The design of the distribution system is a strategic issue for almost every company. The problem of locating facilities and allocating customers covers the core topics of distribution system design. Model formulations and solution algorithms which address the issue vary widely in terms of fundamental assumptions, mathematical complexity and computational performance. This paper reviews some of the contributions to the current state-of-the-art. In particular, continuous location models, network location models, mixed-integer programming models, and applications are summarized.

We study some complex distribution network design problems, which involve facility location, warehousing, transportation and inventory decisions. Several realistic scenarios are investigated. Two kinds of mathematical programming formulations are proposed for all the introduced problems, together with a proof of their correctness. Some formulations extend models proposed by Perl and Daskin (1985) for some warehouse location-routing problems; other formulations are based on ow variables and constraints. 1

This paper presents a method for solving the multi-depot location-routing problem (MDLRP). Since several unrealistic assumptions, such as homogeneous #eet type and unlimited number of available vehicles, are typically made concerning this problem, a mathematical formulation is given in which these assumptions are relaxed. Since the inherent complexity of the LRP problem makes it impossible to solve the problem on a larger scale, the original problem is divided into two sub-problems, i.e., the location-allocation problem, and the general vehicle routing problem, respectively. Each sub-problem is then solved in a sequential and iterative manner by the simulated annealing algorithm embedded in the general framework for the problemsolving procedure. Test problems from the literature and newly created problems are used to test the proposed method. The results indicate that this method performs well in terms of the solution quality and run time consumed. In addition, the setting of parameters throughout the solution procedure for obtaining quick and favorable solutions is also suggested. Scope and purpose In many logistic environments managers must make decisions such as location for distribution centers (DC), allocation of customers to each service area, and transportation plans connecting customers. The location-routing problems (LRPs) are, hence, de"ned to "nd the optimal number and locations of the DCs,

Abstract: This paper is a survey of location-routing: a relatively new branch of locational analysis that takes into account vehicle routing aspects. We propose a classification scheme and look at a number of problem variants. Both exact and heuristic algorithms are investigated. Finally, some suggestions for future research are presented.

this paper is posed in the context of a home health care problem. Despite the fact that in this industry, health care is provided by many qualified individuals such as registered nurses, physical therapists and home health aides, for notational simplicity, we will refer to the employees as simply nurses. The only differentiation that we make is between salaried workers (full-time nurses) and non-salaried workers (part-time nurses). Salaried workers are paid for a full-time shift everyday, whether or not they are scheduled to work the entire time. They are paid overtime if they are required to work for longer than the standard shift length. Part-time nurses are paid by the hour. The differences in the nurses' qualifications are represented by a binary relationship with each patient; a nurse-patient pair is thus, either a feasible match or an infeasible match. Accordingly, the nurse may be scheduled to visit the patient, or he or she may not. Additionally, a company in this industry would like to not only satisfy a customer's need for health care, but also keep the customer happy by providing dependable service (i.e. providing health care when the customer requests it). Thus, most home health care companies allow the customer to specify a time window during which he or she will be at home awaiting the requested care. In summary, the problem is to find an optimal schedule such that each nurse that is scheduled to work leaves from his or her home, visits a set of "feasible" patients within their time windows, takes a lunch break within the nurse's lunch time window, and returns home, all within the nurse's time window (which indicates the times during which the nurse is willing to work) and within the known limit on the length of a shift. The optimal schedule minimizes th...

Thanks to my family; my father Robert and my mother Johanna, and my sisters Maryke and Annaleen, for their encouragement, correspondence and visits, and for having me in their thoughts so often. It is their love and support through the years that made this achievement possible. ii

In this paper we examine, how the benefits of Supply Chain Management, as announced by the literature and widely accepted, can simulatively be proven. We first present selected results of a survey conducted on the European automotive industry, which show an evident need for transparency, in terms of the quantification of the added-value of Supply Chain Management. For this purpose we introduce an XML-based prototype for modeling and simulating cooperative scenarios in supply chains, and illustrate its flexible architecture and the interaction between modeled scenarios and optimization routines through XML interfaces. In the context of this prototype we describe a simulation scenario in which the transportation activities in a supply chain are modeled and planned. We then run simulations in a cooperative and in a non-cooperative context and compare the results for the entire supply chain. This comparison can provide information about the benefits of cooperative logistics planning (i.e. Supply Chain Management), which for instance can be realized by implementing Supply Chain Management software for distribution planning purposes.

This paper presents an exact method for two important generalizations of the classical Capacitated Vehicle Routing problem (CVRP): the Period Vehicle Routing Problem (PVRP) and the Multi-Depot Vehicle Routing Problem (MDVRP). The VRP is defined on a graph G=(V, A), where V={0,1,...,n} is the vertex set and A={(i,j): i,jUV, i j} is the arc set. The distinguished vertex 0 represents the depot where m identical vehicles of capacity Q are located. Each vertex iV\{0} corresponds to a customer and has a non negative demand q i . With each arc (i,j) A is associated a cost d ij . The CVRP consists of designing one route for each vehicle such that: (i) each route starts and ends at the depot; (ii) each customer is visited exactly once; (ii) the total demand of the customers visited by a route does not exceed Q and (iv) the total route cost is minimized. The PVRP consists of designing a set of routes for each day of a given planning period of p days. Each customer may require k (say) visits dur...

In this paper we examine, how the benefits of Supply Chain Management, as announced by the literature and widely accepted, can simulatively be proven. We first present selected results of a survey conducted on the European automotive industry, which show an evident need for transparency, in terms of the quantification of the added-value of Supply Chain Management. For this purpose we introduce an XML-based prototype for modeling and simulating cooperative scenarios in supply chains, and illustrate its flexible architecture and the interaction between modeled scenarios and optimization routines through XML interfaces. In the context of this prototype we describe a simulation scenario in which the transportation activities in a supply chain are modeled and planned. We then run simulations in a cooperative and in a non-cooperative context and compare the results for the entire supply chain. This comparison can provide information about the benefits of cooperative logistics planning (i.e. Supply Chain Management), which for instance can be realized by implementing Supply Chain Management software for distribution planning purposes.

any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. Modular and Reconfigurable Robots (MRRs) are those designed to address the increasing demand for flexible and versatile manipulators in manufacturing facilities. The term, modularity, indicates that they are constructed by using a limited number of interchangeable standardized modules which can be assembled in different kinematic configurations. Thereby, a wide variety of specialized robots can be built from a set of standard components. The term, reconfigurability, implies that the robots can be disassembled and rearranged to accommodate different products or tasks rather than being replaced. A set of MRR modules may consist of joints, links, and end-effectors. Different kinematic configurations are achieved by using different joint, link, and end-effector modules and by changing their relative orientation. The number of distinct kinematic configurations, attainable by a set of modules, varies with respect to the size of the module set from several tens to several thousands. Although determining the most suitable configuration for a specific task from