In this paper, we analyze a discrete-time preemptive repeat priority queue with resampling. High-priority packets have preemptive
repeat priority, and interrupted low-priority packets are subjected to independent retransmission attempts. Both classes contain
packets with generally distributed transmission times. We show that the use of generating functions is beneficial for analyzing
the system contents and packet delay of both classes. The influence of the priority scheduling on the performance measures
is illustrated by some numerical examples.
This work has been supported by the Interuniversity Attraction Poles Programme–Belgian Science Policy. 相似文献
In this paper, we study the behavior of a discrete-time multiserver buffer system with infinite buffer size. Packets arrive
at the system according to a two-state Markovian arrival process. The service times of the packets are assumed to be constant,
equal to multiple slots. The behavior of the system is analyzed by means of an analytical technique based on probability generating
functions (PGF’s). Explicit expressions are obtained for the PGF’s of the system contents and the packet delay. From these,
the mean values, the variances and the tail distributions of the system contents and the packet delay are calculated. Numerical
examples are given to show the influence of various model parameters on the system behavior. 相似文献
In this paper, we introduce and analyze a modified HOL (head-of-the-line) priority scheduling discipline. The modification is incorporated to cope with the so-called starvation problem of regular HOL priority queues. We consider a discrete-time single-server queueing system with two priority queues of infinite capacity and with the introduced priority scheme. We show that the use of probability generating functions is suitable for analyzing the system contents and the packet delay. Some performance measures (such as means and variances) of these stochastic quantities will be derived. Furthermore, approximate expressions of the tail probabilities are obtained from the probability generating functions, by means of the dominant-singularity method. These expressions, together with their characteristics, constitute one of the main contributions of this paper. Finally, the impact and significance of the m-HOL (modified HOL) priority scheduling on these performance measures is illustrated by some numerical examples. 相似文献
We present low-frequency Raman scattering of pure GeO(2) glass under pressure up to 4 GPa, corresponding to an elastic transformation. Intensity variation and frequency shift of the boson peak are analysed and compared to the Debye model. The decrease of the boson peak intensity scaled by the Debye energy is correlated to the elastic anomalous properties under pressure up to 1.5 GPa, and interpreted as an elastic homogenisation process at the local scale. We emphasize similarities between a-GeO(2) and a-SiO(2) behavior under pressure, and compare our results to other experiments, numerical studies, and predictions of several models concerning amorphous systems. 相似文献
Priority queueing systems come natural when customers with diversified delay requirements have to wait to get service. The
customers that cannot tolerate but small delays get service priority over customers which are less delay-sensitive. In this
contribution, we analyze a discrete-time two-class preemptive repeat identical priority queue with infinite buffer space and
generally distributed service times. Newly arriving high-priority customers interrupt the on-going service of a low-priority
customer. After all high-priority customers have left the system, the interrupted service of the low-priority customer has
to be repeated completely. By means of a probability generating functions approach, we analyze the system content and the
delay of both types of customers. Performance measures (such as means and variances) are calculated and the impact of the
priority scheduling is discussed by means of some numerical examples. 相似文献
We consider a queueing system with disruptive and non-disruptive server interruptions. Both disruptive and non-disruptive interruptions may start when there is a customer in service. The customer repeats its service after a disruptive interruption, and continues its service after a non-disruptive interruption. Using a transform approach, we obtain various performance measures such as the moments of the queue content and waiting times. We illustrate our approach by means of some numerical examples. 相似文献
Ultrasonic imaging devices often use transducer arrays for sampling the incoming acoustic field and converting it into electrical signals. After some convenient processing (amplification, dephasing, summing, etc), the electrical signals are used to modulate the brightness of a cathode ray tube (crt) monitor on which the ultrasonic image becomes visible. The quality of the imaging apparatus depends critically on the transducer array design and implementation.
Each individual transducer would, ideally, produce an electrical signal related exclusively to the ultrasonic field arriving at its surface; the reciprocal would also be true for transmission. In all practical cases, however, numerous effects lead to some coupling between nearby transducers, especially for very narrow transducers. The subsequent perturbations may be described as a narrowing of the radiation (or reception) pattern of the individual transducers, with respect to the theoretical predictions. To understand the mechanism for these couplings and to minimize them, their possible origins have been systematically studied. One of the most important sources of coupling is electrical leakage, which is reported here. Since no simple analytical calculation can be performed, diagrams have been established that enable evaluation of the electrical coupling against the dimensional characteristics of the array. Some means for reducing this coupling are suggested and comparative experimental results are given. 相似文献
Whereas the buffer content of batch-service queueing systems has been studied extensively, the customer delay has only occasionally
been studied. The few papers concerning the customer delay share the common feature that only the moments are calculated explicitly.
In addition, none of these surveys consider models including the combination of batch arrivals and a server operating under
the full-batch service policy (the server waits to initiate service until he can serve at full capacity). In this paper, we
aim for a complete characterisation—i.e., moments and tail probabilities - of the customer delay in a discrete-time queueing
system with batch arrivals and a batch server adopting the full-batch service policy. In addition, we demonstrate that the
distribution of the number of customer arrivals in an arbitrary slot has a significant impact on the moments and the tail
probabilities of the customer delay. 相似文献