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On the new results of global attractive set and positive invariant set of the Lorenz chaotic system and the applications to chaos control and synchronization

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Science in China(Series F) 2005年第3期48卷 304-321页

作者： LIAO Xiaoxin 1, 2. 3 , FU Yuli 4.& XIE Shengli 4.1. Department of Control Science & Control Engineering, Huazhong university of Science & technology, {2. 4.0074. China 2. school of Automation,{4. of Science & technology, {2. 4.0070, China 3. school of Information, Central South university of Economy, Politics and Law, {2. 4.0064. China 4. school of Electronics & Information Engineering, South China university of technology, Guangzhou 51064., China Correspondence should be addressed to Liao Xiaoxin (email: xiaoxin_liao@***) 1. Department of Control Science & Control Engineering Huazhong University of Science & Technology 430074 Wuhan China 2. school of Automation Wuhan University of Science & Technology 430070 Wuhan China 3. school of Information Central South University of Economy Politics and Law 430064 Wuhan China 4. school of Electronics & Information Engineering South China University of Technology 510640 Guangzhou China

Constructing a family of generalized Lyapunov functions, a new method is proposed to obtain new global attractive set and positive invariant set of the Lorenz chaotic system. The method we proposed greatly simplifies the complex proofs of the two famous estimations presented by the Russian scholar Leonov. Our uniform formula can derive a series of the new estimations. Employing the idea of intersection in set theory, we extract a new Leonov formula-like estimation from the family of the estimations. With our method and the new estimation, one can confirm that there are no equilibrium, periodic solutions, almost periodic motions, wandering motions or other chaotic attractors outside the global attractive set. The Lorenz butterfly-like singular attractors are located in the global attractive set only. This result is applied to the chaos control and chaos synchronization. Some feedback control laws are obtained to guarantee that all the trajectories of the Lorenz systems track a periodic solution, or globally stabilize an unstable (or locally stable but not globally asymptotically stable) equilibrium. Further, some new global exponential chaos synchronization results are presented. Our new method and the new results are expected to be applied in real secure communication systems.

关键词： Lorenz chaotic system global attractive set positive invariant set globally exponential tracking globally exponential synchronization.

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Evidence of Positron Trapping into Defects in Zn-Doped GaAs

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wuhan university Journal of Natural Sciences 2003年第4A期8卷 1103-1106页

作者： Wang Zhu, Zheng Zi-yao, Su Ben-fa, Hu Wei-guo school of physics and {2., wuhan university , {4. 4.0072, hubei, China wuhan university

The defect properties in as-grown and deformed p-type GaAs with different concentration of dopants and different growth method have investigated by positron lifetime measurement. The result indicates that no positron trapping was observed in LEC-grown Zn-doped p-type GaAs. However, in HB- and FZ-grown Zn-doped GaAs, positron trapping into vacancy type defects was observed. In deformed samples, clusters were formed during deformation. Positron detected shallow positron traps and the dominant shallow positron traps were attributed to Zn acceptors in Zn-doped GaAs.

关键词： positron annihilation defect semiconductor deformation p-type GaAs

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Exploring non-equilibrium statistical ensembles

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Science Bulletin 2011年第34期56卷 3654-3660页

作者： BI Qiao & LIU Jie Department of physics, school of Science,{2. of technology, {4. 4.0070, China Department of physics School of Science Wuhan University of Technology

Since Gibbs synthesized a general equilibrium statistical ensemble theory, generalizing the Gibbsian theory to non-equilibrium phenomena has been a dream for some theorists. However, the status of the theory for the non-equilibrium ensemble formalism is not as well established as the Gibbsian ensemble theory. In this work, we explore the formalism behind the non-equilibrium statistical ensemble theory based on the sub-dynamic kinetic equation originating from the Brussels-Austin school and developed further by others. The key is establishing a similarity transformation between Gibbsian ensembles and the sub-dynamic ensemble. Using this way, we study a spin-Boson model with strong coupling. A reduced density operator for the canonical ensemble can be easily obtained and the relevant decoherence-free property is revealed.

关键词： subdynamics statistical ensemble non-equilibrium statistical physics

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Bose-Einstein Condensation in Linear Sigma Model at Hartree Approximation

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Communications in Theoretical physics 2008年第5期49卷 1261-1264页

作者： SHU Song~(1,+) LI Jia-Rong~2. Faculty of physics and Electronic technology,{2. {4.,{4. 4.0062.China2.Institute of Particle physics,Huazhong Normal {4.,{4. 4.0079,China Faculty of physics and Electronic technology Hubei University Wuhan 430062 China Institute of Particle physics Huazhong Normal University Wuhan 430079 China

The BEC of charged pions is investigated in the framework of O(4. linear sigma *** using Cornwall-Jackiw- Tomboulis formalism,we have derived the gap equations for the effective masses of the mesons at finite tempera-ture and finite isospin *** critical temperature and phase diagram of BEC are discussed in the non-chiral limitat Hartree approximation.

关键词： finite temperature field theory Bose-Einstein condensation phase transitions

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The Role of Calcium in Microstructural Refinement of AZ91 Magnesium Alloy

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Journal of wuhan university of technology(Materials Science) 2006年第4期21卷 45-47页

作者：刘生发 school of Materials Science and Engineering Wuhan University of Technology Wuhan 430070China

The effect of calcium addition on the microstructures of AZ91 magnesium alloy was investigated. It was found that a small amount of calcium in AZ91 allay produced a large decrease in the α- Mg grain size and the dispersed fine β-Mgt7 Alt2.phases. In addition, some Al4.a particles were found to exist in the AZ91 alloy containing 0.5wt% Ca. EDS analysis and water-quenched technique revealed that the grain-refining mechanism of calcium for the AZ91 alloys was mainly attributed to the role of restricting growth of calcium in the primary α-Mg crystals.

