多类型乘用车装载方案优化应用研究

为解决整车物流配送中多类型乘用车装载方案制定的效率低下、成本过高等问题,制定各类型轿运车配载方案选择与使用数量优化两阶段的求解思路:第一阶段根据轿运车以及乘用车的尺寸属性,运用排样算法筛选出空间利用率较高的配载方案;第二阶段,将轿运车使用数量转化为配载方案使用次数的总和,在此基础上建立以轿运车使用数量最小为目标的装载方案优化模型,并运用Matlab7.0编程求解.实例验证表明,设计的模型与算法能在更短时间内得到最优解,具有较强的理论及现实意义.     

乘用车物流运输装载模型研究

对乘用车物流运输计划问题进行了研究,首先,建立了以单辆轿运车实载率最大为目标的单车最佳装载方案模型,以该方案配送乘用车辆直到运输任务完成以获得初始轿运车数,其次以空载率最小为目标设计了数量调整模型对初始轿运车数进行优化,得到最优装载方案模型.基于上述优化模型计算最小的轿运车数,建立在轿运车数量限制下的最短行驶里程模型,选择总行驶里程最小的装载方案作为最优的配送方案.最后建立基于路径的物流运输装载模型,运用Floyd算法计算任意起讫点间的最短路径,设计了一种全局搜索算法得到一种合理的配送方案,并以空载率最小为目标对方案进行优化.     

乘用车物流运输计划问题的研究

针对我国汽车工业高速发展的趋势,对乘用车物流运输计划问题进行了数学建模分析.根据实际需求,把问题分为装载问题和运输问题进行分析,本着先装后运的原则,对全部轿运车和乘用车进行配载优化.用两种类型的轿运车,采用整数规划的策略,结合线性规划的理论建立数学模型,并利用lingo软件编程求解,得到最优装载方案.     

复杂电磁环境下兵力部署优化模型

兵力部署通常由任务区分、兵力编组和兵力配置顺序构成.从战场指挥与控制的角度看,以上3个阶段的局部优化并不意味兵力部署的优化,因此有必要建立具有反馈特征和循环机制的全局优化模型.以任务区分、兵力编组、兵力配置和兵力部署之间的逻辑关系为桥梁,以部队应对复杂电磁环境主要措施为控制点,从事件的角度研究"进行兵力部署"事件的最大发生概率,提出了它与"进行任务区分"、"进行兵力编组"和"进行兵力配置"事件发生概率的最优匹配关系.     

基于图论的防空兵力优化配置研究

应用图论将防空系统抽象成二维网络的拓扑结构图,通过指定点对间最小拦截概率的计算,得到防空拓扑图的子图,并应用复杂网络理论,建立了防空节点攻击价值的计算方法.在此基础上设计了防空兵力优化配置算法,给出了能够满足任务要求的兵力配置方案.     

三维多箱异构货物装载优化及其可视化

针对七种现实约束的集装箱三维多箱异构货物装载优化问题,提出了一种基于 “块”和“空间”的启发式搜索算法。算法采用树搜索策略,根据可用空间,对每一次搜索的货物块进行评估,得到最佳的货物块,直到无可用空间或无可装载的货物为止。基于开放式标准测试数据的计算结果表明,该算法在时间效率和体积利用率上均优于已有的同类研究。并基于Net平台开发了一款3D装箱布局优化可视化软件,已在相关物流企业中得到推广应用,验证了算法的实用性。     

带时间窗的三维装载物流配送优化方法研究

针对城市物流配送优化研究在客户服务时间窗和货物装载方式合理结合方面存在的不足,考虑物流配送车厢货物装载方式与客户访问序列相关的特征对车厢空间进行合理的区域划分。首先,构建了包含配送中心的固定成本、配送车辆的运输成本、维修成本、租赁成本和违反时间窗惩罚成本的物流运营成本最小化和配送车辆空间利用率最大化的双目标优化模型;然后,提出一种结合遗传算法(GA)全局搜索能力和禁忌搜索算法(TS)局部搜索能力的GA-TS混合算法求解模型;最后,结合重庆市某配送中心的三维装载物流配送实例数据进行了优化计算,实验结果给出了带时间窗的三维装载物流配送路径优化方案,并进行了不同车厢空间分区模式下平均装载率、物流运营成本和车辆使用数的比较分析。研究表明,当客户需求货物种类数与车辆的空间区域划分数相等且按货物类型进行区域划分时,物流运营成本最小,配送车辆使用数最少和车辆平均装载率最高。     

装载与运输路径的联合最优规划

运输问题中可以分为两个过程:分配装载和规划路径运输,后者是图论问题,前者因为涉及到分配不同的货物装载到不同的运输工具上,是非线性整数规划问题,所以整个问题也是NP复杂问题,随着问题复杂度的增加,变量增多,求解将会非常耗时和困难.提出了基于多旅行商的M-TSP图论装载运输优化模型,和对此模型进行简化后的基于确定路线的整数线性规划装载模型,从而极大的方便此类问题的快速求解,为实际生产运输商业行为提供了一种方便、科学、可靠的决策模型和方案.     

