Mathematical analysis of emergency ambulance location

Proper ambulance location is crucial in saving lives and reducing injury. To determine efficient and effective locations, it is necessary to evaluate both the spatial and temporal distributions of demand. Because of the complex nature of the ambulance response and transport activities, the problem is subdivided into a facility location problem and a vehicle allocation problem. A set covering model is modified to solve the location problem while a simulation is used to solve the allocation problem. Combining these two models provides a powerful methodology for systematically finding a satisfactory solution to the ambulance location problem.     

Two-stage optimal control problems and optimality conditions

When an optimal investment decision is studied for a firm whose capital goods are subject to a delivery lag, a control problem with a time-delay argument in the objective function emerges. Such a problem under a set of simple assumptions is shown to be reducible to a two-stage optimal control problem. The significance of this is that familiar tools from standard optimal control theory are applicable to the resulting two-stage problem. Necessary conditions are presented for a general two-stage problem with an adjustable switching time. Some specific results are also obtained for several special cases.     

多式联运环境下带时间窗的多产品运输问题研究

多式联运环境下带时间窗的路径选择问题是广泛应用于物流配送领域的一类组合优化问题,然而目前相关研究主要聚焦于多式联运环境下单个起点到单个终点的一种货物配送问题,其研究成果难以直接适用于汽车销售、钢铁运输等环境下单个供货商到多个零售商的多产品运输问题。因此,文中以汽车销售为研究背景,对多式联运环境下带时间窗的多产品运输问题进行研究,建立了该问题的数学模型,然后利用蚁群算法进行了求解,最后通过实验验证了算法的有效性。     

Decision-making in the supply chain: Examining problem solving approaches and information availability

In this paper we investigate the role of two types of problem solving approaches on supply chain performance. Additionally, we investigate how the level of information availability moderates problem solving approach on supply chain performance. We draw on construal level theory from the experimental psychology literature to explain how the problem solving approaches (abstract problem solving approach vs. concrete problem solving approach) contribute to supply chain performance. From this foundation, we run a series of behavioral experiments to test our hypotheses that problem solving approaches and information availability impact supply chain performance as presented in the beer distribution game. A key finding of this study is that individuals who take an abstract problem solving approach are able to perform better than individuals who take a concrete problem solving approach in the context of limited information availability. However, in the context of complete information availability, the impact of both types of problem solving approaches on performance becomes negligible.     

多旅行商问题研究综述

多旅行商问题是经典旅行商问题的一种泛化,加上某些特定的附加条件,则能够演化成一些较现实的问题,因而具有较高的理论研究和应用价值。在多旅行商问题中,一个任务由多位旅行商共同完成,其问题的求解难度较经典旅行商问题更大,用于经典旅行商问题求解的方法或策略不能简单地应用于多旅行商问题的求解,有关该问题的研究成果远比经典旅行商问题少,本文针对目前有关多旅行商问题的研究进展情况进行综述。     

解决中小企业融资难问题的新视角——融资租赁

中小企业融资难既是一个世界性难题,也是一个长期性问题,解决中小企业融资难的问题,必须不断增加融资渠道,创新融资方式。融资租赁作为一种"融资与融物"一体化的方式,具有其自身的优势,是解决中小企业融资问题的一个有效方式。     

Burn-in for a time-transformed exponential model

The problem of the optimal duration of a burn-in experiment is considered in the case of simultaneous testing n components with the conditionally independent time-transformed exponential life-times, given an unknown parameter. The explicit solution is derived by reformulation of the problem considered to an optimal stopping problem for a suitable defined three-dimensional Markov process and reduction to a free-boundary problem.     

基于遗传算法的高校排课

课表问题又称为时间表问题(Timetable Problem),是一个多因素的优化决策问题,也是组合规划中的典型问题。本文从排课系统研发和运行中存在的问题出发,从遗传算法的基本理论入手,研究如何利用遗传算法,解决时间安排过程中的资源冲突(主要是教师资源和时间资源)、课表时间段组合优化等问题。     

流程网络图主关键路径确定的MATLAB方法

利用工作流网络图的关键路线为耗期最长的特点，将其转化成最短路径问题，然后利用求最短路径的matlab程序，简单方便地求出流程网络图中的主关键路径。     

Thinning and harvesting in stochastic forest models

This paper analyzes a stochastic forest growth model in which the manager is able to first thin the forest to promote better growth before harvesting. Both Wicksell single thinning and harvesting cycle and Faustmann on-going rotation problems are considered. The Wicksell problem is analyzed by first restricting the class of decision times to (thinning, harvesting) pairs that bound the growth away from infinity and imbedding the problem in an infinite-dimensional linear program on a space of triplets of measures. These measures capture the thinning and harvesting decisions along with the behavior of the growth process prior to harvest. An auxiliary linear program then leads to a nonlinear optimization problem for which an optimal value and solution are determined. The values of all the problems are be related through a set of inequalities. The solution of the nonlinear problem determines (random) thinning and harvesting times for the single thinning and harvesting cycle which demonstrate the equality of the values of these various problems. Finally for the Wicksell problem, the unrestricted class of thinning and harvest times is shown to give the same value as the restricted class. The Faustmann on-going thinning and harvesting rotation problem is reduced to a Wicksell problem which then allows for the characterization of the value as the solution to a different nonlinear optimization problem. The effects of the opportunity to thin the forest are illustrated on a mean-reverting stochastic model.     

