Centralizing and using proper transportation facilities cut down costs and traffic. Hub facilities concentrate on flows to cause economic advantage of scale and multimodal transportation helps use the advantage of another transporter. A distinctive feature of this paper is proposing a new mathematical formulation for a three-stage p-hub location routing problem with simultaneous pick-ups and de...

because of high speed, efficiency, robustness and flexibility of multi-agent systems, in recent years there has been an increasing interest in the art of these systems. in competitive multi agent systems, a mechanism is required via which the agents can come to reach an agreement.  contract net protocols are one of the well-known negotiation protocols in multi-agent systems. in contract net pro...

The applications based on cloud computing platform usually need to use a number of computing resources and storage resources to completing computing tasks, so the faulttolerant capability of system has become increasingly important. Aiming to solve this problem, an evaluation model of task scheduling is proposed based on cloud system (TSCS). TSCS can effectively model and simulate complex cloud...

The following analytical approaches: queuing network models, stochastic automata networks, stochastic timed Petri nets, stochastic process algebra, Markov chains can be used in performance evaluation of multi–agent systems. In this paper, new approach which is based on PERT networks is presented. This approach is applied in performance evaluation of layered multi–agent system. Time-out mechanis...

Switch-based interconnects are used in a number of application domains including parallel system interconnects, local area networks, and wide area networks. However, very few switches have been designed that are suitable for more than one of these application domains. Such a switch must offer both extremely low latency and very high throughput for a variety of different message sizes. While som...

Mean waiting time is of a greater concern wherever queuing system is involved. Priority Scheduling is the general method used to reduce the mean waiting time of higher priority processes. However this method just focuses on favouring higher priority processes leaving the lower priority processes out of consideration and forcing them to starve for a longer period resulting in higher average mean...

In many logistic systems for less than truckload (LTL) shipments, transportation of goods from one origin to its destination is made through collection tours to a hub and delivery tours from the same or another hub, while the goods are shipped between two hubs using Full Truckload (FTL) shipments. Therefore, managers need to determine the location of the hubs, the allocation of non-hub nodes, a...

We consider queuing systems as models of distance learning system we analyze how characteristics of business process in the system affect on throughput and on learning outcomes. The processes of executing tasks and tasks validation process are the key processes in the distance learning. A model of the process performed by a student is a queuing system with refusals. A model of the process perfo...

In this study we present straightforward optimization methods to address two problems associated with designing large scale ambulance operations on highways; the question of location and the issue of districting. Previous approaches tackled small scale problem instances using exact hypercube queuing models integrated into optimization procedures mainly due to excessive computer storage and runt...