Asia-Pacific Journal of Operational Research

In this paper a new formulation of the simple plant location problem (SPLP) is given that uses the style of Sharma and Sharma (European Journal of Operational Research, 122(3), 37–48). When the integer restrictions are relaxed, it results in a new relaxation of SPLP that is different from the already well known "strong" and "weak" relaxation of SPLP. It is shown that the bound given by the new relaxation is worse than the bound given by "strong relaxation" of SPLP. However, a numerical example illustrates that the bound given by the new relaxation can at times be better than the bound given by "weak relaxation" (already known) of SPLP. In this paper a new proof [which is different from the one given by Bilde and Krarup (Annals of Discrete Mathematics, 1, 79–97)] is given to establish relative strengths of various relaxations of SPLP.

In this paper we consider the location of stops along the edges of an already existing public transportation network. This can be the introduction of bus stops along some given bus routes, or of railway stations along the tracks in a railway network.

The positive effect of new stops is given by the better access of the potential customers to public transportation, while the travel time increases due to the additional stopping activities of the trains. The latter leads to a negative effect for the customers. The goal is to cover all given demand points with a minimal amount of additional traveling time, where covering may be defined with respect to an arbitrary norm or gauge. This problem is NP-hard, even in the special case of Euclidean distances. In this paper, we derive a finite candidate set leading to a discrete set covering problem. Moreover, we identify network structures in which the coefficient matrix of the resulting set covering problem is totally unimodular, such that the problem can be solved efficiently in this case. Extensions of the problem are also discussed.

This paper studies a two-crane scheduling problem in a port terminal. These two cranes are deployed in a block of a port terminal. They can move along a bi-directional traveling lane and must maintain a safe distance between them to avoid collision. A group of export containers in a block is required to be transported by cranes from their storage location to an access point of the block. Each container is associated with a due date. The problem is to find a schedule such that all containers are carried to the access point before their due dates. If such schedule does not exist, then the problem becomes to find schedules to minimize the maximum tardiness, the number of tardy jobs, respectively. In this paper, we first identify the necessary and sufficient conditions for the existence of a feasible schedule, i.e., a schedule transports all containers to the access point before their due dates and does not violate the requirement to maintain a safe distance between two cranes. We prove that if there exists at least one feasible schedule, then there must be a permutation schedule with containers sequenced in earliest due date (EDD) order to be feasible. An efficient algorithm is developed to find a feasible schedule given its existence. Furthermore, we provide efficient algorithms for minimizing the maximum tardiness, the number of tardy jobs, the makespan and the total completion time, respectively.

The considered problem in this paper is a 0-1 Multi-Quadratic Fractional Programming Problem (0-1MQFP) without the restriction of positive denominators. The two important contributions of the paper are: (a) it proposes a linearization technique to solve any type of 0-1MQFP problem; and (b) when applied to the 0-1MQFP problem with the restriction of positive denominators, it requires less number of constraints and variables as compare with the available techniques in the literature. The problem is proved to be NP-hard. The linearization process is summarized with the help of an algorithm and flow chart, and further illustrated by examples. Codes for linearizing 0-1MQFPP is given in the APPENDIX.

We study a MAP/M/c queueing system in which a group of servers take a simultaneous phase type vacation. The queueing model is studied as a QBD process. The steady-state analysis of the model including the waiting time distribution is presented. Interesting numerical results are discussed.

The Indian banking industry is going through turbulent times. With the lowering of entry barriers and blurring product lines of banks and non-banks since the financial sector reforms, banks are functioning increasingly under competitive pressures. Hence, it is imperative that banks maintain a loyal customer base. In order to achieve this and improve their market positions, many retail banks are directing their strategies towards increasing customer satisfaction and loyalty through improved service quality. Moreover, with the advent of international banking and innovations in the marketplace, customers are having greater and greater difficulty in selecting one institution from another.

Hence, to gain and sustain competitive advantages in the fast changing retail banking industry in India, it is crucial for banks to understand in-depth what customers perceive to be the key dimensions of service quality and to evaluate banks on these dimensions. This is because if service quality dimensions can be identified, service managers should be able to improve the delivery of customer perceived quality during the service process and have greater control over the overall outcome.

The study suggests that customers distinguish four dimensions of service quality in the case of the retail banking industry in India, namely, customer-orientedness, competence, tangibles and convenience. A methodological innovation in this study has been in the use of TOPSIS in the field of customer-perceived service quality. TOPSIS has been used to evaluate and ranking the relative performance of the banks across the service quality dimensions. Identifying the underlying dimensions of the service quality construct and evaluating the performance of the banks across these factors is the first step in the definition and hence provision of quality service in the Indian retail banking industry.

We study the coordination of supply chains with a risk-neutral supplier and a risk-averse retailer. Different from the downside risk setting, in a conditional value-at-risk (CVaR) framework, we show that the supply chain can be coordinated with the revenue-sharing, buy-back, two-part tariff and quantity flexibility contracts. Furthermore the revenue-sharing contracts are still equivalent to the buy-back contracts when the retail price is fixed. At the same time, it is shown that the risk-averse retailer of the coordinated supply chain can increase its profit by raising its risk-averse degree under mild conditions.