Master of Science / Department of Industrial & Manufacturing Systems Engineering / Jessica L. Heier Stamm / The main goal of public health emergency preparedness efforts is to mitigate the impact of events on the health of the population. However, decision-makers must also remain conscientious of the costs associated with these efforts. Planning is further complicated by uncertainty about the location and volume of demand that will need to be met in an emergency, the speed with which demand must be met, and the potential scarcity of needed items once an emergency occurs. To address these challenges, public health emergency planners often keep inventory stockpiles that are distributed when an event happens. Managing these stockpiles is a difficult task, and inefficient stockpile location and equipment distribution strategies can be costly both in terms of cost and public health impact. This research is motivated by challenges faced by state public health departments in creating stockpile location and equipment distribution strategies. The primary emphasis is on facemasks and respirators used by health workers during an influenza pandemic, but the approach is generalizable to other scenarios. The model proposed here uses a two-stage approach to generate a holistic solution to the problem. The first stage uses a pull distribution strategy to make stockpile location decisions. Additionally, it determines how counties should be assigned to stockpiles to minimize both storage and distribution costs. The second stage adopts a push distribution strategy to determine optimal delivery routes based on the county assignments made in stage one. This stage offers guidance for public health planners who have made location-allocation decisions but who then face a different distribution scenario than what was anticipated in the original planning phase. Recourse methods for managing demand uncertainty are also proposed. A case study of the state of Kansas is conducted using the methods introduced in the thesis. The computational results yield several significant insights into the tradeoffs and costs of various facility location-allocation and vehicle routing decisions: • For the tested range of storage and distribution cost parameters, multiple stockpile locations are preferred over a single location. • In a pull distribution system, storage costs play a greater role in location-allocation decisions than distribution costs. • In the push distribution system, finding an optimal vehicle routing plan is computationally intensive for stockpiles with a large number of assigned counties. • Efficient heuristics perform well to design recourse routing plans when realized demand is greater than expected. • In the event that planners wish to specify routes well in advance, the results of this research suggest adopting a robust routing plan based on higher-than-expected demand levels. This thesis makes three important contributions. The first is an optimization approach that considers multiple distribution strategies. This is especially relevant when stockpiling for an influenza pandemic where stockpiles need to be located significantly before the material is needed, during which time the distribution strategy may change. Second, the case study demonstrates that the proposed methods are applicable to a large-scale problem arising in practice. Finally, this research illustrates for decision-makers the tradeoffs between different stockpile management strategies and between optimal and heuristic methods.

Le secteur humanitaire a fortement évolué ces dernières années. Il est poussé à plus de transparence et doit rendre des comptes aux donateurs. Dans ce contexte, notre étude vise à expliciter, mesurer et améliorer l'une des principales caractéristiques des chaines logistiques humanitaires : leur capacité à répondre rapidement et adéquatement aux changements à court terme. Cette capacité, l'agilité, est fortement influencée par la manière dont le réseau logistique est conçu et dimensionné. Notre seconde problématique consiste donc à assurer un niveau déterminé d'agilité aux chaînes logistiques humanitaires en les aidant à mieux positionner leurs ressources. L'objectif est de montrer que l'on peut obtenir ce niveau de service enmaximisant l'efficience du réseau. Nous avons donc quantifié, en terme de coûts, l'impact de plusieurs décisions stratégiques comme le niveau de service, la proximité des fournisseurs et le degré de centralisation du réseau. / A push for increased professionalism during disaster relief operations has been reinforced over the last decade. The uncertainties humanitarian organisations have to cope with and the vital importance of their success has incited them to develop their ability to respond quickly and adequately to short-term changes. This agility capability is becoming highly prized by the private sector. Starting from a framework of supply chain agility, this thesis analyses humanitarian methods and defines an agility maturity model aiming to measure and improve the agility capability of a supply chain. As agility often depends on the adequate balance between delivery capacity and needs, our second problemstatement aims to design a logistics network that can operate under high levels of uncertainty so that for a given level of service in terms of agility, efficiency is maximized. Our study quantifies the impact on costs of various decisions, such as network design, supply strategy or level of service.