关键词： AZ91 magnesium alloy calcium microstructural refinement

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The feature study on the π and proton rapidity distributions at AGS, SPS and RHIC

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Science China(physics,Mechanics & Astronomy) 2009年第2期52卷 198-206页

作者： FENG ShengQin1,2.& YUAN XianBao1,3 1 College of Science, China Three Gorges university, Yichang 4.3002. China 2.{4. of {2. and technology,{4., wuhan 4.0072, China 3 Institute of Particle {2., Central China Normal university, wuhan 4.0070, China 1. College of Science China Three Gorges University Yichang 443002 China 2. school of physics and technology Wuhan University Wuhan 430072 China 3. Institute of Particle physics Central China Normal University Wuhan 430070 China

The features of nuclear stopping power and multi-hadron production systematically are studied by making an analysis of rapidity distributions of pion and proton at AGS, SPS and RHIC in this work. It is found that nuclear stopping power increases linearly with project rapidity yp at AGS and SPS, but that is not liner at RHIC. It is argued that the average rapidity loss is saturated at central rapidity region at RHIC. For pion distribution, it is found that the phase space of pion distribution distributes uniformly in the longitudinal direction,and a linear relationship of L with log s is given at AGS and SPS. Non-uniform flow model may explain the features of the distribution at AGS and SPS, but may not ex- plain those of at RHIC.

关键词： non-uniform flow model average rapidity loss baryon number density nuclear stopping power

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Photoluminescence of ZnO Nanorods Grown by Hydrothermal Method on Si Substrate

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wuhan university Journal of Natural Sciences 2009年第5期14卷 415-418页

作者： HU Ming,ZHANG Xia,MENG Xianquan school of physics and {2.,wuhan {4.,wuhan 4.0072.hubei,China school of physics and {2. Wuhan University Wuhan 430072 Hubei China

ZnO nanorods were grown on Si substrate by hydrothermal method under various reaction time （12. 2., and 36 h）, Zn^2. concentrations （0.01, 0.02. and 0.05 mol/L） and reaction temperatures （70-95 ~C）. Their photoluminescence （PL） tests were taken at room temperature. Nanorods grown under longer reaction times or higher temperatures can emit stronger UV light and depressed green light, suggesting better crystallization of ZnO nanorods. Higher Zn^2. concentration results in stronger green band emitting, whereas the UV peak is depressed with the Zn^2. concentration over 0.02.mol/L. This indicates that excessive interstitial Zn defects may be introduced into the nanorods in Zn-rich environment.

关键词： ZnO nanorods hydrothermal method photoluminescence

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Fabrication of Dense Ultrafine TiAl Alloys by Spark Plasma Synthesis from Mechanically Activiated Powders

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Journal of wuhan university of technology(Materials Science) 2007年第3期22卷 408-411页

作者：夏力 Department of Materials Engineering Wuhan University

Powder of Ti-4.at%Al alloy was synthesized through mechanical activation（MA） and then sintered and concurrently consolidated in a short sintering time of 900 s by using a spark plasma sintering（SPS） process. The XRD and SEM profiles show that the microstructures of TiAl alloys contained γ TiAl and small amount α-2.Ti3Al phase, whose amount can be controlled by the sintering temperature. The compacts retained the original fine-grained fully densified bodies by avoiding an excessively high sintering temperature. The alloys sintered at higher temperature with this process showed a coarser microstructure. So it is possible to produce dense nanostructured TiAl alloys by mechanically activated spark plasma sintering （MASPS） within a very short period of time.

关键词： titanium aluminides mechanical activation spark plasma sintering (SPS)

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Weak martingale Hardy spaces and weak atomic decompositions

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Science China Mathematics 2006年第7期49卷 912-921页

作者： HOU Youliang & REN Yanbo school of Mathematics and Statistics, wuhan university, {2. 4.0072, China Department of Mathematics & {4., Henan university of Science and technology, Luoyang 4.1003, China 1. school of Mathematics and Statistics Wuhan University Wuhan 430072 China 2. Department of Mathematics & physics Henan University of Science and Technology Luoyang 471003 China

In this paper we define some weak martingale Hardy spaces and three kinds of weak atoms. They are the counterparts of martingale Hardy spaces and atoms in the classical martingale Hp-theory. And then three atomic decomposition theorems for martingales in weak martingale Hardy spaces are proved. With the help of the weak atomic decompositions of martingale, a sufficient condition for a sublinear operator defined on the weak martingale Hardy spaces to be bounded is given. Using the sufficient condition, we obtain a series of martingale inequalities with respect to the weak Lp-norm, the inequalities of weak (p ,p)-type and some continuous imbedding relationships between various weak martingale Hardy spaces. These inequalities are the weak versions of the basic inequalities in the classical martingale Hp-theory.

关键词： martingale, weak Hardy space, weak atom, atomic decomposition.

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COLLECTIVELY COMPACT COMPOSITION OPERATOR SEQUENCES BETWEEN BERGMAN AND HARDY SPACES

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Acta Mathematica Scientia 2004年第2期24卷 206-212页

作者：王茂发刘培德 schoolofMathematicsandStatistics WuhanUniversityWuhan430072China

This paper studies the collective compactness of composition operator sequences between the Bergman and Hardy spaces. Some sufficient and necessary conditions involving the generalized Nevanlinna counting functions fo... 详细信息

关键词： Bergman space Hardy space composition operator collectively compact operator sequence

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