A discrete-time HOL priority queue with multiple traffic classes.

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Delay Analysis of a Discrete-Time Non-Preemptive Priority Queue with Priority Jumps

In this paper, we consider a discrete-time non-preemptive priority queueing model with priority jumps. Two classes, real-time (high priority) and non-real time (low priority), of traffic will be considered with providing jumps from lower priority traffic to the queue of high priority traffic. We derive expressions for the joint probability generating function of the system contents of the high and the low priority traffic in the steady state and also for some performance measures such as the mean value of the system contents and the packet delay. The behavior of the priority queues with priority jumps will be illustrated by using these results and is compared to the FIFO scheme

Low-percentage Ln3+ doping in a tetranuclear lanthanum polyoxometalate assembled from [Mo7O24]6- polyanions yielding visible and near-infrared luminescence

A rare case of low-percentage trivalent lanthanide doping in multinuclear lanthanide polyoxometalates (LnPOMs) was investigated. The [La-4(MoO4) (H2O)(16-) (Mo7O24)(4)](14-) polyanion was chosen as the host material for this study. In this polyanion the central [La-4(MoO4)](10+) core is coordinated by four heptamolybdate groups as well as 16 water molecules. The tetranuclear lanthanum POM was doped with 5% of Eu3+, Tb3+, Sm3+, Dy3+, Nd3+, Er3+, and Yb3+ (according to synthesis), and the structures and luminescence properties of the x%Ln:LaPOMs were investigated. Additionally a series of tetranuclear lanthanide POMs built from [Mo7O24](6-) heptamolybdate polyanions with Eu3+, Tb3+, Sm3+, Dy3+, and Nd3+ instead of La3+ were synthesized, and a detailed analysis revealed that the tetranuclear clusters formed monomers or dimers linked through oxygen bridges. The smaller lanthanide ions, namely, Er3+ and Yb3+, did not form tetranuclear clusters, but instead mononuclear sandwich-type POMs were obtained. The obtained structures were shown to be lanthanide-specific, and not a result of different synthetic/crystallization conditions. The luminescence properties of the x%Ln:LaPOMs were compared with the luminescence properties of the LnPOMs

Communication models for monitoring and mobility verification in mission critical wireless networks

Recent technological advances have seen wireless sensor networks emerge as an interesting research topic because of its ability to realize mission critical applications like in military or wildfire detection. The first part of the thesis focuses on the development of a novel communication scheme referred here as a distributed wireless critical information-aware maintenance network (DWCIMN), which is presented for preventive maintenance of network-centric dynamic systems. The proposed communication scheme addresses quality of service (QoS) issues by using a combination of a head-of-the-line queuing scheme, efficient bandwidth allocation, weight-based backoff mechanism, and a distributed power control scheme. A thorough analysis of a head-of-the-line priority queuing scheme is given for a single-server, finite queue with a batch arrival option and user priorities. The scheme is implemented in the Network Simulator (NS-2), and the results demonstrate reduced queuing delays and efficient bandwidth allocation for time-critical data over non time critical data. In the second part, we introduce a unique mobility verification problem in wireless sensor networks wherein the objective is to verify the claimed mobility path of a node in a co-operating mission critical operation between two allies. We address this problem by developing an efficient power-control based mobility verification model. The simulation framework is implemented in Matlab and the results indicate successful detection of altered claimed paths within a certain error bound --Abstract, page iii

Discrete-time queueing models with priorities

This PhD-dissertation contains analyses of several discrete-time two-class priority queueing systems. We analyze non-preemptive, preemptive resume as well as preemptive repeat priority queues. The analyses are heavily based on probability generating functions that allow us to calculate moments and tail probabilities of the system contents and packet delays of both classes. The results are applicable in heterogeneous telecommunication networks, when delay-sensitive traffic gets transmission priority over best-effort traffic. Our results predict the influence of priority scheduling on the QoS (Quality-of-Service) of the different types of traffic