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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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本文利用高斯函数的正整数阶导函数的一个性质,给出了一种探测信号奇异性的方法,得到了奇异点的位置,阶数α以及相应的平滑因子a和k,推导出了α满足的方程,对文献[8]的结论进行了推广.最后进行了数值试验,相对Mallat定理的10%的误差,取得了较好的效果. 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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A.P. Markeyev 《Journal of Applied Mathematics and Mechanics》2008,72(3):250-258
The stability in the first approximation of the rotation of a satellite about a centre of mass is investigated. In the unperturbed motion the satellite performs, in absolute space, three rotations around the normal to the orbital plane in a time equal to two periods of rotation of its centre of mass in the orbit (Mercury-type rotation). Three cases of such rotations are considered: the rotations of a dynamically symmetrical satellite and a satellite, the central ellipsoid of inertia of which is close to a sphere, in an elliptic orbit of arbitrary eccentricity, and the rotation of a satellite with three different principal central moments of inertia in a circular orbit. 相似文献
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Geometry of the Space of Phylogenetic Trees 总被引:2,自引:0,他引:2
We consider a continuous space which models the set of all phylogenetic trees having a fixed set of leaves. This space has a natural metric of nonpositive curvature, giving a way of measuring distance between phylogenetic trees and providing some procedures for averaging or combining several trees whose leaves are identical. This geometry also shows which trees appear within a fixed distance of a given tree and enables construction of convex hulls of a set of trees. This geometric model of tree space provides a setting in which questions that have been posed by biologists and statisticians over the last decade can be approached in a systematic fashion. For example, it provides a justification for disregarding portions of a collection of trees that agree, thus simplifying the space in which comparisons are to be made. 相似文献
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In this paper we introduce a theory of finite sets FST with a strong negation of the axiom of infinity asserting that every set is provably bijective with a natural number. We study in detail the role of the axioms of Power Set, Choice, Regularity in FST, pointing out the relative dependences or independences among them. FST is shown to be provably equivalent to a fragment of Alternative Set Theory. Furthermore, the introduction of FST is motivated in view of a non-standard development. MSC: 03E30, 03E35. 相似文献
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Nonlinear models are introduced to describe the nonequilibrium dynamics of social evolution. The difference between Western and Oriental culture, and their roles in the origin in the division of labour, are described by a behavioural model in information diffusion and learning competition. It shows a tradeoff between stability and diversity. The stochastic mechanism of social differentiation and the empirical evidence for this is discussed in a stochastic model of multi-staged development. It shows the breakdown of the Gaussian distribution during a transition. Finally, an ideal model of social bifurcation is given. 相似文献
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A. I. Budkin 《Algebra and Logic》2007,46(1):16-27
We fix a universal algebra A and its subalgebra H. The dominion of H in A (in a class M) is the set of all elements a ∈ A such that any pair of homomorphisms f, g: A → M ∈ M satisfies the following: if f and g coincide on H then f(a) = g(a). In association with every quasivariety, therefore, is
a dominion of H in A. Sufficient conditions are specified under which a set of dominions form a lattice. The lattice of dominions
is explored for down-semidistributivity. We point out a class of algebras (including groups, rings) such that every quasivariety
in this class contains an algebra whose lattice of dominions is anti-isomorphic to a lattice of subquasivarieties of that
quasivariety.
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Translated from Algebra i Logika, Vol. 46, No. 1, pp. 26–45, January–February, 2007. 相似文献
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The method of direct cutting-out consists of modeling of a finite body, in particular, with thin heterogeneities, using a
much simpler problem for a bounded or a partially bounded body with thin heterogeneities located in the same manner and the
presence of additional cracks or absolutely rigid inclusions of fairy large length, which are modeled by the boundary conditions
of a bounded body. The method is tested on the problems of antiplane deformation of a symmetrically loaded crack in a wedge
with free faces and an absolutely rigid inclusion placed with some tension in a wedge with restrained faces. For an elastic
inclusion, we construct generalized conditions of interaction, which enable us to unify the procedure of giving different
boundary conditions in the case of using the method of direct cutting-out. 相似文献
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The Effect of the Size of Carbon Fibers on the Physicomechanical Properties of Fluvis Composites 总被引:2,自引:0,他引:2
Shelestova V. A. Serafimovich V. V. Grakovich P. N. 《Mechanics of Composite Materials》2002,38(2):125-130
The effect of the size of carbon fibers on the thermophysical and strength characteristics of a Fluvis antifrictional composite, which is based on PTFE and modified Viscum fibers, is studied. It is found that, at a carbon-fiber length of about 100 m, a jump in the coefficient of linear thermal expansion occurs in all temperature ranges. An increase in the fiber length leads to a decrease in the density, resistivity, and compression strength of the composite. 相似文献
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This paper addresses the robust counterparts of optimization problems containing sums of maxima of linear functions. These problems include many practical problems, e.g. problems with sums of absolute values, and arise when taking the robust counterpart of a linear inequality that is affine in the decision variables, affine in a parameter with box uncertainty, and affine in a parameter with general uncertainty. 相似文献
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Nikolai Yu. Bakaev 《BIT Numerical Mathematics》2000,40(1):1-23
We examine single step time discrete approximations to an abstract Cauchy problem considered in a pair of Banach spaces, of which one (space of solutions) is densely embedded in the other (space of initial data). The stability and error analysis of such discretizations is carried out. Our approach is applicable to the analysis of approximations to parabolic PDE problems in various pairs of function spaces arising from practical needs. In the final part of the paper, we present a possible application of our results for studying a semi-discrete version of a model initial-boundary value problem of heat conduction. 相似文献
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In a separable Hilbert space we consider an evolution inclusion with a multivalued perturbation and evolution operators that are subdifferentials of a proper convex lower semicontinuous function depending on time. Along with the original inclusion, we consider a sequence of approximating evolution inclusions with the same perturbation and the evolution operators that are subdifferentials of the Moreau–Yosida regularizations of the original function. We show that the attainable set of the original inclusion, regarded as a multivalued function of time, is the uniform (in time) limit in the Hausdorff metric of the sequence of attainable sets of the approximating inclusions. As an application we consider an example of a control system with discontinuous nonlinearity. 相似文献