The M/M\1 queue in a heavy-tailed random environment

We consider an M / M /1 queue with the special feature that the speed of the server alternates between two constant values s_L and s_H > s_L . The high-speed periods are exponentially distributed, and the low-speed periods have a regularly varying distribution. We obtain explicit asymptotics for the tail of the workload distribution. The two cases in which the offered traffic load is smaller respectively larger than the low service speed are shown to result in completely different asymptotics.     

A Path Construction for the Virtual Waiting Time of an M/G/1 Queue

Consider the M/G/1 queue, the finite dam M/G/1 with capacity T, and the impatient customer M/G/1 model, where customers become lost customers if their waiting time exceeds τ. In this note we prove that for all three models and each xe(0, r) the distribution of the number of downcrossings of the virtual waiting time process with level x during a busy cycle is identical. This implies the weaker statement that on [0, T) the distribution functions of the steady state distributions of the amount of unprocessed work (virtual waiting time) are proportional. A number of applications is given.     

A Simple Proof of the Equivalence of the Limiting Distributions of the Continuous-Time and the Embedded Process of the Queue Size in the M/G/1 Queue*

This paper presents an extremely simple proof of the known remarkable fact that for the M/G/1 queue the continuous-time process describing the number of customers in the system has the same limiting distribution as the embedded process describing the number of customers in the system just after service completion epochs.     

2000～2005年西方作业成本(ABC/M)研究综述

本文对西方国家2000￣2005年ABC/M的研究成果进行了分析,观察国外研究者的研究内容和研究方法的选择,分析了ABC/M的研究发展趋势,希望对今后的研究提供参考,并对ABC/M文献研究有所贡献。     

The M/G/∞ Queueing Model for Optimistic Concurrency Control

The M / G /∞ queue with Optimistic Concurrency Control (OCC) is a model for a special form of parallel transaction processing in a real-time database. Transactions arrive according to a Poisson process and require some generally distributed execution time. One of the differences with ordinary multi- and infinite-server queueing models is that under OCC the successful completion of one transaction may immediately cause the failure of one or more of the other transactions. This happens if the completing transaction has overwritten a data-item that is in use by another transaction in progress. As soon as this failure is detected the failed transaction is restarted. So the total service time of a transaction consists of its final successful run and the time spent on unsuccessful runs.
In this study we develop an approximation for the distribution of the total service time, and test the approximation against simulation. Although in practice the number of servers is never unlimited, this study provides valuable insight in the asymptotics with respect to the number of servers. The approximation clearly demonstrates the very limited performance gain from an increase of the number of servers.     

国际航运业并购动机及其对我国航运企业的启示

首先分析了国际航运业的并购趋势,然后总结了国际航运企业并购的动机,即通过横向并购扩大市场份额,通过纵向并购拓展企业价值链实现向综合物流企业的转变以及混合并购以分散经营风险。     

The M/M/1 queue with gated random order of service

We analyse an M / M /1 queueing model with gated random order of service discipline. In this service discipline there is a waiting room, in which arriving customers are collected, and a service queue. Each time the service queue becomes empty, all customers in the waiting room are instantaneously put in random order in the service queue. We find the joint stationary distribution of the number of customers in the waiting room and the service queue. Furthermore, we obtain the bivariate Laplace–Stieltjes transform of the joint distribution of the sojourn times of a customer in the waiting room and the service queue.     

Back to the roots of the M/D/s queue and the works of Erlang, Crommelin and Pollaczek

A.K. Erlang introduced the M/D/ s queue in 1917, while F. Pollaczek and C.D. Crommelin formalized the theory using complex analysis and transforms. Let D ( s , λ ) denote the stationary probability of experiencing no waiting time in the M/D/ s queue with arrival rate λ and service requirement 1. We use D ( s , λ ) as a vehicle to give an overview of some of the results we obtained over the last years, including explicit characterizations of the roots, the derivation of infinite series from expressions in terms of roots using Fourier sampling and heavy-traffic limits obtained from square-root staffing. We propose to call D ( s , λ ) the Erlang D formula, for which several new results are presented and compared with the results of Pollaczek.     

基于排队论的航空保障资源配置研究

航空母舰航空保障战位的优化配置在某种程度上影响着舰载机的最大出动强度。通过明确航空站位数量的设置与舰载机及母舰的运行成本之间的关系,可以确定航空保障站位的优化配置数量。本文以俄罗斯航母为模型,运用排队论思想对舰载机等待保障的M/M/1模型进行算例计算及仿真研究,分析出满足舰载机航空勤务保障的合理优化配置数量,研究发现,航空保障站位的配置数量以7组为最佳,此方法可为航空保障资源配置方案的设计提供一定的理论支撑。     

道路运输行业面向节能减排的I/M制度检测方法研究

I/M制度是保证汽车处于良好的技术状况,投资最少、最有效、最根本的途径。文章介绍了适用于我国道路运输行业现状的I/M制度在实施时所能采用的检测方法。并且对这些检测方法进行了详细的分析及比较。     

物联网技术在药品物流管理系统中的应用

药品安全及成本问题一直是我国药品物流行业发展的两大障碍,药品物流环节繁杂、效率低、成本高。针对该问题,利用物联网技术,通过建立药品物流管理系统,实现药品实时跟踪监控、透明管理,确保药品安全及成本最优。文章分析我国药品物流行业特点及存在问题,结合物联网相关技术构建药品物流管理系统,介绍系统应用流程及实施关键。     

