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**排序方式：**共有3958条查询结果，搜索用时 15 毫秒

1.

The age of information (AoI) metric was proposed to measure the freshness of messages obtained at the terminal node of a status updating system. In this paper, the AoI of a discrete time status updating system with probabilistic packet preemption is investigated by analyzing the steady state of a three-dimensional discrete stochastic process. We assume that the queue used in the system is $Ber/Geo/1/{2}^{*}/\eta $, which represents that the system size is 2 and the packet in the buffer can be preempted by a fresher packet with probability $\eta $. Instead of considering the system’s AoI separately, we use a three-dimensional state vector $(n,m,l)$ to simultaneously track the real-time changes of the AoI, the age of a packet in the server, and the age of a packet waiting in the buffer. We give the explicit expression of the system’s average AoI and show that the average AoI of the system without packet preemption is obtained by letting $\eta =0$. When $\eta $ is set to 1, the mean of the AoI of the system with a $Ber/Geo/1/{2}^{*}$ queue is obtained as well. Combining the results we have obtained and comparing them with corresponding average continuous AoIs, we propose a possible relationship between the average discrete AoI with the $Ber/Geo/1/c$ queue and the average continuous AoI with the $M/M/1/c$ queue. For each of two extreme cases where $\eta =0$ and $\eta =1$, we also determine the stationary distribution of AoI using the probability generation function (PGF) method. The relations between the average AoI and the packet preemption probability $\eta $, as well as the AoI’s distribution curves in two extreme cases, are illustrated by numerical simulations. Notice that the probabilistic packet preemption may occur, for example, in an energy harvest (EH) node of a wireless sensor network, where the packet in the buffer can be replaced only when the node collects enough energy. In particular, to exhibit the usefulness of our idea and methods and highlight the merits of considering discrete time systems, in this paper, we provide detailed discussions showing how the results about continuous AoI are derived by analyzing the corresponding discrete time system and how the discrete age analysis is generalized to the system with multiple sources. In terms of packet service process, we also propose an idea to analyze the AoI of a system when the service time distribution is arbitrary. 相似文献

2.

A new Markov process describing crystal growth in three dimensions is introduced. States of the process are configurations of the crystal surface, which has a terrace-edge-kink structure. The states are continuous along edges but discrete across edges, in accordance with the very different rates for the two types of captures of particles. Stationary distributions, describing steady crystal growth, are found in general. To our knowledge, these are the first examples of stationary distributions for layered crystal growth in three dimensions. The steady growth rate and other quantities are obtained explicitly for two interacting edges. For many interacting edges, growth behavior is determined (a) in various asymptotic regimes including thermodynamic limits, (b) via simulations, and (c) using series (cluster) expansions in the slope of the surface, the first three coefficients being computed. The theoretical growth rates show a marked dependence on surface dimensions. This may contribute to the size dependence and dispersion in the observed growth rate of small crystals. 相似文献

3.

4.

BaFClxBr1－x:Sm2+中5D2→7F0跃迁几率及其对烧孔效率的影响

**总被引：1，自引：0，他引：1**本文以BaFClxBr1－x:Sm2+中5D2→7F0的跃迁几率随x变化为中心对BaFClxBr1－x:Sm2+体系4f5d带的激发光谱、5D2→7F0跃迁的荧光衰减随温度的变化特性、5D2→7F0的跃迁几率等进行了研究。从而得出结论:在BaFClxBr1－x:Sm2+中,随Br含量的增大,4f5d带与5D2能级更加接近,使7F0→5D2的吸收截面增大,从而可能提高在5D2:能级烧孔的效率。 相似文献

5.

It is known that at the critical temperature the Curie-Weiss mean-field model has non-Gaussian fluctuations and that internal fluctuations can be Gaussian. Here we compute the distribution of the

*q*-mode magnetization fluctuations as a function of the temperature, the wave vector*q*, and a fading out external field. We obtain new classes of probability distributions generated by this external field as well as new critical behavior in terms of its rate of fading out. We discuss also the susceptibility as the limit*q*tending to zero. 相似文献6.

V. V. Kalashnikov 《Queueing Systems》1990,6(1):113-136

Recently developed methods of qualitative analysis for regenerative processes arising in queueing are presented. These methods
are essentially qualitative and use notions such as coupling, probability metrics, etc. They are developed for studying various
properties of regenerative models, including convergence rate to a stationary regime, continuity of their characteristics
with respect to some parameters and first-occurrence time of an event such as queue overflowing. In spite of their qualitative
nature they lead to good quantitative estimates of underlying properties with computer methods available to calculate them. 相似文献

7.

In this paper, we investigate the exact distribution of the waiting time for the

*r*-th ℓ-overlapping occurrence of success-runs of a specified length in a sequence of two state Markov dependent trials. The probability generating functions are derived explicitly, and as asymptotic results, relationships of a negative binomial distribution of order*k*and an extended Poisson distribution of order*k*are discussed. We provide further insights into the run-related problems from the viewpoint of the ℓ-overlapping enumeration scheme. We also study the exact distribution of the number of ℓ-overlapping occurrences of success-runs in a fixed number of trials and derive the probability generating functions. The present work extends several properties of distributions of order*k*and leads us a new type of geneses of the discrete distributions. 相似文献8.

Su-Yun Huang Chuhsing Kate Hsiao Ching-Wei Chang 《Annals of the Institute of Statistical Mathematics》2003,55(3):655-670

The article provides a refinement for the volume-corrected Laplace-Metropolis estimator of the marginal likelihood of DiCiccio

*et al.*The correction volume of probability α in DiCiccio*et al.*is fixed and suggested to take the value α=0.05. In this article α is selected based on an asymptotic analysis to minimize the mean square relative error (MSRE). This optimal choice of α is shown to be invariant under linear transformations. The invariance property leads to easy implementation for multivariate problems. An implementation procedure is provided for practical use. A simulation study and a real data example are presented. 相似文献9.

Mieko Tanaka-Yamawaki 《Annals of the Institute of Statistical Mathematics》2003,55(2):437-446

Contrary to the common sense in economics and financial engineering, price fluctuations at very fine level of motion exhibit
various evidences against the efficient market hypothesis. We attempt to investigate this issue by studying extensive amount
of foreign currency exchange data for over five years at the finest level of resolution. We specifically focus on the proposed
stability in binomial conditional probabilities originally found in much smaller examples of financial time series. In order
to handle very large data, we have written an efficient program in C that automatically generates those conditional probabilities.
It is found that the stability is maintained for extremely large time duration that covers almost the entire period. Based
on the length of conditions for which the conditional probabilities are distinguishable each other, we identify the length
of memory being less than 3 movements. 相似文献

10.

G. Jumarie 《Applied Mathematics Letters》2003,16(8):1171-1177

By combining the Kramers-Moyal expansion with fractional Brownian motion of order

*n*, in a formal symbolic calculus, one can obtain an approximation for the solution of some stochastic differential equations involving both Gaussian and Poissonian white noises, in terms of rotating Gaussian white noises on the grid defined by the complex roots of the unity. Illustrative examples are outlined. 相似文献