基于启发式算法的乘用车物流运输计划问题研究

主要解决的是乘用车整车物流的运输调度问题,通过对轿运车的空间利用率和运输成本进行优化,建立整数规划模型,设计了启发式算法,求解出了各种运输条件下的详细装载与运输方案.     

货运列车的编组调度问题的研究

对于货运列车的编组调度问题,建立了以压缩中时和增加运量为双目标、多约束的0-1规划模型,采用逐步紧缩中时约束的方法得到了问题一的调度方案.在此基础上对装载特别物资的车辆施加更强的中时约束得到了问题二的调度方案.提出了列车匹配系数的概念并建立了列车最优配对原则,根据该原则对列车进行优化编组得到了问题三的调度方案.基于问题二的数据转换处理得到了问题四的调度方案.     

An efficient sensitivity computation strategy for the evolutionary structural optimization (ESO) of continuum structures subjected to self-weight loads

This work presents a modified version of the evolutionary structural optimization procedure for topology optimization of continuum structures subjected to self-weight forces. Here we present an extension of this procedure to deal with maximum stiffness topology optimization of structures when different combinations of body forces and fixed loads are applied. Body forces depend on the density distribution over the design domain. Therefore, the value and direction of the loading are coupled to the shape of the structure and they change as the material layout of the structure is modified in the course of the optimization process. It will be shown that the traditional calculation of the sensitivity number used in the ESO procedure does not lead to the optimum solution. Therefore, it is necessary to correct the computation of the element sensitivity numbers in order to achieve the optimum design. This paper proposes an original correction factor to compute the sensitivities and enhance the convergence of the algorithm. The procedure has been implemented into a general optimization software and tested in several numerical applications and benchmark examples to illustrate and validate the approach, and satisfactorily applied to the solution of 2D, 3D and shell structures, considering self-weight load conditions. Solutions obtained with this method compare favourably with the results derived using the SIMP interpolation scheme.     

On the multi-component layout design with inertial force

The purpose of this paper is to introduce inertial forces into the proposed integrated layout optimization method designing the multi-component systems. Considering a complex packing system for which several components will be placed in a container of specific shape, the aim of the design procedure is to find the optimal location and orientation of each component, as well as the configuration of the structure that supports and interconnects the components. On the one hand, the Finite-circle Method (FCM) is used to avoid the components overlaps, and also overlaps between components and the design domain boundaries. One the other hand, the optimal material layout of the supporting structure in the design domain is designed by topology optimization. A consistent material interpolation scheme between element stiffness and inertial load is presented to avoid the singularity of localized deformation due to the presence of design dependent inertial loading when the element stiffness and the involved inertial load are weakened with the element material removal. The tested numerical example shows the proposed methods extend the actual concept of topology optimization and are efficient to generate reasonable design patterns.     

An approach for optimization of loading cycles of hydraulic mining excavators

The present paper describes an optimization multi-stage approach for computing the optimal loading cycle of a heavy weight excavator along a predefined trajectory under dynamic constraints such as maximal ensuing forces, accelerations, and maximal allowed hydraulic power. The approach involves the use of splines of 3rd and 5th order for smooth interpolation of the spatial trajectory up to the level of linear and angular accelerations, as well as an SQP optimization routine to find the optimal end-effector motion law along the trajectory, which finally leads to strokes and pressures at the hydraulic actuators as a function of time. The approach can also be extended to other multi-body systems following a predetermined trajectory. The solution scheme can be included in a more general optimization routine aiming to optimize the trajectory itself. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Risk averse elastic shape optimization with parametrized fine scale geometry

Shape optimization of the fine scale geometry of elastic objects is investigated under stochastic loading. Thus, the object geometry is described via parametrized geometric details placed on a regular lattice. Here, in a two dimensional set up we focus on ellipsoidal holes as the fine scale geometric details described by the semiaxes and their orientation. Optimization of a deterministic cost functional as well as stochastic loading with risk neutral and risk averse stochastic cost functionals are discussed. Under the assumption of linear elasticity and quadratic objective functions the computational cost scales linearly in the number of basis loads spanning the possibly large set of all realizations of the stochastic loading. The resulting shape optimization algorithm consists of a finite dimensional, constraint optimization scheme where the cost functional and its gradient are evaluated applying a boundary element method on the fine scale geometry. Various numerical results show the spatial variation of the geometric domain structures and the appearance of strongly anisotropic patterns.     

