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Existence and Uniquenes of Limit Cycles for a Polynomial System

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Communications in Mathematical Research 1999年第2期 57-61页

作者： Liu Deming (Department of Mathematics, shenyang normal university, shenyang, 110031)

§１．ＩｎｔｒｏｄｕｃｔｉｏｎＦｏｒｔｈｅｆｏｌｏｗｉｎｇｐｏｌｙｎｏｍｉａｌｓｙｓｔｅｍｏｆｄｅｇｒｅｅｍ：ｄｘｄｔ＝ｆ１（ｘ，ｙ），ｄｙｄｔ＝ｆ２（ｘ，ｙ），（Ｅ）ｗｈｅｒｅｆ１（ｘ，ｙ）ａｎｄｆ２（ｘ，ｙ）ａｒ... 详细信息

§１．ＩｎｔｒｏｄｕｃｔｉｏｎＦｏｒｔｈｅｆｏｌｏｗｉｎｇｐｏｌｙｎｏｍｉａｌｓｙｓｔｅｍｏｆｄｅｇｒｅｅｍ：ｄｘｄｔ＝ｆ１（ｘ，ｙ），ｄｙｄｔ＝ｆ２（ｘ，ｙ），（Ｅ）ｗｈｅｒｅｆ１（ｘ，ｙ）ａｎｄｆ２（ｘ，ｙ）ａｒｅｐｏｌｙｎｏｍｉａｌｓｉｎｘａｎ...

关键词： Polynomial System Limit Cycle Existence and Uniqueness

Microstructures of an AlSi_7Mg alloy by near-liquidus casting

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Rare Metals 2007年第3期26卷 226-229页

作者： GAO Ming WANG Ping LU Guimin CUI Jianzhong School of Physics Science ＆ Technology Shenyang Normal University Shenyang 110034 China Key Laboratory for Microstructure ＆ properties of Advanced Materials Education Committee of Liaoning Province Shenyang Normal UniversityShenyang 110034 China Key Laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang 110004 China

Semi-solid ingots of an A1SiTMg alloy were obtained using the method of near liquidus casting. Their microstructures exhibit the characteristics of free, equiaxed, and non-dendrite, which are required for semi-solid forming. The influences of casting temperature, heat preservation time, and cooling rate on the microstructure were also investigated. The results show that in the temperature region near liquidus the grain size becomes small with a decrease in casting temperature. Prolonging the heat preservation time makes grain crassitude at the same temperature. And increasing the cooling rate makes grain fine. The microstructure of the alloy cast with iron mould is freer than that with graphite mould.

关键词： semi-solid near-liquidus casting AlSi7Mg alloy microstructure global grains

Research on the discrete variational method for a Birkhoffian system

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Chinese Physics B 2014年第6期23卷 328-332页

作者：刘世兴花巍郭永新 College of Physics Liaoning University College of Physics and Technology Shenyang Normal University

In this paper, we present a new integration algorithm based on the discrete Pfaff-Birkhoff principle for Birkhoffian systems. It is proved that the new algorithm can preserve the general symplectic geometric structures of Birkhoffian systems. A numerical experiment for a damping oscillator system is conducted. The result shows that the new algorithm can better simulate the energy dissipation than the R-K method, which illustrates that we can numerically solve the dynamical equations by the discrete variational method in a Birkhoffian framework for the systems with a general symplectic structure. Furthermore, it is demonstrated that the results of the numerical experiments are determined not by the constructing methods of Birkhoffian functions but by whether the numerical method can preserve the inherent nature of the dynamical system.

关键词： Birkhoff's equations discrete variational methods general symplectic structure discrete Birkhoff's equations

A New Admissibility Condition of Discrete-time Singular Systems with Time-varying Delays

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International Journal of Automation and computing 2012年第5期9卷 480-486页

作者： Yong-Yun Shao 1,3 Xiao-Dong Liu 1,2 Xin Sun 3 Zhan Su 4 1 Transportation Management College, Dalian Maritime university, Dalian 116026, China 2 Department of Mathematics, Dalian Maritime university, Dalian 116026, China 3 Department of Computer and Mathematics Teaching, shenyang normal university, shenyang 110034, China 4 Institute of Systems Science, Northeastern university, shenyang 110004, China Transportation Management College Dalian Maritime University Dalian China Department of Computer and Mathematics Teaching Shenyang Normal University Shenyang China Department of Mathematics Dalian Maritime University Dalian China Institute of Systems Science Northeastern University Shenyang China

This paper gives a novel delay-dependent admissibility condition of discrete-time singular systems with time-varying delays. For convenience, the time-varying delay is assumed to be the sum of delay lower bound and the integral multiples of a constant delay. Specially, if the constant delay is of unit length, the delay is an interval-like time-varying delay. The proposed admissibility condition is presented and expressed in terms of linear matrix inequality (LMI) by Lyapunov approach. Generally, the uncertainty of time-varying delay would lead to conservatism. In this paper, this critical issue is tackled by accurately estimating the time-varying delay. Consequently, the proposed admissibility condition is less conservative than the existing results, which is demonstrated by a numerical example.

