In this study, we consider the General Lot Sizing and Scheduling Problem in single level capacitated environments with sequence dependent item changeovers. Process industries may be regarded as suitable application areas of the problem. The focus on capacity utilization and intensively time consuming changeovers necessitate the integration of lot sizing and sequencing decisions in the production plan. We present a mathematical model which captures the essence of cases in the most generic and realistic setting of the problem. We discuss the impact and validity of some of the assumptions commonly encountered in the related literature. We also represent the problem using an alternative formulation and attempt to enhance the formulations with the use of some additional inequalities. Finally, we develop a heuristic by restricting the number of possible changeovers. Computational results are discussed.

This study is concerned with the inventory routing problem with deterministic, dynamic demand and order-up-to level inventory policy. The problem mainly arises in the supply chain management context. It incorporates simultaneous decision making on inventory management and vehicle routing with the purpose of gaining advantage from coordinated decisions. An integrated mathematical model that represents the features of the problem is presented. Due to the magnitude of the model, lagrangean relaxation solution procedures that identify upper bounds and lower bounds for the problem are developed. Satisfactory computational results are obtained with the solution procedures suggested on the test instances taken from the literature.

This study is on the service models for dynamic scheduling of multi-class make-to-stock systems. An exponential single-server facility processes different types of items one by one and demand arrivals for different item types occur according to independent Poisson processes. Inventories of the items are managed by base-stock policies and backordering is allowed. The objective is to minimize base-stock investments or average inventory holding costs subject to a constraint on the aggregate fill rate, which is a weighted average of the fill rates of the item types. The base-stock controlled policy that maximizes aggregate fill rate is numerically investigated, for both symmetric and asymmetric systems, and is shown to be optimal for minimizing base-stock investments under an aggregate fill rate constraint. Alternative policies are generated by heuristics in order to approximate the policy that maximizes aggregate fill rate and performances of these policies are compared to those of two well-known Longest Queue and First Come First Served policies. Also, optimal policy for the service model to minimize average inventory holding cost subject to an aggregate fill rate constraint is investigated without restricting the attention to only base-stock controlled dynamic scheduling policies. Based on the equivalence relations between this service model and the corresponding cost model, it is observed that the base-stock controlled policy that maximizes aggregate fill rate is almost the same as the solution to the service model and cost model under consideration, especially when backorder penalties are large in the cost model as compared to cost parameters for inventory holding or equivalently when the target fill rate is large in the service model.

In this study, we consider a logistics system, in which a single supplier delivers a product to multiple retailers over a finite time horizon. Supplier decides on the amount to order in each period and services retailers facing deterministic dynamic demand via a fleet of vehicles having limited capacity. Each retailer has specific minimum and maximum levels of inventory in an order-up-to level inventory policy setting. The problem is to simultaneously determine the quantity of product to order to the supplier, retailers to be visited, the quantity of product to be delivered to retailers and routes of vehicles in each period so as to minimize system-wide costs. We present a mathematical formulation for the problem, for which we develop several Lagrangian relaxation based solution procedures providing both upper and lower bounds to the problem. We implement these solution procedures on test instances and present the results. Computational study shows that our solution procedures generate good feasible solutions in reasonable time.

Sustainable competitive advantage (CA) is a necessary requirement of a rational economic business organisation. Without this CA a business does not have a rational source for appropriating added value in the form of retained profit. Various management research papers have identified numerous factors that may create a source of competitive advantage. Other researchers have shown how industries have changed through time. This thesis shows a temporal development of competitive advantage for the construction industry (CAC). The thesis will structure sources of CA to show the significance of each source during the lifecycle of the business and the industry. The thesis shows how the identified sources vary over time. The thesis will develop the concept of a temporal hierarchy as a model for identifying and developing potential sources of CA at any point in the lifecycle of a particular business entity. The research identifies which sources of CA may be most appropriate (at a given point in the lifecycle) to sacrifice in order to create a further (and higher) source of CA. The proposed temporal hierarchy suggests four 'dynamic' epochs, Factor, Investment, Innovation and Wealth and when these epochs are combined with the 'detail' hierarchies of internal 'detail', distinctive capability 'detail' and external 'detail' a comprehensive anatomy of competitive advantage within the construction industry is presented. The conclusion of the thesis includes examples of the application of the temporal model to a small sample of case studies, showing the representativeness of the model to 'real-life' businesses. The phenomenological reservations implicit in the study are evaluated and recommendations are made for further research.

In this study, we focus on pricing and production decisions in reusable container systems with stochastic demand. We consider a producer that sells a single product to the customers in reusable containers with two supply options: (i) brand-new containers, (ii) returned containers from customers. Customers purchasing the products may return the containers to the producer to receive a deposit price. The return quantity depends on both customer demand and the deposit price determined by the producer. Hence, the producer has the opportunity to manipulate the return quantity via the deposit price. The unit cost of filling brand-new containers is different than the unit cost of refilling returned containers. We also consider resource restrictions on the production operations. Our setting represents certain hybrid manufacturing / remanufacturing systems where (i) the producer collects and recovers his own products, (ii) the producer supplies both brand-new and recovered products to his customers, and (iii) the customers are indierent between brand-new and recovered products. In this setting, we investigate the optimal pricing and production decisions in order to maximize the producer`s profit. Our approach utilizes non-linear optimization techniques. We characterize the optimal acquisition fee and the optimal order quantity of brand-new containers analytically and investigate the effect of parameters with an extensive computational study.

