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A new scheme of digital communication using chaotic signals in MIMO channels

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science china(Information sciences) 2012年第10期55卷 2183-2193页

作者： MA HuanFei 1 & KAN HaiBin 2.1 school of Mathematical sciences,Soochow {2.,Suzhou 2.5006,china 2.school of computer science,Fudan {2.,shanghai 2.0433,china 1. school of Mathematical sciences Soochow University Suzhou 215006 China 2. school of computer {2. Fudan University Shanghai 200433 China

This paper proposes a new digital communication scheme,which uses chaotic signals based on the adaptive synchronization and parameter identification technique of chaotic systems reported *** to the multi signal character,this scheme combines the chaotic signal transmission with the MIMO channel technique in a wireless environment,which is different from the traditional chaotic communication *** a practical perspective,an outline of modulation,channel model,demodulation and non-coherent detection is ***,system performance is evaluated by simulations,and improvements on this scheme are also discussed.

关键词： chaotic modulation chaotic digital communication mapping parameters MIMO channel

Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

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science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

作者： PENG Miaojuan1 & XU Zhihong2.1. Department of Civil Engineering,shanghai university,shanghai 2.0072.china 2. school of Transportation Engineering,Tongji university,shanghai 2.0092.china 1. Department of Civil Engineering Shanghai University Shanghai 200072 China 2. school of Transportation Engineering Tongji University Shanghai 200092 China

To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.

关键词： asphalt pavement,permanent deformation,nonlinear viscoelastic-elastoplastic constitutive relationship,generalized Maxwell model,creep compliance.

Weighted composition operators between μ-Bloch spaces on the unit ball

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science china Mathematics 2005年第10期48卷 1349-1368页

作者： ZHANG Xuejun~1 & XIAO Jianbin~2.1. College of Mathematics and computer science,Hunan Normal {2.,Changsha 410006,china(email:xuejunttt@2.3. net) 2. The school of science,Hangzhou Dianzi {2.,Hangzhou 310037,china 1. College of Mathematics and computer science Hunan Normal University 410006 Changsha China 2. The school of science Hangzhou Dianzi University 310037 Hangzhou China

In this paper,necessary and sufficient conditions are given for the weighted composition operator T_(ψ,ψ) to be bounded or compact from the space β_μ to β_ν (or β_(μ,0) to β_(ν,0) ) on the unit ball of C^***... 详细信息

关键词： μ-Bloch space, weighted composition operator, boundedness, compactness.

Prediction for RNA planar pseudoknots

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Progress in Natural science:Materials International 2007年第6期17卷 717-724页

作者： Li Hengwu1,2. Zhu Daming1, Liu Zhendong1 and Li Hong2.1. school of computer {2. and Technology, Shandong university, Jinan 2.0100, china 2. Department of computer, Shandong Economic university, Jinan 2.0014, china) [a]school of computer {2. and Technology Shandong University Jinan China [b]Department of computer Shandong Economic University Jinan China

Based on m-stems and semi-extensible structure, a model is presented to represent RNA planar pseudoknots, and corresponding dynamic programming algorithm is designed and implemented to predict arbitrary planar pseudoknots and simple non-planar pseudoknots with O(n4) time and O(n3) space. The algorithm folds total 2.5 sequences in the Pseudobase database, and the test results indicate that the algorithm has good accuracy, sensitivity and specificity.

关键词： algorithm RNA secondary structure pseudoknot dynamic programming.

Kinetic theory of self-condensing vinyl polymerization

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science china Chemistry 2010年第12期53卷 2429-2439页

作者： ZHOU ZhiPing 1 & YAN DeYue 2.1 school of Materials science and Engineering,Jiangsu {2.,Zhenjiang 2.2.13,china 2.school of Chemistry and Chemical Engineering,shanghai Jiao Tong {2.,shanghai 2.02.0,china 1. school of Materials science and Engineering Jiangsu University Zhenjiang 212013 China2. School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China

This review introduces the kinetic theory of self-condensing vinyl polymerization (SCVP),including the SCVP of AB inimers,the SCVP with non-equal reactivity between A and B groups,the SCVP in the presence of a small amount of multifunctional initiators,also the SCVP of both inimers and *** analytical expressions of various molecular parameters for the resulting hyperbranched polymers,such as the molecular size distribution function,the average molecular weight,the polydispersity index and the degree of branching,are reviewed systematically.

