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Smith, A. R.; Bartholomew, D. J.
doi: 10.1057/jors.1988.41pmid: N/A
AbstractThe Manpower Planning Study Group of the Operational Research Society was formed on 16th November 1967. This paper traces the growth of manpower planning in the United Kingdom from its origins in the Second World War to the present day. It identifies a series of stages, starting with the beginnings and growing awareness of the 1950s and early 1960s, which led on to an explosive growth between 1965 and 1970, and the lengthy period of consolidation thereafter. It places on record the interest and contributions of many individuals and organizations who laid the foundations of manpower planning in this country, and review trends in methodology and the growing role of computers. The paper concludes with some notes on possible future developments.
doi: 10.1057/jors.1988.42pmid: N/A
AbstractThis paper focusses on an often encountered constraint in real-life cutting-stock problems. The constraints require that pieces corresponding to the same order are not spread too much over the production run. This elimination of order spread is called pattern allocation or cutting sequencing. In this paper, a two-stage procedure to solve the two-dimensional pattern-allocation problem is suggested. The first stage consists of solving the cutting-stock problem without the sequencing constraint. In the second stage a sequencing problem is used for the ordering of the cutting patterns in an optimal or near-optimal way. The sequencing problem is formulated as a travelling-salesman model, and the model is solved by Lin's 3-optimal method. Computational experience is reported from a case study in the glass industry.
Ferris, M. C.; Philpott, A. B.
doi: 10.1057/jors.1988.43pmid: N/A
AbstractA new polynomial-time algorithm for linear programming was announced by Narendra Karmarkar of Bell Laboratories in 1984. This algorithm is claimed by Bell Labs significantly to outperform the simplex method. Many numerical experiments have been carried out by other workers in the field which show a much smaller iteration count than the simplex method but larger computational times. Some have shown that, by using advanced numerical linear algebra and heuristics to exploit the problem structure, it is possible occasionally to beat the simplex method even in terms of computation time. A brief description of the main features of Karmarkar's algorithm is presented, along with the results of some numerical experiments. Another closely related interior-point method which involves the rescaling of the variables is also discussed, and some details of the sparse matrix manipulations involved in an implementation of the algorithm are mentioned.
doi: 10.1057/jors.1988.44pmid: N/A
AbstractGiven m semi-identical processors which are parallel processors all working with the same speed but in different time intervals of availability and n independent tasks with deadlines, the problem of constructing a feasible pre-emptive schedule is examined. We present an O (nm log n) time algorithm to construct such a schedule whenever one exists. We show that the number of induced pre-emptions is proportional to the total number of processing intervals and deadlines.
doi: 10.1057/jors.1988.45pmid: N/A
AbstractViewing the GI/G/c queue as a service system alternating between two basic states—that of a loaded (non-empty) GI/G/1 queue and that of a GI/G/∞ queue (dependent, respectively, on whether all servers in the GI/G/c queue are busy or otherwise)—approximations for the components of the mixture distribution of the steady-state probabilities are derived. The M/G/c queue is separately treated. Two imposed prerequisites, that only minimal prior information about the queue will be required and that no numeric method be needed other than a root-finding algorithm, are strictly adhered to. The accuracy attained is generally satisfactory, while remarkable algebraic simplicity is preserved.
doi: 10.1057/jors.1988.46pmid: N/A
AbstractThis paper introduces a methodology for the assessment of a decision-maker's utility function, based on interactions requiring relatively easy responses of the implicit trade-off type, i.e. similar to responses required in STEM or goal programming methods. The estimation of the value-function model to represent preferences is useful in ranking or pruning elements of the decision space. Inputs required from the decision-maker are, however, less demanding than the pairwise comparisons (or similar preference statements) typically required by value-function models. The methodology thus appears to be appropriate for relatively large numbers of criteria. An algorithm for implementing the proposed methodology for finite action spaces is developed and applied to examples involving up to 15 criteria.
Lanzenauer, Christoph Haehling Von
doi: 10.1057/jors.1988.47pmid: N/A
AbstractA service-level constraint, defined over a fiscal period, is introduced which measures the amount short and restricts it to a managerially acceptable level. When demand is normal, it is shown that the derivation of the key inventory variables is independent of the parameters of the demand distribution. The service-level constraint is illustrated, and its managerial implications are discussed.
doi: 10.1057/jors.1988.48pmid: N/A
AbstractIn many stock-control systems the policy is to place an order if the stock balance has fallen to or below a reorder level and to order enough stock to bring the stock balance up to a maximum stock level. It is often the case that stock is sold singly but is replenished in multiples of some pack size. This note considers how the actual order size depends on the pack size and the amount by which the stock balance has fallen below the reorder level at the time an order is placed.
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