摘要:

AbstractDespite many advances in biotechnology being futuristic, in some industries such technological improvements are now becoming generally available for absorption into commercial practice. The new reproductive technologies for bovine animals are such an example. For a regulated industry like agriculture, an ex ante evaluation of the impact of their adoption is the concern of policy makers. This paper describes a modelling strategy devised to assess these impacts, using a sequence of stochastic, financial and linear programming models. A set of individual farm type models were developed and later extended to a national model to simulate the interactions that occur between dairy and beef enterprises and the competition between them for resources on individual farms. Restraints reflecting national policies such as quotas on milk production and industry support through subsidies are built into the model to explore several scenarios. These models are used to assess the impact of new technologies on dairy and beef production nationally and for regions which have been identified by the Ministry of Agriculture, Fisheries and Food.

ISSN:0160-5682    

DOI:10.1057/jors.1996.169

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractAn increasingly common feature of manufacturing companies is the use of robotic component placement machines in the assembly of electrical goods. These machines place electronic components at predefined positions on printed circuit boards. A robotic arm, which carries one component at a time, collects components from feeders and places them, under computer control, onto the printed circuit board.Using examples provided by a major New Zealand manufacturer, we investigated the problem of assigning component reels to feeder positions and then constructing efficient placement sequences for such a robotic placement machine. An integer programming formulation is developed for this problem that, unlike previous solution techniques in the literature, can produce solutions which provably minimize total placement time for all company supplied sample problems. This solution method generates solutions approximately 10% better than those generated manually by the manufacturer's engineers.

ISSN:0160-5682    

DOI:10.1057/jors.1996.170

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractIn this paper, a number of non-regular bicriteria penalty functions of completion times on a single machine are studied. In each function, one criterion is a measure of central tendency (CT) of completion times, for example, mean or median, and the other is a measure of completion time dispersion (DSP). Five different DSP measures are considered in the paper. We discuss the characterizations of optimal sequences for some new functions and summarize previous results when appropriate for the pure bicriteria problem as well as for the convex combination of CT and DSP. Further, in the context of minimizing a dispersion measure, a comparison is made between the two dispersion measures of variance of completion times and total absolute deviations of completion times (TADC).

ISSN:0160-5682    

DOI:10.1057/jors.1996.171

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractRepair limit analysis was originally proposed as a methodology for determining whether to repair or to replace an operating unit. The approach structures the problem as a Markov or semi-Markov decision process in which state-dependent repair limits trigger the replacement decision. Such a basic framework can easily be applied to more general equipment repair/overhaul environments in which typical maintenance condition monitoring information can serve as the overhaul trigger. One unnecessary limitation of repair limit analysis found in the literature is the use of a constant force of mortality within each state of the model. The purpose of this paper is to extend the repair limit analysis by incorporating a changing force of mortality as the unit ages. In this way, the analysis is more flexible in the parameter estimation phase and it is argued here more appealing since a changing (and usually increasing) force of mortality is utilized in equipment maintenance environments.

ISSN:0160-5682    

DOI:10.1057/jors.1996.172

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractA surrogate for an investor's bi-criteria utility function (profitability, safety) is proposed as an alternative methodology for selecting portfolios. The optimum is approximated by resorting to a recent utility theorem expounded in multi-criteria analysis. This method is developed for an‘average’investor and could be used as a routine procedure by investment consultants with incomplete information of the client's utility function.

ISSN:0160-5682    

DOI:10.1057/jors.1996.173

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractA method is developed here for characterizing the empirical distribution of the efficient units in data envelopment analysis. Two empirical applications illustrate the various uses of the distribution approach. One involves the cost frontier which exhibits increasing returns to scale and the other involves a dynamic production frontier, where technological change causes a shift of the production frontier over time.

ISSN:0160-5682    

DOI:10.1057/jors.1996.174

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractA generalized EOQ model for deteriorating items is considered here in which the demand rate, deterioration rate, holding cost and ordering cost are all assumed to be continuous functions of time. Shortages are also allowed and are completely backlogged. The planning horizon is finite and the replenishment periods are assumed to be constant. The optimal replenishment policy and the decision rule which minimizes the total system cost are derived. A numerical example is given to illustrate the developed model. Sensitivity analysis is also presented for the given model.

ISSN:0160-5682    

DOI:10.1057/jors.1996.175

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractA component has time to failureXwith densityf(·). Opportunities arise as a Poisson process of rateλ. At an opportunity the component may at choice, be replaced at costc2. At failure the components can either be minimally repaired at costc1or replaced at costc4. Finally the component may be replaced at any time at an‘interrupt’cost ofc3. We derive expressions for the long-run expected cost rate, and give examples of numerical optimisation with respect to control limits on age at an opportunity, and at an interrupt replacement.

ISSN:0160-5682    

DOI:10.1057/jors.1996.176

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractThis note establishes a connection between two problems that appear in different contexts: the Product Rate Variation (PRV) problem (sequencing units in a mixed-model assembly line in order to maximize the regularity of the sequence with regard to the output of units) and the apportionment problem. This allows us to apply to the PRV problem the properties of the apportionment problem and known procedures for solving it, and suggests alternative approaches to the former problem.

ISSN:0160-5682    

DOI:10.1057/jors.1996.177

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractThis paper is concerned with the use of incomplete information about utilities and weights in multiattribute decisionmaking. Because of time pressure and/or lack of knowledge, a decision maker may only be able to provide incomplete information which might be expressed as a set of linear inequalities. If the decision maker's information on both weights and utilities is imprecisely identified, then the model for establishing pairwise dominance becomes a non-linear program. A method for obtaining non-dominated alternatives without solving the non-linear program is proposed using a simple weighted-additive function.

ISSN:0160-5682    

DOI:10.1057/jors.1996.178

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor