A heuristic for assigning facilities to locations to minimize WIP travel distance in a linear facility

Many manufacturing systems require an assignment of machines to locations along a straight track, so as to optimize material flow. This paper uses a cut approach to the corresponding quadratic assignment problem, and derives a heuristic which generates a good solution. In addition, a modified lower bound to the assignment problem is also developed, which is always better than the classical lower bound. Results showing the performance of the heuristic are demonstrated, along with a comparison of the modified and classical lower bound. In almost all the test problems, the solution generated by the heuristic was either optimal or better than any solution obtained by other methods. Extension of the heuristic to more general cases also is considered.     

Component allocation to balance workload in printed circuit card assembly systems

Component allocation in printed circuit card assembly systems is a special case of the classical mixed-model assembly line balancing problem and involves assigning component types to machines to achieve specific production objectives. In this paper the component allocation problem is considered for the scenario where there are two or more placement machines (possibly nonidentical) and the objective is to balance, for every card type, a combination of the card assembly time and the machine setup time. A mathematical formulation of the problem is developed for a class of placement machines. Two alternative solution approaches are presented: a list-processing-based heuristic for a simple version of the problem, and a linear-programming-based branch-and-bound procedure for the general component allocation problem. Industrial case study results are presented for each approach that indicate expected throughput improvements of up to 8-10% over the company's current procedure, with much less direct effort required by the process engineer.     

Development of a Rat Model to Test the Nutritional Equivalency of Traditional vs Fabricated Foods: Cheddar Cheese vs Fabricated Cheddar Cheese

Based on the Food & Drug Administration's proposed 1978 standards for “nutritional equivalency,” we have developed a biological assay designed to test the “nutritional equivalency” of traditional vs fabricated foods using cheddar cheese and fabricated cheddar cheese as examples. Diets were formulated that lacked the FDA proposed vitamin and mineral requirements (riboflavin, vitamins B-12 and A, calcium, phosphorus, zinc) for cheese substitutes. By adding traditional or fabricated cheddar cheese to such diets, we were able to compare the overall presence and bioavailability of the vitamins/minerals required for nutritional equivalency. Throughout the 28 day test, the fabricated cheddar cheese did not support the growth of male Sprague-Dawley rats as well as cheddar cheese did.