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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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某类群的增广理想的基底及其商群的结构 总被引:1,自引:0,他引:1
本文研究了一类具有完全正规子群的有限群之增广理想及增广商群结构的问题.利用完全群的一些性质及数学归纳法,得到了此类群任意次增广理想的一组基底,并且解决了增广商群的结构问题. 相似文献
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本文提出了一类混合的非对称的GARCH模型(MAGARCH),利用随机差分方程的一些结果,研究了该模型的平稳性条件和尾行为,还讨论了MAGARCH(K;1,1)的矩的情况. 相似文献
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两类带有确定潜伏期的SEIS传染病模型的分析 总被引:2,自引:0,他引:2
通过研究两类带有确定潜伏期的SEIS传染病模型,发现对种群的常数输入和指数输入会使疾病的传播过程产生本质的差异.对于带有常数输入的情形,找到了地方病平衡点存在及局部渐近稳定的阈值,证明了地方病平衡点存在时一定局部渐近稳定,并且疾病一致持续存在.对于带有指数输入的情形,发现地方病平衡点当潜伏期充分小时是局部渐近稳定的,当潜伏期充分大时是不稳定的. 相似文献
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整环R称为ω-凝聚整环,是指R的每个有限型理想是有限表现型的.本文证明了ω-凝聚整环是v-凝聚整环,且若(RDTF,M)是Milnor方图,则在Ⅰ型情形,R是ω-凝聚整环当且仅当D和T都是ω-整环,且T_M是赋值环;对于Ⅱ-型情形,R是ω-凝聚整环当且仅当D是域,[F:D]<∞,M是R的有限型理想,T是ω-凝聚整环,且R_M是凝聚整环. 相似文献
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A set-covering problem is called regular if a cover always remains a cover when any column in it is replaced by an earlier column. From the input of the problem - the coefficient matrix of the set-covering inequalities - it is possible to check in polynomial time whether the problem is regular or can be made regular by permuting the columns. If it is, then all the minimal covers are generated in polynomial time, and one of them is an optimal solution. The algorithm also yields an explicit bound for the number of minimal covers. These results can be used to check in polynomial time whether a given set-covering problem is equivalent to some knapsack problem without additional variables, or equivalently to recognize positive threshold functions in polynomial time. However, the problem of recognizing when an arbitrary Boolean function is threshold is NP-complete. It is also shown that the list of maximal non-covers is essentially the most compact input possible, even if it is known in advance that the problem is regular. 相似文献
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This article is concerned with the existence of global attractor of a weakly dissipative generalized two-component μ-Hunter-Saxton(gμHS2) system with viscous terms.Under the period boundary conditions and with the help of the Galerkin procedure and compactness method, we first investigate the existence of global solution for the viscous weakly dissipative(gμHS2) system. On the basis of some uniformly prior estimates of the solution to the viscous weakly dissipative(gμHS2) system, we show that the semi-group of the solution operator {S(t)}t≥0 has a bounded absorbing set. Moreover, we prove that the dynamical system {S(t)}t≥0 possesses a global attractor in the Sobolev space H~2(S) × H~2(S). 相似文献
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We consider nonlinear finite-dimensional scalar-input control systems in the vicinity of an equilibrium.When the linearized system is controllable, the nonlinear system is smoothly small-time locally controllable: whatever and , the state can reach a whole neighborhood of the equilibrium at time T with controls arbitrary small in -norm.When the linearized system is not controllable, we prove that: either the state is constrained to live within a smooth strict manifold, up to a cubic residual, or the quadratic order adds a signed drift with respect to it. This drift holds along a Lie bracket of length , is quantified in terms of an -norm of the control, holds for controls small in -norm and these spaces are optimal. Our proof requires only regularity of the vector field.This work underlines the importance of the norm used in the smallness assumption on the control, even in finite dimension. 相似文献
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This paper focuses on the density of the minimal subspaces generated by a class of discrete linear Hamiltonian systems. It is shown that the minimal subspace is densely defined if and only if the maximal subspace is an operator; that is, it is single valued. In addition, it is shown that, if the interval on which the systems are defined is bounded from below or above, then the minimal subspace is non-densely defined in any non-trivial case. 相似文献
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In this paper, we find that the unbounded spaces can provide the work spaces where complicated asymptotic behavior appears in the solutions of the Cauchy problem of the porous medium equation. To overcome the difficulties caused by the nonlinearity of the equation and the unbounded solutions, we establish the propagation estimates, the growth estimates and the weighted – estimates for the solutions. 相似文献