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Sample records for active queue management

  1. An Approach to Active Queue Management in Computer Network

    OpenAIRE

    Asimkiran Dandapat

    2016-01-01

    Active queue management is a key technique for reducing the packet drop rate in the internet. This packet dropping mechanism is used in a router to minimize congestion when the packets are dropped before queue gets full. In this paper a new framework of Active queue management namely MYRED is proposed. The goal of this new scheme is to improve the performance of AQM by keeping router queue length optimized. In RED packets are marked or dropped with a statistical probability before packet buff...

  2. Adaptive optimization for active queue management supporting TCP flows

    NARCIS (Netherlands)

    Baldi, S.; Kosmatopoulos, Elias B.; Pitsillides, Andreas; Lestas, Marios; Ioannou, Petros A.; Wan, Y.; Chiu, George; Johnson, Katie; Abramovitch, Danny

    2016-01-01

    An adaptive decentralized strategy for active queue management of TCP flows over communication networks is presented. The proposed strategy solves locally, at each link, an optimal control problem, minimizing a cost composed of residual capacity and buffer queue size. The solution of the optimal

  3. SAM: Support Vector Machine Based Active Queue Management

    International Nuclear Information System (INIS)

    Shah, M.S.

    2014-01-01

    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)

  4. Performance study of Active Queue Management methods: Adaptive GRED, REDD, and GRED-Linear analytical model

    Directory of Open Access Journals (Sweden)

    Hussein Abdel-jaber

    2015-10-01

    Full Text Available Congestion control is one of the hot research topics that helps maintain the performance of computer networks. This paper compares three Active Queue Management (AQM methods, namely, Adaptive Gentle Random Early Detection (Adaptive GRED, Random Early Dynamic Detection (REDD, and GRED Linear analytical model with respect to different performance measures. Adaptive GRED and REDD are implemented based on simulation, whereas GRED Linear is implemented as a discrete-time analytical model. Several performance measures are used to evaluate the effectiveness of the compared methods mainly mean queue length, throughput, average queueing delay, overflow packet loss probability, and packet dropping probability. The ultimate aim is to identify the method that offers the highest satisfactory performance in non-congestion or congestion scenarios. The first comparison results that are based on different packet arrival probability values show that GRED Linear provides better mean queue length; average queueing delay and packet overflow probability than Adaptive GRED and REDD methods in the presence of congestion. Further and using the same evaluation measures, Adaptive GRED offers a more satisfactory performance than REDD when heavy congestion is present. When the finite capacity of queue values varies the GRED Linear model provides the highest satisfactory performance with reference to mean queue length and average queueing delay and all the compared methods provide similar throughput performance. However, when the finite capacity value is large, the compared methods have similar results in regard to probabilities of both packet overflowing and packet dropping.

  5. A novel fair active queue management algorithm based on traffic delay jitter

    Science.gov (United States)

    Wang, Xue-Shun; Yu, Shao-Hua; Dai, Jin-You; Luo, Ting

    2009-11-01

    In order to guarantee the quantity of data traffic delivered in the network, congestion control strategy is adopted. According to the study of many active queue management (AQM) algorithms, this paper proposes a novel active queue management algorithm named JFED. JFED can stabilize queue length at a desirable level by adjusting output traffic rate and adopting a reasonable calculation of packet drop probability based on buffer queue length and traffic jitter; and it support burst packet traffic through the packet delay jitter, so that it can traffic flow medium data. JFED impose effective punishment upon non-responsible flow with a full stateless method. To verify the performance of JFED, it is implemented in NS2 and is compared with RED and CHOKe with respect to different performance metrics. Simulation results show that the proposed JFED algorithm outperforms RED and CHOKe in stabilizing instantaneous queue length and in fairness. It is also shown that JFED enables the link capacity to be fully utilized by stabilizing the queue length at a desirable level, while not incurring excessive packet loss ratio.

  6. Model Integrating Fuzzy Argument with Neural Network Enhancing the Performance of Active Queue Management

    Directory of Open Access Journals (Sweden)

    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.

  7. Active Queue Management in TCP Networks Based on Fuzzy-Pid Controller

    Directory of Open Access Journals (Sweden)

    Hossein ASHTIANI

    2012-01-01

    Full Text Available We introduce a novel and robust active queue management (AQM scheme based on a fuzzy controller, called hybrid fuzzy-PID controller. In the TCP network, AQM is important to regulate the queue length by passing or dropping the packets at the intermediate routers. RED, PI, and PID algorithms have been used for AQM. But these algorithms show weaknesses in the detection and control of congestion under dynamically changing network situations. In this paper a novel Fuzzy-based proportional-integral derivative (PID controller, which acts as an active queue manager (AQM for Internet routers, is proposed. These controllers are used to reduce packet loss and improve network utilization in TCP/IP networks. A new hybrid controller is proposed and compared with traditional RED based controller. Simulations are carried out to demonstrate the effectiveness of the proposed method and show that, the new hybrid fuzzy PID controller provides better performance than random early detection (RED and PID controllers

  8. A GA-based PID active queue management control design for TCP/IP networks

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, H-H; Chen, C-K; Liao, T-L [Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan (China); Yan, J-J [Department of Computer and Communication, Shu-Te University, Kaohsiung 824, Taiwan (China)], E-mail: tlliao@mail.ncku.edu.tw

    2008-02-15

    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.

  9. A GA-based PID active queue management control design for TCP/IP networks

    International Nuclear Information System (INIS)

    Kuo, H-H; Chen, C-K; Liao, T-L; Yan, J-J

    2008-01-01

    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

  10. Design and analysis of a model predictive controller for active queue management.

    Science.gov (United States)

    Wang, Ping; Chen, Hong; Yang, Xiaoping; Ma, Yan

    2012-01-01

    Model predictive (MP) control as a novel active queue management (AQM) algorithm in dynamic computer networks is proposed. According to the predicted future queue length in the data buffer, early packets at the router are dropped reasonably by the MPAQM controller so that the queue length reaches the desired value with minimal tracking error. The drop probability is obtained by optimizing the network performance. Further, randomized algorithms are applied to analyze the robustness of MPAQM successfully, and also to provide the stability domain of systems with uncertain network parameters. The performances of MPAQM are evaluated through a series of simulations in NS2. The simulation results show that the MPAQM algorithm outperforms RED, PI, and REM algorithms in terms of stability, disturbance rejection, and robustness. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

  11. Adaptive Mean Queue Size and Its Rate of Change: Queue Management with Random Dropping

    OpenAIRE

    Karmeshu; Patel, Sanjeev; Bhatnagar, Shalabh

    2016-01-01

    The Random early detection (RED) active queue management (AQM) scheme uses the average queue size to calculate the dropping probability in terms of minimum and maximum thresholds. The effect of heavy load enhances the frequency of crossing the maximum threshold value resulting in frequent dropping of the packets. An adaptive queue management with random dropping (AQMRD) algorithm is proposed which incorporates information not just about the average queue size but also the rate of change of th...

  12. An Active Queue Management for QoS Guarantee of the High Priority Service Class

    Science.gov (United States)

    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.

  13. Multicast Services of QoS-Aware Active Queue Management over IP Multimedia Applications

    Science.gov (United States)

    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.

  14. Active queue management controller design for TCP communication networks: Variable structure control approach

    International Nuclear Information System (INIS)

    Chen, C.-K.; Liao, T.-L.; Yan, J.-J.

    2009-01-01

    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.

  15. Active queue management controller design for TCP communication networks: Variable structure control approach

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Predictive functional control for active queue management in congested TCP/IP networks.

    Science.gov (United States)

    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.

  17. A robust fractional-order PID controller design based on active queue management for TCP network

    Science.gov (United States)

    Hamidian, Hamideh; Beheshti, Mohammad T. H.

