检索结果-南通市图书馆

1.55 μm Wavelength Operation of E_r^(3+) -Doped Optical Fiber Bistability

在线全文

学校读者我要写书评

暂无评论

wuhan University Journal of Natural {1.s 1999年第4期4卷 435-438页

作者： SONG Qian 1. ZHANG Yuan cheng 2.1. College of Electronics {1., wuhan University,{2., china.2. department of Physics, wuhan University,{2., china wuhan University College of Electronics Information Wuhan China (GRID:grid.49470.3e) (ISNI:***) wuhan University Department of Physics Wuhan China (GRID:grid.49470.3e) (ISNI:***)

An all optical all fiber optical bistability operation has been realized in an all fiber cavity consisted with Er doped fiber and optical fiber loop mirrors. The experimental bistability threshold is consistent w... 详细信息

关键词： optical nonlinearity optical bistability Er doped fiber all fiber device

LARGE DEVIATIONS FOR STATIONARY Φ-MIXING SEQUENCES IN τ-TOPOLOGY

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 1996年第2期17卷 149-158页

作者： Hu YIJUN department of Mathematics, {1. University,{2., china. department of Mathematics Wuhan University Wuhan 430072 China

The results of Bryc on large deviations for empirical measures of stationary Φ-mixing sequences are extended. Bryc states his results in the usual weak topology on the space ofprobability measures. In this paper, under somewhat weaker assumptions than those of Bryc,the author extends Bryc's results by taking the finer topology which is generated by the integralsover bounded measurable functions.

关键词： Large deviation Empirical measure Stationary sequence Φ-mixing τ-topology

Hierarchical Classification of Chinese Documents Based on N grams

在线全文

学校读者我要写书评

暂无评论

wuhan University Journal of Natural {1.s 2001年第Z1期6卷 416-422页

作者： Zhou Shui geng 1. Guan Ji hong 2. He Yan xiang 2.1. State Key Laboratory of Software Engineering, wuhan University, wuhan 430072,{2.2. School of Computer science, wuhan University, wuhan 430072, china State Key Laboratory of Software Engineering Wuhan University Wuhan China School of Computer science Wuhan University Wuhan China

We explore the techniques of utilizing N gram information to categorize Chinese text documents hierarchically so that the classifier can shake off the burden of large dictionaries and complex segmentation processing, and subsequently be domain and time independent. A hierarchical Chinese text classifier is implemented. Experimental results show that hierarchically classifying Chinese text documents based N grams can achieve satisfactory performance and outperforms the other traditional Chinese text classifiers.

关键词： Chinese text classification N grams feature selection hierarchical classification

Preparation and Characterization of Chitosan/Carboxymethylated Konjac Glucomannan Blend Films

在线全文

学校读者我要写书评

暂无评论

wuhan University Journal of Natural {1.s 2002年第1期7卷 107-112页

作者： Zheng Hua 1., Du Yu-min 2.1. {1. of Chemical Engineering, wuhan University of Technology, wuhan 430070, Hubei, china.2. College of Chemistry and Molecular sciences, wuhan University, wuhan 430072, Hubei, china wuhan University of Technology Department of Chemical Engineering Wuhan Hubei China (GRID:grid.162110.5) (ISNI:***) wuhan University College of Chemistry and Molecular Sciences Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***)

In order to improve the mechanical and water swelling properties of the chitosan (CS) film, a series of transparent films were prepared by blending 2.(weight) chitosan acetic acid solution with 1.5%(weight) carboxymethylated konjac glucomannan (CMKGM) aqueous solution according to predetermined ratio and drying at 30°C. The morphological structure, miscibility, thermal stability, mechanical properies, and swelling capacity of the blend films were studied by infrared (IR), X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron micrograph (SEM), and measurements of the mechanical properties and swelling properties. The results demonstrated that there was strong interaction and good miscibility between CS and CMKGM resulted from intermolecular hydrogen bonding and electrostatic force. The mechanical properties in dry state and wet state, thermostability, and water swelling properties of the blend films were obviously improved. The best values of the tensile strength in the dry and wet state achieved 89 MPa and 49 MPa, respectively, when the CMKGM content was 30%(weight). The CS/ CMKGM blend films provided promising biomedical applications.