Este trabalho teve como objetivo avaliar a influência do ambiente competitivo na solução de problemas de localização de instalações e desenho da cadeia desenvolvendo um modelo matemático que captasse simultaneamente muitos dos aspectos práticos que impactam no funcionamento da cadeia de suprimentos. A seleção destes aspectos foi baseada nos comentários e sugestões que autores desta linha de pesquisa propuseram para aprofundamento da literatura da área. Foi desenvolvido um modelo de programação linear inteira mista (PLIM) aplicando-o em um problema exemplo para avaliar a hipótese de que a configuração de menor custo da cadeia não necessariamente proporciona maior acessibilidade ao mercado e, em seguida, o mesmo modelo foi aplicado a um problema real, de maior porte, no setor de fertilizantes. / The goal of this study was to evaluate the influence of a competitive environment in solving facility location and network design problems by developing a mathematical model that could capture several of the practical aspects that influence both decisions and operations of the supply chain. The selection of these aspects was based on the comments and suggestions proposed by several authors of this field of the literature. The mathematical program developed is based on mixed integer linear programming (MILP) and is firstly applied on an example problem to evaluate the hypothesis that the chain configuration that provides the lowest cost not necessarily also provides the greatest accessibility to the market. Afterwards, the same optimization model is applied to a larger real problem in the fertilizer industry.

Les problèmes d’optimisation discrète sont pour beaucoup difficiles à résoudre, depar leur nature combinatoire. Citons par exemple les problèmes de programmationlinéaire en nombres entiers. Une approche couramment employée pour les résoudreexactement est l’approche de Séparation et Évaluation Progressive. Une approchedifférente appelée « Resolution Search » a été proposée par Chvátal en 1997 pourrésoudre exactement des problèmes d’optimisation à variables 0-1, mais elle restemal connue et n’a été que peu appliquée depuis.Cette thèse tente de remédier à cela, avec un succès partiel. Une première contributionconsiste en la généralisation de Resolution Search à tout problème d’optimisationdiscrète, tout en introduisant de nouveaux concepts et définitions. Ensuite,afin de confirmer l’intérêt de cette approche, nous avons essayé de l’appliquer enpratique pour résoudre efficacement des problèmes bien connus. Bien que notrerecherche n’ait pas abouti sur ce point, elle nous a amené à de nouvelles méthodespour résoudre exactement les problèmes d’affectation généralisée et de localisationsimple. Après avoir présenté ces méthodes, la thèse conclut avec un bilan et desperspectives sur l’application pratique de Resolution Search. / The combinatorial nature of discrete optimization problems often makes them difficultto solve. Consider for instance integer linear programming problems, which arecommonly solved using a Branch-and-Bound approach. An alternative approach,Resolution Search, was proposed by Chvátal in 1997 for solving 0-1 optimizationproblems, but remains little known to this day and as such has seen few practicalapplications.This thesis attempts to remedy this state of affairs, with partial success. Itsfirst contribution consists in the generalization of Resolution Search to any discreteoptimization problem, while introducing new definitions and concepts. Next, wetried to validate this approach by attempting to solve well-known problems efficientlywith it. Although our research did not succeed in this respect, it lead usto new methods for solving the generalized assignment and uncapacitated facilitylocation problems. After presenting these methods, this thesis concludes with asummary of our attempts at practical application of Resolution Search, along withfurther perspectives on this matter.