    2018-01-01

    In this paper, a robust fractional-order controller is designed to control the congestion in transmission control protocol (TCP) networks with time-varying parameters. Fractional controllers can increase the stability and robustness. Regardless of advantages of fractional controllers, they are still not common in congestion control in TCP networks. The network parameters are time-varying, so the robust stability is important in congestion controller design. Therefore, we focused on the robust controller design. The fractional PID controller is developed based on active queue management (AQM). D-partition technique is used. The most important property of designed controller is the robustness to the time-varying parameters of the TCP network. The vertex quasi-polynomials of the closed-loop characteristic equation are obtained, and the stability boundaries are calculated for each vertex quasi-polynomial. The intersection of all stability regions is insensitive to network parameter variations, and results in robust stability of TCP/AQM system. NS-2 simulations show that the proposed algorithm provides a stable queue length. Moreover, simulations show smaller oscillations of the queue length and less packet drop probability for FPID compared to PI and PID controllers. We can conclude from NS-2 simulations that the average packet loss probability variations are negligible when the network parameters change.

  18. ANALYTICAL CHARACTERIZATION OF WLANS FOR QUALITY-OF-SERVICE WITH ACTIVE QUEUE MANAGEMENT

    Directory of Open Access Journals (Sweden)

    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.

  19. QoS-Aware Active Queue Management for Multimedia Services over the Internet

    Directory of Open Access Journals (Sweden)

    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.

  20. Survival of the Fittest: An Active Queue Management Technique for Noisy Packet Flows

    Directory of Open Access Journals (Sweden)

    Shirish S. Karande

    2007-01-01

    Full Text Available We present a novel active queue management (AQM technique to demonstrate the efficacy of practically harnessing the predictive utility of SSR indications for improved video communication. We consider a network within which corrupted packets are relayed over multiple hops, but a certain percentage of packets needs to be dropped at an intermediate node due to congestion. We propose an AQM technique, survival of the fittest (SOTF, to be employed at the relay node, within which we use packet state information, available from SSR indications and checksums, to drop packets with the highest corruption levels. On the basis of actual 802.11b measurements we show that such a side information (SI aware processing within the network can provide significant performance benefits over an SI-unaware scheme, random queue management (RQM, which is forced to randomly discard packets. With trace-based simulations, we show the utility of the proposed AQM technique in improving the error recovery performance of cross-layer FEC schemes. Finally, with the help of H.264-based video simulations these improvements are shown to translate into a significant improvement in video quality.

  1. Design of Active Queue Management for Robust Control on Access Router for Heterogeneous Networks

    Directory of Open Access Journals (Sweden)

    Åhlund Christer

    2011-01-01

    Full Text Available The Internet architecture is a packet switching technology that allows dynamic sharing of bandwidth among different flows with in an IP network. Packets are stored and forwarded from one node to the next until reaching their destination. Major issues in this integration are congestion control and how to meet different quality of service requirements associated with various services. In other words streaming media quality degrades with increased packet delay and jitter caused by network congestion. To mitigate the impact of network congestion, various techniques have been used to improve multimedia quality and one of those techniques is Active Queue Management (AQM. Access routers require a buffer to hold packets during times of congestion. A large buffer can absorb the bursty arrivals, and this tends to increase the link utilizations but results in higher queuing delays. Traffic burstiness has a considerable negative impact on network performance. AQM is now considered an effective congestion control mechanism for enhancing transport protocol performance over wireless links. In order to have good link utilization, it is necessary for queues to adapt to varying traffic loads. This paper considers a particular scheme which is called Adaptive AQM (AAQM and studies its performance in the presence of feedback delays and its ability to maintain a small queue length as well as its robustness in the presence of traffic burstiness. The paper also presents a method based on the well-known Markov Modulated Poisson Process (MPP to capture traffic burstiness and buffer occupancy. To demonstrate the generality of the presented method, an analytic model is described and verified by extensive simulations of different adaptive AQM algorithms. The analysis and simulations show that AAQM outperforms the other AQMs with respect to responsiveness and robustness.

  2. STUDY THE EFFECTIVENESS APPLICATIONS OF FUZZY CONTROLLER WITH TWO ENTRANCES IN THE SYSTEM OF ACTIVE QUEUE MANAGEMENT THE PACKETS IN TCP/IP NETWORKS

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    O. V. Nevdachyna

    2016-01-01

    Full Text Available The paper presents an approach to solving the overloading problem in TCP/IP networks. Offered fuzzy controller with two inputs for system of active queue management packages in TCP/IP networks, and investigated its use in these systems with a random change of traffic load. Proposed controller has two inputs, one of which is the value of the difference between the current queue length and the second – the difference between the current level of usage of the buffer. The output of the fuzzy controller calculates the probability of discarding packet.Mathematical model system of active queue management that is studied is presented in an interactive MATLAB system, in wherein also is demonstrated the processes occurring in the system with a random change of traffic load. The research results show that the AQM-system with fuzzy controller with two entrances stable enough maintains the desired current length the queue for sufficiently small values of the probability of dropping/marking packets (at acceptable size of queue q0= 200 packets, the average probability of dropping / marking is not more than 3,5×10–3 or less 0,35% packets is discarded or marked from the total number of incoming packets. The results obtained will help improve the efficiency of the functioning and operation of TCP / IP networks by increasing data transmission quality. this happens due introduction of the proposed controller at the design of new, more efficient routers for networks to minimize the delay of information.

  3. The WorkQueue project - a task queue for the CMS workload management system

    Science.gov (United States)

    Ryu, S.; Wakefield, S.

    2012-12-01

    We present the development and first experience of a new component (termed WorkQueue) in the CMS workload management system. This component provides a link between a global request system (Request Manager) and agents (WMAgents) which process requests at compute and storage resources (known as sites). These requests typically consist of creation or processing of a data sample (possibly terabytes in size). Unlike the standard concept of a task queue, the WorkQueue does not contain fully resolved work units (known typically as jobs in HEP). This would require the WorkQueue to run computationally heavy algorithms that are better suited to run in the WMAgents. Instead the request specifies an algorithm that the WorkQueue uses to split the request into reasonable size chunks (known as elements). An advantage of performing lazy evaluation of an element is that expanding datasets can be accommodated by having job details resolved as late as possible. The WorkQueue architecture consists of a global WorkQueue which obtains requests from the request system, expands them and forms an element ordering based on the request priority. Each WMAgent contains a local WorkQueue which buffers work close to the agent, this overcomes temporary unavailability of the global WorkQueue and reduces latency for an agent to begin processing. Elements are pulled from the global WorkQueue to the local WorkQueue and into the WMAgent based on the estimate of the amount of work within the element and the resources available to the agent. WorkQueue is based on CouchDB, a document oriented NoSQL database. The WorkQueue uses the features of CouchDB (map/reduce views and bi-directional replication between distributed instances) to provide a scalable distributed system for managing large queues of work. The project described here represents an improvement over the old approach to workload management in CMS which involved individual operators feeding requests into agents. This new approach allows for a

  4. The WorkQueue project - a task queue for the CMS workload management system

    International Nuclear Information System (INIS)

