Anthony Bedford

Waiting time analysis of the multiple priority dual queue with a preemptive priority service discipline

The dual queue consists of two queues, called the primary queue and the secondary queue. There is a single server in the primary queue but the secondary queue has no service facility and only serves as a holding queue for the overloaded primary queue. The dual queue has the additional feature of a priority scheme to help reduce congestion. Two classes of customers, class 1 and 2, arrive to the dual queue as two independent Poisson processes and the single server in the primary queue dispenses an exponentially distributed service time at the rate which is dependent on the customers class. The service discipline is preemptive priority with priority given to class 1 over class 2 customers. In this paper, we use matrix-analytic method to construct the infinitesimal generator of the system and also to provide a detailed analysis of the expected waiting time of each class of customers in both queues.

On a dual queueing system with preemptive priority service discipline

In this paper, we use matrix-analytic methods to construct a novel queueing model called the dual queue. The dual queue has the additional feature of a priority scheme to assist in congestion control. Detailed structure of the infinitesimal generator matrix is derived and used in the solution process. Using a computational algorithm, which utilises a combination of iterative and elementary matrix techniques, the steady state solution is obtained for all queues with a finite buffer. Finally, we present numerical examples to illustrate the algorithm.

The role of satellite data in census: Case study of an Indian State

Countries, such as India, conduct a census collection every ten years. Currently census in India is carried out manually, therefore suffering from a number of shortcomings including inconsistency issues, the Modifiable Areal Unit Problem (MAUP) and large temporal acquisition timeframes. This paper proposes a surrogate census method using satellite images captured at night by DMSP-OLS satellites to overcome some of these drawbacks. The lights on the earth surface captured by this satellite represent areas of human habitation. Correlations between stable lights and brightness information with available census metrics from the last Indian census (2001) were calculated using bootstrapping techniques. Linear regression and multivariate analyses were subsequently performed and models proposed for each of the selected census metrics (e.g population density, number of households per square Kilometre, percentage of households with cars, jeeps and vans, Per Capita District Domestic Product (PCDDP) and urban population density) with results ranging from r 2 of 0.8 to 0.9 at the 95% confidence interval. Census metrics unavailable at spatial scales lower than districts were also predicted using the proposed models and maps were derived showing the predicted measures. The results demonstrate that DMSP-OLS night-time images may be successfully used to estimate census variables in real time.

Predicting a tennis match in progress for sports multimedia

This article demonstrates how spreadsheets can generate the probability of winning a tennis match conditional on the state of the match. Previous models treat games, sets and matches independently. We show how a series of interconnected sheets can be used to repeat these results. The sheets are used in multimedia to predict outcomes for a match in progress, where it is shown how these predictions could benefit the spectator, punter, player and commentator. The development of the predictions could also form an interesting and useful teaching example, and allow students to investigate the properties of tennis scoring systems.

Simulation studies of a multi-priority dual queue (MPDQ) with preemptive and non-preemptive scheduling

Traffic management in communication environments like the Internet is vital in meeting the demand of users. The recent introduction of various dynamic scheduling algorithms has been to target improvements in QoS (Quality of Service). These new algorithms, such as dual queueing, aim to give better QoS to most traffic at the expense of a few rather than fairly give poor QoS to all customers. This is achieved through scheduling decisions that can change depending on the traffic conditions. The MPDQ introduces different classes into this type of scheme with the aim of enhancing higher-class packets QoS without great expense to lower class packets. In this paper we analyse the differences in loss and waiting time between preemptive and non-preemptive service disciplines for the MPDQ and then identify the best queueing regime for the pre-emptive MPDQ. We show that non-preemptive service dispensing is superior to packets of two classes than the preemptive scheme, and that highest class first (HCF) is the best queueing regime for either of these algorithms.

The intra-match home advantage in Australian rules football

The existence of home advantage in Australian Rules football (AFL) has been well documented in previous literature. This advantage typically refers to the net advantage of several factors which, generally speaking, have a positive effect on the home team and a negative effect on the away team. However, this practice excludes the in-course dynamics of home advantage throughout the match including the interrelationship between pre-game and in-game team characteristics. The aim of the present study is to calculate the intra-match home advantage for each quarter in AFL by incorporating the interaction between team quality and current score. Archival AFL data was obtained from seasons 2000 to 2009 which consisted of year, round, quarter, (nominal) home team, away team, home team score and away team score. Analysis of variance (ANOVA) on margin of victory was used to determine if there was a distinct difference between team quality (favourite/underdog) within current score (ahead/behind). Since the in-game team characteristics (current score) are likely to be caused by pre-game characteristics (team quality) the margin of victory is adjusted for team quality. The results provide marginal evidence that home underdogs in the third quarter irrespective of whether they were ahead or behind at half time receive a greater advantage than home favourites. Furthermore, home advantage is greatest in the final quarter when there is a high level of uncertainty about the outcome of the match.

Quality of service in networks with prioritised traffic involving the multi-priority dual queue

The Multi Priority Dual Queue (MPDQ) is a new scheduling regime shown to reduce congestion for multi-class traffic over conventional scheduling disciplines in isolation. As the MPDQ improves traffic congestion, most notably in communication systems, it is not necessary to include it at every node, or service centre, within a network. To gain insight into the advantages of a mixed MPDQ / First In First Out network with prioritised traffic, simulations are performed with and without a dual queue and various Quality of Service (QoS) criteria are obtained. Queueing networks containing differentiated traffic, also known as multi-class networks, are complicated to solve analytically using existing queueing theory techniques. We discuss the complications of exact solutions and describe how we used simulation to obtain performance statistics. We also look at high-class traffic under different offered loads, and provide a comparison of the delay characteristics. These findings provide communication service providers valuable information in determining the improvement in QoS to differentiated networks with the MPDQ. They also highlight the importance of simulation as a tool of evaluation of networks, and the best MPDQ network scenario.