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Short cycle structures for graphs on surfaces and an open problem of Mohar and Thomassen

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science china mathematics 2006年第2期49卷 212-224页

作者： REN Han & DENG Mo Department of mathematics, East china normal university, Shanghai 200062, china College of mathematics & Information science, Northwest normal university, Lanzhou 730070, china 1. Department of mathematics East China Normal University Shanghai 200062 China 2. College of mathematics & Information science Northwest Normal University Lanzhou 730070 China

In this paper we investigate cycle base structures of a (weighted) graph and show that much information of short cycles is contained in an MCB (i.e., minimum cycle base). After setting up a Hall type theorem for base-transformation, we give a sufficient and necessary condition for a cycle base to be an MCB. Furthermore, we show that the structure of MCB in a (weighted)graph is unique. The property is also true for those having a longest length (although much work has been down in evaluating MCB, little is known for those having a longest length). We use those methods to find out some unknown properties for short cycles sharing particular properties in (unweighted) graphs. As applications, we determine the structures of short cycles in an embedded graph and show that there exist polynomially bounded algorithms in finding a shortest contractible cycle and a shortest two-sided cycle provided such cycles exist. Those answer an open problem of B. Mohar and C. Thomassen.

关键词： cycle base facial cycle graph embedding.

Compactness of the commutators of parabolic singular integrals

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science china mathematics 2010年第10期53卷 2633-2648页

作者： CHEN YanPing1 & DING Yong2,3 1Department of mathematics and Mechanics,university of science and Technology Beijing,Beijing 100083,china 2school of Mathematical science,Beijing normal university,Beijing 100875,china 3Laboratory of mathematics and Complex Systems (BNU),Ministry of Education of china,Beijing 100875,china 1. Department of mathematics and Mechanics University of Science and Technology Beijing Beijing 100083 China2. School of Mathematical Science Beijing Normal University Beijing 100875 China3. Laboratory of Mathematics and Complex Systems (BNU) Ministry of Education of China Beijing 100875 China

In this paper,the authors prove that the commutator [b,T] of the parabolic singular integrals is a compact operator on Lp(Rn)(1 < p < ∞) if and only if b ∈ VMO(Rn,ρ).The result is substantial improvement and extens... 详细信息

关键词： parabolic singular integrals commutators compactness BMO VMO

Local Dissipativity and Attractors for the Evolutionary Superconductivity Problem

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Acta Mathematica Sinica,English Series 2001年第3期17卷 381-390页

作者： Hong Jun GAO Department of mathematics,nanjing normal university,nanjing 210024,P.R.china E-mail:gaohj@hotmail.comJi Shan FAN Department of Alathernatics,Suzhou university,Suzhou 215006.P.R.china Department of mathematics Nanjing Normal University Nanjing 210024 P. R. China

In this paper,under the Lorenz gauge,the global existence,local dissipativity and at- tractors of the evolutionary superconductivity problem which is a parabolic-hyperbolic system are obtained.

关键词： Superconductivity Attractor Ginzburg-Landau system

Key technologies of new malicious code developments and defensive measures in communication networks

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The Journal of china Universities of Posts and Telecommunications 2010年第4期17卷 69-73页

作者： LI Peng,WANG Ru-chuan ,ZHANG Wei College of computer,nanjing university of Posts and Telecommunications,nanjing 210003,china [a] College of computer Nanjing University of Posts Telecommunications Nanjing 210003 China

This article is focused on analyzing the key technologies of new malicious code and corresponding defensive measures in the large-scale communication networks. Based on description of the concepts and development of the malicious code, the article introduces the anti-analysis technology, splitting and inserting technology, hiding technology, polymorph virus technology, and auto production technology of the malicious code trends with intelligence, diversity and integration. Following that, it summarizes the security vulnerabilities of communication networks from four related layers aspects, according to the mechanisms of malicious code in the communication networks. Finally, it proposes rapid response disposition of malicious code attacks from four correlated steps： building up the network node monitoring system, suspicious code feature automation analysis and extraction, rapid active malicious code response technique for unknown malicious code, and malicious code attack immunity technique. As a result, it actively defenses against the unknown malicious code attacks and enhances the security performance of communication networks.