    Ryu, S; Wakefield, S

    2012-01-01

    We present the development and first experience of a new component (termed WorkQueue) in the CMS workload management system. This component provides a link between a global request system (Request Manager) and agents (WMAgents) which process requests at compute and storage resources (known as sites). These requests typically consist of creation or processing of a data sample (possibly terabytes in size). Unlike the standard concept of a task queue, the WorkQueue does not contain fully resolved work units (known typically as jobs in HEP). This would require the WorkQueue to run computationally heavy algorithms that are better suited to run in the WMAgents. Instead the request specifies an algorithm that the WorkQueue uses to split the request into reasonable size chunks (known as elements). An advantage of performing lazy evaluation of an element is that expanding datasets can be accommodated by having job details resolved as late as possible. The WorkQueue architecture consists of a global WorkQueue which obtains requests from the request system, expands them and forms an element ordering based on the request priority. Each WMAgent contains a local WorkQueue which buffers work close to the agent, this overcomes temporary unavailability of the global WorkQueue and reduces latency for an agent to begin processing. Elements are pulled from the global WorkQueue to the local WorkQueue and into the WMAgent based on the estimate of the amount of work within the element and the resources available to the agent. WorkQueue is based on CouchDB, a document oriented NoSQL database. The WorkQueue uses the features of CouchDB (map/reduce views and bi-directional replication between distributed instances) to provide a scalable distributed system for managing large queues of work. The project described here represents an improvement over the old approach to workload management in CMS which involved individual operators feeding requests into agents. This new approach allows for a

  5. The WorkQueue project: A task queue for the CMS workload management system

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, S. [Fermilab; Wakefield, Stuart [Imperial Coll., London

    2012-01-01

    We present the development and first experience of a new component (termed WorkQueue) in the CMS workload management system. This component provides a link between a global request system (Request Manager) and agents (WMAgents) which process requests at compute and storage resources (known as sites). These requests typically consist of creation or processing of a data sample (possibly terabytes in size). Unlike the standard concept of a task queue, the WorkQueue does not contain fully resolved work units (known typically as jobs in HEP). This would require the WorkQueue to run computationally heavy algorithms that are better suited to run in the WMAgents. Instead the request specifies an algorithm that the WorkQueue uses to split the request into reasonable size chunks (known as elements). An advantage of performing lazy evaluation of an element is that expanding datasets can be accommodated by having job details resolved as late as possible. The WorkQueue architecture consists of a global WorkQueue which obtains requests from the request system, expands them and forms an element ordering based on the request priority. Each WMAgent contains a local WorkQueue which buffers work close to the agent, this overcomes temporary unavailability of the global WorkQueue and reduces latency for an agent to begin processing. Elements are pulled from the global WorkQueue to the local WorkQueue and into the WMAgent based on the estimate of the amount of work within the element and the resources available to the agent. WorkQueue is based on CouchDB, a document oriented NoSQL database. The WorkQueue uses the features of CouchDB (map/reduce views and bi-directional replication between distributed instances) to provide a scalable distributed system for managing large queues of work. The project described here represents an improvement over the old approach to workload management in CMS which involved individual operators feeding requests into agents. This new approach allows for a

  6. A robust and high-performance queue management controller for large round trip time networks

    Science.gov (United States)

    Khoshnevisan, Ladan; Salmasi, Farzad R.

    2016-05-01

    Congestion management for transmission control protocol is of utmost importance to prevent packet loss within a network. This necessitates strategies for active queue management. The most applied active queue management strategies have their inherent disadvantages which lead to suboptimal performance and even instability in the case of large round trip time and/or external disturbance. This paper presents an internal model control robust queue management scheme with two degrees of freedom in order to restrict the undesired effects of large and small round trip time and parameter variations in the queue management. Conventional approaches such as proportional integral and random early detection procedures lead to unstable behaviour due to large delay. Moreover, internal model control-Smith scheme suffers from large oscillations due to the large round trip time. On the other hand, other schemes such as internal model control-proportional integral and derivative show excessive sluggish performance for small round trip time values. To overcome these shortcomings, we introduce a system entailing two individual controllers for queue management and disturbance rejection, simultaneously. Simulation results based on Matlab/Simulink and also Network Simulator 2 (NS2) demonstrate the effectiveness of the procedure and verify the analytical approach.

  7. Comparison of TEAR and TFRC throughput for Drop tail and RED Queue Management Techniques

    Directory of Open Access Journals (Sweden)

    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.

  8. The congestion control algorithm based on queue management of each node in mobile ad hoc networks

    Science.gov (United States)

    Wei, Yifei; Chang, Lin; Wang, Yali; Wang, Gaoping

    2016-12-01

    This paper proposes an active queue management mechanism, considering the node's own ability and its importance in the network to set the queue threshold. As the network load increases, local congestion of mobile ad hoc network may lead to network performance degradation, hot node's energy consumption increase even failure. If small energy nodes congested because of forwarding data packets, then when it is used as the source node will cause a lot of packet loss. This paper proposes an active queue management mechanism, considering the node's own ability and its importance in the network to set the queue threshold. Controlling nodes buffer queue in different levels of congestion area probability by adjusting the upper limits and lower limits, thus nodes can adjust responsibility of forwarding data packets according to their own situation. The proposed algorithm will slow down the send rate hop by hop along the data package transmission direction from congestion node to source node so that to prevent further congestion from the source node. The simulation results show that, the algorithm can better play the data forwarding ability of strong nodes, protect the weak nodes, can effectively alleviate the network congestion situation.

  9. Buffer Management of Multi-Queue QoS Switches with Class Segregation

    OpenAIRE

    Itoh, Toshiya; Yoshimoto, Seiji

    2013-01-01

    In this paper, we focus on buffer management of multi-queue QoS switches in which packets of different values are segregated in different queues. Our model consists of $m$ queues and $m$ packet values $0 < v_{1} < v_{2} < ... < v_{m}$. Recently, Al-Bawani and Souza [IPL 113(4), pp.145-150, 2013] presented an online algorithm GREEDY for buffer management of multi-queue QoS switches with class segregation and showed thatif $m$ queues have the same size, then the competitive ratio of GREEDY is $...

  10. Adaptive Queue Management with Restraint on Non-Responsive Flows

    Directory of Open Access Journals (Sweden)

    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.

  11. Infinite Queue Management via Cascade Control for Industrial Routers in Smart Grid IP Networks

    OpenAIRE

    Kim, Ku-Hwan; To, Hoang-Linh; Hwang, Won-Joo; Lee, Jung-Tae

    2016-01-01

    Smart grid applications experience an extremely wide range of communication delay. Data flows of those applications are normally aggregated at industrial network routers in substations, form infinite (long) queues termed bufferbloat issue, and might damage the operation of transmission control protocol. The default queue management scheme, DropTail, in such routers just drops packets if queue is full while the others in literature are mostly based on one-loop feedback control where an optimal...

  12. Apparatus and method for managing digital resources by passing digital resource tokens between queues

    Science.gov (United States)

    Crawford, H.J.; Lindenstruth, V.

    1999-06-29

    A method of managing digital resources of a digital system includes the step of reserving token values for certain digital resources in the digital system. A selected token value in a free-buffer-queue is then matched to an incoming digital resource request. The selected token value is then moved to a valid-request-queue. The selected token is subsequently removed from the valid-request-queue to allow a digital agent in the digital system to process the incoming digital resource request associated with the selected token. Thereafter, the selected token is returned to the free-buffer-queue. 6 figs.

  13. The evaluation of a formalized queue management system for coronary angiography waiting lists.

    Science.gov (United States)

    Alter, D A; Newman, Alice M; Cohen, Eric A; Sykora, Kathy; Tu, Jack V

    2005-11-01

    Lengthy waiting lists for coronary angiography have been described in many health care systems worldwide. The extent to which formal queue management systems may improve the prioritization and survival of patients in the angiography queue is unknown. To prospectively evaluate the performance of a formal queue management system for patients awaiting coronary angiography in Ontario. The coronary angiography urgency scale, a formal queue management system developed in 1993 using a modified Delphi panel, allocates recommended maximum waiting times (RMWTs) in accordance with clinical necessity. By using a provincial clinical registry, 35,617 consecutive patients referred into the coronary angiography queue between April 1, 2001, and March 31, 2002, were prospectively tracked. Cox proportional hazards models were used to examined mortality risk across urgency after adjusting for additional clinical and comorbid factors. Good agreement was determined in urgency ratings between scores from the coronary angiography urgency scale and implicit physician judgement, which was obtained independently at the time of the index referral (weighted kappa = 0.49). The overall mortality in the queue was 0.3% (0.47%, 0.26% and 0.13% for urgent, semiurgent and elective patients, respectively). Urgency, as specified by the coronary angiography urgency scale, was the strongest predictor of death in the queue (Pqueue management system may decrease mortality in the coronary angiography queue. The authors recommend its implementation in health care systems where patients experience excessive waiting time delays for coronary angiography.

  14. Priority Queue Based Reactive Buffer Management Policy for Delay Tolerant Network under City Based Environments.

    Directory of Open Access Journals (Sweden)

    Qaisar Ayub

    Full Text Available Delay Tolerant Network (DTN multi-copy routing protocols are privileged to create and transmit multiple copies of each message that causes congestion and some messages are dropped. This process is known as reactive drop because messages were dropped re-actively to overcome buffer overflows. The existing reactive buffer management policies apply a single metric to drop source, relay and destine messages. Hereby, selection to drop a message is dubious because each message as source, relay or destine may have consumed dissimilar magnitude of network resources. Similarly, DTN has included time to live (ttl parameter which defines lifetime of message. Hence, when ttl expires then message is automatically destroyed from relay nodes. However, time-to-live (ttl is not applicable on messages reached at their destinations. Moreover, nodes keep replicating messages till ttl expires even-though large number of messages has already been dispersed. In this paper, we have proposed Priority Queue Based Reactive Buffer Management Policy (PQB-R for DTN under City Based Environments. The PQB-R classifies buffered messages into source, relay and destine queues. Moreover, separate drop metric has been applied on individual queue. The experiment results prove that proposed PQB-R has reduced number of messages transmissions, message drop and increases delivery ratio.

  15. Priority Queue Based Reactive Buffer Management Policy for Delay Tolerant Network under City Based Environments.

    Science.gov (United States)

    Ayub, Qaisar; Ngadi, Asri; Rashid, Sulma; Habib, Hafiz Adnan

    2018-01-01

    Delay Tolerant Network (DTN) multi-copy routing protocols are privileged to create and transmit multiple copies of each message that causes congestion and some messages are dropped. This process is known as reactive drop because messages were dropped re-actively to overcome buffer overflows. The existing reactive buffer management policies apply a single metric to drop source, relay and destine messages. Hereby, selection to drop a message is dubious because each message as source, relay or destine may have consumed dissimilar magnitude of network resources. Similarly, DTN has included time to live (ttl) parameter which defines lifetime of message. Hence, when ttl expires then message is automatically destroyed from relay nodes. However, time-to-live (ttl) is not applicable on messages reached at their destinations. Moreover, nodes keep replicating messages till ttl expires even-though large number of messages has already been dispersed. In this paper, we have proposed Priority Queue Based Reactive Buffer Management Policy (PQB-R) for DTN under City Based Environments. The PQB-R classifies buffered messages into source, relay and destine queues. Moreover, separate drop metric has been applied on individual queue. The experiment results prove that proposed PQB-R has reduced number of messages transmissions, message drop and increases delivery ratio.

  16. Infinite Queue Management via Cascade Control for Industrial Routers in Smart Grid IP Networks

    Directory of Open Access Journals (Sweden)

    Ku-Hwan Kim

    2016-01-01

    Full Text Available Smart grid applications experience an extremely wide range of communication delay. Data flows of those applications are normally aggregated at industrial network routers in substations, form infinite (long queues termed bufferbloat issue, and might damage the operation of transmission control protocol. The default queue management scheme, DropTail, in such routers just drops packets if queue is full while the others in literature are mostly based on one-loop feedback control where an optimal point of performance between queue length and drop rate is limited. In this paper, we study the problem of managing a long queue of industrial router at substation under heterogeneous smart grid networks. Specifically, we propose an enqueue-dequeue dropping cascade control using a two-loop design method to control both window size and queue length. Moreover, our proposal can be easily implemented into router firmware with provided discrete expressions. Finally, our simulation results are presented to validate the possible benefits that can be gained from cascade control and compare the existing queue management methods as well.

  17. A Parallel Virtual Queue Structure for Active Queue Management

    National Research Council Canada - National Science Library

    Jou, Jia-Shiang; Baras, John S

    2003-01-01

    .... However, a great portion of Internet traffic is shortlife web and UDP traffic. Most web traffic has a small file size and its TCP session is mainly operated in the slow start phase with a small congestion window size...

  18. Optimal Control for Bufferbloat Queue Management Using Indirect Method with Parametric Optimization

    Directory of Open Access Journals (Sweden)

    Amr Radwan

    2016-01-01

    Full Text Available Because memory buffers become larger and cheaper, they have been put into network devices to reduce the number of loss packets and improve network performance. However, the consequences of large buffers are long queues at network bottlenecks and throughput saturation, which has been recently noticed in research community as bufferbloat phenomenon. To address such issues, in this article, we design a forward-backward optimal control queue algorithm based on an indirect approach with parametric optimization. The cost function which we want to minimize represents a trade-off between queue length and packet loss rate performance. Through the integration of an indirect approach with parametric optimization, our proposal has advantages of scalability and accuracy compared to direct approaches, while still maintaining good throughput and shorter queue length than several existing queue management algorithms. All numerical analysis, simulation in ns-2, and experiment results are provided to solidify the efficiency of our proposal. In detailed comparisons to other conventional algorithms, the proposed procedure can run much faster than direct collocation methods while maintaining a desired short queue (≈40 packets in simulation and 80 (ms in experiment test.

  19. Queue Management Practices of Quick ServiceRestaurants (QSR in Lipa City, Philippines

    Directory of Open Access Journals (Sweden)

    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.

  20. Group-Server Queues

    OpenAIRE

    Li, Quan-Lin; Ma, Jing-Yu; Xie, Mingzhou; Xia, Li

    2017-01-01

    By analyzing energy-efficient management of data centers, this paper proposes and develops a class of interesting {\\it Group-Server Queues}, and establishes two representative group-server queues through loss networks and impatient customers, respectively. Furthermore, such two group-server queues are given model descriptions and necessary interpretation. Also, simple mathematical discussion is provided, and simulations are made to study the expected queue lengths, the expected sojourn times ...

  1. Transient probabilities for queues with applications to hospital waiting list management.

    Science.gov (United States)

    Joy, Mark; Jones, Simon

    2005-08-01

    In this paper we study queuing systems within the NHS. Recently imposed government performance targets lead NHS executives to investigate and instigate alternative management strategies, thereby imposing structural changes on the queues. Under such circumstances, it is most unlikely that such systems are in equilibrium. It is crucial, in our opinion, to recognise this state of affairs in order to make a balanced assessment of the role of queue management in the modern NHS. From a mathematical perspective it should be emphasised that measures of the state of a queue based upon the assumption of statistical equilibrium (a pervasive methodology in the study of queues) are simply wrong in the above scenario. To base strategic decisions around such ideas is therefore highly questionable and it is one of the purposes of this paper to offer alternatives: we present some (recent) research whose results generate performance measures and measures of risk, for example, of waiting-times growing unacceptably large; we emphasise that these results concern the transient behaviour of the queueing model-there is no asssumption of statistical equilibrium. We also demonstrate that our results are computationally tractable.

