A Maintenance Service Improvement Approach Based on Queue Networks: Application

The quest to increase the performance of production systems that have become complex leads to the transfer to the maintenance function of the responsibility of guaranteeing the availability of such systems. Also, we will never stop saying that maintenance must integrate into all of the company’s initiatives, to affirm its role, which is to ensure greater availability and sustainability of the means of production. The objective of this paper is to evaluate the reliability and availability of a system without knowing the distribution law of the operating times. Among the methods for evaluating dependability criteria (Fault Trees, Petri Nets, etc.), we are interested in queues that have the advantage of taking into account functional dependencies, thus allowing a quantified optimization of maintenance. Indeed, queues make it possible to model parallel or sequential processes, implementing operations taking place at the same time or one after the other, meeting the needs of modeling production systems. The main result of this paper is the study of the influence of availability on the reliability of a multi-state production system.

A Fully Adaptive Active Queue Management Method for Congestion Prevention at the Router Buffer

Active queue management(AQM)methods manage the queued packets at the router buffer,prevent buffer congestion,and stabilize the network performance.The bursty nature of the traffic passing by the network routers and the slake behavior of the existing AQM methods leads to unnecessary packet dropping.This paper proposes a fully adaptive active queue management(AAQM)method to maintain stable network performance,avoid congestion and packet loss,and eliminate unnecessary packet dropping.The proposed AAQM method is based on load and queue length indicators and uses an adaptive mechanism to adjust the dropping probability based on the buffer status.The proposed AAQM method adapts to single and multiclass traffic models.Extensive simulation results over two types of traffic showed that the proposed method achieved the best results compared to the existing methods,including Random Early Detection(RED),BLUE,Effective RED(ERED),Fuzzy RED(FRED),Fuzzy Gentle RED(FGRED),and Fuzzy BLUE(FBLUE).The proposed and compared methods achieved similar results with low or moderate traffic load.However,under high traffic load,the proposed AAQM method achieved the best rate of zero loss,similar to BLUE,compared to 0.01 for RED,0.27 for ERED,0.04 for FRED,0.12 for FGRED,and 0.44 for FBLUE.For throughput,the proposed AAQM method achieved the highest rate of 0.54,surpassing the BLUE method’s throughput of 0.43.For delay,the proposed AAQM method achieved the second-best delay of 28.51,while the BLUE method achieved the best delay of 13.18;however,the BLUE results are insufficient because of the low throughput.Consequently,the proposed AAQM method outperformed the compared methods with its superior throughput and acceptable delay.

基于DQueue和CCF的消息队列设计要点分析

消息队列作为一种常见的数据结构,在应用程序和软件操作系统中得到了广泛应用,而随着处理器的不断迭代,传统的锁同步消息队列逐渐无法发挥多核处理器的性能。因此,研究人员尝试引入布谷鸟过滤器(Cuckoo Filter,CCF)和DQueue技术对消息队列进行优化升级,创建云开发消息队列(Cloud Development Message Queue,CDMQ)。基于上述两种技术同时生成多个队列写入数据,操作者利用CCF对数据进行过滤检验,并读取相关信息。通过对CDMQ的性能测试,研究人员证明该消息队列结构具有伸缩性强和吞吐量高等优势,对提高消息队列性能具有重要意义。

LabVIEW中Queue技术在发电机监测系统中的应用

介绍了基于虚拟仪器的在线监测系统的基本组成,其采用PCI总线仪器和LabVIEW可视化的虚拟仪器系统开发平台,把传统仪器的所有功能模块集成在一台计算机中,用户可以通过修改虚拟仪器的软件改变其功能与规模。该系统有效地利用了LabVIEW提供的同步控制Queue技术实现了发电机在现场运行环境下运行状态的监测显示,体现出了其一定的优势。

基于Message Queue技术的医疗信息交换与共享集成平台研究

对目前医院信息系统集成方式进行了分析,简单介绍了IBM Message Queue的技术特点,通过介绍重症监护系统(ICU系统)和HIS系统之间的集成方案,阐述了基于消息机制构建医疗信息交换与共享集成平台的思路和方法。

FastQueue:一种高性能的磁盘队列存储管理机制

1.引言 随着消息通信(如消息、短消息)的爆炸式增长,消息传递系统的性能面临严峻的挑战.消息通信的首要特点是高可靠性,在发送人确认消息收到之前必须将消息保存到磁盘上.

