refining the grain size and strengthening the grain boundary.

关键词： rare earths alumina doping mechanical properties microstructure

Characteristics of fMRI BOLD signal and its neurophysiological mechanism

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Progress in Natural science:Materials International 2007年第6期17卷 630-638页

作者： Zhao Xiaohu1,2, Wu Yigen3 and Guo Shengli3(1. College of Life sciences, Zhejiang university, Hangzhou 310058, china 2. Imaging Department of Tongji Hospital of Tongji university, Shanghai 200065, china 3. College of mathematics and physics, nanjing university of information science and technology, nanjing 210044, china) College of Life sciences Zhejiang University Hangzhou 310058 China Imaging Department of Tongji Hospital of Tongji university Shanghai 200065 China College of mathematics and physics Nanjing University of Information Science and Technology Nanjing 210044 China

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

关键词： functional magnetic resonance imaging blood oxygen level dependent nonlinear response neural electrophysiological activity.

Travelling wave solutions of a generalized Camassa-Holm-Degasperis-Procesi equation

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science china mathematics 2011年第3期54卷 555-572页

作者： DENG ShengFu1, GUO BoLing2 & WANG TingChun2,3 1Department of mathematics, Zhanjiang Normal university, Zhanjiang 524048, china 2Institute of Applied physics and Computational mathematics, Beijing 100088, china 3 College of Math and physics, nanjing university of information science and technology, nanjing 210044, china Department of mathematics Zhanjiang Normal University Institute of Applied physics and Computational mathematics College of Math and physics Nanjing University of Information Science and Technology

The travelling wave solutions of a generalized Camassa-Holm-Degasperis-Procesi equation ut-uxxt + (1 + b)umux = buxuxx + uuxxx are considered where b > 1 and m are positive integers. The qualitative analysis methods of planar autonomous systems yield its phase portraits. Its soliton wave solutions, kink or antikink wave solutions, peakon wave solutions, compacton wave solutions, periodic wave solutions and periodic cusp wave solutions are obtained. Some numerical simulations of these solutions are also given.

关键词： homoclinic orbits heteroclinic orbits peakon wave solutions compacton wave solutions periodic cusp wave solutions

Selection of unitary operations in quantum secret sharing without entanglement

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science china(information sciences) 2011年第9期54卷 1837-1842页

作者： XU Juan 1,CHEN HanWu 1,LIU WenJie 1,2 & LIU ZhiHao 1 1 school of Computer science and Engineering,Southeast university,nanjing 210096,china 2 school of Computer and Software,nanjing university of information science and technology,nanjing 210044,china school of Computer science and Engineering Southeast University school of Computer and Software Nanjing University of Information Science and Technology

We propose a substitute-Bell-state attack strategy for quantum secret sharing schemes without entanglement,as well as a definition of the minimum failure probability of such attack strategy.A quantitative analysis of security degrees corresponding to different unitary operations is also provided,when the secret sharing schemes without entanglement are stricken by substitute-Bell-state *** a result,the relation between the selection of unitary operations and the effect of substitute-Bell-state attack is shown,which can serve as an important guidance for the selection of unitary operations in designing and implementing quantum secret sharing schemes.

关键词： quantum secret sharing substitute-Bell-state attack unitary operation minimum failure probability

Complex transient dynamics of hidden attractors in a simple 4D system

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Chinese physics B 2015年第5期24卷 270-274页

作者：党小宇李春彪包伯成武花干 College of Electronic and information Engineering Nanjing University of Aeronautics and Astronautics school of Electronic & information Engineering Nanjing University of Information Science & Technology school of information science and Engineering Changzhou University school of Electronic and Optical Engineering Nanjing University of Science and Technology

A simple four-dimensional system with only one control parameter is proposed in this paper. The novel system has a line or no equilibrium for the global control parameter and exhibits complex transient transition behaviors of hyperchaotic attractors, periodic orbits, and unstable sinks. Especially, for the nonzero-valued control parameter, there exists no equilibrium in the proposed system, leading to the formation of various hidden attractors with complex transient dynamics. The research results indicate that the dynamics of the system shows weak chaotic robustness and depends greatly on the initial states.

关键词： transient dynamics hidden attractor equilibrium

Two possible mechanisms for vortex self-organization

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science china Earth sciences 2006年第2期49卷 202-211页

作者： LUO Zhexian2, ZHOU Xiuji1 & GAO Shouting3 1. Chinese Academy of Meteorological sciences, Beijing 100081, china 2. Department of Space information science, nanjing university of information science and technology, nanjing 210044, china 3. Institute of Atmospheric physics, Chinese Academy of sciences, Beijing 100029, china Department of Environmental science Nanjing University of Information Science and Technology Nanjing China Chinese Academy of Meteorological sciences Beijing China Institute of Atmospheric physics Chinese Academy of Sciences Beijing China

The vortex self-organization is investigated in this paper by four groups of numerical experiments within the framework of quasi-geostrophic model, and based on the experimental results two types of possible mechanisms for vortex self-organization are suggested. The meso-scale to-pography may enable separated vortices to merge into a larger scale vortex; and the interaction of meso-γ and meso-β scale systems may make separated vortices to self organize a typhoon-like vor-tex circulation.

关键词： vortex, self-organization, meso-scale topography, interaction of different scales.