 Customer impatience (reneging) has negative impact on the performance of queueing systems. If we talk from business point of view, firms lose their potential customers due to customer impatience which affects their business as a whole. It is envisaged that if the firms employ certain customer retention strategies then there are chances that a certain fraction of impatient customers can be ret...

Motivated by the dispatching of trucks to shovels in surface mines, we study optimal routing in a Markovian finite-source, multi-server queueing system with heterogeneous servers, each with a separate queue. We formulate the problem of routing customers to servers to maximize the system throughput as a Markov Decision Process. When the servers are homogenous, we demonstrate that the Shortest Qu...

Response times in large distributed systems can be reduced by exchanging jobs between idle servers and servers with pending jobs. When a pull strategy is deployed the initiative to exchange jobs is taken by the idle servers, while servers with pending jobs initiate the exchange when a push strategy is implemented. In this paper the performance of a class of rate-based pull and push strategies f...

We study an M/M/2 queueing system with two heterogeneous servers under a variant vacation policy, where the two servers may take together at most J vacations when the system is empty. A quasi-birth-and-death process is formulated to analyze the system. We obtain the explicit expressions of the stationary distribution of the system size and the mean system size. We also show that the number of v...

Nowadays energy consumption problem is a major issue for data centers. The energy consumption increases significantly along with its CPU frequency getting higher. With Dynamic Voltage and Frequency Scaling (DVFS) techniques, CPU could be set to a suitable working frequency during the running time according to the workload. On the other side, reducing frequency implies that more servers will be ...

Heterogeneous wireless networks are capable of providing customers with better services while service providers can offer more applications to more customers with lower costs. To provide services, some applications rely on existing servers in the network. In a vehicular ad-hoc network (VANET) some mobile nodes may function as servers. Due to high mobility of nodes and short lifetime of links, s...

In this paper, we study the following theoretical scheduling problem: the tasks of a given application have to be statically distributed and executed on the heterogeneous servers of a multi-user system on a wide area, heterogeneous network, such as Internet. The application is divided into a set of communicating tasks that may be executed on at least one, and possibly several, servers. The proc...