Suchergebnisse

AbstractThis article concerns the scheduling of n jobs around a common due date, so as to minimize the average total earliness plus total lateness of the jobs. Optimality conditions for the problem are developed, based on its equivalence to an easy scheduling problem. It seems that this problem inherently has a huge number of optimal solutions and an algorithm is developed to find many of them. The model is extended to allow for the availability of multiple parallel processors and an efficient algorithm is developed for that problem. In this more general case also, the algorithm permits great flexibility in finding an optimal schedule.

AbstractLarge-scale resource extraction projects often create obstacles for the protection, maintenance, and inheritance of indigenous cultural heritage. In this article we detail some of the challenges and opportunities arising from our collaborative partnership with the community of the Lihir Islands in Papua New Guinea, which is seeking to establish, inform, and resource a formal cultural heritage management program in the context of a large-scale gold-mining operation. The general approach to this collaborative venture involves the application of a specific development tool, the Stepping Stones for Cultural Heritage program. This consultative process is innovative in both Melanesia and the context of resource extraction, but also more generally within the field of cultural heritage. We describe the outcomes of this process and some of the initial pilot projects, one of which was based on the recording of traditional Lihirian songs. We also argue that while the mine places greater pressure upon Lihirian cultural heritage, it also presents Lihirians with the opportunity to realize a vision of their cultural future that is beyond the reach of many other indigenous communities.

AbstractWe study the problem of minimizing the makespan in no‐wait two‐machine open shops producing multiple products using lot streaming. In no‐wait open shop scheduling, sublot sizes are necessarily consistent; i.e., they remain the same over all machines. This intractable problem requires finding sublot sizes, a product sequence for each machine, and a machine sequence for each product. We develop a dynamic programming algorithm to generate all the dominant schedule profiles for each product that are required to formulate the open shop problem as a generalized traveling salesman problem. This problem is equivalent to a classical traveling salesman problem with a pseudopolynomial number of cities. We develop and test a computationally efficient heuristic for the open shop problem. Our results indicate that solutions can quickly be found for two machine open shops with up to 50 products. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005