关键词： Singular systems discrete-time delay-dependent admissibility time-varying delay

An improved group search optimizer for mechanical design optimization problems

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Progress in Natural Science:Materials International 2009年第1期19卷 91-97页

作者： Hai Shena,b,c,Yunlong Zhu a,Ben Niu a,b,Q.H.Wu d a Key Laboratory of Industrial Informatics,shenyang Institute of Automation,Chinese Academy of Sciences,shenyang 110016,China b Graduate School of the Chinese Academy of Sciences,Beijing 100049,China c College of Physics Science and Technology,shenyang normal university,shenyang 110034,China d Department of Electrical Engineering and Electronics,The university of Liverpool,Brownlow Hill,Liverpool,L69 3GJ,UK Key Laboratory of Industrial Informatics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang 110016 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China College of Physics Science and Technology Shenyang Normal University Shenyang 110034 China Department of Electrical Engineering and Electronics The University of Liverpool Brownlow Hill Liverpool L69 3GJ UK

This paper presents an improved group search optimizer(iGSO) for solving mechanical design optimization *** the proposed algorithm,subpopulations and a co-operation evolutionary strategy were adopted to improve the global search capability and convergence *** iGSO is evaluated on two optimization problems of classical mechanical design:spring and pressure *** experimental results are analyzed in comparison with those reported in the *** results show that iGSO has much better convergence performance and is easier to implement in comparison with other existing evolutionary algorithms.

关键词： Mechanical optimization problem GSO Constrained optimization problem

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中国古籍数字化进程和展望

图书情报工作 2002年第7期46卷 117-120页

作者：潘德利沈阳师范大学图书馆 110034

对中国台湾、香港、大陆的古籍数字化进程进行统计和介绍,并对古籍数字化工作的发展目标进行展望。

关键词：古籍数字化书目数据库全文数据库网络化中国大陆台湾省香港标准化

Development of Library Subject Service System in the Network Environment

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Development of Library Subject Service System in the Network...

2010 The 2nd International Conference on Industrial Mechatronics and Automation (ICIMA 2010)

作者： Hong Yue Department Of Library Information shenyang normal university shenyang China Chang Lin Department Of Foreign Languages Teaching shenyang normal university shenyang China

With the promotion of subject service,subject librarians have an urgent need to draw a network platform to conduct virtual *** article describes"Subject Service System"developed by the library of shenyang normal university,and describes the development process of the system from four aspects:system design,structure function,effects of system applications,and evaluation of system application.

关键词： Subject Service System Subject Service Subject Librarians

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美国国会图书馆藏中国古籍善本概略

图书情报工作 2003年第6期47卷 114-117页

作者：潘德利沈阳师范大学图书馆沈阳110034

在对美国国会图书馆所藏中国古籍善本书统计的基础上,探究他们搜集获得的途径及版本价值,展望美国国会馆藏中国古籍善本数字化与全球资源共享。

关键词：美国国会图书馆馆藏介绍中国古籍善本版本价值获取途径全球资源共享

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辛亥革命时期白话报刊生态考略

图书情报工作 2011年第19期55卷 18-21,96页

作者：吴瑾沈阳师范大学图书馆沈阳110034

清末社会,为考虑社会下层民众读书看报的问题,白话报刊如雨后春笋般不断涌现。维新时期国人自办的有5种,到1915年时全国大约出版170余种白话报刊。白话报刊的创办,为中国语言文化走向"言文合一",为启发民智,提升民族、民权意识,促进辛... 详细信息

清末社会,为考虑社会下层民众读书看报的问题,白话报刊如雨后春笋般不断涌现。维新时期国人自办的有5种,到1915年时全国大约出版170余种白话报刊。白话报刊的创办,为中国语言文化走向"言文合一",为启发民智,提升民族、民权意识,促进辛亥革命成功发挥了巨大作用。

关键词：辛亥革命白话报刊启蒙媒介