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系统动力学在城市污水再生回用系统中的应用 总被引:5,自引:0,他引:5
用系统动力学方法研究了城市污水回用系统.首先分析了影响城市污水回用系统的诸多因素以及它们之间的相互关系,探讨了污水再生回用系统行为和结构的特点,确定了系统中因素之间的定量关系,建立了城市污水回用系统动力学(SD)模型,并介绍了模型的检验方法.同时给出了SD模型的具体应用实例,对西北地区的某一城市的污水回用进行了预测和分析,提出了符合该城市发展的污水回用方案. 相似文献
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提出了交通运输系统协调度的评价分析模型.从系统论的观点出发,提出了交通运输系统协调理论的概念,探讨了交通运输系统随时间而不断演化变迁的规律,给出了交通运输系统协调发展基本步骤;并根据协调学原理,讨论了交通运输系统的协调性问题,提出了系统协调发展模型,对交通运输子系统内部及子系统之间及系统整体的协调发展问题进行了研究,探讨了交通运输可持续发展的系统协调管理过程,为进一步研究交通运输系统的可持续发展奠定了基础. 相似文献
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从一个常见的不等式谈起,分析了多种证明方法,运用该不等式推导出了多个重要结论,对不等式进行了扩充和加强,解释了蕴含的意义,显示了该不等式的重要性和深刻性. 相似文献
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基于粗糙集的患者满意度评价模型及其实证分析 总被引:1,自引:0,他引:1
在文献阅读及实地调研的基础上,本文提出了患者满意度的定义,建立了影响患者满意度的指标体系,介绍了粗糙集的相关概念及利用粗糙集进行评价的步骤,提出了新的约简方法,构建了基于粗糙集的患者满意度评价模型并进行了实证分析,得出了影响患者满意度的关键指标,并计算了关键指标权重,对江西省十个医院进行了综合评价值的计算. 相似文献
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推广了RPG游戏中的一个难题,建立了相应的数学模型,给出了完善的解决方案,深化了现行的相关结果. 相似文献
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Two polyester-based polymer concretes with various volume content of diabase as an extender and aggregate are tested in creep
under compression at different stress levels. The phenomenological and structural approaches are both used to analyze the
experimental data. Common features of changes in the instantaneous and creep compliances are clarified, and a phenomenological
creep model which accounts for the changes in the instantaneous compliance and in the retardation spectrum depending on the
stress level is developed. It is shown that the model can be used to describe the experimental results of stress relaxation
and creep under repeated loading. Modeling of the composite structure and subsequent solution of the optimization problem
confirm the possibility of the existence of an interphase layer more compliant than the binder. A direct correlation between
the interphase volume content and the instantaneous compliance of the composite is revealed. It is found that the distinction
in nonlinearity of the viscoelastic behavior of the two polymer concretes under investigation can be due to the difference
in their porosity.
Submitted to the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000.)
Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 147–164, 2000. 相似文献
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K. Petras 《Constructive Approximation》1998,14(2):231-245
We consider error estimates for optimal and Gaussian quadrature formulas if the integrand is analytic and bounded in a certain
complex region. First, a simple technique for the derivation of lower bounds for the optimal error constants is presented.
This method is applied to Szeg?-type weight functions and ellipses as regions of analyticity. In this situation, the error
constants for the Gaussian formulas are close to the obtained lower bounds, which proves the quality of the Gaussian formulas
and also of the lower bounds. In the sequel, different regions of analyticity are investigated. It turns out that almost exclusively
for ellipses, the Gaussian formulas are near-optimal. For classes of simply connected regions of analyticity, which are additionally
symmetric to the real axis, the asymptotic of the worst ratio between the error constants of the Gaussian formulas and the
optimal error constants is calculated. As a by-product, we prove explicit lower bounds for the Christoffel-function for the
constant weight function and arguments outside the interval of integration.
