This paper considers a double-row layout problem with shared clearances in the context of semiconductor manufacturing. By sharing some clearances, reductions in both layout area and material handling cost of approximately 7–10% are achieved. Along with minimal clearances for separating adjacent machines, clearances that can be shared by adjacent machines are considered. The shared clearances ma...

The single row routing problem is considered. It is shown that the use of backward moves can reduce street congestion when four or more tracks per street are available. We obtain an O((2k)!k*n*log k) algorithm to determine whether or not n nodes can be wired when only k tracks per street are available. An efficient algorithm is obtained for the case when wires are not permitted to cross streets...

Pinus taeda L. plantations in the United States are typically established using rows that are spaced 3 to 4 m apart. Although one company now plants pines in 6.1 m rows, reports on performance using this row spacing are rare. This paper provides a case study (established at the Solon Dixon Forestry Education Center) that compares two densities [672 vs 1344 seedlings per ha (SPH)] when fixing th...

In this article we review the 2011 International Planning Competition. We give an overview of the history of the competition, discussing how it has developed since its first edition in 1998. The 2011 competition was run in three main separate tracks: the Deterministic (Classical) Track; the Learning Track; and the Uncertainty Track. Each track proposed its own distinct set of new challenges and...

With recent, dramatic changes in Arctic sea ice and the Antarctic ice sheets, the importance of monitoring the climate of the polar regions has never been greater. While many individual global satellite products exist, the AVHRR Polar Pathfinder products provide a comprehensive set of variables that can be used to study trends and interactions within the Arctic and Antarctic climate systems. Th...

In the article “The Availability of Competitive Foods and Beverages to Middle School Students in Appalachian Virginia Before Implementation of the 2014 Smart Snacks in School Standards,” the author made an error in calculating the order of data presented in Table 2. Changes do not affect study results. Numbers changed in all columns and rows of Table 2. In addition, changes were made to the text.

We derive approximations for the service levels of two-echelon inventory systems with lost sales and Poisson demand. Our method is simple and accurate for a very broad range of problem instances, including cases with both high and low service levels. In contrast, existing methods only perform well for limited problem settings, or under restrictive assumptions.

The initial database search cost deteriorates due to record additions, deletions and updates performed during the system operation. Previous studies proposed strategies for selecting the optimum maintenance points by making various assumptions about the rate of database deterioration, the database planning period, the maintenance interval, etc. However, the studies did not express the optimum m...