检索结果-南通市图书馆

Important Properties of Alternating Group A_6

在线全文

学校读者我要写书评

暂无评论

wuhan university Journal of Natural Sciences 1999年第4期4卷 404-408页

作者： HUANG Ben wen College of mathematics and Computer Science, wuhan university, wuhan 430072, china wuhan university College of Mathematics and Computer Science Wuhan China (GRID:grid.49470.3e) (ISNI:***)

By using electric computer machine, via computation method, we obtained some important properties of alternating group A \{6\} as below: 1) A \{6 \} has 501 subgroups in total, and for each subgroup we give its generators; 2) the index of A \{6\}'s subgroup can only be 1,2,3,4,5,6,8,9,10,12,18,24,36,60,360; 3) all subgroups of A \{6\} are separated into 22 conjugate classes, and the subgroups contained in each class are listed.

关键词： alternating group subgroup computer program

Numerical simulations and experimental investigations on transverse effects of two-wave mixing in a photovoltaic photorefractive crystal

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 856-863页

作者： CAI Xin1,2,LIU JinSong1 & WANG ShengLie1 1 wuhan National Laboratory for Optoelectronics,school of Optoelectronic Science and Engineering,Huazhong university of Science and Technology,wuhan 430074,china 2.school of Science,wuhan university of Technology,wuhan 430070,china wuhan National Laboratory for Optoelectronics School of Optoelectronic Science and Engineering Huazhong University of Science and Technology Wuhan China school of Science Wuhan University of Technology Wuhan China

The transverse effects of two Gauss waves mixing in a photovoltaic photorefractive crystal,i.e.,the dynamical evolutions of signal beam with different parameters,are traced numerically and *** the one-dimensional numerical simulations and two-dimensional experimental investigations show that the self-focusing effect of signal beam becomes more obvious as the intensity of pump beam and the angle between the signal and pump beams *** accordance with these results,the state of two Gaussian waves mixing is controllable.

关键词： numerical simulation experimental investigation two-wave mixing transverse effects Gaussian distribution

THEORETICAL ANALYSIS AND NUMERICAL SIMULATION OF TURBULENT FLOW AROUND SAND WAVES AND SAND BARS

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2009年第2期21卷 292-298页

作者： LIU Shi-he XIONG Xiao-yuan LUO Qiu-shi State Key Laboratory of Water Resource and Hydropower Engineering Science Wuhan University Wuhan 430072 China school of Water Resource and Hydropower Wuhan University Wuhan 430072 China Changjiang River Administration of Navigation Affairs MC Wuhan 430014 China

Natural rivers usually possess sand waves and sand bars. In this article, the rapid distortion theory was used to study the turbulent flow over sand waves. The results show that the pre-existing sheafing motion and upstream anisotropy of the turbulence flow would have significant effect on the turbulent structures, and hence the memory effect should be taken into consideration. Furthermore, the 2-D mathematical model was employed to simulate the unsteady flow around the Taiping Sand Bar in the lower reach of the Yangtze River and the time step effect on the unsteady flow simulation with the implicit scheme was discussed at the same time. The results show that the implicit scheme keeps effective until the time step reaches a certain number, and the calculated water levels and velocities are in agreement with the observed data.

关键词： sand wave sand-bar rapid distortion theory numerical simulation

Accountability Analysis of Electronic Commerce Protocols by Finite Automaton Model

在线全文

学校读者我要写书评

暂无评论

wuhan university Journal of Natural Sciences 2004年第3期9卷 293-295页

作者： Xie Xiao-yao 1,2 , Zhang Huan-guo 1 1. school of Computer, wuhan university, wuhan 430072, hubei, china 2. Institute of Network Technology, Guizhou university of Technology, Guiyang 550003, Guizhou, china school of Computer Wuhan University Wuhan Hubei China Institute of Network Technology Guizhou University of Technology Guiyang Guizhou China

The accountability of electronic commerce protocols is an important aspect to insures security of electronic transaction. This paper proposes to use Finite Automaton (FA) model as a new kind of framework to analyze the transaction protocols in the application of electronic commerce. Key words finite automaton - electronic commerce - nonrepudiation - information security CLC number TP 393. 08 Foundation item: Supported by the National Natural Science Foundation of china (66973034, 90104005, 60373087)Biography: Xie Xiao-yao (1952-), male, Professor, Ph. D candidate, research direction: information security.

