摘要:

AbstractOf key importance to oil and gas companies is the size distribution of fields in the areas that they are drilling. Recent arguments suggest that there are many more fields yet to be discovered in mature provinces than had previously been thought because the underlying distribution is monotonic not peaked. According to this view the peaked nature of the distribution for discovered fields reflects not the underlying distribution but the effect of economic truncation. This paper contributes to the discussion by analysing up-to-date exploration and discovery data for two mature provinces using the discovery-process model, based on sampling without replacement and implicitly including economic truncation effects. The maximum likelihood estimation involved generates a high-dimensional mixed-integer nonlinear optimization problem. A highly efficient solution strategy is tested, exploiting the separable structure and handling the integer constraints by treating the problem as a masked allocation problem in dynamic programming.

ISSN:0160-5682    

DOI:10.1057/jors.1996.187

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractData envelopment analysis (a mathematical programming technique) has often been applied to measuring the efficiency with which outputs are produced. The technique derives efficient combinations of outputs for given inputs: constant returns to size may be assumed or one may choose to examine whether decreasing or increasing returns hold true. An analysis of the cost of prescribing drugs for 106 general practices in the Lincolnshire Health Authority for the year 1993/1994 reveals the statistical problems that are encountered in applying this technique.

ISSN:0160-5682    

DOI:10.1057/jors.1996.188

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractSchool bus services within the UK are subsidised by the local Passenger Transport Executive and bus operators tender for the contracts, with the lowest price normally winning. Analysis of the bids in one district showed that the companies had pricing strategies, which could be estimated from freely available data when they were simple. The difficulties arose when competitors segmented the market.

ISSN:0160-5682    

DOI:10.1057/jors.1996.189

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractIn the Generalized Travelling Salesman Problem (GTSP), the aim is to determine a least cost Hamiltonian circuit or cycle through several clusters of vertices. It is shown that a wide variety of combinatorial optimization problems can be modelled as GTSPs. These problems include location-routeing problems, material flow system design, post-box collection, stochastic vehicle routeing and arc routeing.

ISSN:0160-5682    

DOI:10.1057/jors.1996.190

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractIn this paper, we use a 0–1 linear programming model for the machine assignment problem in cellular manufacturing. The formulated machine assignment problem considers many manufacturing factors such as machine utilization cost, cost of intercellular moves, part demand, and operating time capacity. The problem is shown to be NP-complete. Two designing algorithms are proposed to exploit the problem structure of the knapsack problem. Computational experience of the two algorithms is also reported.

ISSN:0160-5682    

DOI:10.1057/jors.1996.191

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractAutomated Guided Vehicle (AGV)-based material handling systems (MHS) are used widely in Flexible Manufacturing Systems (FMS). The problem of AGV consists of the decisions and the operational control strategies of dispatching, routeing and scheduling of a set of AGVs under given system environments and operational objectives. One remaining challenge is to develop effective methods of AGV decisions for improved system productivity. This paper describes a prototype neural network approach for the AGV problem in an FMS environment. A group of neural network models are proposed to perform dispatching and routeing tasks for the AGV under conditions of single or multiple vehicles, and with or without time windows. The goal is to satisfy the transport requests in the shortest time and in a non-conflicting manner, subject to the global manufacturing objectives. Based on Kohonen's self-organizing feature maps, we have developed efficient algorithms for the AGVs decisions, and simulation results have been very encouraging.

ISSN:0160-5682    

DOI:10.1057/jors.1996.192

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractCompetitive facility location models are based on the assumption that customers select a facility to patronize according to some rule involving the distance to the facility. A customer prefers facilityAover facilityBif the distance to facilityAis shorter than some function of the distance to facilityB. We define a consistency property of a selection rule. A selection rule is consistent if the selection of a facility remains unchanged along the shortest route to that facility: namely the rule cannot indicate a preference for a different facility whileen routeto the selected one. Otherwise, the rule is inconsistent. We prove that under mild conditions, the only consistent rule is the one based on an additive function of the distance, a function which is the sum of the distance and a constant. All other rules, such as a product of the distance and a constant (a multiplicative function), are inconsistent.

ISSN:0160-5682    

DOI:10.1057/jors.1996.193

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractWe consider the problem of sequencing picks in a set of orders on a single carousel. First we consider the situation in which the sequence of the orders is given. For this problem we present an efficient dynamic programming algorithm. Second, we consider the problem without a given order sequence. We simplify this problem to a Rural Postman Problem on a circle and solve this problem to optimality. Finally, we show that the solution of the Rural Postman Problem requires at most 1.5 revolutions more than a lower bound of an optimum solution to the original problem.

ISSN:0160-5682    

DOI:10.1057/jors.1996.194

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractWe propose a policy for controlling the release of raw wafers into semiconductor wafer fabrication lines. The proposed policy exploits up-to-date factory floor information gathered by tracking systems in order to calculate the timing and amount of new releases to minimize mean flow times and mean tardiness while maintaining the maximum output rates of the system. Extensive computer experiments show that the proposed policy results in at least 23.0 and 17.9% improvements on average in mean waiting time and mean tardiness respectively compared to existing release rules.

ISSN:0160-5682    

DOI:10.1057/jors.1996.195

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

AbstractThis paper sets out to solve the multi (more than two)-group classification problem, and develops a new linear programming model which simultaneously determines the cut-off values for the different classification functions. Instead of decomposing the content in the multi-group problem to facilitate computation of the cut-off values, this new model aggregates information contained in the multi-group problem which, intuitively, should provide better estimates of the group boundaries. Furthermore, this new model, one existing LP model, and a statistical approach will be tested by using real-life data.

ISSN:0160-5682    

DOI:10.1057/jors.1996.196

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor