共查询到20条相似文献,搜索用时 125 毫秒
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基于GRA-DEA模型的有关农民收入的九城市的评价 总被引:1,自引:0,他引:1
王有文 《数学的实践与认识》2018,(6)
有关农民收入,文章以山西省九个城市为例进行了评价.首先用灰色关联分析法分析了2016年这些城市的有关数据,筛选出影响农民收入的主要因素;其次构建了指标体系,利用数据包络分析法对有关农民收入九个城市进行了DEA有效性评价;再次对非DEA有效的城市,借助投影公式探索了改进方法;最后得出了九城市分为两类的结论,提出了针对性的建议. 相似文献
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引入了T_λ算子,基于此算子,对模糊集的凸和拟凸的一些性质进行了研究,得出了一些结论。对模糊集的凸和拟凸的概念进行了拓展,引入了半凸模糊集,半拟凸模糊集,研究了半凸模糊集和半拟凸模糊集的性质。 相似文献
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由于自动控制理论提出了二阶微分方程的零解的全局稳定性,引起了不少数学工作者的研究,H.H.研究了方程组(1,1),得到了零解为全局稳定的充分条件,本文采用定性方法,研究了方程组(1,1)的零解为全局稳定的必要条件,并削弱了[1]中的充分条件,从而得到方程组(1,1)的零解为全局稳定的充要条件(定理 3——5).同时还研究了方程组(2,1)的零解为全局稳定的充要条件(定理6). 相似文献
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Fatiha Alabau 《Transactions of the American Mathematical Society》1998,350(12):4709-4756
We give a constructive method for giving examples of doping functions and geometry of the device for which the nonelectroneutral voltage driven equations have multiple solutions. We show in particular, by performing a singular perturbation analysis of the current driven equations that if the electroneutral voltage driven equations have multiple solutions then the nonelectroneutral voltage driven equations have multiple solutions for sufficiently small normed Debye length. We then give a constructive method for giving examples of data for which the electroneutral voltage driven equations have multiple solutions.
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Edmund R. Peay 《The Journal of mathematical sociology》2013,37(2):319-321
A simple modification of a method presented by Doreian (1974) adapts it for finding, in a network or “valued graph”, the maximum level paths which do not have cycles or repeated points and which have a specified maximum length. 相似文献
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The methods available for the estimation of the parameters, which determine the steady state conditions for the slow shear flow of polymers, under indifferent creep conditions have been considered, and the results of experiments carried out using a shear plastometer have been compared with calculations in which Boltzmann-Volterra equations with a memory characteristic have been used. The resolvent previously suggested in [3] has been employed in these latter equations. It has been shown that the equilibrium values for the modulus of rubber-like elasticity can be calculated from the results of experiments on unsteady creep states. 相似文献
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Geoff Smith Leigh Wood 《International Journal of Mathematical Education in Science & Technology》2013,44(1):125-132
The important issues in assessment practices for university undergraduates are identified. The way in which assessment can be used to enhance student learning, the impact of external factors on assessment methods and the barriers that inhibit change are discussed. The paper also discusses the various ways in which changes in assessment practices have have been implemented and studies that have been carried out to gauge the effect of different methods of assessment. 相似文献
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Phillip Bonacich 《The Journal of mathematical sociology》2013,37(3):203-224
Various extensions of the model are proposed to deal with a wider variety of conditions than are normally examined in experiments on exchange networks. With little or no modification, the model can predict power when exchange relations are unequal in value, when positions vary in the number of exchanges in which they can participate, and when three or more participants are required for a transaction to occur. A structural and algebraic theory of power in negatively connected exchange networks can be deduced from a few simple and plausible assumptions about how individuals make decisions. The model generates a set of equations. A typology of exchange networks follows from characteristics of the solution to these equations. There are four possibilities: the equations have a unique solution in which some positions have all the power; the equations have a unique solution in which all positions have equal power; the equations have an infinity of solutions, in which case power is undetermined by structural considerations; the equations have no solution, in which case power should be unstable. 相似文献
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Gerard M. Campbell Robert G. Cromley 《The Journal of the Operational Research Society》1991,42(9):793-802
Line simplification is a process by which unnecessary detail in cartographic data is eliminated. In the past, a variety of heuristics have been implemented to simplify lines. This paper describes practical algorithms which have been developed to provide optimal solutions. The line simplification problem is shown to have the special structure of an acyclic shortest-path problem. Three formulations are presented, which differ in the form of their objectives and/or constraints, and a solution algorithm is outlined for each formulation. Issues associated with implementation are addressed by using each algorithm to perform various degrees of simplification on a large example line. Possibilities for future research related to optimal line simplification are also discussed. 相似文献
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Cyclic cutwidth minimization problem (CCMP) consists of embedding a graph onto a circle such that the maximum cutwidth in a region is minimized. It is an NP-complete problem and for some classes of graphs, exact results of cyclic cutwidth have been proved in literature. However, no algorithm has been reported for general graphs. In this paper, a memetic algorithm is proposed for CCMP in which we have designed six construction heuristics in order to generate a good initial population and also local search is employed to improve the solutions in each generational phase. The algorithm achieves optimal results for the classes of graphs with known exact results. Extensive experiments have also been conducted on some classes of graphs for which exact results are not known such as the complete split graph, join of hypercubes, toroidal meshes, cone graph and some instances of Harwell-Boeing graphs which are a subset of public domain Matrix Market library. Trends observed in the experimental results for some of the classes of graphs have led to conjectures for cyclic cutwidth. 相似文献
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Adam Kozak Tomasz Głowacki Piotr Formanowicz 《Discrete Applied Mathematics》2013,161(13-14):1818-1827
Labeled graphs have applications in algorithms for reconstructing chains that have been split into smaller parts. Chain reconstruction is a common problem in biochemistry and bioinformatics, particularly for sequencing DNA or peptide chains. Labeled graphs (in the sense defined in this paper) have also the important structural property which allows to reduce the Hamiltonian path problem to Eulerian path problem. This work introduces a model and properties of a class of base-labeled graphs that unify the properties of labeled and free-labeled graphs (B?a?ewicz et al., 1999) [1]. It describes the basic relationships between those classes and some of their applications. It also introduces lexical graphs which are the superclass of de Bruijn graphs. Lexical graphs keep many properties of de Bruijn graphs which have a wide area of applications e.g. in mathematics, electronics and computing sciences. 相似文献
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Qiu Weiyuan 《数学学报(英文版)》1994,10(4):362-368
We show that the set of λ-values for which λ exp(z) does not have stable regions has Hausdorff dimension two, and that the set of λ-values for which λsin(z) does not have stable regions has a positive area.
Supported in part by Chinese NNSF. 相似文献
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E.J. Farrell 《Discrete Mathematics》1977,18(2):149-153
Chvátal gave a necessary condition for a partition to have a planar realization. It is of interest to find: (i) partitions which satisfy the condition of the theorem but have no planar realization, and also (ii) partitions which satisfy the condition and have only planar realizations. We give a list of all such partitions with 6, 7, 8 and 9 elements. We also give an algorithm for generating all graphs with a given partition, an algorithm for generating all subcompositions of a given composition and some general classes of partitions which have planar realizations only and some which have non-planar realizations only. 相似文献