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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

SUPPLY CHAIN SCHEDULING FOR MULTI-MACHINES AND MULTI-CUSTOMERS

2015 September 1900 (has links)
Manufacturing today is no longer a single point of production activity but a chain of activities from the acquisition of raw materials to the delivery of products to customers. This chain is called supply chain. In this chain of activities, a generic pattern is: processing of goods (by manufacturers) and delivery of goods (to customers). This thesis concerns the scheduling operation for this generic supply chain. Two performance measures considered for evaluation of a particular schedule are: time and cost. Time refers to a span of the time that the manufacturer receives the request of goods from the customer to the time that the delivery tool (e.g. vehicle) is back to the manufacturer. Cost refers to the delivery cost only (as the production cost is considered as fi xed). A good schedule is thus with short time and low cost; yet the two may be in conflict. This thesis studies the algorithm for the supply chain scheduling problem to achieve a balanced short time and low cost. Three situations of the supply chain scheduling problem are considered in this thesis: (1) a single machine and multiple customers, (2) multiple machines and a single customer and (3) multiple machines and multiple customers. For each situation, di fferent vehicles characteristics and delivery patterns are considered. Properties of each problem are explored and algorithms are developed, analysed and tested (via simulation). Further, the robustness of the scheduling algorithms under uncertainty and the resilience of the scheduling algorithms under disruptions are also studied. At last a case study, about medical resources supply in an emergency situation, is conducted to illustrate how the developed algorithms can be applied to solve the practical problem. There are both technical merits and broader impacts with this thesis study. First, the problems studied are all new problems with the particular new attributes such as on-line, multiple-customers and multiple-machines, individual customer oriented, and limited capacity of delivery tools. Second, the notion of robustness and resilience to evaluate a scheduling algorithm are to the best of the author's knowledge new and may be open to a new avenue for the evaluation of any scheduling algorithm. In the domain of manufacturing and service provision in general, this thesis has provided an e ffective and effi cient tool for managing the operation of production and delivery in a situation where the demand is released without any prior knowledge (i.e., on-line demand). This situation appears in many manufacturing and service applications.
2

MEDIUM TERM PRODUCTION PLANNING AND CAMPAIGN SCHEDULING FOR SAWMILL

Saadatyar, Sina 07 December 2012 (has links)
In this thesis, we study a multi-period, multi-product, production planning problem for the lumber industry, and present a hierarchical approach to control and schedule lumber production in a sawmill. First, at the sawing unit, the lower level of the hierarchical structure, the combination of log classes, price lists and sawing patterns defines the expected output distribution in terms of lumber pieces. A price list, defining the value of outputs, is fed directly to the sawmill production control optimizer to select the best sawing patterns. This results in a broad variety of different lumber outputs. Second, at the upper level, a mixed integer programming model has been proposed to maximize the total revenue at the sawmill. The lumber outputs determined at the lower level are used as data at the upper level. Market demand, lumber inventory cost, and supply cost are considered over the planning horizon. The proposed model has been developed and implemented on a real-scale prototype sawmill.
3

ON-LINE NETWORK SCHEDULING IN EMERGENCY OPERATION FOR MEDICAL RESOURCES WITH SINGLE-PROCESSOR SINGLE-DESTINATION

2012 November 1900 (has links)
Emergency Management has received more and more attention in the recent years. Most research in this eld focused on evacuation of victims from dangerous places to safe places, but little on allocation of medical resources to safe places and/or transportation tools to the dangerous places. This thesis studies the problem of delivering medical resources from medical centers to the temporary aid site in a disaster-a ected area to help the wounded victims. In particular, this thesis describes a new algorithm for solving this problem. As requirements of medical resources for a disaster a ected area are not known in advance, the problem is in the so-called on-line environment. The algorithm for such a problem is also called on-line algorithm. The evaluation criterion for such an on-line algorithm is the so-called competitive ratio. This thesis considers four cases of such a problem: (1) the capacity of vehicles for transporting medical resources and the number of vehicles are both in nite, (2) the capacity of vehicles is in nite but the number of vehicles is one, (3) the capacity of vehicles is nite and the number of vehicles is in nite, (4) the capacity of vehicles is nite and the number of vehicles is one. Algorithms for the four cases are called H1, H2, H3, and H4, ii respectively. For all these cases, this thesis presents properties, appropriate on-line algorithms and theoretical analysis of these algorithms. The result of the analysis shows that H1 and H3 are optimal based on the competitive ratio criterion while the other two have a very small gap in terms of the optimum criterion. The thesis also presents a case study for having a sense of the performance of H2 and demonstrating practicality of the developed algorithms. The result of this thesis has contributions to the eld of resource planning and scheduling and has application in not only emergency management but also supply chain management in manufacturing and construction.
4

Coordination d'ordonnancement de production et de distribution / Coordination of production and distribution scheduling

Fu, Liangliang 02 December 2014 (has links)
Dans cette thèse, nous étudions trois problèmes d'ordonnancement de la chaîne logistique dans le modèle de production à la demande. Le premier problème est un problème d'ordonnancement de production et de distribution intermédiaire dans une chaîne logistique avec un producteur et un prestataire logistique. Le deuxième problème est un problème d'ordonnancement de production et de distribution aval avec des dates de début au plus tôt et des dates limites de livraison dans une chaîne logistique avec un producteur, un prestataire logistique et un client. Le troisième problème est un problème d'ordonnancement de production et de distribution aval avec des temps de réglage et des fenêtres de temps de livraison dans une chaîne logistique avec un producteur, un prestataire logistique et plusieurs clients. Pour les trois problèmes, nous étudions les problèmes d'ordonnancement individuels et les problèmes d'ordonnancement coordonnés. Nous proposons des algorithmes polynomiaux ou prouvons la NP-Complétude de ces problèmes, et développons des algorithmes exacts ou heuristiques pour résoudre les problèmes NP-Difficiles. Nous proposons des mécanismes de coordination et évaluons le bénéfice de la coordination. / In this dissertation, we aim at investigating three supply chain scheduling problems in the make-To-Order business model. The first problem is a production and interstage distribution scheduling problem in a supply chain with a manufacturer and a third-Party logistics (3PL) provider. The second problem is a production and outbound distribution scheduling problem with release dates and deadlines in a supply chain with a manufacturer, a 3PL provider and a customer. The third problem is a production and outbound distribution scheduling problem with setup times and delivery time windows in a supply chain with a manufacturer, a 3PL provider and several customers. For the three problems, we study their individual scheduling problems and coordinated scheduling problems: we propose polynomial-Time algorithms or prove the intractability of these problems, and develop exact algorithms or heuristics to solve the NP-Hard problems. We establish mechanisms of coordination and evaluate the benefits of coordination.

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