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NONLINEAR STABILITY OF VISCOUS SHOCK WAVES FOR ONE-DIMENSIONAL NONISENTROPIC COMPRESSIBLE NAVIER–STOKES EQUATIONS WITH A CLASS OF LARGE INITIAL PERTURBATION

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Acta Mathematica Scientia 2018年第3期38卷 973-1000页

作者： Shaojun TANG Lan zhang school of mathematics and statistics wuhan university school of mathematics and statistics Wuhan University

We study the nonlinear stability of viscous shock waves for the Cauchy problem of one-dimensional nonisentropic compressible Navier–Stokes equations for a viscous and heat conducting ideal polytropic gas. The viscous shock waves are shown to be time asymptotically stable under large initial perturbation with no restriction on the range of the adiabatic exponent provided that the strengths of the viscous shock waves are assumed to be sufficiently *** proofs are based on the nonlinear energy estimates and the crucial step is to obtain the positive lower and upper bounds of the density and the temperature which are uniformly in time and space.

关键词： One-dimensional nonisentropic compressible Navier–Stokes equations viscous shock waves nonlinear stability large initial perturbation

Texture Preserving Denoising Method Combining Total Variation and Wavelet Shrinkage

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wuhan university Journal of Natural Sciences 2010年第1期15卷 31-35页

作者： zhang Tao,FAN Qibin school of mathematics and statistics,wuhan university,wuhan 4.0072,Hubei,china school of mathematics and statistics Wuhan University Wuhan China

In this paper,we propose a new image denoising method that combines total variation（TV） method and wavelet shrinkage. In our method,a noisy image is decomposed into subbands of LL,LH,HL,and HH in wavelet domain. LL subband contains the low frequency coefficients along with less noise,which can be easily eliminated using TV-based method. More edges and other detailed information like textures are contained in the other three subbands,and we propose a shrinkage method based on the local variance to extract them from high frequency noise. Experimental results show that this method retains the edges and textures very well while removing noise.

关键词： wavelet total variation texture local variance threshold

Criteria for Regularity of Elliptic Diffusion Processes and It’s Application

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wuhan university Journal of Natural Sciences 2005年第2期10卷 347-350页

作者： LI Bo 1,2 , zhang Xiao-min 3 1.school of mathematics and statistics,Huazhong Normal university,wuhan 430079,Hubei,china 2.school of mathematics and statistics, wuhan university, wuhan 4.0072, Hubei, china 3.Faculty of Science,Ningbo university,Ningbo 315211,Zhejiang, china Huazhong Normal university School of Mathematics and Statistics Wuhan Hubei China (GRID:grid.411407.7) (ISNI:***) wuhan university School of Mathematics and Statistics Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Ningbo university Faculty of Science Ningbo Zhejiang China (GRID:grid.203507.3) (ISNI:***)

The cone condition for x to be tegular for B under the elliptic diffusionprocess was proved. We also gave a necessary and sufficient condition for 0 to be regular for thornunder the elliptic diffusion process.

关键词： regular capacity thorn diffusion process

Some Probability Properties of Random Walk in Time-Random Environment

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wuhan university Journal of Natural Sciences 2004年第2期9卷 139-143页

作者： zhangXiao-min LiBo schoolofmathematicsandstatistics WuhanUniversityWuhan430072HubeiChina

A general formulation of the stochastic model for random walk in time-random environment and an equivalent definition is established in this paper. Moreover, some basic probability relations similar to the classical case which are very useful in the corresponding research of fractal properties are given. At the end, a typical example is provided to show the recurrence and transience. Key words random environment - random walk in timerandom environment - skew product Markov chain CLC number O 211.6 Foudation item: Supported by the National Natural Science Foundation of china (10371092) and Foundation of wuhan university.Biography: zhang Xiao-min (1977-), male, Ph. D candidate, research direction: stochastic processes and random fractal.

关键词： random environment random walk in timerandom environment skew product Markov chain

Sol-gel Preparation Copper-cadmium Halide DopedPhotochromic Glass Coating on Plate Glass

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International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 34-37页

作者： ShiyongLuo Jiayun zhang Jixiang Liu Metallurgy school, university of Science and Technology Beijing, Beijing 100083, china wuhan university of Technology, wuhan 430070, china Univ Sci & Technol Beijing Met Sch Beijing 100083 Peoples R China wuhan Univ Technol Wuhan 430070 Peoples R China

Copper-cadmium halide doped photochromic glass coating on plate glass has been prepared by a sol-gel process. The sample shows reversible photochromic effect. The results of X-ray diffraction (XRD) and infrared (IR) spectrum investigations indicate that the photochromic phase of tile coating is CuBr_xCl_(1-x), solid solution, and that the structure network of the coating is connected with the bonds of Si-O-Si, Si-O-B and Si-O-Al.

关键词： photochromic glass coating sol-gel photochromic phase, structure network

BIFURCATIONS OF PERIODIC ORBITS IN THREE-WELL DUFFING SYSTEM WITH A PHASE SHIFT

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Journal of Systems Science & Complexity 2011年第3期24卷 519-531页

作者： Jicai HUANG Han zhang school of mathematics and statistics Central China Normal University Wuhan 430079 China College of Information Technical Science Nankai University Tianjin 300071 China.

Bifurcations of periodic orbits of three-well Duffing system with a phase shift are investigated in detail. The conditions of the existence and bifurcations for harmonics, subharmonics （2-order, 3- order and m-order） and superharmonics under small perturbations are given by using second-order averaging method and Melnikov＇s method. The influence of the phase shift on the dynamics is also obtained.

关键词： Bifurcations Melnikov's method periodic orbits second-order averaging three-well Duffing system.

STUDY OF HYDRODYNAMIC FORCES OF SHIPS IN NARROW WATERWAY

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Journal of Hydrodynamics 2003年第4期15卷 113-117页

作者： zhang Xie-dong, Wu Xiu-heng school of Transportation, wuhan university of Technology, wuhan 430063, china school of Transportation Wuhan University of Technology Wuhan 430063 China

The collision of ships in narrow waterway may occur for a variety of *** hydrodynamic forces between two ships change the maneuvering characteristics of ships *** based on the boundary element method, this paper proposes a calculation method for hydrodynamicinteraction forces between ships under meeting and passing conditions in narrow waterway. Theresults from this method are compared with the existing results obtained from other theoreticalapproaches, and they are in good agreement.

关键词： collision of ships narrow waterway hydro-dynamic interaction boundaryelement method

CHARACTERIZATION OF REGENERATED CELLULOSE MEMBRANES HYDROLYZED FROM CELLULOSE ACETATE

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Chinese Journal of Polymer Science 2002年第4期20卷 369-375页

作者： Yun Chen Xiao-peng Xiong Guang Yang Li-na zhang Sen-lin Lei Hui Liang Electron Microscope Lab of Medical school, wuhan university wuhan 4.0072, china College of Chemistry and Molecular Sciences, wuhan university, wuhan 4.0072, china wuhan Univ Coll Chem & Mol Sci Wuhan 430072 Peoples R China wuhan Univ Sch Med Electron Microscope Lab Wuhan 430072 Peoples R China

A series of cellulose acetate membranes were prepared by using formamide as additive, and then were hydrolyzed in 4 wt% aqueous NaOH solution for 8 h to obtain regenerated cellulose membranes. The dependence of degree of substitution, structure, porous properties, solubility and thermal stability on hydrolysis time was studied by chemical titration, Fourier transform infrared spectroscopy, scanning electron microscopy, wide-angle X-ray diffraction, and differential scanning calorimetry, respectively. The results indicated that the pore size of the regenerated cellulose membranes was slightly smaller than that of cellulose acetate membrane, while solvent-resistance, crystallinity and thermostability were significantly improved. This work provides a simple way to prepare the porous cellulose membranes, which not only kept the good pore characteristics of cellulose acetate membranes, but also possessed solvent-resistance, high crystallinity and thermostability. Therefore, the application range of cellulose acetate membranes can be expanded.

关键词： hydrolysis cellulose acetate thermal stability regenerated cellulose membrane pore size solvent-resistance SEM

Integrability near the Boundary of the Poisson Integral of Some Singular Measures

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wuhan university Journal of Natural Sciences 2007年第3期12卷 395-401页

作者： SU Xiaofang zhang Yiping school of mathematics and statistics Wuhan UniversityWuhan 430072 Hubei China

We consider the Poisson integral u = P＊μ on the half-space R＋^N＋1 （ N 〉 1 ）（or on the unit ball of the complex plane） of some singular measureμ. If μ is an s-measure （0 〈 s 〈 N）, then some sharp estimates of the integration of the harmonic function u near the boundary are given. In particular, we show that fpr p〉1,∫R^Nu^p（x,y）dx- y^-τ （y〉0,τ =（N-s）（p-1））（Given for p〉1, RN f 〉 0 and g 〉 0, ＂ f-g ＂ will mean that there exist constants C1 and C2, such that C1f ≤ g ≤ CEf ）.

关键词： Poisson kemel Harmonic function s-measure