Asia-Pacific Journal of Operational Research

The paper presents a priority algorithm for the maximum lateness problem with parallel identical processors, precedence constraints, and preemptions. The presented algorithm calculates the priority of each task by constructing a schedule for the set of its successors. The algorithm is motivated by comparison of its nonpreemptive counterpart with other algorithms for the problem with unit execution time tasks. It is shown that the presented algorithm constructs an optimal schedule for the problem with two processors and arbitrary precedence constraints, and for the problem with an arbitrary number of processors and precedence constraints in the form of an in-tree. This proof also indicates that the presented algorithm allows the worst-case performance ratio previously established for the so-called Muntz–Coffman algorithm for a particular case of the considered problem where all due dates are zero.

We study properties of a modified memory gradient method, including the global convergence and rate of convergence. Numerical results show that modified memory gradient methods are effective in solving large-scale minimization problems.

Deterioration is defined as decay, damage, spoilage, evaporation, obsolescence, pilferage, and loss of utility or loss of marginal value of a commodity that reduces usefulness from original ones. Blood, fish, fruits and vegetables, alcohol, gasoline, radioactive chemicals, medicines, etc., lose their utility with respect to time. In this case, a discount price policy is implemented by the suppliers of these products to promote sales. In this study, a mathematical model is developed for an inventory system that considers a temporary price discount when commodities in an inventory system are subject to deterioration with respect to time. Our goal in this article is to maximize the difference between two costs (gain) — taking advantage of price discount by ordering a large quantity, which in turn increases inventory holding cost as well deterioration cost and by not ordering a large quantity at a discounted price. An attempt is made to find bounds on the beneficial discount rate. The model is supported with a numerical example.

The purpose of this paper is threefold: to assess the performance of 55 international tourist hotels in Taiwan in 2001 in terms of managerial, occupancy, and catering efficiencies; to analyze hotel operating characteristics, which might explain the variation in managerial efficiencies across these hotels; and to measure productivity growth in the 34 international tourist hotels over the years 1990–2001. Empirical results indicate that (1) the marketing for lodging services was not operated efficiently in 2001; (2) the hotels operated poorly both at the levels of occupancy and catering efficiencies in 2001; (3) there is a weak tendency for a hotel with relative high catering efficiency to go with good occupancy efficiency; (4) differences in operating variables, such as the floor space of catering department, the number of guest rooms, the closeness of a hotel to CKS international airport, and the number of employees do have a significant influence upon hotel performance; and finally, (5) about 61.76% of hotels had annual productivity changes over time.

A standard mixed integer programming (MIP) approach is compared with a two-stage MIP approach. A computational difference between the two DA (discriminant analysis) approaches is that the former uses a single MIP model to solve various classification problems and the latter uses two MIP models that classify all observations into one of two groups or an overlap at the first stage and then reclassify the overlapped observations at the second stage. In this study, the two MIP approaches are methodologically compared and then applied to a published data set related to Japanese banks. These classification performances are assessed by four hit rates. Based upon the comparison, it is confirmed that the two-stage approach performs at least as well as the standard approach.

The shortest-residual family of conjugate gradient methods was first proposed by Hestenes and was studied by Pytlak, and Dai and Yuan. Recently, a no-line-search scheme in conjugate gradient methods was given by Sun and Zhang, and Chen and Sun. In this paper, we show the global convergence of two shortest-residual conjugate gradient methods (FRSR and PRPSR) without line search. In addition, computational results are presented to show that the methods with line search have similar numerical behavior to the methods without line search.

This paper proposes a nonlinear goal programming technique for obtaining economic order quantity of multi-item inventory problems. In the decision-making context, penalty functions are incorporated in the goal programming formulation. The proposed technique has been demonstrated via a case study.

The main purpose of this paper is to study the reliability and availability of a system with M operating devices, m spares, and an imperfect service station that takes vacations. Specifically, once there are no failed devices in the system, the service station takes consecutive vacations until there is at least one failed device upon its return from vacation. The service station may break down and require repair at a repair facility. This paper derives the reliability, the mean time to system failure, the availability, and failure frequency of the K-out-of-M + m system. Numerical simulation of the impacts of system parameters as well as sensitivity analysis for the reliability, the mean time to system failure, the availability and failure frequency is performed.