Bayesian analysis of queues with impatient customers: Applications to call centers

Queuing models have been extensively used in the literature for obtaining performance measures and developing staffing policies. However, most of this work has been from a pure probabilistic point of view and has not addressed issues of statistical inference. In this article, we consider Bayesian queuing models with impatient customers with particular emphasis on call center operations and discuss further extensions. We develop the details of Bayesian inference for queues with abandonment such as the M/M/s + M model (Erlang‐A). In doing so, we discuss the estimation of operating characteristics and its implications on staffing. We illustrate the implementation of the Bayesian models using actual arrival, service, and abandonment data from call centers. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

A quasi-isentropic model of a cylinder driven by aluminized explosives based on characteristic line analysis

A quasi-isentropic study on the process of driving a cylinder with aluminized explosives was carried out to examine the influence of the aluminum (Al) reaction rate on cylinder expansion and the physical parameters of the detonation products. Based on the proposed quasi-isentropic hypothesis and relevant isentropic theories, the characteristic lines of aluminized explosives driving a cylinder were analyzed, and a quasi-isentropic model was established. This model includes the variation of the cylinder wall velocity and the physical parameters of the detonation products with the Al reaction degree. Using previously reported experimental results, the quasi-isentropic model was verified to be applicative and accurate. This model was used to calculate the physical parameters for cylinder experiments with aluminized cyclotrimethylenetrinitramine explosives with 15.0 % and 30.0 % Al content. The results show that this quasi-isentropic model can be used not only to calculate the cylinder expansion rule or Al reaction degree, but also to calculate the physical parameters of the detonation products in the process of cylinder expansion. For explosives with 15.0 % and 30.0 % Al, 24.3 % and 18.5 % of the Al was found to have reacted at 33.9 μs and 34.0 μs, respectively. The difference in Al content results in different reaction intensity, occurrence time, and duration of two forms of reaction (diffusion and kinetic) between the Al powder and the detonation products; the post-detonation burning reaction between the Al powder and the detonation products prolongs the positive pressure action time, resulting in a continuous rise in temperature after detonation.     

Analysis of the effect of bore centerline on projectile exit conditions in small arms

Most finite element models of small arms focus on an idealized barrel, typically one with a perfectly straight bore centerline. Using five different experimentally measured bore centerlines, this investigation analyzes the effect centerline nonlinearity has on projectile exit conditions. This includes the effect of rotating a centerline through several orientations. Modeled using Abaqus/Explicit, this dynamic analysis simulates a single firing cycle for each centerline. Projectile jump is calculated for each model as a measure of the effects of warped centerlines. The warped centerlines have a small effect on barrel dynamics.     

小学语文课外阅读中协同知识建构的特征研究

小学阶段是培养学生阅读兴趣的重要阶段,这一阶段应该以多种形式开展课外阅读以培养学生的阅读素养。知识建构在培养学生语言能力、审美、鉴赏、创造思维、文化传承与理解方面发挥着重要的作用,在小学语文课外阅读中有广泛的应用空间。研究以小学五年级所开展的课外阅读为例,对学生在课外阅读中协同知识建构过程进行了分析,发现课外阅读过程中的协同知识建构具有过程性、自发性、可持续发展性的特征,对培养学生的口语表达能力、审美能力、创作能力和人际交往能力有积极的作用。     

中国维和警察特色理论研究

中国维和警察特色理论是中国维和警察学科理论体系基本框架的重要组成部分。对中国维和警察特色理论的概念、主体、特征、范畴进行了探讨,以构建中国维和警察特色理论的基本框架,为中国维和警察学科理论体系研究奠定坚实基础。     

基于灰色模型的柴油机技术状态变化趋势预测

以某型坦克用柴油机为平台进行了大量实车实验,确定了能够表征柴油机技术状态变化的6个特征量,利用主成分分析法确定了柴油机寿命预测特征量;建立了灰色预测模型,并基于所测数据进行了技术状态变化趋势预测。研究结果表明：预测值接近于实际值,能够为柴油机的使用和合理维修提供依据。     

某型坦克炮炮闩击发机构故障仿真分析

针对坦克炮炮闩的常见故障和失效形式,建立了坦克炮炮闩击发机构的虚拟样机,进行了运动和动力仿真。利用多体动力学仿真方法对坦克炮炮闩击发机构的典型故障机理进行了分析,为分析炮闩故障机理、改进炮闩结构和提高可靠性提供了理论依据。     

基于熵权的机械传动系统方案评价的模糊AHP法

针对机械传动系统涉及因素较多且各因素具有不同程度的模糊性的特点,分析了机械传动系统方案的评价指标,建立了方案评价指标体系,并运用基于熵权的模糊层次分析法(AHP)建立了机械传动系统方案评价模型.以一个带式输送机的传动方案为例,成功选出了适合已知工况的最佳方案,验证了方法的有效性.     

一种面向频域的通信信号盲干扰检测算法

针对低干信比和复杂动态情况下传统的干扰检测算法效率不高的问题,提出一种基于盲通信信号频域处理的未知干扰自动检测算法。该方法首先借助快速独立成份分析(FICA)从频谱差分数据中分离干扰和通信信号成份分量,然后利用各分量的峰度作为干扰与通信信号的识别特征检测干扰。实验结果表明,此算法能有效地在干信比小于5 dB的情况下从盲通信信号背景中自动提取未知干扰的信息,实现高精度地盲干扰检测。