A Retrial Queue with a Constant Retrial Rate,Server Downs and Impatient Customers

ABSTRACT

In this paper, we consider a retrial queueing system consisting of a waiting line of infinite capacity in front of a single server subject to breakdowns. A customer upon arrival may join the queue (waiting line) or go to the retrial orbit (another queue) to retry for service after a random time. Only the customer at the head of the retrial orbit is allowed to retry for service. Upon retrial, the customer enters the service if the server is idle; otherwise, it may go back to the retrial orbit or leave the system (become impatient). All the interarrival times, service times, server up times, server down times and retrial times are exponential, and all the necessary independence conditions in these variables are assumed. For this system, we provide sufficient conditions under which, for any given number of customers in the orbit, the stationary probability of the number of customers in the waiting line decays geometrically. We also provide explicitly an expression for the decay parameter.     

Participation and Emotions: Troubling Encounters Between Children and Social Welfare Professionals

This paper explores the emotional aspects of participation within social welfare contexts. The focus is on individual professionals, such as social workers and children’s rights workers and their articulation, management and negotiation of the emotional when working with children and young people. The institutions of welfare are also shown to be ambiguous in their approaches to participation. Lastly, the dimensions of power that are enacted in relations between professionals and children reveal some of the complex dynamics in this fraught area of social welfare policy and practice.     

有关PTC现象的理论研究进展

概要介绍了PTC理论及与PTC现象密切相关的相变理论的研究进展 ,分析了解释PTC现象的一些典型理论模型的发展概况     

SAW振荡器的相位噪声分析

声表面波振荡器是一种典型的反馈振荡器。根据Ｌｅｅｓｏｎ反馈振荡器相位噪声模型，分析了ＳＡＷ振荡器的相位噪声特点，特别是不同的ＳＡＷ反馈元件，分析结果表明不同的ＳＡＷ反馈元件通常有不同的相位噪声特点。还讨论了降低相位噪声电平，提高振荡器的谱密度的方法和途径     

含意阶段性特征的语用视角阐释

融入合作的隐喻含意策略不仅为隐喻功能的施展起到了引领和护航的作用,而且还为隐喻含意的生成和推论提供了上限参照标准,比照着其下限保障机制--隐喻含意生成策略准则和隐喻含意推论策略准则,我们就能对隐喻含意实施操控.通过对融入合作的隐喻含意策略和隐喻含意生成策略准则和隐喻含意推论策略准则的互动分析,含意研究的阶段性特征及其运作机制呈现在我们的面前.     

自来水中增塑剂的检出方法及臭氧化去除方法的研究

本文采用大孔树脂富集和气质联机法(GC/MS)方法,分析了自来水中存在的增塑剂的种类,并采用臭氧氧化方法,对比了自来水经处理后增塑剂种类的变化。     

诱导规范场的Aharonov－Bohm效应和Suter实验中的几何相因子

结合诱导规范场的概念，分析了诱导规范场的Ａｈａｒｏｎｏｖ－Ｂｏｈｍ效应。给出了Ｓｕｔｅｒ实验中规范势与Ｂｅｒｒｙ相因子、规范势与Ａｈａｒｏｎｏｖ－Ａｎａｎｄａｎ相因子之间的关系。     

中国农村土地制度改革过程的变通性、阶段性和一贯性

本文讨论了当代中国农村土地制度改革过程的变通性、阶段性和一贯性,认为:农村土地制度改革的发生和发展以一种"换药不换汤"的方式不断前进,其结果是"汤药并换",但达成这一结果的过程却"润物细无声";农村土地制度变迁过程可以划分为几个明显的不同阶段,每一阶段都存在着需要解决的特定问题,规定着特定的改革目标和任务;从外观上看,20多年的农村土地制度改革是"摸着石头过河",似乎缺乏改革方案的系统设计,但在纷繁复杂的诸多"变通"的、有时还矛盾的历史形式之下,却有一条不依人们的主观愿望为转移的"红线"贯穿始终。     

相变对陶瓷高压容器的韧化作用

本文利用二相粒子可提高陶瓷断裂韧性的特点，将其用于电瓷材料高压容器，理论计算结果表明，相变将会使容器的标称应力和极限内压大大提高．     

未冻水在冻土热状况数值模拟中作用的分析

以Alaska北极美国Barrow气象观测站的地温观测资料和土壤热物理参数为基础,以伴有相变问题的一维热传导方程的有限差分法为工具,在考虑和忽略未冻水2种情形下模拟了Barrow地区0.29,0.50和1.0 m深处的地温值,并与观测值进行了比较.计算结果表明,未冻水对冻土热状况数值模拟结果有很大影响.