共查询到20条相似文献,搜索用时 750 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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本文从实验事实出发,对含有共轭三键的共轭高聚物——聚丁二炔的掺杂及电导的特点进行了详细的分析;对聚丁二炔晶体掺杂的机制进行了初步的探讨;从结构相变的角度出发,提出了一个掺杂模型,并从能量的角度估算了由于掺杂引起链段结构改变所需的能量,较好地解释了聚丁二炔晶体掺杂未取得成功的原因. 相似文献
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本文首先介绍了半群、群的定义,研究了自然数n取何值时,通过定义相应的代数运算,使得它的因子集构成半群、群,从而为半群的代数理论提供了一个有趣的实例. 相似文献
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K. I. Ivanov 《Mechanics of Composite Materials》1976,12(3):452-457
The "freezing" and "defreezing" temperature limits of an optically active material based on an epoxy resin have been experimentally investigated. A method of determining the mean value of the optical coefficient when the material is heated on the "freezing" temperature range is considered. The lower "defreezing" temperature limit has been experimentally established. The results of the investigation are presented in the form of graphs.Translated from Mekhanika Polimerov, No. 3, pp. 501–506, May–June, 1976. 相似文献
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在利用"准最优基"简化单纯形法的求解过程的基础上,采用matlab将"准最优基"方法程序化,并采用程序进行了模型.求解原采用两阶段法求解的线性规划问题,用"准最优基"方法,不必加入人工变量,改两阶段为一阶段,简化了求解过程,并针对只能将其目标函数系数为正的变量进基、约束条件都为正的局限性进行了探讨."准最优基"方法对目标函数的系数有正有负的情况,约束条件的系数有正有负的情况都适用.借助"bland法则"的思想,按下标顺序进基取代变量强度系数进基,得出了同样的结果,并对E.Beale的循环例子进行计算,一步得出最优解."准最优基"方法既可以提高运算速度,同时具有很好的适用性. 相似文献
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Let G be the group "ax + b" of affine transformations of the line and let U be a neighbourhood of 1 in G. It is proved that there is another neighborhood V of 1 such that to each finite sequence g1,...,gn V there corresponds a sequence of signs 1,...,n = ±1 with
U for k = 1,...,n. This implies that G satisfies the following analogue of the Dvoretzky-Hanani theorem: to each sequence
converging to 1 in G there corresponds a sequence of signs k = ±1 such that the infinite product
is convergent. 相似文献
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Let be a prime power and be a positive integer. A subspace partition of , the vector space of dimension over , is a collection of subspaces of such that each nonzero vector of is contained in exactly one subspace in ; the multiset of dimensions of subspaces in is then called a Gaussian partition of . We say that contains a direct sum if there exist subspaces such that . In this paper, we study the problem of classifying the subspace partitions that contain a direct sum. In particular, given integers and with , our main theorem shows that if is a subspace partition of with subspaces of dimension for , then contains a direct sum when has a solution for some integers and belongs to the union of two natural intervals. The lower bound of captures all subspace partitions with dimensions in that are currently known to exist. Moreover, we show the existence of infinite classes of subspace partitions without a direct sum when or when the condition on the existence of a nonnegative integral solution is not satisfied. We further conjecture that this theorem can be extended to any number of distinct dimensions, where the number of subspaces in each dimension has appropriate bounds. These results offer further evidence of the natural combinatorial relationship between Gaussian and integer partitions (when ) as well as subspace and set partitions. 相似文献
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The fourth order average vector field (AVF) method is applied to solve
the "Good" Boussinesq equation. The semi-discrete system of the "good" Boussinesq
equation obtained by the pseudo-spectral method in spatial variable, which is a
classical finite dimensional Hamiltonian system, is discretized by the fourth order
average vector field method. Thus, a new high order energy conservation scheme of
the "good" Boussinesq equation is obtained. Numerical experiments confirm that the
new high order scheme can preserve the discrete energy of the "good" Boussinesq
equation exactly and simulate evolution of different solitary waves well. 相似文献
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Houssein El Turkey 《Journal of Pure and Applied Algebra》2018,222(1):181-190
The complexity of a module is the rate of growth of the minimal projective resolution of the module while the z-complexity is the rate of growth of the number of indecomposable summands at each step in the resolution. Let () be the type II orthosymplectic Lie superalgebra of types B or D. In this paper, we compute the complexity and the z-complexity of the simple finite-dimensional -supermodules. We then give these complexities certain geometric interpretations using support and associated varieties. 相似文献
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"一站式"远程开放实验平台需要集成和整合分别多个来自不同厂商的实践教学软件,而不同的实践教学软件又有各自不同的用户系统与管理平台.针对这一情况,阐述了"一站式"远程开放实验平台的设计思路,并论述了"一站式"远程开放实验平台通过单点登录解决跨平台接口技术,通过Web Service方法实现平台对实践教学软件的数据的采集以及平台的权限设计与实现等关键技术. 相似文献