Predicting/hypothesizing the findings of the M5 competition

The scientific method consists of making hypotheses or predictions and then carrying out experiments to test them once the actual results have become available, in order to learn from both successes and mistakes. This approach was followed in the M4 competition with positive results and has been repeated in the M5, with its organizers submitting their ten predictions/hypotheses about its expected results five days before its launch. The present paper presents these predictions/hypotheses and evaluates their realization according to the actual findings of the competition. The results indicate that well-established practices, like combining forecasts, exploiting explanatory variables, and capturing seasonality and special days, remain critical for enhancing forecasting performance, re-confirming also that relatively new approaches, like cross-learning algorithms and machine learning methods, display great potential. Yet, we show that simple, local statistical methods may still be competitive for forecasting high granularity data and estimating the tails of the uncertainty distribution, thus motivating future research in the field of retail sales forecasting.     

M2M消防远程监控系统的应用

文章把M2M的概念引入消防远程监控系统中应用,消防远程监控系统通过运营商网络将各建筑物内独立的火灾自动报警系统联网,在监控中心内对所有联网建筑物的火灾报警情况进行实时监测,对消防设施进行集中管理。     

M2M消防远程监控系统的应用

文章把M2M的概念引入消防远程监控系统中应用,消防远程监控系统通过运营商网络将各建筑物内独立的火灾自动报警系统联网,在监控中心内对所有联网建筑物的火灾报警情况进行实时监测,对消防设施进行集中管理。     

The M5 competition: Background,organization, and implementation

The M5 competition follows the previous four M competitions, whose purpose is to learn from empirical evidence how to improve forecasting performance and advance the theory and practice of forecasting. M5 focused on a retail sales forecasting application with the objective to produce the most accurate point forecasts for 42,840 time series that represent the hierarchical unit sales of the largest retail company in the world, Walmart, as well as to provide the most accurate estimates of the uncertainty of these forecasts. Hence, the competition consisted of two parallel challenges, namely the Accuracy and Uncertainty forecasting competitions. M5 extended the results of the previous M competitions by: (a) significantly expanding the number of participating methods, especially those in the category of machine learning; (b) evaluating the performance of the uncertainty distribution along with point forecast accuracy; (c) including exogenous/explanatory variables in addition to the time series data; (d) using grouped, correlated time series; and (e) focusing on series that display intermittency. This paper describes the background, organization, and implementations of the competition, and it presents the data used and their characteristics. Consequently, it serves as introductory material to the results of the two forecasting challenges to facilitate their understanding.     

基于排队论的集成电路出货检验研究

通过应用排队论（M/M/s）,对某集成电路生产线出货检验工作进行研究,分析和评价产品在出货检验站点排队与滞留状况及其原因,为节约产品排队时间,提高出货检验站点的质量、效率,以及平衡产品排队时间与出货检验站点效率之间的关系提供一种较有效的管理决策手段。     

论标准化在测绘工作中的重要性

为使测绘从业人员充分认识到标准化工作的重要性，从而在测绘工作中自觉执行各类标准，从标准和标准化的定义入手，由浅入深地阐明了标准在测绘工作中的重要性，即执行测绘标准是法治意识的重要体现；标准化是保持测绘科技先进性的重要手段；标准化是测绘成果统一性的重要保障；标准化是维护测绘市场公平竞争的重要工具。论述的观点，对把测绘标准化工作引向深入具有一定的参考价值。     

基于战略沟通的企业并购文化整合传播研究

企业并购是经济全球化时代企业扩张的重要途径。但是巨大的并购数目与惊人的高失败率形成强烈的反差,特别是并购后期的文化整合是一项复杂的系统工程,也是企业并购成败的关键。面对文化整合困境,本文强调战略沟通的基础作用,尝试就企业并购文化整合传播提出了分析框架,为解决企业并购中的文化整合难题拓展了新的分析视角,旨在对中国企业国际化拓展和海外经营提供借鉴和参考。     

浅议并购合同风险研究的必要性

并购让企业跳跃式发展,但也面临诸多风险。并购合同是防范并购风险的重要机制,但学界业界对此研究甚少。本文通过并购合同法律地位、并购合同风险研究现状、现实和理论必要性几方面浅议并购合同风险研究的必要性。     

The M4 Competition: 100,000 time series and 61 forecasting methods

The M4 Competition follows on from the three previous M competitions, the purpose of which was to learn from empirical evidence both how to improve the forecasting accuracy and how such learning could be used to advance the theory and practice of forecasting. The aim of M4 was to replicate and extend the three previous competitions by: (a) significantly increasing the number of series, (b) expanding the number of forecasting methods, and (c) including prediction intervals in the evaluation process as well as point forecasts. This paper covers all aspects of M4 in detail, including its organization and running, the presentation of its results, the top-performing methods overall and by categories, its major findings and their implications, and the computational requirements of the various methods. Finally, it summarizes its main conclusions and states the expectation that its series will become a testing ground for the evaluation of new methods and the improvement of the practice of forecasting, while also suggesting some ways forward for the field.