Performance Comparison of Active Queue Management Techniques
T. B. Reddy
2008-01-01
Full Text Available Congestion is an important issue which researchers focus on in the Transmission Control Protocol (TCP network environment. To keep the stability of the whole network, congestion control algorithms have been extensively studied. Queue management method employed by the routers is one of the important issues in the congestion control study. Active Queue Management (AQM has been proposed as a router-based mechanism for early detection of congestion inside the network. In this study, we are comparing AQM two popular queue management methods, Random Early Detection (RED and droptail, in different aspects, such as throughput and fairness Index. The comparison results indicate RED performed slightly better with higher throughput and higher fairness Index than droptail. Simulation is done by using Network Simulator (NS2 and the graphs are drawn using X- graph.
SAM: Support Vector Machine Based Active Queue Management
Recent years have seen an increasing interest in the design of AQM (Active Queue Management) controllers. The purpose of these controllers is to manage the network congestion under varying loads, link delays and bandwidth. In this paper, a new AQM controller is proposed which is trained by using the SVM (Support Vector Machine) with the RBF (Radial Basis Function) kernal. The proposed controller is called the support vector based AQM (SAM) controller. The performance of the proposed controller has been compared with three conventional AQM controllers, namely the Random Early Detection, Blue and Proportional Plus Integral Controller. The preliminary simulation studies show that the performance of the proposed controller is comparable to the conventional controllers. However, the proposed controller is more efficient in controlling the queue size than the conventional controllers. (author)
WSAP: provide loss rate differentiation with active queue management
Zhang Miao; Wu Jianping; Xu Ke
2005-01-01
How to provide service differentiation in the Internet is a hot research topic. One proposal is to provide loss rate differentiation by assigning levels of dropprecedence to IP packets. This paper proposes a new Active Queue Management (AQM) mechanism, Weighted SAP (WSAP) to achieve this goal. WSAP is based on a new AQM algorithm called Simple Adaptive Proportional (SAP). WSAP can approximate proportional loss rate differentiation, while keeping high link utilization and short queuing delay. Compared with Weighted RED(WRED) and RED In and Out (RIO), WSAP is easier to configure and can provide better performance. Furthermore, an architecture for differentiated service is proposed. In the design of this architecture, more attention is paid to the characte of network traffic in the Internet and an attempt is made to preserve the Internet's oringinal design principles.
A FUZZY-LOGIC CONTROL ALGORITHM FOR ACTIVE QUEUE MANAGEMENT IN IP NETWORKS
无
2008-01-01
Active Queue Management (AQM) is an active research area in the Internet community. Random Early Detection (RED) is a typical AQM algorithm, but it is known that it is difficult to configure its parameters and its average queue length is closely related to the load level. This paper proposes an effective fuzzy congestion control algorithm based on fuzzy logic which uses the predominance of fuzzy logic to deal with uncertain events. The main advantage of this new congestion control algorithm is that it discards the packet dropping mechanism of RED, and calculates packet loss according to a preconfigured fuzzy logic by using the queue length and the buffer usage ratio. Theoretical analysis and Network Simulator (NS) simulation results show that the proposed algorithm achieves more throughput and more stable queue length than traditional schemes. It really improves a router's ability in network congestion control in IP network.
Nguyen Kim Quoc
2015-08-01
Full Text Available The bottleneck control by active queue management mechanisms at network nodes is essential. In recent years, some researchers have used fuzzy argument to improve the active queue management mechanisms to enhance the network performance. However, the projects using the fuzzy controller depend heavily on professionals and their parameters cannot be updated according to changes in the network, so the effectiveness of this mechanism is not high. Therefore, we propose a model combining the fuzzy controller with neural network (FNN to overcome the limitations above. Results of the training of the neural networks will find the optimal parameters for the adaptive fuzzy controller well to changes of the network. This improves the operational efficiency of the active queue management mechanisms at network nodes.
Processor Based Active Queue Management for providing QoS in Multimedia Application
Selvam, N Saravana
2010-01-01
The objective of this paper is to implement the Active Network based Active Queue Management Technique for providing Quality of Service (QoS) using Network Processor(NP) based router to enhance multimedia applications. The performance is evaluated using Intel IXP2400 NP Simulator. The results demonstrate that, Active Network based Active Queue Management has better performance than RED algorithm in case of congestion and is well suited to achieve high speed packet classification to support multimedia applications with minimum delay and Queue loss. Using simulation, we show that the proposed system can provide assurance for prioritized flows with improved network utilization where bandwidth is shared among the flows according to the levels of priority. We first analyze the feasibility and optimality of the load distribution schemes and then present separate solutions for non-delay sensitive streams and delay-sensitive streams. Rigorous simulations and experiments have been carried out to evaluate the performan...
A GA-based PID active queue management control design for TCP/IP networks
In this paper, a genetic algorithm-based (GA-based) proportional-integral-derivative (PID) controller as an active queue manager for Internet routers is proposed to reduce packet loss and improve network utilization in TCP/IP networks. Based on the window-based nonlinear dynamics, the TCP network was modeled as a time-delayed system with a saturated input due to the limitations of packet-dropping probability and the effects of propagation delays in TCP networks. An improved genetic algorithm is employed to derive optimal or near optimal PID control gains such that a performance index of integrated-absolute error (IAE) in terms of the error between the router queue length and the desired queue length is minimized. The performance of the proposed control scheme was evaluated in various network scenarios via a series of numerical simulations. The simulation results confirm that the proposed scheme outperforms other AQM schemes
An Active Queue Management for QoS Guarantee of the High Priority Service Class
Kim, Hyun Jong; Shim, Jae Chan; Kim, Hwa-Suk; Cho, Kee Seong; Choi, Seong Gon
In this paper, we propose the active queue management mechanism (Active-WRED) for guaranteeing the quality of the high priority service class (VoIP or IPTV) in the multi-class traffic service environment. In the congestion situation, this mechanism increases the drop probability of the low priority traffic and reduces the drop probability of the high priority traffic; therefore it can guarantee the quality of the high priority service class from the poor quality by the packet loss.
Multicast Services of QoS-Aware Active Queue Management over IP Multimedia Applications
Hwang, I.-Shyan; Hwang, Bor-Jiunn; Chang, Pen-Ming
2010-10-01
Recently, the multimedia services such as IPTV, video conference emerges to be the main traffic source. When UDP coexists with TCP, it induces not only congestion collapse but also unfairness problem. In this paper, a new Active Queue Management (AQM) algorithm, called Traffic Sensitive Active Queue Management (TSAQM), is proposed for providing multimedia services. The TSAQM comprise Dynamic Weight Allocate Scheme (DWAS) and Service Guarantee Scheme (SGS), the purpose of DWAS is to allocate resource with fairness and high end-user utility, and the purpose of SGS is to determine the satisfactory threshold (TH) and threshold region (TR). Several objectives of this proposed scheme include achieving high end-user utility for video service, considering the multicast as well as unicast proprieties to meet inter-class fairness and achieving the QoS requirement by adjusting the thresholds adaptively based on traffic situations.
On the basis of variable structure control (VSC), an active queue management (AQM) controller is presented for a class of TCP communication networks. In the TCP/IP networks, the packet drop probability is limited between 0 and 1. Therefore, we modeled TCP/AQM as a rate-based non-linear system with a saturated input. The objective of the VSC-based AQM controller is to achieve the desired queue size and to guarantee the asymptotic stability of the closed-loop TCP non-linear system with saturated input. The performance and effectiveness of the proposed control law are then validated for different network scenarios through numerical simulations in both MATLAB and Network Simulator-2 (NS-2). Both sets of simulation results have confirmed that the proposed scheme outperforms other AQM schemes.
Chen, C.-K. [Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan (China); Liao, T.-L. [Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan (China)], E-mail: tlliao@mail.ncku.edu; Yan, J.-J. [Department of Computer and Communication, Shu-Te University, Kaohsiung 824, Taiwan (China)
2009-04-15
On the basis of variable structure control (VSC), an active queue management (AQM) controller is presented for a class of TCP communication networks. In the TCP/IP networks, the packet drop probability is limited between 0 and 1. Therefore, we modeled TCP/AQM as a rate-based non-linear system with a saturated input. The objective of the VSC-based AQM controller is to achieve the desired queue size and to guarantee the asymptotic stability of the closed-loop TCP non-linear system with saturated input. The performance and effectiveness of the proposed control law are then validated for different network scenarios through numerical simulations in both MATLAB and Network Simulator-2 (NS-2). Both sets of simulation results have confirmed that the proposed scheme outperforms other AQM schemes.
ANALYTICAL CHARACTERIZATION OF WLANS FOR QUALITY-OF-SERVICE WITH ACTIVE QUEUE MANAGEMENT
M. Usha
2014-09-01
Full Text Available Design of an Active Queue Management scheme at the Access Point to address the problem of congestion control, packet delay variation and packet loss rate is discussed. The proposed mechanism calculates and adjusts redundancy rate adaptively at the access point by considering both network traffic load and wireless channel condition. Real-time applications such as Mobile learning and smart learning need the special treatment and require differentiated QoS to satisfy the client who is ready to pay more than others. Maintaining the jitter value of the multimedia packets below the threshold is essential to guarantee the desirable quality of the video at the receiver. The work initially concentrates on minimizing the packet loss of such priority flows and they have to be given place in the queue even at the time of buffer overflow. Thus the proposed work uses push-out policy to provide differentiated services to the multimedia flow which achieves considerable improvement in the video quality at the receiver. The considerable decrease in packet loss rate and special treatment in the queue of the access point lowers the packet delay variation of the multimedia flow. The results show that the AQM used at the access point effectively achieves low packet loss, low jitter using differentiated FEC rate calculation without generating congestion in the wireless network.
Predictive functional control for active queue management in congested TCP/IP networks.
Bigdeli, N; Haeri, M
2009-01-01
Predictive functional control (PFC) as a new active queue management (AQM) method in dynamic TCP networks supporting explicit congestion notification (ECN) is proposed. The ability of the controller in handling system delay along with its simplicity and low computational load makes PFC a privileged AQM method in the high speed networks. Besides, considering the disturbance term (which represents model/process mismatches, external disturbances, and existing noise) in the control formulation adds some level of robustness into the PFC-AQM controller. This is an important and desired property in the control of dynamically-varying computer networks. In this paper, the controller is designed based on a small signal linearized fluid-flow model of the TCP/AQM networks. Then, closed-loop transfer function representation of the system is derived to analyze the robustness with respect to the network and controller parameters. The analytical as well as the packet-level ns-2 simulation results show the out-performance of the developed controller for both queue regulation and resource utilization. Fast response, low queue fluctuations (and consequently low delay jitter), high link utilization, good disturbance rejection, scalability, and low packet marking probability are other features of the developed method with respect to other well-known AQM methods such as RED, PI, and REM which are also simulated for comparison. PMID:18995853
Optimal Tracking Controller Design for Active Queue Management Routers via LQ-Servo
Lee, Kang Min; Yang, Ji Hoon; Suh, Byung Suhl
2009-01-01
This paper proposes the LQ-Servo controller for AQM (Active Queue Management) routers. The proposed controller structure is made by taking a traditional servo mechanism based on Linear Quadratic approach and by augmenting a new state variable to the feed forward loop. Since the controller structure is consists of a standard optimal feedback regulator and a feed forward controller, it is able to enhance the usefulness of resources and to reduce unnecessary memory reservations such as RAM (Random Access Memory) or SMA (Shared Memory Area) on ordinary router systems, respectively.
QoS-Aware Active Queue Management for Multimedia Services over the Internet
Hwang I-Shyan
2011-01-01
Full Text Available Recently, with multimedia services such as IPTV, video conferencing has emerged as a main traffic source. When UDP coexists with TCP, it induces not only congestion collapse but also an unfairness problem. In this paper, a new Active Queue Management algorithm, called Traffic Sensitive Active Queue Management (TSAQM, is proposed for providing multimedia services in routers. The TSAQM is comprised of Dynamic Weight Allocate Scheme (DWAS and Service Guarantee Scheme (SGS. The purpose of DWAS is to fairly allocate resources with high end-user utility, and the SGS is to determine the satisfactory threshold (TH and threshold region (TR. Besides, a multiqueue design for different priority traffic, and threshold TH and threshold region TR is proposed to achieve the different QoS requirements. Several objectives of this proposed scheme include achieving high end user utility for video services, considering the multicast as well as unicast proprieties to meet interclass fairness, and achieving the QoS requirement by adaptively adjusting the thresholds based on the traffic situations. Performance comparisons with the GRED-I are in terms of packet dropping rate and throughput to highlight the better behavior of the proposed schemes due to taking into account the fairness and different weights for video layers.
Managing Network Congestion with a Modified Kohonen-based RED Queue
Maria Priscilla,
2010-11-01
Full Text Available The robustness of today’s Internet depends heavily on the TCP congestion control mechanism. Congestion is a key factor in transmission control protocol (TCP which leads to many researches. Congestion control techniques are extensively used in order to maintain the stability and reliability of the network. One of theimportant issues in the congestion control study is the Queue management technique employed by the network. An exponential increase in network traffic causes increasing packet loss rates. So, the IETF is considering the deployment of active queue management techniques to stem the increasing packet loss rates. Even though the packet loss rates are reduced in the internet by means of active queue management, the prevention of high loss rates is still a major concern for the present techniques. The severity of congestion is indicated by the queue lengths which is the main problem in the present queue management algorithms. Therefore, a fundamentally different active queue management algorithm called Random Early Detection (RED is proposed to overcome the above mentioned problem. BLUE uses packet loss and link idle events to manage congestion. Usingsimulation and controlled experiments, RED is shown to perform significantly better than other techniques both in terms of packet loss rates and buffer size requirements in the network. Then RED approach is combined with Kohonen technique that enables a stable queue length without complex parameters setting and passive measurements. This paper extends the Kohonen RED technique with the modified Kohonen based RED queue technique. It is clearly observed from the experimental results that the proposed approach provides better recognition accuracy with very low training time.
Comparison of TEAR and TFRC throughput for Drop tail and RED Queue Management Techniques
Parminderjeet Singh
2014-12-01
Full Text Available The comparison of throughput for TEAR (TCP emulation at receivers and TFRC TCP friendly rate control in MANETs is done with varying Active queue Management Techniques. The analysis reveals that for bandwidth constraint links, TEAR and TFRC perform far better than normal traffic propagation through TCP. In case of TEAR, the processing and route congestion algorithm load is shared by the receiver resulting in lesser load at the transmitters. In TFRC the TCP traffic is propagated via an algorithm to curb acknowledgement congestions. The effect of these two techniques is monitored on Droptail and RED, two of the most common Active Queue Management Techniques.
FastQueue:A High Performance Disk Queue Storage Management Mechanism%FastQueue:一种高性能的磁盘队列存储管理机制
魏青松; 卢显良; 周旭
2003-01-01
High reliability is the primary requirement for messaging system. Messaging system always utilizes disk queue to temporarily store message to be delivered. Experiments show that Disk queue I/O is the primary performance bottleneck in the messaging system. In this paper we present a high performance disk queue storage management mechanism-FastQueue. The FastQueue utilizes a large file to serve as disk queue to reduce file manage overhead, in which adjacent messages are stored in adjacent disk block. Several messages are written to disk queue in a one large write by Lazy Gathering Write. Several adjacent messages are read into buffer in a one read by Sequential Grouping Prcfetch. The Lazy Gathering Write and Sequential Grouping Prefetch policies take full advantage of the disk bandwidth. Experiment shows that performance of the FastQueue is more than an order of magnitude higher than that of traditional disk queue.
叶成荫
2011-01-01
For the problem of congestion control in the Internet, a novel active queue management ( AQM ) algorithm based on the sliding mode control theory is proposed. Considering UDP flow, an active queue management algorithm based on adaptive global sliding mode control is designed. The algorithm guarantees the network system robustness during the whole control process and uses RBF neural netword as adaptive law to eliminate the effect from the disturbance of UDP flow. Simulation results demonstrate that the algorithm enables the queue length to converge to set value quickly,keeps the small queue oscillation, and outperforms the conventional IP control and sliding mode control.%针对TCP网络的拥塞控制问题,采用滑模控制理论提出了一种新的主动队列管理算法.考虑到UDP流干扰的情况,设计了基于自适应全局滑模控制的主动队列管理算法.该算法保证网络系统在整个控制过程中的鲁棒性,并且使用RBF神经网络作为自适应律来消除UDP流干扰对系统的影响.仿真结果表明该算法可以使队列长度快速收敛到设定值,同时维持较小的队列振荡,优于传统的PI控制和滑模控制.
Adaptive Queue Management with Restraint on Non-Responsive Flows
Lan Li
2003-12-01
Full Text Available This paper proposes an adaptive queue management scheme (adaptive RED to improve Random Early Detection (RED on restraining non-responsive flows. Due to a lack of flow control mechanism, non-responsive flows can starve responsive flows for buffer and bandwidth at the gateway. In order to solve the disproportionate resource problem, RED framework is modified in this way: on detecting when the non-responsive flows starve the queue, packet-drop intensity (Max_p in RED can be adaptively adjusted to curb non-responsive flows for resource fair-sharing, such as buffer and bandwidth fair-sharing. Based on detection of traffic behaviors, intentionally restraining nonresponsive flows is to increase the throughput and decrease the drop rate of responsive flows. Our experimental results based on adaptive RED shows that the enhancement of responsive traffic and the better sharing of buffer and bandwidth can be achieved under a variety of traffic scenarios.
V.Sinthu Janita Prakash
2012-10-01
Full Text Available Wireless links are characterized by high error rates and intermittent connectivity. TCP congestion control has been developed on the assumption that network congestion is the only cause for packet loss. Upon detecting a packet loss, TCP drops its transmit window resulting in an unnecessary reduction of end-to-end throughput which results in suboptimal performance.The sender has to be made aware by some feedback mechanism that some of the losses reported are not due to congestion. The Active Queue Management algorithms (AQM are used to reduce congestion, and in this paper, we have analysed four AQM algorithms, Random Early Deduction (RED, Wireless Explicit Congestion Notification (WECN, Queue Management Backward Congestion Control Algorithm (QMBCCA and its enhanced version Extended Queue Management Backward Congestion Control Algorithm (EQMBCCA. WECN, QMBCCA & EQMBCCA algorithms make use of feedback mechanisms. WECN gives feedback using the CE bit. QMBCCA and EQMBCCA make use of ISQ notifications and also the CE bit whenever the average queue size crosses minimum threshold value. EQMBCCA reduces the reverse ISQ traffic by introducing a configurable intermediate threshold value IntThres. The comparison is made in terms of Delay, HTTP packet loss percentage and fairness for FTP flows in a wireless environment. It is found that the performance of EQMBCCA is almost equal to that of QMBCCA and better than RED and WECN.
基于内模控制的自适应主动队列管理算法%Adaptive active queue management algorithm based on internal model control
林开司; 林开武; 张露
2011-01-01
实际网络具有大时滞性和动态特性.针对大时滞特性,根据内模控制( IMC)和改进的TCP/AQM控制理论模型设计了一种适合于大延时网络环境的主动队列管理算法.而对于网络的动态特性,分析了网络参数的变化给算法带来的影响,并以此对算法参数进行在线修正,得到符合大时滞网络的自适应AQM算法.最后通过NS2仿真实验验证了设计的AQM算法的可靠性.%Real networks are of large delay and dynamics. According to the IMC (Internal Model Control) and improved control theory model with TCP/AQM, an active queue management algorithm suitable for the large delay network environment was designed to cope with the large delays. For the dynamics of the networks, the impact that the change of network parameter brings to the algorithm was analyzed to correct the algorithm parameter online. The adaptive active queue management algorithm suitable for the large delay network was acquired. The reliability of the algorithm has been verified by NS2 simulation.
周川; 何俊伟; 陈庆伟
2013-01-01
Considering the problem of congestion control for the time-varying and uncertain TCP/IP network, we proposed a novel discrete-time robust active queue management (AQM) scheme based on H-infinity feedback control for the TCP flow model with link capacity disturbance and parameter uncertainties simultaneously. In this method, the bandwidth occupied by short-lived connections is treated as the external disturbances, and the effect of both delay and parameter uncertainties is taken into account for the TCP/AQM system model. By using Lyapunov stability theory and LMI techniques, we propose a discrete-time robust H-infinity AQM controller to guarantee the asymptotic stability and robustness of the queue length response of a router queues. Finally the NS-2 simulation results demonstrate effectiveness of the proposed method.%针对TCP/IP网络存在参数时变和不确定性下的拥塞控制问题,提出一种新的基于H∞状态反馈控制的离散鲁棒主动列队管理算法(AQM).该方法针对不确定TCP流模型,将短期突发流所占据的带宽作为系统的外部干扰,同时考虑时滞和参数不确定性因素,基于Lyapunov稳定性理论和线性矩阵不等式技术,设计了离散鲁棒状态反馈控制器以保证路由器队列响应的稳定性和鲁棒性.最后,通过NS-2仿真验证了本文方法的有效性.
The Stability Studies of PSO-PID Active Queue Management in Wired Network%有线网络PSO-PID主动队列管理算法稳定性分析
孙慧玉; 姜文刚
2014-01-01
主动队列管理算法的稳定性是实现拥塞控制的基础，针对目前PID-AQM 控制器控制参数大多基于经验、缺乏稳定性分析的问题，提出了粒子群优化PID参数的整定策略，同时运用稳定分析论分析PSO-PID队列管理算法的稳定性。考虑TCP/AQM系统的时滞性，将时延系统利用泰勒展开转化为非时延系统进行稳定性判定。通过NS2仿真，结果表明，PSO-PID算法稳定性明显优于PID算法。%The stability of the active queue management is the basis of the congestion control ,most of the control parameters of the PID-AQM controller based on experience ,lack of stability analysis .In order to solve the problem , particle swarm optimize the PID parameters strategy was proposed ,while use the theory of stability to analysis the stability of the PSO-PID active queue management .Consider the TCP/AQM system delay ,the paper transfers the delay system into non-delay system by using Taylor series expansion .The NS2 simulation results the PSO-PID algorithm shows some advantages over the PID algorithm .
