共查询到20条相似文献,搜索用时 109 毫秒
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为了同时解决多行程车辆路径问题和配送中心的定位问题,首先开发了一个以最小化总成本为目标的数学模型,其中总成本包括运输成本和车辆启动成本.然后设计了一个启发式算法解决这个问题,包括三个阶段:第一阶段是找到初始定位并进行路线安排,第二阶段采用模拟退火(SA)的逻辑和交换算法来获得更好的路线,最后阶段是改善由模拟退火算法中当前温度控制的位置.通过标准样例进行的实验结果表明,该算法可以更好地获得一个配送中心定位和有效的相关路线安排.最后,数值实验指出:1)选择不同类型行程的配送方式取决于每辆车的启动成本和单位距离的运输成本;2)使用大容量车辆可以更好地减少运输距离.3)增加服务时间可以有效地减少所需车辆的数量,这三个结果对于多行程车辆路径问题和配送中心的定位问题的管理决策都具有一定的实用价值. 相似文献
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求解车辆路径问题的免疫算法 总被引:1,自引:0,他引:1
将免疫算法用于求解车辆路径问题,并根据车辆路径问题的具体情况提出了一种基于分组匹配的亲和力计算方法.实验结果表明,免疫算法能有效地应用于车辆路径问题. 相似文献
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本文结合汽车零部件第三方物流的实际背景,提出了带时间窗的可分车运输同时收发车辆路径问题(简称SVRPSPDTW),并给出了问题的数学模型,同时提出两个求解该问题的启发式算法,最后进行了数值试验.由于没有可以利用的算例,本文在Solomn测试基准库的基础上构建了针对新问题的算例.计算结果表明,所有算例计算时间均不超过1秒,且算法1无论是从车辆的使用数还是从车辆行驶的路径总长度上都明显优于算法2,从而说明算法1是寻找SVRPSPDTW问题初始可行解的较为有效的算法. 相似文献
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周期性车辆路径问题(PVRP)是标准车辆路径问题(VRP)的扩展,PVRP将配送期由单一配送期延伸到T(T>1)期,因此,PVRP需要优化每个配送期的顾客组合和配送路径。由于PVRP是一个内嵌VRP的问题,其比标准VRP问题更加复杂,难于求解。本文采用蚁群算法对PVRP进行求解,并提出采用两种改进措施——多维信息素的运用和基于扫描法的局部优化方法来提高算法的性能。最后,通过9个经典PVRP算例对该算法进行了数据实验,结果表明本文提出的改进蚁群算法求解PVRP问题是可行有效的,同时也表明两种改进措施可以显著提高算法的性能。 相似文献
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《中学生数学》2017,(20)
<正>In mathematics,you often encounter some difficult problem.When solving math problems,it is often helpful to have an organized problem-solving plan.Today we will talk about"A Plan for Problem Solving"When solving math problems,the four steps listed below can be used to solve any problem.1.Explore·Read the problem carefully.·What facts do you know?·What do you need to find out?·Is enough information given?·Is there extra information?2.Plan·How do the facts relate to each other?·Plan a strategy for solving the problem. 相似文献
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We consider the problem of minimizing the sum of a smooth function and a separable convex function. This problem includes as special cases bound-constrained optimization and smooth optimization with ?1-regularization. We propose a (block) coordinate gradient descent method for solving this class of nonsmooth separable problems. We establish global convergence and, under a local Lipschitzian error bound assumption, linear convergence for this method. The local Lipschitzian error bound holds under assumptions analogous to those for constrained smooth optimization, e.g., the convex function is polyhedral and the smooth function is (nonconvex) quadratic or is the composition of a strongly convex function with a linear mapping. We report numerical experience with solving the ?1-regularization of unconstrained optimization problems from Moré et al. in ACM Trans. Math. Softw. 7, 17–41, 1981 and from the CUTEr set (Gould and Orban in ACM Trans. Math. Softw. 29, 373–394, 2003). Comparison with L-BFGS-B and MINOS, applied to a reformulation of the ?1-regularized problem as a bound-constrained optimization problem, is also reported. 相似文献
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《Numerical Functional Analysis & Optimization》2013,34(7-8):861-884
We investigate the Cauchy problem for linear elliptic operators with C ∞–coefficients at a regular set Ω ? R 2, which is a classical example of an ill-posed problem. The Cauchy data are given at the manifold Γ ? ?Ω and our goal is to reconstruct the trace of the H 1(Ω) solution of an elliptic equation at ?Ω/Γ. The method proposed here composes the segmenting Mann iteration with a fixed point equation associated with the elliptic Cauchy problem. Our algorithm generalizes the iterative method developed by Maz'ya et al., who proposed a method based on solving successive well-posed mixed boundary value problems. We analyze the regularizing and convergence properties both theoretically and numerically. 相似文献