Manufacturing outsourcing in the U.S. has never been stronger than it is today. Increased outsourcing has led to significant changes in the design of the retail distribution network. While the traditional distribution network had the manufacturing plants supplying goods to the retail stores directly, the off-shore manufacturing has increased the network's demand for transportation and warehousing to deliver the goods. Thus, most companies have a complex distribution network with several import and regional distribution centers (RDC). In this thesis, we study an integrated facility location and inventory allocation problem for designing a distribution network with multiple national (import) distribution centers (NDC) and retailers. The key decisions are where to locate the RDCs and how much inventory to hold at the different locations such that the total network cost is minimized under a pre-defined operational rule for the distribution of goods. In particular, the inventory cost analysis is based on the continuous review batch ordering policy and the base-stock policy. Both Type-I (probability of stock-outs) and Type-II (fill-rate) service level measures are used in the analysis. Two different models are presented in this thesis for solving the integrated facility location-inventory allocation problem. The first model, continuous approximation (CA), assumes the distribution network to be located in a continuous region and replaces the discrete store locations with a store density function. The second model is a discrete representation of the problem as a mixed integer programming problem. Both the models take a nonlinear form and solution techniques are developed using the theory of nonlinear programming and linear reformulation of nonlinear problems. The goal of the first part of the thesis is to model the problem using a modified CA approach and an iterative solution scheme is presented to solve it. The main contribution of this work lies in developing a refined CA modeling technique when the discrete data cannot be modeled by a continuous function. In addition, the numerical analysis suggests that the total network cost is significantly lower in the case of the integrated model as compared with the non-integrated model. It is also shown that the regular CA approach leads to a solution which is inferior to the solution obtained by the modified CA approach. Our analysis shows that the type of service measure used affects the network design. In the second part of the thesis, the problem is modeled as a nonlinear mixed integer program and a linear reformulation solution technique is proposed to obtain a lower bound on the original problem. Computational results are presented for small problem instances. We conclude this part of the thesis by presenting an integrated model when a base stock inventory policy is used. A drop-decomposition heuristic is proposed to solve this problem.

In this study, a Lagrangean heuristic based on Lagrangean relaxation and subgradient optimization is proposed for the two-stage modular capacitated facility location problem. The objective is to minimize the cost of locating and operating plants and warehouses, plus the cost of transporting goods at both echelons to satisfy the demand of customers. The difference of our study from the two-stage capacitated facility location problem is the existence of multiple capacity levels as a candidate for each plant in the problem. Each capacity level has a minimum production capacity which has to be satisfied to open the relevant capacity level. Obviously, a single capacity level can be selected for an opened facility location. In the second echelon, the warehouses are capacitated and have unique fixed and variable costs for opening and operating. Multiple sourcing is allowed in both transportation echelons. Firstly, we develop a mixed integer linear programming model for the two-stage modular capacitated facility location problem. Then we develop a Lagrangean heuristic to solve the problem efficiently. Our Lagrangean heuristic consists of three main components: Lagrangean relaxation, subgradient optimization and a primal heuristic. Lagrangean relaxation is employed for obtaining the lower bound, subgradient optimization is used for updating the Lagrange multipliers at each iteration, and finally a three-stage primal heuristic is created for generating the upper bound solutions. At the first stage of the upper bound heuristic, global feasibility of the plants and warehouses is inspected and a greedy heuristic is executed, if there is a global infeasibility. At the next stage, an allocation heuristic is used to assign customers to warehouses and warehouses to plants sequentially. At the final stage of the upper bound heuristic, local feasibilities of the plants are investigated and infeasible capacity levels are adjusted if necessary. In order to show the efficiency of the developed heuristic, we have tested our heuristic on 280 problem instances generated randomly but systematically. The results of the experiments show that the developed heuristic is efficient and effective in terms of solution quality and computational effort especially for large instances.

