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101.
In planar location problems with barriers one considers regions which are forbidden for the siting of new facilities as well as for trespassing. These problems are important since they model various actual applications. The resulting mathematical models have a nonconvex objective function and are therefore difficult to tackle using standard methods of location theory even in the case of simple barrier shapes and distance functions. For the case of center objectives with barrier distances obtained from the rectilinear or Manhattan metric, it is shown that the problem can be solved in polynomial time by identifying a dominating set. The resulting genuinely polynomial algorithm can be combined with bound computations which are derived from solving closely connected restricted location and network location problems. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 647–665, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10038 相似文献
102.
Gerhard Schroeter 《海军后勤学研究》1984,31(3):373-385
The coverage C of area targets by salvos of weapons generally varies randomly, because of random target location and weapon impact point fluctuations. A third source of variation appears when, instead of an area target, a multiple-element target is considered, consisting of m point targets distributed randomly and independently of one another around the target center. A multiple-integral expression is derived for the probability pk of killing exactly k target elements. It is shown that pk is a linear function of the higher moments, of the order k to m, of the area coverage C. More explicit expressions are derived for the case of two weapons and for circular-symmetric functions. Similar to well-known results for the expectation and variance of coverage of area targets, these expressions can be evaluated by numerical quadrature. Furthermore, the coverage problem in which all underlying functions are Gaussian can be completely solved in closed form. For such a problem, with two weapons, numerical results are presented. They show that the distribution of k can be approximated by a binomial distribution only if the target center and weapon impact point fluctuations are small. 相似文献
103.
This article examines the influence of both production rate and learning on airframe program costs. A dynamic multiple-output production model is developed and is used to observe the cost impact of changes in production rate and learning. Several simulations are performed to demonstrate the sensitivity of the optimal time path of cost to changes in the model parameters. The model is applied by estimating parameters from the F102 airframe program. 相似文献
104.
K. D. Glazebrook 《海军后勤学研究》1981,28(2):289-300
It is shown that there is an optimal strategy for a class of stochastic scheduling problems which is nonpreemptive. The results which yield this conclusion are generalizations of previous ones due to Glazebrook and Gittins. These new results also lead to an evaluation of the performance of nonpreemptive strategies in a large class of problems of practical interest. 相似文献
105.
106.
This article presents several single-echelon, single-item, static demand inventory models for situations in which, during the stockout period, a fraction b of the demand is backordered and the remaining fraction 1 - b is lost forever. Both deterministic and stochastic demand are considered. although the case of stochastic demand is treated heuristically. In each situation, a mathematical model representing the average annual cost of operating the inventory system is developed. and an optimum operating policy derived. At the extremes b=1 and b=0 the models presented reduce to the usual backorders and lost sales cases, respectively. 相似文献
107.
The effectiveness of Johnson's Approximate Method (JAM) for the 3 × n job shop scheduling problems was examined on 1,500 test cases with n ranging from 6 to 50 and with the processing times Ai, Bi, Ci (for item i on machines A, B, C) being uniformly and normally distributed. JAM proved to be quite effective for the case Bi ? max (Ai, Ci) and optimal for Bi, ? min (Ai, Ci). 相似文献
108.
K.-H. Waldmann 《海军后勤学研究》1986,33(3):399-412
Simple criteria are found for reducing the computational effort in multistage Bayesian acceptance sampling. Regions of optimality are given for both terminal actions accept and reject. Also, criteria are presented for detecting nonoptimality of sets of sample sizes. Finally, nearly optimal (z,c?,c+)-sampling plans are constructed by restricting attention to a small subset of sample sizes. 相似文献
109.
110.
A method of life testing is proposed which combines both ordinary and accelerated life-testing procedures. It is assumed that an item can be tested either in a standard environment or under stress. The amount of stress is fixed in advance and is the same for all items to be tested However, the time x at which an item on lest is taken out of the standard environment and put under stress can be chosen by the experimenter subject to a given cost structure. When an item is put under stress its lifetime is changed by the factor α. Let the random variable T denote the lifetime of an item in the standard environment, and let γ denote its lifetime under the partially accelerated test procedure just described. Then Y = T if T ≦ x, and Y = x + α (T > x) if T > x. It is assumed that T has an exponential distribution with parameter θ. The estimation of θ and α and the optimal design of a partially accelerated life test are studied in the framework of Bayesian decision theory. 相似文献