Modeling Industrial Lot Sizing Problems: A Review

In this paper we give an overview of recent developments in the field of modeling single-level dynamic lot sizing problems. The focus of this paper is on the modeling various industrial extensions and not on the solution approaches. The timeliness of such a review stems from the growing industry need to solve more realistic and comprehensive production planning problems. First, several different basic lot sizing problems are defined. Many extensions of these problems have been proposed and the research basically expands in two opposite directions. The first line of research focuses on modeling the operational aspects in more detail. The discussion is organized around five aspects: the set ups, the characteristics of the production process, the inventory, demand side and rolling horizon. The second direction is towards more tactical and strategic models in which the lot sizing problem is a core substructure, such as integrated production-distribution planning or supplier selection. Recent advances in both directions are discussed. Finally, we give some concluding remarks and point out interesting areas for future research

PROPOSED CONCEPTUAL FRAMEWORK OF INVENTORY MANAGEMENT USING THE JUST-IN-TIME (JIT) PHILOSOPHY

The effectiveness of the proposed JIT inventory management model, while conceptually developed based on previous case studies, depends largely to both internal and external support mechanisms of the organization. While the JIT philosophy has manifested remarkable contributions to productivity and efficiency in the developed countries, much has yet to be gained from it in the developing countries. Some problems can confound the adoption and implementation of JIT in the third world.Sector, as in the case of Tanzania (Msimangin, 1993): financial constraints, inadequate supply of inputs required for the production mills to operate near capacity, international delivery delays, an inadequate transportation infrastructure, and unreliable product demand forecasts. These problems are also present in the Philippines. Zamora (1989) identified several additional problems encountered in the implementation of JIT components in the Philippine setting: resistance to change, socio-cultural barriers, and lack of training, The success of any model or framework using the JIT philosophy must address these prob- j lems firmly. As in other cases, the successfti implementation of the proposed inventory management framework using the JIT philosophy could be achieved if existing local conditions aw considered to suit the requirements of the model] Flexibility of model adoption is therefore necessary.Further, it is recommended that the proposed model be practically applied in applicable situations and empirical informal be obtained to improve the framework. In this sense, the proposed model will be tested as to its practical usefulness apart from being conceptual

Aplicación de tres métodos de solución al problema de dimensionamiento de lotes y MRP.

El contenido del presente documento muestra la aplicación de tres métodos de solución a partir del planteamiento de un problema de dimensionamiento de lotes: Solución mediante la Heurística de Silver – Meal, la Heurística de Balanceo de Período y Parte y la Heurística de Costo Mínimo Unitario. La evaluación de los métodos anteriormente mencionados se realizó de forma manual, a través de recursos bibliográficos proporcionados por el orientador de la asignatura: Control de Producción e Inventarios. Teniendo en cuenta los resultados obtenidos se realizó una comparación entre los mismos y se procedió a elegir la mejor solución la cual se ve justificada mediante una política de costo mínimo

Designing a supply network for a startup company

Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2010.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 86-88).Our thesis introduces a supply chain framework catered for startup companies. Startup companies face unique circumstances such as constraints on financial and human resources, and greater uncertainty in demand. From our work with XL Hybrids, a startup company that hybridizes aftermarket vehicles, as well as interviews and literature review, we have attempted to distill supply chain strategies that can be applied to startup companies. To plan XL Hybrids' supply chain, we developed models for the following aspects of their supply chain: production scheduling, capacity planning, inventory policy, and component distribution. By running different demand and pricing scenarios, we gained an understanding of the impact of these variables on the four aspects of XL Hybrid's supply chain. Based on the scenario analysis and supply chain framework that we developed, we recommend that XL Hybrids be conservative with capacity expansion while strategically sourcing key components after considering volume discounts and different distribution methods.by Marcus S. Causton and Jianmin Wu.M.Eng.in Logistic

Optimal lot-sizing, pricing, and product intergenerational lifestyle decisions for the case of disruptive innovations in fashion

The objective of this dissertation is to determine production schedules, production quantities, selling prices, and new product introduction timing to fulfill deterministic price-dependent demand for a series of products in such a way as to maximize profit per period. In order to accomplish the above task, some main assumptions are made. First, it is assumed that the series of products being considered are associated with sequential non-disruptive innovations in technology as well as disruptive innovations in fashion. That is to say, the products represent subsequent generations in the same family of products in an industry that experiences repeated minor technological innovations and in which product success is due in part to fashionability (Fisher, 1997). Second, it is assumed that the planning horizon is sufficiently long and product lifecycles are sufficiently short that several generations of the product family are planned. Third, it is assumed that the producer is following a solo-product roll strategy (Billington, Lee, & Tang, 1998). This means that the inventory of one product iteration is exhausted at the same time that the next product iteration is introduced and ready for sale. Fourth, it is assumed that demand for each product iteration is governed by a modified version of the Bass (1969) diffusion model that incorporates price. Fifth, it is assumed that the various demand and cost characteristics being considered do not change from one product iteration to the next. Sixth, it is assumed that no backlog of demand is maintained and that any unmet demand is lost. Seventh, it is assumed that the manufacturer is a monopolist or at least the dominant member of a market that is made up of it and smaller competitors that are not large enough to affect the market in a meaningful way. The formulated profit maximization problem uses the Thomas (1970) model which in turn depends in its solution on theorems first presented by Wagner and Whitin (1958a). An extensive numerical study that aims at examining the sensitivity of the planned product lifecycle length and profit per period to changes in model parameters is performed using software developed especially for that purpose. The results of the analysis reveal that the above two measures are more sensitive to changes in market-oriented parameters than to changes in operations-oriented parameters. Managerial implications of the research findings are discussed