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The practice of queuing is a daily experience for most of us and it is usually difficult to combine it with other activities. This indicates that people involved in the act of queuing become a bit too occupied with maintaining one's position in the queue. Despite that queuing is a common phenomenon, queuing situations are now often equipped with aids based on numbers that help regulating the queuing order. Still, the practice of queuing includes several nuances of social interaction that demands careful attention from its participants for it to work. Based on cases and concepts with varying levels of viability, this thesis investigates the practice of queuing as a design space. The thesis further suggests how a more flexible queue could be designed. An overall aim is to examine how to provide greater action space for participants in a queue and enable for new forms of interaction. In order to queue from a distance, much of what traditionally constructs the queue is redesigned. To address these issues from a usability point of view, it is a challenge to create an interaction design that allows different ways of queuing, without deviating too much from features that are evaluated as decisive to maintain.

Multiclass queueing networks are widely used to model complex manufacturing systems and communications networks. In this dissertation we describe and analyze a multiclass queueing network model known as the Cambridge Ring. As the name suggest this network has a circular topology with unidirectional routing. In many cases the analysis of a stochastic model is a difficult task. For a few special cases of this network we show that all non-idling policies are throughput optimal for this system. One of the major differences between this work and precious literature is that we prove throughput optimality of all non-idling policies, whereas most of the previous work has been on establishing throughput optimality for a specific policy (usually First-In-First-Out). We use a macroscopic technique known as fluid model to identify optimal policies with respect to work in process. In one case we consider, the discrete scheduling policy motivated by the optimal fluid policy is indeed optimal in the discrete network. For the other special case we show by means of a deterministic counterexample that the discrete policy most naturally suggested by the fluid optimal policy may not be optimal for the queueing network. We also formulate the fluid holding cost optimization problem and present its solution for a simple version of the Cambridge Ring. Further we establish that the optimal policy under a class of policies known as "non-ejective" policies may be an idling policy. We use an example of the Cambridge Ring with a single vehicle to show that the optimal policy for this example has to be an idling policy. / text

We examine the problem of staffing refreshment stations at a long distance road race. A race is modeled as a mixed queueing network in which the required number of servers at each service station has to be estimated. Two models to represent the progress of runners along a long distance road race course are developed. One model is a single-class model that allows a road race manager to staff service stations assuming the runners are identical to those in some historical dataset. Another model is a multi-class simulation model that allows a road race manager to simulate a race of any number of runners, classified based on their running pace into different runner classes. Both the single-class model and the multi-class model include estimates for the rates at which the runners arrive at specified locations along the course. The arrival rates, combined with assumed service rates, allow us to base staffing decisions on the Erlang loss formula or a lesser known staffing rule that gives a lower bound for the required number of servers. We develop a staffing strategy that we call the Peak Arrival Staffing Bound (PASB), which is based on this staffing bound. The PASB and the Erlang loss formula are implemented in the single-class model and the multi-class simulation model. By way of numerical experiments, we find that the PASB is numerically stable and can be used to get staffing results regardless of the traffic intensity. This finding is in contrast to the Erlang loss formula, which is known to become numerically unstable and overflows when the traffic intensity exceeds 171. We compare numerical results of the PASB and the Erlang loss formula with a blocking probability level of 5% and find that when iii the traffic intensity is high, staffing results based on the PASB are more conservative than staffing results based on the Erlang loss formula. As the traffic intensity gets lower, we find that staffing results based on the PASB are similar to staffing results based on the Erlang loss formula. These findings suggest that the PASB can be a valuable tool to aid race directors in making staffing decisions for races of all traffic intensities

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Alfred P. Sloan School of Management, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY. / Bibliography: leaves 199-201. / by Emily Jane Roth. / Ph.D.

Bibliography: leaves 147-152.

The objective of many steady-state simulations is to study the behavior of a nonterminating system with a peak load of infinite duration. Due to the complexity of the system, the initial conditions of the system are often atypical that often requires the simulators to start the system with the empty and idle conditions. Consequently, deletion of some initial observations is required to reduce the initialization bias induced by atypical initial conditions. This paper studies the application of Schriber's truncation rule to the complex queueing systems (specifically, the two-machine and three-machine tandem queueing system) and the effects of parameter selection (i.e. parameters batch size and time between observations) on performance measures. Based on the previous studies of Schriber's rule on the one-machine system, parameters batch count and tolerance are held constant. Mean-squared error and half length are used as measures of accuracy and interval precision in comparing the results. The results of both systems show that time between observations and batch size are significant parameters, and the recommendations for the two-machine system can be generalized for the three-machine system. Increasing the number of machines in the system from two to three requires a careful reduction in the value of time between observations. Besides, multiple replications should be used to minimize the extreme results in determining the steady-state mean number of entities and the truncation point. / Graduation date: 1992

In wired network, there are many researches about scheduling algorithm. As for wireless network, the scheduling algorithm is not maturer than wired network. And there are some following characteristics of wireless network that we can not make use of wired scheduling algorithm directly:(1)Less bandwidth in wireless network;(2)Location dependent errors;(3)Higher error rate and bursty error. So when we design the wireless scheduling algorithm, there are some important issues we should take into account¡G (1)Fairness ; (2)QOS ; (3)Whether the overall throughput rises or not; (4)Whether the bandwidth is best utilized or not In this paper, we introduce the wired and wireless scheduling algorithm separately and discuss the advantage and disadvantage of these methods first. And we propose a scheduling algorithm which is based on WFQ [1] and dynamically adjusts weights according to the error rate of each flow. In this method, the base station will allocate the bandwidth by calculating the weight of mobile hosts and the proportion of error rates to the whole body. And during the process of adjusting, we will prevent the weight of a certain channel from increasing or decreasing excessively which might lead to unfair phenomenon. Under this adjustment, we will raise the whole throughput and maintain the fairness of all users.

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