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This paper is a study of certain fully nonlinear 2×2 systems of partial differential equations in one space variable and time. The nonlinearity contains a term proportional to |?U/?x| where U = U(x,t) $isinv; ?2 is the unknown function and |·| is the Euclidean norm on ?2; i.e., a term homogeneous of degree 1 in ?U/?x and singular at the origin. Such equations are motivated by hypoplasticity. The paper introduces a notion of hyperbolicity for such equations and, in the hyperbolic case, proves existence of solutions for two initial value problems admitting similarity solutions: the Riemann problem and the scale-invariant problem. Uniqueness is addressed in a companion paper. 相似文献
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A graph G is dot-critical if contracting any edge decreases the domination number. Nader Jafari Rad (2009) [3] posed the problem: Is it true that a connected k-dot-critical graph G with G′=0? is 2-connected? In this note, we give a family of 1-connected 2k-dot-critical graph with G′=0? and show that this problem has a negative answer. 相似文献
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We shall color the Cartesian product ω × ω1with two colors. Can an infinite subset A ?ω and an uncountable subset B ?ω1 be found such that the product A × B can be one-colored? This problem proves to be unsolvable in ZFC. 相似文献
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Rolando Magnanini 《Applicable analysis》2013,92(2-3):185-192
We study the regularity up to the boundary of solutions to the boundary value problem:[math001] in D, ∣?u∣= g on &;pardD, where D is the unit disc. This problem finds its application in the study of geophysical and geomagnetic surveys. If g?C,[math001](D) and is strictly positive, we prove that uis in the Holder class C1,α(D). An example shows that this is no longer true if g has some zeroes on ?D. In this case u isproved to be of class C1(D) 相似文献
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Benjamin F. Esham 《Mathematical Methods in the Applied Sciences》1990,12(1):77-90
This paper is concerned with the effect of perturbing Burgers' equation by a small term ?2 Utt. It is shown by means of an energy estimate that the solution of Burgers' equation provides a uniform O (?) approximation of the solution of the full hyperbolic problem. Existence and uniqueness of classical solutions for both problems is proved. A related linear problem is first addressed using the Faedo–Galerkin method to obtain key estimates. Important for the hyperbolic problem is the introduction of an ?-dependent energy in order to track the order-? behaviour of various higher-order derivatives. Subsequent use of Schauder technique and Banach contraction mapping principle yields solutions of the semilinear problems. 相似文献
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Rouy Elisabeth 《偏微分方程通讯》2013,38(7-8):1279-1305
We study the following tridimensional magnetostatic inverse shaping problem: can one find a distribution of currents around a levitating liquid metal bubble so that it takes a given shape? It leads to the resolution of an Eilonal equation on the surface of the bubble which has self-contained interest. We answer the question for closed smooth surface which are homeomorphic to a sphere. We give a necessary and sufficient condition on the data for existence and uniqueness of a C1 solution. When the desired shape is axisymmetric and analytic, the solution is also analytic and the problem can be completely solved. A counterexample proves that not all analytic perturbations of such surface are shapable. 相似文献
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W. J. Den Van Broek F. Verhulst W. Eckhaus 《Mathematical Methods in the Applied Sciences》1982,4(1):259-271
The nonlinear potential problem Δ ? = –r2m 0, n = m is studied with r ? 0, n ε (½, ∞), m ε (?1, ∞) and n m > 0. With various additional conditions we have regular and singular solutions which can be studied explicitly by homology transformation. It is proved that if m ? n + 1 = 0 the solution with ?(0) = 1, ≠ (0) = 0 is radiusstable. Numerical analysis of a number of cases with m ? n + 1 = 0 yields the same conclusion. 相似文献