Limited asset visibility is a key problem in the management of returnable transport items (RTIs) like reusable containers, pallets and kegs. One tool to increase asset visibility is radio frequency identification (RFID) technology. However, RFID requires high investment cost and intensive efforts for implementation. In this study, we investigate the added value of using RFID technology for the management of the RTI pool in a closed-loop supply chain setting considering both costs and benefits. We have conducted a case study in a company which has recently started an RFID application in its closed-loop supply chain of RTIs. The aim of this case study is to identify and understand how an existing RTI pool is managed and the impact of using RFID technology on the management of such an RTI pool. In order to quantify the added value of RFID technology in RTI pool management, we search for the minimum cost solutions both without and with the use of RFID technology in a problem environment similar to that of our case study using the simulation optimization method. We also analyze the impact of using RFID technology on RTI pool management in terms of several performance measures, including RTI pool size, RTI lifetime, RTI trippage and the cycle time for RTIs to complete one trip in the closed-loop supply chain. In our study, we develop a number of discrete event simulation models of the identified closed-loop supply chain of RTIs operating with our predetermined decision rules for the RTI pool management using the simulation software Arena. We then develop our simulation optimization model in OptQuest for Arena in which the discrete event simulation models are embedded. The results from the simulation optimization method show that the added value of using RFID technology is mostly positive and it depends on the severity of the problematic issues in the closed-loop supply chain, as well as on the extent of improvements that RFID brings about.

El presente trabajo de investigación busca implementar una metodología de diseño de mallas de perforación y voladura en la empresa Minera Sotrami S.A, perteneciente al rubro de pequeña minería, con fines de estandarizarlo. La ejecución de dicha investigación se realiza mediante la utilización del algoritmo matemático de Holmberg que permite definir un modelo numérico para el diseño de una malla de perforación, y con la consideración de criterios operacionales encontrar una malla técnica que permita mejorar los rendimientos en las labores de exploración y desarrollo. Para el logro del mismo, se consideró como variable fija el tipo de roca (tipo III A) y las características geomecánicas presentes en ella; el diámetro del taladro de perforación como variable fija; y, el tipo de explosivo y accesorio de voladura como cambiantes, ya que se reemplazó la utilización de guías, mecha de seguridad y dinamita por el empleo de detonadores no eléctricos (Exaneles) y emulsiones encartuchadas. La oportuna y pertinente estandarización del proceso de perforación y voladura permitió obtener los siguientes resultados: el avance por disparo pasó a 1.62 m, el factor de carga se redujo a 13.46 kg/m y el factor de potencia disminuyo considerablemente. / This research work seeks to implement a design methodology for drilling and blasting meshes in the company Minera Sotrami S.A, belonging to the small mining sector, with finality to standardize it. This research is carried out by using the Holmberg mathematical algorithm that allows defining a numerical model for the design of a drilling mesh, and with the consideration of operational criteria, finding a technical mesh that allow improving the performance of exploration and development labors. To achieve it, the type of rock (type III - A) and the geomechanical characteristics present in it were considered as a fixed variable; the diameter of the drill as a fixed variable; the type blasting attachment and explosives as changeable, since the use of guides, safety wick and dynamite was replaced with the use of non electric detonators (Exaneles) and encapsulated emulsions. The opportune and pertinent standardization of the drilling and blasting process allowed obtaining the following results: the advance per shot was to 1.62 m, the load factor was reduced to 13.46 kg/m and the power factor decreased considerably. / Tesis

By definition, all projects are unique / however R&amp / D projects have specific characteristics that make them harder to manage. The project management methodology applied to R&amp / D projects may show differences due to the categorization of them. But if there exists a categorization of projects, one can analyze the properties of the project classes and then manage similar projects similarly. In this study, the R&amp / D projects of a main military electronics company of Turkey, are analyzed. Tun&ccedil / (2004) has developed a methodology for clustering the projects of this electronics company. Continuing from his studies, a methodology for determining the class of a new project of this electronics company is developed. For defining the projects in a project space, a Project Identification Card (PIC) is developed. The measurement scale of the PIC is constructed by using the absolutemeasurement Analytic Hierarchy Process. A clustering Tabu Search algorithm is generated for using in the sensitivity analyses of the clusters to projects. And a methodology for determining the cluster of a new project is developed.

Thesis (Master of Business Administration) -- Naval Postgraduate School, 2005. / Title from title screen (viewed Aug. 26, 2008). "December 2005." The original document contains color images. "ADA443358"--URL. Includes bibliographical references (p. 85-91). Also issued in paper format.