In this dissertation, we consider a multi-item two-echelon inventory distribution system in which the central warehouse operates with (Q, R) policy, and each local warehouse implements base-stock policy. The objective is to find the policy parameters minimizing the relevant system-wide costs subject to an aggregate mean response time constraint at each facility. We first propose an exact solution procedure based on a branch-and-price algorithm to find the relevant policy parameters of the system considered. Then, we propose four alternative heuristics to find the optimal or near-optimal policy parameters of large practical-size systems. The first heuristic, which we call the Lagrangian heuristic, is based on the simultaneous approach and relies on the integration of a column generation method and a greedy algorithm. The other three heuristics are based on the sequential approach, in which first the order quantities are determined using a batch size heuristic, then the reorder levels at the central warehouse and the basestock levels at the local warehouses are determined through the same method used for the Lagrangian heuristic. We also propose a lower bound for the system-wide cost. Later, we extend our study to compound Poisson demand. The performance of the Lagrangian heuristic is found to be extremely well and improves even further as the number of parts increases. Also the computational requirement of the heuristic is quite tolerable. This makes the heuristic very promising for large practical industry-size problems. The performance of the sequential heuristics is also satisfactory, but not as much as the Lagrangian heuristic.

As new information technology (NIT) has become a critical instrument for an organization to gain its competitive edge, the issue of how best to exploit and adopt NIT is now a pressing challenge for organizations and researchers alike. Based on upper echelon theory and individual differences literatures, this research paper endeavors to address the issue concerning the knowledge gap present in previous literature: the correlation between a top manager¡¦s personal traits and his NIT championing behavior. To bridge this gap, this paper attempts to explore to what extent a top manager¡¦s personality, ability, and belief characteristics can affect NIT championing behavior. We venture to propose in this paper a comprehensive model in which top managers¡¦ individual characteristics are integrated to facilitate the analysis of NIT adoption in organization. To test research model, Partial Least Squares (PLS) is used to verify the feasibility of the model proposed. Survey results from 130 top managers in Taiwan strongly support our proposition that a top manager¡¦s personality, ability, and belief have significant influence on NIT championing behavior. At the conclusion section of this paper academic and practical implication is discussed.

Many real-world supply chains can be characterised as large and complex multi-echelon systems since they consist of several stages incorporating assembly and distribution processes. A challenge facing such systems is the efficient management of inventory when demand is uncertain, operating costs and customer service requirements are high. This requires specifying the inventory levels at different stages that minimise the total cost and meet target customer service levels. In order to address this problem, researchers proposed the Stochastic-Service Model and the Guaranteed-Service Model (GSM) approaches. These two approaches differ in terms of assumptions with regard to how to address demand variations and service times. This thesis develops several contributions to the GSM based multi-echelon inventory optimisation problem. First of all, we conduct a comprehensive literature review which gives a synthesis of the various GSM work developed so far. Then, we study the impact of some specific assumptions of the GSM such as bounded demand, guaranteed-service times and common review periods. Our numerical analysis shows that the bounded demand assumption may cause a deviation on customer service levels while the guaranteed-service times and common review periods assumptions may result in an increase on the total cost. In real-world supply chains the impact of these assumptions might be significant. Based on the findings presented while investigating the impact of the common review periods assumption, we develop an extension of the GSM that enables to simultaneously optimise the review periods (reorder intervals) and safety stock levels (order-up-to levels) in general acyclic multi-echelon systems. We formulate this problem as a nonlinear integer programming model. Then, we propose a sequential optimisation procedure that enables to obtain near optimal solutions with reasonable computational time. Finally, we focus on the issue of customer service level deviation in the GSM and propose two approaches in order to mitigate this deviation. The numerical study shows that the first approach outperforms the second one in terms of computational time while the second approach provides more accurate solutions in terms of cost. We also present some related issues in decentralised supply chain settings.

