Huei-Mei Liang

Monotonicity properties of single-server retrial queues

A single server retrial queue is a queueing system consisting of a primary queue with finite capacity, an orbit and a server. Customers can arrive at the primary queue either from outside the system or from the orbit. If the primary queue is full, an arriving customer joins the orbit and conducts a retrial later. Otherwise, he enters the primary queue, waits for service and then leaves the system after service completion. We investigate the effect of retrial times on the behavior of the system. In particular, we assume that the retrial time distributions are phase type and introduce a new relation, which we call K-dominance (short for Kalmykov), on these distributions. Longer retrial times with respect to this K-dominance are shown to result in a more congested system in the stochastic sense. From these results, we derive monotonicity properties of several system performance measures of interest.

Stability condition for a single-server retrial queue

A single-server retrial queue consists of a primary queue, an orbit and a single server. Assume the primary queue capacity is 1 and the orbit capacity is infinite. Customers can arrive at the primary queue either from outside the system or from the orbit. If the server is busy, the arriving customer joins the orbit and conducts a retrial later. Otherwise, he receives service and leaves the system. We investigate the stability condition for a single-server retrial queue. Let A be the arrival rate and 1/p be the mean service time. It has been proved that A/p <1 is a sufficient stability condition for the M/G/1/1 retrial queue with exponential retrial times. We give a counterexample to show that this stability condition is not valid for general single-server retrial queues. Next we show that A/M < 1 is a sufficient stability condition for the stability of a single-server retrial queue when the interarrival times and retrial times are finite mixtures of Erlangs.

The effects of absorptive capacity, knowledge sourcing strategy, and alliance forms on firm performance

This paper explores the relationship between absorptive capacity, knowledge sourcing strategy, alliance forms, and firm performance. Based on the literature, the concept of a knowledge sourcing strategy in alliance contexts is proposed, which can be categorised into two types: a knowledge internalisation strategy and a knowledge access strategy. From an organisational learning perspective, it is argued that a firms absorptive capacity has a positive influence on a knowledge internalisation strategy, and accordingly a firms choices of alliance forms are also influenced. R&D performance is also included in the theoretical model in order to generate further managerial implications. Instead of using conventional regression methods, structural equation modelling (SEM) is adopted to conduct path analysis, as SEM is well suited in verifying multiple-dependent models. The arguments advanced are supported by empirical analysis of a sample of 148 alliances.

Optimal Routing Control in Retrial Queues

Dedication. One of the earliest papers in retrial queues is by Keilson, Cozzolino, and Young [6]. Retrials queues has grown into an important area of research over the last decade, as evidenced by the survey papers by Yang and Templeton [11], Falin [3], and Kulkarni and Liang [7]. However, as far as the authors are aware, there are no results on the control of retrial queues. In this chapter, we try to fill this gap.

The long-run uncovered interest rate parity in view of a trading strategy

Uncovered Interest Rate Parity (UIP) states that bonds in different denomination should produce the same returns if the maturities of the bonds are the same. Given this, if a foreign bond produces a lower holding period return than a home bond of the same maturity, for their remaining lives the same foreign bond ought to produce a return higher than the home bond. A test is designed according to this relationship. With 1 to 6 year interest rate data of U.S., Britain and Germany from 1979 to 2005, our test shows that this relationship is more reliable for 6-year interest rates than the shorter rates in general. This result lends support to the long-run UIP. A trading strategy is developed by utilizing this idea. We show that positive returns can be achieved by the strategy for bonds of longer horizons. This result also serves as indirect evidence of the long-run UIP.