The spectral gap for quasi-birth and death processes

For a reversible quasi-birth and death process, we generalize and refine the decomposition method, by constructing a birth-death process and a sequence of restriction processes. The spectral gap for the quasi-birth and death process is estimated in terms of the spectral gaps for these processes, and in some special cases, the estimation is sharp. With the aid of the symmetrization procedure, the result is also applied to two queueing models: M/M/1 in random environment and M/M/c with synchronous vacation.     

度假旅游情境中地方依恋对游客公民行为的影响——基于心理所有权视角

游客公民行为是促进旅游地保持竞争力、实现持续发展的重要推手,现有研究主要参照顾客公民行为的逻辑框架,未能突出旅游情境和游客群体的独特性。以浙江省3个国家级旅游度假区游客为研究对象,基于社会交换理论和心理所有权理论,构建了一个可调节的中介模型,探究地方依恋、地方心理所有权、自我提升动机与游客公民行为的关系。用SPSS 22.0和AMOSS 23.0软件分析收集到的419份样本数据,结果表明：地方依恋正向影响地方心理所有权和游客公民行为;地方心理所有权正向影响游客公民行为;地方心理所有权对地方依恋与游客公民行为之间的关系起部分中介作用;自我提升动机正向调节地方心理所有权与游客公民行为的关系,同时正向调节地方心理所有权的中介作用。     

A 3-queue polling system with join the shortest-serve the longest policy

In 1987, J.W. Cohen analyzed the so-called Serve the Longest Queue (SLQ) queueing system, where a single server attends two non-symmetric $M/G/1$-type queues, exercising a non-preemptive priority switching policy. Cohen further analyzed in 1998 a non-symmetric 2-queue Markovian system, where newly arriving customers follow the Join the Shortest Queue (JSQ) discipline. The current paper generalizes and extends Cohen’s works by studying a combined JSQ–SLQ model, and by broadening the scope of analysis to a non-symmetric 3-queue system, where arriving customers follow the JSQ strategy and a single server exercises the preemptive priority SLQ discipline. The system states’ multi-dimensional probability distribution function is derived while applying a non-conventional representation of the underlying process’s state-space. The analysis combines both Probability Generating Functions and Matrix Geometric methodologies. It is shown that the joint JSQ–SLQ operating policy achieves extremely well the goal of balancing between queue sizes. This is emphasized when calculating the Gini Index associated with the differences between mean queue sizes: the value of the coefficient is close to zero. Extensive numerical results are presented.     

网络结构优化设计模型及遗传算法

本文以网型通信网问题为列建立了优化问题的数学模型，并用遗传算法并行求解该问题，该方法较好地解决了既考虑经济效益又考虑需求的网络结构优化问题，该问题的研究对实际应用及动态网络的研究有十分重要的意义。