Optimizing supply chain is the most successful key for manufacturing systems to be competitive. Supply chain (SC) has gotten intensive research works at all levels: strategic, tactical, and operational levels. These levels, in some researches, have integrated with each other or integrated with other planning issues such as inventory. Optimizing inventory location and level of safety stock at all supply chain partners is essential in high competitive markets to manage uncertain demand and service level. Many works have been developed to optimize the location of safety stock along supply chain, which is important for fast response to fluctuation in demand. However, most of these studies focus on the design stage of a supply chain. Because demand at different horizon times may vary according to different reasons such as the entry of different competitors on market or seasonal demand, safety stock should be optimized accordingly. At the planning (tactical) level, safety stock can be controlled according to each planning horizon to satisfy customer demand at lower cost instead of being fixed by a decision taken at the strategic level. On the other hand, most studies that consider safety stock optimization are tied to a specific system structure such as serial, assembly, or distribution structure. This research focuses on formulating two different models. First, a multi- echelon safety stock optimization (MESSO) model for general supply chain topology is formulated. Then, it is converted into a robust form (RMESSO) which considers all possible fluctuation in demand and gives a solution that is valid under any circumstances. Second, the safety stock optimization model is integrated with tactical supply chain planning (SCP) for manufacturing systems. The integrated model is a multi-objective mixed integer non-linear programming (MINLP) model. This model aims to minimize the total cost and total time. A case study for each model is provided and the numerical results are analyzed.

In this study, inventory&ndash / distribution system of a company operating in Fast Moving Consumer Goods (FMCG) industry is analyzed. The system is a multi&ndash / item, two-echelon, divergent inventory&ndash / distribution system with transportation constraints. The warehouses in the system are nonidentical and all of the warehouses are allowed to hold stock. The goal is to achive target customer service levels. Throughout the system, inventory is controlled by echelon stock periodic review (R, S) order-up-to level policy. The problem is the determination of inventory control parameters in the system and effective replenishment of the inventories of many items at regional warehouses under transportation constraints. An approach consisting of three modules operating in a hierarchy is developed to manage the system. The approach calculates the inventory control parameters of the items (order-up-to levels at the regional warehouses and stock allocation fractions) / determines the replenishment periods of the items with the objective of balancing the vehicle requirements among periods and performs the daily replenishment of inventories minimizing the maximum deviation from the inventory policy under transportation constraints. A heuristic approach is adapted from the literature for the inventory control parameter determination part of the approach / an IP model is formulated for the replenishment period scheduling part and a MIP model is constructed for the replenishment process. The proposed approach is simulated with retrospective data of the company and compared with the existing system in the company, in terms of the performance measures defined. Satisfactory results are obtained with the proposed system.

De nombreuses chaînes logistiques peuvent être caractérisées comme de larges systèmes multi-échelons, car ils se composent souvent de plusieurs étages qui intègrent des activités d'assemblage et de distribution. L’un des enjeux majeurs associé au management de ces systèmes multi-échelons est la gestion efficace de stocks surtout dans des environnements où la demande est incertaine, les coûts de stocks sont importants et les exigences en termes de niveau de service client sont élevées. Cela nécessite en particulier de spécifier les niveaux de stocks aux différents étages afin de minimiser le coût total du système global et de satisfaire les niveaux cibles de service client. Pour faire face à ce problème, deux approches existent dans la littérature; il s’agit du Modèle de Service Stochastique (SSM) et le Modèle de Service Garanti (GSM). Ces deux approches diffèrent en termes d'hypothèses utilisées concernant la façon de gérer les variations de la demande et les temps de service. Cette thèse amène plusieurs contributions au problème d'optimisation de stocks multi-échelons basé sur le GSM. Tout d'abord, nous menons une revue de la littérature internationale qui donne une synthèse des différents travaux réalisés à ce jour. Ensuite, nous étudions l'impact de certaines hypothèses spécifiques du GSM comme la demande bornée, les temps de service garanti et les périodes d’approvisionnement communes. Notre analyse numérique montre que l'hypothèse de demande bornée peut causer une déviation sur les niveaux de service client tandis que les hypothèses de temps de service garanti et de périodes d’approvisionnement communes peuvent entraîner une augmentation du coût total. En pratique, l’impact de ces hypothèses peut être important. En se basant sur les résultats présentés lors de l'analyse de l’hypothèse des périodes d'approvisionnement communes, nous développons une extension du GSM qui permet d'optimiser simultanément les périodes d’approvisionnement (les intervalles de réapprovisionnement) et les niveaux de stocks de sécurité (les niveaux de recomplétement) dans les systèmes multi-échelons acycliques généraux. Nous formulons ce problème comme un modèle de programmation non-linaire en nombres entiers. Ensuite, nous proposons une procédure d'optimisation séquentielle qui permet d'obtenir des solutions proches de l’optimal avec un temps de calcul raisonnable. Enfin, nous nous concentrons sur le problème de déviation de niveau de service client dans le GSM et nous proposons deux approches afin d'atténuer cette déviation. L'étude numérique montre que la première approche est plus performante que la deuxième en termes de temps de calcul tandis que la deuxième approche offre des meilleures solutions en termes de coût. Nous présentons également des problèmes similaires dans les chaînes logistiques décentralisées. / Many real-world supply chains can be characterised as large and complex multi-echelon systems since they consist of several stages incorporating assembly and distribution processes. A challenge facing such systems is the efficient management of inventory when demand is uncertain, operating costs and customer service requirements are high. This requires specifying the inventory levels at different stages that minimise the total cost and meet target customer service levels. In order to address this problem, researchers proposed the Stochastic-Service Model and the Guaranteed-Service Model (GSM) approaches. These two approaches differ in terms of assumptions with regard to how to address demand variations and service times. This thesis develops several contributions to the GSM based multi-echelon inventory optimisation problem. First of all, we conduct a comprehensive literature review which gives a synthesis of the various GSM work developed so far. Then, we study the impact of some specific assumptions of the GSM such as bounded demand, guaranteed-service times and common review periods. Our numerical analysis shows that the bounded demand assumption may cause a deviation on customer service levels while the guaranteed-service times and common review periods assumptions may result in an increase on the total cost. In real-world supply chains the impact of these assumptions might be significant. Based on the findings presented while investigating the impact of the common review periods assumption, we develop an extension of the GSM that enables to simultaneously optimise the review periods (reorder intervals) and safety stock levels (order-up-to levels) in general acyclic multi-echelon systems. We formulate this problem as a nonlinear integer programming model. Then, we propose a sequential optimisation procedure that enables to obtain near optimal solutions with reasonable computational time. Finally, we focus on the issue of customer service level deviation in the GSM and propose two approaches in order to mitigate this deviation. The numerical study shows that the first approach outperforms the second one in terms of computational time while the second approach provides more accurate solutions in terms of cost. We also present some related issues in decentralised supply chain settings.

