摘要:

AbstractWe consider state‐age‐dependent replacement policies for a multistate deteriorating system. We assume that operating cost rates and replacement costs are both functions of the underlying states. Replacement times and sojourn times in different states are all state‐dependent random variables. The optimization criterion is to minimize the expected long‐run cost rate. A policy‐improvement algorithm to derive the optimal policy is presented. We show that under reasonable assumptions, the optimal replacement policies have monotonic properties. In particular, when the failure‐rate functions are nonincreasing, or when all the replacement costs and the expected replacement times are independent of state, we show that the optimal policies are only state dependent. Examples are given to illustrate the structure of the optimal policies in the special case when the sojourntime distributions are Weibull. © 1994 John Wil

ISSN:0894-069X    

DOI:10.1002/1520-6750(199404)41:3<303::AID-NAV3220410302>3.0.CO;2-2

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe extended economic lot scheduling problem (EELSP) is concerned with scheduling the production of a set of items in a single facility to minimize the long‐run average holding, backlogging, and setup costs. Given an efficient cyclic production schedule for the EELSP, called the target schedule, we consider the problem of how to schedule production after a single schedule disruption. We propose a base stock policy, characterized by a base stock vector, that prescribes producing an item until its inventory level reaches the peak inventory of the target schedule corresponding to the item's position in the production sequence. We show that the base stock policy is always successful in recovering the target schedule. Moreover, the base stock policy recovers the target schedule at minimal excess over average cost whenever the backorder costs are proportional to the processing times. This condition holds, for example, when the value of the items is proportional to their processing times, and a common inventory carrying cost and a common service level is used for all the items. Alternatively, the proportionality condition holds if the inventory manager is willing to select the service levels from a certain set that is large enough to guarantee any minimal level of service, and then uses the imputed values for the backorder costs. When the proportionality condition holds we provide aclosed‐form expression for the total relevant excess over average cost of recovering the target schedule. We assess the performance of the base stock policy when the proportionality condition does not hold through a numerical study, and suggest some heuristic uses of the base stock policy. © 1994 John Wiley&Sons,

ISSN:0894-069X    

DOI:10.1002/1520-6750(199404)41:3<317::AID-NAV3220410303>3.0.CO;2-T

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis article deals with the problem of setting priorities for the execution of maintenance packages at randomly occurring opportunities. These opportunities are of restricted duration, implying that only a limited number of packages can be executed. The main idea proposed is to set up a model for determining the optimal execution time for the individual maintenance packages and to develop cost criteria for deviations from the optimal time. In this article we use the block replacement model, but the approach can be easily extended to include other optimization models as well. Using Monte Carlo simulation the performance of the method is compared with various heuristics, both for a two‐package and a multipackage case. © 1994 John Wiley&Sons, I

ISSN:0894-069X    

DOI:10.1002/1520-6750(199404)41:3<335::AID-NAV3220410304>3.0.CO;2-M

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

年代:1994

数据来源: WILEY

摘要:

AbstractWe discuss the two‐attribute warranty policy in which two types of warranty characteristics, such as product age and mileage in the y‐year‐m‐mile protection plan in the automobile industry, are employed simultaneously as criteria in determining the warranty eligibility of a failed product. Based on the Poisson regression model and von Neumann‐Morgenstern expected utility theory, we develop two kinds of two‐attribute warranty policies: afixedtwo‐attribute warranty policy in which all customers are offered the same warranty plan, and aflexibletwo‐attribute warranty policy in which customers are permitted to choose any warranty plan among the numerous plans furnished by the producer. A numerical example is presented to illustrate the procedure for determining the optimal warranty price in the fixed two‐attribute warranty model and for generating a set of warranty plans for the same warranty price in the flexible warranty model. It appears desirable from both the producers' and consumers' viewpoints to convert the classical single‐attribute warranty policy into a fixed two‐attribute policy or, even further, into a flexible two‐attribute policy. © 1

ISSN:0894-069X    

DOI:10.1002/1520-6750(199404)41:3<355::AID-NAV3220410305>3.0.CO;2-D

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis article examines a game of multiproduct technology adoption. We consider a duopoly model in which firms choose when to switch from a traditional single‐product technology to a more flexible and more expensive multiproduct technology. The multiproduct technology allows a firm to invade the other firm's market, creating a more competitive environment and reducing profits. We analyze this investment decision as a game of timing using two different equilibrium concepts. First, we utilize the “silent” equilibrium concept, where firms commit at time zero to a switching time. This concept would be applicable to situations where firms cannot observe each other's actions, or when the implementation of the technology requires long lead times and the investment decision is private information. Using this notion we find that both firms adopt the multiproduct technology simultaneously within a certain time interval. We then characterize this time interval in terms of cost and demand conditions. We also derive conditions under which sequential adoption of the multiproduct technology occurs. The second concept used is that of noisy equilibrium, where firms cannot precommit themselves to an adoption time. This concept is appropriate when investment decisions are common knowledge. In this case a firm can credibly threaten to immediately follow suit if the other firm decides to adopt. This threat is sufficient to ensure the collusive outcome where neither firm adopts the flexible technology. © 1994 John Wiley&Son

ISSN:0894-069X    

DOI:10.1002/1520-6750(199404)41:3<377::AID-NAV3220410306>3.0.CO;2-2

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

年代:1994

数据来源: WILEY

摘要:

AbstractGiven an ordered list ofnitems,ppossible positions, and integer profitscijfor assigning itemito positionj, the order‐preserving assignment problem consists of finding a profit‐optimal assignment that assigns items to contiguous positions while preserving the original ranking, i.e., the highest‐ranked item that will be assigned is assigned to position 1 and so on. Positions must be assigned contiguously starting with position one, but items need not be assigned to any particular position. We formulate the problem as a zero‐one linear program, derive a minimal description of the associated polytope by linear inequalities, show that the diameter of the polytope equals two, and give a linear‐time algorithm for the optimization problem, i.e., one that runs in time that is linear in the number of variables of the problem. We do this for both cases where at mostppositions and where exactlyppositions must be assigned and discuss briefly two modifications of the basic model. © 1994 John Wiley

ISSN:0894-069X    

DOI:10.1002/1520-6750(199404)41:3<395::AID-NAV3220410307>3.0.CO;2-W

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis article proposes an interactive paired comparison region elimination method for bicriterion integer mathematical programming problems. The new method isolates the best compromise solution by successively evaluating a pair of associated supported non‐dominated solutions. The efficiency of the method is tested by solving randomly generated problems based on varying shapes of efficient frontiers. When compared with the existing branch‐and‐bound method, the method was effective in reducing the burden on the decision maker. © 1994 John Wiley&Son

ISSN:0894-069X    

DOI:10.1002/1520-6750(199404)41:3<423::AID-NAV3220410308>3.0.CO;2-E

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

年代:1994

数据来源: WILEY

摘要:

AbstractWe present a branch‐and‐bound algorithm for globally minimizing a concave function over linear constraints and integer variables. Concave cost functions and integer variables arise in many applications, such as production planning, engineering design, and capacity expansion. To reduce the number of subproblems solved during the branch‐and‐bound search, we also develop a framework for computing new and existing penalties. Computational testing indicates that penalties based on the Tuy cutting plane provide large decreases in solution time for some problems. A combination of Driebeek‐Tomlin and Tuy penalties can provide further decreases in solution time. © 1994 John Wiley

ISSN:0894-069X    

DOI:10.1002/1520-6750(199404)41:3<435::AID-NAV3220410309>3.0.CO;2-6

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

年代:1994

数据来源: WILEY

摘要:

AbstractA wide variety of optimization problems have been approached with branch‐and‐bound methodology, most notably integer programming and continuous nonconvex programming. Penalty calculations provide a means to reduce the number of subproblems solved during the branch‐and‐bound search. We develop a new penalty based on the Tuy cutting plane for the nonconvex problem of globally minimizing a concave function over linear constraints and continuous variables. Computational testing with a branch‐and‐bound algorithm for concave minimization indicates that, for the problems solved, the penalty reduces solution time by a factor ranging from 1.2 to 7.2. © 1994 John Wil

ISSN:0894-069X    

DOI:10.1002/1520-6750(199404)41:3<455::AID-NAV3220410310>3.0.CO;2-Q

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

年代:1994

数据来源: WILEY

ISSN:0894-069X    

DOI:10.1002/1520-6750(199404)41:3<::AID-NAV3220410301>3.0.CO;2-Z

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

年代:1994

数据来源: WILEY