Σχεδόν κάθε επιχείρηση ιδιωτικού και δημόσιου τομέα την οποία μπορούμε να σκεφτούμε, έχει βρεθεί αντιμέτωπη με το πρόβλημα της χωροθέτησης των εγκαταστάσεών της κάποια στιγμή στην ιστορία της. Αυτό έχει οδηγήσει σε ένα έντονο ενδιαφέρον για την ανάλυση χωροθέτησης στα πλαίσια της επιχειρησιακής έρευνας. Η εγκατάσταση ενός νέου τραπεζικού υποκαταστήματος που αποτελεί ένα σημαντικό μέρος του προγραμματισμού και της διαχείρισης δικτύων κλάδων. απαιτεί μία πολύπλοκη διαδικασία λήψης απόφασης. Η λήψης της απόφασης αυτής μπορεί να ωφεληθεί από τη χρήση της πολυκριτηριακής ανάλυσης αποφάσεων (MCDM) καθιστώντας τη διαδικασία πιο ορθολογική και αποδοτική. Στην παρούσα εργασία εξετάζουμε το πρόβλημα της χωροθέτησης ενός τραπεζικού καταστήματος στα πλαίσια της πολυκριτηριακής ανάλυσης αποφάσεων (MCDM). / Almost every private and public sector enterprise that we can think of, has been faced with the problem of locating facilities at one time or another of its history. Τhis has led to a strong interest in location analysis within the operations research and management science community. Locating a new bank branch, an important part of branch network planning and management is a complex decision making progress. This decision making progress can benefit from the use of Multi-Criteria Decision Making (MCDM) progress by making the progress more explicit, rational and efficient. In the present work we examine the problem of locating a bank branch using MCDM.

Σήμερα, ίσως περισσότερο από κάθε άλλη περίοδο στο παρελθόν, η ποιότητα έχει αναδειχθεί ως η ουσιώδης προϋπόθεση επιβίωσης των προϊόντων και των υπηρεσιών. Ο γκουρού της ποιότητας E.W. Deming το 1980 έγραφε: «Στο τέλος του αιώνα θα υπάρχουν δύο είδη επιχειρήσεων. Αυτές που εφαρμόζουν Συστήματα Ολικής Ποιότητας και εκείνες που δεν θα υπάρχουν πλέον στον επιχειρηματικό χώρο». Ο αφορισμός αυτός ίσως ακούγεται υπερβολικός. Το γεγονός όμως ότι ζούμε σε ένα έντονα ανταγωνιστικό και παγκοσμιοποιημένο περιβάλλον, ιδιαίτερα σε μια τέτοια περίοδο οικονομικής κρίσης, κάνει κατανοητό πως το κλειδί για την επιβίωση και την αποτελεσματικότητα των επιχειρήσεων είναι η υψηλή ποιότητα των προϊόντων και των υπηρεσιών που παρέχουν και η σύνδεση τους με την ικανοποίηση του πελάτη. Σκοπός της παρούσας διπλωματικής εργασίας είναι, αφενός, η μελέτη εκείνων των μοντέλων χωροθέτησης που αφορούν την κάλυψη της ζήτησης των προϊόντων / υπηρεσιών και αφετέρου η ενσωμάτωση, σε αυτά, της ποιότητας ως χαρακτηριστικό των εγκαταστάσεων που πρόκειται να χωροθετηθούν. / The purpose of this thesis is to describe the facility location models regarding to the demand covering of products and services and to integrate quality as a characteristic of the facilities.