  2. Research on elastic resource management for multi-queue under cloud computing environment

    Science.gov (United States)

    CHENG, Zhenjing; LI, Haibo; HUANG, Qiulan; Cheng, Yaodong; CHEN, Gang

    2017-10-01

    As a new approach to manage computing resource, virtualization technology is more and more widely applied in the high-energy physics field. A virtual computing cluster based on Openstack was built at IHEP, using HTCondor as the job queue management system. In a traditional static cluster, a fixed number of virtual machines are pre-allocated to the job queue of different experiments. However this method cannot be well adapted to the volatility of computing resource requirements. To solve this problem, an elastic computing resource management system under cloud computing environment has been designed. This system performs unified management of virtual computing nodes on the basis of job queue in HTCondor based on dual resource thresholds as well as the quota service. A two-stage pool is designed to improve the efficiency of resource pool expansion. This paper will present several use cases of the elastic resource management system in IHEPCloud. The practical run shows virtual computing resource dynamically expanded or shrunk while computing requirements change. Additionally, the CPU utilization ratio of computing resource was significantly increased when compared with traditional resource management. The system also has good performance when there are multiple condor schedulers and multiple job queues.

  3. A queueing model of pilot decision making in a multi-task flight management situation

    Science.gov (United States)

    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.

  4. DROP TAIL AND RED QUEUE MANAGEMENT WITH SMALL BUFFERS:STABILITY AND HOPF BIFURCATION

    Directory of Open Access Journals (Sweden)

    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.

  5. BOB-RED queue management for IEEE 802.15.4 wireless sensor networks

    Directory of Open Access Journals (Sweden)

    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.

  6. Analysing patient queue system in an imaging department: a step toward total quality management

    International Nuclear Information System (INIS)

    Kumar, Pratik; Pandey, A.K.

    2008-01-01

    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

  7. Method, apparatus and system for managing queue operations of a test bench environment

    Science.gov (United States)

    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.

  8. An energy-efficient MAC protocol using dynamic queue management for delay-tolerant mobile sensor networks.

    Science.gov (United States)

    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.

  9. Implementation of shared queues

    OpenAIRE

    Motte, Nicolas

    2012-01-01

    The transactional framework used to develop Amadeus C++ applications is based on a mechanism of queues to manage the message exchanges between components. These structures are protected from concurrent access thanks to synchronization services provided by Linux. But theses services have a cost in term of performance and they bound the volume of messages transmitted by these queues. In a first step, I have to investigate on the state-of-the-art in term of management algorithms o...

  10. Queueing theoretic analysis of labor and delivery : Understanding management styles and C-section rates.

    Science.gov (United States)

    Gombolay, Matthew; Golen, Toni; Shah, Neel; Shah, Julie

    2017-09-04

    Childbirth is a complex clinical service requiring the coordinated support of highly trained healthcare professionals as well as management of a finite set of critical resources (such as staff and beds) to provide safe care. The mode of delivery (vaginal delivery or cesarean section) has a significant effect on labor and delivery resource needs. Further, resource management decisions may impact the amount of time a physician or nurse is able to spend with any given patient. In this work, we employ queueing theory to model one year of transactional patient information at a tertiary care center in Boston, Massachusetts. First, we observe that the M/G/∞ model effectively predicts patient flow in an obstetrics department. This model captures the dynamics of labor and delivery where patients arrive randomly during the day, the duration of their stay is based on their individual acuity, and their labor progresses at some rate irrespective of whether they are given a bed. Second, using our queueing theoretic model, we show that reducing the rate of cesarean section - a current quality improvement goal in American obstetrics - may have important consequences with regard to the resource needs of a hospital. We also estimate the potential financial impact of these resource needs from the hospital perspective. Third, we report that application of our model to an analysis of potential patient coverage strategies supports the adoption of team-based care, in which attending physicians share responsibilities for patients.

  11. Management of demand in the NHS, including the effects of queues and pensioners.

    Science.gov (United States)

    Groocock, J

    1999-01-01

    Discusses the methods used in the NHS to bring demand into balance with supply. People with minor illnesses try self-treatments and alternative medicine. Systematic programs to identify ill people are applied to only a few illnesses. Waiting lists for elective surgery cause some richer people to take their demand to private hospitals. An analysis of such waiting lists shows that, other than this, queues are not a method of rationing but are just the effect of bad management of the actual methods, which are then discussed. The same methods are used to ration access to specialist physicians. Providing extra resources would eliminate queues only if another condition was satisfied. It is argued that providing fully adequate medical care for patients of working age, although expensive, might produce a net economic gain, whereas all care for pensioners, including medical care, gives a net economic loss. Therefore it may not be sensible for people to have inadequate medical care for the first 65 years of their lives just because it is economically impracticable for them to have fully adequate medical care when they are pensioners.

  12. Time Is Not on Our Side: How Radiology Practices Should Manage Customer Queues.

    Science.gov (United States)

    Loving, Vilert A; Ellis, Richard L; Rippee, Robert; Steele, Joseph R; Schomer, Donald F; Shoemaker, Stowe

    2017-11-01

    As health care shifts toward patient-centered care, wait times have received increasing scrutiny as an important metric for patient satisfaction. Long queues form when radiology practices inefficiently service their customers, leading to customer dissatisfaction and a lower perception of value. This article describes a four-step framework for radiology practices to resolve problematic queues: (1) analyze factors contributing to queue formation; (2) improve processes to reduce service times; (3) reduce variability; (4) address the psychology of queues. Copyright © 2017 American College of Radiology. Published by Elsevier Inc. All rights reserved.

  13. WQM: An Aggregation-aware Queue Management Scheme for IEEE 802.11n based Networks

    KAUST Repository

    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.

  14. Queueing for healthcare.

    Science.gov (United States)

    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.

  15. Flow time analysis of load management late arrival discrete time queueing system with dual service rate using hypo geometrical distribution

    International Nuclear Information System (INIS)

    Shah, S.A.; Shah, W.; Shaikh, F.K.

    2012-01-01

    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)

  16. An Energy-Efficient MAC Protocol Using Dynamic Queue Management for Delay-Tolerant Mobile Sensor Networks

    Directory of Open Access Journals (Sweden)

    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.

  17. Buffer management in wireless full-duplex systems

    KAUST Repository

    Bouacida, Nader; Showail, Ahmad; Shihada, Basem

    2015-01-01

    , 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

  18. Active Traffic Management in Michigan

    OpenAIRE

    Johnson, Pat

    2018-01-01

    The US 23 Flex Route is the first active traffic management (ATM) project in the state of Michigan. This route utilizes overhead lane control gantries equipped with various intelligent transportation system (ITS) equipment to facilitate the following ATM strategies: dynamic shoulder use, dynamic lane control, variable speed advisories, and queue warning. The focus of this presentation is how the project team overcame several challenges during the planning, design, and system management phases...

  19. Vacation queueing models theory and applications

    CERN Document Server

    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...

  20. Adaptive Filtering Queueing for Improving Fairness

    Directory of Open Access Journals (Sweden)

    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.

  1. Preventing messaging queue deadlocks in a DMA environment

    Science.gov (United States)

    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.

  2. Managing patients' wait time in specialist out-patient clinic using real-time data from existing queue management and ADT systems.

    Science.gov (United States)

    Ju, John Chen; Gan, Soon Ann; Tan Siew Wee, Justine; Huang Yuchi, Peter; Mei Mei, Chan; Wong Mei Mei, Sharon; Fong, Kam Weng

    2013-01-01

    In major cancer centers, heavy patients load and multiple registration stations could cause significant wait time, and can be result in patient complains. Real-time patient journey data and visual display are useful tools in hospital patient queue management. This paper demonstrates how we capture patient queue data without deploying any tracing devices; and how to convert data into useful patient journey information to understand where interventions are likely to be most effective. During our system development, remarkable effort has been spent on resolving data discrepancy and balancing between accuracy and system performances. A web-based dashboard to display real-time information and a framework for data analysis were also developed to facilitate our clinics' operation. Result shows our system could eliminate more than 95% of data capturing errors and has improved patient wait time data accuracy since it was deployed.

