摘要:

AbstractThe resource leveling problem for a construction system producing a stream of output units is considered. The system is modeled using a critical‐path‐analysis activity network, from which anextended networkis developed for an integrated planning effort of all output units. Activityintensityvariables are defined which measure activity demand rates for resources and consequent activity durations for the production of each output unit. A heuristic approach consisting of an iterative nonlinear programming procedure is presented which computes activity durations (intensities) for the minimization of resource capacity costs subject to meeting construction due dates. The application to a major ship overhaul project is described, in which the procedure was used to level workloads of the various labor–trade

ISSN:0028-1441    

DOI:10.1002/nav.3800300202

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn this article we extend our previous work on the continuous single‐module design problem to the multiple‐module case. It is assumed that there is a fixed cost associated with each additional module used. The Kuhn–Tucker conditions characterize local optima among which there is a global optimum. Modules are associated with partitions and a special class,guillotine partitions, are characterized. Branch‐and‐bound, partial enumeration, and heuristic procedures for finding optimum or good guillotine partitions are discussed and illustrated with

ISSN:0028-1441    

DOI:10.1002/nav.3800300203

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe individual and social optimum control policies for entry to anM/M//1 queue serving several classes of customers have been shown to be control‐limit policies. The technique of policy iteration provides the social optimum policy for such a queue in a straightforward manner. In this article, the problem of finding the optimal control policy for theM/Ek/1 system is solved, thereby expanding the potential applicability of the solutions developed. The Markovian nature of the queueing system is preserved by considering the service as havingksequential phases, each with independent, identically distributed, exponential service times, through which a customer must pass to be serviced. The optimal policy derived by policy iteration for such a system is likely to be difficult to use because it requires knowledge of the number of phases rather than customers in the system when an arrival occurs. To circumvent this difficulty, a heuristic is used to find a good usable (implementable) solution. In addition, a mixed‐integer program is developed which yields the optimal implementable solution when sol

ISSN:0028-1441    

DOI:10.1002/nav.3800300204

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

年代:1983

数据来源: WILEY

摘要:

AbstractAn optimization method is given for solving problems where a portion of the explicit mathematical form is unknown but can be evaluated. The solution scheme is an iterative process utilizing optimization and subsystem evaluation (such as via simulation). Conditions for the convergence of the iterative process are given. Several published application articles are noted as using this basic methodology. The method is superior to most other numerical optimization procedures. However, the class of problems for which the method is applicable is restricted to problems with enough known structure to generate a convergent iterative procedure. Three numerical examples are given and comparisons made with several other methods of optimizing unknown systems.

ISSN:0028-1441    

DOI:10.1002/nav.3800300205

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

年代:1983

数据来源: WILEY

摘要:

AbstractThis article develops a Lanchester‐type model of large‐scale conventional ground combat between two opposing forces in a “sector”. It is shown that nonlinear Helmbold‐type equations of warfare with operational losses may be used to represent the loss‐rate curves that have been used in many aggregated‐force models. These nonlinear differential equations are used to model the attrition of combat capability (as quantified by a so‐called firepower index) in conjunction with a rate‐of‐advance equation that relates motion of the contact zone (or FEBA) between the opposing forces to the force ratio and tactical decisions of the combatants. This simplified auxiliary model is then used to develop some important insights into the dynamics of FEBA movement used in large‐scale aggregated‐force models. Different types of behavior for FEBA movement over time are shown to correspond to different ranges of values for the initial force ratio, for example, an attack will “stall out” for a range of initial force ratios above a specific threshold value, but it will “break out” for force ratios above a second specific threshold value. Such FEBA‐movement predictions are essentially based on being able to forecast cha

ISSN:0028-1441    

DOI:10.1002/nav.3800300206

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn this article we consider the optimal control of anM[X]/M/squeue,s≧ 1. In addition to Poisson bulk arrivals we incorporate a reneging function. Subject to control are an admission pricepand the service rate μ. Thus, throughp, balking response is induced. Whenicustomers are present a costh(i,μ,p) per unit time is incurred, discounted continuously. Formulated as a continuous time Markov decision process, conditions are given under which the optimal admission price and optimal service rate are each nondecreasing functions ofi. In Section 4 we indicate how the infinite state space may be truncated to a finite state space for computational purpo

ISSN:0028-1441    

DOI:10.1002/nav.3800300207

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn this article, we describe a new algorithm for solving all‐integer, integer programming problems. We generate upper bounds on the decision variables, and use these bounds to create an advanced starting point for a dual all‐integer cutting plane algorithm. In addition, we use a constraint derived from the objective function to speed progress toward the optimal solution. Our basic vehicle is the dual all‐integer algorithm of Gomory, but we incorporate certain row‐ and column‐selection criteria which partially avoid the problem of dual‐degenerate iterations. We present the results of computatio

ISSN:0028-1441    

DOI:10.1002/nav.3800300208

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

年代:1983

数据来源: WILEY

摘要:

AbstractConsider a birth and death process starting in state 0. Keilson has shown by analytical arguments that the time of first passage into statenhas an increasing failure rate (IFR) distribution. We present a probabilistic proof for this. In addition, our proof shows that for a nonnegative diffusion process, the first passage time from state 0 to any statexis IFR.

ISSN:0028-1441    

DOI:10.1002/nav.3800300209

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn this article a branch‐and‐bound algorithm is proposed for solving the quadratic assignment problem. Using symmetric properties of the problem, the algorithm eliminates “mirror image” branches, thus reducing the search effort. Several routines that transform the procedure into an efficient heuristic are also implemented. These include certain 2‐way and 4‐way exchanges, selective branching rules, and the use of variable upper‐bounding techniques for enhancing the speed of fathoming. The computational results are quite encouraging. As an exact scheme, the algorithm solved the 12‐facility problem of Nugent et al. and the 19‐facility problem of Elshafei. More importantly, as a heuristic, the procedure produced the best known solutions for all well‐known problems in the literature, and produced improved solutio

ISSN:0028-1441    

DOI:10.1002/nav.3800300210

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe problem dealt with in this article is as follows. There aren“demand points” on a sphere. Each demand point has a weight which is a positive constant. A facility must be located so that the maximum of the weighted distances (distances are the shortest arcs on the surface of the sphere) is minimized; this is called the minimax problem. Alternatively, in the maximin problem, the minimum weighted distance is maximized. A setup cost associated with each demand point may be added for generality. It is shown that any maximin problem can be reparametrized into a minimax problem. A method for finding local minimax points is described and conditions under which these are global are derived. Finally, an efficient algorithm for finding the global minimax point is construc

ISSN:0028-1441    

DOI:10.1002/nav.3800300211

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

年代:1983

数据来源: WILEY