Asia-Pacific Journal of Operational Research

We present a new admissible pivot method for linear programming that works with a sequence of improving primal feasible interior points and dual feasible interior points. This method is a practicable variant of the short admissible pivot sequence algorithm, which was suggested by Fukuda and Terlaky. Here, we also show that this method can be modified to terminate in finite pivot steps. Finally, we show that this method outperforms Terlaky's criss-cross method by computational experiments.

In this paper, we discuss why it is appropriate maximize the profits, instead of minimizing the costs, in an inventory system with an inventory-level-dependent demand rate. In addition, we restate Urban's viewpoint that the restriction of zero ending-inventory is not necessary in an inventory-level-dependent demand model. Consequently, we amend Giri and Chaudhuri's inventory model for deteriorating items by changing the objective to maximize the profits and relaxing the restriction of zero ending-inventory. Finally, we provide a couple of examples to show that both the order quantity and the profit obtained from our proposed model are significantly larger than those in Giri and Chaudhuri's model, in which the objective is to minimize the costs.

This paper presents a variant of Vogel's approximation method (VAM) for transportation problems. The importance of determining efficient solutions for large sized transportation problems is borne out by many practical problems in industries, the military, etc. With this motivation, a few variants of VAM incorporating the total opportunity cost (TOC) concept were investigated to obtain fast and efficient solutions. Computational experiments were carried out to evaluate these variants of VAM. The quality of solutions indicates that the basic version of the VAM coupled with total opportunity cost (called the VAM–TOC) yields a very efficient initial solution. In these experiments, on an average, about 20% of the time the VAM–TOC approach yielded the optimal solution and about 80% of the time it yielded a solution very close to optimal (0.5% loss of optimality). The CPU time required for the problem instances tested was very small (on an average, less than 10 s on a 200 MHz Pentium machine with 64 MB RAM).

Conceptual models are the critical first step to gaining distilled insights of complex systems. We use influence diagrams to link intuitive measures for Land Force actions with the inputs of the environment, and friendly and threat force actions. This approach provides a rich semiquantitative model that allows exploration of the effect of perturbation introduced through the adoption of enhanced equipment, innovative operational concepts, or novel technology concepts. We have built a construct for the Army based upon a set of influence diagrams for the skills of: engagement; information collection; sustainment; communication; protection; movement; and decision making. These produce mental maps that link military technologies, desired effects, and higher-level outcomes. Thus, there is a gradation of type within the influence diagram with position the key to the nature of the variable.

In this paper we describe these models and how we use them to deduce likely future military concepts through "what if" contemplations of possible technology or environmental changes. In reverse, this process advises on the criticality of the constituent components. Inter-relationships between various skills and issues associated with balancing requirements between these will be highlighted. This work thus leads to further distillation-like simulations such as agent-based modeling.

In this paper, a global optimization meta-heuristic, the great deluge algorithm, is extended and applied to optimize the reliability of complex systems. Two different kinds of optimization problems (i) Reliability optimization of a complex system with constraints on cost and weight (ii) Optimal redundancy allocation in a multi-stage mixed system with constraints on cost and weight are solved to demonstrate the effectiveness of the algorithm. A software developed in ANSI C, implements the algorithm. In terms of both accuracy and speed, it is observed that the present algorithm, the modified great deluge algorithm (MGDA) yielded far superior results compared to those obtained by the simulated annealing, the improved non-equilibrium simulated annealing and other optimization algorithms. Further, when both accuracy and speed are considered simultaneously, both MGDA and another meta-heuristic, ant colony optimization (ACO) yielded comparable results. In conclusion, the MGDA, can be used as an efficient alternative to ACO and other existing optimization techniques.

This study considers the effects of two real exchange rates on strategies that govern the locations of production by firms that are entering two foreign countries. The batch process production model of Lin and Wu (Asia-Pacific Journal of Operational Research, 21, 2004, 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 Analysis (ROA) to determine the value of locating production in three countries. Moreover, a closed-form solution to the Continuous-Time Model Optimization Problem is derived. The optimal entry trigger and expected arrival time of an exporter from country-0 to country-1 or 2 are calculated; a sensitivity analysis is performed, and some characteristic strategies of the operating method for the Cobb–Douglas batch process model among three countries are determined. A useful summary of insights is provided for global managers.

In this paper, the competition of dynamic oligopoly in the cruise line industry is modeled as an N-person nonzero-sum noncooperative dynamic game where a finite number of cruise lines compete to maximize their profits over a fixed planning horizon. The noncooperative Nash equilibrium capacity investment strategies of cruise lines are theoretically analyzed under the open-loop and closed-loop information structures. The optimality conditions for open-loop and closed-loop Nash equilibrium solutions are derived using a Pontryagin-type maximum principle and given economic interpretations so as to demonstrate the differences between the open-loop and closed-loop Nash equilibrium solutions. The dynamic oligopolistic competition of three cruise lines in a hypothetical setting is numerically analyzed by using the iterative algorithms for open-loop and closed-loop models. Numerical results provide a number of important managerial guidelines for cruise capacity investment decisions. The paper concludes with a discussion on future research directions.

This paper proposes the design and analysis of two metaheuristics, simulated annealing (SA) and tabu search (TS), for solving the feeder bus network design problem. The results are compared to those published in the literature. A comparative study is also carried out on several test problems generated at random to evaluate the performance of these heuristics in terms of their computational efficiency and solution quality. Computational experiments have shown that TS is a more effective metaheuristic in solving the problem than SA.