Styrelsen är ett bolags främsta styrorgan med ansvar för flera strategiska funktioner, såsom övervakning, disciplinering och finansiering, med målet att säkerställa att företagsledningen agerar i enlighet med bolagets vision och aktieägarnas avkastningskrav. Omfattande kapitalstrukturbeslut kan kräva styrelsens godkännande innan de förverkligas. Detta kan innefatta valet om bolaget ska använda sig av interna eller externa finansieringskällor, vilket påverkar kapitalstrukturen/skuldsättningsgraden.   Tidigare studier har bl.a. undersökt hur styrelsesammansättning påverkat bolagets kapitalstruktur. Studier har påvisat att styrelsestorlek, styrelsens oberoende, medelålder och kön påverkar kapitalstrukturen, där studierna har utgått från pecking-order och trade-off teorierna Traditionellt har bolagsstyrelser återspeglat sig av en homogen sammansättning, avseende variabler som ålder, kön, etnicitet, vilket bidragit till eniga affärsbeslut. Studier som undersökt utbildning, erfarenheter och expertis (humankapital) bland styrelsemedlemmar har fokuserat på bolagets finansiella prestation och innovationsförmåga. Dock finns det ingen studie tagit hänsyn till humankapitalets påverkan på kapitalstrukturen.   Syftet med studien är att analysera styrelsemedlemmars humankapital och deras påverkan på bolagets kapitalstruktur för bolag listade på svenska börsen. Genom att använda en deduktiv ansats och kvantitativa data är målet att få svar på syftet. Teorier om kapitalstruktur, såsom pecking-order och trade-off, samt teorier om styrelsens egenskaper, upper echelon och resursberoendeteorin har använts. Därtill har hypoteser formulerats, där kvantitativa data inhämtats från årsredovisningar och empiriskt operationaliserats.   Resultatet och slutsatsen av studien är att humankapital hos styrelsen har en påverkan på hur kapitalstrukturen ser ut bland bolagen. Studiens resultat påvisade att humankapitalet bland börsbolagen kan påverka kapitalstruktur både positivt och negativt. Slutsatsen är att humankapitalet i bolagsstyrelser följer trade-off teorin gällande finansieringsvalen, d.v.s. styrelsemedlemmar balanserar för - och nackdelar för att nå en optimal kapitalstruktur.