September 7, 1995. Date revised: October 25, 1996. 相似文献
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Leonid Tolmatz 《Journal of Mathematical Analysis and Applications》2005,304(2):668-682
The double Laplace transform of the distribution function of the integral of the positive part of the Brownian bridge was determined by M. Perman and J.A. Wellner, as well as the moments of this distribution. The purpose of the present paper is to determine the asymptotics of this distribution for large values of the argument, and the corresponding asymptotics of the moments. 相似文献
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Güngör Gündüz 《The Journal of mathematical sociology》2013,37(3):167-187
In this work, mathematical models for the growth of the Ottoman and Roman Empires are found. The time interval considered for both cases covers the time from the birth of the empire to the end of the fast expansion period. These empires are assumed to be nonlinearly growing and self-multiplying systems. This approach utilizes the concepts of chaos theory, and scaling. The area governed by the empire is taken as the measure of its growth. It was found that the expansion of each empire on lands, seas, and on both (i.e., lands+seas) can be expressed by power laws. In the Ottoman Empire, the nonlinear growth power of total area is approximately equal to the golden ratio, and the nonlinear growth power of the expansion on lands is approximately equal to the square root of 2. In the case of the Romans, some numbers associated with the golden ratio, or the square root of 2, appear as the power of the nonlinear growth term. The appearance of both the golden ratio and the square root of 2 show that both empires had intention on achieving stability during their growth. 相似文献
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C. E. Ferreira A. Martin C. C. de Souza R. Weismantel L. A. Wolsey 《Mathematical Programming》1996,74(3):247-266
We investigate the problem of partitioning the nodes of a graph under capacity restriction on the sum of the node weights
in each subset of the partition. The objective is to minimize the sum of the costs of the edges between the subsets of the
partition. This problem has a variety of applications, for instance in the design of electronic circuits and devices. We present
alternative integer programming formulations for this problem and discuss the links between these formulations. Having chosen
to work in the space of edges of the multicut, we investigate the convex hull of incidence vectors of feasible multicuts.
In particular, several classes of inequalities are introduced, and their strength and robustness are analyzed as various problem
parameters change. 相似文献
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尽管PROMETHEE是当前最受欢迎的多准则决策方法之一,但在实践应用过程中,模型的应用范围与质量依然受制于指标权重问题。一些常用的赋权方法,不仅没有解决不确定权重问题,反而增加了决策风险。在偏序集相关定理的基础上,给出权重的定性信息即权重次序,由流出矩阵、流入矩阵和净流矩阵等定义,得到了PROMETHEE的偏序集表达形式。当流入和流出之和为常数时,证明了模型存在对偶性质。根据对偶性质,简化了PROMETHEE方法的分析步骤,删减模型冗余信息。应用偏序集表示的PROMETHEE,突破了模型没有具体权重便无法应用的思维定势,解决了模型赋权困难,增强了模型的鲁棒性,拓展了模型处理数据类型的范围。 相似文献
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Joydeep Dutta 《TOP》2005,13(2):185-279
During the early 1960’s there was a growing realization that a large number of optimization problems which appeared in applications
involved minimization of non-differentiable functions. One of the important areas where such problems appeared was optimal
control. The subject of nonsmooth analysis arose out of the need to develop a theory to deal with the minimization of nonsmooth
functions. The first impetus in this direction came with the publication of Rockafellar’s seminal work titledConvex Analysis which was published by the Princeton University Press in 1970. It would be impossible to overstate the impact of this book
on the development of the theory and methods of optimization. It is also important to note that a large part of convex analysis
was already developed by Werner Fenchel nearly twenty years earlier and was circulated through his mimeographed lecture notes
titledConvex Cones, Sets and Functions, Princeton University, 1951. In this article we trace the dramatic development of nonsmooth analysis and its applications
to optimization in finite dimensions. Beginning with the fundamentals of convex optimization we quickly move over to the path
breaking work of Clarke which extends the domain of nonsmooth analysis from convex to locally Lipschitz functions. Clarke
was the second doctoral student of R.T. Rockafellar. We discuss the notions of Clarke directional derivative and the Clarke
generalized gradient and also the relevant calculus rules and applications to optimization. While discussing locally Lipschitz
optimization we also try to blend in the computational aspects of the theory wherever possible. This is followed by a discussion
of the geometry of sets with nonsmooth boundaries. The approach to develop the notion of the normal cone to an arbitrary set
is sequential in nature. This approach does not rely on the standard techniques of convex analysis. The move away from convexity
was pioneered by Mordukhovich and later culminated in the monographVariational Analysis by Rockafellar and Wets. The approach of Mordukhovich relied on a nonconvex separation principle called theextremal principle while that of Rockafellar and Wets relied on various convergence notions developed to suit the needs of optimization. We
then move on to a parallel development in nonsmooth optimization due to Demyanov and Rubinov called Quasidifferentiable optimization.