  3. Gender and socioeconomic status as determinants of waiting time for inpatient surgery in a system with implicit queue management.

    Science.gov (United States)

    Arnesen, Kjell E; Erikssen, Jan; Stavem, Knut

    2002-12-01

    In a system with implicit queue management, to examine gender and socioeconomic status as determinants of waiting time for inpatient surgery, after adjusting for other potential predictors. A cohort of 452 subjects was examined in outpatient clinics of a general hospital and referred to inpatient surgery. They were followed until scheduled hospital admission (n=396) or until the requested procedure no longer was relevant (n=56). We compared waiting time between groups from referral date until hospital admission, using Kaplan-Meier estimates of waiting times and log rank test. A Cox proportional hazards model was used for assessing the risk ratio (RR) of hospital admission for scheduled surgery. Gender and socioeconomic status could not explain variations in waiting time. However, patients with suspected/verified neoplastic disease or a risk of serious deterioration without treatment had markedly shorter waiting times than the reference groups, with adjusted RR (95% confidence intervals (95%CI)) of time to receiving in-patient surgery of 2.3 (1.7-3.0) and 2.0 (1.3-3.0), respectively. Being on sick leave was associated with shorter waiting time, adjusted RR of 1.7 (1.2-2.5). Referrals from within the hospital or other hospitals had also shorter waiting times than referrals from primary health care physicians, adjusted RR=1.4 (1.1-1.8). There was no evidence of bias against women or people in lower socioeconomic classes in this implicit queue management system. However, patients' access to inpatient surgery was associated with malignancy, prognosis, sick leave status, physician experience, referral pattern and the major diagnosis category.

  4. Near-optimal switching strategies for a tandem queue

    NARCIS (Netherlands)

    van Leeuwen, D.; Núñez-Queija, R.; Boucherie, R.J.; van Dijk, N.M.

    2017-01-01

    Motivated by various applications in logistics, road traffic and production management, we investigate two versions of a tandem queueing model in which the service rate of the first queue can be controlled. The objective is to keep the mean number of jobs in the second queue as low as possible,

  5. Near-optimal switching strategies for a tandem queue

    NARCIS (Netherlands)

    D. van Leeuwen (Daphne); R. Núñez Queija (Rudesindo)

    2017-01-01

    textabstractMotivated by various applications in logistics, road traffic and production management, we investigate two versions of a tandem queueing model in which the service rate of the first queue can be controlled. The objective is to keep the mean number of jobs in the second queue as low as

  6. Planning for active traffic management in Virginia : international best practices and implementation strategies.

    Science.gov (United States)

    2012-10-01

    Active Traffic Management (ATM) applications, such as variable speed limits, queue warning systems, and dynamic : ramp metering, have been shown to offer mobility and safety benefits. Yet because they differ from conventional capacity : investments i...

  7. Architecture and robustness tradeoffs in speed-scaled queues with application to energy management

    Science.gov (United States)

    Dinh, Tuan V.; Andrew, Lachlan L. H.; Nazarathy, Yoni

    2014-08-01

    We consider single-pass, lossless, queueing systems at steady-state subject to Poisson job arrivals at an unknown rate. Service rates are allowed to depend on the number of jobs in the system, up to a fixed maximum, and power consumption is an increasing function of speed. The goal is to control the state dependent service rates such that both energy consumption and delay are kept low. We consider a linear combination of the mean job delay and energy consumption as the performance measure. We examine both the 'architecture' of the system, which we define as a specification of the number of speeds that the system can choose from, and the 'design' of the system, which we define as the actual speeds available. Previous work has illustrated that when the arrival rate is precisely known, there is little benefit in introducing complex (multi-speed) architectures, yet in view of parameter uncertainty, allowing a variable number of speeds improves robustness. We quantify the tradeoffs of architecture specification with respect to robustness, analysing both global robustness and a newly defined measure which we call local robustness.

  8. A course on queueing models

    CERN Document Server

    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

  9. Probability, statistics, and queueing theory

    CERN Document Server

    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

  10. The WIYN Queue: Theory Meets Reality

    Science.gov (United States)

    Boroson, T. A.; Harmer, D. L.; Saha, A.; Smith, P. S.; Willmarth, D. W.; Silva, D. R.

    1998-07-01

    During the past two years NOAO has conducted a queue observing experiment with the 3.5 m WIYN telescope on Kitt Peak, Arizona. The WIYN telescope is ideally suited to queue-scheduled operation in terms of its performance and its instrument complement. The queue scheduling experiment on WIYN was designed to test a number of beliefs and hypotheses about gains in efficiency and scientific effectiveness due to queue scheduling. In addition, the experiment was a test of our implementation strategy and management of community expectations. The queue is run according, to a set of rules that guide decisions about which observation to do next. In practice, scientific rank, suitability of current conditions, and the desire to complete programs all enter into these decisions. As predicted by Monte Carlo simulations, the queue increases the overall efficiency of the telescope, particularly for observations requiring, rare conditions. Together with this improvement for typical programs, the queue enables synoptic, target-of-opportunity, and short programs that could not be scheduled classically. Despite this success, a number of sociological issues determine the community's perception of the WIYN queue.

  11. Fluid queues and regular variation

    NARCIS (Netherlands)

    Boxma, O.J.

    1996-01-01

    This paper considers a fluid queueing system, fed by N independent sources that alternate between silence and activity periods. We assume that the distribution of the activity periods of one or more sources is a regularly varying function of index ¿. We show that its fat tail gives rise to an even

  12. Fluid queues and regular variation

    NARCIS (Netherlands)

    O.J. Boxma (Onno)

    1996-01-01

    textabstractThis paper considers a fluid queueing system, fed by $N$ independent sources that alternate between silence and activity periods. We assume that the distribution of the activity periods of one or more sources is a regularly varying function of index $zeta$. We show that its fat tail

  13. Mathematical Analysis of Queue with Phase Service: An Overview

    Directory of Open Access Journals (Sweden)

    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.

  14. discouraged by queue length

    Directory of Open Access Journals (Sweden)

    P. R. Parthasarathy

    2001-01-01

    Full Text Available The transient solution is obtained analytically using continued fractions for a state-dependent birth-death queue in which potential customers are discouraged by the queue length. This queueing system is then compared with the well-known infinite server queueing system which has the same steady state solution as the model under consideration, whereas their transient solutions are different. A natural measure of speed of convergence of the mean number in the system to its stationarity is also computed.

  15. Increasing available FIFO space to prevent messaging queue deadlocks in a DMA environment

    Science.gov (United States)

    Blocksome, Michael A [Rochester, MN; Chen, Dong [Croton On Hudson, NY; Gooding, Thomas [Rochester, MN; Heidelberger, Philip [Cortlandt Manor, NY; Parker, Jeff [Rochester, MN

    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.

  16. Fast meldable priority queues

    DEFF Research Database (Denmark)

    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...

  17. Management of queues in out-patient departments: the use of computer simulation.

    Science.gov (United States)

    Aharonson-Daniel, L; Paul, R J; Hedley, A J

    1996-01-01

    Notes that patients attending public outpatient departments in Hong Kong spend a long time waiting for a short consultation, that clinics are congested and that both staff and patients are dissatisfied. Points out that experimentation of management changes in a busy clinical environment can be both expensive and difficult. Demonstrates computerized simulation modelling as a potential tool for clarifying processes occurring within such systems, improving clinic operation by suggesting possible answers to problems identified and evaluating the solutions, without interfering with the clinic routine. Adds that solutions can be implemented after they had proved to be successful on the model. Demonstrates some ways in which managers in health care facilities can benefit from the use of computerized simulation modelling. Specifically, shows the effect of changing the duration of consultation and the effect of the application of an appointment system on patients' waiting time.