DIAS, Fábio Carlos Sousa. Algoritmos para o problema de localização simples baseados nas formulações clássica e canônica. 2008. 81 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências, Departamento de Computação, Fortaleza-CE, 2008. / Submitted by guaracy araujo (guaraa3355@gmail.com) on 2016-06-22T17:13:52Z No. of bitstreams: 1 2008_dis_fcsdias.pdf: 533140 bytes, checksum: 547c9cf8d771e2646884c423f5a39936 (MD5) / Approved for entry into archive by guaracy araujo (guaraa3355@gmail.com) on 2016-06-22T17:16:23Z (GMT) No. of bitstreams: 1 2008_dis_fcsdias.pdf: 533140 bytes, checksum: 547c9cf8d771e2646884c423f5a39936 (MD5) / Made available in DSpace on 2016-06-22T17:16:23Z (GMT). No. of bitstreams: 1 2008_dis_fcsdias.pdf: 533140 bytes, checksum: 547c9cf8d771e2646884c423f5a39936 (MD5) Previous issue date: 2008 / In this work, we study the Simple Plant Location Problem (SPLP). Using its classical mathematical programming formulation and another recently proposed formulation, we develop several algorithms to …nd lower and upper bounds for the problem as well as branch-and-bound algorithms. With the classical formulation, such bounds are obtained via the data correction method and dominance criteria between …xed and transportation costs. We propose a projection of this formulation that has shown to be computationally atractive. Using the new formulation, we propose and prove the correctness of several iterative procedures that attempt to …nd an optimal solution to the problem by solving a sequence of parametric sub-problems, each one obtained by removing some variables and constraints of the original formulation. At each iteration of this process, we can obtain lower and upper bounds. We also apply Lagrangean relaxation to this new formulation in order to get other bounds. We consider several possibilities of relaxing the constraints. In addition, we develop branch-and-bound algorithms based on both formulations and the obtained bounds. We evaluate the computational e¢ ciency of all proposed algorithms with hard test instances from the literature. Computational results are reported and comparisons with other algorithms from the literature are carried out. / Neste trabalho, estudamos o problema de localização simples (SPLP - Simple Plant Location Problem). Usando a formulação matemática clássica e uma outra formulação proposta recentemente, desenvolvemos vários algoritmos para encontrar limites inferiores e superiores, bem como algoritmos tipo branch-and-bound. Com a formulação clássica, tais limites são obtidos utilizando o método de correção de dados e critérios de dominância entre os custos …xos e de transporte. Propomos uma projeção dessa formulação, que se mostrou computacionalmente atrativa. Usando a nova formulação propomos e mostramos a corretude de vários procedimentos iterativos que procuram encontrar uma solução para o problema, resolvendo uma seqüência de subproblemas paramétricos obtidos com a remoção de variáveis e restrições da formulação original. Em cada iteração desse processo, podemos gerar limites inferiores e superiores. Aplicamos ainda relaxação lagrangeana a essa nova formulação para obter outros limites. Analisamos várias possibilidades de relaxação das restrições. Desenvolmento também algoritmos branch-and-bound baseados em ambas as formulações e nos limites obtidos. Avaliamos a e…ciência computacional de todos os algoritmos com instâncias de teste difíceis, disponíveis na literatura. Resultados computacionais e comparações com outros algoritmos da literatura são reportados.

abstract: In order to address concerns about the dominance of petroleum-fueled vehicles, the transition to alternative-fueled counterparts is urgently needed. Top barriers preventing the widespread diffusion of alternative-fuel vehicles (AFV) are the limited range and the scarcity of refueling or recharging infrastructures in convenient locations. Researchers have been developing models for optimally locating refueling facilities for range-limited vehicles, and recently a strategy has emerged to cluster refueling stations to encourage consumers to purchase alternative-fuel vehicles by building a critical mass of stations. However, clustering approaches have not yet been developed based on flow-based demand. This study proposes a Threshold Coverage extension to the original Flow Refueling Location Model (FRLM). The new model optimally locates p refueling stations on a network so as to maximize the weighted number of origin zones whose refuelable outbound round trips exceed a given threshold, thus to build critical mass based on flow-based demand on the network. Unlike other clustering approaches, this model can explicitly ensure that flow demands “covered” in the model are refuelable considering the limited driving range of AFVs. Despite not explicitly including local intra-zonal trips, numerical experiments on a statewide highway network proved the effectiveness of the model in clustering stations based on inter-city flow volumes on the network. The model’s policy implementation will provide managerial insights for some key concerns of the industry, such as geographic equity vs. critical mass, from a new perspective. This project will serve as a step to support a more successful public transition to alternative-fuel vehicles. / Dissertation/Thesis / Masters Thesis Geography 2015