Risk is something intrinsic to business, and something firms are exposed to on a daily basis. This means that there exists a great deal of pressure on the Top Management of a firm to successfully navigate the different risks to which they are exposed. The CEO holds a unique position in the firm, as she is ultimately responsible for deciding which strategies to employ in order to properly respond to these risks. But what influenced the CEO when making such decisions? The Upper Echelon Theory suggests that decisions made by the Top Management Team of a firm are influenced by their values and their cognitive base, which is formed throughout their upbringing. Researchers on Upper Echelon Theory suggest that these two abstract constructs can be difficult to measure and analyse, and should therefore be approximated using specific and observable characteristics of the Top Management Team. In our study, this theory has applied to Swedish CEOs as they are the ultimate decision-maker in a firm. The specific characteristics observed and analysed in our investigation into the relationship between the CEO and risk are; gender, age, nationality, and tenure. Thus, the purpose of this study is formulated as follows: “The purpose of this study is to investigate the relationship between CEO characteristics, specifically age, gender, tenure, and nationality, and firm risk-taking, as measured by the leverage ratio, stock return volatility, cash holdings, and R&D expenditure, on the Swedish market. As a sub-purpose, we intend to investigate whether there is a nonlinear relationship between CEO tenure and risk-taking.” By collecting data from the databases, Thomson Reuters Eikon and Amadeus, a dataset of 284 firms and their CEOs was collected and used in the cross-sectional analysis. Multiple linear regression analysis was employed to determine the relationships between the previously mentioned CEO characteristics and the proxies for firm risk-taking. The majority of the relationships found were of a non-significant nature, indicating that the relationship between Swedish CEO characteristics and the strategies they employ when running their firms is weak and differs from relationships found in earlier studies, using data from different markets. The significant relationships found were between cash holdings and age, long tenures and leverage ratio, and short tenures and stock return volatility. This indicates that older CEOs are more risk-averse, while longer seated CEOs maintain less debt, and shorter seated CEOs are perceived as more risky by the market. However, as these results only entail 15% of our observed results, none of the hypotheses constructed for this study were verified. Therefore, our conclusion is that the previously observed relationships between the characteristics of CEOs and their risk-taking is not present within our sample of firms listed on the Swedish market. Some tendencies that align with previous results have been found but are not generalisable and as a result, we cannot recommend that private actors act on these results.

abstract: A semiconductor supply chain modeling and simulation platform using Linear Program (LP) optimization and parallel Discrete Event System Specification (DEVS) process models has been developed in a joint effort by ASU and Intel Corporation. A Knowledge Interchange Broker (KIBDEVS/LP) was developed to broker information synchronously between the DEVS and LP models. Recently a single-echelon heuristic Inventory Strategy Module (ISM) was added to correct for forecast bias in customer demand data using different smoothing techniques. The optimization model could then use information provided by the forecast model to make better decisions for the process model. The composition of ISM with LP and DEVS models resulted in the first realization of what is now called the Optimization Simulation Forecast (OSF) platform. It could handle a single echelon supply chain system consisting of single hubs and single products In this thesis, this single-echelon simulation platform is extended to handle multiple echelons with multiple inventory elements handling multiple products. The main aspect for the multi-echelon OSF platform was to extend the KIBDEVS/LP such that ISM interactions with the LP and DEVS models could also be supported. To achieve this, a new, scalable XML schema for the KIB has been developed. The XML schema has also resulted in strengthening the KIB execution engine design. A sequential scheme controls the executions of the DEVS-Suite simulator, CPLEX optimizer, and ISM engine. To use the ISM for multiple echelons, it is extended to compute forecast customer demands and safety stocks over multiple hubs and products. Basic examples for semiconductor manufacturing spanning single and two echelon supply chain systems have been developed and analyzed. Experiments using perfect data were conducted to show the correctness of the OSF platform design and implementation. Simple, but realistic experiments have also been conducted. They highlight the kinds of supply chain dynamics that can be evaluated using discrete event process simulation, linear programming optimization, and heuristics forecasting models. / Dissertation/Thesis / M.S. Computer Science 2012

abstract: Over the past several decades, social network remains the most prevalent and prominent in the strategy and organization theory literature. However, despite the considerable research attention scholars devoted to exploring the implications and mechanisms of social ties and networks in management and organizational contexts, the following question has largely remained understudied: To what extent can top managers' personal ties and networks actually contribute to their firms? This thesis will strive to explore this research question by theoretically highlighting three logically consequent managerial decisions: (1) "When"--when will top managers choose to use their personal ties and networks in their firms; (2) "How"--will top managers use their managerial ties and networks to serve the best interest of their firms or to satisfy their self-interests; and (3) "So what" --how would the decision of using managerial ties and networks to benefit their firms influence other decisions of the firms. Using both primary data and archival information from Chinese firms, I will empirically test the step-wise framework. I expect this thesis to contribute to both strategic leadership and social network research and management practices. / Dissertation/Thesis / Doctoral Dissertation Business Administration 2014