Symmetric equilibrium strategies in game theoretic real option models

This paper considers the problem of investment timing under uncertainty in a duopoly framework. When both firms want to be the first investor a coordination problem arises. Here, a method is proposed to deal with this coordination problem, involving the use of symmetric mixed strategies.     

制造业的车间调度问题优化算法比较研究

目前,制造业的竞争日益激烈,在企业的日常运作过程中,会经常遇到各种各样的复杂的调度问题,车间生产调度问题解决的好坏直接影响着企业的运作效率和最终的客户满意程度,最终影响着企业对市场的反应能力和竞争力。因此,调度问题已经成为运营管理领域的一大研究热点。大量的学者研究生产调度优化问题,采用了各种优化方法。文章综述了车间生产调度问题的各种优化方法,对其发展历程、优缺点、适用性等都作了详细的说明,并对它们作以比较分析,从而找到最适合现实状况的优化方法。     

A new look at static spatial price equilibrium models

In this paper we propose a new view and more general formulations of static single commodity spatial equilibrium models, that lead to simpler and more efficient algorithms than those previously employed for solving models of this type. The proposed formulations incorporate general transportation networks and may be extended to allow for multiple commodities. Solution algorithms are suggested for the problem with multiple commodities, when there exists an equivalent optimization problem. We show that the multiple commodity problem may be cast in the form of a variational inequality, when there does not exist an equivalent optimization problem and propose algorithms to solve this version of the problem as well.     

战时装备保障的多目标运输问题及其求解

提出了集中考虑时间性，安全性的战时装备保障的多目标运输问题并建立了该运输问题的数学模型。基于一种二次抛物偏大型分布的模糊规划算法，将多目标运输问题转化为单目标运输问题，并通过一种改进的表上作业法求得最做优折衷解。最后给出一个实例， 验证了方法的有效性。     

浅析中国的就业政策

就业问题是关系到国计民生,社会稳定的大问题。近年来,我国的就业问题备受关注。在当今社会复杂多变的形势下如何解决人民就业难的问题一直是许多专家学者研究探讨的热点问题,而分析我国的就业政策,对于我国就业政策的研究有利于解决就业难的问题。     

完善住房保障体系努力实现住有所居

住房问题是民生问题、社会问题,也是经济问题、政治问题.进一步扩大保障性住房建设规模尤为重要.2004年以来,赣州抓好建设、分配、管理环节,构建了以廉租住房实物配租为主,经济适用房、棚户区(危旧房)改造、公共租赁房和廉租店铺等多种形式为补充的具有赣州特色的住房保障体系,较好地解决了中低收入居民住房困难问题.     

On the assignment of students to topics: A Variable Neighborhood Search approach

This article presents a study of a practical assignment problem found in teaching within higher education. Here, students are assigned to scientific topics for which written papers must be submitted. Often, preferences across topics exist among other side constraints that should be considered in solving the problem of interest. Characterizing attributes of real-world problems were studied for scientific departments in Economics and Business Administration at German universities by sending out 800 questionnaires, and analyzing the 203 responses.Based on earlier studies, a Variable Neighborhood Search (VNS) approach was formulated to solve the resulting assignment problem. Several neighborhood search operators were tested, and numerical results are reported for a range of problem scenarios taken from real-world cases. It was observed that VNS leads to superior results vs. single operator local search approaches. Furthermore, we were able to show that in the studied problem, the effectiveness of certain neighborhoods was, to a large extent, dependent on the structures of the underlying problem.An extension of the problem was formulated by integrating a second objective function, which simultaneously balances the workload of staff members while maximizing student utility. The VNS approach was implemented in a computer system, available free of charge, providing decision support for selected other institutions within higher education.     

遗传算法在现代物流系统中的应用研究

遗传算法是一种基于自然进化原理的全局搜索随机算法。通过遗传算法特点的介绍,阐述了物流规划中的相关问题。研究了遗传算法在选址问题、配送问题、调度问题、运输问题、布局问题等问题中的应用方法,介绍了其理论价值,及对实际工作的指导作用。     

Relative efficiency and deficiency of kernel type estimators of smooth distribution functions

Abstract  The problem is investigated whether a given kernel type estimator of a distribution function at a single point has asymptotically better performance than the empirical estimator. A representation of the relative deficiency of the empirical distribution function with respect to a kernel type estimator is established which gives a complete solution to this problem. The problem of finding optimal kernels is studied in detail.     

预算限制约束的竞争分销终端选址问题研究

站在生产厂商的角度,以市场份额最大化为切入点,研究了在零售引力法则的基础上带预算费用限制的竞争型分销终端网点选址问题并建立了模型。讨论说明了该问题是NP-hard问题,并运用Max-Min蚂蚁算法来解决该问题。