A Self-tuning Fuzzy Queue Management Algorithm for Congestion Control
Zhang Jingyuan(张敬辕); Xie Jianying
2004-01-01
This letter presents an effective self-tuning fuzzy queue management algorithm for congestion control. With the application of the algorithm, routers in IP network regulate its packet drop probability by a self-tuning fuzzy controller. The main advantage of the algorithm is that, with the parameter self-tuning mechanism, queue length can keep stable in a variety of network environments without the difficulty of parameter configuration. Simulations show that the algorithm is efficient, stable and outperforms the popular RED queue management algorithm significantly.
基于预测控制的时滞网络主动队列管理%Active queue management of delay network based on model predictive control
王萍; 陈虹; 卢晓晖
2011-01-01
针对Internet网络这种典型的延迟系统,基于模型预测控制理论,提出了一种新的主动队列管理算法——MPAQM算法.首先考虑时滞系统的因果性定义预测输出,根据预测模型和状态估计器,预测瓶颈链路队列的未来动态特性；然后将拥塞控制的控制要求转化为优化目标函数,求解优化问题得到丢包率.在单瓶颈和多瓶颈网络拓扑中进行仿真验证,结果显示MPAQM算法能快速平稳地收敛于队列长度的期望值,丢包率小且具有较好的稳定性和鲁棒性.%Based on the theory of model predictive control, a novel Active Queue Management (AQM) algorithm is proposed for typical Internet systems with large delay, called MPAQM. First, the predicted output is defined by considering the causality of time-delay system. Then, according to the predictive model and state estimator, the future dynamic queue length in data buffer is predicted. Finally, the control requirement of congestion is converted to optimal control objective function, and drop probability is obtained by solving the optimal problem. The performances of MPAQM are evaluated through a series of simulations in simulator NS2 with single and multiple-bottleneck network topologies. Simulation results show that the proposed MPAQM algorithm outperforms RED and PI algorithms in terms of stability, disturbance rejection and robustness.
V.SAVITHA
2012-08-01
Full Text Available At present there has been a tremendous growth in the computer networks and wireless networks. Due to the enormous growth of voice, audio, video and data applications over the wireless networks, therequirement of congestion control mechanism is also developing along with the development of wireless network applications. The congestion in the network has drastically affected the Quality of Service (QoSrequirements of the applications. Active Queue Management (AQM is the technique of signaling Transmission Control Protocol (TCP sources from middle routers and its major purpose is to lessen the congestion and also satisfy the QoS requirements. In this paper, Modified Robust Queue Management with Feedback Compensation Technique is proposed that helps to reduce the delay and low loss service. The proposed technique is based on feedback compensation technique and the algorithm used in this Modified RQM is called Modified Proportional Integral based series compensation, and Position feedback compensation (Modified PIP. The performance of Modified RQM with Feedback (MFPIP is evaluated against the existing RQM in terms of packet loss, queue size, unloaded buffer size, End-to-End delay, bandwidth utilization and jitter value. It is revealed from theresults that the Modified RQM with Feedback (MFPIP is more effective in handling the congestion control in Wireless Communication Networks.
Collaborative Virtual Queue: Fair Management of Congested Departure Operations and Benefit Analysis
Burgain, Pierrick; Clarke, John-Paul
2008-01-01
Due to the stochastic nature of departure operations, working at full capacity makes major US airports very sensitive to uncertainties. Consequently, airport ground operations face critically congested taxiways and long runway queues. In this report, we show how improved management of departure operations from the ready-to-push-back time to the wheels-off time can potentially yield significant benefits to airlines and air traffic services. We develop a Collaborative Virtual Queue to enable better optimization capabilities during congested situations while taking into account the laissez-faire competitive environment. Results are evaluated using a departure system model, validated using current statistics and previous studies. First, the Collaborative Virtual Queue enables keeping aircraft away from runway queues, which increases wheels-off time predictability. Second, holding aircraft enables last-minute intra-airline flight switching. This creates new optimization capabilities for airlines i.e. it gives airl...
Queue Management Practices of Quick ServiceRestaurants (QSR in Lipa City, Philippines
Leoven A. Austria
2015-12-01
Full Text Available –Problems regarding waiting line in quick service restaurants (QSR has been one of the main concerns of industries and scholars nowadays. It is because people today demand not only for qualityfood but also for speed. Quick service restaurant players explore on the approaches to optimize the efficiency of restaurant management. One important area that defines how well and efficient a fast food restaurant delivers its product and services to customers is its waiting line (queue management practices. The study was conducted at Lipa City, involving five popular quick service restaurants named by the researcher as QSR A, B, C, D, and E. It made used of 363customer respondents proportionally obtained from five restaurants.It intended to assess the extent of implementation of the queue management practices of the restaurants and the level of satisfaction of the customers in such practices in terms of customer arrival, waiting line and service facility. The findings revealed the queuing system used and the waiting line structured utilized by the restaurants. The extent of implementation of the queue management practices in the three areas mentioned of the five QSR’s was presented comparatively. Likewise, the level of customer’s satisfaction on the queue management practices was also determined. Significant difference in the extent of implementation and in the level of customer satisfaction were determined if the respondents were grouped according to restaurant’s profile. Recommendations in the improvement of queue were given based on the findings.
MULTIPATH VIRTUAL QUEUE MANAGEMENT SYSTEM FOR EFFECTIVE PACKET SCHEDULING IN MPLS NETWORKS
V. Ramachandran
2012-09-01
Full Text Available With the rapid development of communication and networking technologies VOIP has become an alternate to traditional telephony. These applications prefer timeliness in packet delivery. To perform load balancing, link utilization and to minimize the packet loss rate Multipath virtual Queue Management System for Effective Packet Scheduling in MPLS networks is proposed. The VoIP flows are dispersed into multiple available label switched paths to perform load balancing and link utilization. Virtual queues are maintained in all output ports to avoid queuing delay and HOL blocking. The proposed system ensures the arrival order of all the packets and plays back in the order of transmission. The performance of the proposed Virtual queuing system is compared with single path CSFQ queuing system with no virtual queue and Simulation results are proposed to show theefficiency of the proposed system.
陈亮; 张宏
2011-01-01
主动队列管理（AQM）通常研究队列控制器的设计．作为被控对象，传输控制协议（TCP）往往利用网络仿真器（NS）的仿真实现，因此有必要研究无线自组网的TCP及AQM特性．基于TCP窗口加性增一乘性减算法及排队原理，推导了TCP窗口及队列的微分方程，再基于比例积分AQM控制，推导了拥塞丢弃概率的微分方程，通过建立联立微分方程组，提出了AdHoc网络TCP／AQM微分模型．对比仿真显示，新模型能较好地估计无线白组网的性能．模型研究也表明，网络跳数，无线丢失和过小的队列成为AQM性能瓶颈，队列信息则有助于TCP区%The active queue management（AQM） is usually concerned with the queue controller design. As a controlled object, the transmission control protocol（TCP） is often realized by the simulation of Network Simulator（NS）. Thus, it is necessary to study the characteristics of TCP and AQM in Ad Hoc network. Differential equations for the TCP window- size and queue-length are developed based on the TCP window additive-increase multiplicative-decrease algorithm and the queuing principle. Next, the differential equation of the congestion-loss probability is derived based on the proportional- integral AQM control. Then, the Ad I-Ioc network TCP/AQM differential model is proposed through the simultaneous differential equations. The comparison simulations show that the new model can estimate Ad Hoe network performance. The model research also shows that the number of hops, wireless loss and the very small queue become the bottleneck of the AQM performances. Furthermore, the queue information can help TCP discriminate between congestion loss and wireless loss in Ad Hoc network.
A queueing model of pilot decision making in a multi-task flight management situation
Walden, R. S.; Rouse, W. B.
1977-01-01
Allocation of decision making responsibility between pilot and computer is considered and a flight management task, designed for the study of pilot-computer interaction, is discussed. A queueing theory model of pilot decision making in this multi-task, control and monitoring situation is presented. An experimental investigation of pilot decision making and the resulting model parameters are discussed.
DROP TAIL AND RED QUEUE MANAGEMENT WITH SMALL BUFFERS:STABILITY AND HOPF BIFURCATION
Ganesh Patil
2011-06-01
Full Text Available There are many factors that are important in the design of queue management schemes for routers in the Internet: for example, queuing delay, link utilization, packet loss, energy consumption and the impact of router buffer size. By considering a fluid model for the congestion avoidance phase of Additive Increase Multiplicative Decrease (AIMD TCP, in a small buffer regime, we argue that stability should also be a desirable feature for network performance. The queue management schemes we study are Drop Tail and Random Early Detection (RED. For Drop Tail, the analytical arguments are based on local stability and bifurcation theory. As the buffer size acts as a bifurcation parameter, variations in it can readily lead to the emergence of limit cycles. We then present NS2 simulations to study the effect of changing buffer size on queue dynamics, utilization, window size and packet loss for three different flow scenarios. The simulations corroborate the analysis which highlights that performance is coupled with the notion of stability. Our work suggests that, in a small buffer regime, a simple Drop Tail queue management serves to enhance stability and appears preferable to the much studied RED scheme.
BOB-RED queue management for IEEE 802.15.4 wireless sensor networks
Wu Jean-Lien
2011-01-01
Full Text Available Abstract Multimedia services over resource constrained wireless sensor networks (WSNs face a performance bottleneck issue from the gateway node to the sink node. Therefore, the queue management at the gateway node is crucial for diversified messages conveyed from the front nodes to the sink node. In this article, beacon order-based random early detection (BOB-RED queue management is proposed. BOB-RED is a dynamic adaptation scheme based on adjusting beacon interval and superframe duration in the IEEE 802.15.4 MAC superframe accompanied with RED queue management scheme to increase the transmission efficiency of multimedia over WSNs. We focus on the performance improvement upon different traffic loads over WSNs. Evaluation metrics include end-to-end delay, packet delivery ratio, and energy consumption in IEEE 802.15.4 beacon enabled mode. Simulation results show that BOB-RED can effectively decrease end-to-end delay and energy consumption compared to the DropTail scheme.
RED-DTB： A Dual Token Bucket Based Queue Management Algorithm
YinJian-hua; CaoYang; LingJun; HuangTian-xi
2003-01-01
Improving the Quality of Service (QoS) of Internet traffic is widely recognized as a critical issue for the next-generation networks. In this paper,we present a new algorithm for the active queue management, namely RED-DTB. This buffer control technique is used to enforce approximate fairness among a large number of concurrent Internet flows. Like RED (Random Early Detection) algorithm, the RED-DTB mechanism can be deployed to actively respond to the gateway congestion, keep the gateway in a healthy state, and protect the fragile flows from being stolen bandwidth by greedy ones. The algorithm is based on the so-called Dual Token Bucket (DTB) pattern. That is, on the one hand, every flow is rate-limited by its own token bucket, to ensure that it can not consume more than its fair share of bandwidth; On the other hand,to make some compensations to less aggressive flows, such as connections with larger round trip time or smaller sending window, and to gain a relatively higher system utilization coefficient, all flows, depending on their individual behavior, may have a chance to fetch tokens from the public token bucket when they run out of their own share of tokens. The algorithm is analyzed and evaluated by simulations, and is proved to be effective in protecting the gateway buffer and controlling the fair allocation of bandwidth among flows.
RED- DTB:A Dual Token Bucket Based Queue Management Algorithm
Yin Jian-hua; Cao Yang; Ling Jun; Huang Tian-xi
2003-01-01
Improving the Quality of Service (QoS) of Internet traffic is wide-ly recognized as a critical issue for the next-generation networks. In this paper,we present a new algorithm for the active queue management, namely RED-DTB. This buffer control technique is used to enforce approximate fairness among a large number of concurrent Internet flows. Like RED (Random Early Detection) algorithm, the RED-DTB mechanism can be deployed to actively re-spond to the gateway congestion, keep the gateway in a healthy state, and pro-tect the fragile flows from being stolen band width by greedy ones. The algo-rithm is based on the so-called Dual Token Bucket (DTB) pattern. That is, onthe one hand, every flow is rate-limited by its own token bucket, to ensure thatit can not consume more than its fair share of bandwidth; On the other hand,to make some compensations to less aggressive flows, such as connections with larger round trip time or smaller sending window, and to gain a relatively high-er system utilization coefficient, all flows, depending on their individual behav-ior, may have a chance to fetch tokens from the public token bucket when theyrun out of their own share of tokens. The algorithm is analyzed and evaluatedby simulations, and is proved to be effective in protecting the gateway bufferand controlling the fair allocation of bandwidth among flows.
李婷; 苗增强; 周玲; 满高华
2011-01-01
本文利用智能控制理论设计了针对大延时网络的单神经元-Smith AQM（Active Queue Management）算法。对算法的设计目标、参数整定规则等问题进行了深入研究,最后的仿真结果验证了该算法在大延时网络主动队列管理中的有效性。%This thesis designs a AQM algorithm based on intelligent control theory,which is single neurons-Smith AQM algorithm for large delay network.The design target and parameter adjusting rule of this algorithm are presented detailed in this thesis.The results
Analysing patient queue system in an imaging department: a step toward total quality management
Medical imaging has become an inevitable part of any diagnosis and/or management of the disease. This has put tremendous work-load on the medical imaging machines. The crowd of waiting patients at any busy imaging centre or rooms has become a common scene. This is especially true for any Government hospital or medical college in India since they cater to bulk of patients. As a part of total quality management we attempted to record, investigate, analyse and suggest on the state of patients' queue system at radiological imaging rooms
Method, apparatus and system for managing queue operations of a test bench environment
Ostler, Farrell Lynn
2016-07-19
Techniques and mechanisms for performing dequeue operations for agents of a test bench environment. In an embodiment, a first group of agents are each allocated a respective ripe reservation and a second set of agents are each allocated a respective unripe reservation. Over time, queue management logic allocates respective reservations to agents and variously changes one or more such reservations from unripe to ripe. In another embodiment, an order of servicing agents allocated unripe reservations is based on relative priorities of the unripe reservations with respect to one another. An order of servicing agents allocated ripe reservations is on a first come, first served basis.
WQM: An Aggregation-aware Queue Management Scheme for IEEE 802.11n based Networks
Showail, Ahmad
2014-08-17
Choosing the right buffer size in Wi-Fi networks is challenging due to the dynamic nature of the wireless environment. Over buffering or \\'bufferbloat\\' may produce unacceptable end-to-end delays, while static small buffers may limit the performance gains that can be achieved with various 802.11n enhancements, such as frame aggregation. We propose WQM, a queue management scheme customized for wireless networks. WQM adapts the buffer size based on measured link characteristics and network load. Furthermore, it accounts for aggregate length when deciding about the optimal buffer size. We implement WQM on Linux and evaluate it on a wireless testbed. WQM reduces the end-to-end delay by up to 8x compared to Linux default buffer size, and 2x compared to CoDel, the state-of-the-art bufferbloat solution, while achieving comparable network goodput. Further, WQM improves fairness as it limits the ability of a single flow to saturate the buffer.
Regulation of Queue Length in Router Based on an Optimal Scheme
Zhang, Nannan
2009-01-01
Based on the proportionally fair scheme that Kelly proposed to solve the optimization problems for utility function in networks, and in order to improve the congestion control performance for the queue in router, the linear and terminal sliding active queue management (AQM) algorithms are designed. Especially in the ter-minal sliding AQM algorithm, a special nonlinear terminal sliding surface is designed in order to force queue length to reach the desired value in finite time. The upper bound...
Ganesh, Ayalvadi; Wischik, Damon
2004-01-01
Big Queues aims to give a simple and elegant account of how large deviations theory can be applied to queueing problems. Large deviations theory is a collection of powerful results and general techniques for studying rare events, and has been applied to queueing problems in a variety of ways. The strengths of large deviations theory are these: it is powerful enough that one can answer many questions which are hard to answer otherwise, and it is general enough that one can draw broad conclusions without relying on special case calculations.
Palvannan, R Kannapiran; Teow, Kiok Liang
2012-04-01
Patient queues are prevalent in healthcare and wait time is one measure of access to care. We illustrate Queueing Theory-an analytical tool that has provided many insights to service providers when designing new service systems and managing existing ones. This established theory helps us to quantify the appropriate service capacity to meet the patient demand, balancing system utilization and the patient's wait time. It considers four key factors that affect the patient's wait time: average patient demand, average service rate and the variation in both. We illustrate four basic insights that will be useful for managers and doctors who manage healthcare delivery systems, at hospital or department level. Two examples from local hospitals are shown where we have used queueing models to estimate the service capacity and analyze the impact of capacity configurations, while considering the inherent variation in healthcare. PMID:20703697
Flow time analysis is a powerful concept to analyze the flow time of any arriving customer in any system at any instant. A load management mechanism can be employed very effectively in any queueing system by utilizing a system which provides probability of dual service rate. In this paper, we develop and demonstrate the flow and service processes transition diagram to determine the flow time of a customer in a load management late arrival state dependent finite discrete time queueing system with dual service rate where customers are hypo geometrically distributed. We compute the probability mass function of each starting state and total probability mass function. The obtained analytical results are validated with simulation results for varying values of arrival and service probabilities. (author)
Li, Jie; Li, Qiyue; Qu, Yugui; Zhao, Baohua
2011-01-01
Conventional MAC protocols for wireless sensor network perform poorly when faced with a delay-tolerant mobile network environment. Characterized by a highly dynamic and sparse topology, poor network connectivity as well as data delay-tolerance, delay-tolerant mobile sensor networks exacerbate the severe power constraints and memory limitations of nodes. This paper proposes an energy-efficient MAC protocol using dynamic queue management (EQ-MAC) for power saving and data queue management. Via data transfers initiated by the target sink and the use of a dynamic queue management strategy based on priority, EQ-MAC effectively avoids untargeted transfers, increases the chance of successful data transmission, and makes useful data reach the target terminal in a timely manner. Experimental results show that EQ-MAC has high energy efficiency in comparison with a conventional MAC protocol. It also achieves a 46% decrease in packet drop probability, 79% increase in system throughput, and 25% decrease in mean packet delay. PMID:22319385
Yugui Qu
2011-02-01
Full Text Available Conventional MAC protocols for wireless sensor network perform poorly when faced with a delay-tolerant mobile network environment. Characterized by a highly dynamic and sparse topology, poor network connectivity as well as data delay-tolerance, delay-tolerant mobile sensor networks exacerbate the severe power constraints and memory limitations of nodes. This paper proposes an energy-efficient MAC protocol using dynamic queue management (EQ-MAC for power saving and data queue management. Via data transfers initiated by the target sink and the use of a dynamic queue management strategy based on priority, EQ-MAC effectively avoids untargeted transfers, increases the chance of successful data transmission, and makes useful data reach the target terminal in a timely manner. Experimental results show that EQ-MAC has high energy efficiency in comparison with a conventional MAC protocol. It also achieves a 46% decrease in packet drop probability, 79% increase in system throughput, and 25% decrease in mean packet delay.
Resources Management in Active Networks
无
2003-01-01
In an active network, users can insert customized active codes into active nodes to execute. Thus it needs more resources than those required by conventional networks, and these resources must be effectively monitored and managed. Management policies in existing OSs are too complicated to apply to simple active packets. In this paper, we present new resources management policies that are mainly adoped to manage CPU, storage and transmission bandwidth. Namely, we use SPF algorithm to schedule and process active packets, and import an interval queue method to allocate transmission bandwidth, and use feedback mechanism to control congestion. At the same time, we design some experiments on prototype systems with and without resources management policies respectively. The experiments results show that management policies presented by us can effectively manage resources in active nodes and can improve the performance of active networks.
AQM Algorithm with Adaptive Reference Queue Threshold for Communication Networks
Liming Chen
2012-09-01
Full Text Available Nowadays, congestion in communication networks has been more intractable than ever before due to the explosive growth of network scale and multimedia traffic. Active queue management (AQM algorithms had been proposed to alleviate congestion to improve quality of service (QoS, but existing algorithms often suffer from some flaws in one aspect or another. In this paper, a novel AQM algorithm with adaptive reference queue threshold (ARTAQM is proposed of which the main innovative contributions are recounted as follows. First, traffic is predicted to calculate the packet loss ratio (PLR and the traffic rate based on traffic prediction algorithm. Second, by means of periodical measurements, a weighted PLR is obtained to dynamically adjust packet dropping probability in ARTAQM algorithm. Third, ARTAQM algorithm runs in both coarse and fine granularities. In coarse granularity, the mismatch of the predicted traffic rate and link capacity can adjusts the reference queue length in every period, while in fine granularity, reference queue remains fixed and the instantaneous queue is adjusted packet by packet in one period. Simulation results indicate that ARTAQM algorithm not only maintains stable queue and fast response speed, but has lower PLR and higher link utilization as well.
Vacation queueing models theory and applications
Tian, Naishuo
2006-01-01
A classical queueing model consists of three parts - arrival process, service process, and queue discipline. However, a vacation queueing model has an additional part - the vacation process which is governed by a vacation policy - that can be characterized by three aspects: 1) vacation start-up rule; 2) vacation termination rule, and 3) vacation duration distribution. Hence, vacation queueing models are an extension of classical queueing theory. Vacation Queueing Models: Theory and Applications discusses systematically and in detail the many variations of vacation policy. By allowing servers to take vacations makes the queueing models more realistic and flexible in studying real-world waiting line systems. Integrated in the book's discussion are a variety of typical vacation model applications that include call centers with multi-task employees, customized manufacturing, telecommunication networks, maintenance activities, etc. Finally, contents are presented in a "theorem and proof" format and it is invaluabl...
Adaptive Filtering Queueing for Improving Fairness
Jui-Pin Yang
2015-06-01
Full Text Available In this paper, we propose a scalable and efficient Active Queue Management (AQM scheme to provide fair bandwidth sharing when traffic is congested dubbed Adaptive Filtering Queueing (AFQ. First, AFQ identifies the filtering level of an arriving packet by comparing it with a flow label selected at random from the first level to an estimated level in the filtering level table. Based on the accepted traffic estimation and the previous fair filtering level, AFQ updates the fair filtering level. Next, AFQ uses a simple packet-dropping algorithm to determine whether arriving packets are accepted or discarded. To enhance AFQ’s feasibility in high-speed networks, we propose a two-layer mapping mechanism to effectively simplify the packet comparison operations. Simulation results demonstrate that AFQ achieves optimal fairness when compared with Rotating Preference Queues (RPQ, Core-Stateless Fair Queueing (CSFQ, CHOose and Keep for responsive flows, CHOose and Kill for unresponsive flows (CHOKe and First-In First-Out (FIFO schemes under a variety of traffic conditions.
Preventing messaging queue deadlocks in a DMA environment
Blocksome, Michael A; Chen, Dong; Gooding, Thomas; Heidelberger, Philip; Parker, Jeff
2014-01-14
Embodiments of the invention may be used to manage message queues in a parallel computing environment to prevent message queue deadlock. A direct memory access controller of a compute node may determine when a messaging queue is full. In response, the DMA may generate and interrupt. An interrupt handler may stop the DMA and swap all descriptors from the full messaging queue into a larger queue (or enlarge the original queue). The interrupt handler then restarts the DMA. Alternatively, the interrupt handler stops the DMA, allocates a memory block to hold queue data, and then moves descriptors from the full messaging queue into the allocated memory block. The interrupt handler then restarts the DMA. During a normal messaging advance cycle, a messaging manager attempts to inject the descriptors in the memory block into other messaging queues until the descriptors have all been processed.
Handover Management for VoWLAN Based on Estimation of AP Queue Length and Frame Retries
Niswar, Muhammad; Kashihara, Shigeru; Tsukamoto, Kazuya; Kadobayashi, Youki; Yamaguchi, Suguru
Switching a communication path from one Access Point (AP) to another in inter-domain WLANs is a critical challenge for delay-sensitive applications such as Voice over IP (VoIP) because communication quality during handover (HO) is more likely to be deteriorated. To maintain VoIP quality during HO, we need to solve many problems. In particular, in bi-directional communication such as VoIP, an AP becomes a bottleneck with the increase of VoIP calls. As a result, packets queued in the AP buffer may experience a large queuing delay or packet losses due to increase in queue length or buffer overflow, thereby causing the degradation of VoIP quality for the Mobile Nodes (MNs) side. To avoid this degradation, MNs need to appropriately and autonomously execute HO in response to the change in wireless network condition, i.e., the deterioration of wireless link quality and the congestion state at the AP. In this paper, we propose an HO decision strategy considering frame retries, AP queue length, and transmission rate at an MN for maintaining VoIP quality during HO. Through simulation experiments, we then show that our proposed method can maintain VoIP quality during HO by properly detecting the wireless network condition.
Probability, statistics, and queueing theory
Allen, Arnold O
1990-01-01
This is a textbook on applied probability and statistics with computer science applications for students at the upper undergraduate level. It may also be used as a self study book for the practicing computer science professional. The successful first edition of this book proved extremely useful to students who need to use probability, statistics and queueing theory to solve problems in other fields, such as engineering, physics, operations research, and management science. The book has also been successfully used for courses in queueing theory for operations research students. This second edit
Jain, Joti Lal; Böhm, Walter
2006-01-01
The application of engineering principles in divergent fields such as management science and communications as well as the advancement of several approaches in theory and computation have led to growing interest in queueing models, creating the need for a comprehensive text. Emphasizing Markovian structures and the techniques that occur in different models, A Course on Queueing Models discusses recent developments in the field, different methodological tools - some of which are not available elsewhere - and computational techniques.While most books essentially address the classical methods of
Mathematical Analysis of Queue with Phase Service: An Overview
Richa Sharma
2014-01-01
Full Text Available We discuss various aspects of phase service queueing models. A large number of models have been developed in the area of queueing theory incorporating the concept of phase service. These phase service queueing models have been investigated for resolving the congestion problems of many day-to-day as well as industrial scenarios. In this survey paper, an attempt has been made to review the work done by the prominent researchers on the phase service queues and their applications in several realistic queueing situations. The methodology used by several researchers for solving various phase service queueing models has also been described. We have classified the related literature based on modeling and methodological concepts. The main objective of present paper is to provide relevant information to the system analysts, managers, and industry people who are interested in using queueing theory to model congestion problems wherein the phase type services are prevalent.
An Optimal Lower Bound for Buffer Management in Multi-Queue Switches
Bienkowski, Marcin
2010-01-01
In the online packet buffering problem (also known as the unweighted FIFO variant of buffer management), we focus on a single network packet switching device with several input ports and one output port. This device forwards unit-size, unit-value packets from input ports to the output port. Buffers attached to input ports may accumulate incoming packets for later transmission; if they cannot accommodate all incoming packets, their excess is lost. A packet buffering algorithm has to choose fro...
Increasing available FIFO space to prevent messaging queue deadlocks in a DMA environment
Blocksome, Michael A.; Chen, Dong; Gooding, Thomas; Heidelberger, Philip; Parker, Jeff
2012-02-07
Embodiments of the invention may be used to manage message queues in a parallel computing environment to prevent message queue deadlock. A direct memory access controller of a compute node may determine when a messaging queue is full. In response, the DMA may generate an interrupt. An interrupt handler may stop the DMA and swap all descriptors from the full messaging queue into a larger queue (or enlarge the original queue). The interrupt handler then restarts the DMA. Alternatively, the interrupt handler stops the DMA, allocates a memory block to hold queue data, and then moves descriptors from the full messaging queue into the allocated memory block. The interrupt handler then restarts the DMA. During a normal messaging advance cycle, a messaging manager attempts to inject the descriptors in the memory block into other messaging queues until the descriptors have all been processed.
Heidelberger, Philip; Steinmacher-Burow, Burkhard
2015-01-06
According to one embodiment, a method for implementing an array-based queue in memory of a memory system that includes a controller includes configuring, in the memory, metadata of the array-based queue. The configuring comprises defining, in metadata, an array start location in the memory for the array-based queue, defining, in the metadata, an array size for the array-based queue, defining, in the metadata, a queue top for the array-based queue and defining, in the metadata, a queue bottom for the array-based queue. The method also includes the controller serving a request for an operation on the queue, the request providing the location in the memory of the metadata of the queue.
Brodal, Gerth Stølting
1995-01-01
We present priority queues that support the operations Find-Min, Insert, MakeQueue and Meld in worst case time O(1) and Delete and DeleteMin in worst case time O(log n). They can be implemented on the pointer machine and require linear space. The time bounds are optimal for all implementations wh...... where Meld takes worst case time o(n). To our knowledge this is the first priority queue implementation that supports Meld in worst case constant time and DeleteMin in logarithmic time....
Fundamentals of queueing theory
Gross, Donald; Thompson, James M; Harris, Carl M
2013-01-01
Praise for the Third Edition ""This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented.""-IIE Transactions on Operations Engineering Thoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than pre
The queue-length in GI/G/s queues
Pierre Le Gall
2000-01-01
Full Text Available The distribution of the queue-length in the stationary symmetrical GI/G/s queue is given with an application to the M/G/s queue, particularly in the case of the combination of several packet traffics, with various constant service times, to dimension the buffer capacity.
Single server queueing networks with varying service times and renewal input
Pierre Le Gall
2000-01-01
Full Text Available Using recent results in tandem queues and queueing networks with renewal input, when successive service times of the same customer are varying (and when the busy periods are frequently not broken up in large networks, the local queueing delay of a single server queueing network is evaluated utilizing new concepts of virtual and actual delays (respectively. It appears that because of an important property, due to the underlying tandem queue effect, the usual queueing standards (related to long queues cannot protect against significant overloads in the buffers due to some possible agglutination phenomenon (related to short queues. Usual network management methods and traffic simulation methods should be revised, and should monitor the partial traffic streams loads (and not only the server load.
Robust Scheduling for Queueing Networks
Pedarsani, Ramtin
2015-01-01
Queueing networks are used to model complicated processing environments such as data centers, call centers, transportation networks, health systems, etc. A queueing network consists of multiple interconnected queues with some routing structure, and a set of servers that have different and possibly overlapping capabilities in processing tasks (jobs) of different queues. One of the most important challenges in designing processing systems is to come up with a low-complexity and efficient schedu...
Draief, Moez; O'Connell, Neil
2005-01-01
Consider the single server queue with an infinite buffer and a FIFO discipline, either of type M/M/1 or Geom/Geom/1. Denote by A the arrival process and by s the services. Assume the stability condition to be satisfied. Denote by D the departure process in equilibrium and by r the time spent by the customers at the very back of the queue. We prove that (D,r) has the same law as (A,s) which is an extension of the classical Burke Theorem. In fact, r can be viewed as the departures from a dual storage model. This duality between the two models also appears when studying the transient behavior of a tandem by means of the RSK algorithm: the first and last row of the resulting semi-standard Young tableau are respectively the last instant of departure in the queue and the total number of departures in the store.
We introduce the prioritising exclusion process, a stochastic scheduling mechanism for a priority queueing system in which high priority customers gain advantage by overtaking low priority customers. The model is analogous to a totally asymmetric exclusion process with a dynamically varying lattice length. We calculate exact local density profiles for an unbounded queue by deriving domain wall dynamics from the microscopic transition rules. The structure of the unbounded queue carries over to bounded queues where, although no longer exact, we find the domain wall theory is in very good agreement with simulation results. Within this approximation we calculate average waiting times for queueing customers. (paper)
Queueing system with passive servers
Alexander N. Dudin
1996-01-01
Full Text Available In this paper the authors introduce systems in which customers are served by one active server and a group of passive servers. The calculation of response time for such systems is rendered by analyzing a special kind of queueing system in a synchronized random environment. For an embedded Markov chain, sufficient conditions for the existence of a stationary distribution are proved. A formula for the corresponding vector generating function is obtained. It is a matrix analog of the Pollaczek-Khinchin formula and is simultaneously a matrix functional equation. A method for solving this equation is proposed.
Multiserver queueing networks and the tandem queue model
Pierre Le Gall
1998-01-01
Full Text Available Using a tandem queue model we evaluate the local endogenous (= internal queueing delay in single server and multiserver queueing networks. The new concept of the apparent overall upstream queueing delay(as perceived by the downstream network allows us to analyze the distribution of this local queue by interpolating between the distributions of the tandem queue (generated by a concentration tree and the isolated G/G/squeue. The interpolation coefficients depend on the proportion of premature departures, typically interfering in the upstream stage and leaving the considered path without being offered to the considered local queue. On the other hand, local exogenous arrivals (from outside the network require the introduction of the interference delay concept. Finally, in the case of single server queueing networks, we stress the need to extend the capacities of the buffers, by considering the worst case scenario and by using an equivalent tandem queue model.
Updatable Queue Protocol Based On TCP For Virtual Reality Environment
Al-Howaide, Ala'a Z; Salhieh, Ayad M
2011-01-01
The variance in number and types of tasks required to be implemented within Distributed Virtual Environments (DVE) highlights the needs for communication protocols can achieve consistency. In addition, these applications have to handle an increasing number of participants and deal with the difficult problem of scalability. Moreover, the real-time requirements of these applications make the scalability problem more difficult to solve. In this paper, we have implemented Updatable Queue Abstraction protocol (UQA) on TCP (TCP-UQA) and compared it with original TCP, UDP, and Updatable Queue Abstraction based on UDP (UDP-UQA) protocols. Results showed that TCP-UQA was the best in queue management.
Analysis and Optimization of a Multistage Inventory-Queue System
Liming Liu; Xiaoming Liu; David D. Yao
2004-01-01
An important issue in the management of supply chains and manufacturing systems is to control inventory costs at different locations throughout the system while satisfying an end-customer service-level requirement. The challenge involved is to solve a nonlinear constrained optimization problem that captures the key dynamics of a complex production-inventory system. In this paper, we first develop a multistage inventory-queue model and a job-queue decomposition approach that evaluates the perf...
Optimal purely functional priority queues
Brodal, Gerth Stølting; Okasaki, Chris
1996-01-01
Brodal's data structure to a purely functional setting. In doing so, we both simplify the data structure and clarify its relationship to the binomial queues of Vuillemin, which support all four operations in O(log n) time. Specifically, we derive our implementation from binomial queues in three steps...
Brodal, Gerth Stølting
2013-01-01
Back in 1964 Williams introduced the binary heap as a basic priority queue data structure supporting the operations Insert and ExtractMin in logarithmic time. Since then numerous papers have been published on priority queues. This paper tries to list some of the directions research on priority...
On The Inequality In Open Queueing Networks
Minkevicius, S.
2011-01-01
The paper is devoted to the analysis of queueing systems in the context of the network and communications theory. We investigate the inequality in an open queueing network and its applications to the theorems in heavy traffic conditions (fluid approx-imation, functional limit theorem, and law of the iterated logarithm) for a queue of customers in an open queueing network.
Two-Queue Polling Model with a Timer and a Randomly-Timed Gated Mechanism
LI Jin Zhi
2009-01-01
In this paper, we consider two-queue polling model with a Timer and a RandomlyTimed Gated (RTG) mechanism. At queue Q1, we employ a Timer T(1): whenever the server polls queue Q1 and finds it empty, it activates a Timer. If a customer arrives before the Timer expires, a busy period starts in accordance with exhaustive service discipline. However, if the Timer is shorter than the interarrival time to queue Q1, the server does not wait any more and switches back to queue Q2. At queue Q2, we operate a RTG mechanism T(2), that is, whenever the server reenters queue Q2, an exponential time T(2) is activated. If the server empties the queue before T(2), it immediately leaves for queue Q1. Otherwise, the server completes all the work accumulated up to time T(2) and leaves. Under the assumption of Poisson arrivals, general service and switchover time distributions, we obtain probability generating function (PGF) of the queue lengths at polling instant and mean cycle length and Laplace Stieltjes transform (LST) of the workload.
Alfa, Attahiru S
2016-01-01
This book introduces the theoretical fundamentals for modeling queues in discrete-time, and the basic procedures for developing queuing models in discrete-time. There is a focus on applications in modern telecommunication systems. It presents how most queueing models in discrete-time can be set up as discrete-time Markov chains. Techniques such as matrix-analytic methods (MAM) that can used to analyze the resulting Markov chains are included. This book covers single node systems, tandem system and queueing networks. It shows how queues with time-varying parameters can be analyzed, and illustrates numerical issues associated with computations for the discrete-time queueing systems. Optimal control of queues is also covered. Applied Discrete-Time Queues targets researchers, advanced-level students and analysts in the field of telecommunication networks. It is suitable as a reference book and can also be used as a secondary text book in computer engineering and computer science. Examples and exercises are includ...
Queueing theory and network applications
Takahashi, Yutaka; Yue, Wuyi; Nguyen, Viet-Ha
2016-01-01
The 16 papers of this proceedings have been selected from the submissions to the 10th International Conference on Queueing Theory and Network Applications (QTNA2015) held on 17-20 August, 2015 in Ha Noi and Ha Long, Vietnam. All contributions discuss theoretical and practical issues connected with queueing theory and its applications in networks and other related fields. The book brings together researchers, scientists and practitioners from the world and offers an open forum to share the latest important research accomplishments and challenging problems in the area of queueing theory and network applications.
Jaschob Daniel
2012-07-01
Full Text Available Abstract Background Laboratories engaged in computational biology or bioinformatics frequently need to run lengthy, multistep, and user-driven computational jobs. Each job can tie up a computer for a few minutes to several days, and many laboratories lack the expertise or resources to build and maintain a dedicated computer cluster. Results JobCenter is a client–server application and framework for job management and distributed job execution. The client and server components are both written in Java and are cross-platform and relatively easy to install. All communication with the server is client-driven, which allows worker nodes to run anywhere (even behind external firewalls or “in the cloud” and provides inherent load balancing. Adding a worker node to the worker pool is as simple as dropping the JobCenter client files onto any computer and performing basic configuration, which provides tremendous ease-of-use, flexibility, and limitless horizontal scalability. Each worker installation may be independently configured, including the types of jobs it is able to run. Executed jobs may be written in any language and may include multistep workflows. Conclusions JobCenter is a versatile and scalable distributed job management system that allows laboratories to very efficiently distribute all computational work among available resources. JobCenter is freely available at http://code.google.com/p/jobcenter/.
Optimal control of two queues in series
In this paper we give a fairly complete survey of the available results on the control of arrival and service rates for both single queue and networks of queues. We also study two M/M/1 queues in series. At the first queue, the arrival and the service rates are chosen in pair from a finite set whenever the queue lengths at both queues change. Each choice has a switching cost depending on the chosen rates and the queue lengths. At the second queue, the arrival and the service rates are fixed. Our objective is to find a policy for dynamically choosing rates, based on the current rates and queues lengths that minimizes the expected total discounted cost over a finite horizon, numerical results are given. (author). 8 refs, 1 fig
Queueing networks a fundamental approach
Dijk, Nico
2011-01-01
This handbook aims to highlight fundamental, methodological and computational aspects of networks of queues to provide insights and to unify results that can be applied in a more general manner. The handbook is organized into five parts: Part 1 considers exact analytical results such as of product form type. Topics include characterization of product forms by physical balance concepts and simple traffic flow equations, classes of service and queue disciplines that allow a product form, a unified description of product forms for discrete time queueing networks, insights for insensitivity, and aggregation and decomposition results that allow subnetworks to be aggregated into single nodes to reduce computational burden. Part 2 looks at monotonicity and comparison results such as for computational simplification by either of two approaches: stochastic monotonicity and ordering results based on the ordering of the proces generators, and comparison results and explicit error bounds based on an underlying Markov r...
Boxma, O.J.
1984-01-01
We consider a series of queues with Poisson input. Each queueing system contains an infinite number of service channels. The service times in each channel have a general distribution. For this M/G∞ tandem model we obtain the joint time-dependent distribution of queue length and residual service tim
Random queues and risk averse users
de Palma, André; Fosgerau, Mogens
2013-01-01
We analyze Nash equilibrium in time of use of a congested facility. Users are risk averse with general concave utility. Queues are subject to varying degrees of random sorting, ranging from strict queue priority to a completely random queue. We define the key “no residual queue” property, which...
Delay in a tandem queueing model with mobile queues : an analytical approximation
Al Hanbali, A Ahmad; Haan; Boucherie, RJ Richard; Ommeren, van, J.C.
2009-01-01
In this paper, we analyze the end-to-end delay performance of a tandem queueing system with mobile queues. Due to state-space explosion there is no hope for a numerical exact analysis for the joint-queue length distribution. For this reason, we present an analytical approximation that is based on queue length analysis. Through extensive numerical validation, we nd that the queue length approximation exhibits excellent performance for light tra c load.
Amita CHOUDHARY
2011-01-01
Full Text Available While in multi-user environment, CPU has to manage lot of requests generated over the same time. Waiting queue of processes generates a problem of scheduling for processors. Designers and hardware architects have suggested system of multiprocessors to overcome the queue length. Lottery scheduling is one such method where processes in waiting queue are selected through a chance manner. This opens a way to use probability models to get estimates of system parameters. This paper is an application where the processing time of jobs in ready queue is predicted using the sampling method under the k-processors environment (k>1.The random selection of one process by each of k processors through without replacement method is a sample data set which helps in the prediction of possible ready queue processing time. Some theorems are established and proved to get desired results in terms of confidence intervals.
王霞; 姜宏岸
2014-01-01
为了解决由于网络环境中多媒体业务需求的快速增加，导致应用对延迟和拥塞概率等性能指标的要求逐渐提高的问题，提出了一种改进的优先级队列的缓存管理机制。详细研究了该机制的实现原理和方法，并使用Petri工具及排队理论对改进的优先级队列进行了建模。通过仿真实验分析了该缓存管理机制在缓存管理过程中的性能指标，证明了该缓存管理机制能有效地提高多媒体通信的性能，满足多媒体通信的服务质量要求。%The rapid increase of multimedia services in the network environment has led to higher requirements for the handling of network latency and high-rate packet loss.We proposed an im-proved priority queue based buffer management mechanism in this paper to cope with this prob-lem.We probed in detail into the principle and implementation method of the mechanism,and es-tablished a model on the improved priority queue by using the Petri net tools and queuing theory. Through simulation analysis,we analyzed the buffer management mechanism performance index in the process of buffer management,proving that the mechanism can effectively improve the per-formance of communication,and meet the requirements of multimedia communication service.
QUEUEING NETWORKS WITH INSTANTANEOUSSEQUENTIAL TRANSITIONS
Chao Xiuli
2001-01-01
We study queueing networks with instantaneous transitions of sequential batch departures and sequential batch arrivals. Unlike most of the existing models, this network is shown not to have a product form solution. An "extra arrival condition” is introduced under which the network is shown to possess a product form stationary distribution. Furthermore, the product form solution serves as a stochastic upper bound for the original network without the extra arrival process. The results include many queueing network models reported in the literature, e.g. the assembly transfer networks recently introduced by Miyazawa and Taylor, as special cases. We show that the network with the extra arrival process is "structurally reversible” in the sense that its reversed process has the same network structure. Local balances for this network are presented and discussed.
Analysis of queues methods and applications
Gautam, Natarajan
2012-01-01
Introduction Analysis of Queues: Where, What, and How?Systems Analysis: Key ResultsQueueing Fundamentals and Notations Psychology in Queueing Reference Notes Exercises Exponential Interarrival and Service Times: Closed-Form Expressions Solving Balance Equations via Arc CutsSolving Balance Equations Using Generating Functions Solving Balance Equations Using Reversibility Reference Notes ExercisesExponential Interarrival and Service Times: Numerical Techniques and Approximations Multidimensional Birth and Death ChainsMultidimensional Markov Chains Finite-State Markov ChainsReference Notes Exerci
Eckhardt, D. E., Jr.
1979-01-01
A model of a central processor (CPU) which services background applications in the presence of time critical activity is presented. The CPU is viewed as an M/M/1 queueing system subject to periodic interrupts by deterministic, time critical process. The Laplace transform of the distribution of service times for the background applications is developed. The use of state of the art queueing models for studying the background processing capability of time critical computer systems is discussed and the results of a model validation study which support this application of queueing models are presented.
Bayes Estimation of Queue Length
Dohnal, Pavel
Praha : ÚTIA AV ČR, 2006 - (Přikryl, J.; Šmídl, V.). s. 47-48 [International PhD Workshop on Interplay of Societal and Technical Decision-Making, Young Generation Viewpoint /7./. 25.09.2006-30.09.2006, Hrubá Skála] R&D Projects: GA AV ČR 1ET100750401; GA MŠk 1M0572 Institutional research plan: CEZ:AV0Z10750506 Keywords : traffic flow * queue length * occupancy * intensity Subject RIV: BC - Control Systems Theory
Bayes Estimation of Queue Length
Dohnal, Pavel
Praha : ÚTIA AV ČR, 2006 - ( And rýsek, J.), s. 1-8 [International PhD Workshop on Interplay of Societal and Technical Decision-Making, Young Generation Viewpoint /7./. Hrubá Skála (CZ), 25.09.2006-30.09.2006] R&D Projects: GA MŠk 1M0572; GA AV ČR 1ET100750401 Institutional research plan: CEZ:AV0Z10750506 Keywords : Bayes estimation * queue length * traffic flow * occupancy * intensity Subject RIV: BC - Control Systems Theory
Priority-queue framework: Programs
Katajainen, Jyrki
2009-01-01
This is an electronic appendix to the article "Generic-programming framework for benchmarking weak queues and its relatives". The report contains the programs related to our priority-queue framework. Look at the CPH STL reports 2009-3 and 2009-4 to see examples of other component frameworks....
Queue Layouts of Graph Products and Powers
David R. Wood
2005-12-01
Full Text Available A k-queue layout of a graph G consists of a linear order σ of V(G, and a partition of E(G into k sets, each of which contains no two edges that are nested in σ. This paper studies queue layouts of graph products and powers
Priority Queues Resilient to Memory Faults
Jørgensen, Allan Grønlund; Moruz, Gabriel; Mølhave, Thomas
2007-01-01
In the faulty-memory RAM model, the content of memory cells can get corrupted at any time during the execution of an algorithm, and a constant number of uncorruptible registers are available. A resilient data structure in this model works correctly on the set of uncorrupted values. In this paper we...... introduce a resilient priority queue. The deletemin operation of a resilient priority queue returns either the minimum uncorrupted element or some corrupted element. Our resilient priority queue uses $O(n)$ space to store $n$ elements. Both insert and deletemin operations are performed in $O(\\log n......+\\delta)$ time amortized, where $\\delta$ is the maximum amount of corruptions tolerated. Our priority queue matches the performance of classical optimal priority queues in the RAM model when the number of corruptions tolerated is $O(\\log n)$. We prove matching worst case lower bounds for resilient priority...
MultiQueues: Simpler, Faster, and Better Relaxed Concurrent Priority Queues
Rihani, Hamza; Sanders, Peter; Dementiev, Roman
2014-01-01
Priority queues with parallel access are an attractive data structure for applications like prioritized online scheduling, discrete event simulation, or branch-and-bound. However, a classical priority queue constitutes a severe bottleneck in this context, leading to very small throughput. Hence, there has been significant interest in concurrent priority queues with a somewhat relaxed semantics where deleted elements only need to be close to the minimum. In this paper we present a very simple ...
The theory of networks of single server queues and the tandem queue model
Pierre Le Gall
1997-01-01
Full Text Available We consider the stochastic behavior of networks of single server queues when successive service times of a given customer are highly correlated. The study is conducted in two particular cases: 1 networks in heavy traffic, and 2 networks in which all successive service times have the same value (for a given customer, in order to avoid the possibility of breaking up the busy periods. We then show how the local queueing delay (for an arbitrary customer can be derived through an equivalent tandem queue on the condition that one other local queueing delay is added: the jitter delay due to the independence of partial traffic streams.
Queues and Lévy fluctuation theory
Dębicki, Krzysztof
2015-01-01
The book provides an extensive introduction to queueing models driven by Lévy-processes as well as a systematic account of the literature on Lévy-driven queues. The objective is to make the reader familiar with the wide set of probabilistic techniques that have been developed over the past decades, including transform-based techniques, martingales, rate-conservation arguments, change-of-measure, importance sampling, and large deviations. On the application side, it demonstrates how Lévy traffic models arise when modelling current queueing-type systems (as communication networks) and includes applications to finance. Queues and Lévy Fluctuation Theory will appeal to graduate/postgraduate students and researchers in mathematics, computer science, and electrical engineering. Basic prerequisites are probability theory and stochastic processes.
QUALIFYING PURCHASE INTENTIONS USING QUEUEING THEORY
Ercan TIRTIROGLU
2008-06-01
Full Text Available We propose that a consumer’s purchase behaviour emulates a cognitive framework such that an appropriately selected queueing model can be used to assess the credibility of a consumer’s expression of purchase intention to proceed into purchase action. The modelling idea is to envision that the customer has a mental queue of needs, and the surfacing of a need represents a new arrival to this queue while a purchase satisfying a need represents a departure from the queue. Using queueing formulae (and/or readily available tables on queueing, several statistics known as "operating characteristics" can be computed to capture and describe the individual’s current need status. Hence, a description of the customer’s state of readiness or prospect of actually executing the expressed purchase intention for a product (good or service whose future sales are of interest in a market survey may be obtained. In this paper, such a description is termed Individual Buyer Profile (IBP, and IBP is offered as a purchase intention qualifier.
Fixed points for multi-class queues
Martin, James B
2010-01-01
Burke's theorem can be seen as a fixed-point result for an exponential single-server queue; when the arrival process is Poisson, the departure process has the same distribution as the arrival process. We consider extensions of this result to multi-type queues, in which different types of customer have different levels of priority. We work with a model of a queueing server which includes discrete-time and continuous-time M/M/1 queues as well as queues with exponential or geometric service batches occurring in discrete time or at points of a Poisson process. The fixed-point results are proved using interchangeability properties for queues in tandem, which have previously been established for one-type M/M/1 systems. Some of the fixed-point results have previously been derived as a consequence of the construction of stationary distributions for multi-type interacting particle systems, and we explain the links between the two frameworks. The fixed points have interesting "clustering" properties for lower-priority ...
Chen, Gang; Govindan, Kannan; Yang, Zhong-Zhen;
2013-01-01
Long truck queue is a common problem at big marine container terminals, where the resources and equipment are usually scheduled to serve ships prior to trucks. To reduce truck queues, some container terminals adopt terminal appointment system (TAS) to manage truck arrivals. This paper addresses two...
Bridging genetic networks and queueing theory
Arazi, Arnon; Ben-Jacob, Eshel; Yechiali, Uri
2004-02-01
One of the main challenges facing biology today is the understanding of the joint action of genes, proteins and RNA molecules, interwoven in intricate interdependencies commonly known as genetic networks. To this end, several mathematical approaches have been introduced to date. In addition to developing the analytical tools required for this task anew, one can utilize knowledge found in existing disciplines, specializing in the representation and analysis of systems featuring similar aspects. We suggest queueing theory as a possible source of such knowledge. This discipline, which focuses on the study of workloads forming in a variety of scenarios, offers an assortment of tools allowing for the derivation of the statistical properties of the inspected systems. We argue that a proper adaptation of modeling techniques and analytical methods used in queueing theory can contribute to the study of genetic regulatory networks. This is demonstrated by presenting a queueing-inspired model of a genetic network of arbitrary size and structure, for which the probability distribution function is derived. This model is further applied to the description of the lac operon regulation mechanism. In addition, we discuss the possible benefits stemming for queueing theory from the interdisciplinary dialogue with molecular biology-in particular, the incorporation of various dynamical behaviours into queueing networks.
One of the missions of the Department of Energy's (DOE) Oak Ridge Office (ORO) has been the management of the Department's uranium materials. This mission has been accomplished through successful integration of ORO's uranium activities with the rest of the DOE complex. Beginning in the 1980's, several of the facilities in that complex have been shut down and are in the decommissioning process. With the end of the Cold War, the shutdown of many other facilities is planned. As a result, inventories of uranium need to be removed from the Department facilities. These inventories include highly enriched uranium (HEU), low enriched uranium (LEU), normal uranium (NU), and depleted uranium (DU). The uranium materials exist in different chemical forms, including metals, oxides, solutions, and gases. Much of the uranium in these inventories is not needed to support national priorities and programs. (author)
餐饮服务排队管理中等候区设置必要性研究%Research on the Necessity of Setting Waiting Room in Restaurant Queue Management
韩亚娟; 谢会
2012-01-01
To improve restaurant service quality and increase revenue, the issue of restaurant queue man-agement is discussed in an integrated perspective of both capacity management and the psychology of wait-ing in line. Two cases are considered: 1) there is no waiting room, leading to loss of customers; and 2) there is a waiting room, but some customers may renege because of the waiting time. With customer per-ception in waiting considered, queuing theory models are developed for both cases. To maximize profit, revenue functions for the models are derived. Then, simulation analysis is done by using Matlab. It shows that there is a strategy of setting waiting room such that maximum profit can be achieved, which indicates that the traditional view of conflict between service quality and cost can be overcome by integrating per-spective from both customers and the company. In addition, the number of dinner tables is negatively re-lated to the reneging parameter, whereas the number of waiting tables is positively related to the reneging parameter.%为了达到同时提高饭店服务质量和收益的双重目的,从顾客等待心理和饭店能力管理相结合的角度研究了饭店排队管理问题,提出了建立顾客等候区的排队管理策略.充分考虑顾客感知等待时间,采用排队论的方法分别建立了在不设置等候区时的损失制排队模型及设置等候区时的带有顾客中途退出的排队模型,并以饭店收益最大化为目标建立两种模型下的收益函数,最后用Matlab编程比较分析了两个模型.结果表明:设置等侯区能够使饭店获得更大的收益；同时,要保证利润最大,餐桌数与顾客中途退出指数成负相关,等候桌数与顾客中途退出指数成正相关,这为进行有效排队管理提供了理论依据.
Difference and differential equations with applications in queueing theory
Haghighi, Aliakbar Montazer
2013-01-01
A Useful Guide to the Interrelated Areas of Differential Equations, Difference Equations, and Queueing Models Difference and Differential Equations with Applications in Queueing Theory presents the unique connections between the methods and applications of differential equations, difference equations, and Markovian queues. Featuring a comprehensive collection of
Threshold queueing describes the fundamental diagram of uninterrupted traffic
Baer, Niek; Boucherie, Richard J.; Ommeren, van, J.C.
2012-01-01
Queueing due to congestion is an important aspect of road traffic. This paper provides a brief overview of queueing models for traffic and a novel threshold queue that captures the main aspects of the empirical shape of the fundamental diagram. Our numerical results characterises the sources of variation that influence the shape of the fundamental diagram.
A Queue Simulation Tool for a High Performance Scientific Computing Center
Spear, Carrie; McGalliard, James
2007-01-01
The NASA Center for Computational Sciences (NCCS) at the Goddard Space Flight Center provides high performance highly parallel processors, mass storage, and supporting infrastructure to a community of computational Earth and space scientists. Long running (days) and highly parallel (hundreds of CPUs) jobs are common in the workload. NCCS management structures batch queues and allocates resources to optimize system use and prioritize workloads. NCCS technical staff use a locally developed discrete event simulation tool to model the impacts of evolving workloads, potential system upgrades, alternative queue structures and resource allocation policies.
Algorithms for Scheduling Weighted Packets with Deadlines in a Bounded Queue
LI Fei
2008-01-01
Motivated by the Quality-of-Service (QoS) buffer management problem, we consider online scheduling of packets with hard deadlines in a finite capacity queue. At any time, a queue can store at most $b \\in \\mathbb Z^+$ packets. Packets arrive over time. Each packet is associated with a non-negative value and an integer deadline. In each time step, only one packet is allowed to be sent. Our objective is to maximize the total value gained by the packets sent by their deadlines in an online manner...
Stochastic Processes and Queueing Theory used in Cloud Computer Performance Simulations
Florin-Catalin ENACHE
2015-10-01
Full Text Available The growing character of the cloud business has manifested exponentially in the last 5 years. The capacity managers need to concentrate on a practical way to simulate the random demands a cloud infrastructure could face, even if there are not too many mathematical tools to simulate such demands.This paper presents an introduction into the most important stochastic processes and queueing theory concepts used for modeling computer performance. Moreover, it shows the cases where such concepts are applicable and when not, using clear programming examples on how to simulate a queue, and how to use and validate a simulation, when there are no mathematical concepts to back it up.
A Service Ratio-Based Dynamic Fair Queueing Algorithm for Packet Switching Networks
YIN De-bin; XIE Jian-ying; ZHANG Yan; WU Jian-zhen; SUN Hua-li
2008-01-01
A new weighted fair queeetng algodthm is proposed,which uses the novel flow-based service ratio parameters to schedule flows.This solves the main drawback of traditional weighted fair quoneing algorithmsthe packet-based calculation of the weight parameters.In addition,this paper proposes a novel service ratio calculation method and a queue management techaology.The former adjusts the service ratio parameters adaptively based on the dynamics of the packet lengths and then solves the unfairness problem induced by the variable packet length.The latter impgoves the utilization of the server's queue buffeg and reduces the delay jitter throegh restricting the buffer length for each flow.
Peter Wanke
2011-04-01
Full Text Available The ship-berth link is one of the most critical aspects to be managed at port operations. Until now, simulation models have considered the impact of queue priorities, such as size and type of ships, on waiting times. This research differentiates from previous studies not only by considering another variable - the demurrage cost for each type of ship -, but also by considering the possibility of different berth allocation policies. It reports on a simulation study on small Brazilian private container terminal, where different berth allocation policies and queue priorities have been tested. Results and further analyses conducted via MANOVA indicate that the demurrage cost ratio between large and small ships and the critical waiting time in queue, after which demurrage costs are charged, impact on the choice of most adequate combination of policies and priorities. The analysis presented in this paper may help port authorities in determining a more precise figure for total demurrage costs
Task Release Control for Decision Making Queues
Srivastava, Vaibhav; Bullo, Francesco; Langbort, Cédric
2010-01-01
We consider the optimal duration allocation in a decision making queue. Decision making tasks arrive at a given rate to a human operator. The correctness of the decision made by human evolves as a sigmoidal function of the duration allocated to the task. Each task in the queue loses its value continuously. We elucidate on this trade-off and determine optimal policies for the human operator. We show the optimal policy requires the human to drop some tasks. We present a receding horizon optimization strategy, and compare it with the greedy policy.
TRANSIENT SOLUTION FOR QUEUE-LENGTH DISTRIBUTION OF Geometry/G/1 QUEUEING MODEL
Luo Chuanyi; Tang Yinghui; Liu Renbin
2007-01-01
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.
Call packing bounds for overflow queues
N.M. van Dijk; E. van der Sluis
2004-01-01
Finite queueing loss systems are studied with overflow. For these systems there is no simple analytic expression for the loss probability or throughput. This paper aims to prove and promote easily computable bounds as based upon the so-called call packing principle. Under call packing a standard pro
Optimal control of arrival and service rates in tandem queues
We consider n M/M/1 queues in series. At queue one the arrival and service rates are chosen in pair from a finite set whenever there are arrivals or service completions at any queue. Customers arriving to queue L (L=1,2,...,n-1) must go on to queue L+1 after finishing service at server L. Customers arriving to queue n leave the system after finishing service at the last server. At queues 2 to n arrival and service rates are fixed. The objective is to minimize the expected discounted cost of the system over finite and infinite horizons. We show that the optimal policy is of threshold type. In order to establish the result, we formulate the optimal control problem as a Linear Programming. (author). 9 refs
On a multi-channel queue with state dependent input flow and interruptions
Jewgeni Dshalalow
1989-01-01
Full Text Available This paper deals with a multi-channel queueing system with a finite waiting room but without losses. The latter is achieved by a temporary interruption of the input flow activity until the waiting room is ready to place a new customer. In addition, the input flow on its busy period is non-recurrent: It is state dependent and may be controlled over relevant times of decision making. A similar model without interruptions (i.e. with losses was earlier studied by the author, where in particular, major probability characteristics of the queueing process in equilibrium were obtained. Now the author derives a simple explicit relation between the two models allowing the given queue to inherit the results previously obtained. New techniques for semi-regenerative processes are used.
A comparison of queueing, cluster and distributed computing systems
Kaplan, Joseph A.; Nelson, Michael L.
1993-01-01
Using workstation clusters for distributed computing has become popular with the proliferation of inexpensive, powerful workstations. Workstation clusters offer both a cost effective alternative to batch processing and an easy entry into parallel computing. However, a number of workstations on a network does not constitute a cluster. Cluster management software is necessary to harness the collective computing power. A variety of cluster management and queuing systems are compared: Distributed Queueing Systems (DQS), Condor, Load Leveler, Load Balancer, Load Sharing Facility (LSF - formerly Utopia), Distributed Job Manager (DJM), Computing in Distributed Networked Environments (CODINE), and NQS/Exec. The systems differ in their design philosophy and implementation. Based on published reports on the different systems and conversations with the system's developers and vendors, a comparison of the systems are made on the integral issues of clustered computing.
Packet Queueing Delay in Resilient Packet Ring Network Nodes
史国炜; 方红波; 曲建岭; 曾烈光
2004-01-01
The packet queueing delay is one of the most important performance measures of a data network and is also a significant factor to be considered in the scheduling buffer design for a network node.This paper presents a traffic queueing model for resilient packet ring (RPR) networks and a method for quantitatively analyzing queueing delays in RPR nodes.The method was used to calculate the average queueing delays of different priority traffic for different transit queue modes.The simulations show that,in the transmit direction,lower priority traffic is delayed more than higher priority traffic,and that Class-A traffic is delayed more in a single-queue ring than in a dual-queue ring.In the transit direction,the secondary transit buffer in the dual-queue ring contributes more to the traffic delay than the primary transit buffer in the single-queue ring,which in turn causes more delay than the primary transit buffer in the dual-queue ring.
''Management of customized SAT implementation'' was presented and entailed the following topics: NPP training policy; management aspects for the SAT project; project infrastructure; SAT project implementation in the context of QAP/QCP; the assembly and training of the SAT Project Team; communication and translation obstacles; project implementation strategy; initial SAT implementation for selected job positions; key considerations for the SAT project. This presentation was bases on lessons-learned from hands-on practices of SAT projects (with an involvement of international experts), publications on this topic, and recent personal experience of the instructor in this field [a very similar project has been undertaken in Russia with the joint venture of EXITECH International Training Corporation (USA) and Joint-Stock Company, ENIKO MIFI (Russia)
Environmental management activities
The Office of Environmental Management (EM) has been delegated the responsibility for the Department of Energy's (DOE's) cleanup of the nuclear weapons complex. The nature and magnitude of the waste management and environmental remediation problem requires the identification of technologies and scientific expertise from domestic and foreign sources. Within the United States, operational DOE facilities, as well as the decontamination and decommissioning of inactive facilities, have produced significant amounts of radioactive, hazardous, and mixed wastes. In order to ensure worker safety and the protection of the public, DOE must: (1) assess, remediate, and monitor sites and facilities; (2) store, treat, and dispose of wastes from past and current operations; and (3) develop and implement innovative technologies for environmental restoration and waste management. The EM directive necessitates looking beyond domestic capabilities to technological solutions found outside US borders. Following the collapse of the Soviet regime, formerly restricted elite Soviet scientific expertise became available to the West. EM has established a cooperative technology development program with Russian scientific institutes that meets domestic cleanup objectives by: (1) identifying and accessing Russian EM-related technologies, thereby leveraging investments and providing cost-savings; (2) improving access to technical information, scientific expertise, and technologies applicable to EM needs; and (3) increasing US private sector opportunities in Russian in EM-related areas
Environmental management activities
NONE
1997-07-01
The Office of Environmental Management (EM) has been delegated the responsibility for the Department of Energy`s (DOE`s) cleanup of the nuclear weapons complex. The nature and magnitude of the waste management and environmental remediation problem requires the identification of technologies and scientific expertise from domestic and foreign sources. Within the United States, operational DOE facilities, as well as the decontamination and decommissioning of inactive facilities, have produced significant amounts of radioactive, hazardous, and mixed wastes. In order to ensure worker safety and the protection of the public, DOE must: (1) assess, remediate, and monitor sites and facilities; (2) store, treat, and dispose of wastes from past and current operations; and (3) develop and implement innovative technologies for environmental restoration and waste management. The EM directive necessitates looking beyond domestic capabilities to technological solutions found outside US borders. Following the collapse of the Soviet regime, formerly restricted elite Soviet scientific expertise became available to the West. EM has established a cooperative technology development program with Russian scientific institutes that meets domestic cleanup objectives by: (1) identifying and accessing Russian EM-related technologies, thereby leveraging investments and providing cost-savings; (2) improving access to technical information, scientific expertise, and technologies applicable to EM needs; and (3) increasing US private sector opportunities in Russian in EM-related areas.