关键词： finite automaton electronic commerce nonrepudiation information security

A New Location Precision Model for Multi-Static Over-the-Horizon Radar System

在线全文

学校读者我要写书评

暂无评论

wuhan university Journal of Natural Sciences 2010年第2期15卷 143-147页

作者： SONG Jun, ZHAO Zhengyu, ZHOU Chen school of Electronic Information, wuhan university, wuhan 430072, hubei, china school of Electronic Information Wuhan University Wuhan China

In this paper, a multi-static system working in an active way is made up of ionospheric oblique backscatter sounding system （IOBSS） and two separate receiving stations, which adopts discontinuous wave mechanism. We have advanced a new model that contains skywave condition to locate over-the-horizon targets. We use a single quasi-parabolic （QP） ionosphere model and an analytic ray-tracing program to obtain the coordinate registration （CR） index, which changes skywave group range to ground range. Also, IOBSS and other two receiving stations use this distance information to locate the target which is far away from the system. The analytic expression for the geometric dilution of precision （GDOP） under different station deployments are obtained, which shows GDOP is influenced by the system measurement precision, the stations＇ coordinates, and CR index. By computer simulation, we find that GDOP of isosceles right triangle deployment is smaller than that of line deployment and location precision will be improved with increasing base line length. The results indicate that this model is practicable with an acceptable range of error （less than 500 m under certain conditions in this paper）.

关键词： over-the-horizon radar (OTHR) multi-static coor-dinate registration target location

Analysis and Correction for Systematic Error of Ionospheric Monostatic System

在线全文

学校读者我要写书评

暂无评论

wuhan university Journal of Natural Sciences 2009年第3期14卷 245-251页

作者： WANG Feng, ZHAO Zhengyu, SU Fanfan school of Electronic Information, wuhan university, wuhan 430072, hubei, china school of Electronic Information Wuhan University Wuhan China

In the ionospheric monostatic system the echo is affected by systematic error. A real-time method using the special characters of direct wave existing in monostatic radar to correct systematic error is advanced. In the condition of large-amplitude direct wave, time delay of maximum amplitude of echo is considered as system time delay; in the condition of small-amplitude direct wave, the mathematical model of time delay error is built to approach after direct wave test. And a method using large-ampli- tude direct wave to correct phase distortion is advanced. It achieves good effect using this method in practice, which can improve the quality of sound result obviously.

关键词： ionospheric monostatic system systematic error time-delay error phase distortion direct wave

A New PAA Sol-Gel Method to Synthesis the Spinel LiMn_2O_4 Material for Li-ion Battery

在线全文

学校读者我要写书评

暂无评论

wuhan university Journal of Natural Sciences 2002年第1期7卷 97-101页

作者： Zhan Hui, Zhou Yun-hong  College of Chemistry and Molecular Sciences, wuhan university, wuhan 430072, hubei, china College of Chemistry and Molec. Sci. Wuhan University Wuhan 430072 Hubei China

A PAA sol-gel method, which is based on the chelate effect of PAA polymer, was developed for the synthesis of the spinel LiMn 2O 4 material. The pyrolysis process of the PAA-nitrate mixture precursor was investigated by TG and DTA analysis. It is found that the structure and electrochemical properties of the material are sensitive to the atmosphere employed in the synthesis process. Preliminary results show that the material thus prepared has a good electrochemical performance even at high charge and discharge current.

关键词： sol-gel PAA spinel material

Viscosity Solutions of Monotonic Functional Parabolic PDE

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2004年第4期 739-748页

作者： Wei An LIU school of mathematics and statistics,wuhan university,wuhan 430072,P.R.china Gang LU Department of mathematics,Central china Normal university,wuhan 430079,P.R.china

In this paper,by the technique of coupled solutions,the notion of viscosity solution is ex-tended to quasi-monotonic fully nonlinear parabolic equations with delay,which involves many modelsarising from optimal control theory,economy and finance,biology *** comparison,existence anduniqueness are *** the results are applied to the retarded Bellman equations.

关键词： Viscosity solution Functional PDE Technique of coupled solutions Retarded Bellman equations

A hybrid matching method for geospatial services in a composition-oriented environment

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第S1期53卷 213-220页

作者： LUO An 1,2,WANG YanDong 1,2 & CHEN ShengHua 2 1 State Key Laboratory of Software Engineering,wuhan university,wuhan 430072,china 2 State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing,wuhan university,wuhan 430079,china State Key Laboratory of Software Engineering Wuhan University Wuhan China State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan China

With the development of Internet and GIS,large volumes of spatial data,powerful computing resources and many spatial data processing functions are published in the form of Web *** suitable geospatial services in the composition-oriented environment is a crucial *** semantic Web provides a kind of technology to find and compose various service resources automatically through the *** paper proposes a hybrid method for the semantic matching of geospatial *** method includes two *** 1 puts forward a multi-level semantic matching approach,which matches single geospatial service at four levels:classification,input/output,precondition/effect and the quality of service(QoS).This multi-level matching approach makes single service matching quicker and more *** 2 puts forward a matching algorithm for a geospatial service chain based on the *** algorithm adopts a trace algorithm,taking account of the effect of the *** restricts the input/output parameters of the current service by the input/output parameters of service chain,pre-service and *** matches the atomic service dynamically in a composition-oriented environment,and accurately converts the abstract model of geospatial services into an executable geospatial service chain.A case study of the flood analysis for the Poyang Lake illustrates the effectiveness of our context-based matching method for geospatial services.

关键词： geospatial services semantic context composition service match