  18. An asymmetric shortest queue problem

    NARCIS (Netherlands)

    Adan, I.J.B.F.; Wessels, J.; Zijm, W.H.M.

    1989-01-01

    In this paper we study a system consisting of two identical servers, each with exponentially distributed service times. Jobs arrive according to a Poisson stream. On arrival a job joins the shortest queue and in case both queues have equal length. he joins queue 1 say with probability q and queue 2

  19. Concurrent array-based queue

    Science.gov (United States)

    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.

  20. Sex-related differences in coronary revascularization practices: the perspective from a Canadian queue management project.

    Science.gov (United States)

    Naylor, C D; Levinton, C M

    1993-10-01

    To assess sex-related differences in coronary revascularization practices in a Canadian setting. Prospective analytic cohort study. Regional referral office in Toronto. A selected but consecutive group of 131 women and 440 men referred by cardiologists for revascularization procedures between Jan. 3, 1989, and June 30, 1991. Coronary artery bypass grafting (CABG) or percutaneous transluminal coronary angioplasty (PTCA). Nurse-coordinators placed the referral with a surgeon or interventional cardiologist at one of three hospitals, who then communicated directly with the referring cardiologist. Symptom status at referral, procedures requested and performed, and time from referral to procedure. Although the women were more likely than the men to have unstable angina at the time of referral (odds ratio [OR] 2.28, 95% confidence interval [CI] 1.38 to 3.79, p = 0.0006), more women than men (16.8% v. 12.1%) were turned down for a procedure. Significant sex-related differences in practice patterns (p management; sex was the only other significant variable (p = 0.016). The referring physicians requested CABG more often for men than for women (p = 0.009), and the men accepted for a procedure were much more likely to undergo CABG than the women (OR 2.40, CI 1.47 to 3.93, p = 0.0002). Although the women undergoing CABG waited shorter periods than the men (p = 0.0035), this difference was attributable to their more severe symptoms. In this selected group women had more serious symptoms before referral but were turned down for revascularization more often than men. Reduced use of CABG rather than PTCA largely accounted for the sex-related differences in revascularization. Once accepted for a procedure women had shorter waiting times, which was appropriate given their more severe symptoms.

  1. Fundamentals of queueing theory

    CERN Document Server

    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

  2. The queue-length in GI/G/s queues

    Directory of Open Access Journals (Sweden)

    Le Gall Pierre

    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.

  3. Single server queueing networks with varying service times and renewal input

    Directory of Open Access Journals (Sweden)

    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.

  4. Interacting queues in heavy traffic

    NARCIS (Netherlands)

    J.A. Morrison; S.C. Borst (Sem)

    2010-01-01

    htmlabstractWe consider a system of parallel queues with Poisson arrivals and exponentially distributed service requirements. The various queues are coupled through their service rates, causing a complex dynamic interaction. Specifically, the system consists of one primary queue and several

  5. The symmetric longest queue system

    NARCIS (Netherlands)

    van Houtum, Geert-Jan; Adan, Ivo; van der Wal, Jan

    1997-01-01

    We derive the performance of the exponential symmetric longest queue system from two variants: a longest queue system with Threshold Rejection of jobs and one with Threshold Addition of jobs. It is shown that these two systems provide lower and upper bounds for the performance of the longest queue

  6. Australia: a matter of Queues and As

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-05-15

    Australia has been very much in the news recently, with ship queues at port terminals and storms hitting the Hunter Valley, flooding coal yards and rail links. In December 2006 a 'capacity balancing system' (CBS) introduced by Port Waratah Coal Services to solve queuing problems in Newcastle ports in mid-2004 was discontinued but then the queues started to grow again. A new CBS was introduced and was beginning to take effect when storms struck New South Wales. Port Dalrymple Coal Services has a queue management system but nevertheless there were 58 ships waiting in Dalrymple Bay and Hay Point in late June. A number of coal terminals are undergoing expansion in an attempt to solve the situation. 4 photos.

  7. Labour costs and queueing theory in retailing

    NARCIS (Netherlands)

    J.B.G. Frenk (Hans); A.R. Thurik (Roy); C.A. Bout

    1991-01-01

    textabstractIn this paper approximation results for the M/G/s queueing model are used to derive an empirically verified shop type dependent non-homogeneous relation between labour volume and sales in retail trade. Moreover, we formulate the retailer's labour management as a formal minimization

  8. Bad Luck When Joining the Shortest Queue

    NARCIS (Netherlands)

    Blanc, J.P.C.

    2008-01-01

    A frequent observation in service systems with queues in parallel is that customers in other queues tend to be served faster than those in one’s own queue. This paper quantifies the probability that one’s service would have started earlier if one had joined another queue than the queue that was

  9. A Survey on Priority Queues

    DEFF Research Database (Denmark)

    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 qu...

  10. Lévy-driven queues

    NARCIS (Netherlands)

    Debicki, K.G.; Mandjes, M.R.H.

    2012-01-01

    This survey addresses the class of queues with Lévy input, which covers the classical M/G/1 queue and the reflected Brownian motion as special cases. First the stationary behavior is treated, with special attention to the case of the input process having one-sided jumps (i.e., spectrally one-sided

  11. Optimal purely functional priority queues

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Okasaki, Chris

    1996-01-01

    Brodal recently introduced the first implementation of imperative priority queues to support findMin, insert and meld in O(1) worst-case time, and deleteMin in O(log n) worst-case time. These bounds are asymptotically optimal among all comparison-based priority queues. In this paper, we adapt...... 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......: first, we reduce the running time of insert to O(1) by eliminating the possibility of cascading links; second, we reduce the running time of findMin to O(1) by adding a global root to hold the minimum element; and finally, we reduce the running time of meld to O(1) by allowing priority queues to contain...

  12. Self-Interested Routing in Queueing Networks

    OpenAIRE

    Ali K. Parlaktürk; Sunil Kumar

    2004-01-01

    We study self-interested routing in stochastic networks, taking into account the discrete stochastic dynamics of such networks. We analyze a two-station multiclass queueing network in which the system manager chooses the scheduling rule and individual customers choose routes in a self-interested manner. We show that this network can be unstable in Nash equilibrium under some scheduling rules. We also design a nontrivial scheduling rule that negates the performance degradation resulting from s...

  13. Applied discrete-time queues

    CERN Document Server

    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...

  14. Manajemen Bandwidth Simple Queue dan Queue Tree pada PT. Endorsindo Makmur Selaras

    OpenAIRE

    Budiman, Arif

    2015-01-01

      The purpose of this study is to analyze and optimize the bandwidth management at PT. Endorsindo Makmur Selaras, with the expectation that the distribution of bandwidth can be evenly distributed to each employee so that the employee can improve performance and quality of the company. Research methods used include analysis methods (survey and interview system that runs directly on the user) and to optimize bandwidth management method to configure the proxy using the Queue Tree. The re...

  15. The MX/G/1 queue with queue length dependent service times

    Directory of Open Access Journals (Sweden)

    Bong Dae Choi

    2001-01-01

    Full Text Available We deal with the MX/G/1 queue where service times depend on the queue length at the service initiation. By using Markov renewal theory, we derive the queue length distribution at departure epochs. We also obtain the transient queue length distribution at time t and its limiting distribution and the virtual waiting time distribution. The numerical results for transient mean queue length and queue length distributions are given.