Modelling the interaction between athlete and sports surfaces

Sports surfaces are often seen as one possible factor for sports injuries as the vertical ground reaction force (VGRF) depends not only on the athlete's movement but also on the mechanical properties of the ground. Therefore, the athlete-surface-interaction has to be analysed in order to minimize the loading on the athlete. The aim of this work is to understand the behaviour during landing and the associated impact forces during ground contact. Thus a simplified mechanical model is presented. Results for feasible surface material parameters are identified. A first assumption of the effect of the VGRF is presented. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Sequential Semidefinite Program for Maximum Robustness Design of Structures under Load Uncertainty

A robust structural optimization scheme as well as an optimization algorithm are presented based on the robustness function. Under the uncertainties of the external forces based on the info-gap model, the maximization of the robustness function is formulated as an optimization problem with infinitely many constraints. By using the quadratic embedding technique of uncertainty and the S-procedure, we reformulate the problem into a nonlinear semidefinite programming problem. A sequential semidefinite programming method is proposed which has a global convergent property. It is shown through numerical examples that optimum designs of various linear elastic structures can be found without difficulty.The authors are grateful to the Associate Editor and two anonymous referees for handling the paper efficiently as well as for helpful comments and suggestions.     

A Symmetric Adaptive Model of Combat

Analytical models are used to examine theories of military combat, a violent conflict between two groups. Typically these models focus on combat power (manpower and technology) and ignore intrinsic sociological factors, both in terms of the interaction between forces, and each force's organizational structure and internal dynamics, such as social climate, morale, and leadership. This paper describes a symmetric adaptive model of combat, in which the use of feedback allows opposing forces to attempt to regulate the intensity of the fight, or even abandon the fight, depending on battlefield losses. Furthermore, parameters are introduced to provide a framework for incorporating the sociological structure and dynamics of the two forces. A preliminary analysis of the model is presented.     

Comparison of analytical and numerical solution for optimal vortex diffuser design

The contribution deals with optimization of wing tip devices, so called vortex diffusers. A comparison is given between an analytical approach for obtaining the optimal circulation loading and the results of a numerical investigation using a lifting line method. The purpose of most wing tip devices is to reduce the induced drag of the main wing by converting vortex energy into thrust. In order to achieve an optimal design, a variational formulation originally proposed by Betz and Prandtl for air screws is applied to the circulation distribution of the diffuser blades. In extension to the inviscid formulation, a viscous correction is applied in order to account for frictional forces. In an effort to validate the analytical results, a comparison is given with numerical solutions from a lifting line method. The loading of the diffuser blades is parametrized and optimized with respect to resulting thrust by use of a quasi-Newton gradient method. Comparison shows that, knowing the velocity distribution in the near wake of the wing, considerable decrease of induced drag may be achieved making use of vortex diffusers. Although actual circulation loading may differ between the analytical and numerical estimation, resulting thrust agrees within a few percent. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

随机网络计划在审计中的应用

审计作为市场经济的自我约束机制,在经济发展中有着不可或缺的责任.本文利用随机网络技术进行分析,旨在设计出高效率的审计活动方案.首先,利用PERT技术建立了确定型的审计活动模型,在此基础上给出了时间—资源优化下的最优人员分配方案;其次,利用GERT技术建立了随机型的审计活动模型,引入矩母函数和梅森公式进行GERT解析求解求出所需的工期等指标,同时采用蒙特卡罗模拟求解验证解析求解的准确性,为审计活动的工期控制提供了理论依据.最后对于工作时间确定的GERT模型,结合PERT和GERT两种技术对其进行简化分析,从而得到了时间—资源优化下的最优人员分配方案.     

The Signorini problem with Coulomb friction for a hyperelastic body under finite deformations

The quasi-static three-dimensional problem of elasticity theory for a hyperelastic body under finite deformations, loading by bulk and surface forces, partial fastening and unilateral contact with a rigid punch and in the presence of time-dependent anisotropic Coulomb friction is considered. The equivalent variational formulation contains a quasi-variational inequality. After time discretization and application of the iteration method, the problem arising with “specified” friction is reduced to a non-convex miniumum functional problem, which is studied by Ball's scheme. The operator in contact stress space is determined. It is shown that a threshold level of the coefficient of friction corresponds to each level of loading, below which there is at least one fixed point of the operator. If the solution at a certain instant of time is known, the iteration process converges to the solution of the problem at the next, fairly close instant of time.