A Multi-Stage Queue Approach to Solving Customer Congestion Problem in a Restaurant

The multistage queue model was developed for a situation where parallel and unrelated queues exist at the first stage only. These queues merged into single queues at the remaining stages. The parallel queues offer services that are different from one another and customers arrive to join the queue that offer services that they need. The mathematical model was developed assuming an M/M/1 queue system and the measures of effectiveness were derived. The model was applied to solve the problem of customer congestion in a restaurant in the city of Ibadan, Nigeria that serves three different local delicacies. The three local delicacies constitute three different queues at the first stage. The second stage consists of only one queue which is for purchase of drinks and the third stage which is the last stage is for payment. Every customer in the restaurant passes through the three stages. Utilization factors for the five queues were determined and found to range from 70% to 97%. The average time spent by customers in the system was found to be 543.04 minutes. A simulation study using what-if scenario analysis was performed to determine the optimum service configuration for the system. The optimum configuration reduced average time for customers in the system from 543.04 minutes to 13.47 minutes without hiring new servers.

High Throughput Scheduling Algorithms for Input Queued Packet Switches

The high-performance computing paradigm needs high-speed switching fabrics to meet the heavy traffic generated by their applications.These switching fabrics are efficiently driven by the deployed scheduling algorithms.In this paper,we proposed two scheduling algorithms for input queued switches whose operations are based on ranking procedures.At first,we proposed a Simple 2-Bit(S2B)scheme which uses binary ranking procedure and queue size for scheduling the packets.Here,the Virtual Output Queue(VOQ)set with maximum number of empty queues receives higher rank than other VOQ’s.Through simulation,we showed S2B has better throughput performance than Highest Ranking First(HRF)arbitration under uniform,and non-uniform traffic patterns.To further improve the throughput-delay performance,an Enhanced 2-Bit(E2B)approach is proposed.This approach adopts an integer representation for rank,which is the number of empty queues in a VOQ set.The simulation result shows E2B outperforms S2B and HRF scheduling algorithms with maximum throughput-delay performance.Furthermore,the algorithms are simulated under hotspot traffic and E2B proves to be more efficient.

Active Queue Management技术的研究与发展

Active Queue Management(AQM)技术通过有效控制输出队列的丢包时间和丢包方式,对拥塞进行早期通告,这在TCP拥塞控制的实现中至关重要。目前对AQM进行较全面介绍和总结的文献尚不多见,以RandomEarly Detection(RED)为重点介绍了这种第一代AQM技术的设计思想、优缺点以及为此出现的多种RED变种方法,另外还简单介绍了其它几种与RED设计思路不同的AQM方法,以期对AQM技术的研究和发展进行较全面的总结,并促进国内学者以及设备制造商对这一技术的关注。

Analytical Modeling of a Multi-queue Nodes Network Router

This paper presents the derivation of an analytical model for a multi-queue nodes network router, which is referred to as the multi-queue nodes （mQN） model. In this model, expressions are derived to calculate two performance metrics, namely, the queue node and system utilization factors. In order to demonstrate the flexibility and effectiveness of the mQN model in analyzing the performance of an mQN network router, two scenarios are performed. These scenarios investigated the variation of queue nodes and system utilization factors against queue nodes dropping probability for various system sizes and packets arrival routing probabilities. The performed scenarios demonstrated that the mQN analytical model is more flexible and effective when compared with experimental tests and computer simulations in assessing the performance of an mQN network router.

A Non-Preemptive Priority Queueing System with a Single Server Serving Two Queues M/G/1 and M/D/1 with Optional Server Vacations Based on Exhaustive Service of the Priority Units

We study a vacation queueing system with a single server simultaneously dealing with an M/G/1 and an M/D/1 queue. Two classes of units, priority and non-priority, arrive at the system in two independent Poisson streams. Under a non-preemptive priority rule, the server provides a general service to the priority units and a deterministic service to the non-priority units. We further assume that the server may take a vacation of random length just after serving the last priority unit present in the system. We obtain steady state queue size distribution at a random epoch. Corresponding results for some special cases, including the known results of the M/G/1 and the M/D/1 queues, have been derived.

Development and Investigation of the Program Model of Multichannel Queueing System with Unreliable Recoverable Servers in Matlab Environment

In real life, in different industries, we often deal with systems designed for multiple use for performing single-type tasks. Processes taking place at this time are called service of requirements, and the systems themselves—Queueing Systems. This article is dedicated to computer software modelling of processes taking place in the systems in question, Markov processes in particular. In this article, by means of Matlab environment, software realization of one of the typical models of queueing service theory-multichannel QS with unreliable recoverable servers and limited number of requirements in the system, is fulfilled. The results of this research are important because it gives the possibility to use received results to determine optimality degree of some real queueing systems that possess Markov property.

Basic Limit Theorems for Light Traffic Queues &Their Applications

In this paper, we study some basic limit theorems characterizing the stationary behavior of light traffic queuing systems. Beginning with limit theorems for the simple M/M/1 queuing system, we demonstrate the methodology for applying these theorems for the benefit of service systems. The limit theorems studied here are dominant in the literature. Our contribution is primarily on the analysis leading to the application of these theorems in various problem situations for better operations. Relevant Examples are included to aid the application of the results studied in this work.