They study the class of directionally differentiable functions whose directional derivatives can be represented as a difference
of two sublinear functions. On other hand the directional derivative of a convex function and also the Clarke directional
derivatives are sublinear functions of the directions.
Thus it was thought that the most useful generalizations of directional derivatives must be a sublinear function of the directions.
Thus Demyanov and Rubinov made a major conceptual change in nonsmooth optimization. In this section we define the notion of
a quasidifferential which is a pair of convex compact sets. We study some calculus rules and their applications to optimality
conditions. We also study the interesting notion of Demyanov difference between two sets and their applications to optimization.
In the last section of this paper we study some second-order tools used in nonsmooth analysis and try to see their relevance
in optimization. In fact it is important to note that unlike the classical case, the second-order theory of nonsmoothness
is quite complicated in the sense that there are many approaches to it. However we have chosen to describe those approaches
which can be developed from the first order nonsmooth tools discussed here. We shall present three different approaches, highlight
the second order calculus rules and their applications to optimization. 相似文献
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The stress state of the surface layer of a polymeric mass during filling of bulky compression molds is analyzed. It is shown that, at particular rheological characteristics of the mass, temperature, and filling rates, cracking of the surface layer occurs, which leads to defects in the finished products. A physical analysis of this process makes it possible to conclude that the cracks arise due to the normal stresses operating in the front region of the moving polymeric mass. It is found that, under certain flow conditions, areas with a pressure lower than the atmospheric one appear on the surface of the polymer. If the tensile stresses arising in these local regions are higher than the tensile strength of the mass, the continuity of the composition is broken in the direction determined by the greatest rate of the normal deformation. To confirm the reliability of the crack-formation mechanism proposed, the distribution of the pressure and normal stresses over the free surface is calculated based on a numerical method. These calculations show that, by comparing the stress level achieved in the front region with the tensile-strength characteristics of the polymeric composition, it is possible to predict, with a sufficient accuracy, the possibility of crack formation in the surface layer of such a mass under given flow conditions and thus to solve the question on flawless manufacturing of products. 相似文献
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Luigi Ingaliso 《Historia Mathematica》2011,38(2):232-247
The contributions made by the Italian mathematician Mario Pieri (1860-1913) are well known in the field of geometry. Pieri was a member of the School of Peano at the University of Turin. There he became engaged both by the problems of logic and by the philosophical aspects of Peano’s epistemology. This article was motivated by Pieri’s address given at the University of Catania, at the inauguration of the 1906-1907 academic year. My aim is to identify Pieri’s philosophical premises as found in his works and to present them in the general framework of the historical development of the Peano School. 相似文献
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The cut polytope of a graph arises in many fields. Although much is known about facets of the cut polytope of the complete
graph, very little is known for general graphs. The study of Bell inequalities in quantum information science requires knowledge
of the facets of the cut polytope of the complete bipartite graph or, more generally, the complete k-partite graph. Lifting is a central tool to prove certain inequalities are facet inducing for the cut polytope. In this paper
we introduce a lifting operation, named triangular elimination, applicable to the cut polytope of a wide range of graphs.
Triangular elimination is a specific combination of zero-lifting and Fourier–Motzkin elimination using the triangle inequality.
We prove sufficient conditions for the triangular elimination of facet inducing inequalities to be facet inducing. The proof
is based on a variation of the lifting lemma adapted to general graphs. The result can be used to derive facet inducing inequalities
of the cut polytope of various graphs from those of the complete graph. We also investigate the symmetry of facet inducing
inequalities of the cut polytope of the complete bipartite graph derived by triangular elimination.
相似文献