关键词： kinetic theory self-condensing vinyl polymerization (SCVP) hyperbranched polymers

Spatial continuity incorporated multi-attribute fuzzy clustering algorithm for blood vessels segmentation

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science china(Information sciences) 2010年第4期53卷 752-759页

作者： HAO JuTao1*, ZHAO JingJing2.& LI MingLu3 1school of Optical-Electrical and computer Engineering, {2. of shanghai for science and Technology, shanghai 2.0093, china 2.epartment of Electrical Engineering, shanghai {2. of Electric Power, shanghai 2.0090, china 3Department of computer science and Engineering, shanghai Jiaotong {2., shanghai 2.02.0, china 1. school of Optical-Electrical and computer Engineering University of Shanghai for Science and Technology Shanghai 200093 China2. Department of Electrical Engineering Shanghai University of Electric Power Shanghai 200090 China3. Department of Computer Science and Engineering Shanghai Jiaotong University Shanghai 200240 China

A three-dimensional representation of vasculature can be extremely important in image-guided neurosurgery, pre-surgical planning. In this paper, a spatial continuity incorporated multi-attribute fuzzy clustering algorithm (MAFCM S) is proposed to segment entire blood vessels from TOF MRA images. This clustering method takes both the intensity information and the geometrical information into account, while most of the cur- rent clustering methods only deal with the former. In this method, a new dissimilarity measure, which integrates the intensity and the geometry shape dissimilarity, is introduced. Because of the presence of the geometrical information, the new measure is able to differentiate the pixels with similar intensity values within different geometrical shape structures. Experimental results show that the new algorithm can get better segmentation.

关键词： fuzzy c-means clustering scale space analysis spatial continuity blood vessel segmentation multi-attribute fuzzy clustering

Phase transition in the Zr_(60)Al_(15)Ni_(2.) bulk metallic glass subjected to rolling at room temperature

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science china(Technological sciences) 2006年第6期49卷 655-662页

作者： YAN Zhijie1, 2. LI Jinfu1, ZHOU Yaohe1 & WU Yanqing3 1. State Key Laboratory of Metal Matrix Composites, school of Materials science and Engineering, {2. Jiao Tong university, {2. 2.0030, china 2. school of Materials science and Engineering, Taiyuan university of science and Technology, Taiyuan 03002., china 3. school of Environmental science and Engineering, {2. Jiao Tong university, {2. 2.0030, china State Key Laboratory of Metal Matrix Composites School of Materials Science Engineering Shanghai Jiao Tong University Shanghai 200030 China school of Materials science Engineering Taiyuan University of Science Technology Taiyuan 030024 China school of Environmental science Engineering Shanghai Jiao Tong University Shanghai 200030 China

The microstructure evolution of the Zr60Al15Ni2. metallic glass during rolling at room temperature is investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC); high-resolution transmission electron microscopy (HREM). The results show that the values of full width at half maximum (FWHM) of the XRD patterns; exothermic enthalpy ΔH of DSC plots do not monotonically change with the variation of deformation degrees . As is not large than 2.%, the values of FWHM; ΔH are lower than that of the as-cast state. When reaches 30%, the values of FWHM; ΔH become larger than that of the as-cast state, while their values begin to decrease again as reaches about 85%. These results indicate that the reversible transitions between ordered; disordered atomic configurations occur during rolling, which is further verified by the HREM images. The reversible phase transition can be explained by the competition between the diffusion controlled reordering; shear-induced disordering during rolling.

关键词： metallic glasses, plastic deformation, phase transformations, shear bands.

Large-eddy simulations and vortex structures of turbulent jets in crossflow

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science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 118-132页

作者： GUAN Hui1,2.& WU ChuiJie2.1 school of Mechanical and Power Engineering,East china {2. of science and Technology,shanghai 2.02.7,china 2.Research Center for Fluid Dynamics,PLA {2. of science and Technology,Nanjing 2.1101,china 1. school of Mechanical and Power Engineering East China University of Science and Technology Shanghai 200237 China 2. Research Center for Fluid Dynamics PLA University of Science and Technology Nanjing 211101 China

Using the method of large-eddy simulation, the 3-dimensional turbulent jets in crossflow with stream-wise and transverse arrangements of nozzle are simulated, emphasizing on the dynamical process of generation and evolution of vortex structures in these flows. The results show that the basic vortex structures in literatures, such as the counter-rotating vortex pair, leading-edge vortices, lee-side vortices, hanging vortices, kidney vortices and anti-kidney vortices, are not independent physical substances, but local structures of the basic vortex structure of turbulent jets in crossflow-the 3-D stretching vortex rings originating from the orifice of the nozzle, which is discovered in this study. Therefore, the most important large-scale structures of turbulent jets in crossflow are unified to the 3-D vortex rings which stretch and twist in stream-wise and swing in transverse directions. We also found that the shedding frequencies of vortex rings are much lower than the one corresponding to the appearance of leading-edge and lee-side vortices in the turbulent jets.

关键词： turbulent jet in crossflow coherent structure large-eddy simulation

Superconductivity of small metal grains

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science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 431-441页

作者： ZHENG Renrong1 CHEN Zhiqian2.& ZHU Shunquan1,3 1. Department of Physics, shanghai Normal university, shanghai 2.02.4, china 2. Department of Physics, Southwest Normal university, Chongqing 400715, china 3. Department of computer and Electric Technology, shanghai Business school, shanghai 2.1400, china 1. Department of Physics Shanghai Normal University 200234 Shanghai China 2. Department of Physics Southwest Normal University 400715 Chongqing China 3. Department of computer and Electric Technology Shanghai Business School 201400 Shanghai China

The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.

关键词： size effect, superconductivity enhancements, small metallic grains.