This paper deals with a delayed ratio-dependent functional response predator-prey model with a threshold harvesting policy. We study the equilibria of the system before and after the threshold. We show that the threshold harvesting can improve the undesirable behavior such as nonexistence of interior equilibria. The global analysis of the model as well as boundedness and permanence properties a...

In this paper, we consider a newsvendor who is going to invest on dedicated or flexible capacity, our goal is to find the optimal investment policy to maximize total profit while the newsvendor faces uncertainty in lead time and demand simultaneously. As highlighted in literature, demand is stochastic, while lead time is constant. However, in reality lead time uncertainty decreases newsvendor's...

Under cutoff and threshold priority policies, we mathematically formulate a prioritized channel allocation problem which is combinatorial in nature. We then reduce that problem using the concept of pattern, and apply a simulated annealing approach to the reduced problem. Computational experiments show that our method works very well and the cutoff priority policy outperforms the non-prioritized...

We consider a set of n heterogeneous servers which differ in processing time and Quality of Service (QoS). Jobs are divided into m levels with regard to their service ranks. We present a Threshold Policy (TP) depending on number of different jobs in the queues as a practical and flexible dynamic routing policy to control the QoS. Two performance measures are discussed: the QoS and the Average W...

In this paper we analyze a controlled retrial queue with several exponential heterogeneous servers in which the time between two successive repeated attempts is independent of the number of customers applying for the service. The customers upon arrival are queued in the orbit or enters service area according to the control policy. This system is analyzed as controlled quasi-birth-and-death (QBD...

We consider a heterogeneous two-server system processing fixed size jobs. This includes the scheduling system, where jobs wait in a common queue, and the dispatching system, where jobs are assigned to server-specific queues upon arrival. The optimal policy with respect to the delay in both systems is a threshold policy characterized by a single parameter. In this special case, the scheduling an...

Background: Acupuncture is an indispensable part of traditional Chinese medicine for relief of pain. The purpose of this study was the immediate & latent of low power LASER Ga-Al-As irradiation applied to acupuncture points on experimental pain threshold. Methods: This quasi-experimental study was conducted on seventy adult women ranging from 20 to 40 years old assigned randomly into two groups...