Emphasis: an active management model
The Institute of Nuclear Materials Management was founded and has grown on the basis of promoting professionalism in the nuclear industry. This paper is concerned with professional management of nuclear material. The paper introduces the reader to Emphasis, an active management model. The management model provides the framework to assist a manager in directing his available resources. Emphasis provides for establishing goals, identifying and selecting objectives, matching objectives to specific personnel, preparing and monitoring action plans, and evaluating results. The model stresses crisis prevention by systematically administering and controlling resources. A critical requirement for implementation of the model is the desire to manage, to be in charge of the situation. The nuclear industry does need managers - people who realize the sensitive nature of the industry, professionals who insist on improved performance
APPLICATIONS OF QUEUES IN HOSPITALS IN ISTANBUL
Assist.Prof. Dr. Imran Aslan
2015-01-01
Queues are one of the worst problem in hospitals in almost all World. Patients have to wait long time even to get a small operation in hospitals in Turkey. Turkey healthcare system has recently improved, but it is still not at expected level. The quantity oriented healthcare services meaning caring more patients are not good at meeting quality parameters of healthcare services. The private sector partly subsidized by governments is more profit oriented and its share has been increasing. The q...
Call packing bounds for overflow queues
van Dijk; Sluis, van der, B.
2004-01-01
Finite queueing loss systems are studied with overflow. For these systems there is no simple analytic expression for the loss probability or throughput. This paper aims to prove and promote easily computable bounds as based upon the so-called call packing principle. Under call packing a standard product form expression is available. It is proven that call packing leads to a guaranteed upper bound for the loss probability. In addition, an analytic error bound for the accuracy is derived which ...
Funnel Heap - A Cache Oblivious Priority Queue
Brodal, Gerth Stølting; Fagerberg, Rolf
2002-01-01
The cache oblivious model of computation is a two-level memory model with the assumption that the parameters of the model are unknown to the algorithms. A consequence of this assumption is that an algorithm efficient in the cache oblivious model is automatically efficient in a multi-level memory ...... an alternative optimal cache oblivious priority queue based only on binary merging. We also show that our structure can be made adaptive to different usage profiles....
Cost performance satellite design using queueing theory
Hein, G. F.
1975-01-01
The Poisson arrival model was used to determine the effects of limiting the number of channels for a disaster warning satellite. State probabilities and delay probabilities were estimated for several values of the number of channels (C) for arrival and service rates obtained from disaster warnings issued by the National Weather Service. The results predicted by the queueing model were compared with the results of a digital computer simulation.
Queues in Series in Light Traffic
Blaszczyszyn, B.; Rolski, T.
1993-01-01
We study light traffic approximations for queues in series with renewal arrivals and i.i.d. service time vectors. Formulae for limits of functions of the waiting time at different stations based on single customer effect are obtained for two approaches: dilation and thinning of the arrival process. Interdeparture times from a station possess a one-dependence property in light traffic. This paper complements previous studies of Daley and Rolski and also Asmussen's approach to light traffic lim...
On the dynamic control of matching queues
Itai Gurvich
2015-03-01
Full Text Available We consider the optimal control of matching queues with random arrivals. In this model, items arrive to dedicated queues, and wait to be matched with items from other (possibly multiple queues. A match type corresponds to the set of item classes required for a match. Once a decision has been made to perform a match, the matching itself is instantaneous and the matched items depart from the system. We consider the problem of minimizing finite-horizon cumulative holding costs. The controller must decide which matchings to execute given multiple options. In principle, the controller may choose to wait until some “inventory” of items builds up to facilitate more profitable matches in the future. We introduce a multi-dimensional imbalance process, that at each time t, is given by a linear function of the cumulative arrivals to each of the item classes. A non-zero value of the imbalance at time t means that no control could have matched all the items that arrived by time t. A lower bound based on the imbalance process can be specified, at each time point, by a solution to an optimization problem with linear constraints.While not achievable in general, this lower bound can be asymptotically approached under a dedicated item condition (an analogue of the local traffic condition in bandwidth sharing networks. We devise a myopic discrete-review matching control that asymptotically–as the arrival rates become large–achieves the imbalance-based lower bound.
Scaling of avalanche queues in directed dissipative sandpiles
Tadic; Priezzhev
2000-09-01
Using numerical simulations and analytical methods we study a two-dimensional directed sandpile automaton with nonconservative random defects (concentration c) and varying driving rate r. The automaton is driven only at the top row and driving rate is measured by the number of added particles per time step of avalanche evolution. The probability distribution of duration of elementary avalanches at zero driving rate is exactly given by P1(t,c)=t(-3/2) exp[t ln(1-c)]. For driving rates in the interval 0 server queue in the queue theory. We study scaling properties of the busy period and dissipated energy of sequences of noninterrupted activity. In the limit c-->0 and varying linear system size Lqueues are characterized by a multifractal scaling and we determine the corresponding spectral functions. For L>1/c increasing the driving rate somewhat compensates for the energy losses at defects above the line r approximately sqrt[c]. The scaling exponents of the distributions in this region of phase diagram vary approximately linearly with the driving rate. Using properties of recurrent states and the probability theory we determine analytically the exact upper bound of the probability distribution of busy periods. In the case of conservative dynamics c=0 the probability of a continuous flow increases as F(infinity) approximately r(2) for small driving rates. PMID:11088824
Environmental Management vitrification activities
Krumrine, P.H. [Waste Policy Institute, Gaithersburg, MD (United States)
1996-05-01
Both the Mixed Waste and Landfill Stabilization Focus Areas as part of the Office of Technology Development efforts within the Department of Energy`s (DOE) Environmental Management (EM) Division have been developing various vitrification technologies as a treatment approach for the large quantities of transuranic (TRU), TRU mixed and Mixed Low Level Wastes that are stored in either landfills or above ground storage facilities. The technologies being developed include joule heated, plasma torch, plasma arc, induction, microwave, combustion, molten metal, and in situ methods. There are related efforts going into development glass, ceramic, and slag waste form windows of opportunity for the diverse quantities of heterogeneous wastes needing treatment. These studies look at both processing parameters, and long term performance parameters as a function of composition to assure that developed technologies have the right chemistry for success.
Staging queues in material handling and transportation systems
Gue, Kevin R.; Kang, Keebom
2001-01-01
Proceedings of the 2001 Winter Simulation Conference B. A. Peters, J. S. Smith, D. J. Medeiros, and M. W. Rohrer, eds. In most physical queueing applications, customers join a queue andmove forward after each service, leaving room for others to join behind them. Some queues found in material handling and transportation systems do not operate like this because the queued entities (pallets or unoccupied cars, for example) are incapable of moving forward autonomously. We ...
Egalitarian Equivalence And Strategyproofness In The Queueing Problem
Youngsub Chun; Manipushpak Mitra; Suresh Mutuswami
2013-01-01
We investigate the implications of egalitarian equivalence (Pazner and Schmeidler [22]) together with queue efficiency and strategyproofness in the context of queueing problems. We completely characterize the class of mechanisms satisfying the three requirements. Though there is no mechanism in this class satisfying budget balance, feasible mechanisms exist. We also show that it is impossible to find a mechanism satisfying queue efficiency, egalitarian equivalence and a stronger notion of str...
Maximally Stabilizing Task Release Control Policy for a Dynamical Queue
Savla, Ketan; Frazzoli, Emilio
2009-01-01
In this paper, we introduce a model of dynamical queue, in which the service time depends on the server utilization history. The proposed queueing model is motivated by widely accepted empirical laws describing human performance as a function of mental arousal. The objective of this paper is to design task release control policies that can stabilize the queue for the maximum possible arrival rate, assuming deterministic arrivals. First, we prove an upper bound on the maximum possible stabiliz...
Influence of queue propagation and dissipation on route travel times
Raovic, Nevena
classes into account (Bliemer, 2008). Yperman (2007) indicates that there is a significant difference in queue-propagation and queue-dissipation between the LTM and DQM. This results in different route travel times, and can further affect route choice. In this paper, different approaches to represent...... queue propagation and dissipation through the CTM, LTM and DQM are studied. A simple network allows to show how these approaches influence route travel time. Furthermore, the possibility of changing the existing DQM is considered in order to more realistically represent queue propagation and dissipation......, which would lead to more accurate route travel times....
A single-server queue with random accumulation level
Jewgeni H. Dshalalow
1991-01-01
Full Text Available The author studies the queueing process in a single-server bulk queueing system. Upon completion of a previous service, the server can take a group of random size from customers that are available. Or, the server can wait until the queue attains a desired level. The author establishes an ergodicity criterion for both the queueing process with continuous time parameter and the imbedded process. Under this criterion, the author obtains explicit formulas for the stationary distributions of both processes by using semi-regenerative techniques.
Diffusion limits for shortest remaining processing time queues
Gromoll, H Christian; Puha, Amber L
2010-01-01
We present a heavy traffic analysis for a single server queue with renewal arrivals and generally distributed i.i.d. service times, in which the server employs the Shortest Remaining Processing Time (SRPT) policy. Under typical heavy traffic assumptions, we prove a diffusion limit theorem for a measure-valued state descriptor, from which we conclude a similar theorem for the queue length process. These results allow us to make some observations on the queue length optimality of SRPT. In particular, they provide the sharpest illustration of the well-known tension between queue length optimality and quality of service for this policy.
Diffusion limits for shortest remaining processing time queues
Amber L. Puha
2011-01-01
Full Text Available We present a heavy traffic analysis for a single server queue with renewal arrivals and generally distributed i.i.d. service times, in which the server employs the Shortest Remaining Processing Time (SRPT policy. Under typical heavy traffic assumptions, we prove a diffusion limit theorem for a measure-valued state descriptor, from which we conclude a similar theorem for the queue length process. These results allow us to make some observations on the queue length optimality of SRPT. In particular, they provide the sharpest illustration of the well-known tension between queue length optimality and quality of service for this policy.
TRANSIENT QUEUE SIZE DISTRIBUTION SOLUTION OF GEOM/G/1 QUEUE WITH FEEDBACK-A RECURSIVE METHOD
Chuanyi LUO; Yinghui TANG; Cailiang LI
2009-01-01
This paper considers the Geom/G/1 queueing model with feedback according to a late arrival system with delayed access (LASDA). Using recursive method, this paper studies the transient property of the queue size from the initial state N(0+) = I. Some new results about the recursive expression of the transient queue size distribution at any epoch n+ and the recursive formulae of the equilibrium distribution are obtained, Furthermore, the recursive formulae of the equilibrium queue size distribution at epoch n-, and n are obtained, too. The important relations between stationary queue size distributions at different epochs are discovered (being different from the relations given in M/G/1 queueing system). The model discussed in this paper can be widely applied in all kinds of communications and computer network.
Single server queueing networks with varying service times and renewal input
Pierre Le Gall
2000-01-01
Using recent results in tandem queues and queueing networks with renewal input, when successive service times of the same customer are varying (and when the busy periods are frequently not broken up in large networks), the local queueing delay of a single server queueing network is evaluated utilizing new concepts of virtual and actual delays (respectively). It appears that because of an important property, due to the underlying tandem queue effect, the usual queueing stan...
Managing hazardous activities and substances
The primary purpose of this paper is to provide background information on the process, principles and policies being employed in OECD Member Countries for managing hazardous activities (non-nuclear) and products involving chemicals (non-radioactive). In addition, the author highlights certain areas in the risk management process where certain assumptions and conclusions may be of particular relevance to the goal of a review, reconsideration and restatement of the strategy of geological disposal of radioactive wastes. (O.L.)
Queueing phase transition: theory of translation
Romano, M. Carmen; Thiel, Marco; Stansfield, Ian; Grebogi, Celso
2009-01-01
We study the current of particles on a lattice, where to each site a different hopping probability has been associated and the particles can move only in one direction. We show that the queueing of the particles behind a slow site can lead to a first-order phase transition, and derive analytical expressions for the configuration of slow sites for this to happen. We apply this stochastic model to describe the translation of mRNAs. We show that the first-order phase transition, uncovered in thi...
Decomposability queueing and computer system applications
Courtois, P J
1977-01-01
Decomposability: Queueing and Computer System Applications presents a set of powerful methods for systems analysis. This 10-chapter text covers the theory of nearly completely decomposable systems upon which specific analytic methods are based.The first chapters deal with some of the basic elements of a theory of nearly completely decomposable stochastic matrices, including the Simon-Ando theorems and the perturbation theory. The succeeding chapters are devoted to the analysis of stochastic queuing networks that appear as a type of key model. These chapters also discuss congestion problems in
2-Layered Architecture of Vague Logic Based Multilevel Queue Scheduler
Supriya Raheja
2014-01-01
Full Text Available In operating system the decisions which CPU scheduler makes regarding the sequence and length of time the task may run are not easy ones, as the scheduler has only a limited amount of information about the tasks. A good scheduler should be fair, maximizes throughput, and minimizes response time of system. A scheduler with multilevel queue scheduling partitions the ready queue into multiple queues. While assigning priorities, higher level queues always get more priorities over lower level queues. Unfortunately, sometimes lower priority tasks get starved, as the scheduler assures that the lower priority tasks may be scheduled only after the higher priority tasks. While making decisions scheduler is concerned only with one factor, that is, priority, but ignores other factors which may affect the performance of the system. With this concern, we propose a 2-layered architecture of multilevel queue scheduler based on vague set theory (VMLQ. The VMLQ scheduler handles the impreciseness of data as well as improving the starvation problem of lower priority tasks. This work also optimizes the performance metrics and improves the response time of system. The performance is evaluated through simulation using MatLab. Simulation results prove that the VMLQ scheduler performs better than the classical multilevel queue scheduler and fuzzy based multilevel queue scheduler.
Optimal grouping for a nuclear magnetic resonance scanner by means of an open queueing model
VANDAELE, Nico; VAN NIEUWENHUYSE, Inneke; Cupers, S
2003-01-01
In this paper we analyze how a nuclear magnetic resonance scanner can be managed more efficiently, simultaneously improving patient comfort (in terms of total time spent in the system) and increasing availability in case of emergency calls. By means of a superposition approach, all relevant data on the arrival and service process of different patient types are transformed into a general single server, single class queueing model. The objective function consists of the weighted average patient...
Asymptotic inference for waiting times and patiences in queues with abandonment
Gorst-Rasmussen, Anders; Hansen, Martin Bøgsted
2008-01-01
Motivated by applications in call center management, we propose a framework based on empirical process techniques for inference about the waiting time and patience distribution in multiserver queues with abandonment. The framework rigorises heuristics based on survival analysis of independent and identically distributed observations by allowing correlated successive waiting times. Assuming a regenerative structure of the sequence of offered waiting times, we establish asymptotic properties of...
Peter Wanke
2011-01-01
The ship-berth link is one of the most critical aspects to be managed at port operations. Until now, simulation models have considered the impact of queue priorities, such as size and type of ships, on waiting times. This research differentiates from previous studies not only by considering another variable - the demurrage cost for each type of ship -, but also by considering the possibility of different berth allocation policies. It reports on a simulation study on small Brazilian private co...
Queues with Dropping Functions and General Arrival Processes.
Chydzinski, Andrzej; Mrozowski, Pawel
2016-01-01
In a queueing system with the dropping function the arriving customer can be denied service (dropped) with the probability that is a function of the queue length at the time of arrival of this customer. The potential applicability of such mechanism is very wide due to the fact that by choosing the shape of this function one can easily manipulate several performance characteristics of the queueing system. In this paper we carry out analysis of the queueing system with the dropping function and a very general model of arrival process--the model which includes batch arrivals and the interarrival time autocorrelation, and allows for fitting the actual shape of the interarrival time distribution and its moments. For such a system we obtain formulas for the distribution of the queue length and the overall customer loss ratio. The analytical results are accompanied with numerical examples computed for several dropping functions. PMID:26943171
Transient Solution of the M/M/C1 Queue with Additional C2 Servers for Longer Queues and Balking
R. O. Al-Seedy
2008-01-01
Full Text Available The goal of this research is to discuss the M/M/C1 queue with additional C2 servers for longer queues and balking. By using generating function technique the transient probabilities are derived in terms of the modified Bessel function.
Randomized Scheduling Algorithm for Queueing Networks
Shah, Devavrat
2009-01-01
There has recently been considerable interest in design of low-complexity, myopic, distributed and stable scheduling policies for constrained queueing network models that arise in the context of emerging communication networks. Here, we consider two representative models. One, a model for the collection of wireless nodes communicating through a shared medium, that represents randomly varying number of packets in the queues at the nodes of networks. Two, a buffered circuit switched network model for an optical core of future Internet, to capture the randomness in calls or flows present in the network. The maximum weight scheduling policy proposed by Tassiulas and Ephremide in 1992 leads to a myopic and stable policy for the packet-level wireless network model. But computationally it is very expensive (NP-hard) and centralized. It is not applicable to the buffered circuit switched network due to the requirement of non-premption of the calls in the service. As the main contribution of this paper, we present a st...
Data Model Approach And Markov Chain Based Analysis Of Multi-Level Queue Scheduling
Diwakar Shukla
2010-01-01
Full Text Available There are many CPU scheduling algorithms inliterature like FIFO, Round Robin, Shortest-Job-First and so on.The Multilevel-Queue-Scheduling is superior to these due to itsbetter management of a variety of processes. In this paper, aMarkov chain model is used for a general setup of Multilevelqueue-scheduling and the scheduler is assumed to performrandom movement on queue over the quantum of time.Performance of scheduling is examined through a rowdependent data model. It is found that with increasing value of αand d, the chance of system going over the waiting state reduces.At some of the interesting combinations of α and d, it diminishesto zero, thereby, provides us some clue regarding better choice ofqueues over others for high priority jobs. It is found that ifqueue priorities are added in the scheduling intelligently thenbetter performance could be obtained. Data model helpschoosing appropriate preferences.
Performance optimization of queueing systems with perturbation realization
Xia, Li
2012-04-01
After the intensive studies of queueing theory in the past decades, many excellent results in performance analysis have been obtained, and successful examples abound. However, exploring special features of queueing systems directly in performance optimization still seems to be a territory not very well cultivated. Recent progresses of perturbation analysis (PA) and sensitivity-based optimization provide a new perspective of performance optimization of queueing systems. PA utilizes the structural information of queueing systems to efficiently extract the performance sensitivity information from a sample path of system. This paper gives a brief review of PA and performance optimization of queueing systems, focusing on a fundamental concept called perturbation realization factors, which captures the special dynamic feature of a queueing system. With the perturbation realization factors as building blocks, the performance derivative formula and performance difference formula can be obtained. With performance derivatives, gradient-based optimization can be derived, while with performance difference, policy iteration and optimality equations can be derived. These two fundamental formulas provide a foundation for performance optimization of queueing systems from a sensitivity-based point of view. We hope this survey may provide some inspirations on this promising research topic. © 2011 Elsevier B.V. All rights reserved.
A large deviation principle for join the shortest queue
Puhalskii, Anatolii A.; Vladimirov, Alexander A.
2005-01-01
We consider a join-the-shortest-queue model which is as follows. There are $K$ single FIFO servers and $M$ arrival processes. The customers from a given arrival process can be served only by servers from a certain subset of all servers. The actual destination is the server with the smallest weighted queue length. The arrival processes are assumed to obey a large deviation principle while the service is exponential. A large deviation principle is established for the queue-length process. The a...
Practical memory checkers for stacks, queues and deques
Fischlin, Marc
2005-01-01
A memory checker for a data structure provides a method to check that the output of the data structure operations is consistent with the input even if the data is stored on some insecure medium. In [8] we present a general solution for all data structures that are based on insert(i,v) and delete(j) commands. In particular this includes stacks, queues, deques (double-ended queues) and lists. Here, we describe more time and space efficient solutions for stacks, queues and deques. Each algorithm...
Optimal queue-size scaling in switched networks
Shah, D; Walton, N. S.; Zhong, Y
2011-01-01
We consider a switched (queuing) network in which there are constraints on which queues may be served simultaneously; such networks have been used to effectively model input-queued switches and wireless networks. The scheduling policy for such a network specifies which queues to serve at any point in time, based on the current state or past history of the system. In the main result of this paper, we provide a new class of online scheduling policies that achieve optimal queue-size scaling for ...
一种基于排队论的主动队列拥塞控制算法%A New Congestion Control Algorithm for Active Queue Based on Queuing Theory
闫英战; 田立伟
2012-01-01
AQM algorithm has many deficiencies, such as a large queuing delay, strong delay jitter, the rate of the data into and out the team not matched, and thus it always leads to data retention, loss and oscillation. Based on this, the M/M/m (n) queuing system thought based on the BLUE algorithm is introduced which is called PBLUE. The algorithm ensures the stability of the queue length according to equilibrium equation under stable state. Meanwhile , it increases the expansion factor and adjusts the router's cache for quickly recovering of the lost data. In the simulation, the improved algorithm reduced the packet loss rate and increased the bandwidth utilization and stabled the queue length.%主动队列(AQM)算法存在诸多的不足,如排队延时大、时延抖动性强、数据进队与出队速率不匹配等,从而导致数据的滞留、丢失和振荡.基于此,在BLUE算法的基础上,引入M/M/m (n)排队系统的思想,提出一种新的算法——PBLUE.该算法根据稳定状态下的平衡方程来保证队列长度的稳定性,增加扩充因子调节路由器的缓存来快速恢复丢失的数据.通过仿真实验,改进的算法降低了丢包率,提高了带宽利用率,并稳定了队列长度.