基于优先级的Three-Queue调度算法研究

针对Hadoop平台上调度算法存在的不足,提出了一种改进的调度算法———Triple-Queue算法。在充分考虑数据的本地性后,Triple-Queue算法设计了一种改进的优先级计算模型,以有效地区分用户作业的等级,同时又保证一定程度的公平性,进而减小作业执行时间,避免系统资源浪费。实验结果表明,随着数据量的提高,该算法执行效率明显提高,同时能够较好地解决数据本地性问题。

基于IP Queue的实时网页过滤系统的设计与实现

在分析了IP Queue机制的实现技术、HTTP请求报文和响应报文,以及IP数据包的相关特征的基础上,实现了基于IP地址、URL的请求报文过滤以及基于关键词的响应报文过滤的实时网页过滤系统。该系统同时运行于一个具体的网关计费系统,提高了网关的监控能力,为增强同类产品的网络安全尤其是在用户态防火墙和网关监控等方面提供了有益的参考。

THE TRANSIENT SOLUTION FOR M/G/1 QUEUEWITH SERVER VACATIONS

In this paper, the transient solutions for M/G/1 queues with single server vacation and multiple server vacations are firstly studied, and the recursion expressions of their Laplace transform are given. Further the distribution and stochastic decomposition result of the queue length at a random point in equilibrium are directly obtained from the transient solution. As will be seen this paper provides a intuitive and elegant method for studying transient solutions for M/G/1 queues with single server.

Tele-Network Design Based on Queue Competition Algorithm

In this paper, we report research on how to design the tele-network. First of all, we defined the reliability of tele-network. According to the definition, we divide the whole reliability into two parts:the reliability of the mini-way and that of the whole system. Then we do algebra unintersection of the mini-way, deriving a function of reliability of tele-network. Also, we got a function of the cost of tele-network after analyzing the cost of arcs and points. Finally, we give a mathematical model to design a tele-network. For the algorithm, we define the distance of a network and adjacent area within certain boundaries . We present a new algorithm--Queue Competition Algorithm (QCA) based on the adjacent area . The QCA correlates sequence of fitnesses in their father-generations with hunting zone of mutation and the number of individuals generated by mutation, making the stronger fitness in a small zone converge at a local extreme value, but the weaker one takes the advantage of lots of individuals and a big zone to hunt a new local extreme value. In this way, we get the overall extreme value. Numerical simulation shows that we can get the efficient hunting and exact solution by using QCA. The QCA efficient hunting and exact solution.

基于Netfilter框架和IP Queue机制的轻量级网络防火墙实现

一般而言,要在Linux下开发防火墙的程序,需要对内核协议栈有深入的理解,并掌握内核协议栈代码的细节。这对普通开发者是非常有难度的。Netfilter是一个支持数据报过滤、数据报处理、NAT等功能的内核子系统框架。以Linux 2.6内核为基础。IP Queue机制是Linux内核在Netfilter框架的基础上提供的,是应用层上的机制,通过NetLink和内核进行交互,这使得开发一些用户态的防火墙应用成为可能。在此基础上,同时实现了一种基于Netfilter框架和IP Queue机制的轻量级防火墙。通过对比测试表明,由于设计清晰的模块架构、较强的可扩展性,本文实现的轻量级防火墙能够很好地达到实际要求,容易开发出更专业防火墙程序。

Cycle-by-Cycle Queue Length Estimation for Signalized Intersections Using Multi-Source Data

In order to estimate vehicular queue length at signalized intersections accurately and overcome the shortcomings and restrictions of existing studies especially those based on shockwave theory,a new methodology is presented for estimating vehicular queue length using data from both point detectors and probe vehicles. The methodology applies the shockwave theory to model queue evolution over time and space. Using probe vehicle locations and times as well as point detector measured traffic states,analytical formulations for calculating the maximum and minimum( residual) queue length are developed. The proposed methodology is verified using ground truth data collected from numerical experiments conducted in Shanghai,China. It is found that the methodology has a mean absolute percentage error of 17. 09%,which is reasonably effective in estimating the queue length at traffic signalized intersections. Limitations of the proposed models and algorithms are also discussed in the paper.

TRANSIENT SOLUTION FOR QUEUE-LENGTH DISTRIBUTION OF Geometry/G/1 QUEUEING MODEL

In this paper, the Geometry/G/1 queueing model with inter-arrival times generated by a geometric（parameter p） distribution according to a late arrival system with delayed access and service times independently distributed with distribution {gj }, j≥ 1 is studied. By a simple method （techniques of probability decomposition, renewal process theory） that is different from the techniques used by Hunter（1983）, the transient property of the queue with initial state i（i ≥ 0） is discussed. The recursion expression for u -transform of transient queue-length distribution at any time point n^＋ is obtained, and the recursion expression of the limiting queue length distribution is also obtained.