Asia-Pacific Journal of Operational Research

We describe an exercise in trying to adjust faculty salaries at a national university in the Arabian Gulf region in order to attract and retain quality faculty. The problem is strongly constrained by policy and budget considerations and leads to two loosely related sub-problems: market adjustment and merit adjustment, which are to be achieved by means of specially sanctioned funds and available discretionary funds, respectively. We propose a methodology that addresses the former through goal programming and the latter through data envelopment analysis. We illustrate, with a small set of real data, how this approach works.

This study considers the effects of one real exchange rate on strategies that govern locations of production by firms that are entering N - 1 foreign countries. The batch process production model (Lin, CT and CR Wu (2004a). Asia Pacific Journal of Operational Research, 21, 35–52) which considers two locations of production, one in each of two countries is extended to develop a decision valuation model to choose the two optimal locations to produce a good — one in each country. This extended model applies the real options approach (ROA) to determine the value of locating production in N countries. Moreover, a closed-form solution to the Continuous-Time Model Optimization Problem is derived. The optimal entry threshold value of a firm from country-0 to country-(N - 1) is calculated; a sensitivity analysis is performed, and some characteristic strategies of the operating method for the Constant Elasticity of Substitution (CES) batch process model among N countries are determined. Next, we can get optimal entry threshold value for Cobb-Douglas, perfect substitution and Leontief by CES production function. A useful summary of insights is provided for global managers.

This paper considers a batch scheduling problem in a two-stage hybrid flowshop that consists of m dedicated parallel machines in stage 1 and a batch processor in stage 2. The processing time of a batch is defined as the largest processing time of the jobs contained in that batch. The criterion is to minimize the makespan, the time by which all operations of jobs have been processed. For such a problem, we present a polynomial time algorithm for the case with all jobs having the same processing time on the batch processor. An approximation algorithm with a competitive ratio 2 for the general case is also presented.

In this work we introduce a new maintenance policy called the delayed repair policy. For delayed repair models, repair facilities are not always available. If the repair facilities are not available and a failure of the system occurs, the repair is delayed until the repair facilities are available again. In this work, we suppose that the repair facilities are available only during a time interval of the working period. We study this maintenance policy under the designation type I delayed repair policy. We analyze this strategy repair and we obtain bounds for the optimal type I delayed repair policy.

The main aim of this paper is to generalize the notion of pseudolinearity to nondifferentiable functions and to obtain characterizations for such functions. Under the assumption of pseudolinearity, a characterization for the solution sets of an optimization problem and a variational inequality problem has been obtained.

An inventory model is discussed with generalized ramp-type demand where the time to deterioration follows Weibull distribution. Shortages of inventories are allowed and completely backlogged. Total cost is derived by trading off setup cost, holding cost, deterioration cost, and shortage cost. The optimal replenishment policy for a single period is derived by minimizing the total cost per unit time over infinite time horizon. A numerical example is presented and sensitivity analysis is also carried out. The rationale for generalized ramp-type demand is discussed.

This paper considers a periodic preventive maintenance policy under which each preventive maintenance (PM) reduces the hazard rate of the repairable system, while keeping the pattern of hazard rate unchanged. For this model, the hazard rate at a given time t is affected by the improvement factor which depends on the number of PMs conducted until t. In addition to the periodic preventive maintenance, the system undergoes the minimal repair at each failure between the preventive maintenances. We derive mathematical formulas to evaluate the expected cost rate per unit time by computing the expected number of failures depending on the hazard rate of the underlying life distribution of the system. Assuming that the system is replaced by a new one at the N-th preventive maintenance, the optimal values of N and the preventive maintenance period, which minimize the expected cost rate, are solved and thus the best schedules for the periodic preventive maintenance policy are established. Explicit solutions for the optimal schedule for the periodic preventive maintenance are presented when the failure times follow the Weibull distribution.

This study develops an integrated deteriorating inventory policy for a single-buyer–single-supplier model with multiple JIT deliveries considering the transportation cost, inspection cost and the cost of less flexibility. Distinct from the former concept of average inventory level, our paper proposes a significantly different approach to deal with the first production batch and uses a revised method to approximate the relationship between the supplier's production time and the storage time. We provide a rigorous analysis to derive the number of inspection and deliveries, the optimal cycle time of deliveries, and the delivery size for the replenishment policy of the integrated buyer–supplier inventory deteriorating model. It is shown that the unit inspection cost is one of the critical factors affecting the deteriorating inventory model. A numerical example is presented to illustrate the theory.