摘要:

AbstractQuality improvement continues to be a major concern for many companies despite (and no doubt because of) recent adverse trading conditions. Yet it often takes place without a full formal evaluation of the possible expenditures involved. Computer simulation offers an attractive means of rectifying this common oversight. Experience at a complex manufacturing facility confirms the power of the technique for costing out rival quality procedures and controls.

ISSN:0160-5682    

DOI:10.1057/jors.1995.97

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractA major shipping company in Hong Kong is faced with several logistical and allocation problems. It needs to find a better way to allocate empty containers that are transported from the Middle East to ports in the Far East, subject to vessel schedules and capacities. It needs to know what to do when the supply of empty containers is less than the demand, and it needs to determine the mix of container types that the company should maintain in the long run. To deal with these challenges, a simulation model of the shipping company's operational activities was developed. Heuristic search was employed to identify the policies that yield the lowest operating cost in terms of leasing, storage, pick-up, drop-off and other charges. What makes the problem difficult is that the forecasts of future export movement as well as the demand for empty containers change continually and the company is faced with the possibility of lost sales if containers are not available when requested by customers. This study provided insights that resulted in substantial savings to the shipping company while increasing customers' satisfaction.

ISSN:0160-5682    

DOI:10.1057/jors.1995.98

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractA problem put forward recently by a Regional Water Authority differs from the well-known Capacitated Warehouse Location Problem only in that there are both weeks of normal demand levels and weeks of peak demand levels. We describe how Lagrangian relaxation based branch-and-bound algorithms have been adapted for the new problem. Computational results are given, enabling a comparison of the different approaches tried.

ISSN:0160-5682    

DOI:10.1057/jors.1995.99

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractTransport pricing at the level of the firm is addressed. The numbers of full fare passengers travelling on three routes of two competing bus companies are analysed using a multiplicative discontinuous price model. Results show that generally only the operator increasing the price suffers a loss of passengers and the price elasticity is a non-linear function of the resulting price difference. The method of analysis and the results have implications for the market modelling of fast moving consumer goods. It is noted that almost no studies of transport pricing at the level of the firm have been carried out previously because of lack of data.

ISSN:0160-5682    

DOI:10.1057/jors.1995.100

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThis paper investigates the problem of allocating office space to members of staff in an academic institution. We identify several conflicting objectives and formulate an integer pre-emptive goal programming model to address them. Using data from a pilot site of the University of Westminster, UK, we then experiment with alternative rankings of the objectives. Finally, given the plans to consolidate the activities of this university into fewer sites and the resulting need to relocate some staff members, we discuss how this model can be used to ensure that this process is carried out with the least possible inconvenience.

ISSN:0160-5682    

DOI:10.1057/jors.1995.101

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractIn this paper, we present a branch-and-bound approach for solving a two-machine flow shop scheduling problem, in which the objective is to minimize a weighted combination of job flowtime and schedule makespan. Experimental results show that the algorithm works very well for certain special cases and moderately well for others. In fact, it is able to produce optimal schedules for 500-job problems in which the second machine dominates the first machine. It is also shown that the algorithm developed to provide an upper bound for the branch-and-bound is optimal when processing times for jobs are the same on both machines. The primary reason for developing the branch-and-bound approach is that its results can be used to guide other heuristic techniques, such as simulated annealing, tabu search and genetic algorithms, in their search for optimal solutions for larger problems.

ISSN:0160-5682    

DOI:10.1057/jors.1995.102

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThis paper considers two basic location problems—the Weber problem and the minimax problem-on a regular grid of alternating one-way routes or streets. Both the facility to be located and the demand points are restricted to any point on the network. The one-way restriction is often used for efficiency in traffic flow, but complicates the distances in the system.

ISSN:0160-5682    

DOI:10.1057/jors.1995.103

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractWe develop an exact closed-form expression for the steady-state availability of a repairable,N-server system in which the ith server containsniidentical, reconfigurable, breakdown-prone units. Our approach, which follows from the Markov chain balance equations and the recursive properties of Hessenberg matrix determinants, is simpler than previously proposed matrix geometric approaches, and can readily be adapted to the availability analysis of more complicated structures. We illustrate this by computing the steady-state availability of a mixed parallel-serial gracefully degrading replicated system.

ISSN:0160-5682    

DOI:10.1057/jors.1995.104

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThis paper deals with schedulingnjobs on a single machine in order to minimize the weighted sum of squared waiting times of the jobs. We present a powerful decomposition mechanism, based on a precedence relation concept, that easily handles problems of the sizen= 50 and 100 where the processing times and penalties are independently drawn from a uniform distribution. This mechanism is incorporated along with new branching rules in a branch-and-bound scheme that efficiently handles tough problems of the size 20 and 50.

ISSN:0160-5682    

DOI:10.1057/jors.1995.105

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractThe optimal due date determination and sequencing problem ofnjobs, on a single machine, with deterministic processing times is reviewed. An algorithm, using the SLK method, has been previously described by the authors, by means of which one optimal sequence as well as all the alternative optima are determined without resorting to the Complementary Pair and Exchange Principle concepts. In this paper, a similar algorithm using the CON method is proposed, the optimization criterion being the minimization of the total lateness penalty. It is shown that both algorithms lead to the same minimum value of the objective function. It is also shown that all the alternative optima of either method may be determined, if those optima derived from the other method are known.

ISSN:0160-5682    

DOI:10.1057/jors.1995.106

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor