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STABILITIES OF (A,B,C) AND NPDIRK METHODS FOR SYSTEMS OF NEUTRAL DELAY-DIFFERENTIAL EQUATIONS WITH MULTIPLE DELAYS

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Journal of Computational mathematics 2003年第3期21卷 375-382页

作者： Guo-feng Zhang (department of mathematics, lanzhou university, lanzhou 73.000, china) department of mathematics Lanzhou University Lanzhou 730000

Consider the following neutral delay-differential equations with multiple delays (NMDDE)where γ> 0, L, Mj and Nj are constant complex- value d×d matrices. A sufficient condition for the asymptotic stability of NMDDE system (0.1) is given. The stability of Butcher's (A,B,C)-method for systems of NMDDE are studied. In addition, we present a parallel diagonally-implicit iteration RK (PDIRK) methods(NPDIRK) for systems of NMDDE, which is easier to be implemented than fully implicit RK methods. We also investigate the stability of a special class of NPDIRK methods by analyzing their stability behaviors of the solutions of (0.1).

关键词： Neutral delay differential equations (A,B,C)-method RK method Parallel diagonally-implicit iteration RK method.

On adjacent-vertex-distinguishing total coloring of graphs

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Science china mathematics 2005年第3期48卷 289-299页

作者： ZHANG Zhongfu, CHEN Xiang’en, LI Jingwen, YAO Bing, LU Xinzhong & WANG Jianfang College of mathematics and Information Science, Northwest Normal university, lanzhou 730070, china department of Computer, lanzhou Normal College, lanzhou 730070, china Institute of Applied mathematics, lanzhou Jiaotong university, lanzhou 730070, china College of Information and Electrical Engineering, lanzhou Jiaotong university, lanzhou 730070, china Institute of Applied mathematics, Chinese Academy of Sciences, Beijing 100080, china 1. College of mathematics and Information Science Northwest Normal University 730070 Lanzhou China 2. department of Computer Lanzhou Normal College 730070 Lanzhou China 3. Institute of Applied mathematics Lanzhou Jiaotong University 730070 Lanzhou China 4. College of Information and Electrical Engineering Lanzhou Jiaotong University 730070 Lanzhou China 5. Institute of Applied mathematics Chinese Academy of Sciences 100080 Beijing China

In this paper, we present a new concept of the adjacent-vertex-distinguishing total coloring of graphs (briefly, AVDTC of graphs) and, meanwhile, have obtained the adjacent-vertex-distinguishing total chromatic number... 详细信息

关键词： graph, proper total coloring, adjacent-vertex-distinguishing total coloring, adjacent-vertex-distinguishing total chromatic number.

A NEW CHARACTERIZATION OF NBU CLASS OF LIFE DISTRIBUTIONS WITH APPLICATION

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Journal of Systems Science & Complexity 2003年第2期16卷 222-228页

作者： LI Xiaohu (department of mathematics, lanzhou university, lanzhou 73.000, china) department of mathematics Lanzhou University Lanzhou 730000 China

Assume an unreliable workstation performing jobs with a random service time, namely, it occasionally breaks down because of unexpected interruptions. As an interruption really occurs, the station is instantaneously repaired and the uncompleted job is restarted again from the beginning till a job is completed without being interrupted. The total service time is shown to be NBU if and only if the total time it takes to finish each job with interruptions is stochastically larger than that without them, irrespective of when and how the breakdowns occur. As an application, a nonparametric procedure is developed to test for the strict NBU property of the service time. Finally, some numerical simulations are presented as well.

关键词： NBU interruptions stochastically larger L-statistic

POSITIVE　SOLUTIONS　FOR　DIRICHLET　PROBLEMS　OF　SINGULAR　SEMILINEAR　ELLIPTIC　EQUATIONS

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Systems Science and Mathematical Sciences 1995年第3期8卷 203-208页

作者： CUI Shangbin(department of mathematics, lanzhou university, lanzhou 73.000, china) 兰州大学数学系甘肃兰州

ＰＯＳＩＴＩＶＥＳＯＬＵＴＩＯＮＳＦＯＲＤＩＲＩＣＨＬＥＴＰＲＯＢＬＥＭＳＯＦＳＩＮＧＵＬＡＲＳＥＭＩＬＩＮＥＡＲＥＬＬＩＰＴＩＣＥＱＵＡＴＩＯＮＳ￥ＣＵＩＳｈａｎｇｂｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉ... 详细信息

ＰＯＳＩＴＩＶＥＳＯＬＵＴＩＯＮＳＦＯＲＤＩＲＩＣＨＬＥＴＰＲＯＢＬＥＭＳＯＦＳＩＮＧＵＬＡＲＳＥＭＩＬＩＮＥＡＲＥＬＬＩＰＴＩＣＥＱＵＡＴＩＯＮＳ￥ＣＵＩＳｈａｎｇｂｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＬａｎｚｈｏｕＵｎｉｖｅｒｓ...

关键词： Singular semilinear elliptic equation Dirichlet problem positive solution.

The Regularity of Lagrangians f(x,ξ) = |ξ|^(α(x)) with Holder Exponents α(x)

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Acta Mathematica Sinica,English Series 1996年第3期12卷 254-261页

作者： Fan Xianling, department of mathematics lanzhou university lanzhou, 73.000 china department of mathematics lanzhou university lanzhou 730000 China

In this paper the regularity of the Lagrangians f（x,ζ）=|ζ|α（x）（11 α（x） α2α（x） is regular. This result gives a negative answer to a conjecture of V. Zhikov.

关键词： Lagrangians Integrals Sobolev spaces Regularity

THE CLAR FORMULAS OF REGULAR t-TIER STRIP BENZENOID SYSTEMS

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Systems Science and Mathematical Sciences 1995年第4期8卷 327-337页

作者： ZHANG Heping(department of mathematics,lanzhou university,lanzhou 73.000,china) 兰州大学数学系甘肃兰州

ＴＨＥＣＬＡＲＦＯＲＭＵＬＡＳＯＦＲＥＧＵＬＡＲｔ－ＴＩＥＲＳＴＲＩＰＢＥＮＺＥＮＯＩＤＳＹＳＴＥＭＳＴＨＥＣＬＡＲＦＯＲＭＵＬＡＳＯＦＲＥＧＵＬＡＲｔ－ＴＩＥＲＳＴＲＩＰＢＥＮＺＥＮＯＩＤＳＹＳＴＥＭＳ￥ＺＨＡＮＧ... 详细信息

ＴＨＥＣＬＡＲＦＯＲＭＵＬＡＳＯＦＲＥＧＵＬＡＲｔ－ＴＩＥＲＳＴＲＩＰＢＥＮＺＥＮＯＩＤＳＹＳＴＥＭＳＴＨＥＣＬＡＲＦＯＲＭＵＬＡＳＯＦＲＥＧＵＬＡＲｔ－ＴＩＥＲＳＴＲＩＰＢＥＮＺＥＮＯＩＤＳＹＳＴＥＭＳ￥ＺＨＡＮＧＨｅｐｉｎｇ（Ｄｅｐａｒｔｍｅｎｔ...

关键词： Benzenoid system perfect matching Clar formula.

Seasonal changes of endogenous ABA and cytokinins in environmental adaptation of different ecotypes of reed plants

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Journal of Environmental Sciences 1995年第4期7卷 449-454页

作者： Wang Hongliang , Zhang Chenglie(department of Biology, lanzhou university , lanzhou 73.000 , china)

ＳｅａｓｏｎａｌｃｈａｎｇｅｓｏｆｅｎｄｏｇｅｎｏｕｓＡＢＡａｎｄｃｙｔｏｋｉｎｉｎｓｉｎｅｎｖｉｒｏｎｍｅｎｔａｌａｄａｐｔａｔｉｏｎｏｆｄｉｆｆｅｒｅｎｔｅｃｏｔｙｐｅｓｏｆｒｅｅｄｐｌａｎｔｓＷａｎｇＨｏｎｇｌ... 详细信息

ＳｅａｓｏｎａｌｃｈａｎｇｅｓｏｆｅｎｄｏｇｅｎｏｕｓＡＢＡａｎｄｃｙｔｏｋｉｎｉｎｓｉｎｅｎｖｉｒｏｎｍｅｎｔａｌａｄａｐｔａｔｉｏｎｏｆｄｉｆｆｅｒｅｎｔｅｃｏｔｙｐｅｓｏｆｒｅｅｄｐｌａｎｔｓＷａｎｇＨｏｎｇｌｉａｎｇ，ＺｈａｎｇＣｈｅｎｇｌｉ...

关键词： ABA cytokinin ecotype environmental adaptation Phragmites communis T.

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.

STUDY ON THE IMMOBILIZATION OF PAPAIN WITH A MACROPOROUS BEAD CARRIER OF COPOLYMER CONTAINING MONOMER UNITS OF NAMINOETHYL ACRYLAMIDE AND VINYL ALCOHOI

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Chinese Journal of Polymer Science 2000年第1期18卷 25-31页

作者： Yan-feng Li Jun-rong Li Lian-di Fu Yao-zeng Li department of Chemistry, lanzhou university, lanzhou 73.000, china Gansu Natural Energy Research Institute, lanzhou 73.000, china Gansu Provincial Institute of Drug Control, lanzhou 73.000, china 兰州大学甘肃兰州甘肃自然能源所甘肃兰州 730000 甘肃省药检所甘肃兰州 730000

A kind of macroporous bead carrier of copolymer containing monomer units of N-aminoethyl acrylamide and vinylalcohol was synthesized, i.e. the MR-AA carrier. Papain was immobilized on the carrier using glutaraldehyde as the couplingagent. The enzymatic activity of the immobilized papain was compared with free papain using casein as a substrate, and theeffects of glutaraldehyde concentration, pH, temperature, time and papain amount added on the activity recovery were alsoinvestigated. The results show that the MR-AA carrier contains reactive primary amine groups, hydrophilic amido links andhydroxyl groups, as well as macroporous structures based on its matrix (MR-AV matrix), furthermore, the activity recoveryof papain in the immobilization could reach 48%/～58%. In comparison with free papain, the resulting immobilized papainexhibits a remarkable thermostability and better reusability.

关键词： Immobilization Papain Proteolytic enzyme Macroporous bead carrier