关键词： network security malicious code network attack and defense malicious code defense

A Feedback-Based Web Search Engine

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Wuhan university Journal of Natural sciences 2004年第5期9卷 561-568页

作者： ZHANG Wei-feng 1,2,3 , XU Bao-wen 2,3,4 , ZHOU Xiao-yu 2,3,4 1. Department of computer science and Engineering, nanjing university of Posts and Telecommunications, nanjing 210003, Jiangsu, china 2. Department of computer science and Engineering, Southeast university, nanjing 210096, Jiangsu, china 3. Jiangsu Institute of Software Quality, nanjing 210096 Jiangsu, china 4. The State Key Laboratory of Software Engineering, Wuhan university, Wuhan 430072, Hubei, china Department of computer science and Engineering Nanjing University of Posts and Telecommunications . Nanjing 210003 Jiangsu China

Web search engines are very useful information service tools in the Internet. The current web search engines produce search results relating to the search terms and the actual information collected by them. Since the selections of the search results cannot affect the future ones, they may not cover most people’s interests. In this paper, feedback information produced by the user’s accessing lists will be represented by the rough set and can reconstruct the query string and influence the search results. And thus the search engines can provide self-adaptability. Key words WWW - search engine - query reconstruction - feedback CLC number TP 311. 135.4 Foundation item: Supported by the National Natural science Fundation of china (60373066). National Grand Fundamental Research 973 Program of china (2002CB31200). Opening Foundation of State Key Laboratory of Software Engineering in Wuhan university, Opening Foundation of Jiangsu Key Laboratory of computer Information Processing Technology in Soochow universityBiography: ZHANG Wei-feng (1975-), male, Ph.D. research direction: artificial intelligence, search engine, data mining, network language.

关键词： WWW search engine query reconstruction feedback

JACOBI SPECTRAL APPROXIMATIONS TO DIFFERENTIALEQUATIONS ON THE HALF LINE

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Journal of Computational mathematics 2000年第1期18卷 95-112页

作者： Ben-yu Guo(Department of mathematics, Shanghai normal university, Shanghai 200234, china)(COM2MAC, Pohang university of science and Technology, Pohang, Korea) 上海师范大学上海 200234

Presents a study which investigated some Jacobi approximations which are used for numerical solutions of differential equations on the half line. Application of the approximations to problems on unbounded domains; Alg... 详细信息

关键词： Jacobi spectral approximations differential equations on the half line stability and convergence

Suppressing the disturbance in the transmission spectrum of Glan-Thompson-type prism polarizers

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Chinese Optics Letters 2010年第4期8卷 428-430页

作者：李红霞范吉阳苏富芳吴福全祝世宁 Department of Applied Physics nanjing university of science and Technology Department of Physics Nanjing University Department of Physics Southeast university Laser Research Institute Qufu normal university Department of Physics nanjing university

We analyze the random disturbance in the transmission of light through a spinning Glan-Thompsontype prism *** disturbance makes the dependence of the transmission on the rotation angle significantly deviates from the Malus cosine-squared law and severely spoils the output light *** vibration of the polarizer as it rotates combing the multi-beam-interference effect raises the disturbance. Further analysis reveals the sensitive dependence of the disturbance on the composing material of the prism gap,and the appropriate selection of such material can make the disturbance minimize to very desirable *** model results show quite good agreement with experiments.

关键词： Light sources Optical instruments Prisms

C^MC^N D-computable state

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science china(Physics,Mechanics & Astronomy) 2008年第9期51卷 1300-1307页

作者： LIU DongDong1,2 & DI YaoMin1 1 school of Physics & Electronic Engineering,Xuzhou normal university,Xuzhou 221116,china 2 school of mathematics & Physics science,Xuzhou Institute of Technology,Xuzhou 221008,china 1. school of Physics & Electronic Engineering Xuzhou Normal University Xuzhou 221116 China 2. school of mathematics & Physics science Xuzhou Institute of Technology Xuzhou 221008 China

The notions of D-computable state and D-concurrence are generalized to the CMCN system. A class of D-computable state on CMCN is given and the calculating method of the lower bound of D-concurrence is provided. Th... 详细信息

关键词： quantum entanglement entanglement of formation concurrence D-computable state

(2,n)secret sharing scheme for gray and color images based on Boolean operation

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science china(Information sciences) 2012年第5期55卷 1151-1161页

作者： DONG Lin 1,WANG DaoShun 1,LI ShunDong 2 & DAI YiQi 1 1 Department of computer science and Technology,Tsinghua university,Beijing 100084,china 2 school of computer science,Shaanxi normal university,Xi'an 710062,china 1. Department of computer science and Technology Tsinghua University Beijing 100084 China2. School of Computer Science Shaanxi Normal University Xi’an 710062 China

Traditional secret sharing (SS) schemes can reconstruct the secret precisely,but have high com-putation *** secret sharing (VSS) schemes use human visual system to reconstruct the secret without cryptographic computation,but have pixel expansion and loss of *** et *** a (2,n)-SS scheme for binary images based on Boolean operation,which has low computation complexity,no pixel expansion and the contrast is 1/*** this paper,we first construct an r runs (2,n)-SS scheme to improve the contrast of Wang et al.'s binary (2,n)-SS *** we present two approaches to construct r runs (2,n)-SS schemes for grayscale image and color *** two approaches are both based on Boolean operation,while one approach uses halftone technology and the other uses bit level *** proposed schemes have low computation complexity and almost ideal contrast.

关键词： secret sharing scheme Boolean operation halftone contrast