Optimal Stopping of Active Portfolio Management
Kyoung Jin Choi; Hyeng Keun Koo; Do Young Kwak
2004-01-01
We study an investor¡¯s decision to switch from active portfolio management to passive management. This problem is mathematically modelled by a mixture of a consumption-portfolio selection problem and an optimal stopping problem. We assume that the investor has stochastic differential utility with ambiguity aversion and incurs utility loss from active portfolio management that can be avoided by switching to passive management, and show that she manages actively as long as her level of wealth ...
Simple queueing approach to segregation dynamics in Schelling model
Sobkowicz, Pawel
2007-01-01
A simple queueing approach for segregation of agents in modified one dimensional Schelling segregation model is presented. The goal is to arrive at simple formula for the number of unhappy agents remaining after the segregation.
Opportunistic Channel Scheduling for Ad Hoc Networks with Queue Stability
Dong, Lei; Wang, Yongchao
2015-03-01
In this paper, a distributed opportunistic channel access strategy in ad hoc network is proposed. We consider the multiple sources contend for the transmission opportunity, the winner source decides to transmit or restart contention based on the current channel condition. Owing to real data assumption at all links, the decision still needs to consider the stability of the queues. We formulate the channel opportunistic scheduling as a constrained optimization problem which maximizes the system average throughput with the constraints that the queues of all links are stable. The proposed optimization model is solved by Lyapunov stability in queueing theory. The successive channel access problem is decoupled into single optimal stopping problem at every frame and solved with Lyapunov algorithm. The threshold for every frame is different, and it is derived based on the instantaneous queue information. Finally, computer simulations are conducted to demonstrate the validity of the proposed strategy.
Networks of multi-server queues with parallel processing
Bonald, Thomas; Comte, Céline
2016-01-01
We consider a network of multi-server queues wherein each job can be processed in parallel by any subset of servers within a pre-defined set that depends on its class. Each server is allocated in FCFS order at each queue. Jobs arrive according to Poisson processes, have independent exponential service requirements and are routed independently at random. We prove that, when stable, the network has a product-form stationary distribution. From a practical perspective, we propose an algorithm on ...
Waiting time distribution in M/D/1 queueing systems
Iversen, Villy Bæk; Staalhagen, Lars
1999-01-01
The well-known formula for the waiting time distribution of M/D/1 queueing systems is numerically unsuitable when the load is close to 1.0 and/or the results for a large waiting time are required. An algorithm for any load and waiting time is presented, based on the state probabilities of M/D/1....... The principles are also applicable for other queueing systems...
Herding in Queues with Waiting Costs: Rationality and Regret
Senthil K. Veeraraghavan; Laurens G. Debo
2011-01-01
We study how consumers with waiting cost disutility choose between two congested services of unknown service value. Consumers observe an imperfect private signal indicating which service facility may provide better service value as well as the queue lengths at the service facilities before making their choice. If more consumers choose the same service facility because of their private information, longer queues will form at that facility and indicate higher quality. On the other hand, a long ...
A message queue based event notification system : football lottery system
Xu, Yunpeng
2010-01-01
The event notification service enables user of getting informed about the occurrence of their events of interest. Message queue technology provides asynchronous message exchange functions between computer processes. This thesis presents a solution of building event notification system using the message queue approach. The events in the experiment are generated during the football match and used for both stateless and stateful processing. The system includes three main applic...
A queueing network model to analyze the impact of parallelization of care on patient cycle time.
Jiang, Lixiang; Giachetti, Ronald E
2008-09-01
The total time a patient spends in an outpatient facility, called the patient cycle time, is a major contributor to overall patient satisfaction. A frequently recommended strategy to reduce the total time is to perform some activities in parallel thereby shortening patient cycle time. To analyze patient cycle time this paper extends and improves upon existing multi-class open queueing network model (MOQN) so that the patient flow in an urgent care center can be modeled. Results of the model are analyzed using data from an urgent care center contemplating greater parallelization of patient care activities. The results indicate that parallelization can reduce the cycle time for those patient classes which require more than one diagnostic and/ or treatment intervention. However, for many patient classes there would be little if any improvement, indicating the importance of tools to analyze business process reengineering rules. The paper makes contributions by implementing an approximation for fork/join queues in the network and by improving the approximation for multiple server queues in both low traffic and high traffic conditions. We demonstrate the accuracy of the MOQN results through comparisons to simulation results. PMID:18826003
Queue-based random-access algorithms: Fluid limits and stability issues
Javad Ghaderi
2014-09-01
Full Text Available We use fluid limits to explore the (instability properties of wireless networks with queue-based random-access algorithms. Queue-based random-access schemes are simple and inherently distributed in nature, yet provide the capability to match the optimal throughput performance of centralized scheduling mechanisms in a wide range of scenarios. Unfortunately, the type of activation rules for which throughput optimality has been established, may result in excessive queue lengths and delays. The use of more aggressive/persistent access schemes can improve the delay performance, but does not offer any universal maximum-stability guarantees. In order to gain qualitative insight and investigate the (instability properties of more aggressive/persistent activation rules, we examine fluid limits where the dynamics are scaled in space and time. In some situations, the fluid limits have smooth deterministic features and maximum stability is maintained, while in other scenarios they exihibit random oscillatory characteristics, giving rise to major technical challenges. In the latter regime, more aggressive access schemes continue to provide maximum stability in some networks, but may cause instability in others. In order to prove that, we focus on a particular network example and conduct a detailed analysis of the fluid limit process for the associated Markov chain. Specifically, we develop a novel approach based on stopping time sequences to deal with the switching probabilities governing the sample paths of the fluid limit process. Simulation experiments are conducted to illustrate and validate the analytical results.
Two Coupled Queues with Vastly Different Arrival Rates: Critical Loading Case
Charles Knessl
2011-01-01
Full Text Available We consider two coupled queues with a generalized processor sharing service discipline. The second queue has a much smaller Poisson arrival rate than the first queue, while the customer service times are of comparable magnitude. The processor sharing server devotes most of its resources to the first queue, except when it is empty. The fraction of resources devoted to the second queue is small, of the same order as the ratio of the arrival rates. We assume that the primary queue is heavily loaded and that the secondary queue is critically loaded. If we let the small arrival rate to the secondary queue be O(ε, where 0≤ε≪1, then in this asymptotic limit the number of customers in the first queue will be large, of order O(ε-1, while that in the second queue will be somewhat smaller, of order O(ε-1/2. We obtain a two-dimensional diffusion approximation for this model and explicitly solve for the joint steady state probability distribution of the numbers of customers in the two queues. This work complements that in (Morrison, 2010, which the second queue was assumed to be heavily or lightly loaded, leading to mean queue lengths that were O(ε-1 or O(1, respectively.
Upper Bounds on Performance Measures of Heterogeneous // Queues
F. S. Q. Alves
2011-01-01
Full Text Available In many real-life queueing systems, the servers are often heterogeneous, namely they work at different rates. This paper provides a simple method to compute tight upper bounds on two important performance measures of single-class heterogeneous multi-server Markovian queueing systems, namely the average number in queue and the average waiting time in queue. This method is based on an expansion of the state space that is followed by an approximate reduction of the state space, only considering the most probable states. In most cases tested, we were able to approximate the actual behavior of the system with smaller errors than those obtained from traditional homogeneous multiserver Markovian queues, as shown by GPSS simulations. In addition, we have correlated the quality of the approximation with the degree of heterogeneity of the system, which was evaluated using its Gini index. Finally, we have shown that the bounds are robust and still useful, even considering quite different allocation strategies. A large number of simulation results show the accuracy of the proposed method that is better than that of classical homogeneous multiserver Markovian formulae in many situations.
The Diseconomies of Queue Pooling: An Empirical Investigation of Emergency Department Length of Stay
Song, Hummy; Tucker, Anita Lynn; Murrell, Karen L
2014-01-01
We conduct an empirical investigation of the impact of two different queue management systems on throughput times. Using an Emergency Department’s (ED) patient-level data (N = 231,081) from 2007 to 2010, we find that patients’ lengths of stay (LOS) were longer when physicians were assigned patients under a pooled queuing system, compared to when each physician operated under a dedicated queuing system. The dedicated queuing system resulted in a 10 percent decrease in LOS—a 32-minute reduction...
IMPLEMENTATION OF CENTRAL QUEUE BASED REALTIME SCHEDULER FOR MULTIPLE SOURCE DATA STREAMING
V. Kaviha
2014-01-01
Full Text Available Real-time data packet sources are required to remain robust against different security threats. This study proposes a real-time secure scheduling strategy for data transmission to enhance the communication throughput and reduce the overheads. The proposed system combines real-time scheduling with security service enhancement, error detection and realtime scheduler based on EDF algorithm using uc/os-II real time operating system, implemented on cortex M3 processor. The scheduling unit uses central queue management model and the security enhancement scheme adopts a blowfish encryption mechanism.
Asymptotic inference for waiting times and patiences in queues with abandonment
Gorst-Rasmussen, Anders; Hansen, Martin Bøgsted
2009-01-01
Motivated by applications in call center management, we propose a framework based on empirical process techniques for inference about waiting time and patience distributions in multiserver queues with abandonment. The framework rigorises heuristics based on survival analysis of independent and...... identically distributed observations by allowing correlated waiting times. Assuming a regenerative structure of offered waiting times, we establish asymptotic properties of estimators of limiting distribution functions and derived functionals. We discuss construction of bootstrap confidence intervals and...... statistical tests, including a simple bootstrap two-sample test for comparing patience distributions. A small simulation study and a real data example are presented....
An introduction to queueing theory modeling and analysis in applications
Bhat, U Narayan
2015-01-01
This introductory textbook is designed for a one-semester course on queueing theory that does not require a course on stochastic processes as a prerequisite. By integrating the necessary background on stochastic processes with the analysis of models, the work provides a sound foundational introduction to the modeling and analysis of queueing systems for a wide interdisciplinary audience of students in mathematics, statistics, and applied disciplines such as computer science, operations research, and engineering. This edition includes additional topics in methodology and applications. Key features: • An introductory chapter including a historical account of the growth of queueing theory in more than 100 years. • A modeling-based approach with emphasis on identification of models. • Rigorous treatment of the foundations of basic models commonly used in applications with appropriate references for advanced topics. • Applications in manufacturing and, computer and communication systems. • A chapter on ...
Bulk input queues with quorum and multiple vacations
Dshalalow Jewgeni H.
1996-01-01
Full Text Available The authors study a single-server queueing system with bulk arrivals and batch service in accordance to the general quorum discipline: a batch taken for service is not less than r and not greater than R ( ≥ r . The server takes vacations each time the queue level falls below r ( ≥ 1 in accordance with the multiple vacation discipline. The input to the system is assumed to be a compound Poisson process. The analysis of the system is based on the theory of first excess processes developed by the first author. A preliminary analysis of such processes enabled the authors to obtain all major characteristics for the queueing process in an analytically tractable form. Some examples and applications are given.
Bulk input queues with quorum and multiple vacations
Jewgeni H. Dshalalow
1996-01-01
Full Text Available The authors study a single-server queueing system with bulk arrivals and batch service in accordance to the general quorum discipline: a batch taken for service is not less than r and not greater than R(≥r. The server takes vacations each time the queue level falls below r(≥1 in accordance with the multiple vacation discipline. The input to the system is assumed to be a compound Poisson process. The analysis of the system is based on the theory of first excess processes developed by the first author. A preliminary analysis of such processes enabled the authors to obtain all major characteristics for the queueing process in an analytically tractable form. Some examples and applications are given.
Queue Stability and Probability 1 Convergence via Lyapunov Optimization
Neely, Michael J
2010-01-01
Lyapunov drift and Lyapunov optimization are powerful techniques for optimizing time averages in stochastic queueing networks subject to stability. However, there are various definitions of queue stability in the literature, and the most convenient Lyapunov drift conditions often provide stability and performance bounds only in terms of a time average expectation, rather than a pure time average. We extend the theory to show that for quadratic Lyapunov functions, the basic drift condition implies all major forms of stability. Further, we show that the basic drift-plus-penalty condition implies that the same bounds for queue backlog and penalty expenditure that are known to hold for time average expectations also hold for pure time averages with probability 1. Our analysis combines Lyapunov drift theory with the Kolmogorov law of large numbers for martingale differences with finite variance.
The single server queue and the storage model: Large deviations and fixed points
Moez Draief
2006-04-01
Full Text Available We consider the coupling of a single server queue and a storage model defined as a queue/store model. We establish that if the input variables, arrivals at the queue and store, satisfy large deviations principles and are linked through an exponential tilting, then the output variables (departures from each system satisfy large deviations principles with the same rate function.
A Complexity O(1) Priority Queue for Event Driven Molecular Dynamics Simulations
Paul, Gerald
2006-01-01
We propose and implement a priority queue suitable for use in event driven molecular dynamics simulations. All operations on the queue take on average O(1) time per collision. In comparison, previously studied queues for event driven molecular dynamics simulations require O(log $N$) time per collision for systems of $N$ particles.
Bulk input queues with quorum and multiple vacations
Dshalalow Jewgeni H.; Yellen Jay
1996-01-01
The authors study a single-server queueing system with bulk arrivals and batch service in accordance to the general quorum discipline: a batch taken for service is not less than r and not greater than R ( ≥ r ) . The server takes vacations each time the queue level falls below r ( ≥ 1 ) in accordance with the multiple vacation discipline. The input to the system is assumed to be a compound Poisson process. The analysis of the system is based on the theory of first ...
Service Differentiation in Cognitive Radio Networks: A Priority Queueing Model
Azarfar, Arash; Sansò, Brunilde
2012-01-01
The popularity of opportunistic spectrum access (OSA), implemented by cognitive radios (CRs), necessitates that these networks should be able to provide service differentiation for different classes of traffic. One of the classic schemes for such a goal is through priority queueing. As link interruptions in OSA networks are frequent, we discuss in this paper four priority queueing disciplines in the presence of interruptions: preemptive-resume, non-preemptive, exceptional non-preemptive and preemptive in case of occurrence of an interruption. Analytical results, in addition to simulation results to validate their accuracy, are provided.
Lattice path counting and the theory of queues
Böhm, Walter
2008-01-01
In this paper we will show how recent advances in the combinatorics of lattice paths can be applied to solve interesting and nontrivial problems in the theory of queues. The problems we discuss range from classical ones like M^a/M^b/1 systems to open tandem systems with and without global blocking and to queueing models that are related to random walks in a quarter plane like the Flatto-Hahn model or systems with preemptive priorities. (author´s abstract)
Queues with equally heavy sojourn time and service requirement distributions
Núñez Queija, Rudesindo (Sindo)
2002-01-01
For the G/G/1 queue with First-Come First-Served, it is well known that the tail of the sojourn time distribution is heavier than the tail of the service requirement distribution when the latter has a regularly varying tail. In contrast, for the M/G/1 queue with Processor Sharing, Zwart and Boxma showed that under the same assumptions on the service requirement distribution, the two tails are ``equally heavy''. By means of a probabilistic analysis we provide a new insightful proof of this res...
Active Risk Management and Banking Stability
Silva Buston, C.F.
2013-01-01
Abstract: This paper analyzes the net impact of two opposing effects of active risk management at banks on their stability: higher risk-taking incentives and better isolation of credit supply from varying economic conditions. We present a model where banks actively manage their portfolio risk by buy
Efficient Simulation of Population Overflow in Parallel Queues
Nicola, Victor F.; Zaburnenko, Tatiana S.
2006-01-01
In this paper we propose a state-dependent importance sampling heuristic to estimate the probability of population overﬂow in networks of parallel queues. This heuristic approximates the “optimal” state-dependent change of measure without the need for difﬁcult mathematical analysis or costly optimiz
The Exactly Solvable Simplest Model for Queue Dynamics
Sugiyama, Y.; Yamada, H.
1996-01-01
We present an exactly solvable model for queue dynamics. Our model is very simple but provides the essential property for such dynamics. As an example, the model has the traveling cluster solution as well as the homogeneous flow solution. The model is the limiting case of Optimal Velocity (OV) model, which is proposed for the car following model to induce traffic jam spontaneously.
Algorithm for queueing networks with multi-rate traffic
Iversen, Villy Bæk; Ko, King-Tim
2011-01-01
the nodes behave as independent nodes. For closed queueing networks with multiple servers in every node and multi-rate services we may apply multidimensional convolution algorithm to aggregate the nodes so that we end up with two nodes, the aggregated node and a single node, for which we can calculate...
Algorithm for queueing networks with multi-rate traffic
Iversen, Villy Bæk; King-Tim, Ko
2011-01-01
the nodes behave as independent nodes. For closed queueing networks with multiple servers in every node and multi-rate services we may apply multidimensional convolutions to aggregate the nodes so that we end up with two nodes, the aggregated node and a single node, for which we can calculate the detailed...
Python for Scientific Computing Education: Modeling of Queueing Systems
Vladimiras Dolgopolovas
2014-01-01
Full Text Available In this paper, we present the methodology for the introduction to scientific computing based on model-centered learning. We propose multiphase queueing systems as a basis for learning objects. We use Python and parallel programming for implementing the models and present the computer code and results of stochastic simulations.
Python for Scientific Computing Education: Modeling of Queueing Systems
Vladimiras Dolgopolovas; Valentina Dagienė; Saulius Minkevičius; Leonidas Sakalauskas
2014-01-01
In this paper, we present the methodology for the introduction to scientific computing based on model-centered learning. We propose multiphase queueing systems as a basis for learning objects. We use Python and parallel programming for implementing the models and present the computer code and results of stochastic simulations.
A note on queues with $M/G/\\infty$ input
Mandjes, Michel
2001-01-01
We consider a fluid queue fed by sessions, arriving according to a Poisson process; a session has a heavy-tailed duration, during which traffic is sent at a constant rate. We scale Poisson input rate $\\Lambda$, buffer space $B$, and link rate $C$ by $n$, such that we get $n\\lambda$, $nb$, and $nc$,
Maximally Stabilizing Admission Control Policy for a Dynamical Queue
Savla, Ketan
2009-01-01
In this paper, we consider the following stability problem for a novel dynamical queue. Independent and identical tasks arrive for a queue at a deterministic rate. The server spends deterministic state-dependent times to service these tasks, where the server state is governed by its utilization history through a simple dynamical model. Inspired by empirical laws for human performance as a function of mental arousal, we let the service time be related to the server state by a continuous convex function. We consider an admission control architecture which regulates task entry into service. The objective in this paper is to design such admission control policies that can stabilize the dynamical queue for the maximum possible arrival rate, where the queue is said to be stable if the number of tasks awaiting service does not grow unbounded over time. First, we prove an upper bound on the maximum stabilizable arrival rate for any admission control policy by postulating a notion of one-task equilibrium for the dynam...
Job Queues, Certification Status, and the Education Labor Market
Evans, Lorraine
2011-01-01
This research explores the interaction between training programs and certification status in one education labor market to examine the micro-level interactions that shape the recruitment process. Using job queue theory, it is found that the information available to novice teachers operates to stratify and shape their worksite choices in addition…
Improvement of active queue management for VOIP QoS%队列管理算法对VOIP QoS的提高
王笑妍
2013-01-01
Voice over IP (VoIP) has become increasingly popular over the IP network, Nevertheless, these real-time traffic may experience less than desirable quality, and the performance is unsatisfactory particularly when the link is congested. This paper presents a method of improving the QoS of real-time audio over IP network infrastructure at low service cost and with no changes to the existing network. A thorough study of RED' s effects on voice over IP is given, concluding that RED is able to control the delay distribution, jitter and effective loss of VoIP.%VoIP日益成为受用户欢迎的IP网络服务,然而,这些IP网络上的VOIP通话质量却并不能得到令人满意的保证,尤其是当网络拥塞的时候.文中提出了一种不涉及改造网络结构,低成本地提高VOIP的通话质量的方法.通过随机早期检测算法的应用,可以有效地降低VOIP通话的延迟、抖动和有效丢包率,从而提高VOIP的通话质量.
Organizational Actively Management for Opportunity Hunting
Nasser Fegh-hi FARAHMAND
2012-03-01
Full Text Available Organizational Actively Management (OAM is the responsibility of every manager. Because, an approach for OAM is becoming more widely accepted is a community-based development approach. In Opportunity Hunting Approach (OHA, OAM is the responsibility of every manager for his/her actions. OAM is using from top to bottom development model. According to the survey of market and customers, after understand customers’ needs, organization then decide how the quality policy and target will develop, from there the actively management system can be developed. The aim of this study in field of organizational actively management and policy of it can provide the specific process required for setting up and monitoring the actively target. As it also is customer-oriented, it aims to improve customer satisfaction. In addition, the actively target should be set up and implemented within every organization department and at each level, in accordance with actively policy. Furthermore, organization should develop the actively management system, in order to conform to general requirements and actively target.
C. KANDEMIR-CAVAS
2012-12-01
Full Text Available Aquarium originated marine green alga Caulerpa taxifolia was introduced into the Mediterranean Sea accidentally in 1984. This invasion has been negatively affecting the sub-littoral ecosystem of the Mediterranean. One of the important reasons for its success in the Mediterranean is its secondary toxic metabolite called caulerpenyne (CPN. Furthermore, CPN has anti-proliferative and apoptotic activities, therefore, CPN can be considered as a potential native source in cancer therapy. For that reason, modeling this metabolite might be of importance. Increase and decrease of the CPN level before reaching the critical level can be expressed by means of a queueing system in which the number of ‘customers' increases and decreases. In fact, production of CPN shows fluctuations for many environmental reasons, which allow us to apply queueing theory. In the present study, the expected time to reach the maximum caulerpenyne level was analyzed and evaluated using queueing theory.
Optimal Server Assignment in Multi-Server Queueing Systems with Random Connectivities
Halabian, Hassan; Lung, Chung-Horng
2011-01-01
In this paper, we investigate the problem of assignment of $K$ identical servers to a set of $N$ parallel queues in a time slotted queueing system. The connectivity of each queue to each server is randomly changing with time; each server can serve at most one queue and each queue can be served by at most one server per time slot. Such multi-server queueing systems were widely applied in modeling the scheduling (or resource allocation) problem in wireless networks. It has been previously proven that Maximum Weighted Matching (MWM) is a throughput optimal server assignment policy for such queueing systems. In this paper, first we prove that for a symmetric system with i.i.d. Bernoulli packet arrivals and connectivities, MWM minimizes, in stochastic ordering sense, a broad range of cost functions of the queue lengths including total queue occupancy (or equivalently minimizes the average queueing delay). Then, we extend the model by considering imperfect services where it is assumed that the service of a schedule...
Fuzzy-Based Dynamic Distributed Queue Scheduling for Packet Switched Networks
Chollette C.Chude-Olisah; Uche A.K.Chude-Okonkwo; Kamalrulnizam A.Balar; Ghazali Sulong
2013-01-01
Addressing the problem of queue scheduling for the packet-switched system is a vital aspect of congestion control.In this paper,the fuzzy logic based decision method is adopted for queue scheduling in order to enforce some level of control for traffic of different quality of service requirements using predetermined values.The fuzzy scheduler proposed in this paper takes into account the dynamic nature of the Internet traffic with respect to its time-varying packet arrival process that affects the network states and performance.Three queues are defined,viz low,medium and high priority queues.The choice of prioritizing packets influences how queues are served.The fuzzy scheduler not only utilizes queue priority in the queue scheduling scheme,but also considers packet drop susceptibility and queue limit.Through simulation it is shown that the fuzzy scheduler is more appropriate for the dynamic nature of Internet traffic in a packet-switched system as compared with some existing queue scheduling methods.Results show that the scheduling strategy of the proposed fuzzy scheduler reduces packet drop,provides good link utilization and minimizes queue delay as compared with the priority queuing (PQ),first-in-first-out (FIFO),and weighted fair queuing (WFQ).
Elements of queueing theory palm martingale calculus and stochastic recurrences
Baccelli, François
2003-01-01
The Palm theory and the Loynes theory of stationary systems are the two pillars of the modern approach to queuing. This book, presenting the mathematical foundations of the theory of stationary queuing systems, contains a thorough treatment of both of these. This approach helps to clarify the picture, in that it separates the task of obtaining the key system formulas from that of proving convergence to a stationary state and computing its law. The theory is constantly illustrated by classical results and models: Pollaczek-Khintchin and Tacacs formulas, Jackson and Gordon-Newell networks, multiserver queues, blocking queues, loss systems etc., but it also contains recent and significant examples, where the tools developed turn out to be indispensable. Several other mathematical tools which are useful within this approach are also presented, such as the martingale calculus for point processes, or stochastic ordering for stationary recurrences. This thoroughly revised second edition contains substantial addition...
COOPERATIVE DYNAMICS OF LOYAL CUSTOMERS IN QUEUEING NETWORKS
Olivier GALLAY; Max-Olivier HONGLER
2008-01-01
We consider queueing networks (QN's) with feedback loops roamed by "intelligent" agents, able to select their routing on the basis of their measured waiting times at the QN nodes. This is an idealized model to discuss the dynamics of customers who stay loyal to a service supplier, provided their service time remains below a critical threshold. For these QN's, we show that the traffic flows may exhibit collective patterns typically encountered in multi-agent systems. In simple network topologies, the emergent cooperative behaviors manifest themselves via stable macroscopic temporal oscillations, synchronization of the queue contents and stabilization by noise phenomena. For a wide range of control parameters, the underlying presence of the law of large numbers enables us to use deterministic evolution laws to analytically characterize the cooperative evolution of our multi-agent systems. In particular, we study the case where the servers are sporadically subject to failures altering their ordinary behavior.
Transient Analysis of Hysteresis Queueing Model Using Matrix Geometric Method
Wajiha Shah
2011-10-01
Full Text Available Various analytical methods have been proposed for the transient analysis of a queueing system in the scalar domain. In this paper, a vector domain based transient analysis is proposed for the hysteresis queueing system with internal thresholds for the efficient and numerically stable analysis. In this system arrival rate of customer is controlled through the internal thresholds and the system is analyzed as a quasi-birth and death process through matrix geometric method with the combination of vector form Runge-Kutta numerical procedure which utilizes the special matrices. An arrival and service process of the system follows a Markovian distribution. We analyze the mean number of customers in the system when the system is in transient state against varying time for a Markovian distribution. The results show that the effect of oscillation/hysteresis depends on the difference between the two internal threshold values.
Worst-case efficient external-memory priority queues
Brodal, Gerth Stølting; Katajainen, Jyrki
A priority queue Q is a data structure that maintains a collection of elements, each element having an associated priority drawn from a totally ordered universe, under the operations Insert, which inserts an element into Q, and DeleteMin, which deletes an element with the minimum priority from Q....... In this paper a priority-queue implementation is given which is efficient with respect to the number of block transfers or I/Os performed between the internal and external memories of a computer. Let B and M denote the respective capacity of a block and the internal memory measured in elements. The...... developed data structure handles any intermixed sequence of Insert and DeleteMin operations such that in every disjoint interval of B consecutive priorityqueue operations at most clogM/B N/M I/Os are performed, for some positive constant c. These I/Os are divided evenly among the operations: if B ≥ clog...
Pricing Analysis in Geo/Geo/1 Queueing System
Yan Ma
2015-01-01
Full Text Available This paper studies the equilibrium behavior of customers and optimal pricing strategies of servers in a Geo/Geo/1 queueing system. Two common pricing mechanisms are considered. The first one is called ex-post payment (EPP scheme where the server collects tolls proportional to queue times, and the second one is called ex-ante payment (EAP scheme where the server charges a flat fee for the total service. The server sets the toll price to maximize its own profit. It is found that, under a customer’s choice equilibrium, the two toll mechanisms are equivalent from the economic point of view. Finally, we present several numerical experiments to investigate the effects of system parameters on the equilibrium customer joining rate and servers’ profits.
The Effect of Queueing Strategy on Network Traffic
In recent years, the transportation system has been faced by increasing challenge in congestion and inefficiency, and research in traffic network has become a significant area of interest. In this paper, we introduce a dynamic-information-based (DIB) queueing strategy into network traffic model under the efficient routing strategy. DIB makes a packet with higher priority to be delivered if there are less packets travelling along its path from the current node to the destination. It is found that, compared with the traditional first-in-first-out (FIFO) queueing strategy, DIB can effectively balance the traffic load of the system via delaying packets to be delivered to congested nodes. Although the network capacity has no obvious changes, some other indexes which reflect transportation efficiency are efficiently improved in the congestion state. Besides, extensive simulation results and discussions are provided to explain the phenomena. The results may provide novel insights for research on traffic systems. (condensed matter: structural, mechanical, and thermal properties)
Entrainment of a Synthetic Oscillator through Queueing Coupling
Hochendoner, Philip; Mather, William; Butzin, Nicholas; Ogle, Curtis
2014-03-01
Many biological systems naturally exhibit (often noisy) oscillatory patterns that are capable of being entrained by external stimuli, though the mechanism of entrainment is typically obscured by the complexity of native networks. A synthetic biology approach, where genetic programs are wired ``by hand,'' has proven useful in this regard. In the present study, we use a synthetic oscillator in Escherichia coli to demonstrate a novel and potentially widespread mechanism for biological entrainment: competition of proteins for degradation by common pathway, i.e. a entrainment by a bottleneck. To faithfully represent the discrete and stochastic nature of this bottleneck, we leverage results from a recent biological queueing theory, where in particular, the queueing theoretic concept of workload is discovered to simplify the analysis. NSF Award 1330180.
A unified approach to fast teller queues and ATM
BECK, B.; Dabrowski, A R; McDonald, D. R.
1999-01-01
This paper examines a problem of importance to the telecommunications industry. In the design of modern ATM switches, it is necessary to use simulation to estimate the probability that a queue within the switch exceeds a given large value. Since these are extremely small probabilities, importance sampling methods must be used. Here we obtain a change of measure for a broad class of models with direct applicability to ATM switches. ¶ We consider a model with A independent ...
Perceptions of waiting time in different service queues
Jones, Peter; Hwang, Jen-Li
2005-01-01
This paper investigates the extent to which there is a gap between customers' perception of waiting time compared with actual waiting times; and whether this gap varies according to service context. It also investigates a new proposition that customers’ perception of time available for the service influences their perception of wait time. A field study collected 455 actual and perceived customer waiting times in a single queue single server system from a retail grocery store, cafeteria, post...
Products of random matrices and queueing system performance evaluation
Krivulin, N. K.
2012-01-01
We consider (max,+)-algebra products of random matrices, which arise from performance evaluation of acyclic fork-join queueing networks. A new algebraic technique to examine properties of the product and investigate its limiting behaviour is proposed based on an extension of the standard matrix (max,+)-algebra by endowing it with the ordinary matrix addition as an external operation. As an application, we derive bounds on the (max,+)-algebra maximal Lyapunov exponent which can be considered a...
Concavity of queueing systems with NBU service times
Rajan, Rajendran; Agrawal, Rajeev
1998-01-01
This paper establishes structural properties for the throughput of a large class of queueing networks with i.i.d. new-better-than-used service times. The main result obtained in this paper is applied to a wide range of networks, including tandems, cycles and fork-join networks with general blocking and starvation (as well as certain networks with splitting and merging of traffic streams), to deduce the concavity of their throughput as a function of system parameters, such as bu...
The queue as a social statement / Maria-Kristiina Soomre
Soomre, Maria-Kristiina, 1978-
2010-01-01
Tallinna Lauluväljakul veebruaris 2010 olnud töötute järjekorrast, kus 5000-st said alternatiivse töö reisisaatjatena 400. Keskerakonna kampaaniatest, mida võib vaadata sotsiaalse kunsti kontekstis. Sügisel 2010 Tallinna Kunstihoone juures korraldatud kunstiprojektist "Art Queue 100x100 EEK", millega sooviti tõmmata tähelepanu kunstiinstitutsioonile. Seoses kunstiga tekkinud järjekordadest, masside valmidusest kampaania korras rünnata kunsti
Gaussian queues in light and heavy-traffic
Debicki, KG; Kosinski, KM Kamil; Mandjes, MRH Michel
2011-01-01
In this paper we investigate Gaussian queues in the light-traffic and in the heavy-traffic regime. The setting considered is that of a centered Gaussian process $X\\equiv\\{X(t):t\\in\\mathbb R\\}$ with stationary increments and variance function $\\sigma^2_X(\\cdot)$, equipped with a deterministic drift $c>0$, reflected at 0: \\[Q_X^{(c)}(t)=\\sup_{-\\infty
Decay of Tails at Equilibrium for FIFO Join the Shortest Queue Networks
Bramson, Maury; Prabhakar, Balaji
2011-01-01
In join the shortest queue networks, incoming jobs are assigned to the shortest queue from among a randomly chosen subset of D queues, in a system of N queues; after completion of service at its queue, a job leaves the network. We also assume that jobs arrive into the system according to a rate-\\alpha N Poisson process, \\alpha 1. We show under the above ansatz that, as N goes to infinity, the tail of the equilibrium queue size exhibits a wide range of behavior depending on the relationship between \\beta and D. In particular, if \\beta > D/(D-1), the tail is doubly exponential and, if \\beta < D/(D-1), the tail has a power law. When \\beta = D/(D-1), the tail is exponentially distributed.
Virtual queueing techniques for UBR+ service in ATM with fair access and minimum bandwidth guarantee
Siu, K.Y.; Wu, Y.; Ren, W.
1998-11-01
The ATM Forum is currently discussing the need for a new best-effort service called UBR+, which is an enhancement to the existing UBR service, to support data traffic. The objective of the UBR+ service is to provide each user with a minimum service rate guarantee and a fair access to any excess available bandwidth. In this paper, the authors present a new efficient scheme for supporting this service. The key advantage of the scheme is that it employs only FIFO queueing (instead of per-VC queueing) and admits simple implementation in ATM switches. The ideas involve a simple scheduling mechanism that is based on per-VC queueing and incorporate the virtual queueing technique that can efficiently emulate per-VC queueing on a shared FIFO queue. Simulation results are presented to show that the schemes can deliver almost ideal performance for supporting the new service requirements of UBR+.
Queueing models for token and slotted ring networks. Thesis
Peden, Jeffery H.
1990-01-01
Currently the end-to-end delay characteristics of very high speed local area networks are not well understood. The transmission speed of computer networks is increasing, and local area networks especially are finding increasing use in real time systems. Ring networks operation is generally well understood for both token rings and slotted rings. There is, however, a severe lack of queueing models for high layer operation. There are several factors which contribute to the processing delay of a packet, as opposed to the transmission delay, e.g., packet priority, its length, the user load, the processor load, the use of priority preemption, the use of preemption at packet reception, the number of processors, the number of protocol processing layers, the speed of each processor, and queue length limitations. Currently existing medium access queueing models are extended by adding modeling techniques which will handle exhaustive limited service both with and without priority traffic, and modeling capabilities are extended into the upper layers of the OSI model. Some of the model are parameterized solution methods, since it is shown that certain models do not exist as parameterized solutions, but rather as solution methods.
Critically loaded queueing models that are throughput suboptimal
Atar, Rami; 10.1214/08-AAP551
2009-01-01
This paper introduces and analyzes the notion of throughput suboptimality for many-server queueing systems in heavy traffic. The queueing model under consideration has multiple customer classes, indexed by a finite set $\\mathcal{I}$, and heterogenous, exponential servers. Servers are dynamically chosen to serve customers, and buffers are available for customers waiting to be served. The arrival rates and the number of servers are scaled up in such a way that the processes representing the number of class-$i$ customers in the system, $i\\in\\mathcal{I}$, fluctuate about a static fluid model, that is assumed to be critically loaded in a standard sense. At the same time, the fluid model is assumed to be throughput suboptimal. Roughly, this means that the servers can be allocated so as to achieve a total processing rate that is greater than the total arrival rate. We show that there exists a dynamic control policy for the queueing model that is efficient in the following strong sense: Under this policy, for every f...
The stationary G/G/s queue with non-identical servers
Pierre Le Gall
1998-01-01
Full Text Available We extend a recently developed factorization method to the case of the G/G/s queue with non-identical servers, by presenting three simple properties which lead to a simple numerical calculation method. We compare our results with those determined by classical Markovian (phase methods in the case of the symmetrical M/G/s queue, and for the mean queueing delay we compare with results given by traffic simulation.
Sojourn time distributions in a Markovian G-queue with batch arrival and batch removal
Yang Woo Shin
1999-01-01
We consider a single server Markovian queue with two types of customers; positive and negative, where positive customers arrive in batches and arrivals of negative customers remove positive customers in batches. Only positive customers form a queue and negative customers just reduce the system congestion by removing positive ones upon their arrivals. We derive the LSTs of sojourn time distributions for a single server Markovian queue with positive customers and negative customers by using the...
On the Fluid Approximation for a Multiclass Queue under Non-Preemptive SBP Service Discipline
Yong Jiang GUO
2012-01-01
A multi-class single server queue under non-preemptive static buffer priority (SBP) service discipline is considered in this paper.Using a bounding technique,we obtain the fluid approximation for the queue length and busy time processes.Furthermore,we prove that the convergence rate of the fluid approximation for the queue length and busy time processes is exponential for large N.Additionally,a sufficient condition for stability is obtained.
On the busy period of discretized GI/GI/infinity queue
The problem of determining the distribution of the busy period, i. e., of the time when at least one customer is served, of the discretized queueing system with infinitely many servers is investigated. Moreover, the idle period and the cycle of a queue are studied. The recurrent formulae are determined and in particular case of a queue with the geometric input the simpler recurrent formulae are given. Those problems arise in the discrete blob length determination in track chambers in high energy physics
刘宴兵; 李秉智
2003-01-01
IP Quality of Service (QoS) guarantee is realized by managing and avoiding congestion in network. In thispaper ,the primary queue algorithms are compared in managing congestion. On the basis of these theories, a newLLQ+CBWFQ algorithm is achieved, and the minimum bandwidth is assigned according to priority or request.
Many-server queues with customer abandonment: Numerical analysis of their diffusion model
Shuangchi He
2013-01-01
Full Text Available We use a multidimensional diffusion process to approximate the dynamics of aqueue served by many parallel servers. Waiting customers in this queue may abandonthe system without service. To analyze the diffusion model, we develop a numericalalgorithm for computing its stationary distribution. A crucial part of the algorithm ischoosing an appropriate reference density. Using a conjecture on the tailbehavior of the limit queue length process, we propose a systematic approach toconstructing a reference density. With the proposed reference density, thealgorithm is shown to converge quickly in numerical experiments. Theseexperiments demonstrate that the diffusion model is a satisfactory approximation formany-server queues, sometimes for queues with as few as twenty servers.
Flow-level convergence and insensitivity for multi-class queueing networks
Neil S. Walton
2012-01-01
Full Text Available We consider a multi-class queueing network as a model of packet transfer in a communication network. We define a second stochastic model as a model of document transfer in a communication network where the documents transferred have a general distribution. We prove the weak convergence of the multi-class queueing process to the document transfer process. Our convergence result allows the comparison of general document size distributions, and consequently, we prove general insensitivity results for the limit queueing process. We discuss how this separation of time-scales method of proving insensitivity may be applied to other insensitive queueing systems.
Multi-class Fork-Join queues & The stochastic knapsack problem
Ding, Sihan
2011-01-01
Multi-class Fork-Join queues are extension of single-class Fork-Join queues. In a multi-class Fork-Join queuing system, different types of jobs arrive, and then split into several sub-jobs. Those sub-jobs go to parallel processing queues. Then, the synchronization is required before the departure of a job. We found very few scientific efforts in analyzing the multi-class Fork-Join queues. In this thesis, we analyzed the expected sojourn time and the expected synchronization time. Since it is ...
Mean sojourn time in two-queue fork-join systems: bounds and approximations
Kemper, B; Mandjes, M.
2011-01-01
This paper considers a fork-join system (or: parallel queue), which is a two-queue network in which any arrival generates jobs at both queues and the jobs synchronize before they leave the system. The focus is on methods to quantify the mean value of the ‘system’s sojourn time’ S: with S i denoting a job’s sojourn time in queue i, S is defined as max{S 1, S 2}. Earlier work has revealed that this class of models is notoriously hard to analyze. In this paper, we focus on the homogeneous case, ...
IAEA activities on nuclear knowledge management
IAEA has obligations and responsibilities in the nuclear area, which require a comprehensive nuclear knowledge potential in different areas which provides for their successful implementation. Nuclear non-proliferation, nuclear safety and security and future nuclear energy development and innovation will need generations of new nuclear professionals with the Knowledge and the Culture of peaceful use of nuclear technology. Nuclear Knowledge Management is part of the mission of IAEA. It has been created to share the knowledge for peaceful uses of nuclear energy. Information collection and dissemination, education, training, sharing of best practices, scientific and technological information management, have always been an element of the Agency's programs. However these were not always highlighted as part of an overall knowledge management agenda. This PowerPoint presentation gives an overview about the nuclear knowledge management activities of the IAEA in 2004 and 2005
Asymptotic inference for waiting times and patiences in queues with abandonment
Gorst-Rasmussen, Anders; Hansen, Martin Bøgsted
Motivated by applications in call center management, we propose a framework based on empirical process techniques for inference about the waiting time and patience distribution in multiserver queues with abandonment. The framework rigorises heuristics based on survival analysis of independent...... and identically distributed observations by allowing correlated successive waiting times. Assuming a regenerative structure of the sequence of offered waiting times, we establish asymptotic properties of estimators of limiting distribution functions and derived functionals. We discuss construction of bootstrap...... confidence intervals and statistical tests, including a simple bootstrap two-sample test for comparing patience distributions. The methods are exemplified in a small simulation study, and a real data example is given involving comparison of patience distributions for two customer classes in a call center....
Management of Logistics Activities and Costing Approaches
İlker KIYMETLİ ŞEN
2014-06-01
Full Text Available In recent years, enterprises are required to reconsider the management of logistics activities as a result of developments such as increasing competition, rapid technological development, and the shortening of product life cycles. As a result of globalization, costs of logistics activities have also increased depending on changes in the quality and quantity of logistics activities. According to research on logistics activities, the physical distribution costs of enterprises may reach up to 30% of sales. For this reason, the management of logistics operations and control of costs caused by these activities is a necessity. The increase in costs negatively impact on the financial performance of enterprises, cash flows, profitability and so value of the shares. The aim of this study was to describe the structure of logistics costs and logistics activities to explain the methods used in costing. For this purpose, many studies in the literature were investigated. The aim of this study was to describe the structure of logistics costs and logistics activities to explain the methods used in costing. For this purpose, many studies in the literature were investigated.
