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This paper examines the scheduling of a drug packaging operation which requires assigning resources to production lines during set-up in order to satisfy product specifications. We present mixed integer programming models of the problem and develop a Lagrangian heuristic to solve the models. Real data from a drug company and randomly generated data are used to test the models. Results show the efficacy of our solution approach to find good feasible schedules. We discuss some of the practical benefits and potential issues about the production schedules obtained using the models. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2010.05.027 Byline: Dengfeng Zhang (a), Renato de Matta (b), Timothy J. Lowe (b) Keywords: Retailing; Production; Pricing; Channel coordination Abstract: With the emergence of virtual market places, consignment selling has been thriving at an unprecedented pace. It has been shown in the literature that inefficiency exists in a decentralized consignment channel with a single revenue share agreement. In our study, we analyze contracts observed in practice that contain bonus or side payment terms, and examine whether they can promote better coordination between the supplier and the retailer. We found that no multi-tier Bonus system can fully coordinate the consignment channel. However, fine adjustments of bonus parameters can bring the channel close to full coordination. Additionally, we found revenue sharing with side payment contracts not only fully coordinate the channel, but they can also be customized to meet the needs of small, medium and large suppliers for extra retailer services such as warehousing and transportation. Managerial insights on how to design the contracts from the supplier, retailer and channel perspectives are discussed in the paper. Author Affiliation: (a) Department of Computing and Decision Sciences, Lingnan University, Tuen Mun, Hong Kong (b) Department of Management Sciences, University of Iowa, Iowa City, IA 52242-1000, United States Article History: Received 18 December 2008; Accepted 19 May 2010 Article Note: (footnote) [star] The authors are grateful to two anonymous referees and the editor for their valuable comments and suggestions that helped improve the paper.

In the face of shorter product life cycles, designing products with modular component parts can shorten product development time and speed up the introduction of new products in the market. Utilizing stylized models, we examine the reuse/redesign, quality, speed-to-market, and marketing decisions for two consecutive generations of a multicomponent modular product. With modularity that assumes a stable product architecture, each component can be improved by incurring a design cost that is convex increasing in the level of quality. Our study generates the following insights. When development start-up (fixed) cost is negligible, it is profitable to upgrade every component part; otherwise, it is beneficial to reuse some of the existing parts without making any design improvements in order to save on development cost. In an effort to reduce product development time while maximizing profit, we found solid evidence that the productivity level in developing every component part can be a key driver of speed-to-market. Individually, a new product launch time postponement and an R&D budget increase can lead to improvements in component part quality and overall product quality, but our models show that better improvement in quality can be achieved from launch time postponement (budget increase) when product design teams have low (high) product development productivity. Finally, when the marginal cost of producing the new product is equal to that of the old product, it is optimal to remove the old product from the market and sell only the new product. Index Terms--Component reuse, modular product design, nonlinear programming, product development.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2007.09.045 Byline: Renato de Matta (a), Emmanuel Peters (b) Keywords: OR in developing countries; Transportation; Integer programming Abstract: In developing work schedules, the job assignment flexibility exploits the variety of available skills, thus enabling the assignment of workers to perform different jobs. In this study, we investigate the problem of finding the mix of primary and secondary jobs in short term work schedules to meet, at minimum cost, the daily service requirements of an inter-city bus transit firm in Andra Pradesh India operating multiple fleet types. We formulate the problem as a set covering model with resource allocation constraints. We develop a branch-and-price procedure to solve the model. Computational results are provided. Author Affiliation: (a) Department of Management Sciences, College of Business Administration, University of Iowa, Iowa City, IA 52242, United States (b) Pfizer Inc., 201 Tabor Road 86-1, Morris Plains, NJ 07950, United States Article History: Received 9 January 2007; Accepted 28 September 2007

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2006.02.032 Byline: Emmanuel Peters (a), Renato de Matta (b), Warren Boe (b) Keywords: Transportation; Manpower scheduling; Large scale optimization; Operations research in developing countries Abstract: In recent years, planning and management of operations of transportation companies has become increasingly complex as tighter financial constraints affect the ability to respond to changing demands for travel. This paper investigates how a firm can reduce its total labor cost, enhance the flexibility of its operations and improve worker productivity and utilization by determining the right mix of jobs in work schedules. Using a method we have developed to generate low cost work schedules for bus drivers of an inter-city transport system in India, we study the changes in worker productivity and utilization when a mix of primary and secondary jobs is built in work schedules. We also investigate other factors that can strongly influence worker productivity and utilization such as the amount of overtime in work schedules, the level of job assignment flexibility, and staff size. Test results and discussions of managerial implications are presented. Author Affiliation: (a) Pfizer Inc., 201 Tabor Road 86-1, Morris Plains, NJ 07950, United States (b) Department of Management Sciences, College of Business Administration, University of Iowa, 108 John Pappajohn Business Building, Suite S210, Iowa City, IA 52242, United States Article History: Received 13 December 2004; Accepted 16 February 2006

In this paper we study lot-sizing and changeover decisions in production schedules that are implemented on a rolling-horizon basis. The study is carried out by comparing production schedules for the packaging operations of a pharmaceutical company that produces various products on several capacitated production lines. The schedules are obtained by solving a mixed-integer programming formulation by using a heuristic procedure. We examine the effects of the number of periods in the planning horizon, the starting inventory and the demand fluctuation on the schedules. We show empirically that the saving in annual production cost diminishes rapidly as more demand periods are added to the planning horizon. Computational results are reported., 1. Introduction The uncertain and limited information about demands for future products favors the use of finite-horizon decision models by manufacturing industries in planning and scheduling production. Demands are usually [...]

This article considers an exporter who produces multiple products at geographically separated production plants to meet a stream of deterministic overseas demands over a planning horizon. Each production plant uses either a direct delivery mode, which sends pre-loaded cargos of a product directly from its production facility to the ocean port, or a consolidated delivery mode where products are consolidated into outbound ocean cargos at the facility of a third-party logistics firm and delivered to the ocean port. The exporter's problem is to develop a minimum-cost production and delivery plan for the entire supply chain over a finite planning horizon. The problem is modeled as a mixed-integer program and it is shown to be NP-hard even for the case with one production plant. Two distinct but related decisions characterize the problem, namely, the product delivery mode selection decision and the production scheduling decision. The natural separation of these decisions is exploited in a Benders decomposition solution procedure. An important finding of this study is that the exporter can extract the most value from integrating consolidated deliveries in the production and distribution plan when plants have modest production costs and demand variability is high. [ABSTRACT FROM PUBLISHER]

In the face of shorter product life cycles, designing products with modular component parts can shorten product development time and speed up the introduction of new products in the market. Utilizing stylized models, we examine the reuse/redesign, quality, speed-to-market, and marketing decisions for two consecutive generations of a multicomponent modular product. With modularity that assumes a stable product architecture, each component can be improved by incurring a design cost that is convex increasing in the level of quality. Our study generates the following insights. When development start-up (fixed) cost is negligible, it is profitable to upgrade every component part; otherwise, it is beneficial to reuse some of the existing parts without making any design improvements in order to save on development cost. In an effort to reduce product development time while maximizing profit, we found solid evidence that the productivity level in developing every component part can be a key driver of speed- to-market. Individually, a new product launch time postponement and an R&D budget increase can lead to improvements in component part quality and overall product quality, but our models show that better improvement in quality can be achieved from launch time postponement (budget increase) when product design teams have low (high) product development productivity. Finally, when the marginal cost of producing the new product is equal to that of the old product, it is optimal to remove the old product from the market and sell only the new product. [ABSTRACT FROM AUTHOR]