ISSN:0160-5682    

DOI:10.1057/jors.1993.195

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractProduction/inventory systems must attempt to cope with varying demand. This is traditionally done by applying theR,tinventory system after forecasting demand. If the demand is not stationary in mean and variance, this system relies on advanced forecasting models and may still be inadequate. A technique is presented which applies feedback control theory to the maintenance of a chosen level of safety stock. A term involving the rate of change of stock on hand is introduced to overcome the deficiencies of the standardR,treorder policy when dealing with erratic demand. Once the parameters for an individual application are chosen the technique may be automated on any spreadsheet or modelling package. Results are produced which indicate that this is a superior heuristic to the standardR,tsystem.

ISSN:0160-5682    

DOI:10.1057/jors.1993.196

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractGiven a set of points, we wish to design a network consisting of a primary link and a set of secondary links connecting the points to the primary link. The objective of the problem is to find the location and length of the primary link in order to minimize the sum of its weighted length and the weighted lengths of all secondary links. We assume that the weight of the secondary link from any point varies depending on the location of that point. In this paper, we describe efficient algorithms and their computer implementation for two scenarios of this problem. In the first scenario, only direct secondary links are allowed from each point to the primary link. In the second scenario, the secondary link from a point is allowed to pass through other points before reaching the primary link.

ISSN:0160-5682    

DOI:10.1057/jors.1993.197

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractThis paper presents a new solution approach to the discontinuous labour tour scheduling problem where the objective is to minimize the number of full-time employees required to satisfy forecast demand. Previous heuristic approaches have often limited the number of allowable tours by restricting labour scheduling flexibility in terms of shift length, shift start-times, days-off, meal-break placement, and other factors. These restrictions were essential to the tractability of the heuristic approaches but often resulted in solutions that contained a substantial amount of excess labour. In this study, we relaxed many of the restrictions on scheduling flexibility assumed in previous studies. The resulting problem environment contained more than two billion allowable tours, precluding the use of previous heuristic methods. Consequently, we developed a simulated annealing heuristic for solving the problem. An important facet of this new approach is an‘intelligent’improvement routine which eliminates the need for long run-times typically associated with simulated annealing algorithms. The simulated annealing framework does not rely on a special problem structure and our implementation rapidly converged to near-optimal solutions for all problems in the test environment.

ISSN:0160-5682    

DOI:10.1057/jors.1993.198

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractIn this paper, we propose a reference direction approach and an interactive algorithm to solve the general multiple objective integer linear programming problem. At each iteration, only one mixed integer linear programming problem is solved to find an (weak) efficient solution. Each intermediate solution is integer. The decision maker has to provide only the reference point at each iteration. No special software is required to implement the proposed algorithm. The algorithm is illustrated with an example.

ISSN:0160-5682    

DOI:10.1057/jors.1993.199

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractCurrency options have been used by risk averse firms to cover foreign exchange exposure, to profit from favourable exchange rate movements and to hedge the binary bidding situation. The aim of this paper is to establish a wider scope for currency options as a hedging tool for cases where the convertible amount is uncertain. The most appropriate option size derived using the concept of risk minimization is shown always to exceed the expected uncertain convertible amount.

ISSN:0160-5682    

DOI:10.1057/jors.1993.200

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractOne of the shortcomings of R&D evaluation is a lack of emphasis on analytical assessment of the value of an on-going R&D project. This paper addresses the problem concerning the distributive aspect of access to superior knowledge. Decision tree analysis and probability models appear to be appropriate tools for assessing the values of an intermediate result and patent reward of a firm's R&D decision in an environment of perfect information and oligopolistic competition. The assessed values are used as minimum prices acceptable to the firm when the knowledge is disseminated to the public. This paper will attempt to resolve this problem through the determination of the appropriate values of the reservation price of the first-stage invention in terms of the final reward and of a patent reward for which the inventor is willing to apply.

ISSN:0160-5682    

DOI:10.1057/jors.1993.201

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractThe classical no-shortage inventory policy is examined for the case of deteriorating items having a deterministic demand pattern with a linear (positive) trend. A heuristic model is developed to determine the optimal times for inventory replenishment whether or not a planning horizon exists. Some numerical examples are given.

ISSN:0160-5682    

DOI:10.1057/jors.1993.202

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

AbstractIn the classical transportation problem if the unit costs and transportation durations are considered, the time-cost trade-off solutions can be determined by the well-known threshold approach assuming that all the transportations are permitted to be simultaneous in time. If all the unit costs are linear functions of time over a specified interval of time, a parametric technique can be applied for identifying all the time-cost trade-off solutions pertaining to this interval. In this paper, the unit costs considered are piecewise linear non-increasing functions of time and transportations are allowed to be simultaneous. It is shown that a parametric method involving a finite sequence of parametric transportation problems reveals all the time-cost trade-off solutions of this generalized trade-off problem. Computational experience is included. If the transportation problem has considerable degeneracy, the parametric approach may pose some computational difficulty. This difficulty can be reduced by using an alternative method involving the bicriteria optimization approach of Aneja and Nair. Also, a direct method is outlined for the case where a finite set of discrete alternatives of unit cost-time pairs is available.

ISSN:0160-5682    

DOI:10.1057/jors.1993.203

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

ISSN:0160-5682    

DOI:10.1057/jors.1993.204

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor