摘要:

AbstractA complete logistical planning model of a firm or public system should include activities having to do with the procurement of supplies. Not infrequently, however, procurement aspects are difficult to model because of their relatively complex and evanescent nature. This raises the issue of how to build an overall logistics model in spite of such difficulties. This paper offers some suggestions toward this end which enable the procurement side of a model to be simplified via commodity aggregation in a “controlled” way, that is, in such a manner that the modeler can know and control in advance of solving his model how much loss of accuracy will be incurred for the solutions to the (aggregated) overall mo

ISSN:0028-1441    

DOI:10.1002/nav.3800240202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThis paper describes a node covering algorithm, i.e., a procedure for finding a smallest set of nodes covering all edges of an arbitrary graph. The algorithm is based on the concept of a dual node‐clique set, which allows us to identify partial covers associated with integer dual feasible solutions to the linear programming equivalent of the node covering problem. An initial partial cover with the above property is first found by a labeling procedure. Another labeling procedure then successively modifies the dual node‐clique set, so that more and more edges are covered, i.e., the (primal) infeasibility of the solution is gradually reduced, while integrality and dual feasibility are preserved. When this cannot be continued, the problem is partitioned and the procedure applied to the resulting subproblems. While the steps of the algorithm correspond to sequences of dual simplex pivots, these are carried out implicitly, by labeling. The procedure is illustrated by examples, and some early computational experience is reported. We conclude with a discussion of potential improvements and extensi

ISSN:0028-1441    

DOI:10.1002/nav.3800240203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA two‐dimensional state space Markov Model of a Manpower System with special structure is analyzed. Examples are given from the military services. The probabilistic properties are discussed in detail with emphasis on computation. The basic equations of manpower stocks and flows are analyze

ISSN:0028-1441    

DOI:10.1002/nav.3800240204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThis paper is concerned with the problem of simultaneously setting price and production levels for an exponentially decaying product. Such products suffer a loss in utility which is proportional to the total quantity of stock on hand. A continuous review, deterministic demand model is considered. The optimal ordering decision quantity is derived and its sensitivity to changes in perishability and product price is considered. The joint ordering pricing decision is also computed and consideration of parametric changes of these decisions indicates a non‐monotonic response for optimal price to changes in product decay. Issues of market entry and extensions to a model with shortages are also analyze

ISSN:0028-1441    

DOI:10.1002/nav.3800240205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThere are givenk(⩾ 2) univariate cumulative distribution functions (c.d.f.'s) G(x; θi) indexed by a real‐valued parameter θi, i=1,…, k. Assume that G(x; θi) is stochastically increasing in θi. In this paper interval estimation on the ithsmallest of the θ's and related topics are studied. Applications are considered for location parameter, normal variance, binomial parameter, and Poisson

ISSN:0028-1441    

DOI:10.1002/nav.3800240206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractWe present some results forM/M/1 queues with finite capacities with delayed feedback. The delay in the feedback to anM/M/1 queue is modelled as anotherM‐server queue with a finite capacity. The steady state probabilities for the two dimensional Markov process {N(t),M(t)} are solved whenN(t) = queue length at server 1 attandM(t) = queue length at server 2 att.It is shown that a matrix operation can be performed to obtain the steady state probabilities. The eigenvalues of the operator and its eigenvectors are found. The problem is solved by fitting boundary conditions to the general solution and by normalizing. A sample problem is run to show that the solution methods can be programmed and meaningful results obtained numericall

ISSN:0028-1441    

DOI:10.1002/nav.3800240207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractWe consider a queuing system in which both customers and servers may be of several types. The distribution of a customer's service time is assumed to depend on both the customer's type and the type of server to which he is assigned. For a model with two servers and two customer types, conditions are presented which ensure that the discounted number of service completions is maximized by assigning customers with longer service times to faster servers. Generalizations to more complex models are discussed.

ISSN:0028-1441    

DOI:10.1002/nav.3800240208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractConsider a standard linear programming problem and suppose that there are bounds available for the decision variables such that those bounds are not violated at an optimal solution of the problem (but they may be violated at some other feasible solutions of the problem). Thus, these bounds may not appear explicitly in the problem, but rather they may have been derived from some prior knowledge about an optimal solution or from the explicit constraints of the problem.In this paper, the bounds on variables are used to compute bounds on the optimal value when the problem is being solved by the simplex method. The latter bounds may then be used as a termination criteria for the simples iterations for the purpose of finding a “sufficiently good” near optimal solution. The bounds proposed are such that the computational effort in evaluating them is insignificant compared to that involved in the simplex iterations. A numerical example is given to demonstrate their performa

ISSN:0028-1441    

DOI:10.1002/nav.3800240209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThis paper presents the details for applying and specializing the work of Saigal [28] and Hartman and Lasdon [16]to develop a primal partitioning code for the multicommodity transportation problem. The emphasis of the paper is in presenting efficient data structure techniques for exploiting the underlying network structure of this class of problems. Computational experience with test problems whose corresponding linear programming formulation has over 400 rows and 2,000 columns is presented.

ISSN:0028-1441    

DOI:10.1002/nav.3800240210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA class of convex programming problems with network type constraints is addressed and an algorithm for obtaining the optimal solution is described. Thestochastic transportation problem(minimize shipping costs plus expected holding and shortage costs at demand points subject to limitations on supply) is shown to be amenable to the solution technique presented. Network problems whose objective function is non‐separable and network problems with side constraints are also shown to be solvable by the algorithm. Several large stochastic transportation problems with up to 15,000 variables and non‐negativity constraints and 50 supply constraints are sol

ISSN:0028-1441    

DOI:10.1002/nav.3800240211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY