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...
Single server bulk queue with service interruption, two phase repairs and state dependent rates
This paper reports a study on a single server queue with bulk arrival and bulk service patterns where in the incoming traffic depends on the state of the server which may be in operating or breakdown state. The repair of the breakdown server is performed in two phases. The operating duration of server, repair duration of both phases of repairing as well as job's inter-arrival times and service times are exponentially distributed. By using generating function approach, the transient analysis for the queue size distribution has been carried out. For steady state, the stability condition and average queue length for various states have been derived. By taking a numerical illustration, the effect of various parameters on the average queue length has been depicted graphically
Information Theory vs. Queueing Theory for Resource Allocation in Multiple Access Channels
ParandehGheibi, Ali; Ozdaglar, Asuman; Eryilmaz, Atilla
2008-01-01
We consider the problem of rate allocation in a fading Gaussian multiple-access channel with fixed transmission powers. The goal is to maximize a general concave utility function of the expected achieved rates of the users. There are different approaches to this problem in the literature. From an information theoretic point of view, rates are allocated only by using the channel state information. The queueing theory approach utilizes the global queue-length information for rate allocation to guarantee throughput optimality as well as maximizing a utility function of the rates. In this work, we make a connection between these two approaches by showing that the information theoretic capacity region of a multiple-access channel and its stability region are equivalent. Moreover, our numerical results show that a simple greedy policy which does not use the queue-length information can outperform queue-length based policies in terms of convergence rate and fairness.
Methods for estimating vehicle queues at a marine terminal: A computational comparison
Chen Gang
2014-09-01
Full Text Available A long queue of vehicles at the gate of a marine terminal is a common traffic phenomenon in a port-city, which sometimes causes problems in urban traffic. In order to be able to solve this issue, we firstly need accurate models to estimate such a vehicle queue length. In this paper, we compare the existing methods in a case study, and evaluate their advantages and disadvantages. Particularly, we develop a simulation-based regression model, using the micro traffic simulation software PARAMIC. In simulation, it is found that the queue transient process follows a natural logarithm curve. Then, based on these curves, we develop a queue length estimation model. In the numerical experiment, the proposed model exhibits better estimation accuracy than the other existing methods
Kempa, Wojciech M.
2015-11-01
A finite-buffer GI/M/1/N-type queueing model with single working vacations is considered. Every time when the system becomes empty the server initializes an exponentially distributed single working vacation period, during which the processing of jobs is carried out with another (slower) rate. After finishing the vacation period the service process is being continued with normal (higher) speed. The next working vacation period is started at the next moment at which the queue empties and so on. The systems of integral equations for time-dependent queueing delay distributions, conditioned by the initial level of buffer saturation and related to each other, are built for systems beginning the operation in normal and working vacation modes, separately. The solutions for corresponding systems written for Laplace transforms are given explicitly using the linear algebraic approach.
Approximations in the performance evaluation of queueing systems. Final technical report
Knessl, Charles; Tier, Charles
2001-06-06
The research program on this grant was to develop new asymptotic and perturbation methods for approximating the performance of queueing systems. This involved obtaining approximations to complicated equations.The approximations provide accurate formulas for the performance measures. Queueing models of these types arise in the analysis of computer and communications systems such as ATM networks. In addition, the methods developed in the proposal were also found to be applicable to other stochastic and diffusion models.
Optimization of a Call Centre Performance Using the Stochastic Queueing Models
Brezavšček Alenka; Baggia Alenka
2014-01-01
Background: A call centre usually represents the first contact of a customer with a given company. Therefore, the quality of its service is of key importance. An essential factor of the call centre optimization is the determination of the proper number of operators considering the selected performance measure. Results of previous research show that this can be done using the queueing theory approach. Objectives: The paper presents the practical application of the stochastic queueing models ai...
Optimization of a forest harvesting set based on the Queueing Theory: Case study from Karelia
Shegelman Ilya; Budnik Pavel; Morozov Evsey
2015-01-01
The modern technological process of timber harvesting is a complex system both technically and organizationally. Nowadays, the study of such systems and improvement of their efficiency is impossible without the use of mathematical modeling methods. The paper presents the methodology for the optimization of logging operations based on the queueing theory. We show the adapted queueing model, which characterizes the process of logging with the use of a harvesting set consisting of harvesters and...
Kramer, Glen; A. Banerjee; Singhal, N K; Mukherjee, B.; Dixit, S.; Ye, Y H
2004-01-01
In this paper, we propose and investigate the characteristics of a fair queueing with service envelopes (FQSE) algorithm-a hierarchical fair-share scheduling algorithm for access networks based on a remote scheduling system such as Ethernet passive optical networks (EPON) or cable TV network. FQSE is designed to overcome the limiting factors of a typical remote scheduling system such as large control-plane delay, limited control-plane bandwidth, and significant queue switch-over overhead. The...
Discrete Time Analysis of Multi-Server Queueing Systems in Material Handling and Service
Matzka, Judith M.
2011-01-01
In this doctoral thesis, performance parameters of multi-server queueing systems are estimated under general stochastic assumptions. We present an exact calculation method for the discrete time distribution of the number of customers in the queueing system at the arrival moment of an arbitrary customer. The waiting time distribution and the sojourn time distribution are estimated exactly, as well. For the calculation of the inter departure time distribution, we present an approximation method.
Flow-level convergence and insensitivity for multi-class queueing networks
Neil S. Walton
2012-01-01
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 result...
Random Linear Network Coding for Time-Division Duplexing: Queueing Analysis
Lucani, Daniel E.; Médard, Muriel; Stojanovic, Milica
2009-01-01
We study the performance of random linear network coding for time division duplexing channels with Poisson arrivals. We model the system as a bulk-service queue with variable bulk size. A full characterization for random linear network coding is provided for time division duplexing channels [1] by means of the moment generating function. We present numerical results for the mean number of packets in the queue and consider the effect of the range of allowable bulk sizes. We show that there exi...
Heavy-traffic limits for a many-server queueing network with switchover
Pang, Guodong; Yao, David D.
2013-01-01
We study a multiclass Markovian queueing network with switchover across a set of many-server stations. New arrivals to each station follow a nonstationary Poisson process. Each job waiting in queue may, after some exponentially distributed patience time, switch over to another station or leave the network following a probabilistic and state-dependent mechanism. We analyze the performance of such networks under the many-server heavy-traffic limiting regimes, including the ...
AVAILABILITY ANALYSIS OF THE QUEUEING SYSTEM GI/PH/1 WITH SERVER BREAKDOWNS
YUAN Xueming; LI Wei
2003-01-01
In the existing literature of Repairable Queueing Systems (RQS), i.e., queueing systems with server breakdowns, it is almost all assumed that interarrival times of successive customers are independent, identically exponentially distributed. In this paper, we deal with more generic system GI/PH/1 with server's exponential uptime and phase-type repair time. With matrix analysis theory, we establish the equilibrium condition and the characteristics of the system, derive the transient and stationary availability behavior of the system.
Managing Siting Activities for Nuclear Power Plants
One of the IAEA's statutory objectives is to ''seek to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world''. One way this objective is achieved is through the publication of a range of technical series. Two of these are the IAEA Nuclear Energy Series and the IAEA Safety Standards Series. According to Article III.A.6 of the IAEA Statute, the safety standards establish 'standards of safety for protection of health and minimization of danger to life and property.' The safety standards include the Safety Fundamentals, Safety Requirements and Safety Guides. These standards are written primarily in a regulatory style, and are binding on the IAEA for its own programmes. The principal users are the regulatory bodies in Member States and other national authorities. The IAEA Nuclear Energy Series comprises reports designed to encourage and assist R and D on, and application of, nuclear energy for peaceful uses. This includes practical examples to be used by owners and operators of utilities in Member States, implementing organizations, academia, and government officials, among others. This information is presented in guides, reports on technology status and advances, and best practices for peaceful uses of nuclear energy based on inputs from international experts. The IAEA Nuclear Energy Series complements the IAEA Safety Standards Series. The introduction of nuclear power brings new challenges to States - one of them being the selection of appropriates sites. It is a project that needs to begin early, be well managed, and deploy good communications with all stakeholders; including regulators. This is important, not just for those States introducing nuclear power for the first time, but for any State looking to build a new nuclear power plant. The purpose of the siting activities goes beyond choosing a suitable site and acquiring a licence. A large part of the project is about producing and maintaining a validated
Radio Active Waste Management: Underground Repository Method
Finding a solution for nuclear waste is a key issue, not only for the protection of the environment but also for the future of the nuclear industry. Ten years from now, when the first decisions for the replacement of existing nuclear power plants will have to be made, The general public will require to know the solution for nuclear waste before accepting new nuclear plants. In other words, an acceptable solution for the management of nuclear waste is a prerequisite for a renewal of nuclear power. Most existing wastes are being stored in safe conditions waiting for permanent solution, with some exceptions in the former Eastern Bloc. Temporary surface or shallow storage is a well known technique widely used all over the world. A significant research effort has been made by the author of this paper in the direction of underground repository. The underground repository appears to be a good solution. Trying to transform dangerous long lived radionuclides into less harmful short lived or stable elements is a logical idea. It is indeed possible to incinerate or transmute heavy atoms of long lived elements in fast breeder reactors or even in pressurised or boiling water reactors. There are also new types of reactors which could be used, namely accelerator driven systems. High level and long lived wastes (spent fuel and vitrified waste) contain a mixture of high activity (heat producing) short lived nuclides and low activity long lived alpha emitting nuclides. To avoid any alteration due to temperature of the engineered or geological barrier surrounding the waste underground, it is necessary to store the packages on the surface for several decades (50 years or more) to allow a sufficient temperature decrease before disposing of them underground. In all cases, surface (or shallow) storage is needed as a temporary solution. This paper gives a detailed and comprehensive view of the Deep Geological Repository, providing a pragmatic picture of the means to make this method, a
A queueing theory based model for business continuity in hospitals.
Miniati, R; Cecconi, G; Dori, F; Frosini, F; Iadanza, E; Biffi Gentili, G; Niccolini, F; Gusinu, R
2013-01-01
Clinical activities can be seen as results of precise and defined events' succession where every single phase is characterized by a waiting time which includes working duration and possible delay. Technology makes part of this process. For a proper business continuity management, planning the minimum number of devices according to the working load only is not enough. A risk analysis on the whole process should be carried out in order to define which interventions and extra purchase have to be made. Markov models and reliability engineering approaches can be used for evaluating the possible interventions and to protect the whole system from technology failures. The following paper reports a case study on the application of the proposed integrated model, including risk analysis approach and queuing theory model, for defining the proper number of device which are essential to guarantee medical activity and comply the business continuity management requirements in hospitals. PMID:24109839
Analysis of DAR(1)/D/s Queue with Quasi-Negative Binomial-II as Marginal Distribution
Kanichukattu Korakutty Jose; Bindu Abraham
2011-01-01
In this paper we consider the arrival process of a multiserver queue governed by a discrete autoregressive process of order 1 [DAR(1)] with Quasi-Negative Binomial Distribution-II as the marginal distribution. This discrete time multiserver queueing system with autoregressive arrivals is more suitable for modeling the Asynchronous Transfer Mode(ATM) multiplexer queue with Variable Bit Rate (VBR) coded teleconference traffic. DAR(1) is described by a few parameters and it is easy to match the ...
The Management System for Facilities and Activities. Safety Requirements
This publication establishes requirements for management systems that integrate safety, health, security, quality assurance and environmental objectives. A successful management system ensures that nuclear safety matters are not dealt with in isolation but are considered within the context of all these objectives. The aim of this publication is to assist Member States in establishing and implementing effective management systems that integrate all aspects of managing nuclear facilities and activities in a coherent manner. It details the planned and systematic actions necessary to provide adequate confidence that all these requirements are satisfied. Contents: 1. Introduction; 2. Management system; 3. Management responsibility; 4. Resource management; 5. Process implementation; 6. Measurement, assessment and improvement.
Girvan, James T.; Harris, Frances
A survey completed by managers of 77 senior centers in Idaho revealed that meals, blood pressure screening, and games and trips were the most successful activities offered. Alzheimer's support groups, library books for loan, and exercise classes were the least successful. Possible reasons for the success or failure of these activities were…
A bulk queueing system under N-policy with bilevel service delay discipline and start-up time
David C. R. Muh
1993-01-01
Full Text Available The author studies the queueing process in a single-server, bulk arrival and batch service queueing system with a compound Poisson input, bilevel service delay discipline, start-up time, and a fixed accumulation level with control operating policy. It is assumed that when the queue length falls below a predefined level r(≥1, the system, with server capacity R, immediately stops service until the queue length reaches or exceeds the second predefined accumulation level N(≥r. Two cases, with N≤R and N≥R, are studied.
On the Discrete-Time GeoX/G/1 Queues under N-Policy with Single and Multiple Vacations
Sung J. Kim
2013-01-01
Full Text Available We consider the discrete-time GeoX/G/1 queue under N-policy with single and multiple vacations. In this queueing system, the server takes multiple vacations and a single vacation whenever the system becomes empty and begins to serve customers only if the queue length is at least a predetermined threshold value N. Using the well-known property of stochastic decomposition, we derive the stationary queue-length distributions for both vacation models in a simple and unified manner. In addition, we derive their busy as well as idle-period distributions. Some classical vacation models are considered as special cases.
DESAIN FRAMEWORK MULTIMEDIA QUEUEING SYSTEM BERBASIS ANDROID ANTRIAN PASIEN PUSKESMAS
Erika Devi Udayanti
2015-10-01
Full Text Available Saat ini antrian di puskesmas masih dilakukan dengan metode konvensional, yaitu dengan menumpuk kartu registrasi. Metode seperti ini memungkinkan kartu menjadi terselip. Selain itu, penumpukan kartu yang tidak benar dapat mengakibatkan urutan menjadi tidak sesuai dengan urutan yang seharusnya. Pasien yang datang lebih ahir dimungkinkan untuk dapat dilayani lebih awal dari pasien yang sudah lama menunggu. Penelitian ini mengusulkan multimedia queueing system berbasis android untuk layanan antrian pasien puskesmas. Sistem ini mencatat antrian di dalam database server, sehingga tidak ada kartu yang terselip ataupun salah tumpuk. Lebih lanjut lagi, penelitian ini akan mengangkat kecanggihan mesin android sebagai input device. Sedangkan untuk output devicenya, menggunakan portable bluetooth printer dan layar LCD. Setiap pasien yang datang dapat mencetak tiket antrian dengan menyentuh tombol pada layar mesin android. Mesin android tersebut kemudian akan mencetak tiket melaui printer portable yang disediakan dan mengirim nomor antrian ke database server. Selain itu, mesin android ini juga memotret wajah pasien yang masuk, dan file foto akan dikirim beserta nomor antrian ke server. Pada saat giliran pasien tiba, layar LCD akan menampilkan nomor antrian pasien beserta fotonya. Metode ini diharapkan mampu menyelesaikan problem kartu registrasi terselip, dan juga membantu pasien yang buta huruf/angka. Kata Kunci: puskesmas, sistem antrian, android
Weighted fair queueing scheduling for World Wide Web proxy servers
El Abdouni Khayari, Rachid; Sadre, Ramin; Haverkort, Boudewijn R.; Zoschke, Norman
2002-07-01
Current world-wide web servers as well as proxy servers rely for their scheduling on services provided by the underlying operating system. In practice, this means that some form of first-come-first-served (FCFS) scheduling is utilised. Although FCFS is a reasonable scheduling strategy for job sequences that do not show much variance, in the world-wide web (WWW), however, it has been shown that the typical object sizes requested do exhibit heavy tails. This means that the probability to observe very long jobs (very large objects) is much higher than typically predicted using an exponential model. Under these circumstances, job scheduling on the basis of shortest-job first (SJF) has been shown to perform much better, in fact, to minimise the total average waiting time, simply by avoiding situations in which short jobs have to wait for very long one. However, SJF has as disadvantage that long jobs might suffer from starvation. In order to avoid the problems of both FCFS and SJF we present in this paper a new scheduling algorithm called class-based interleaving weighted fair queueing (CI-WFQ). This algorithm uses the specific characteristics of the job stream being served, that is, the distribution of the sizes of the objects being requested, to set its parameters such that good mean reponse times are obtained and starvation does not occur. In the paper, the new scheduling approach is introduced and compared, using trace-driven simulations, with existing scheduling approaches.
Probabilistic Analysis of Buffer Starvation in Markovian Queues
Xu, Yuedong; El-Azouzi, Rachid; Haddad, Majed; Elayoubi, Salaheddine; Jimenez, Tania
2011-01-01
Our purpose in this paper is to obtain the exact distribution of the number of buffer starvations within a sequence of $N$ consecutive packet arrivals. The buffer is modeled as an M/M/1 queue, plus the consideration of bursty arrivals characterized by an interrupted Poisson process. When the buffer is empty, the service restarts after a certain amount of packets are prefetched. With this goal, we propose two approaches, one of which is based on Ballot theorem, and the other uses recursive equations. The Ballot theorem approach gives an explicit solution, but at the cost of the high complexity order in certain circumstances. The recursive approach, though not offering an explicit result, needs fewer computations. We further propose a fluid analysis of starvation probability on the file level, given the distribution of file size and the traffic intensity. The starvation probabilities of this paper have many potential applications. We apply them to optimize the quality of experience (QoE) of media streaming serv...
Queueing theoretical analysis of foreign currency exchange rates
Inoue, J; Inoue, Jun-ichi; Sazuka, Naoya
2006-01-01
We propose a useful approach to investigate statistical properties of foreign currency exchange rates. Our approach is based on queueing theory, especially, the so-called renewal-reward theorem. For first passage processes of the Sony bank USD/JPY exchange rate, we evaluate the average waiting time which is defined as the average time for customers to wait until the next rate change from any time point when they want to check the rate, for example, when they login to their computer systems. We find that the assumption of exponential distribution on the first passage process should be rejected and a Weibull distribution seems to be more suitable to explain the stochastic process of the Sony bank rate. Our approach also enables us to evaluate the expected reward for customers, namely, one can predict how long customers wait and how much reward they obtain by the next price change after they login to the computer systems. We check the validity by comparing our prediction with empirical data analysis.
Optimum and equilibrium in a transport problem with queue effects
Crippa, Gianluca; Pratelli, Aldo
2008-01-01
Consider a distribution of citizens in an urban area in which some services (supermarkets, post offices...) are present. Each citizen, in order to use a service, spends an amount of time which is due both to the travel time to the service and to the queue time waiting in the service. The choice of the service to be used is made by every citizen in order to be served more quickly. Two types of problems can be considered: a global optimization of the total time spent by the citizens of the whole city (we define a global optimum and we study it with techniques from optimal mass transportation) and an individual optimization, in which each citizen chooses the service trying to minimize just his own time expense (we define the concept of equilibrium and we study it with techniques from game theory). In this framework we are also able to exhibit two time-dependent strategies (based on the notions of prudence and memory respectively) which converge to the equilibrium.
Preemptive queueing system with randomized push-out mechanism
Muliukha, Vladimir; Ilyashenko, Alexander; Zayats, Oleg; Zaborovsky, Vladimir
2015-04-01
In this article considered a queueing theory model with limited buffer size, one service channel, and two incoming flows. In this model one of the flows has a power to preempt other tasks. We call it a high-priority flow. Another one is low-priority. This priority mechanism is realized in a two different ways. The first one is a preemptive priority, which allows high-priority packets to interrupt low-priority packets in service channel and push them out. The second one is a randomized push-out mechanism with probability α, which allows us to choose what type of packets should be pushed out of the system when it is full. In this article we provide an algorithm for computing statistical characteristics of the model for all values of push-out probability α. We have used generating functions method to simplify the system of linear equations. This method allows us to reduce the order of linear equations system from k(k + 1)/2 to (k + 1). As the result we have got two effects in this model. The first one is a linear behavior of loss probabilities in the model with low overload. The second one is a "closing" of a system for low-priority packets with high overload.
Tele-Network Design Based on Queue Competition Algorithm
Huang Zhang-can; Wan Li-jun; Tang Tao; Chen Zheng-xu
2003-01-01
In this paper, we report research on how to design the tele-network. First of all, we defined the reliability of tele-network. According to the definition, we divide the whole reliability into two parts:the reliability of the mini-way and that of the whole system. Then we do algebra unintersection of the mini-way, deriving a function of reliability of tele-network. Also, we got a function of the cost of tele-network after analyzing the cost of arcs and points. Finally, we give a mathematical model to design a tele-network. For the algorithm, we define the distance of a network and adjacent area within certain boundaries . We present a new algorithm Queue Competition Algorithm(QCA)based on the adja cent area . The QCA correlates sequence of fitnesses in their fathergenerations with hunting zone of mutation and the number of individuals generated by mutation, making the stronger fitness in a small zone converge at a local extreme value, but the weaker one takes the advantage of lots of individuals and a big zone to hunt a new local extreme value. In this way, we get the overall extreme value. Numerical simulation shows that we can get the efficient hunting and exact solution by using QCA. The QCA efficient hunting and exact solution.
Network-of-queues approach to B-cell-receptor affinity discrimination
Felizzi, Federico; Comoglio, Federico
2012-06-01
The immune system is one of the most complex signal processing machineries in biology. The adaptive immune system, consisting of B and T lymphocytes, is activated in response to a large spectrum of pathogen antigens. B cells recognize and bind the antigen through B-cell receptors (BCRs) and this is fundamental for B-cell activation. However, the system response is dependent on BCR-antigen affinity values that span several orders of magnitude. Moreover, the ability of the BCR to discriminate between affinities at the high end (e.g., 109M-1-1010M-1) challenges the formulation of a mathematical model able to robustly separate these affinity-dependent responses. Queuing theory enables the analysis of many related processes, such as those resulting from the stochasticity of protein binding and unbinding events. Here we define a network of queues, consisting of BCR early signaling states and transition rates related to the propensity of molecular aggregates to form or disassemble. By considering the family of marginal distributions of BCRs in a given signaling state, we report a significant separation (measured as Jensen-Shannon divergence) that arises from a broad spectrum of antigen affinities.
Compliance with the Nuclear Waste Policy Act of 1982 (PL 97-425) will require the transportation of large volumes of spent fuel to a central receiving facility (either a geologic repository or a monitored retrievable storage facility). Decisions on the transport mode and technology will evolve over the next several years, in anticipation of the deployment of a receiving facility in the late 1990s. Regardless of the particular transportation mode or modes and the details of cask technology, the transport system from many diverse sources to a single point will generate an essentially random arrival pattern. This random arrival pattern will lead to the formation of queues at the receiving facility. As is normal in any queueing system, the waiting time distribution caused by this queueing will depend on the receiving facility input processing rate and the characteristics of the traffic. Since this is a cyclic system, there is also a reverse effect in which (for a given size cask fleet) average wait time affects traffic intensity. Both effects must be accounted for to properly represent the system. This paper develops a simple analytic queueing model which accounts for both of these effects simultaneously. Since both effects are determined by receiving facility input rates and cask fleet size and characteristics, two major sets of system design parameters are linked by the queueing process. The model is used with estimated traffic and service parameters to predict the severity of queueing under plausible reference system conditions, and to establish shadow prices for the trade off between larger cask fleets and more efficient receiving facilities. Since many of the parameter values used in this estimation are quite preliminary, these results are presented primarily in the context of demonstrating the utility of the queueing model for future trade off studies
The Effectiveness Analysis of Waiting Processes in the Different Branches of a Bank by Queue Model
Abdullah ÖZÇİL
2015-06-01
Full Text Available Despite the appreciable increase in the number of bank branches every year, nowadays queues for services don’t decrease and even become parts of our daily lives. By minimizing waiting processes the least, increasing customer satisfaction should be one of branch managers’ main goals. A quick and also customer oriented service with high quality is the most important factor for customer loyalty. In this study, Queueing theory, one of Operation Research techniques, is handled and in application, the data are obtained related to waiting in queue of customer in six different branches of two banks operating in Denizli and then they are analyzed by Queueing theory and also calculated the average effectiveness of the system. The study’s data are obtained by six branches of two banks called as A1, A2, A3, B1, B2 and B3. At the end of study it is presented to the company some advices that can bring benefits to the staff and customers. In this study, Queueing theory, one of Operation Research techniques, is handled and in application, the data are obtained related to waiting in queue of customer in three different branches of a bank operating in Denizli and then they are analyzed by Queueing theory and also calculated the average effectiveness of the system. The study’s data are obtained by three branches of the bank called A1, A2 and A3. At last it is presented to the company some advices that can bring more benefits to the staff and clients.
Compliance with the Nuclear Waste Policy Act of 1982 (PL 97-425) will require the transportation of large volumes of spent fuel to a central receiving facility (Either a geologic repository or a monitored retrievable storage facility). Decisions on the transport mode and technology will evolve over the next several years, in anticipation of the deployment of a receiving facility in the late 1990s. Regardless of the particular transportation mode or modes and the details of cask technology, the transport system from many diverse sources to a single point will generate an essentially random arrival pattern. This random arrival pattern will lead to the formation of queues at the receiving facility. As is normal in any queueing system, the waiting time distribution caused by this queueing will depend on the receiving facility input processing rate and the characteristics of the traffic. Since this is a cyclic system, there is also a reverse effect in which (for a given size cask fleet) average wait time affects traffic intensity. Both effects must be accounted for to properly represent the system. This paper develops a simple analytic queueing model which accounts for both of these effects simultaneously. Since both effects are determined by receiving facility input and cask fleet size characteristics, two major sets of system design parameters are linked by the queueing process. The model is used with estimated traffic and service parameters to predict the severity of queueing under plausible reference system conditions, and to establish ''shadow prices'' for the trade off between larger cask fleets and more efficient receiving facilities. Since many of the parameter values used in this estimation are quite preliminary, these results are presented primarily in the context of demonstrating the utility of the queueing model for future trade off studies. 5 refs., 5 figs., 2 tabs
Research on Customer Queueing System and Its Model of Commercial Bank%商业银行客户排队系统及其模型研究
杨兵; 左垒
2014-01-01
For the growing queueing problem of commercial bank,combine commercial bank management,mathematical statistics and oth-er disciplines knowledge based on the queueing theory to research. First,based on the illustration about the general structure of queueing system,describe bank queueing system architecture through a graphic. Second,research random variable distribution,including customer reaching obey Poisson distribution and the exponential distribution of service time obey. Finally,construct bank queueing system model including key quantitative indicators calculation model and objective function model. This study,fundamentally solves the contradiction between customer waiting costs and operating costs of the bank itself,and has an important role for commercial banks to optimize the re-sources allocation,improve service quality and increase customer satisfaction.%针对商业银行日益加剧的排队问题，文中以排队论理论为基础，结合商业银行管理、数理统计等学科知识进行研究。首先，在阐明排队系统一般结构的基础上，通过图形描述了银行排队系统结构；然后，研究随机变量分布，包括客户到达服从的Poisson分布和服务时间服从的指数分布；最后，构造银行排队系统模型，包括主要数量指标计算模型和目标函数模型。文中的研究内容，从根本上解决客户等待成本和银行自身经营成本之间的矛盾，对商业银行优化网点资源配置、提高服务质量、增加顾客满意度等方面具有重要作用。
Chronic Fatigue Syndrome (CFS): Managing Activities and Exercise
... message, please visit this page: About CDC.gov . Chronic Fatigue Syndrome (CFS) Share Compartir Managing Activities and Exercise ... activities. Top of Page Related Links Disability and Chronic Fatigue Syndrome Print page View page in: Español (Spanish) ...
US - Former Soviet Union environmental management activities
The Office of Environmental Management (EM) has been delegated the responsibility for US DOE's cleanup of nuclear weapons complex. The nature and the magnitude of the waste management and environmental remediation problem requires the identification of technologies and scientific expertise from domestic and foreign sources. This booklet makes comparisons and describes coordinated projects and workshops between the USA and the former Soviet Union
A New Activity-Based Financial Cost Management Method
Qingge, Zhang
The standard activity-based financial cost management model is a new model of financial cost management, which is on the basis of the standard cost system and the activity-based cost and integrates the advantages of the two. It is a new model of financial cost management with more accurate and more adequate cost information by taking the R&D expenses as the accounting starting point and after-sale service expenses as the terminal point and covering the whole producing and operating process and the whole activities chain and value chain aiming at serving the internal management and decision.
Active management of food allergy: an emerging concept.
Anagnostou, Katherine; Stiefel, Gary; Brough, Helen; du Toit, George; Lack, Gideon; Fox, Adam T
2015-04-01
IgE-mediated food allergies are common and currently there is no cure. Traditionally, management has relied upon patient education, food avoidance and the provision of an emergency medication plan. Despite this, food allergy can significantly impact on quality of life. Therefore, in recent years, evolving research has explored alternative management strategies. A more active approach to management is being adopted, which includes early introduction of potentially allergenic foods, anticipatory testing, active monitoring, desensitisation to food allergens and active risk management. This review will discuss these areas in turn. PMID:25378378
Nuclear power company activity based costing management analysis
With Nuclear Energy Industry development, Nuclear Power Company has the continual promoting stress of inner management to the sustainable marketing operation development. In view of this, it is very imminence that Nuclear Power Company should promote the cost management levels and built the nuclear safety based lower cost competitive advantage. Activity based costing management (ABCM) transfer the cost management emphases from the 'product' to the 'activity' using the value chain analysis methods, cost driver analysis methods and so on. According to the analysis of the detail activities and the value chains, cancel the unnecessary activity, low down the resource consuming of the necessary activity, and manage the cost from the source, achieve the purpose of reducing cost, boosting efficiency and realizing the management value. It gets the conclusion from the detail analysis with the nuclear power company procedure and activity, and also with the selection to 'pieces analysis' of the important cost related project in the nuclear power company. The conclusion is that the activities of the nuclear power company has the obviously performance. It can use the management of ABC method. And with the management of the procedure and activity, it is helpful to realize the nuclear safety based low cost competitive advantage in the nuclear power company. (author)
Priority Queues with Fractional Service for Tiered Delay QoS
Gary Chang
2015-12-01
Full Text Available Packet scheduling is key to quality of service (QoS capabilities of broadband wired and wireless networks. In a heterogeneous traffic environment, a comprehensive QoS packet scheduler must strike a balance between flow fairness and access delay. Many advanced packet scheduling solutions have targeted fair bandwidth allocation while protecting delay-constrained traffic by adding priority queue(s on top of a fair bandwidth scheduler. Priority queues are known to cause performance uncertainties and, thus, various modifications have been proposed. In this paper, we present a packet queueing engine dubbed Fractional Service Buffer (FSB, which, when coupled with a configurable flow scheduler, can achieve desired QoS objectives, such as fair throughputs and differentiated delay guarantees. Key performance metrics, such as delay limit and probability of delay limit violation, are derived as a function of key FSB parameters for each delay class in the packet queueing engine using diffusion approximations. OPNET simulations verify these analytical results.
US - Former Soviet Union environmental management activities
NONE
1995-09-01
The Office of Environmental Management (EM) has been delegated the responsibility for US DOE`s cleanup of nuclear weapons complex. The nature and the magnitude of the waste management and environmental remediation problem requires the identification of technologies and scientific expertise from domestic and foreign sources. This booklet makes comparisons and describes coordinated projects and workshops between the USA and the former Soviet Union.
R and D Activities for NPP Life Management in Korea
Many R and D activities related to PLiM have been carried out and implemented to Korean NPP for the long term operation. Those activities include ageing management study, periodic safety review, steam generator management programme, materials reliability programme, thinned pipe management programme, study on dissimilar metal welds, etc. Based on the R and D activities, long term operation of Kori Unit 1 was successfully started from January 17, 2008 for next 10 years beyond its original design life. In this paper, all the activities and their results of the R and D programmes are briefly introduced. (author)
ANDRA 2009 activity report: managing today to prepare the future
This activity report first presents the four-year contract between the French State and the ANDRA (the French national agency for the management of radioactive wastes), the personnel working for ANDRA. Then, it presents various activities of ANDRA in the field of the management of radioactive materials and pollutions (material and waste survey, security of polluted sites, collecting radioactive wastes and objects, public information), its operational activities (evolution and project of storage sites), its design activities for storage sites for different types of wastes (life and activity). It also describes activities in the fields of international expertise and of protection of industrial concepts
Quarterly Briefing Book on Environmental and Waste Management Activities
The purpose of the Quarterly Briefing Book on Environmental and Waste Management Activities is to provide managers and senior staff at the US Department of Energy-Richland Operations Office and its contractors with timely and concise information on Hanford Site environmental and waste management activities. Each edition updates the information on the topics in the previous edition, deletes those determined not to be of current interest, and adds new topics to keep up to date with changing environmental and waste management requirements and issues. Section A covers current waste management and environmental restoration issues. In Section B are writeups on national or site-wide environmental and waste management topics. Section C has writeups on program- and waste-specific environmental and waste management topics. Section D provides information on waste sites and inventories on the site. 15 figs., 4 tabs
Quarterly Briefing Book on Environmental and Waste Management Activities
Brown, M.C.
1991-06-01
The purpose of the Quarterly Briefing Book on Environmental and Waste Management Activities is to provide managers and senior staff at the US Department of Energy-Richland Operations Office and its contractors with timely and concise information on Hanford Site environmental and waste management activities. Each edition updates the information on the topics in the previous edition, deletes those determined not to be of current interest, and adds new topics to keep up to date with changing environmental and waste management requirements and issues. Section A covers current waste management and environmental restoration issues. In Section B are writeups on national or site-wide environmental and waste management topics. Section C has writeups on program- and waste-specific environmental and waste management topics. Section D provides information on waste sites and inventories on the site. 15 figs., 4 tabs.
Maintenance in Single-Server Queues: A Game-Theoretic Approach
Najeeb Al-Matar
2009-01-01
examine a single-server queue with bulk input and secondary work during server's multiple vacations. When the buffer contents become exhausted the server leaves the system to perform some diagnostic service of a minimum of L jobs clustered in packets of random sizes (event A. The server is not supposed to stay longer than T units of time (event B. The server returns to the system when A or B occurs, whichever comes first. On the other hand, he may not break service of a packet in a middle even if A or B occurs. Furthermore, the server waits for batches of customers to arrive if upon his return the queue is still empty. We obtain a compact and explicit form functional for the queueing process in equilibrium.
Improving Packet Processing Efficiency on Multi-core Architectures with Single Input Queue
Peter Orosz
2012-06-01
Full Text Available Generic purpose multi-core PC architectures are facing performance challenges of high rate packet reception on gigabit per second and higher speed network interfaces. In order to assign a CPU core to a networking softIRQ, the single input queue design of the low-level packet processing subsystem relies on the kernel's Symmetric Multiprocessing (SMP scheduler, which does not perform load balancing of the softIRQ instances between the CPU cores. In practice, when single receive queue is used all of the softIRQs are assigned to a single CPU core. This typical arrangement could easily drive to CPU resource exhaustion and high packet loss ratio on high bandwidth interfaces. The non-steady state of the system is triggered by the high arrival rate of the packets. This work presents a proposal for improving the packet processing efficiency in single input queue multi-core systems.
ON THE SINGLE SERVER RETRIAL QUEUE WITH PRIORITY SUBSCRIBERS AND SERVER BREAKDOWNS
Jinting WANG
2008-01-01
The author concerned the reliability evaluation as well as queueing analysis of M1, M2/G1, G2/1 retrial queues with two different types of primary customers arriving according to independent poisson flows. In the case of blocking, the first type of customers can be queued whereas the second type of customers must leave the service area but return after some random period of time to try their luck again. The author assumes that the server is unreliable and it has a service-type dependent, exponentially distributed life time as well as a service-type dependent, generally distributed repair time. The necessary and sufficient condition for the system to be stable is investigated. Using a supplementary variable method, the author obtains a steady-state solution for queueing measures, and the transient as well as the steady-state solutions for reliability measures of interest.
A Batch Arrival Retrial Queue with Two Phases of Service and Bernoulli Vacation Schedule
Gautam Choudhury; Kandarpa Deka
2013-01-01
We consider an MX/G/1 queueing system with two phases of heterogeneous service and Bernoulli vacation schedule which operate under a linear retrial policy.In addition,each individual customer is subject to a control admission policy upon the arrival.This model generalizes both the classical M/G/1 retrial queue with arrivals in batches and a two phase batch arrival queue with a single vacation under Bernoulli vacation schedule.We will carry out an extensive stationary analysis of the system,including existence of the stationary regime,embedded Markov chain,steady state distribution of the server state and number of customer in the retrial group,stochastic decomposition and calculation of the first moment.
Henrique Teixeira, Eduardo; Patrícia Favacho de Araújo, Aletéia
2015-10-01
Elasticity in computing refers to dynamically adjusting the amount of allocated resources to process a distributed application. In order to achieve this, mechanisms are needed to avoid the phenomenon of the elasticity threshold detection moving constantly up or down. The existing work fails to deliver sequential integrity of asynchronous messages processing and the asymmetries of data distribution to achieve parallel consumption. This paper fills this gaps and proposes a middleware solution to dynamically analyze the flow of message queue, and a mechanism to increase the parallelized consumption based on the output behavior. An architecture for IOD (Increase On Demand) middleware is presented, with support for the increase and decrease of thread's to cope with the growth of message queues, using the technique of limit-based heuristics over a given period of time and grouping messages into sub-queues based on classification criteria.
Some reflections on the Renewal-theory paradox in queueing theory
Robert B. Cooper
1998-01-01
Full Text Available The classical renewal-theory (waiting time, or inspection paradox states that the length of the renewal interval that covers a randomly-selected time epoch tends to be longer than an ordinary renewal interval. This paradox manifests itself in numerous interesting ways in queueing theory, a prime example being the celebrated Pollaczek-Khintchine formula for the mean waiting time in the M/G/1 queue. In this expository paper, we give intuitive arguments that explain why the renewal-theory paradox is ubiquitous in queueing theory, and why it sometimes produces anomalous results. In particular, we use these intuitive arguments to explain decomposition in vacation models, and to derive formulas that describe some recently-discovered counterintuitive results for polling models, such as the reduction of waiting times as a consequence of forcing the server to set up even when no work is waiting.
International Project Management Committee: Overview and Activities
Hoffman, Edward
2010-01-01
This slide presentation discusses the purpose and composition of the International Project Management Committee (IMPC). The IMPC was established by members of 15 space agencies, companies and professional organizations. The goal of the committee is to establish a means to share experiences and best practices with space project/program management practitioners at the global level. The space agencies that are involved are: AEB, DLR, ESA, ISRO, JAXA, KARI, and NASA. The industrial and professional organizational members are Comau, COSPAR, PMI, and Thales Alenia Space.
Does active portfolio management create value? An evaluation of fund managers' decisions
Engström, Stefan
2004-01-01
In this paper, I obtain new measures of the value of active portfolio management by forming replicating portfolios. These measures allow for a separate evaluation of fund managers' strategic and tactical decisions. I also obtain new evidence on the value of trading by decomposing it into long-term trading decisions, short-term trading decisions, and trading that is the result of regulatory restrictions. Overall, the evidence supports the value of active portfolio management and that the avera...
The Geo/Geo/1+1 Queueing System with Negative Customers
Zhanyou Ma; Yalin Guo; Pengcheng Wang; Yumei Hou
2013-01-01
We study a Geo/Geo/1+1 queueing system with geometrical arrivals of both positive and negative customers in which killing strategies considered are removal of customers at the head (RCH) and removal of customers at the end (RCE). Using quasi-birth-death (QBD) process and matrix-geometric solution method, we obtain the stationary distribution of the queue length, the average waiting time of a new arrival customer, and the probabilities of servers in busy or idle period, respectively. Finally, ...
The M/M/1 queue with inventory, lost sale and general lead times
Saffari, Mohammad; Asmussen, Søren; Haji, Rasoul
queue length (number of customers in the system) and on-hand inventory when lead times are random variables and can take various distributions. The derived stationary distributions are used to formulate long-run average performance measures and cost functions in some numerical examples.......We consider an M/M/1 queueing system with inventory under the (r,Q) policy and with lost sales, in which demands occur according to a Poisson process and service times are exponentially distributed. All arriving customers during stockout are lost. We derive the stationary distributions of the joint...
An algorithm for calculating steady state probabilities of $M|E_r|c|K$ queueing systems
Hochrainer, Stefan; Hochreiter, Ronald; Pflug, Georg
2014-01-01
This paper presents a method for calculating steady state probabilities of $M|E_r|c|K$ queueing systems. The infinitesimal generator matrix is used to define all possible states in the system and their transition probabilities. While this matrix can be written down immediately for many other $M|PH|c|K$ queueing systems with phase-type service times (e.g. Coxian, Hypoexponential, \\ldots), it requires a more careful analysis for systems with Erlangian service times. The constructed matrix may t...
Strategic behavior and social outcomes in a bottleneck queue: experimental evidence
Breinbjerg, Jesper Breinbjerg; Sebald, Alexander Christopher; Østerdal, Lars Peter
2016-01-01
first-in-first-out (FIFO), last-in-first-out (LIFO), and service-in-random-order (SIRO) queue disciplines and compare these predictions to outcomes from a laboratory experiment. In line with our theoretical predictions, we find that people arrive with greater dispersion when participating under the LIFO...... discipline, whereas they tend to arrive immediately under FIFO and SIRO. As a consequence, shorter waiting times are obtained under LIFO as compared to FIFO and SIRO. However, while our theoretical predictions admit higher welfare under LIFO, this is not recovered experimentally as the queue disciplines...
Woźniak Marcin
2014-12-01
Full Text Available In this paper, application of an evolutionary strategy to positioning a GI/M/1/N-type finite-buffer queueing system with exhaustive service and a single vacation policy is presented. The examined object is modeled by a conditional joint transform of the first busy period, the first idle time and the number of packets completely served during the first busy period. A mathematical model is defined recursively by means of input distributions. In the paper, an analytical study and numerical experiments are presented. A cost optimization problem is solved using an evolutionary strategy for a class of queueing systems described by exponential and Erlang distributions.
Calculations of Backscattering Mueller Matrices for Turbid Media with a Sphere Queue Model
WANG Qing-Hua; LI Zhen-Hua; LAI Jian-Cheng; ZHANG Ying-Ying; HE An-Zhi
2006-01-01
A sphere queue model is introduced to calculate Mueller matrices of turbid media. Combined with the single scattering approximation, the backscattering Mueller matrices of turbid media can be computed rapidly by Mie theory. The numerical results agree with the azimuthal dependences of backscattering Mueller matrices' patterns from turbid media, which indicates that the major contribution to the Mueller matrices' patterns comes from the single scattering of the sphere queue, and the multiple scattering considered as a high-order correction does not change the patterns. The numerical analysis reveals that the contrast of Mueller matrices' patterns will decrease with increase of the concentration of media and the distance from the incident point.
Some Estimation Approaches of Intensities for a Two Stage Open Queueing Network
Suresh B Pathare
2014-02-01
Full Text Available In this paper we propose a consistent and asymptotically normal estimator (CAN for intensity parameters for a queueing network with distribution-free inter-arrival and service times. Using this estimator and its estimated variance, some asymptotic confidence interval of intensities are constructed. Exact- t, Bootstrap-t, Variance-stabilized bootstrap-t, Standard bootstrap, Bayesian bootstrap, Percentile bootstrap and Bias-corrected and accelerated bootstrap are also applied to develop the confidence intervals of intensities. A comparative analysis is conducted to demonstrate performances of the confidence intervals of intensities for a queueing network with short run.
First in Line Waiting Times as a Tool for Analysing Queueing Systems
Koole, G. M.; Nielsen, Bo Friis; Nielsen, Thomas Bang
2012-01-01
We introduce a new approach to modelling queueing systems where the priority or the routing of customers depends on the time the first customer has waited in the queue. This past waiting time of the first customer in line, WFIL, is used as the primary variable for our approach. A Markov chain is...... used for modelling the system where the states represent both the number of free servers and a discrete approximation to WFIL. This approach allows us to obtain waiting time distributions for complex systems, such as the N-design routing scheme widely used, e.g., in call centers and systems with...
Zhao Yi Fan
2016-01-01
Full Text Available paper presents a new use of double queues asymmetric gated service polling system in the intelligent traffic light control system.Usually there are more vehicles in main road than minor road,so there are more green light time be needed in the main road.From the computer simulation and theory analysis,we can find that the application of double queues asymmetric gated service polling theory in intelligent traffic system can balance intersections load and set suitable passing time for vehicles to assure the roads open.
Multiple objective optimization for active sensor management
Page, Scott F.; Dolia, Alexander N.; Harris, Chris J.; White, Neil M.
2005-03-01
The performance of a multi-sensor data fusion system is inherently constrained by the configuration of the given sensor suite. Intelligent or adaptive control of sensor resources has been shown to offer improved fusion performance in many applications. Common approaches to sensor management select sensor observation tasks that are optimal in terms of a measure of information. However, optimising for information alone is inherently sub-optimal as it does not take account of any other system requirements such as stealth or sensor power conservation. We discuss the issues relating to developing a suite of performance metrics for optimising multi-sensor systems and propose some candidate metrics. In addition it may not always be necessary to maximize information gain, in some cases small increases in information gain may take place at the cost of large sensor resource requirements. Additionally, the problems of sensor tasking and placement are usually treated separately, leading to a lack of coherency between sensor management frameworks. We propose a novel approach based on a high level decentralized information-theoretic sensor management architecture that unifies the processes of sensor tasking and sensor placement into a single framework. Sensors are controlled using a minimax multiple objective optimisation approach in order to address probability of target detection, sensor power consumption, and sensor survivability whilst maintaining a target estimation covariance threshold. We demonstrate the potential of the approach through simulation of a multi-sensor, target tracking scenario and compare the results with a single objective information based approach.
Improvement of enterprise activities based on process management
Łuczak, Ja.
2015-01-01
Process management has been increasingly popular for several years now, yet most frequently it is limited to fragmentary actions, at times even to declarative activity. Few organizations have brought their management systems in conformity with the idea of process management; more frequently some particular actions within the range of process approach may be observed. Specialization allows efficient realizations of tasks; however, it separates individual organizational unities and amount...
IMPROVEMENT OF TAROM ACTIVITY BY THE REVENUE MANAGEMENT SYSTEM
CÃTÃLIN PETRUª; CRISTINA STATE
2012-01-01
The aim of our research is to highlight ways of efficiency of activity of TAROM through implementation of the Revenue Management System. Revenue Management System is an approach adopted by companies that want to optimize their revenue stream. This is achieved through a thorough understanding of the market, and involves plotting the direction to follow in order to have the best economic results in the same conditions of cost and space. One of the effects that Revenue Management System and Yiel...
Visual Impacts of Forest Management Activities: Findings on Public Preferences
United States Department of Agriculture, Forest Service
1981-01-01
A major concern of forest land managers is the visual impact that activities such as timber harvest, road building, and mining have on the forest landscape. Management of the visual resource is a regular part of planning on National Forests, and many other public and private forest land managers are increasing their efforts to protect and enhance this resource. The Forest Residue and Harvesting Research Program at the Intermountain Station includes studies of the impact of harvest and roadi...
Analysis of information systems for the enterprises marketing activities management
A.O. Natorina
2014-01-01
The article deals with the role of the computer information systems in the enterprise marketing activities strategic management, enterprises marketing management information systems. Tthe stages of the development system and launch of a new product into the market within its life cycle are analyzed, exemplified by fat and oil industry.
Facilities of management magnetoresistive transformer of active power
Val. S. Vuntesmeri
2009-03-01
Full Text Available Management facilities are considered, spectral composition is certain and the form of коммутируемого signal of magnetoresistive transformer of active power is rotined.
Guide to good practices for line and training manager activities
NONE
1998-06-01
The purpose of this guide is to provide direction for line and training managers in carrying out their responsibilities for training and qualifying personnel and to verify that existing training activities are effective.
[Approval of predator management activities in North Dakota, 2005
US Fish and Wildlife Service, Department of the Interior — Request from U.S. Fish and Wildlife Service and approval from North Dakota Game & Fish Department for predator management activities outside of the state...
Nonexercise activity thermogenesis in obesity management.
Villablanca, Pedro A; Alegria, Jorge R; Mookadam, Farouk; Holmes, David R; Wright, R Scott; Levine, James A
2015-04-01
Obesity is linked to cardiovascular disease. The global increase in sedentary lifestyle is an important factor contributing to the rising prevalence of the obesity epidemic. Traditionally, counseling has focused on moderate- to vigorous-intensity exercise, with disappointing results. Nonexercise activity thermogenesis (NEAT) is an important component of daily energy expenditure. It represents the common daily activities, such as fidgeting, walking, and standing. These high-effect NEAT movements could result in up to an extra 2000 kcal of expenditure per day beyond the basal metabolic rate, depending on body weight and level of activity. Implementing NEAT during leisure-time and occupational activities could be essential to maintaining a negative energy balance. NEAT can be applied by being upright, ambulating, and redesigning workplace and leisure-time environments to promote NEAT. The benefits of NEAT include not only the extra calories expended but also the reduced occurrence of the metabolic syndrome, cardiovascular events, and all-cause mortality. We believe that to overcome the obesity epidemic and its adverse cardiovascular consequences, NEAT should be part of the current medical recommendations. The content of this review is based on a literature search of PubMed and the Google search engine between January 1, 1960, and October 1, 2014, using the search terms physical activity, obesity, energy expenditure, nonexercise activity thermogenesis, and NEAT. PMID:25841254
MANAGING TALENT BASED ON COMPETENCIES AT INTERPOL BUCHAREST: PROPOSED ACTIVITIES
ANGELA VLÃDESCU
2012-01-01
This paper provides an overview concerning a case study related to talent in an international organization, how to attract, develop, evaluate and retain talents, taking into consideration the uniqueness of the activity performed. Starting with basic knowledge and continuing with special competencies, managing talent in an international organization is a difficult process especially when you activate in a changing environment. An appropriate manner to manage talent issues, would lead to higher...
CONTEMPORARY MANAGEMENT ASPECTS OF THE COMPANIES WITH INTERNATIONAL ACTIVITY
Sebastian ENE; Mihaela IONECI
2010-01-01
The activity of the national and international companies is determined by the manner in which their management is implemented. Obviously, the management must be structured starting from each company’s particularities in accordance with the economic environment where the respective organization develops its activity. In the contemporary times, the rigorous organization, the planning on a short-term, medium-term and long-term, the human capital quality as well as the control represent elements ...
Management Control of Public and Not-for-Profit Activities
Hofstede, G.
1981-01-01
Traditional approaches to management control usually fail for public and not-for-profit activities. The type of control applicable to such activities depends on four criteria: are objectives unambiguous, outputs measurable, effects of interventions known, and is the activity repetitive? Depending on where activities stand with regard to these criteria, the control applicable corresponds to one of six different types: routine, expert, trial-and-error, intuitive, judgemental, or political contr...
The Management System for Facilities and Activities. Safety Requirements
This publication establishes requirements for management systems that integrate safety, health, security, quality assurance and environmental objectives. A successful management system ensures that nuclear safety matters are not dealt with in isolation but are considered within the context of all these objectives. The aim of this publication is to assist Member States to establish and implement effective management systems that integrate all aspects of managing nuclear facilities and activities in a coherent manner. It details the planned and systematic actions necessary to provide adequate confidence that all these requirements are satisfied
A two-station queue with dependent preparation and service times
M. Vlasiou; I.J.B.F. Adan; O.J. Boxma
2009-01-01
We discuss a single-server multi-station alternating queue where the preparation times and the service times are auto- and cross-correlated. We examine two cases. In the first case, preparation and service times depend on a common discrete time Markov chain. In the second case, we assume that the se
Loss asymptotics for the single-server queue with complete rejection
Zwart, A.P.
2015-01-01
Consider the single-server queue in which customers are rejected if their total sojourn time would exceed a certain level K. A basic performance measure of this system is the probability PK that a customer gets rejected in steady state. This paper presents asymptotic expansions for PK as K ... If
Proposition of delay model for signalized intersections with queueing theory analytical models usage
Grzegorz SIERPIŃSKI
2007-01-01
Full Text Available Time delay on intersections is a very important transport problem. Thearticle includes a proposition of time delay model. Variance of service times is considered by used average waiting time in queue for queuing system with compressed queuing processes usage as a part of proposed time delays model.
Simple approximations for the batch-arrival mx/g/1 queue
Ommeren, van, F.J.
1988-01-01
In this paper we consider the MX/G/I queueing system with batch arrivals. We give simple approximations for the waiting-time probabilities of individual customers. These approximations are checked numerically and they are found to perform very well for a wide variety of batch-size and service-timed distributions.
Dynamic properties of chasers in a moving queue based on a delayed chasing model
Ning, Guo; Jian-Xun, Ding; Xiang, Ling; Qin, Shi; Reinhart, Kühne
2016-05-01
A delayed chasing model is proposed to simulate the chase behavior in the queue, where each member regards the closest one ahead as the target, and the leader is attracted to a target point with slight fluctuation. When the initial distances between neighbors possess an identical low value, the fluctuating target of the leader can cause an amplified disturbance in the queue. After a long period of time, the queue recovers the stable state from the disturbance, forming a straight-line-like pattern again, but distances between neighbors grow. Whether the queue can keep stable or not depends on initial distance, desired velocity, and relaxation time. Furthermore, we carry out convergence analysis to explain the divergence transformation behavior and confirm the convergence conditions, which is in approximate agreement with simulations. Project supported by the National Natural Science Foundation of China (Grant Nos. 71071044, 71001001, 71201041, and 11247291), the Doctoral Program of the Ministry of Education of China (Grant Nos. 20110111120023 and 20120111120022), the Postdoctoral Fund Project of China (Grant No. 2013M530295), the National Basic Research Program of China (Grant No. 2012CB725404), and 1000 Plan for Foreign Talent, China (Grant No. WQ20123400070).
The application of queue theory in cloud computing to reduce the waiting time
N.N. Bharkad
2014-10-01
Full Text Available Cloud computing is a new technology in computer field to provide on line service to the customers. -Cloud computing has got enormous popularity as it offers dynamic, low-cost computing solutions. To get the service of cloud the user has to be in queue until he is served. Each arriving Cloud computing User (CCU requests Cloud computing Service Provider (CCSP to use the resources, if server is available, the arriving user will seize and hold it for a length of time, which leads to queue length and more waiting time. A new arrival leaves the queue with no service. After service completion the server is made immediately available to others. From the user’s point of view he needs to be served immediately and to prevent waiting the CCSP’s can use infinite servers to reduce waiting time & queue length. The arrival pattern is often Poisson in queuing theory. In this article we analyzed the dynamic behavior of the system with infinite servers by finding various effective measures like response time, average time spend in the system, utilization and throughput.
DATADRAW: A Command Language for Manipulating and Displaying Stacks, Queues, Lists and Trees.
Siklossy, L.; And Others
DATADRAW is a command language, written in FORTRAN IV, to manipulate stacks, queues, lists and trees, and to display them on the CDC 252 scope system attached to a CDC 6600. A DATADRAW primer is given, and the algorithms for updating and displaying structures are described. It is noted that DATADRAW was designed to be a simple command language…
Algebraic modelling and performance evaluation of acyclic fork-join queueing networks
Krivulin, Nikolai K.
2012-01-01
Simple lower and upper bounds on mean cycle time in stochastic acyclic fork-join queueing networks are derived using a (max,+)-algebra based representation of network dynamics. The behaviour of the bounds under various assumptions concerning the service times in the networks is discussed, and related numerical examples are presented.
Waiting time asymptotics in the single server queue with service in random order
Boxma, OJ Onno; Foss, SG; Lasgouttes, J-M; Núñez Queija, R Rudesindo
2004-01-01
We consider the single server queue with service in random order. For a large class of heavy-tailed service time distributions, we determine the asymptotic behavior of the waiting time distribution. For the special case of Poisson arrivals and regularly varying service time distribution with index -\
The priority queue as an example of hardware/software codesign
Høeg, Flemming; Mellergaard, Niels; Staunstrup, Jørgen
1994-01-01
The paper identifies a number of issues that are believed to be important for hardware/software codesign. The issues are illustrated by a small comprehensible example: a priority queue. Based on simulations of a real application, we suggest a combined hardware/software realization of the priority...
Design of a Tree-Queue Model for a Large-Scale System
Park, Byungsung; Yoo, Jaeyeong; Kim, Hagbae
In a large queuing system, the effect of the ratio of the filled data on the queue and waiting time from the head of a queue to the service gate are important factors for process efficiency because they are too large to ignore. However, many research works assumed that the factors can be considered to be negligible according to the queuing theory. Thus, the existing queuing models are not applicable to the design of large-scale systems. Such a system could be used as a product classification center for a home delivery service. In this paper, we propose a tree-queue model for large-scale systems that is more adaptive to efficient processes compared to existing models. We analyze and design a mean waiting time equation related to the ratio of the filled data in the queue. Based on simulations, the proposed model demonstrated improvement in process-efficiency, and it is more suitable to realistic system modeling than other compared models for large-scale systems.
Efficient simulation of finite horizon problems in queueing and insurance risk
Rojas-Nandayapa, Leonardo; Asmussen, Søren
2007-01-01
Let ψ(u,t) be the probability that the workload in an initially empty M/G/1 queue exceeds u at time t<∞, or, equivalently, the ruin probability in the classical Crámer-Lundberg model. Assuming service times/claim sizes to be subexponential, various Monte Carlo estimators for ψ(u,t) are suggested. A...
A standard interface for debugger access to message queue information in MPI.
Cownie, J.; Gropp. W.
1999-06-25
This paper discusses the design and implementation of an interface that allows a debugger to obtain the information necessary to display the contents of the MPI message queues. The design has been implemented in the TotalView debugger, and dynamic libraries that conform to the interface exist for MPICH, as well as the proprietary MPI implementations from Compaq, IBM, and SGI.
Heavy Traffic Analysis Of M/G/L Queue With Markov Modulated Service Speed
Dimitrov, M.; M. Ivanova
2011-01-01
An M/G/1I queue whose service speed changes according to an external environment that is governed by a Markov process is considered. The server could change its service speed many times while serving a customer. The asymptotic behavior of the virtual workload and its mean value is investigated under heavy traffic assumptions.
A paradox for admission control of multiclass queueing network with differentiated service
Ye, Heng-Qing
2007-01-01
In this paper, we present counter-intuitive examples for the multiclass queueing network system. In the system, each station may serve more than one job class with differentiated service priority, and each job may require service sequentially by more than one service station. In our examples, the network performance is improved even when more workloads are admitted for service.
Analysis And Optimization Of Exponential Queueing Networks By Means Of Parallel Calculations
Pankov, A.; Koluzaeva, E.
2011-01-01
The method of a finding of mean characteristics of an open exponential queueing network (QN) and solution of the problem of coasts optimization in such network by means of parallel calculations is considered. The software for solution of the formulated problems, developed with usage of technology of programming MPI and libraries PETSc is described.
Boots, Nam Kyoo; Shahabuddin, Perwez
2001-01-01
This paper deals with estimating small tail probabilities of thesteady-state waiting time in a GI/GI/1 queue with heavy-tailed (subexponential) service times. The problem of estimating infinite horizon ruin probabilities in insurance risk processes with heavy-tailed claims can be transformed into th
Management of maintenance activities at Cernavoda NPP
After the Construction and Commissioning phases are over, the safety and economic performances of each nuclear unit are determined by the quality of its operation as well as by the combination of reliability and availability of the systems consisting the whole unit. Therefore, the value of a good maintenance program in making a safe and profitable operation is now widely recognized; all stations operating with excellent performance have well-defined policies and effectively administered programs to govern maintenance activities. The Cernavoda maintenance optimization initiative is derived from good practices suggested by such recognized bodies as the IAEA, INPO and EPRI. It should be noted that the program is evolving at this time and that this paper is an attempt to summarize the myriad of activities and plans required to finally implement the maintenance program. Although many of the elements of the program are in place, many are in various stages of completion. The main components of the program (policy's objectives, strategies used, specific subprograms, maintenance plans and their integration) are presented in brief along with the performance indicators used to assess the effectiveness of the program and maintenance activities. The new programs intended to be developed are also specified, as well as the main comments and recommendations received from IAEA experts. (author)
The Active Audience? Gurus, Management Ideas and Consumer Variability
Groß, C.; Heusinkveld, H.S.; Clark, T
2015-01-01
This study draws on an active audience perspective to develop a better understanding of mass audiences' attraction towards popular management ideas. It focuses on audience members' own experiences and, in particular, what audience activities actually play a role in shaping mass attraction, and how t
Activity-Based Costing: A Cost Management Tool.
Turk, Frederick J.
1993-01-01
In college and university administration, overhead costs are often charged to programs indiscriminately, whereas the support activities that underlie those costs remain unanalyzed. It is time for institutions to decrease ineffective use of resources. Activity-based management attributes costs more accurately and can improve efficiency. (MSE)
Young, Joyce A.; Hawes, Jon M.
2013-01-01
This paper describes an application of active learning within two different courses: professional selling and sales management. Students assumed the roles of sales representatives and sales managers for an actual fund-raiser--a golf outing--sponsored by a student chapter of the American Marketing Association. The sales project encompassed an…
Personality mobility as arbitrary management conduct and activity
Artyushenko A.А.
2010-05-01
Full Text Available A concept «Personality mobility» is considered in the light of pictures of arbitrary management conduct and activity of a man. The analysis of psychological pedagogical literature is conducted. Concept «co-ordination», «adroitness», «arbitrary management», «personality mobility» very near on the rich in content essence. A concept «Personality mobility» is more wide and more precisely represents the capacity of man for conscious, intentional motive activity. Exactly this concept is more clear and acceptable to description of character and essence of management motive activity. Consciousness and premeditation is considered the basic signs of arbitrary activity.
Agrawal, Rajeev; Baccelli, François; Rajan, Rajendran
1998-01-01
We introduce a queueing network model that allows us to capture the time-varying service delivered to a traffic stream due to the presence of random perturbations (e.g. cross-traffic in a communication network). We first present the model for a single queue and then describe how such queues may be interconnected using the operations of {\\em fork (or in-synchronization)} and {\\em join (or out-synchronization)}. Such networks may be seen as a generalization of stochastic event graphs, and of th...
[Active career management needed for female doctors].
Maas, Angela H E M; ter Braak, Edith W M T; Verbon, Annelies
2015-01-01
For more than 15 years two-thirds of medical students have been women. Despite this, they represent a minority (16-25 %) of professors in academic medicine. There is still a major gender gap to the disadvantage of women in leading positions in academia, with women earning only 80% of the salary of their male counterparts and fewer opportunities for scientific grants. Recent studies have shown that career ambition among men and women in medicine is comparable. However, successful women more often doubt their own achievements than men do. This is known as the 'imposter phenomenon' and acts as a barrier to career progression. Female leadership should be more actively promoted and encouraged to establish the diversity and creativity that we need in our current healthcare system. PMID:26959735
Simulation of active products cooperation for active security management
Zouinkhi, Ahmed; Ltifi, Amel; Ben Gayed, Mohamed; Abdelkrim, Naceur; Bajic, Eddy; Rondeau, Eric
2010-01-01
Wireless sensor networks (WSNs) are a new paradigm of telecommunication networks. WSNs are designed to perform efficient data collection and environment monitoring, among other applications. This article presents an approach of modelling and simulation of cooperation between active products that are equipped with a platform of sensor networks and ambient communication capabilities in order to increase their security, in a context of ambient intelligence of a deposit for chemical substances. T...
Passive and active adaptive management: Approaches and an example
Williams, B.K.
2011-01-01
Adaptive management is a framework for resource conservation that promotes iterative learning-based decision making. Yet there remains considerable confusion about what adaptive management entails, and how to actually make resource decisions adaptively. A key but somewhat ambiguous distinction in adaptive management is between active and passive forms of adaptive decision making. The objective of this paper is to illustrate some approaches to active and passive adaptive management with a simple example involving the drawdown of water impoundments on a wildlife refuge. The approaches are illustrated for the drawdown example, and contrasted in terms of objectives, costs, and potential learning rates. Some key challenges to the actual practice of AM are discussed, and tradeoffs between implementation costs and long-term benefits are highlighted. ?? 2010 Elsevier Ltd.
Radwaste management activities in the republic of Korea
Being short of natural resources, the Republic of Korea depends relatively large portion of its power generation upon nuclear energy. For the continuous utilization of nuclear energy, the public should be convinced that the necessary technologies and wherewithals are already available for the guarantee of the safe management of radwastes. The status and national policy of the radwaste management in Korea including R and D activities are covered herein. The ongoing activities of the Korea Advanced Energy Research Institute (KAERI) in the field of radwaste management include the areas of handling, treatment, storage and disposal of various radwastes, safety assessment of radwaste disposal, and the decontamination and decommissioning of nuclear facilities. In compliance with the national radwaste management programme, a centralized repository is expected to be operable by the early 1990's in the Republic. (author)
University Knowledge Management Tool for Academic Research Activity Evaluation
Mihaela OPREA
2011-01-01
The implementation of an efficient university knowledge management system involves the de-velopment of several software tools that assist the decision making process for the three main activities of a university: teaching, research, and management. Artificial intelligence provides a variety of techniques that can be used by such tools: machine learning, data mining, text mining, knowledge based systems, expert systems, case-based reasoning, decision support systems, intelligent agents etc. In...
Smart object design for active security management of hazardous products
Dobre, Dragos; Bajic, Eddy
2007-01-01
The hazardous substances are products that need special attention from the personnel which manipulates them, therefore, there is an increased need for better security management of goods and people. In this paper we propose the design of the Smart Object capable to survey its own environment according to its own security rules and to cooperate with others surounding equiped products to manage the security level in acceptable boundaries. By this way, an Active Security Environment is created, ...
Performance methods for mobility management in cellular networks
Liu, LQ; Munro, ATD; Barton, MH; McGeehan, JP
1996-01-01
This paper presents performance methods for mobility management in cellular networks. A queueing analysis is first undertaken, in which the system is modelled as an open Jackson network, consisting of M M/M/1 queues. Given environmental parameters, the corresponding probability matrix is obtained, and hence the traffic matrix equations. From these equations, the traffic load in each cell is evaluated. Secondly, a BONeS DESIGNER simulation model is created and applied to the evaluation of mobi...
Overall review on waste management in Finland - Current regulatory activities
The Finnish Centre for Radiation and Nuclear Safety is a competent authority responsible for the surveillance of the safety of nuclear installations. Its regulatory duties include surveillance of waste management operations and facilities under construction as well as safety related appraisal of future waste management concepts. The current activities of the Centre in the waste management field are concentrated on formulation of criteria for reactor waste disposal, surveillance of the construction of an interim storage for spent fuel and evaluation of the technical concepts and the preliminary site selection process for spent fuel disposal
Actively Managed Investment Portfolio Dilemmas, ‘Lost Returns Approach’
Mohamed Elmesseary
2014-10-01
Full Text Available Extending the basic belief on which the investment management business is built upon: Professional managers can beat the market; linking within a practical approach betweenthe academics’ views and practitioners’ opinions regarding the market beating inability and the reasons from behind; paying some more attention to the returns, managers lose due totheir insufficient active strategies; this work analyzes the past performance of the whole stocks that actually traded in the Egyptian market between June, 2007 and June, 2012 in order to measure how fund managers are geniuses by the zero returns they lose. It performs T-test among three types of portfolios, a well-known market index, the funds’ portfolios, and the best actively managed portfolio that can be built and used as a restrict criterion. The findings reveal that adopting the simple thought of naïve investors, away from the portfolio optimization possibilities, do generate the active portfolio, which is economically optimized, as the investors initial resources are not only significantly sufficient for accessing its investments, but can be also recovered with no more than 3 months. And which can significantly out-perform the comparable benchmarks, butunfortunately, the fund managers are not geniuses due to the impressive returns they lose.JEL classification: G1; G2Keywords: Capital markets, mutual funds, performance evaluation, market timing ability, stock picking ability
IAEA activities in the field of NPP life management
The IAEA has established programmes in the field of Nuclear Plant Lifetime in the Division of Nuclear Power and the Fuel Cycle (NEPF) and also in the Division of Nuclear Safety. In the Division of NEPF the International Working Group on Life Management of Nuclear Power Plants carries out its activities within the IAEA Project A2.03 ''Nuclear Power Plant Life Management''. Activities under this project have produced a wealth of information by organizing specialists meeting, preparing technical publications on related topics and arranging co-ordinated research programmes with good results. The most recent development is a database which has been developed and is being maintained. 4 figs
WAX ActiveLibrary: a tool to manage information overload.
Hanka, R; O'Brien, C; Heathfield, H; Buchan, I E
1999-11-01
WAX Active-Library (Cambridge Centre for Clinical Informatics) is a knowledge management system that seeks to support doctors' decision making through the provision of electronic books containing a wide range of clinical knowledge and locally based information. WAX has been piloted in several regions in the United Kingdom and formally evaluated in 17 GP surgeries based in Cambridgeshire. The evaluation has provided evidence that WAX Active-Library significantly improves GPs' access to relevant information sources and by increasing appropriate patient management and referrals this might also lead to an improvement in clinical outcomes. PMID:10662094
Fawziah M. Al-Ibraheem
2001-11-01
Full Text Available The aim of this paper is to treat the analytical solution of the truncated interarrival hyperexponential machine interference queue: H2/M/1/m+Y/m+Y in case of two branches with the following concepts: balking, reneging, state-dependent, spares, and an additional server for longer queues. Our research treats the general case for the values of m and Y considering the discipline FIFO. And some special cases have been verified.
Economou, Antonis
2003-01-01
Stochastic monotonicity properties for various classes of queueing networks have been established in the literature mainly with the use of coupling constructions. Miyazawa and Taylor (1997) introduced a class of batch-arrival, batch-service and assemble-transfer queueing networks which can be thought of as generalized Jackson networks with batch movements. We study conditions for stochastic domination within this class of networks. The proofs are based on a certain charac...
Buffer management in wireless full-duplex systems
Bouacida, Nader
2015-10-19
Wireless full-duplex radios can simultaneously transmit and receive using the same frequency. In theory, this can double the throughput. In fact, there is only little work addressing aspects other than throughput gains in full-duplex systems. Over-buffering in today\\'s networks or the so-called “bufferbloat” phenomenon creates excessive end-to-end delays resulting in network performance degradation. Our analysis shows that full-duplex systems may suffer from high latency caused by bloated buffers. In this paper, we address the problem of buffer management in full-duplex networks by using Wireless Queue Management (WQM), which is an active queue management technique for wireless networks. Our solution is based on Relay Full-Duplex MAC (RFD-MAC), an asynchronous media access control protocol designed for relay full-duplexing. We compare the performance of WQM in full-duplex environment to Drop Tail mechanism over various scenarios. Our solution reduces the end-to-end delay by two orders of magnitude while achieving similar throughput in most of the cases.
Proposals for refinements in international nuclear knowledge management activities
Concerns are raised world-wide on the sustainability of nuclear society due to the aging of nuclear manpower, coming massive retirements of senior workers within the next several years, declination of nuclear education and training, as well as the shortage of nuclear manpower supply. These concerns were reflected in the international activities such as the OECD/NEA report on the nuclear education and training and the IAEA conference on Nuclear Knowledge Management. Many more follow-up activities are currently being formulated and implemented. This paper discusses the nature of the issue, proposes a Four-Season Model of nuclear industry and manpower demand and supply, and raises an issue regarding the possibility of manpower shortage propagation from the advanced countries to the developing countries. The international activities are also reviewed and proposals for further refinements of the nuclear knowledge management activities are made
Management of spent high activity radioactive sources (SHARS)
The objective of this report is to provide all people involved in the handling and management of high activity sources with sufficient information about processes that are required for the safe management of spent high activity radioactive sources (SHARS). This includes examples of spent source management that are already taking place and also a description of the range of appropriate options that are available for each stage in the management process. This report also aims to identify the important issues to be addressed in order to develop a waste management strategy as part of the integrated management strategy that takes account of international experience and the guidance and principles that have been learned from that experience. This report relates specifically to SHARS, which are spent sources that have the potential, with short exposures, to produce acute health effects if handled incorrectly. In addition, they may also incur significant economic costs in any retrieval or environmental remediation operation, following loss of or damage to such a source. The report provides guidance on the technical, administrative and economic issues associated with SHARS from the moment they cease to be in use through to disposal, including temporary storage, transport, conditioning and interim storage
Multiple time-delays system modeling and control for router management
Ariba, Yassine; Labit, Yann
2009-01-01
This paper investigates the overload problem of a single congested router in TCP (Transmission Control Protocol) networks. To cope with the congestion phenomenon, we design a feedback control based on a multiple time-delays model of the set TCP/AQM (Active Queue Management). Indeed, using robust control tools, especially in the quadratic separation framework, the TCP/AQM model is rewritten as an intercon- nected system and a structured state feedback is constructed to stabilize the network variables. Finally, we illustrate the proposed methodology with a numerical example and simulations using NS-2 simulator.
COMMUNICATION COMPETENCES TRAINING FOR MANAGERS THROUGH ROLE-PLAY ACTIVITIES
Assist. Răzvan - Alexandru Călin Ph. D Student
2010-01-01
Communication competences are an important indicator of professional success in most areas of activity and a predictor of social success of modern man. This study is a theoretical approach aimed to substantiate a number of good practices based on role-play as an active-participatory communication competences training in general, and for managers in particular. Starting from the definition of „communication” and „competence”, it was decided to operationalize the concept of „communication compe...
Managing Suspicious Activity Reporting Systems at Small Agency Police Departments
Roberts, Bryan A.
2012-01-01
Approved for public release; distribution is unlimited Law enforcement agencies have managed anonymous tip line programs for decades whereby community members can submit suspected criminal activity to their local law enforcement agency. As a result of the increasing threat of terrorism in the United States, suspicious activity reporting programs (SAR) accompany the traditional anonymous tip line. SARs include the reporting of suspicious behavior related to terrorism, as well as other crimi...
Contributions for territorial management of risks associated with oil activity
Felipe Pinto Gonçalves
2013-06-01
Full Text Available Whereas that the growing complexity of technical and spatial organization of the oil activity in Espírito Santo state gives new demands for land use management to the local governments, this article addresses the issue of economic and technological risks associated with such activities. Based on the evaluation of legal instruments such as the classification of land uses and the zoning, are discussed the possibilities of insertion the risks in municipal policies for land use planning
Quality Management Activities for Software Architecture and Software Architecture Process
Hämäläinen, Niina
2008-01-01
Architecture processes are considerably new parts of organisations’ processes. These processes have the responsibility to aim at high quality and financially successful architectures. However, the activities which promote this aim are not clearly defined yet. This study reviews literature and practitioners’ experiences on quality management activities that could be suggested to promote the achievement of high quality software architectures and a good quality software a...
2012-06-26
... of the Secretary TRICARE Management Activity Adoption of Department of the Treasury's Administrative Wage Garnishment Procedures AGENCY: TRICARE Management Activity (TMA), DoD. ACTION: Adoption of... Treasury's Financial Management Service (FMS), to use administrative wage garnishment as an additional...
SYSTEM-FUNCTIONAL APPROACH IN ENTERPRISE''S INNOVATION ACTIVITY MANAGEMENT
Olikh, L.; Maslyukivska, А.
2012-01-01
The article is devoted to the problems of forming management system of enterprise innovation activity. The authors pick out the enterprise's innovation subsystem main parts and generalize management functions' realization in the context of its innovation activity management.
Fast distributed strategic learning for global optima in queueing access games
Tembine, Hamidou
2014-08-24
In this paper we examine combined fully distributed payoff and strategy learning (CODIPAS) in a queue-aware access game over a graph. The classical strategic learning analysis relies on vanishing or small learning rate and uses stochastic approximation tool to derive steady states and invariant sets of the underlying learning process. Here, the stochastic approximation framework does not apply due to non-vanishing learning rate. We propose a direct proof of convergence of the process. Interestingly, the convergence time to one of the global optima is almost surely finite and we explicitly characterize the convergence time. We show that pursuit-based CODIPAS learning is much faster than the classical learning algorithms in games. We extend the methodology to coalitional learning and proves a very fast formation of coalitions for queue-aware access games where the action space is dynamically changing depending on the location of the user over a graph.
Impact of sensing errors on the queueing delay and transmit power in cognitive radio access
Hamza, Doha R.
2011-03-01
We study a multiple-access system with a primary user (PU) and a secondary user (SU) utilizing the same frequency band and communicating with a common receiver. Both users transmit with a fixed transmission rate by employing a channel inversion power control scheme. The SU transmits with a certain probability that depends on the sensing outcome, its queue length and whether it has a new packet arrival. We consider the case of erroneous sensing. The goal of the SU is to find the optimal transmission scheduling policy so as to minimize its queueing delay under constraints on its average transmit power and the maximum tolerable primary outage probability caused by miss-detection. The access probabilities are obtained efficiently using linear programming. © 2011 IEEE.
Sto godina Teorije redova čekanja / A hundred years of the Queueing Theory
Nebojša V. Nikolić
2009-07-01
Full Text Available U radu je prikazan nastanak i razvoj Teorije redova čekanja, poznate i kao Teorija masovnog opsluživanja. Opisan je i istorijsko-tehnološki kontekst vremena u kojem je došlo do publikovanja prvih radova u oblasti koja će se kasnije razviti u samostalnu naučnu disciplinu. U 2009. godini Teorija redova čekanja navršava čitav vek od svog nastanka. / The paper presents a short review of histrorical development of the Queueing Theory, also known as Theory of Waiting Lines or Theory of Mass Servicing. We described historical and technological conditions at the time when first Queueing Theory papers were published. The motivation for this report comes from fact that the year 2009 is the 100th birthday of this theory.
Optimal operating policy for a controllable queueing model with a fuzzy environment
Chuen-homg LIN; Jau-chuan KE
2009-01-01
We construct the membership functions of the fuzzy objective values of a controllable queueing model, in which cost elements, arrival rate and service rate are all fuzzy numbers. Based on Zadeh's extension principle, a set of parametric nonlinear programs is developed to find the upper and lower bounds of the minimal average total cost per unit time at the possibility level. The membership functions of the minimal average total cost are further constructed using different values of the possibility level. A numerical example is solved successfully to illustrate the validity of the proposed approach. Because the object value is ex-pressed and governed by the membership functions, the optimization problem in a fuzzy environment for the controllable queueing models is represented more accurately and analytical results are more useful for system designers and practitioners.
Bindu Abraham
2014-05-01
Full Text Available In this paper we analyze DAR(1/D/s Queue with Discrete Mittag-Leffler [DML(α] as marginal distribution. Simulation study of the sample path of the arrival process is conducted. For this queueing system, the stationary distribution of the system size and the waiting time distribution of an arbitrary packet is obtained with the help of matrix analytic methods and Markov regenerative theory. The quantitative effect of the stationary distribution on system size, waiting time and the autocorrelation function as well as the parameters of the input traffic is illustrated empirically. The model is applied to a real data on the passenger arrivals at a subway bus terminal in Santiago de Chile and is established that the model well suits this data.
A Discrete-Time Queue with Balking, Reneging, and Working Vacations
Veena Goswami
2014-01-01
Full Text Available This paper presents an analysis of balking and reneging in finite-buffer discrete-time single server queue with single and multiple working vacations. An arriving customer may balk with a probability or renege after joining according to a geometric distribution. The server works with different service rates rather than completely stopping the service during a vacation period. The service times during a busy period, vacation period, and vacation times are assumed to be geometrically distributed. We find the explicit expressions for the stationary state probabilities. Various system performance measures and a cost model to determine the optimal service rates are presented. Moreover, some queueing models presented in the literature are derived as special cases of our model. Finally, the influence of various parameters on the performance characteristics is shown numerically.
A finite capacity queue with Markovian arrivals and two servers with group services
S. Chakravarthy
1994-01-01
Full Text Available In this paper we consider a finite capacity queuing system in which arrivals are governed by a Markovian arrival process. The system is attended by two exponential servers, who offer services in groups of varying sizes. The service rates may depend on the number of customers in service. Using Markov theory, we study this finite capacity queuing model in detail by obtaining numerically stable expressions for (a the steady-state queue length densities at arrivals and at arbitrary time points; (b the Laplace-Stieltjes transform of the stationary waiting time distribution of an admitted customer at points of arrivals. The stationary waiting time distribution is shown to be of phase type when the interarrival times are of phase type. Efficient algorithmic procedures for computing the steady-state queue length densities and other system performance measures are discussed. A conjecture on the nature of the mean waiting time is proposed. Some illustrative numerical examples are presented.
Kafhali, Said El; Hanini, Mohamed; Haqiq, Abdelkrim; 10.5121/ijwmn.2012.4110
2012-01-01
This paper presents a performance analysis for the bandwidth allocation in IEEE 802.16 broadband wireless access (BWA) networks considering the packet-level quality-of-service (QoS) constraints. Adaptive Modulation and Coding (AMC) rate based on IEEE 802.16 standard is used to adjust the transmission rate adaptively in each frame time according to channel quality in order to obtain multiuser diversity gain. To model the arrival process and the traffic source we use the Batch Markov Arrival Process (BMAP), which enables more realistic and more accurate traffic modelling. We determine analytically different performance parameters, such as average queue length, packet dropping probability, queue throughput and average packet delay. Finally, the analytical results are validated numerically.
Said EL KAFHALI
2012-03-01
Full Text Available This paper presents a performance analysis for the bandwidth allocation in IEEE 802.16 broadband wireless access (BWA networks considering the packet-level quality-of-service (QoS constraints. Adaptive Modulation and Coding (AMC rate based on IEEE 802.16 standard is used to adjust the transmission rate adaptively in each frame time according to channel quality in order to obtain multiuser diversity gain. To model the arrival process and the traffic source we use the Batch Markov Arrival Process (BMAP, which enables more realistic and more accurate traffic modelling. We determine analytically different performance parameters, such as average queue length, packet dropping probability, queue throughput and average packet delay. Finally, the analytical results are validated numerically.
On a BMAP/G/1 G-queue with Setup Times andMultiple Vacations
Yi PENG; Xiang-qun YANG
2011-01-01
In this paper,we consider a BMAP/G/1 G-queue with setup times and multiple vacations.Arrivals of positive customers and negative customers follow a batch Markovian arrival process (BMAP) and Markovian arrival process (MAP) respectively.The arrival of a negative customer removes all the customers in the system when the server is working.The server leaves for a vacation as soon as the system empties and is allowed to take repeated (multiple) vacations.By using the supplementary variables method and the censoring technique,we obtain the queue length distributions.We also obtain the mean of the busy period based on the renewal theory.
Queues and care: how medical residents organize their work in a busy clinic.
Finlay, W; Mutran, E J; Zeitler, R R; Randall, C S
1990-09-01
How do medical residents organize their work in settings where queue demands are heavy and resources are limited? Under such conditions, a queue theory would predict the delivery of care that is indifferent to clients' needs or that gets rid of clients as quickly as possible. In an exploratory case study of medical residents in a Veterans Administration outpatient clinic, we found instead that the medical residents' work was characterized by a high level of professional commitment: they provided thorough medical examinations and attempted to expedite patient care in other ways. We attribute the residents' professional ethos to opportunities provided in the VA hospital to learn the craft of routine medicine and to be directly responsible for patient care; such opportunities were not available in other settings. PMID:2133482
Queue-Aware Distributive Resource Control for Delay-Sensitive Two-Hop MIMO Cooperative Systems
Wang, Rui; Cui, Ying
2010-01-01
In this paper, we consider a queue-aware distributive resource control algorithm for two-hop MIMO cooperative systems. We shall illustrate that relay buffering is an effective way to reduce the intrinsic half-duplex penalty in cooperative systems. The complex interactions of the queues at the source node and the relays are modeled as an average-cost infinite horizon Markov Decision Process (MDP). The traditional approach solving this MDP problem involves centralized control with huge complexity. To obtain a distributive and low complexity solution, we introduce a linear structure which approximates the value function of the associated Bellman equation by the sum of per-node value functions. We derive a distributive two-stage two-winner auction-based control policy which is a function of the local CSI and local QSI only. Furthermore, to estimate the best fit approximation parameter, we propose a distributive online stochastic learning algorithm using stochastic approximation theory. Finally, we establish techn...
Gulab Singh Bura
2015-12-01
Full Text Available In the present paper, we consider an M/M/1/N queueing system with environmental, catastrophic and restorative effects. It is found that the change in the environment affects the state of the queueing system. The system as a whole suffers occasionally a disastrous breakdown in both the enviormentle conditions, upon which all present customers are cleared from the system and lost. A repair process then starts immidiately. Here the repair time is called the restoration time. During the repair time the customers may arrive in the system. Time dependent solution is obtained by using probability generating function technique and further the steady state probabilities of system size are also derived. Some measure of effectiveness and particular cases of the model have also been derived and discussed.
This is how we manage Sweden's radioactive waste. Activities 1995
SKB operates systems and facilities for the management and final disposal of spent nuclear fuel and other radioactive waste in Sweden. SKB has conducted extensive R, D and D work with regard to constructing a spent fuel encapsulation plant and a deep repository in crystalline bedrock. This annual report treats all the different activities without going into technical details
Draft position paper on knowledge management in space activities
Holm, Jeanne; Moura, Denis
2003-01-01
As other fields of industry, space activities are facing the challenge of Knowledge Management and the International Academy of Astronautics decided to settle in 2002 a Study Group to analyse the problem and issue general guidelines. This communication presents the draft position paper of this group in view to be discussed during the 2003 IAF Congress.
Moodog: Tracking Student Activity in Online Course Management Systems
Zhang, Hangjin; Almeroth, Kevin
2010-01-01
Many universities are currently using Course Management Systems (CMSes) to conduct online learning, for example, by distributing course materials or submitting homework assignments. However, most CMSes do not include comprehensive activity tracking and analysis capabilities. This paper describes a method to track students' online learning…
Stochastic Analysis of a Queue Length Model Using a Graphics Processing Unit
Přikryl, Jan; Kocijan, J.
2012-01-01
Roč. 5, č. 2 (2012), s. 55-62. ISSN 1802-971X R&D Projects: GA MŠk(CZ) MEB091015 Institutional support: RVO:67985556 Keywords : graphics processing unit * GPU * Monte Carlo simulation * computer simulation * modeling Subject RIV: BC - Control Systems Theory http://library.utia.cas.cz/separaty/2012/AS/prikryl-stochastic analysis of a queue length model using a graphics processing unit.pdf
Flow control in capacity-constrained queueing systems with non-stationary arrivals
Haughton, M.; K P S Isotupa
2013-01-01
In this paper, we present a flow control policy to address the problem of service capacity constraints in queueing systems that face non-stationary customer arrival rates. The studied system concerns commercial trucks arriving at international border checkpoints for processing. Based on an extensive range of numerical examples, we quantify how the flow control policy of bringing arrival rates more in line with available capacity affects customer-oriented metrics and measures of efficiency in ...
Analysis of Single-Server Queue with Phase-Type Service and Energy Harvesting
Dudin, Sergey A.; Moon Ho Lee
2016-01-01
We propose a queueing model suitable, for example, for modelling operation of nodes of sensor networks. The sensor node senses a random field and generates packets to be transmitted to the central node. The sensor node has a battery of a finite capacity and harvests energy during its operation from outside (using solar cells, wind turbines, piezoelectric cells, etc.). We assume that, generally speaking, service (transmission) of a packet consists of a random number of phases and implementatio...
Bias optimal admission control policies for a multiclass nonstationary queueing system
Lewis, Mark E.; Ayhan, Hayriye; Foley, Robert D.
2002-01-01
We consider a finite-capacity queueing system where arriving customers offer rewards which are paid upon acceptance into the system. The gatekeeper, whose objective is to `maximize' rewards, decides if the reward offered is sufficient to accept or reject the arriving customer. Suppose the arrival rates, service rates, and system capacity are changing over time in a known manner. We show that all bias optimal (a refinement of long-run average reward optimal) policies are o...
Equilibrium balking strategies in the single server Markovian queue with catastrophes
Boudali, Olga
2011-01-01
We consider a Markovian queue subject to Poisson generated catastrophes. Whenever a catastrophe occurs, all customers are forced to abandon the system, the server is rendered inoperative and an exponential repair time is set on. We assume that the arriving customers decide whether to join the system or balk, based on a natural reward-cost structure. We study the balking behavior of the customers and derive the corresponding Nash equilibrium strategies.
Transient and Stationary Losses in a Finite-Buffer Queue with Batch Arrivals
Andrzej Chydzinski; Blazej Adamczyk
2012-01-01
We present an analysis of the number of losses, caused by the buffer overflows, in a finite-buffer queue with batch arrivals and autocorrelated interarrival times. Using the batch Markovian arrival process, the formulas for the average number of losses in a finite time interval and the stationary loss ratio are shown. In addition, several numerical examples are presented, including illustrations of the dependence of the number of losses on the average batch size, buffer size, system load, aut...
Probabilistic Decomposition Method on the ServerIndices of an Mξ/G/1 Vacation Queue
2014-01-01
This paper develops a probabilistic decomposition method for an ${\\text{M}}^{\\xi }$ /G/1 repairable queueing system with multiple vacations, in which the customers who arrive during server vacations enter the system with probability p. Such a novel method is used to analyze the main performance indices of the server, such as the unavailability and the mean failure number during $(0,t]$ . It is derived that the structures of server indices are two convolution equations. Further, comparisons wi...
Evaluation of Lyapunov exponent in generalized linear dynamical models of queueing networks
Krivulin, N. K.
2012-01-01
The problem of evaluation of Lyapunov exponent in queueing network analysis is considered based on models and methods of idempotent algebra. General existence conditions for Lyapunov exponent to exist in generalized linear stochastic dynamic systems are given, and examples of evaluation of the exponent for systems with matrices of particular types are presented. A method which allow one to get the exponent is proposed based on some appropriate decomposition of the system matrix. A general app...
A tight bound on the throughput of queueing networks with blocking
Tancrez, Jean-Sébastien; Chevalier, Philippe; SEMAL, Pierre
2008-01-01
In this paper, we present a bounding methodology that allows to compute a tight lower bound on the cycle time of fork--join queueing networks with blocking and with general service time distributions. The methodology relies on two ideas. First, probability masses fitting (PMF) discretizes the service time distributions so that the evolution of the modified network can be modelled by a Markov chain. The PMF discretization is simple: the probability masses on regular intervals are computed and ...
Many-server heavy-traffic limit for queues with time-varying parameters
Liu, Yunan; Whitt, Ward
2014-01-01
A many-server heavy-traffic FCLT is proved for the $G_{t}/M/s_{t}+\\mathit{GI} $ queueing model, having time-varying arrival rate and staffing, a general arrival process satisfying a FCLT, exponential service times and customer abandonment according to a general probability distribution. The FCLT provides theoretical support for the approximating deterministic fluid model the authors analyzed in a previous paper and a refined Gaussian process approximation, using variance formulas given here. ...
Bini, D. A.; Dendievel, S.; Latouche, G.; Meini, B.
2015-01-01
The Erlangian approximation of Markovian fluid queues leads to the problem of computing the matrix exponential of a subgenerator having a block-triangular, block-Toeplitz structure. To this end, we propose some algorithms which exploit the Toeplitz structure and the properties of generators. Such algorithms allow to compute the exponential of very large matrices, which would otherwise be untreatable with standard methods. We also prove interesting decay properties of the exponential of a gene...
On one problem of the busy period determination in queues with infinitely many servers
In the paper the problem of the discretized cluster length probability determination based on the scanning in the track chambers is considered. This problem is solved in the frame of the queueing system with infinitely many servers as a discretized busy period probability determination of this system. The precise formulae of a probability are given and it is proved that those probabilities converge weakly to the probability distribution of the nondiscretized cluster when the discretization steps are diminished
A Novel Analytic Technique for the Service Station Reliability in a Discrete-Time Repairable Queue
Renbin Liu; Yinghui Tang
2013-01-01
This paper presents a decomposition technique for the service station reliability in a discrete-time repairable ${\\text{Geom}}^{X}$ /G/1 queueing system, in which the server takes exhaustive service and multiple adaptive delayed vacation discipline. Using such a novel analytic technique, some important reliability indices and reliability relation equations of the service station are derived. Furthermore, the structures of the service station indices are also found. Finally, special cases and ...
Claeys, Dieter; Laevens, Koenraad; Walraevens, Joris; Bruneel, Herwig
2010-01-01
Whereas the buffer content of batch-service queueing systems has been studied extensively, the customer delay has only occasionally been studied. The few papers concerning the customer delay share the common feature that only the moments are calculated explicitly. In addition, none of these surveys consider models including the combination of batch arrivals and a server operating under the full-batch service policy (the server waits to initiate service until he can serve at full capacity). In...
A discrete-time queue with finite-support service capacities
De Muynck, Michiel; Wittevrongel, Sabine; Bruneel, Herwig
2014-01-01
In discrete-time queueing theory, the service process is traditionally modeled using the notion of service time, the time it takes the server to completely process one customer. In our research, we take a different approach and model the service process by means of two more basic quantities: service demands and service capacities. The service demands are independent and identically distributed (i.i.d.) random variables that describe the number of work units that each customer requires from th...
Dynamic Scheduling for Markov Modulated Single-server Multiclass Queueing Systems in Heavy Traffic
Budhiraja, Amarjit; Ghosh, Arka; Liu, Xin
2012-01-01
This paper studies a scheduling control problem for a single-server multiclass queueing network in heavy traffic, operating in a changing environment. The changing environment is modeled as a finite state Markov process that modulates the arrival and service rates in the system. Various cases are considered: fast changing environment, fixed environment and slow changing environment. In each of the cases, using weak convergence analysis, in particular functional limit theorems for renewal proc...
On patient flow in hospitals: A data-based queueing-science perspective
Mor Armony
2015-12-01
Full Text Available Hospitals are complex systems with essential societal benefits and huge mounting costs. These costs are exacerbated by inefficiencies in hospital processes, which are often manifested by congestion and long delays in patient care. Thus, a queueing-network view of patient flow in hospitals is natural, for studying and improving its performance. The goal of our research is to explore patient flow data through the lenses of a queueing scientist. The means is exploratory data analysis (EDA in a large Israeli hospital, which reveals important features that are not readily explainable by existing models. Questions raised by our EDA include: Can a simple (parsimonious queueing model usefully capture the complex operational reality of the Emergency Department (ED? What time scales and operational regimes are relevant for modeling patient length of stay in the Internal Wards (IWs? How do protocols of patient transfer between the ED and the IWs influence patient delay, workload division and fairness? EDA also underscores the importance of an integrative view of hospital units by, for example, relating ED bottlenecks to IW physician protocols. The significance of such questions and our related findings raises the need for novel queueing models and theory, which we present here as research opportunities. Hospital data, and specifically patient flow data at the level of the individual patient, is increasingly collected but is typically confidential and/or proprietary. We have been fortunate to partner with a hospital that allowed us to open up its data for everyone to access. This enables reproducibility of our findings, through a user-friendly platform that is accessible through the Technion SEELab.
Nearly periodic behavior in the overloaded G/D/s+GI queue
Ward Whitt
2011-01-01
Full Text Available Under general conditions, the number of customers in a GI/D/s+GI many-server queue at time t converges to a unique stationary distribution as t → ∞. However, simulations show that the sample paths routinely exhibit nearly periodic behavior over long time intervals when the system is overloaded and s is large, provided that the system does not start in steady state. Moreover, the precise periodic behavior observed depends critically on the initial conditions. We provide insight into the transient behavior by studying the deterministic fluid model, which arises as the many-server heavy-traffic limit. The limiting fluid model also has a unique stationary point, but that stationary point is not approached from any other initial state as t → ∞. Instead, the fluid model performance approaches one of its uncountably many periodic steady states, depending on the initial conditions. Simulation experiments confirm that the time-dependent performance of the stochastic queueing model is well approximated by the fluid model. Like the fluid model, the behavior of the queueing system is highly sensitive to the initial conditions over long intervals of time.
A queueing theory description of fat-tailed price returns in imperfect financial markets
Lamba, H.
2010-09-01
In a financial market, for agents with long investment horizons or at times of severe market stress, it is often changes in the asset price that act as the trigger for transactions or shifts in investment position. This suggests the use of price thresholds to simulate agent behavior over much longer timescales than are currently used in models of order-books. We show that many phenomena, routinely ignored in efficient market theory, can be systematically introduced into an otherwise efficient market, resulting in models that robustly replicate the most important stylized facts. We then demonstrate a close link between such threshold models and queueing theory, with large price changes corresponding to the busy periods of a single-server queue. The distribution of the busy periods is known to have excess kurtosis and non-exponential decay under various assumptions on the queue parameters. Such an approach may prove useful in the development of mathematical models for rapid deleveraging and panics in financial markets, and the stress-testing of financial institutions.
A BATCH ARRIVAL RETRIAL QUEUE WITH STARTING FAILURES, FEEDBACK AND ADMISSION CONTROL
Jinting WANG; Peng-Feng ZHOU
2010-01-01
This paper is concerned with the analysis of a feedback M[X]/G/1 retrial queue with starting failures and general retrial times.In a batch,each individual customer is subject to a control admission policy upon arrival.If the server is idle,one of the customers admitted to the system may start its service and the rest joins the retrial group,whereas all the admitted customers go to the retrial group when the server is unavailable upon arrival.An arriving customer(primary or retrial)must turn-on the server,which takes negligible time.If the server is started successfully(with a certain probability),the customer gets service immediately.Otherwise,the repair for the server commences immediately and the customer must leave for the orbit and make a retrial at a later time.It is assumed that the customers who find the server unavailable are queued in the orbit in accordance with an FCFS discipline and only the customer at the head of the queue is allowed for access to the server.The Markov chain underlying the considered queueing system is studied and the necessary and sufficient condition for the system to be stable is presented.Explicit formulae for the stationary distribution and some performance measures of the system in steady-state are obtained.Finally,some numerical examples are presented to illustrate the influence of the parameters on several performance characteristics.
Huang, Xuan-Chao
2010-01-01
One of the main problems in all-optical packet-switched networks is the lack of optical buffers, and one feasible technology for the constructions of optical buffers is to use optical crossbar Switches and fiber Delay Lines (SDL). In this two-part paper, we consider SDL constructions of optical queues with a limited number of recirculations through the optical switches and the fiber delay lines. Such a problem arises from practical feasibility considerations. In Part I, we have proposed a class of greedy constructions for certain types of optical queues, including linear compressors, linear decompressors, and 2-to-1 FIFO multiplexers, and have shown that every optimal construction among our previous constructions of these types of optical queues under the constraint of a limited number of recirculations must be a greedy construction. In Part II, the present paper, we further show that there are at most two optimal constructions and give a simple algorithm to obtain the optimal construction(s). The main idea i...
Implementation of a Quality Management System in regulatory inspection activities
The Institute for Radioprotection and Dosimetry - IRD -, of the Brazilian National Nuclear Energy Commission, CNEN, started in 2001, the implementation of a quality management system (SGQ), in the inspection, testing and calibration activities. The SGQ was an institutional guideline and is inserted in a larger system of management of the IRD started in 1999, with the adoption of the National Quality Award criteria - PNQ, within the Project for Excellence in Technological Research of Associacao Brasileira das Instituicoes de Pesquisas Tecnologicas - ABIPTI (Brazilian Association of Technological Research institutions). The proposed quality management system and adopted at the IRD was developed and implemented in accordance with the requirements of NBR ISO/IEC 17025 - General requirements for the competence of testing and calibration laboratories, and ISO/IEC 17020 - General criteria for operation of various types of bodies performing inspections. For regulatory inspection activities, the quality system was implemented on three program inspection services of radiological protection led, respectively, by clinics and hospitals that operate radiotherapy services; industries that use nuclear gauges in their control or productive processes and power reactor operators (CNAAA) - just the environmental part. It was formed a pioneering team of inspectors for standardizing the processes, procedures and starting the implementation of the system in the areas. This work describes the implementation process steps, including difficulties, learning and advantages of the adoption of a quality management system in inspection activities
Implementation of benchmark management in quality assurance audit activities
The concept of Benchmark Management is that the practices of the best competitor are taken as benchmark, to analyze and study the distance between that competitor and the institute, and take efficient actions to catch up and even exceed the competitor. This paper analyzes and rebuilds all the process for quality assurance audit with the concept of Benchmark Management, based on the practices during many years of quality assurance audits, in order to improve the level and effect of quality assurance audit activities. (author)
SECONDARY WASTE MANAGEMENT STRATEGY FOR EARLY LOW ACTIVITY WASTE TREATMENT
TW, CRAWFORD
2008-07-17
This study evaluates parameters relevant to River Protection Project secondary waste streams generated during Early Low Activity Waste operations and recommends a strategy for secondary waste management that considers groundwater impact, cost, and programmatic risk. The recommended strategy for managing River Protection Project secondary waste is focused on improvements in the Effiuent Treatment Facility. Baseline plans to build a Solidification Treatment Unit adjacent to Effluent Treatment Facility should be enhanced to improve solid waste performance and mitigate corrosion of tanks and piping supporting the Effiuent Treatment Facility evaporator. This approach provides a life-cycle benefit to solid waste performance and reduction of groundwater contaminants.
Management of female handball players' activity applying interactive technologies
Frolova L.S.
2012-04-01
Full Text Available The efficiency of developed methods for the control of female handball players' readiness to competitive activity was determined. The opportunities of team management regarding the specification of playing role, the formation of the starting line of players and the replacement according to game priorities in attack or defense were considered. The availability of the adequate zone of handball players' mobilizing readiness that allows to have a significant influence on individual effectiveness in the conditions of optimal management and to increase the quality of team game was determined.
Management of nuclear PRs activity with optimal conditions
A methodology is proposed to derive optimal conditions for the activity of nuclear public relations (PRs). With the use of data-bases available at present, expressions were derived which connect the budget allocated for the PRs activity with the intensity of stimulus for four types of activity of the advertisement in the press, the exclusive publicity, the pamphlet and the advertisement on television. Optimal conditions for the activity were determined by introducing a model describing a relation between the intensity of stimulus and the extent of the change of public's attitude to nuclear energy, namely the effect of PRs activity, and also by giving the optimal ratio of allocation of the budget among the four types of activity as a function of cost versus effectiveness of each type. Those optimal conditions, being for the ratio of allocation of the budget, the execution time and the intensity of each type of activity at that time, vary depending on the number of household in a target region, the target class of demography, the duration time of activity, and the amount of budget for the activity. It becomes clear from numerical calculation that the optimal conditions and the effect of activity show quite strong non-linearity with respect to the variation of those variables, and that the effect of PRs activity averaged over all public in the target region becomes to be maximum, in Japan, when the activity is executed with the optimal conditions determined for the target class of middle- and advanced-aged women. The management of nuclear PRs activity becomes possible by introducing such a method of fixation of optimal conditions for the activity as described here. (author)
Introduction to Queueing Theory and Stochastic Teletraffic Models
Zukerman, Moshe
2013-01-01
The aim of this textbook is to provide students with basic knowledge of stochastic models that may apply to telecommunications research areas, such as traffic modelling, resource provisioning and traffic management. These study areas are often collectively called teletraffic. This book assumes prior knowledge of a programming language, mathematics, probability and stochastic processes normally taught in an electrical engineering course. For students who have some but not sufficiently strong b...
The Binary Customer Satisfaction Model in Inventory and Queueing Systems
Azadivar, Justin Sepehr
2010-01-01
This dissertation introduces the Binary Customer Satisfaction Model for addressing logistics issues. In typical logistics problems, the arrival of customers through a demand process is considered external to the management decisions. In practice, it is typically the case that customers will respond to changes is service policy by changing their behavior. The Binary Customer Satisfaction Model provides a simple customer behavior model that directly interacts with the service policy and provide...
17 CFR 240.3b-15 - Definition of ancillary portfolio management securities activities.
2010-04-01
... portfolio management securities activities. 240.3b-15 Section 240.3b-15 Commodity and Securities Exchanges... ancillary portfolio management securities activities. (a) The term ancillary portfolio management securities... of incidental trading activities for portfolio management purposes; and (3) Are limited to...
Developing knowledge management systems with an active expert methodology
Knowledge management, understood as the ability to store, distribute and utilize human knowledge in an organization, is the subject of this dissertation. In particular we have studied the design of methods and supporting software for this process. Detailed and systematic description of the design and development processes of three case-study implementations of knowledge management software are provided. The outcome of the projects is explained in terms of an active expert development methodology, which is centered around support for a domain expert to take substantial responsibility for the design and maintenance of a knowledge management system in a given area of application. Based on the experiences from the case studies and the resulting methodology, an environment for automatically supporting knowledge management was designed in the KNOWLEDGE-LINKER research project. The vital part of this architecture is a knowledge acquisition tool, used directly by the experts in creating and maintaining a knowledge base. An elaborated version of the active expert development methodology was then formulated as the result of applying the KNOWLEDGE-LINKER approach in a fourth case study. This version of the methodology is also accounted for and evaluated together within the supporting KNOWLEDGE-LINKER architecture. (au)
Waste Management Policy Framework to Mitigate Terrorist Intrusion Activities
Redus, Kenneth, S.
2003-02-26
A policy-directed framework is developed to support US Department of Energy (DOE) counterterrorism efforts, specifically terrorist intrusion activities that affect of Environmental Management (EM) programs. The framework is called the Security Effectiveness and Resource Allocation Definition Forecasting and Control System (SERAD-FACS). Use of SERAD-FACS allows trade-offs between resources, technologies, risk, and Research and Development (R&D) efforts to mitigate such intrusion attempts. Core to SERAD-FACS is (1) the understanding the perspectives and time horizons of key decisionmakers and organizations, (2) a determination of site vulnerabilities and accessibilities, and (3) quantifying the measures that describe the risk associated with a compromise of EM assets. The innovative utility of SERAD-FACS is illustrated for three integrated waste management and security strategies. EM program risks, time delays, and security for effectiveness are examined to demonstrate the significant cost and schedule impact terrorist activities can have on cleanup efforts in the DOE complex.
Microgrids in Active Network Management-Part I
Palizban, Omid; Kauhaniemia, Kimmo; Guerrero, Josep M.
2014-01-01
The microgrid concept has been closely investigated and implemented by numerous experts worldwide. The first part of this paper describes the principles of microgrid design, considering the operational concepts and requirements arising from participation in active network management. Over the las......, energy storage systems, and market participation in both island and grid-connection operation. Finally, control techniques and the principles of energy-storage systems are summarized in a comprehensive flowchart.......The microgrid concept has been closely investigated and implemented by numerous experts worldwide. The first part of this paper describes the principles of microgrid design, considering the operational concepts and requirements arising from participation in active network management. Over the last...
Management and Coordination of Nuclear Security Activities in Kenya
Over recent years the structure, format and content of the International Atomic Energy Agency (IAEA) standards have been developed further to become the global reference for the delivery of high standards of safety, radiation protection, radioactive waste management (RWM) and the safe transport of radioactive materials. Unlike safety, international standards for security do not exist. While nuclear safety deals with the design and operation of facilities and activities that prevent accidental release of radioactivity into the environment; security, however, embraces the need to protect materials and facilities from theft, misuse, attack or sabotage. In managing and coordinating nuclear security activities, these two factors have been taken into account to ensure that physical security of sources and combating of illicit trafficking of nuclear and radioactive materials. The regulatory authority, working together with relevant border and other national security organs, bilateral, the IAEA and other international organizations to contain the situation. (author)
United States-Russia: Environmental management activities, Summer 1998
NONE
1998-09-01
A Joint Coordinating Committee for Environmental Restoration and Waste Management (JCCEM) was formed between the US and Russia. This report describes the areas of research being studied under JCCEM, namely: Efficient separations; Contaminant transport and site characterization; Mixed wastes; High level waste tank remediation; Transuranic stabilization; Decontamination and decommissioning; and Emergency response. Other sections describe: Administrative framework for cooperation; Scientist exchange; Future actions; Non-JCCEM DOE-Russian activities; and JCCEM publications.
Coordinating Management Activities in Distributed Software Development Projects
Bendeck, Fawsy; Goldmann, Sigrid; Holz, Harald; Kötting, Boris
1999-01-01
Coordinating distributed processes, especially engineering and software design processes, has been a research topic for some time now. Several approaches have been published that aim at coordinating large projects in general, and large software development processes in specific. However, most of these approaches focus on the technical part of the design process and omit management activities like planning and scheduling the project, or monitoring it during execution. In this paper, we focus o...
Implementation of activity based cost management aboard base installations
Stanley, James; Perkins, Nicholas R.; Zander, Laura
2004-01-01
Approved for public release; distribution is unlimited. MBA Professional Report This project is a comparative analysis of the implementation process of Activity Based Cost Management of Marine Corps Logistics Base, (MCLB), Albany, and the implementation procedures used aboard MCB Camp Lejeune. Interviews and data gathering were conducted to identify how the respective Business Performance Offices (BPO), plan, implement, monitor, and measure performance of their process to introduce ABCM...
Management of female handball players' activity applying interactive technologies
Frolova L.S.; Glazyrin I.D.; Petrenko Y.O.; Rudenko E.; Udod M.
2012-01-01
The efficiency of developed methods for the control of female handball players' readiness to competitive activity was determined. The opportunities of team management regarding the specification of playing role, the formation of the starting line of players and the replacement according to game priorities in attack or defense were considered. The availability of the adequate zone of handball players' mobilizing readiness that allows to have a significant influence on individual effectiveness ...
United States-Russia: Environmental management activities. Summer 1998
A Joint Coordinating Committee for Environmental Restoration and Waste Management (JCCEM) was formed between the US and Russia. This report describes the areas of research being studied under JCCEM, namely: Efficient separations; Contaminant transport and site characterization; Mixed wastes; High level waste tank remediation; Transuranic stabilization; Decontamination and decommissioning; and Emergency response. Other sections describe: Administrative framework for cooperation; Scientist exchange; Future actions; Non-JCCEM DOE-Russian activities; and JCCEM publications
Briefing book on environmental and waste management activities
The purpose of the Briefing Book is to provide current information on Environmental Restoration and Waste Management Activities at the Hanford Site. Each edition updates the information in the previous edition by deleting those sections determined not to be of current interest and adding new topics to keep up to date with the changing requirements and issues. This edition covers the period from October 15, 1992 through April 15, 1993
Elena N. Rozhnova
2013-01-01
Modern trends of social development make steep demands to human capital, its competitive grow. Human resources management is one of the most important activity and economic society is in want of junior and mid-level managers. The article deals with the development and organizational issues of interconnected management of students’ preparation for management activity on the basis of updating interconnection between teacher’s control and student’s self-control. Thus, special attention is attach...
Technical Support Activities of a Nuclear Materials Management Programme
The development of a nuclear materials management programme in the United States of America has recognized from its inception the value and need of strong technical support. The success of that programme has depended to a large extent on the development of a closely allied technical support effort. This effort has drawn on the technical competency of top governmental, industrial and academic consultants, in addition to that within the USAEC. Under the planning, development and administration of the USAEC's Division of Nuclear Materials Management, a broad spectrum of technical activities has evolved. These include: (a) The establishment of an Advisory Committee for Standard Reference Materials and Methods of Measurement, (b) Preparation and USAEC co-ordination with the National Bureau of Standards in the development of a series of uranium and plutonium chemical and isotopic standards, (c) Research and development programmes designed to provide improved measurement techniques, (d) Compilation and publication of a book of selected measurement methods for uranium and plutonium. Each of these technical support activities is discussed in some detail, including the conditions that gave rise to their need and development, and their application to the USAEC's nuclear materials management programme. Included is a discussion of the USAEC's Advisory Committee for Standard Reference Materials and Methods of Measurement, which was established to provide guidance to the nuclear materials management programme and recommend research and development activities. Resulting from these recommendations was a USAEC co-operative effort with the National Bureau of Standards for the development of chemical and isotopic standard reference materials of uranium and plutonium; particular attention is devoted to the results of that joint effort. The need for research and development efforts in areas of mutual interest is examined, and the cooperation of other nations of the world is elicited in
Safe management of waste from health-care activities
The waste produced in the course of health-care activities, from contaminated needles to radioactive isotopes, carries a greater potential for causing infection and injury than any other type of waste, and inadequate or inappropriate management is likely to have serious public health consequences and deleterious effects on the environment. This handbook - the result of extensive international consultation and collaboration - provides comprehensive guidance on safe, efficient, and environmentally sound methods for the handling and disposal of health-care wastes. The various categories of waste are clearly defined and the particular hazards that each poses are described. Considerable prominence is given to the careful planning that is essential for the success of waste management; workable means of minimizing waste production are outlined and the role of reuse and recycling of waste is discussed. Most of the text, however, is devoted to the collection, segregation, storage, transport, and disposal of wastes. Details of containers for each category of waste, labelling of waste packages, and storage conditions are provided, and the various technologies for treatment of waste and disposal of final residues are discussed at length. Advice is given on occupational safety for all personnel involved with waste handling, and a separate chapter is devoted to the closely related topic of hospital hygiene and infection control. The handbook pays particular attention to basic processes and technologies that are not only safe but also affordable, sustainable, and culturally appropriate. For health-care settings in which resources are severely limited there is a separate chapter on minimal programmes; this summarizes all the simplest and least costly techniques that can be employed for the safe management of health-care wastes. The guide is aimed at public health managers and policy-makers, hospital managers, environmental health professionals, and all administrators with an
Predicting and preventing the future: actively managing multiple sclerosis.
Hutchinson, Michael
2012-02-01
Relapsing-remitting multiple sclerosis (MS) has a highly variable clinical course but a number of demographic, clinical and MRI features can guide the clinician in the assessment of disease activity and likely disability outcome. It is also clear that the inflammatory activity in the first five years of relapsing-remitting MS results in the neurodegenerative changes seen in secondary progressive MS 10-15 years later. While conventional first-line disease modifying therapy has an effect on relapses, about one third of patients have a suboptimal response to treatment. With the advent of highly active second-line therapies with their evident marked suppression of inflammation, the clinician now has the tools to manage the course of relapsing-remitting MS more effectively. The development of treatment optimisation recommendations based on the clinical response to first-line therapies can guide the neurologist in more active management of the early course of relapsing-remitting MS, with the aim of preventing both acute inflammatory axonal injury and the neurodegenerative process which leads to secondary progressive MS.
Activity Management System user reference manual. Revision 1
The Activity Management System (AMS) was developed in response to the need for a simple-to-use, low-cost, user interface system for collecting and logging Hanford Waste Vitrification Plant Project (HWVP) activities. This system needed to run on user workstations and provide common user access to a database stored on a local network file server. Most important, users wanted a system that provided a management tool that supported their individual process for completing activities. Existing system treated the performer as a tool of the system. All AMS data is maintained in encrypted format. Users can feel confident that any activities they have entered into the database are private and that, as the originator, they retain sole control over who can see them. Once entered into the AMS database, the activities cannot be accessed by anyone other than the originator, the designated agent, or by authorized viewers who have been explicitly granted the right to look at specific activities by the originator. This user guide is intended to assist new AMS users in learning how to use the application and, after the initial learning process, will serve as an ongoing reference for experienced users in performing infrequently used functions. Online help screens provide reference to some of the key information in this manual. Additional help screens, encompassing all the applicable material in this manual, will be incorporated into future AMS revisions. A third, and most important, source of help is the AMS administrator(s). This guide describes the initial production version of AMS, which has been designated Revision 1.0
Waste management activities and carbon emissions in Africa
This paper summarizes research into waste management activities and carbon emissions from territories in sub-Saharan Africa with the main objective of quantifying emission reductions (ERs) that can be gained through viable improvements to waste management in Africa. It demonstrates that data on waste and carbon emissions is poor and generally inadequate for prediction models. The paper shows that the amount of waste produced and its composition are linked to national Gross Domestic Product (GDP). Waste production per person is around half that in developed countries with a mean around 230 kg/hd/yr. Sub-Saharan territories produce waste with a biogenic carbon content of around 56% (+/-25%), which is approximately 40% greater than developed countries. This waste is disposed in uncontrolled dumps that produce large amounts of methane gas. Greenhouse gas (GHG) emissions from waste will rise with increasing urbanization and can only be controlled through funding mechanisms from developed countries.
Pollution effects on fisheries — potential management activities
Sindermann, C. J.
1980-03-01
Management of ocean pollution must be based on the best available scientific information, with adequate consideration of economic, social, and political realities. Unfortunately, the best available scientific information about pollution effects on fisheries is often fragmentary, and often conjectural; therefore a primary concern of management should be a critical review and assessment of available factual information about effects of pollutants on fish and shellfish stocks. A major problem in any such review and assessment is the separation of pollutant effects from the effects of all the other environmental factors that influence survival and well-being of marine animals. Data from long-term monitoring of resource abundance, and from monitoring of all determinant environmental variables, will be required for analyses that lead to resolution of the problem. Information must also be acquired about fluxes of contaminants through resource-related ecosystems, and about contaminant effects on resource species as demonstrated in field and laboratory experiments. Other possible management activities include: (1) encouragement of continued efforts to document clearly the localized and general effects of pollution on living resources; (2) continued pressure to identify and use reliable biological indicators of environmental degradation (indicators of choice at present are: unusually high levels of genetic and other anomalies in the earliest life history stages; presence of pollution-associated disease signs, particularly fin erosion and ulcers, in fish; and biochemical/physiological changes); and (3) major efforts to reduce inputs of pollutants clearly demonstrated to be harmful to living resources, from point sources as well as ocean dumping. Such pollution management activities, based on continuous efforts in stock assessment, environmental assessment, and experimental studies, can help to insure that rational decisions will be made about uses and abuses of coastal
Vedat Sağlam
2015-01-01
Full Text Available The aim of this paper is to analyze a tandem queueing model with two stages. The arrivals to the first stage are Poisson stream and the service time at this stage is exponential. There is no waiting room at first stage. The service time is hyperexponential and no waiting is allowed at second stage. The transition probabilities and loss probabilities of this model are obtained. In addition, the loss probability at second stage is optimized. Performance measures and the variance of the numbers of customers of this tandem queueing model are found. It is seen that the numbers of customers in first stage and second stage are dependent. Finally we have simulated this queueing model. For different values of parameters, exact values, simulated values, and optimal values of obtained performance measures of this model are numerically shown in tables and graphs.
Modelling M/G/1 queueing systems with server vacations using stochastic Petri nets
K Ramanath
2006-12-01
Full Text Available The theory of non-Markovian stochastic Petri nets is employed in this paper to derive an alternative method for studying the steady state behaviour of the M/G/1 vacation queueing system with a limited service discipline. Three types of vacation schemes are considered, and sytems with both a finite population and those with an infinite population (but finite capacity are considered. Simple numerical examples are also provided to illustrate the functionality of the methods and some useful performance measures for the system are obtained.
Optimal Policy for Mx/G/1 Queueing System with Bernoulli Feedback
Mukta Kalra
2010-01-01
Full Text Available We deal with Mx/G/1 Queueing System with Bernoulli feedback under N-Policy. The probability generating function and supplementary variable technique are utilized to evaluate the steady state probability distribution of the number of units in the system. The steady state results are used to establish the explicit expressions for the average number of units in the system and the mean response time for three different series time distribution. Some of the existing results are deduced as special cases. Cost analysis is performed to design the optimal N-policy at minimum cost. In order to validate the analytical approach by taking illustration we compute numerical results.
Equilibrium balking strategies for a clearing queueing system in alternating environment
Economou, Antonis
2011-01-01
We consider a Markovian clearing queueing system, where the customers are accumulated according to a Poisson arrival process and the server removes all present customers at the completion epochs of exponential service cycles. This system may represent the visits of a transportation facility with unlimited capacity at a certain station. The system evolves in an alternating environment that influences the arrival and the service rates. We assume that the arriving customers decide whether to join the system or balk, based on a natural linear reward-cost structure. We study the balking behavior of the customers and derive the corresponding Nash equilibrium strategies under various levels of information.
Computational Approach to Profit Optimization of a Loss-Queueing System
Dinesh Kumar Yadav
2010-01-01
Full Text Available Objective of the paper is to deal with the profit optimization of a loss queueing system with the finite capacity. Here, we define and compute total expected cost (TEC, total expected revenue (TER and consequently we compute the total optimal profit (TOP of the system. In order to compute the total optimal profit of the system, a computing algorithm has been developed and a fast converging N-R method has been employed which requires least computing time and lesser memory space as compared to other methods. Sensitivity analysis and its observations based on graphics have added a significant value to this model.
The max-plus algebra approach in modelling of queueing networks
Krivulin, Nikolai K.
2012-01-01
A class of queueing networks which consist of single-server fork-join nodes with infinite 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. We show how the matrix may be calculated from the service time of customers in the general case, and give ...
Equivalence, reversibility and symmetry properties in fork/join queueing networks with blocking
Dallery, Yves; Liu, Zhen; Towsley, Don
1990-01-01
In this paper we study quantitative as well as qualitative properties of Fork/Join queueing networks with blocking (FJQN/B's). Specifically, we prove theorems regarding the equivalence of the behavior of a FJQN/B and that of its duals of a circuit-free FJQN/B, and a strongly connected marked graph. In addition, we obtain general conditions that must be satisfied by the service times to guarantee the existence of a long term throughput and its independence on the initial configuration. We also...
Optimal scheduling in queueing network models of high-volume commercial web sites
Squillante, Mark S.; Xia, Cathy H.; Zhang, Li
2001-02-01
The optimal control of various performance-based measures in high-volume commercial web sites requires a fundamental understanding of the interactions between the diverse set of Internet services that support customer needs and the different importance levels of these services to both the customer and the e-commerce merchant. We present here a study of the control policy for each server in a multiclass queueing network that maximizes a particular function of profit, or minimizes a particular function of cost, across the different classes of Internet services.
Fernando Vela
2015-12-01
Full Text Available Multifractal studies have applications in several science and engineering fields with a tendency to increase nowadays. In this paper, it is evaluated a synthetic multifractal trace set generated by a novel algorithm in which the multifractal spectrum width of these signals is manipulated. This algorithm is also developed by the same authors and it is based on multifractal wavelet model (MWM approach. This evaluation is performed by comparing the synthetic traces with some real traces acquired from Bellcore laboratories database. A timing parameter from queueing theory was measured. The results are promising, the synthetic traces exhibit results with margin errors lower than 5%.
Congestion control scheme in ATM networks based on fast tracing-queue
Liu Zhixin; Guan Xinping
2007-01-01
One of the more challenging and unresolved issues in ATM networks is the congestion control of available bit rate (ABR). The dynamic controller is designed based on the control theory and the feedback mechanism of explicit rates.With the given method of a chosen parameter, it can guarantee the stability of the controller and closed loop system with propagation delay and bandwidth oscillation. It needs less parameters(only one) to be designed. The queue length can converge to the given value in the least steps. The fairness of different connections is considered further. The simulations show better performance and good quality of service(QoS) is achieved.
SOME NEW RESULTS ON WAITING TIME AND BUSY TIME IN M/G/1 QUEUE
无
2001-01-01
This paper considers an M/G/1 queue with Poisson rate λ ＞ 0 and servicetime distribution G(t) which is supposed to have finite mean 1/μ. The following questions are first studied: (a) The closed bounds of the probability that waiting time is more than a fixed value; (b)The total busy time of the server, which including the distribution,probability that are more than a fixed value during a given time interval (0, t], and the expected value. Some new and important results are obtained by theories of the classes of life distributions and renewal process.
A Novel Processor Scheduling Schema in Programmable Router Based on Queue Length Thresholds
Xu Ke(徐恪); Lin Chuang; Wu Jianping
2004-01-01
Programmable router may execute computing tasks except for forwarding IP packets. How to schedule the CPU in the programmable router is an important issue that needs to be solved. In this paper, the authors establish general software architecture of programmable router firstly. Based on this architecture, authors present a novel CPU scheduling algorithm based on queue length thresholds. We model this algorithm using stochastic Petri nets. The analytic results show that this scheduling algorithm can guarantee the requirements of computing of best-effort flows and QoS flows in programmable router at the same time.
Activated carbon for mercury control: Implications for fly ash management
Pflughoeft-Hassett, Debra F.; Hassett, David J.; Buckley, Tera D.; Heebink, Loreal V.; Pavlish, John H. [Energy and Environmental Research Center, 15 North 23rd Street, Stop 9018, Grand Forks, North Dakota 58202-9018 (United States)
2009-11-15
As more utilities begin to use activated carbon injection (ACI) for mercury control, the potential for the presence of elevated concentrations of mercury, other air toxic elements, and activated carbon to impact fly ash management needs to be evaluated. Several Energy and Environmental Research Center (EERC) projects have allowed the collection of comparative baseline fly ash samples and associated fly ash-activated carbon (AC) samples from full-scale demonstrations of ACI for mercury emission control. These samples were evaluated for mercury and air toxic element content and mobility and for performance criteria to facilitate a better understanding of the impact of these components to specific utilization applications, including use as a mineral admixture in concrete. These data are compared with published data from samples collected at similar large-scale mercury emission control tests. The data presented are in agreement with previous results from the EERC, the U.S. Environmental Protection Agency, and elsewhere that mercury associated with fly ash is stable and unlikely to be released under most management conditions. Additionally, this paper will discuss the potential for fly ash-AC samples to be used as a mineral admixture in concrete and other large-volume use applications. (author)
ROW (Right-of-Way) interfering construction activities management program
Rosito, Roberta; Oliveira, Marisa; Lima, Shirley [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil)
2009-07-01
A significant portion of pipeline failures occurs due to external damage. This includes third party right of way (ROW) encroachment, which shall be identified and avoided. However, injuries caused by known and planned activities do happen. Construction of crossing or sharing ROW pipelines, crossing roads and bridges, neighboring buildings and excavations of any kind might put existing pipelines in risk. This paper presents how the TRANSPETRO ROW Interfering Construction Activities Management Program is implemented by a regional ROW maintenance department responsible for more than 3,000 km of pipelines, mostly in Rio de Janeiro and Minas Gerais states. This program is based on a TRANSPETRO procedure that was written after the publication of the Official Order number 125 of ANP (Oil, Gas and Biofuel Brazilian National Agency). Tasks from design review and approval to field construction supervision are performed by the staff responsible for the routine patrols and maintenance management. The ability of foreseeing risky activities is improved by expertise gained from day-to-day work on site. (author)
Energy management and control of active distribution systems
Shariatzadeh, Farshid
Advancements in the communication, control, computation and information technologies have driven the transition to the next generation active power distribution systems. Novel control techniques and management strategies are required to achieve the efficient, economic and reliable grid. The focus of this work is energy management and control of active distribution systems (ADS) with integrated renewable energy sources (RESs) and demand response (DR). Here, ADS mean automated distribution system with remotely operated controllers and distributed energy resources (DERs). DER as active part of the next generation future distribution system includes: distributed generations (DGs), RESs, energy storage system (ESS), plug-in hybrid electric vehicles (PHEV) and DR. Integration of DR and RESs into ADS is critical to realize the vision of sustainability. The objective of this dissertation is the development of management architecture to control and operate ADS in the presence of DR and RES. One of the most challenging issues for operating ADS is the inherent uncertainty of DR and RES as well as conflicting objective of DER and electric utilities. ADS can consist of different layers such as system layer and building layer and coordination between these layers is essential. In order to address these challenges, multi-layer energy management and control architecture is proposed with robust algorithms in this work. First layer of proposed multi-layer architecture have been implemented at the system layer. Developed AC optimal power flow (AC-OPF) generates fair price for all DR and non-DR loads which is used as a control signal for second layer. Second layer controls DR load at buildings using a developed look-ahead robust controller. Load aggregator collects information from all buildings and send aggregated load to the system optimizer. Due to the different time scale at these two management layers, time coordination scheme is developed. Robust and deterministic controllers
MANAGING ENGINEERING ACTIVITIES FOR THE PLATEAU REMEDIATION CONTRACT - HANFORD
In 2008, the primary Hanford clean-up contract transitioned to the CH2MHill Plateau Remediation Company (CHPRC). Prior to transition, Engineering resources assigned to remediation/Decontamination and Decommissioning (D and D) activities were a part of a centralized engineering organization and matrixed to the performing projects. Following transition, these resources were reassigned directly to the performing project, with a loose matrix through a smaller Central Engineering (CE) organization. The smaller (10 FTE) central organization has retained responsibility for the overall technical quality of engineering for the CHPRC, but no longer performs staffing and personnel functions. As the organization has matured, there are lessons learned that can be shared with other organizations going through or contemplating performing a similar change. Benefits that have been seen from the CHPRC CE organization structure include the following: (1) Staff are closely aligned with the 'Project/facility' that they are assigned to support; (2) Engineering priorities are managed to be consistent with the 'Project/facility' priorities; (3) Individual Engineering managers are accountable for identifying staffing needs and the filling of staffing positions; (4) Budget priorities are managed within the local organization structure; (5) Rather than being considered a 'functional' organization, engineering is considered a part of a line, direct funded organization; (6) The central engineering organization is able to provide 'overview' activities and maintain independence from the engineering organizations in the field; and (7) The central engineering organization is able to maintain a stable of specialized experts that are able to provide independent reviews of field projects and day-to-day activities.
Effect of the traffic shaping function of the EF class in a DiffServ queue architecture
Kawabata, Akio; Sakaguchi, Takeshi; Yamamoto, Susumu; Shimizu, Shigeki; Nishikido, Jun; Komura, Hisashi
2002-09-01
An integrated IP (Internet Protocol) network that can handle leased-line, voice, and data traffic, offers great advantages in simplifying the networks of communication carriers and reducing network costs compared with separate service-specific networks. A key issue of such integrated IP networks will be to design a router that can efficiently handle each type of traffic strictly according to its QoS (Quality of Service). Diffserv (Differentiated Services) is a popular solution to handling multiple QoSs, so most routers tend to support it. In this paper, we propose a new DiffServ queue architecture featuring multiple EF (Expedited Forwarding) queues with traffic shaping functions. Because each EF queue has a traffic shaper, its QoS can be controlled without affecting other EF traffic. For example, when the leased line traffic is assigned to the first EF class and VoIP (Voice over IP) traffic to the second EF class, the VoIP traffic is transferred with high QoS even if the leased line traffic has bursty characteristics. This queue architecture can provide a low-latency, assured bandwidth for both leased-line and VoIP traffic. We evaluated the traffic characteristics of VoIP traffic by simulating this queue architecture using various bandwidths and voice codec types. The results indicate that this queuing mechanism can achieve lower latency and better QoS control than the usual DiffServ queue architecture without traffic shaping. The benefits of traffic shaping are more noticeable with low-bandwidth traffic.
ACTIVITY BASED MANAGEMENT – IS IT A SUITABLE APPROACH FOR CURENT CRISIS BUSINESS ENVIRONMENT?
Andrei Pelin
2013-01-01
Activity-based management is a management control technique that focuses on the resource costs of organizational activities and processes, and the improvement of quality, profitability and customer value. This technique uses activity based costing information to identify strategies for removing resource waste from operating activities. Main tools employed include: strategic analysis, value analysis, cost analysis, life-cycle costing, and activity based budgeting. As well, activity based manag...
Trapman, Pieter; Bootsma, Martinus Christoffel Jozef
2009-05-01
In this paper we establish a relation between the spread of infectious diseases and the dynamics of so called M/G/1 queues with processor sharing. The relation between the spread of epidemics and branching processes, which is well known in epidemiology, and the relation between M/G/1 queues and birth death processes, which is well known in queueing theory, will be combined to provide a framework in which results from queueing theory can be used in epidemiology and vice versa. In particular, we consider the number of infectious individuals in a standard SIR epidemic model at the moment of the first detection of the epidemic, where infectious individuals are detected at a constant per capita rate. We use a result from the literature on queueing processes to show that this number of infectious individuals is geometrically distributed. PMID:19233215
CHANGE OF CONTRACTOR FOR THE FACILITIES MANAGEMENT ACTIVITIES AT CERN
2003-01-01
The Facilities Management contract at CERN, under the responsibility of ST Division, Group FM, is in charge of the maintenance and minor works on tertiary installations (i.e. all structures and installations that have no direct relation to the running of the accelerators) for the following trades: - Technical: heating, ventilation, air conditioning, plumbing, electricity, civil engineering (painting, roofing, glazing, blinds, fencing, masonry etc.), cleansing, passenger and goods lifts, automatic and powered doors, kitchen equipment, roads, signs, keys and locks, office furniture, - Services: waste collection, security, green areas, cleaning and sanitary supplies, disinfection, rodent control and insect control. Starting from the 1st June the present contractor will stop some activities that will be taken under its responsibility by the new one, INGEST Facility. The remaining activities (including cleaning) will be moved on the 1st July. Minor perturbation in the service might occur. The contact number will ...
CHANGE OF CONTRACTOR FOR THE FACILITIES MANAGEMENT ACTIVITIES AT CERN
2003-01-01
The Facilities Management contract at CERN, under the responsibility of ST Division, Group FM, is in charge of the maintenance and minor works on tertiary installations (i.e. all structures and installations that have no direct relation to the running of the accelerators) for the following trades: - Technical: heating, ventilation, air conditioning, plumbing, electricity, civil engineering (painting, roofing, glazing, blinds, fencing, masonry etc.), cleansing, passenger and goods lifts, automatic and powered doors, kitchen equipment, roads, signs, keys and locks, office furniture, - Services: waste collection, security, green areas, cleaning and sanitary supplies, disinfection, rodent control and insect control. Starting from the 1st June the present contractor will stop some activities that will be taken under its responsibility by the new one, INGEST Facility. Others activities will be moved on the 1st July. Minor perturbation in the service might occur. The contact number will not change and will be opera...
Surgery or physical activity in the management of sciatica
Fernandez, Matthew; Ferreira, Manuela L; Refshauge, Kathryn M;
2016-01-01
PURPOSE: Previous reviews have compared surgical to non-surgical management of sciatica, but have overlooked the specific comparison between surgery and physical activity-based interventions. METHODS: Systematic review using MEDLINE, CINAHL, Embase and PEDro databases was conducted. Randomised...... controlled trials comparing surgery to physical activity, where patients were experiencing the three most common causes of sciatica-disc herniation, spondylolisthesis and spinal stenosis. Two independent reviewers extracted pain and disability data (converted to a common 0-100 scale) and assessed...... methodological quality using the PEDro scale. The size of the effects was estimated for each outcome at three different time points, with a random effects model adopted and the GRADE approach used in summary conclusions. RESULTS: Twelve trials were included. In the short term, surgery provided better outcomes...
STAFF ACTIVE AND REFLECTIVE LEARNING (ARL TO ENHANCE STUDENT MANAGEMENT
Tay Sing Leong
2010-11-01
Full Text Available The Staff Active Reflective Learning (ARL is a new scheme designed to enhance student management though regular get-togethers of a group of teaching staff. It provides a platform for staff to share issues related to teaching, and seek solutions. This addresses current and future challenges faced in classroom management. The implementation of the Staff ARL is one of the recent initiatives taken under a new approach to shared learning within the School of Electronic and Info-Comm Technology. It provides a platform for mentors to facilitate in developing fellow staff members through the provision of professional support, helping existing staff to learn and grow professionally. Insights into classroom management techniques are provided for new staff to apply while waiting to attend the formal Pedagogic Certification in Technical Education (a compulsory component for all staff. The Staff ARL fosters good working relationships, as staff can ‘chill out’ and be rewarded through the enrichment of knowledge, sharpening of capabilities, building of confidence, and growth of mutual support. The scheme received good feedback as it resulted in the creation of a range of purposeful learning tools and strategies for thedevelopment of problem solving skills, reflective thinking skills and awareness of upto-date classroom situations.
Research data management and libraries: relationships, activities, drivers and influences.
Pinfield, Stephen; Cox, Andrew M; Smith, Jen
2014-01-01
The management of research data is now a major challenge for research organisations. Vast quantities of born-digital data are being produced in a wide variety of forms at a rapid rate in universities. This paper analyses the contribution of academic libraries to research data management (RDM) in the wider institutional context. In particular it: examines the roles and relationships involved in RDM, identifies the main components of an RDM programme, evaluates the major drivers for RDM activities, and analyses the key factors influencing the shape of RDM developments. The study is written from the perspective of library professionals, analysing data from 26 semi-structured interviews of library staff from different UK institutions. This is an early qualitative contribution to the topic complementing existing quantitative and case study approaches. Results show that although libraries are playing a significant role in RDM, there is uncertainty and variation in the relationship with other stakeholders such as IT services and research support offices. Current emphases in RDM programmes are on developments of policies and guidelines, with some early work on technology infrastructures and support services. Drivers for developments include storage, security, quality, compliance, preservation, and sharing with libraries associated most closely with the last three. The paper also highlights a 'jurisdictional' driver in which libraries are claiming a role in this space. A wide range of factors, including governance, resourcing and skills, are identified as influencing ongoing developments. From the analysis, a model is constructed designed to capture the main aspects of an institutional RDM programme. This model helps to clarify the different issues involved in RDM, identifying layers of activity, multiple stakeholders and drivers, and a large number of factors influencing the implementation of any initiative. Institutions may usefully benchmark their activities against the
Study on the Calculation Models of Bus Delay at Bays Using Queueing Theory and Markov Chain
Feng Sun
2015-01-01
Full Text Available Traffic congestion at bus bays has decreased the service efficiency of public transit seriously in China, so it is crucial to systematically study its theory and methods. However, the existing studies lack theoretical model on computing efficiency. Therefore, the calculation models of bus delay at bays are studied. Firstly, the process that buses are delayed at bays is analyzed, and it was found that the delay can be divided into entering delay and exiting delay. Secondly, the queueing models of bus bays are formed, and the equilibrium distribution functions are proposed by applying the embedded Markov chain to the traditional model of queuing theory in the steady state; then the calculation models of entering delay are derived at bays. Thirdly, the exiting delay is studied by using the queueing theory and the gap acceptance theory. Finally, the proposed models are validated using field-measured data, and then the influencing factors are discussed. With these models the delay is easily assessed knowing the characteristics of the dwell time distribution and traffic volume at the curb lane in different locations and different periods. It can provide basis for the efficiency evaluation of bus bays.
Analysis of Multiserver Queueing System with Opportunistic Occupation and Reservation of Servers
Bin Sun
2014-01-01
Full Text Available We consider a multiserver queueing system with two input flows. Type-1 customers have preemptive priority and are lost during arrival only if all servers are occupied by type-1 customers. If all servers are occupied, but some provide service to type-2 customers, service of type-2 customer is terminated and type-1 customer occupies the server. If the number of busy servers is less than the threshold M during type-2 customer arrival epoch, this customer is accepted. Otherwise, it is lost or becomes a retrial customer. It will retry to obtain service. Type-2 customer whose service is terminated is lost or moves to the pool of retrial customers. The service time is exponentially distributed with the rate dependent on the customer’s type. Such queueing system is suitable for modeling cognitive radio. Type-1 customers are interpreted as requests generated by primary users. Type-2 customers are generated by secondary or cognitive users. The problem of optimal choice of the threshold M is the subject of this paper. Behavior of the system is described by the multidimensional Markov chain. Its generator, ergodicity condition, and stationary distribution are given. The system performance measures are obtained. The numerical results show the effectiveness of considered admission control.
Optimization of a forest harvesting set based on the Queueing Theory: Case study from Karelia
Shegelman Ilya
2015-12-01
Full Text Available The modern technological process of timber harvesting is a complex system both technically and organizationally. Nowadays, the study of such systems and improvement of their efficiency is impossible without the use of mathematical modeling methods. The paper presents the methodology for the optimization of logging operations based on the queueing theory. We show the adapted queueing model, which characterizes the process of logging with the use of a harvesting set consisting of harvesters and forwarders. We also present the experimental verification of the designated model that confirmed mode’s adequacy. The analysis of the effectiveness of the investigated harvesting set was conducted and the recommendations for its optimization were drawn. The research was conducted in the Pryazhinsky District in the Republic of Karelia. We showed that significant improvement of operational efficiency of the investigated harvesting set in the study area cannot be done by adjusting separate machine operations (i.e. by reducing the time of operations execution and their steadiness. However, a change in the number of machines allowed significant improvement in the operational efficiency. The most optimal harvesting set design for the experimental area consisted of two harvesters and two forwarders.
On a random area variable arising in discrete-time queues and compact directed percolation
A well-known discrete-time, single-server queueing system with mean arrival rate λ and mean departure rate μ is considered from the perspective of the area, A, swept out by the queue occupation process during a busy period. We determine the exact form of the tail of the distribution, Pr(A > x); in particular, we show that Pr(A > x) ∼ Cx-1/4 exp(-Dx1/2) for all ρ ≠ 1, where ρ ≡ λ/μ, and expressions for C and D are given. For the critical case ρ = 1 we show that Pr(A > x) ∼ C'x-1/3, with C' also given. A simple mapping, used in the derivation, establishes a connection with compact directed percolation on a square lattice. As a corollary, therefore, we are also able to specify the large-area asymptotic behaviour of this model at all points in the phase diagram. This extends previous scaling results, which are only valid close to the percolation threshold
Liou, Cheng-Dar
2015-09-01
This study investigates an infinite capacity Markovian queue with a single unreliable service station, in which the customers may balk (do not enter) and renege (leave the queue after entering). The unreliable service station can be working breakdowns even if no customers are in the system. The matrix-analytic method is used to compute the steady-state probabilities for the number of customers, rate matrix and stability condition in the system. The single-objective model for cost and bi-objective model for cost and expected waiting time are derived in the system to fit in with practical applications. The particle swarm optimisation algorithm is implemented to find the optimal combinations of parameters in the pursuit of minimum cost. Two different approaches are used to identify the Pareto optimal set and compared: the epsilon-constraint method and non-dominate sorting genetic algorithm. Compared results allow using the traditional optimisation approach epsilon-constraint method, which is computationally faster and permits a direct sensitivity analysis of the solution under constraint or parameter perturbation. The Pareto front and non-dominated solutions set are obtained and illustrated. The decision makers can use these to improve their decision-making quality.
A Single-server Discrete-time Retrial G-queue with Server Breakdowns and Repairs
Jin-ting Wang; Peng Zhang
2009-01-01
This paper concerns a discrete-time Geo/Geo/1 retrial queue with both positive and negative customers where the server is subject to breakdowns and repairs due to negative arrivals.The arrival of a negative customer causes one positive customer to be killed if any is present,and simultaneously breaks the server down.The server is sent to repair immediately and after repair it is as good as new.The negative customer also causes the server breakdown if the server is found idle,but has no effect on the system if the server is under repair.We analyze the Markov chain underlying the queueing system and obtain its ergodicity condition.The generating function of the number of customers in the orbit and in the system are also obtained,along with the marginal distributions of the orbit size when the server is idle,busy or down.Finally,we present some numerical examples to illustrate the influence of the parameters on several performance characteristics of the system.
A Voice Priority Queue (VPQ Fair Scheduler for the VoIP over WLANs
Kashif Nisar
2011-02-01
Full Text Available Transmission of VoIP over packet switching networks is one of the rapidly emerging real-time Internet Protocol. The real-time application of the Voice over Internet Protocol (VoIP is growing rapidly for it is more flexible than the traditional Public Switched Telephone Networks systems (PSTN. Meanwhile, the VoIP deployment on Wireless Local Area Networks (WLANs, which is based on IEEE 802.11 standards, is increasing. Currently, many schedulers have been introduced such as Weighted Fair Queueing (WFQ, Strict Priority (SP General processor sharing (GPS, Deficit Round Robin (DRR, andContention-Aware Temporally fair Scheduling (CATS. Unfortunately, the current scheduling techniques have some drawbacks on real-time applications and therefore will not be able to handle the VoIP packetsin a proper way. The objective of this research is to propose a new scheduler system model for the VoIP application named Voice Priority Queue (VPQ scheduler. The scheduler system model is to ensureefficiency by producing a higher throughput and fairness for VoIP packets. In this paper, only the First Stage of the VPQ packet scheduler and its algorithm are presented. Simulation topologies for VoIP traffic were implemented and analyzed using the Network Simulator (NS-2. The results show that this method can achieve a better and more accurate VoIP quality throughput and fairness index.
Study on the Calculation Models of Bus Delay at Bays Using Queueing Theory and Markov Chain
Sun, Li; Sun, Shao-wei; Wang, Dian-hai
2015-01-01
Traffic congestion at bus bays has decreased the service efficiency of public transit seriously in China, so it is crucial to systematically study its theory and methods. However, the existing studies lack theoretical model on computing efficiency. Therefore, the calculation models of bus delay at bays are studied. Firstly, the process that buses are delayed at bays is analyzed, and it was found that the delay can be divided into entering delay and exiting delay. Secondly, the queueing models of bus bays are formed, and the equilibrium distribution functions are proposed by applying the embedded Markov chain to the traditional model of queuing theory in the steady state; then the calculation models of entering delay are derived at bays. Thirdly, the exiting delay is studied by using the queueing theory and the gap acceptance theory. Finally, the proposed models are validated using field-measured data, and then the influencing factors are discussed. With these models the delay is easily assessed knowing the characteristics of the dwell time distribution and traffic volume at the curb lane in different locations and different periods. It can provide basis for the efficiency evaluation of bus bays. PMID:25759720
Jahn, Beate; Theurl, Engelbert; Siebert, Uwe; Pfeiffer, Karl-Peter
2010-01-01
In most decision-analytic models in health care, it is assumed that there is treatment without delay and availability of all required resources. Therefore, waiting times caused by limited resources and their impact on treatment effects and costs often remain unconsidered. Queuing theory enables mathematical analysis and the derivation of several performance measures of queuing systems. Nevertheless, an analytical approach with closed formulas is not always possible. Therefore, simulation techniques are used to evaluate systems that include queuing or waiting, for example, discrete event simulation. To include queuing in decision-analytic models requires a basic knowledge of queuing theory and of the underlying interrelationships. This tutorial introduces queuing theory. Analysts and decision-makers get an understanding of queue characteristics, modeling features, and its strength. Conceptual issues are covered, but the emphasis is on practical issues like modeling the arrival of patients. The treatment of coronary artery disease with percutaneous coronary intervention including stent placement serves as an illustrative queuing example. Discrete event simulation is applied to explicitly model resource capacities, to incorporate waiting lines and queues in the decision-analytic modeling example. PMID:20345550
Cheng, Jay; Yang, Sheng-Hua; Chao, Tsz-Hsuan; Lee, Duan-Shin; Lien, Ching-Min
2010-01-01
In this two-part paper, we consider SDL constructions of optical queues with a limited number of recirculations through the optical switches and the fiber delay lines. We show that the constructions of certain types of optical queues, including linear compressors, linear decompressors, and 2-to-1 FIFO multiplexers, under a simple packet routing scheme and under the constraint of a limited number of recirculations can be transformed into equivalent integer representation problems under a corresponding constraint. Given $M$ and $k$, the problem of finding an \\emph{optimal} construction, in the sense of maximizing the maximum delay (resp., buffer size), among our constructions of linear compressors/decompressors (resp., 2-to-1 FIFO multiplexers) is equivalent to the problem of finding an optimal sequence ${\\dbf^*}_1^M$ in $\\Acal_M$ (resp., $\\Bcal_M$) such that $B({\\dbf^*}_1^M;k)=\\max_{\\dbf_1^M\\in \\Acal_M}B(\\dbf_1^M;k)$ (resp., $B({\\dbf^*}_1^M;k)=\\max_{\\dbf_1^M\\in \\Bcal_M}B(\\dbf_1^M;k)$), where $\\Acal_M$ (resp., ...
An MPI Implementation of a Self-Submitting Parallel Job Queue
Neuberger, John M; Swift, James W
2012-01-01
We present a simple and easy to apply methodology for using high-level self-submitting parallel job queues in an MPI environment. Using C++, we implemented a library of functions, MPQueue, both for testing our concepts and for use in real applications. In particular, we have applied our ideas toward solving computational combinatorics problems and for finding bifurcation diagrams of solutions of partial differential equations (PDE). Our method is general and can be applied in many situations without a lot of programming effort. The key idea is that workers themselves can easily submit new jobs to the currently running job queue. Our applications involve complicated data structures, so we employ serialization to allow data to be effortlessly passed between nodes. Using our library, one can solve large problems in parallel without being an expert in MPI. We demonstrate our methodology and the features of the library with several example programs, and give some results from our current PDE research. We show that...
Optimal Control of a Single Queue with Retransmissions: Delay-Dropping Tradeoffs
Giovanidis, Anastasios; Buehler, Joerg
2009-01-01
A single queue incorporating a retransmission protocol is investigated, assuming that the sequence of per effort success probabilities in the Automatic Retransmission reQuest (ARQ) chain is a priori defined and no channel state information at the transmitter is available. A Markov Decision Problem with an average cost criterion is formulated where the possible actions are to either continue the retransmission process of an erroneous packet at the next time slot or to drop the packet and move on to the next packet awaiting for transmission. The cost per slot is a linear combination of the current queue length and a penalty term in case dropping is chosen as action. The investigation seeks policies that provide the best possible average packet delay-dropping trade-off for Quality of Service guarantees. An optimal deterministic stationary policy is shown to exist, several structural properties of which are obtained. Based on that, a class of suboptimal -policies is introduced. These suggest that it is almost opt...
Features of risk-management in innovative activity: regional aspect
Darmilova Zhenni, D.; Kolesnikov Yuriy, S.
2015-01-01
The main problems of risk management in modern conditions, especially in risk management innovation, tools, exposure to risks, directions of state support in the management of risk in a public- private partnership are considered in the paper.
EC-sponsored research activities on accident management measures
The European Commission (EC) is currently funding, via the 1994-1998 R and D Framework Programme, a number of activities in the field of Nuclear Fission Safety (NFS), and particularly in several areas related to 'Reactor Safety Severe Accidents'. This programme continues the research activities of the previous Community Reactor Safety Programme which was carried out as a Reinforced Concerted Action (RCA) during the period 1992-1995. The group of multi-partners projects selected for financial support from the EC under Area B.5.1 of the current NFS Programme, 'Supporting Activities / Accident Management Measures' (known as the 'AMM' cluster) are basically aiming at implementing the results of severe accident research into practical Accident Management (AM) strategies. The generic objective is to exchange information and to develop a common European approach regarding aspects such as phenomena related uncertainties, possible adverse effects of operator actions on the progression of the accident, interpretation of measurements, equipment performance, instrument survival and human error under stress. This paper briefly discusses the objectives and achievements of a completed project of the 1992-1995 RCA, known as 'Accident Management Support' ('AMS'), and also presents the current status of an on-going project of the 1994-1998 NFS Programme, 'Algorithm support for accident identification and Critical safety Functions signal validation' ('ASIA'). The objectives of the 'AMS' project were (i) to define, investigate and develop means and methods to provide reliable information and diagnostics, as well as support tools for accident management, and (ii) investigate the different signal validation methodologies with emphasis on the existing instrumentation rather than on new instrumentation needs. The work started with the writing of two state-of-the-art reports (SOARs) in these two areas. In parallel to the compilation of the SOARs, and later in a second phase, specific
带启动时间的N-策略M/G/1排队系统的队长%Queue size of M/G/1 queueing system with N-policy and set-up times
唐应辉; 蒲会; 余玅妙
2011-01-01
This paper considered the M/G/1 queue with N-policy and set-up times, and directly studied both the tranaient distribution and equilibrium distribution of the queue length. By introducing the server busy period, and u8ing the total probability decomposition technique and Laplace transform, the recursion expressions of the Laplace transform of the transient queue length diatribution at any time t are obtained.Furthermore, the recursion expressions 0f the distribution and stochastic decomposition of the queue length at a random point in equilibrium are also obtained, which have important value on application. Especially,some corresponding results which have more really value in some special queueing models are obtained directly.%考虑带启动时间的N-策略M/G/1排队系统,从任意初始状态出发,直接研究了系统队长的瞬态分布和稳态分布.通过引进的"服务员忙期",使用全概率分解技术和拉普拉斯变换,导出了在任意时刻t队长的瞬态分布的拉普拉斯变换的表达式,进一步获得了有重要应用价值的稳态分布的具体的递推式子,以及稳态队长的随机分解结果.特别地,还直接获得了一些特殊排队系统的更实用的稳态队长分布的递推表达式.
J. Ben Atkinson
1995-01-01
Full Text Available We consider the transient analysis of the M/G/1/0 queue, for which Pn(t denotes the probability that there are no customers in the system at time t, given that there are n(n=0,1 customers in the system at time 0. The analysis, which is based upon coupling theory, leads to simple bounds on Pn(t for the M/G/1/0 and M/PH/1/0 queues and improved bounds for the special case M/Er/1/0. Numerical results are presented for various values of the mean arrival rate λ to demonstrate the increasing accuracy of approximations based upon the above bounds in light traffic, i.e., as λ→0. An important area of application for the M/G/1/0 queue is as a reliability model for a single repairable component. Since most practical reliability problems have λ values that are small relative to the mean service rate, the approximations are potentially useful in that context. A duality relation between the M/G/1/0 and GI/M/1/0 queues is also described.
Active traffic management on road networks: a macroscopic approach.
Kurzhanskiy, Alex A; Varaiya, Pravin
2010-10-13
Active traffic management (ATM) is the ability to dynamically manage recurrent and non-recurrent congestion based on prevailing traffic conditions in order to maximize the effectiveness and efficiency of road networks. It is a continuous process of (i) obtaining and analysing traffic measurement data, (ii) operations planning, i.e. simulating various scenarios and control strategies, (iii) implementing the most promising control strategies in the field, and (iv) maintaining a real-time decision support system that filters current traffic measurements to predict the traffic state in the near future, and to suggest the best available control strategy for the predicted situation. ATM relies on a fast and trusted traffic simulator for the rapid quantitative assessment of a large number of control strategies for the road network under various scenarios, in a matter of minutes. The open-source macrosimulation tool Aurora ROAD NETWORK MODELER is a good candidate for this purpose. The paper describes the underlying dynamical traffic model and what it takes to prepare the model for simulation; covers the traffic performance measures and evaluation of scenarios as part of operations planning; introduces the framework within which the control strategies are modelled and evaluated; and presents the algorithm for real-time traffic state estimation and short-term prediction. PMID:20819824
Another Look at the Performance of Actively Managed Equity Mutual Funds
D.C. Blitz (David); J.J. Huij (Joop)
2012-01-01
textabstractIn this study we evaluate the performance of actively managed equity mutual funds against a set of passively managed index funds. We find that the return spread between the best performing actively managed funds and a factor-mimicking portfolio of passive funds is positive and as large a
A three-dimensional probabilistic fuzzy control system for network queue management
Yun ZHANG; Zhi LIU; Yaonan WANG
2009-01-01
A novel probabilistic fuzzy control system is proposed to treat the congestion avoidance problem in trans-mission control protocol(TCP) networks.Studies on traffic measurement of TCP networks have shown that the packet traffic exhibits long range dependent properties called self-similarity,which degrades the network performance greatly.The probabilistic fuzzy control(PFC) system is used to handle the complex stochastic features of self-similar traffic and the modeling uncertainties in the network system.A three-dimensional(3-D) membership function(MF) is embedded in the PFC to express and describe the stochastic feature of network traffic.The 3-D MF has extended the traditional fuzzy planar mapping and further provides a spatial mapping among "fuzziness-randomness-state".The additional stochastic expression of 3-D MF provides the PFC an additional freedom to handle the stochastic features of self-similar traffic.Simulation ex-periments show that the proposed control method achieves superior performance compared to traditional control schemes in a stochastic environment.
Estimating cost for integrated harvesting and related forest management activities
Often the deciding factor in the economical recovery of wood fuel is its relationship with some other objective such as stand establishment, stand improvement, or forest access. The costs and benefits arising from these related management activities are discussed. Two different approaches to estimating the cost of producing conventional products and fuel wood with integrated harvesting systems are also examined. With a marginal cost approach, the cost of common harvesting activities such as felling, forwarding and processing/sorting are fully allocated to the conventional products. Under a joint product approach, the cost of production is distributed among conventional products and fuel wood. A model is developed showing the distribution of cost under both approaches for seven integrated harvesting systems. The results suggest that production costs are highly variable depending on the harvesting system used and the ratio of conventional products to fuel wood. The estimated cost of fuel wood varies from $6.74 (U.S. dollars) gt-1 to $37.05 gt-1 using joint product costing and from nil to $11.04 under the marginal cost method. (Author)
Activation and waste management considerations of fusion materials
Cheng, E. T.; Saji, G.
1994-09-01
Inconel-625 (Ni625), SS316, Ti-6Al-4V (Ti64), ferritic steel (FS), reduced activity ferritic steel (RAFS), manganese steel (Mn-steel), and V5Cr5Ti (V55), were examined for a near-term experimental D-T fueled fusion power reactor with respect to waste management. Activation calculations for these materials were performed assuming one year continuous operation at 1 MW/m 2 wall loading. The results show that the blanket components made of V55, Ti64, Mn-steel, and FS will be allowed for transfer to an on-site dry storage facility after 10 years of cooling after discharge. To transport the discharged blanket components to a permanent disposal site, the cooling time needed can be within 10 years for Ti64 and V55, provided that the impurities (mainly Ni, Nb and Mo) be controlled to an acceptable level. The RAFS and Mn-steel will need about 30 y cooling time because of its Fe and Mn contents. Ni625, 316SS, and FS, however, will require more than 50000 y cooling time because of their Nb and Mo contents. The RAFS, Mn-steel, Ti64 and V55 can be shallow-land wastes if the impurity level for Nb and Mo is dropped below 10 ppm.
Optimal Bidding Strategy for Renewable Microgrid with Active Network Management
Seung Wan Kim
2016-01-01
Full Text Available Active Network Management (ANM enables a microgrid to optimally dispatch the active/reactive power of its Renewable Distributed Generation (RDG and Battery Energy Storage System (BESS units in real time. Thus, a microgrid with high penetration of RDGs can handle their uncertainties and variabilities to achieve the stable operation using ANM. However, the actual power flow in the line connecting the main grid and microgrid may deviate significantly from the day-ahead bids if the bids are determined without consideration of the real-time adjustment through ANM, which will lead to a substantial imbalance cost. Therefore, this study proposes a formulation for obtaining an optimal bidding which reflects the change of power flow in the connecting line by real-time adjustment using ANM. The proposed formulation maximizes the expected profit of the microgrid considering various network and physical constraints. The effectiveness of the proposed bidding strategy is verified through the simulations with a 33-bus test microgrid. The simulation results show that the proposed bidding strategy improves the expected operating profit by reducing the imbalance cost to a greater degree compared to the basic bidding strategy without consideration of ANM.
A Network Model for Integrated Telecommunication Management Activities
SOIDRIDINE Moussa Moindze
2013-04-01
Full Text Available Technological developments in recent years have transformed the telecommunications environments in more complexes, distributed, heterogeneous and dynamic systems difficult to manage. Traditional management approaches show their limits to these new architectures. One possible approach to manage these environments is to develop novels models and open management systems. In this work, we proposed a new generic model with six layers for open systems development. We then proposed a flexible management system based on an open paradigm to the integrated management of next generation networks and services. We first studied the open source systems management to present out their strengths and weaknesses. The generic layered model that we propose allows integrating new management functions. And finally we have developed and implemented a system for remote configuration management of network devices
Application of the Management System for Facilities and Activities. Safety Guide
This publication provides guidance for following the requirements for management systems that integrate safety, health, security, quality assurance and environmental objectives. A successful management system ensures that nuclear safety matters are not dealt with in isolation but are considered within the context of all these objectives. The aim of this publication is to assist Member States to establish and implement effective management systems that coherently integrate all aspects of managing nuclear facilities and activities. Contents: 1. Introduction; 2. Management system; 3. Management responsibility; 4. Resource management; 5. Process implementation; 6. Measurement, assessment and improvement; Appendix I: Transition to an integrated management system; Appendix II: Activities in the document control process; Appendix III: Activities in the procurement process; Appendix IV: Performance of independent assessments; Annex I: Electronic document management system; Annex II: Media for record storage; Annex III: Record retention and storage; Glossary.
2013-04-22
..., eligibility criteria, management information systems, program staffing, treatment, testing, courtroom... National Highway Traffic Safety Administration Information Collection Activities: Submission for the Office of Management and Budget (OMB) Review; Request for Comment AGENCY: National Highway Traffic...
2013-06-03
... Agency Information Collection Activities; Submission to the Office of Management and Budget for Review... questionnaires. Wave 2 will contain technology and engineering literacy (TEL) and science ICT (interactive... Director, Information Collection Clearance Division, Privacy, Information and Records Management...
DESIGN AND APPLICATION OF QUEUE-BUFFER COMMUNICATION MODEL IN PNEUMATIC CONVEYING
Liping Zhang
2013-11-01
Full Text Available In order to communicate with a PLC (Programmable Logic Controller flexibly and freely, a data communication model based on the PLC's free port is designed. In the structure of the model, a distributed data communication environment is constructed by using Ethernet and serial adapters. In the communication algorithm, a method of queue-buffer for multi-threaded is used to improve the real-time of the control. This communication model has good scalability and portability because the realization of it is not restricted by the number of PLC slave stations and the type of operating system of the host computer. A corresponding communication algorithm is applied to data collection and devices monitoring for a pipe pneumatic conveying system. The practice shows that not only the stability and reliability of the model can meet the needs of automatic control but also the communication performance and efficiency of the model is outstanding.
The Value of Service Rate Flexibility in an M/M/1 Queue with Admission Control
Dimitrakopoulos, Yiannis
2012-01-01
We consider a single server queueing system with admission control and the possibility to switch dynamically between a low and a high service rate, and examine the benefit of this service rate flexibility. We formulate a discounted Markov Decision Process model for the problem of joint admission and service control, and show that the optimal policy has a threshold structure for both controls. Regarding the benefit due to flexibility, we show that it is increasing in system congestion, and that its effect on the admission policy is to increase the admission threshold. We also derive a simple approximate condition between the admission reward and the relative cost of service rate increase, so that the service rate flexibility is beneficial. We finally show that the results extend to the expected average reward case.
Bachmat, Eitan
2014-01-01
This monograph describes problems in the field of performance analysis, primarily the study of storage systems and the diverse mathematical techniques that are required for solving such problems. Topics covered include best practices for scheduling I/O requests to a disk drive, how this problem is related to airplane boarding, and how both problems can be modeled using space-time geometry. The author also explains how Riemann's proof of the analytic continuation and functional equation of the Riemann zeta function can be used to analyze express-line queues in a minimarket. Overall, the book reveals the surprising applicability of abstract mathematical ideas that are not usually associated with applied topics. Advanced undergraduate students or graduate students with an interest in the applications of mathematics will find this book a useful resource. It will also be of interest to professional mathematicians who want exposure to the surprising ways that theoretical mathematics may be applied to engineering pr...
Application of Estimation Techniques on Queue Lengths Estimation in Traffic Network
Pecherková, Pavla; Flídr, M.; Duník, J.
Londýn: IEEE, 2008 - (Comley, R.; Cheng, X.; Amavasai, B.; O'Grady, M.; Huyck, C.), s. 257-262 ISBN 978-1-4244-2914-1. [7th IEEE International conference on Cybernetic Intelligent System. London (GB), 09.09.2008-10.09.2008] R&D Projects: GA MŠk 1M0572 Institutional research plan: CEZ:AV0Z10750506 Keywords : traffic system model * stochastic systems * state estimation * Kalman filtering Subject RIV: BC - Control Systems Theory http://library.utia.cas.cz/separaty/2008/AS/pecherkova-application%20of%20estimation%20techniques%20on%20queue%20lengths%20estimation%20in%20traffic%20network.pdf
A Proof of Concept for Optimizing Task Parallelism by Locality Queues
Wittmann, Markus
2009-01-01
Task parallelism as employed by the OpenMP task construct, although ideal for tackling irregular problems or typical producer/consumer schemes, bears some potential for performance bottlenecks if locality of data access is important, which is typically the case for memory-bound code on ccNUMA systems. We present a programming technique which ameliorates adverse effects of dynamic task distribution by sorting tasks into locality queues, each of which is preferably processed by threads that belong to the same locality domain. Dynamic scheduling is fully preserved inside each domain, and is preferred over possible load imbalance even if non-local access is required. The effectiveness of the approach is demonstrated using a blocked six-point stencil solver as a toy model.
Mueen, Zeina; Ramli, Razamin; Zaibidi, Nerda Zura
2015-12-01
There are a number of real life systems that can be described as a queuing system, and this paper presents a queuing system model applied in a manufacturing system example. The queuing model considered is depicted in a fuzzy environment with retrial queues and unreliable server. The stability condition state of this model is investigated and the performance measurement is obtained by adopting the left and right method. The new approach adopted in this study merges the existing α-cut interval and nonlinear programming techniques and a numerical example was considered to explain the methodology of this technique. From the numerical example, the flexibility of the method was shown graphically showing the exact real mean value of customers in the system and also the expected waiting times.
Computing a constrained control policy for a single-server queueing system
Larsen, Christian
We consider a single-server queueing system designed to serve homogeneous jobs. The jobs arrive to the system after a Poisson process and all processing times are deterministic. There is a set-up cost for starting up production and a holding cost rate is incurred for each job present. Also, there...... is a service cost per job, which is a convex function of the service time. The control policy specifies when the server is on or off. It also specifies the state-dependent processing times. In order to avoid a very detailed control policy (which could be hard to implement) we will only allow the...... server to use n different processing times. Hence, we must subdivide the infinite state space into n disjoint sets and for each set decide which processing time to use. We show how to derive a mathematical expression for the long-run average cost per time unit. We also present an algorithm to find the...
Comparing the Overhead of Lock-based and Lock-free Implementations of Priority Queues
Passas, Stavros; Karlsson, Sven
2011-01-01
structures is to allow multiple cores to safely access the data structure. Traditionally, mutual exclusion using lock primitives has been used to avoid interference between cores. However, lock primitives cause a high synchronization overhead in situations with high contention. More recently, lock-free data...... structures have been proposed as a solution to decrease the synchronization overhead. Lock-free data structures are more complex than their lock-based counterparts. It is not evident if the benefits of lower synchronization overhead can offset the higher sequential execution time caused by the complexity. In...... this paper, we compare a lock-free implementation of a priority queue with a lock-based implementation. We perform experiments with processors of different generations and observe large performance differences for lock-free data structures depending on the processor generation. The lock...
Two-parameter sample path large deviations for infinite-server queues
Jose H. Blanchet
2014-09-01
Full Text Available Let Qλ(t,y be the number of people present at time t with y units of remaining service time in an infinite server system with arrival rate equal to λ>0. In the presence of a non-lattice renewal arrival process and assuming that the service times have a continuous distribution, we obtain a large deviations principle for Qλ( · /λ under the topology of uniform convergence on [0,T]×[0,∞. We illustrate our results by obtaining the most likely path, represented as a surface, to ruin in life insurance portfolios, and also we obtain the most likely surfaces to overflow in the setting of loss queues.
Orientation of sustainable management of chemical company with international activity
Valéria da Veiga Dias
2013-04-01
Full Text Available The search for new business possibilities, either through international activities and capture niche markets appear as a distinct trend among organizations that target growth. For this growing number of organizations intent on investing in new issues related to values such as citizenship, ethics and environmental concerns. There is the adoption of a more responsive to the community or even the acceptance of responsibility for the impacts of their production processes, inserting themselves in what was initially called the Social Responsibility within the business context and developed the concept of Elkington (1998 generated a discussion about a new movement that was called a sustainable paradigm. It was observed generally that sustainable management is still very close to supporting tools and not as part of the construction of corporate strategy although it is possible to realize that they seek a greater involvement in this direction when they start to review their strategies. This question can be perceived at different levels between the companies, but which shows the issue is the lack of direct indicators for investment and sustainable return. Sustainable management proved to be a source of opportunity for overseas business for the companies studied, as preparation for work with environmental legislation, global requirements, raw materials and environmentally friendly processes organizations prepared to market in the global sphere, and Brazil note that the innovative products for their production process and / or alternative raw material still do not get the spotlight. Acting in a sustainable manner enables the development of strategies agreed with conscious posture and changes in cultural terms in general, which can create new opportunities for those who can keep up with the global business scenario.
Risk management activities at the DOE Class A reactor facilities
The probabilistic risk assessment (PRA) and risk management group of the Association for Excellence in Reactor Operation (AERO) develops risk management initiatives and standards to improve operation and increase safety of the DOE Class A reactor facilities. Principal risk management applications that have been implemented at each facility are reviewed. The status of a program to develop guidelines for risk management programs at reactor facilities is presented
A Most Observable Retrial Queueing Model%几乎可视重试排队模型研究
邹宗保; 王建军; 邓贵仕
2013-01-01
通过采用拟生灭过程理论，研究了几乎可视重试排队模型。从经济学角度讨论了顾客、社会及垄断者的决策问题，并且得到了三者最优的门限策略。通过数值算例描绘了服务报酬对三个最优门限的影响。研究结果表明，顾客决策产生的门限最大，社会决策产生的门限次之，垄断者的门限最小。最后，从社会和管理者的角度出发，给出了相应的管理启示：在不同服务报酬下，通过收取相应的入场费迫使顾客的行为分别满足社会和管理者的最优门限。% This paper studies a most observable retrial queue via the quasi birth and death process theory .From the viewpoint of economics, we discuss decision-making problems of the customers , the society and the adminis-trator, and obtain their optimal threshold strategies .Then, we give some numerical examples to illustrate the effect of the service payments on the three optimal threshold strategies .The results showed that customer decision threshold is the biggest one, the social decision threshold the second biggest and the monopolist decision thresh-old the minimum one.Finally, we gave the corresponding management enlightenment from the points of view of the social and the manager: with different service payments, respective entrance fees are charged to force the behaviors of customers to satisfy the social decision threshold and the monopolist decision threshold .
Service Organizations: Customer Contact and Incentives of Knowledge Managers
Kirchmaier, Isadora
2014-01-01
We analyze the interdependence of human resource management and knowledge management. The service organization is modeled as a queueing network. The optimal number of workers in each division, the amount of customer contact and the wage for each manager is determined. We combine three features within the model. First, each manager may engage in customer contact. We show that although the fraction of time a worker is busy is increasing in rank of the manager, the customer task acceptance rate ...
Radioactive waste management activities of the OECD Nuclear Energy Agency
The objectives of the Organisation for Economic Co-operation and Development (OECD), which groups most of the developed countries of the world, are to promote high economic growth and a rising standard of living in Member countries while contributing to the economic development and the expansion of world trade on a multilateral basis. International co-operation in nuclear energy activities takes place through the OECD Nuclear Energy Agency (NEA) in which a total of 23 countries now participate: Australia, Canada, Japan, the United States, in addition to all the European Member countries of OECD. The Commission of the European Communities also takes part in the work of NEA. One of the primary objectives of the NEA is to promote co-operation between its Member governments on the safety and regulatory aspects of nuclear development. This is achieved by encouraging harmonization of governments' regulatory policies and practices in the nuclear field, with particular reference to the safety of nuclear installations, protection of many against ionizing radiations, radioactive waste management, and nuclear third party liability and insurance
Technical and economic impacts of active management on distribution network
With the deregulation of energy market and the appeal for environment protection, more and more distributed generation (DG) is embedded in the distribution network. However the approach of connecting DG in most cases is based on a so-called ''fit and forget'' policy and the capacity of DG is limited rigidly by distribution network operator (DNO) to avoid the negative effects of high level penetration. Therefore active management (AM) is put forward as an effective method to network reinforcement for the connection and operation of DG. In this paper, the concept and principle of AM are introduced, and several indices are proposed to evaluate both technical and economic impacts of AM on distribution network with DG. To simplify the simulation fuzzy C-means clustering (FCM) algorithm is introduced. The test results on a sample system represent that AM will lead to decrease of power generation of DG, but it can reduce energy losses and improve voltage profile effectively. Furthermore, AM will take great economic incentives to DG developer as well as DNO with reasonable policy. (author)
Risk management of offshore wind activities in North America
Smith, K.J. [Det Norske Veritas, Katy, TX (United States)
2010-07-01
Offshore wind energy projects present inherently different risks than onshore wind developments. However, many offshore industries are mature and have evolved risk management techniques and tools. This PowerPoint presentation discussed the techniques and tools that are being applied to European offshore wind projects in order to help the North American offshore wind industry incorporate the techniques into the development process. The Government of the Netherlands is currently using spatial analysis tools to determine the potential impact of wind power plants on shipping, fishing, and other competing activities. The tools are being used to identify areas with favourable conditions. Quantitative and qualitative risk evaluations are being used to determine complex issues related to harbour access and navigational safety, as the coastline of the Netherlands is among the busiest shipping lanes in the world. Navigation risk assessments are used to demonstrate the impacts of procedural changes on resulting structural and security risks. Datasets are compiled with geographic information system (GIS) maps. Marine accident risk calculation software (MARCS) is used to determine risks related to collisions as well as to quantify mitigation measures. Software tools have been developed to combine task and schedule elements with cost, performance, probability, and potential consequences. A project certification process was outlined, and conceptual design plans were presented. Details of the offshore wind safety joint industry project (JIP) were also provided. tabs., figs.
Petar-Pierre Matek
2015-09-01
Full Text Available This paper analyses Croatian mandatory pension funds’ investment returns during the 2005-2014 period using performance attribution methodology. Results from active investment management are compared to a long-term policy return. Such analysis is essential to shed light on the contribution of active portfolio management in the second pillar pension scheme. Evidence suggests that in the period analysed portfolio managers have added value through active management decisions. In addition, we determined the sources of portfolio return by breaking down active return into policy, tactical asset allocation and security selection effect.
Zhilin Qiao
2009-05-01
Full Text Available Activity based costing/management (ABC/M is an advanced method of cost calculation and enterprise management. It has been well developed and applied in many industries in western countries, especially in service industries. They received a lot from it. But at present, this kind of research is very scarce in China. This paper would do something about it. It analyzed one important service industry---insurance company’s business process with the theory of ABC/M. The cost of single variety was calculated in this new way. Activity’s increment and the validity were analyzed. Non-value-added activities in the course of insurance operation and management were discussed. At the end, some advices on how to improve the insurance company’s activity based management were proposed.