Thesis (Ph.D.)--York University, 2008. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 110-135). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR51707

Thesis (M.A.)--Rowan University, 2005. / Typescript. Includes bibliographical references.

Thesis (M.B.A.)--Boston University

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / This research project proposes a supply management model in a consumer goods company in Lima, Peru, to improve stock control and avoid raw materials stockouts and overstock. A Kraljic matrix was used to identify products based on their criticality considering material segmentation, warehouse capacity and times, and ABC segmentation to classify products on each quadrant of the matrix. This project also focuses on defining purchasing and supply strategies in each quadrant of the matrix. This model involves the development of three processes that are related to a new purchasing strategy: economic order quantity, lot-for-lot ordering, and just in time. This new system is based on a more accurate inventory because continuous improvement attracts employees’ attention and engages them in reducing the number of manual notifications made by operators every month. Moreover, after implementing the new procedure for recording inventories, the inventory record was 87% accurate, whereas, in the past, the inventory was not counted and was performed by employees of other areas.

En la presente investigación se sustenta una propuesta de implementación de un modelo de gestión de inventarios, aplicado a una empresa dedicada a la distribución eléctrica en una de las más importantes ciudades del sur del Perú. Los principales objetivos son: Reducir los costos originados debido al sobre stock de inventario, reducir el riesgo de roturas de stock con la consecuente imposición de penalizaciones por parte del ente regulador y adicionalmente establecer un procedimiento para la disposición final de los materiales obsoletos y deteriorados que resultan de la operación de la empresa. / This research supports a proposal for the implementation of an inventory management model, applied to a company dedicated to electricity distribution in one of the most important cities in southern Peru. The main objectives are: To reduce the costs originated due to the stock of inventory, reduce the risk of stock breakage with the consequent imposition of penalties by the regulatory entity and additionally establish a procedure for the final disposal of obsolete and deteriorated materials that they result from the operation of the company. / Tesis

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In this research, we consider the spares provisioning problem, where a finite population of homogeneous machines are being deployed to meet a constant demand. While a machine is operating, it could become inoperable due to the failure of a critical built-in part in the machine. Before repairs on the machine can be initiated, however, a replacement part must be obtained. If a replacement part is available from stock, the machine is immediately transferred to the repair subsystem, in which one or more repair stations operate in parallel. If the replacement part is not in stock, then the machine waits in the ordering subsystem for the arrival of a new part. Once a machine is repaired, it is immediately deployed to meet demand if needed, else it joins a queue of standby machines. The spare machines have zero probability of failure and, if available, a spare replaces a deployed machine immediately upon the latter's failure. The machine operating time, repair time, and ordering time of the parts are assumed to be exponentially distributed. The ordering subsystem for the parts brings a new aspect to the spares provisioning problem, and dramatically increases its difficulty. This is because the queuing network model which describes the system is a non-product-form network in the case of finite nonzero stocking policy, and specification of closed-form solutions is highly unlikely for such networks. In this dissertation, we present efficient algorithms through which the optimal number of machines, repair stations and stocking level of the parts that minimize total operations costs subject to a service-level constraint can be obtained. The algorithms, which based on Little's result from queuing theory and some approximate models used for bounding, have proven to be extremely efficient in terms of computer storage and execution time, even for large problems. / Ph. D.

Master of Science / Department of Industrial & Manufacturing Systems Engineering / John R. English / Inventory accuracy is critical for almost all industrial environments such as distribution, warehousing, and retail. It is quite common for companies with exceptional inventory accuracy to use a technique called cycle counting. For many organizations, the time and resources to complete cycle counting are limited or not available. In this work, we promote statistical process control (SPC) to monitor inventory accuracy. Specifically, we model the complex underlying environments with mixture distributions to demonstrate sampling from a mixed but stationary process. For our particular application, we concern ourselves with data that result from inventory adjustments at the stock keeping unit (SKU) level when a given SKU is found to be inaccurate. We provide estimates of both the Type I and Type II errors when a classic c chart is used. In these estimations, we use both analytical as well as simulation results, and the findings demonstrate the environments that might be conducive for SPC approaches.

published_or_final_version / Statistics / Master / Master of Philosophy