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钢管的订购和运输解答模型 被引量:3
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作者 邵铮 周天凌 +1 位作者 马健兵 《数学的实践与认识》 CSCD 北大核心 2001年第1期67-74,共8页
首先通过最短路算法简化了供需距离网络 ,去掉了铁路、公路等边的性质 ,使供需距离网络简化为一个供需运输价格表 .在此基础上构造了三个模型 :线性费用的网络流模型、改进的线性费用的网络流模型和具有非线性费用的网络流模型 .通过改... 首先通过最短路算法简化了供需距离网络 ,去掉了铁路、公路等边的性质 ,使供需距离网络简化为一个供需运输价格表 .在此基础上构造了三个模型 :线性费用的网络流模型、改进的线性费用的网络流模型和具有非线性费用的网络流模型 .通过改进传统的最小费用最大流算法 ,解决了本题的非线性费用网络流模型 。 展开更多
关键词 运输问题 网络流 树形网络 分支定界 钢管 订购 最小费用流
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县级电视台新闻采访工作的创新探析 被引量:2
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作者 《新媒体研究》 2016年第22期103-104,共2页
做好县级电视台新闻采访工作,关系到新闻节目的质量,也关系到党和政府宣传工作的覆盖面、影响力。而随着经济社会的不断发展,县级电视台新闻采访工作面临着巨大挑战,只有因势而变、顺势而为,尊重事物发展的客观规律,才能在激烈的竞争中... 做好县级电视台新闻采访工作,关系到新闻节目的质量,也关系到党和政府宣传工作的覆盖面、影响力。而随着经济社会的不断发展,县级电视台新闻采访工作面临着巨大挑战,只有因势而变、顺势而为,尊重事物发展的客观规律,才能在激烈的竞争中获得话语权和影响力。文章分析了目前县级电视台新闻采访工作存在的问题,探析了问题产生的原因,提出了新闻采访工作创新的方法。 展开更多
关键词 县级电视台 采访 创新 思维模式
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Elementary Waves of Two-dimensional Steady Isentropic Flow 被引量:2
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作者 张同 《Tsinghua Science and Technology》 SCIE EI CAS 1997年第3期103-108,共6页
A self similar solution is developed for two dimensional, steady, isentropic and inviscid flow. Some fundamental properties are clarified for centered simple waves R and shock waves S. The present paper provides furth... A self similar solution is developed for two dimensional, steady, isentropic and inviscid flow. Some fundamental properties are clarified for centered simple waves R and shock waves S. The present paper provides further theoretical analysis to clarify the results obtained by Glimm et al. using theoretical and computational methods. 展开更多
关键词 self similar solution rarefaction wave shock wave isentropic flow
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Interaction of Waves in Two-dimensional Steady Isentropic Flow 被引量:1
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作者 张同 《Tsinghua Science and Technology》 SCIE EI CAS 1997年第3期109-113,共5页
The Euler equations for two dimensional, steady, isentropic, and inviscid flow are considered. All the elementary waves are classified into incoming and outgoing waves under the assumption that there is a singular po... The Euler equations for two dimensional, steady, isentropic, and inviscid flow are considered. All the elementary waves are classified into incoming and outgoing waves under the assumption that there is a singular point in the configuration of the solution.The interactions of at most two incoming waves are dealt with in this paper, and all six kinds of configurations for the solutions are obtained. They are the Mach reflection (one kind), the shock wave S transmits contact discontinuity J (two kinds), the overtaking of two incoming shock waves (two kinds), and the collision of two incoming shock waves (one kind). 展开更多
关键词 rarefaction wave shock wave interaction of waves Mach reflection
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THE GLOBAL SMOOTH SOLUTION FOR HIGH-DIMENSIONAL HYPERBOLIC SYSTEMS
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作者 张同 《Acta Mathematica Scientia》 SCIE CSCD 1994年第3期241-251,共11页
The Cauchy problem of high-dimensional hyperbolic systems of nonlinear equations with initial data have been considered. Under certain assumptions on the eigenvalues of the nonlinear systems and the initial data, we g... The Cauchy problem of high-dimensional hyperbolic systems of nonlinear equations with initial data have been considered. Under certain assumptions on the eigenvalues of the nonlinear systems and the initial data, we get two theorems about the existence of global smooth solutions. 展开更多
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