Stochastic network optimization with application to communication and queueing systems
Neely, Michael
2010-01-01
This text presents a modern theory of analysis, control, and optimization for dynamic networks. Mathematical techniques of Lyapunov drift and Lyapunov optimization are developed and shown to enable constrained optimization of time averages in general stochastic systems. The focus is on communication and queueing systems, including wireless networks with time-varying channels, mobility, and randomly arriving traffic. A simple drift-plus-penalty framework is used to optimize time averages such as throughput, throughput-utility, power, and distortion. Explicit performance-delay tradeoffs are prov
The Robo-AO automated intelligent queue system
Riddle, Reed L; Papadopoulos, Athanasios; Baranec, Christoph; Law, Nicholas M
2014-01-01
Robo-AO is the first automated laser adaptive optics instrument. In just its second year of scientific operations, it has completed the largest adaptive optics surveys to date, each comprising thousands of targets. Robo-AO uses a fully automated queue scheduling system that selects targets based on criteria entered on a per observing program or per target basis, and includes the ability to coordinate with US Strategic Command automatically to avoid lasing space assets. This enables Robo-AO to select among thousands of targets at a time, and achieve an average observation rate of approximately 20 targets per hour.
Integrated service resource reservation using queueing networks theory
Brewka, Lukasz Jerzy; Iversen, Villy Bæk; Kardaras, Georgios
2014-01-01
This study analyses multi-server multi-service queueing networks with service protection. To guarantee each service a certain quality-of-service and at the same time ensure high utilisation of servers, a minimum capacity is reserved each service. In addition, all services share the remaining non......-reserved capacity and all buffers in such a way that the system becomes reversible. This implies the model has product form between nodes and is insensitive to the packet size distribution. An analytical model and algorithm for performance evaluation are presented....
Max-plus algebra models of queueing networks
Krivulin, Nikolai K.
2012-01-01
A class of queueing networks which may have an arbitrary topology, and consist of single-server fork-join nodes with both infinite and finite buffers is examined to derive a representation of the network dynamics in terms of max-plus algebra. For the networks, we present a common dynamic state equation which relates the departure epochs of customers from the network nodes in an explicit vector form determined by a state transition matrix. It is shown how the matrices inherent in particular ne...
Light Traffic Equivalence in Single-Server Queues
Asmussen, Soren
1992-01-01
A light traffic limit theorem is proved for random walks in a triangular array setting similar to the heavy traffic situation, the basic assumption being on the moments in the right tail of the increment distribution. When specialized to GI/G/1 queues, this result is shown to contain the known types of light traffic behaviour in this setting (Daley and Rolski) as well as some additional ones. Intuitively, the results state that typically delay in light traffic occurs with just one customer in...
Rainfall time series synthesis from queue scheduling of rain event fractals over radio links
Alonge, Akintunde A.; Afullo, Thomas J.
2015-12-01
Rainfall attenuation over wireless networks stems from random fluctuations in the natural process of arriving rainfall rates over radio links. This arrival process results in discernible rainfall traffic pattern which manifests as naturally scheduled and queue-generated rain spikes. Hence, the phenomenon of rainfall process can be approached as a semi-Markovian queueing process, with event characteristics dependent on queue parameters. However, a constraint to this approach is the knowledge of the physical characteristics of queue-generated rain spikes. Therefore, this paper explores the probability theory and descriptive mathematics of rain spikes in rainfall processes. This investigation presents the synthesis of rainfall queue with rain spikes at subtropical and equatorial locations of Durban (29°52'S, 30°58'E) and Butare (2°36'S, 29°44'E), respectively. The resulting comparative analysis of rainfall distributions, using error analysis at both locations, reveals that queue-generated rainfall compares well with measured rainfall data set. This suggests that the time-varying process of rainfall, though stochastic, can be synthesized via queue scheduling with the application of relevant queue parameters at any location.
Exponential and Strong Ergodicity for Markov Processes with an Application to Queues
Yuanyuan LIU; Zhenting HOU
2008-01-01
For an ergodic continuous-time Markov process with a particular state in its space, the authors provide the necessary and sufficient conditions for exponential and strongerg odicity in terms of the moments of the first hitting time on the state. An application to the queue length process of M/G/1 queue with multiple vacations is given.
Managing CSCL Activity through networking models
Luis Casillas
2014-04-01
Full Text Available This study aims at managing activity carried out in Computer-Supported Collaborative Learning (CSCL environments. We apply an approach that gathers and manages the knowledge underlying huge data structures, resulting from collaborative interaction among participants and stored as activity logs. Our method comprises a variety of important issues and aspects, such as: deep understanding of collaboration among participants in workgroups, definition of an ontology for providing meaning to isolated data manifestations, discovering of knowledge structures built in huge amounts of data stored in log files, and development of high-semantic indicators to describe diverse primitive collaborative acts, and binding these indicators to formal descriptions defined in the collaboration ontology; besides our method includes gathering collaboration indicators from web forums using natural language processing (NLP techniques.
Request queues for interactive clients in a shared file system of a parallel computing system
Bent, John M.; Faibish, Sorin
2015-08-18
Interactive requests are processed from users of log-in nodes. A metadata server node is provided for use in a file system shared by one or more interactive nodes and one or more batch nodes. The interactive nodes comprise interactive clients to execute interactive tasks and the batch nodes execute batch jobs for one or more batch clients. The metadata server node comprises a virtual machine monitor; an interactive client proxy to store metadata requests from the interactive clients in an interactive client queue; a batch client proxy to store metadata requests from the batch clients in a batch client queue; and a metadata server to store the metadata requests from the interactive client queue and the batch client queue in a metadata queue based on an allocation of resources by the virtual machine monitor. The metadata requests can be prioritized, for example, based on one or more of a predefined policy and predefined rules.
Cycle-by-Cycle Queue Length Estimation for Signalized Intersections Using Multi-Source Data
Zhongyu Wang; Qing Cai; Bing Wu; Yinhai Wang; Linbo Li
2015-01-01
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 to an infinite Server Queue with Varying Arrival and Departure Rate
A. A. El-Sherbiny
2010-01-01
Full Text Available Problem statement: In many potential application of queueing theory, the transient solution of queueing system is important. Approach: This study presented the transient solution for infinite server queues with Poisson arrivals and exponential service times when the parameters of both distributions are allowed to vary with time. Based on generating functions technique which results in a simple differential equation. Using the properties of Bessel functions in the solution of this differential equation, the solution of an infinite server queues can be given in simple form. Results: The researcher obtained the transient solution an infinite server queues with Poisson arrivals and exponential service times when the parameters of both distributions are allowed to vary with time and prove that some past results are special case from his results. Conclusion: These results indicated that the probabilities can be extracted in a direct way.
Queueing-Based Synchronization and Entrainment for Synthetic Gene Oscillators
Mather, William; Butzin, Nicholas; Hochendoner, Philip; Ogle, Curtis
Synthetic gene oscillators have been a major focus of synthetic biology research since the beginning of the field 15 years ago. They have proven to be useful both for biotechnological applications as well as a testing ground to significantly develop our understanding of the design principles behind synthetic and native gene oscillators. In particular, the principles governing synchronization and entrainment of biological oscillators have been explored using a synthetic biology approach. Our work combines experimental and theoretical approaches to specifically investigate how a bottleneck for protein degradation, which is present in most if not all existing synthetic oscillators, can be leveraged to robustly synchronize and entrain biological oscillators. We use both the terminology and mathematical tools of queueing theory to intuitively explain the role of this bottleneck in both synchronization and entrainment, which extends prior work demonstrating the usefulness of queueing theory in synthetic and native gene circuits. We conclude with an investigation of how synchronization and entrainment may be sensitive to the presence of multiple proteolytic pathways in a cell that couple weakly through crosstalk. This work was supported by NSF Grant #1330180.
Heavy traffic analysis for EDF queues with reneging
Kruk, Łukasz; Ramanan, Kavita; Shreve, Steven; 10.1214/10-AAP681
2011-01-01
This paper presents a heavy-traffic analysis of the behavior of a single-server queue under an Earliest-Deadline-First (EDF) scheduling policy in which customers have deadlines and are served only until their deadlines elapse. The performance of the system is measured by the fraction of reneged work (the residual work lost due to elapsed deadlines) which is shown to be minimized by the EDF policy. The evolution of the lead time distribution of customers in queue is described by a measure-valued process. The heavy traffic limit of this (properly scaled) process is shown to be a deterministic function of the limit of the scaled workload process which, in turn, is identified to be a doubly reflected Brownian motion. This paper complements previous work by Doytchinov, Lehoczky and Shreve on the EDF discipline in which customers are served to completion even after their deadlines elapse. The fraction of reneged work in a heavily loaded system and the fraction of late work in the corresponding system without renegi...
A Queueing-Based Approach to Overload Detection
Mandjes, Michel; Żuraniewski, Piotr
The control of communication networks critically relies on procedures capable of detecting unanticipated load changes. In this paper we develop such techniques, in a setting in which each connection consumes roughly the same amount of bandwidth (with VoIP as a leading example). For the situation of exponential holding times an explicit analysis can be performed in a large-deviations regime, leading to approximations of the test statistic of interest (and, in addition, to results for the transient of the M/M/∞ queue, which are of independent interest). This procedure being applicable to exponential holding times only, and also being numerically rather involved, we then develop an approximate procedure for general holding times. In this procedure we record the number of trunks occupied at equidistant points in time {Δ},2{Δ},ldots, where {Δ} is chosen sufficiently large to safely assume that the samples are independent; this procedure is backed by results on the transient of the M/G/∞ queue. The validity of the testing procedures is demonstrated through an extensive set of numerical experiments.
Upper Bound for Queue length in Regulated Burst Service Scheduling
Mahmood Daneshvar Farzanegan
2016-01-01
Full Text Available Quality of Service (QoS provisioning is very important in next computer/communication networks because of increasing multimedia services. Hence, very investigations are performed in this area. Scheduling algorithms effect QoS provisioning. Lately, a scheduling algorithm called Regulated Burst Service Scheduling (RBSS suggested by author in [1] to provide a better service to bursty and delay sensitive services such as video. One of the most significant feature in RBSS is considering burstiness of arrival traffic in scheduling algorithm. In this paper, an upper bound of queue length or buffer size and service curve are calculated by Network Calculus analysis for RBSS. Because in RBSS queue length is a parameter that is considered in scheduling arbitrator, analysis results a differential inequality to obtain service curve. To simplify, arrival traffic is assumed to be linear that is defined in the paper clearly. This paper help to analysis delay in RBSS for different traffic with different specifications. Therefore, QoS provisioning will be evaluated.
Applications of queueing theory to stochastic models of gene expression
Kulkarni, Rahul
2012-02-01
The intrinsic stochasticity of cellular processes implies that analysis of fluctuations (`noise') is often essential for quantitative modeling of gene expression. Recent single-cell experiments have carried out such analysis to characterize moments and entire probability distributions for quantities of interest, e.g. mRNA and protein levels across a population of cells. Correspondingly, there is a need to develop general analytical tools for modeling and interpretation of data obtained from such single-cell experiments. One such approach involves the mapping between models of stochastic gene expression and systems analyzed in queueing theory. The talk will provide an overview of this approach and discuss how theorems from queueing theory (e.g. Little's Law) can be used to derive exact results for general stochastic models of gene expression. In the limit that gene expression occurs in bursts, analytical results can be obtained which provide insight into the effects of different regulatory mechanisms on the noise in protein steady-state distributions. In particular, the approach can be used to analyze the effect of post-transcriptional regulation by non-coding RNAs leading to new insights and experimentally testable predictions.
Design professional activity analysis in design management
Claudia de Souza Libanio
2013-08-01
Full Text Available Design use perception, as an essential element for achieving competitive advantage, also suggests the need to manage the design activities in companies. However, a few is discussed about the activity of these design professionals who participate in this process, their roles, functions and competencies, including their connections to a company and other involved sectors. This article aims to analyze, during the design management processes, the work relations of design professionals connected to organizations both internal and externally, in order to comprehend the structure and intervenient factors on the activity of these professionals, as well as the interactions with their main coworkers. The methodology was exploratory and qualitative, using in-depth interviews with three design professionals. Subsequently, the responses were analyzed allowing the comparison of these obtained data to the theoretical bases researched. Through this case study, it was possible to realize the aspects and the structure of the design professional activity, connected intern and externally to organizations, as well as its relations with the main coworkers.
Basic components of construction enterprises’ management marketing activities system
Seleznova Olha Olexandrivna
2015-01-01
This article investigated the basic components of construction enterprises’ management marketing activities system. It is developed the model of the construction enterprises’ management marketing activities system. The article explores the essence of the stages of forming the construction enterprises’ management marketing activities system. The article reveals the basic elements of marketing management – mission, goals, strategy. It describes the basic functions of marketing management system...
Design for manufacturability production management activity report
Miyazaki, Norihiko; Sato, T.; Honma, M.; Yoshioka, N.; Hosono, K.; Onodera, T.; Itoh, H.; Suzuki, H.; Uga, T.; Kadota, K.; Iriki, N.
2006-05-01
Design For Manufacturability Production Management (DFM-PM) Subcommittee has been started in succession to Reticle Management Subcommittee (RMS) in Semiconductor Manufacturing Technology Committee for Japan (SMTCJ) from 2005. Our activity focuses on the SoC (System On Chip) Business, and it pursues the improvement of communication in manufacturing technique. The first theme of activity is the investigation and examination of the new trends about production (manufacturer) technology and related information, and proposals of business solution. The second theme is the standardization activity about manufacture technology and the cooperation with related semiconductors' organizations. And the third theme is holding workshop and support for promotion and spread of the standardization technology throughout semiconductor companies. We expand a range of scope from design technology to wafer pattern reliability and we will propose the competition domain, the collaboration area and the standardization technology on DFM. Furthermore, we will be able to make up a SoC business model as the 45nm node technology beyond manufacturing platform in cooperating with the design information and the production information by utilizing EDA technology.
Jonatha Anselmi
2015-12-01
Full Text Available We consider a queueing system composed of a dispatcher that routes jobs to a set of non-observable queues working in parallel. In this setting, the fundamental problem is which policy should the dispatcher implement to minimize the stationary mean waiting time of the incoming jobs. We present a structural property that holds in the classic scaling of the system where the network demand (arrival rate of jobs grows proportionally with the number of queues. Assuming that each queue of type r is replicated k times, we consider a set of policies that are periodic with period k∑rpr and such that exactly pr jobs are sent in a period to each queue of type r. When k→∞, our main result shows that all the policies in this set are equivalent, in the sense that they yield the same mean stationary waiting time, and optimal, in the sense that no other policy having the same aggregate arrival rate to all queues of a given type can do better in minimizing the stationary mean waiting time. This property holds in a strong probabilistic sense. Furthermore, the limiting mean waiting time achieved by our policies is a convex function of the arrival rate in each queue, which facilitates the development of a further optimization aimed at solving the fundamental problem above for large systems.
Alonge, Akintunde A.; Afullo, Thomas J.
2014-08-01
Attenuation due to precipitation remains an important design factor in the future deployment of terrestrial and earth-space communication radio links. Largely, there are concerted efforts to understand the dynamics of precipitation in attenuation occurrence at subtropical, tropical, and equatorial region of Africa. In this deliberate approach, rainfall spikes pertaining to rain cells are conceptualized as distinct rain spike traffic over radio links, by applying queueing theory concepts. The queue distributions at Durban (29°52'S, 30°58'E) and Butare (2°36'S, 29°44'E)—respectively, of subtropical and equatorial climates—are investigated from distrometer measurements. The data sets at both sites are observed over four rain regimes: drizzle, widespread, shower, and thunderstorm. The queue parameters of service time and inter-arrival of rain spikes traffic at both regions are found to be Erlang-k distributed (Ek) and exponentially distributed (M), respectively. It is established that the appearance of rain rates over radio links invariably follows a First Come, First Served (FCFS), multi-server (s), infinite queue, and semi-Markovian process, designated as M/Ek/s/∞/FCFS discipline. Modeled queue parameters at both regions are found to vary significantly over different regimes. However, these queue parameters over the entire data set suggest similar queue patterns at both sites. More importantly, power law relationships describing other queue-related parameters are formulated. The paper concludes by demonstrating an application of queueing theory for rainfall synthesis. The proposed technique will provide an alternative method of estimating rain cell sizes and rain attenuation over satellite and terrestrial links.
COMSY software assists lifetime management activities
The COMSY program has been developed to provide an effective software tool for the plant life management of systems and mechanical components. The program utilizes more than 25 years of experience resulting from research activities and operational experiences. It is designed to support a plant-wide strategy providing lifetime predictions for mechanical elements, which are validated by a small number of examinations at priority locations. The objective is to establish economically optimized inspection and maintenance programs, while maintaining high levels of plant safety and availability. This is accomplished by focusing inspection activities on the actually degradation relevant locations based on reliable service life predictions. This capability is particularly useful for the service life extension of systems and components. Within the last years the program has been successfully applied to various nuclear power plants and the benefit of this software-based strategy could be confirmed by field experience. (author)
On the M/G/1 queueing system with multiclass customers and fixed feedback
ZHANG Qi-zhi
2008-01-01
The M/G/1 queueing system with multiclass customer arrivals, fixed feedback, and first come first served policy is considered, where different classes of customers have different arrival rates, service-time distributions, and feedback numbers. The joint probability generation function of queue size of each class and the Laplace-Stieltjes transform of the total sojourn time of a customer in each class are presented, which extended the results obtained by Choi B D. The mean queue size of each class and mean total sojourn time of a customer in each class are obtained with this result. The results can be used in computer and communication networks for their performance analysis.
Film traffic queueing model for the DUMC radiology department
This paper discusses the radiology department traffic model for Duke University Medical Center (DUMC) which simulates the flow of film through the department, and then incorporates the effect of introducing a PACS-type system into present operations. Each Radiology Section is considered separately for queuing of two types of film: old film (from previous exams) and new film (from the present exam). The amount of film in each queue at any time is controlled by controlling hours of operation, service times, delay, and arrival rates. The model also takes into account the use of film in each major radiology area. This gives some idea of the load on a device in that area as well as the amount of storage needed to adequately handle its daily load is local storage at the display device is desired
Asymptotic expansions for large closed and loss queueing networks
Yaakov Kogan
2002-01-01
Full Text Available Loss and closed queueing network models have long been of interest to telephone and computer engineers and becoming increasingly important as models of data transmission networks. This paper describes a uniform approach that has been developed during the last decade for asymptotic analysis of large capacity networks with product form of the stationary probability distribution. Such a distribution has an explicit form up to the normalization constant, or the partition function. The approach is based on representing the partition function as a contour integral in complex space and evaluating the integral using the saddle point method and theory of residues. This paper provides an introduction to the area and a review of recent work.
A-MMLQ Algorithm for Multi-level Queue Scheduling
Manupriya Hasija
2013-07-01
Full Text Available This being the era of advancement in computing domain, the emphasis is on better resource scheduling. Scheduling is not confined to dealing multiple tasks by a single processor. It’s a dawn with multiprocessing and multitasking. Although multiprocessor systems impose several overheads but still make the concept amazingly interesting. The scheduling field has taken a whirlwind after the notion of multiprocessing. Many of the uniprocessor algorithms do fit well under the multiprocessor systems but, still necessitating a further development aiming solely on multiprocessor scheduling. This paper thus sketches a new idea to modify and extend the well-known multi-level queue scheduling, taking into account the arrival time/ arrival sequence to conceptualize an innovative scheduling algorithm.
Stochastic queueing-theory approach to human dynamics
Walraevens, Joris; Demoor, Thomas; Maertens, Tom; Bruneel, Herwig
2012-02-01
Recently, numerous studies have shown that human dynamics cannot be described accurately by exponential laws. For instance, Barabási [Nature (London)NATUAS0028-083610.1038/nature03459 435, 207 (2005)] demonstrates that waiting times of tasks to be performed by a human are more suitably modeled by power laws. He presumes that these power laws are caused by a priority selection mechanism among the tasks. Priority models are well-developed in queueing theory (e.g., for telecommunication applications), and this paper demonstrates the (quasi-)immediate applicability of such a stochastic priority model to human dynamics. By calculating generating functions and by studying them in their dominant singularity, we prove that nonexponential tails result naturally. Contrary to popular belief, however, these are not necessarily triggered by the priority selection mechanism.
Classroom Management to Support Active Middle Level Classrooms
Bryan Lloyd McCoy
2012-01-01
This article presents a discussion of connections between middle level concepts of teaching and learning and managing a classroom through creating opportunities for active and engaged learning. The article argues and concludes that classroom management is more about managing learning than managing behavior and that one effective way to manage student behavior is to create an environment where students continuously engage in active learning (Haydon, Borders, Embury, & Clarke, ...
Classroom Management to Support Active Middle Level Classrooms
Bryan Lloyd McCoy
2012-09-01
Full Text Available
This article presents a discussion of connections between middle level concepts of teaching and learning and managing a classroom through creating opportunities for active and engaged learning. The article argues and concludes that classroom management is more about managing learning than managing behavior and that one effective way to manage student behavior is to create an environment where students continuously engage in active learning (Haydon, Borders, Embury, & Clarke, 2009.
Classroom Management to Support Active Middle Level Classrooms
Bryan Lloyd McCoy
2012-09-01
Full Text Available This article presents a discussion of connections between middle level concepts of teaching and learning and managing a classroom through creating opportunities for active and engaged learning. The article argues and concludes that classroom management is more about managing learning than managing behavior and that one effective way to manage student behavior is to create an environment where students continuously engage in active learning (Haydon, Borders, Embury, & Clarke, 2009.
Dorota Kuchta; Radoslaw Rynca
2006-01-01
The paper presents a proposal of the Activity Balance Scorecard (ABSC). It is a combination of Activity Based Costing and a modification of Activity Based Management. Contrary to the traditional cascading of the Balanced Scorecard to organisational structures, ABSC is constructed directly for activities or tasks. These activities or tasks should be selected on the basis of ABC results – as it is them which give the information the share of which tasks in the cost structure is high. The ABSC w...