关键词： Key words chitosan carboxymethylated konjac glucomannan blend films structure characterization

Mathematical stencil and its application in finite difference approximation to the Poisson equation

在线全文

学校读者我要写书评

暂无评论

science{1.Mathematics 2005年第10期48卷 1421-1429页

作者： FENG Hui~1.ZHANG Baolin~(1.2. & LIU Yang~1.1. {1. of Mathematics,wuhan University,wuhan 430072,china.2. Laboratory of Computational Physics,Institute of Applied Physics and Computational Mathematics,Beijing 1.0088. china 1. department of Mathematics Wuhan University 430072 Wuhan China 2. Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics 100088 Beijing China

The concept of mathematical stencil and the strategy of stencil elimination for solving the finite difference equation is presented, and then a new type of the iteration algorithm is established for the Poisson equation. The new algorithm has not only the obvious property of parallelism, but also faster convergence rate than that of the classical Jacobi iteration. Numerical experiments show that the time for the new algorithm is less than that of Jacobi and Gauss-Seidel methods to obtain the same precision, and the computational velocity increases obviously when the new iterative method, instead of Jacobi method, is applied to polish operation in multi-grid method, furthermore, the polynomial acceleration method is still applicable to the new iterative method.

关键词： mathematical stencil, stencil elimination, Poisson equation, finite difference, iterative algorithm,parallelism.

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

在线全文

学校读者我要写书评

暂无评论

Journal of wuhan University of Technology(Materials {1.) 2007年第3期22卷 408-411页

作者：夏力 department of Materials Engineering Wuhan University

Powder of Ti-46at%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)

SOME BOUNDARY INCREASING PROPERTIES OF HARMONIC FUNCTIONS IN LIPSCHITZ DOMAIN

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 1996年第2期17卷 159-166页

作者： ZHANG YIPING department of Mathematics, {1. University,{2., china.Project supported by the National Natural science Foundation of china. wuhan UNIV DEPT MATH WUHAN 430072 PEOPLES R CHINA

The object of this paper is to study the non-tangential increasing properties of positiveharmonic function u in Lipschitz domain by means of Martin representation theory. A necessaryand sufficient condition of the control of growth of u near any fixed boundary point is obtained.It is shown that the non-tangential increasing degree of u near a boundary point is exactlythe local degree of its representation measure with respect to the harmonic measure. Someexamples are given.

关键词： Martin representation Harmonic function Harmonic measure

Locating the Polar Cap Boundary of Postnoon Sector from Observations of 630.0 nm Auroral Emission at Zhongshan Station

在线全文

学校读者我要写书评

暂无评论

wuhan University Journal of Natural {1.s 2002年第1期7卷 59-64页

作者： Liu Li-gang 1, Ai Yong 1, Liu Rui-yuan 2. Yang Hui-gen 2.1. School of Electronic information, wuhan University,{2., Hubei, china.2. Polar Research Institute of china. Shanghai 2.012., china wuhan University School of Electronic Information Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Polar Research Institute of china Shanghai China (GRID:grid.418683.0) (ISNI:***)

We studied the ground observations of 630.0 nm auroral emission at Zhongshan Station to determine the polar cap boundary with the latitudinal profile of emission intensity. The open-closed field time boundary is assumed to lie at the boundary between polar rain and plasma sheet precipitation. We assume that nonprecipitation-dependent sources of 630.0 nm emission cause a spatially uniform luminosity in the polar cap and that auroral zone luminosity is also spatially uniform. Therefore we determine the location of the polar cap boundary of postnoon sector from the auroral emission data each time by finding the best fit of the observations to a step function in latitude and we produce a time series of the location of the polar cap boundary. The average error of the practice in the paper is less than 0.8 degree.

关键词： polar cap boundary aurora Zhongshan Station

NEW WAVELET BASES FOR NON－HOMOGENEOUS SYMBOLIC SPACE OpS1.1.m AND RELATED KERNEL－DISTRIBUTION SPACES

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2002年第4期23卷 551-562页

作者： YANG QIXIANGdepartment of Mathematics, {1. University,{2., china. department of Mathematics Wuhan University Wuhan 430072 China

This paper constructs several classes of new wavelet bases, which are unconditional bases for related operator spaces. Using these bases, the author analyzes non-homogeneous symbolic space OpSm1.1.and two related kernel-distribution spaces, and characterizes them in two wavelet coefficients spaces. Besides, some properties for singular integral operators are studied.

关键词： Wavelet bases Symbolic spaces Kernel-distribution spaces