  16. Equilibrium Arrival Times to Queues

    DEFF Research Database (Denmark)

    Breinbjerg, Jesper; Østerdal, Lars Peter

    We consider a non-cooperative queueing environment where a finite number of customers independently choose when to arrive at a queueing system that opens at a given point in time and serves customers on a last-come first-serve preemptive-resume (LCFS-PR) basis. Each customer has a service time...... requirement which is identically and independently distributed according to some general probability distribution, and they want to complete service as early as possible while minimizing the time spent in the queue. In this setting, we establish the existence of an arrival time strategy that constitutes...... a symmetric (mixed) Nash equilibrium, and show that there is at most one symmetric equilibrium. We provide a numerical method to compute this equilibrium and demonstrate by a numerical example that the social effciency can be lower than the effciency induced by a similar queueing system that serves customers...

  17. Optimal control of two queues in series

    International Nuclear Information System (INIS)

    Moustafa, M.S.; Mohammed, R.M.

    1994-08-01

    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

  18. JobCenter: an open source, cross-platform, and distributed job queue management system optimized for scalability and versatility

    Directory of Open Access Journals (Sweden)

    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/.

  19. JobCenter: an open source, cross-platform, and distributed job queue management system optimized for scalability and versatility.

    Science.gov (United States)

    Jaschob, Daniel; Riffle, Michael

    2012-07-30

    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. 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. 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/.

  20. Queue-length balance equations in multiclass multiserver queues and their generalizations

    NARCIS (Netherlands)

    Boon, M.A.A.; Boxma, O.J.; Kella, O.; Miyazawa, M.

    2017-01-01

    A classical result for the steady-state queue-length distribution of single-class queueing systems is the following: The distribution of the queue length just before an arrival epoch equals the distribution of the queue length just after a departure epoch. The constraint for this result to be valid

  1. Queue-length balance equations in multiclass multiserver queues and their generalizations

    NARCIS (Netherlands)

    Boon, M.; Boxma, O.J.; Kella, O.; Miyazawa, M.

    2017-01-01

    A classical result for the steady-state queue-length distribution of single-class queueing systems is the following: the distribution of the queue length just before an arrival epoch equals the distribution of the queue length just after a departure epoch. The constraint for this result to be valid

  2. Decomposing the queue length distribution of processor-sharing models into queue lengths of permanent customer queues

    NARCIS (Netherlands)

    Cheung, S.K.; van den Berg, Hans Leo; Boucherie, Richardus J.

    2005-01-01

    We obtain a decomposition result for the steady state queue length distribution in egalitarian processor-sharing (PS) models. In particular, for an egalitarian PS queue with $K$ customer classes, we show that the marginal queue length distribution for class $k$ factorizes over the number of other

  3. Queueing networks a fundamental approach

    CERN Document Server

    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...

  4. Random queues and risk averse users

    DEFF Research Database (Denmark)

    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...

  5. Optimal dispatching in a tandem queue

    NARCIS (Netherlands)

    van Leeuwen, D.; Núñez Queija, R.

    2017-01-01

    We investigate a Markovian tandem queueing model in which service to the first queue is provided in batches. The main goal is to choose the batch sizes so as to minimize a linear cost function of the mean queue lengths. This model can be formulated as a Markov Decision Process (MDP) for which the

  6. Analysis of the shortest queue problem

    NARCIS (Netherlands)

    Adan, I.J.B.F.; Wessels, J.; Zijm, W.H.M.

    1989-01-01

    In this paper we study a system consisting of two identical servers, each with exponentially distributed service times. Jobs arrive according to a Poisson stream. On arrival a job joins the shortest queue and in case both queues have equal length, he joins either queue with probability ½. We show

  7. Analysis of the symmetric shortest queue problem

    NARCIS (Netherlands)

    Adan, I.J.B.F.; Wessels, J.; Zijm, W.H.M.

    1990-01-01

    In this paper we study a system consisting of two identical servers, each with exponentially distributed service times. Jobs arrive according to a Poisson stream. On· arrival a job joins the shortest queue and in case both queues have equal lengths, he joins either queue with probability ½. By using

  8. Analysis of the symmetric shortest queue problem

    NARCIS (Netherlands)

    Adan, I.J.B.F.; Wessels, J.; Zijm, W.H.M.

    1990-01-01

    In this paper we study a system consisting of two identical servers, each with exponentially distributed service times. Jobs arrive according to a Poisson stream. On arrival a job joins the shortest queue and in case both queues have equal lengths, he joins either queue with probability 1/2. By

  9. Research into Queueing Network Theory.

    Science.gov (United States)

    1977-09-01

    and Zeigler, B. (1975) "Equilibrium properties of arbitrarily interconnected queueing netowrks ," Tech. Report 75-4, Computer and Communication...Associate. The project was extremely fortunate to secure the services of Dr. Wendel. Dr. Wendel was a project member for one month in the summer of

  10. Asymptotic inference for waiting times and patiences in queues with abandonment

    DEFF Research Database (Denmark)

    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...

  11. Asymptotic inference for waiting times and patiences in queues with abandonment

    DEFF Research Database (Denmark)

    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...

  12. Dynamic server assignment in a two-queue model

    NARCIS (Netherlands)

    O.J. Boxma (Onno); D.G. Down

    1995-01-01

    textabstractWe consider a polling model of two $M/G/1$ queues, served by a single server. The service policy for this polling model is of threshold type. Service at queue 1 is exhaustive. Service at queue 2 is exhaustive unless the size of queue 1 reaches some level $T$ during a service at queue 2;

  13. Dynamic server assignment in a two-queue model

    NARCIS (Netherlands)

    Boxma, O.J.; Down, D.G.

    1997-01-01

    We consider a polling model of two M/G/1 queues, served by a single server. The service policy for this polling model is of threshold type. Service at queue 1 is exhaustive. Service at queue 2 is exhaustive unless the size of queue 1 reaches some level T during a service at queue 2; in the latter

  14. Terminal Appointment System Design by Non-stationary M(t)/Ek/c(t) Queueing Model and Genetic Algorithm

    DEFF Research Database (Denmark)

    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...

  15. Analysis of queues methods and applications

    CERN Document Server

    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

  16. Delay in a tandem queueing model with mobile queues: An analytical approximation

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; de Haan, Roland; Boucherie, Richardus J.; van Ommeren, Jan C.W.

    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

  17. Priority Queues Resilient to Memory Faults

    DEFF Research Database (Denmark)

    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...... queues storing only structural information in the uncorruptible registers between operations....

  18. Curing the queue

    NARCIS (Netherlands)

    Zonderland, Maartje Elisabeth

    2012-01-01

    In this dissertation we study several problems related to the management of healthcare and the cure of disease. In each chapter a hospital capacity distribution problem is analyzed using techniques from operations research, also known as mathematical decision theory. The problems considered are

  19. Application of queueing models to multiprogrammed computer systems operating in a time-critical environment

    Science.gov (United States)

    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.

  20. GPS queues with heterogeneous traffic classes

    NARCIS (Netherlands)

    Borst, Sem; Mandjes, M.R.H.; van Uitert, Miranda

    2002-01-01

    We consider a queue fed by a mixture of light-tailed and heavy-tailed traffic. The two traffic classes are served in accordance with the generalized processor sharing (GPS) discipline. GPS-based scheduling algorithms, such as weighted fair queueing (WFQ), have emerged as an important mechanism for

  1. A tandem queue with delayed server release

    NARCIS (Netherlands)

    Nawijn, W.M.

    1997-01-01

    We consider a tandem queue with two stations. The rst station is an s-server queue with Poisson arrivals and exponential service times. After terminating his service in the rst station, a customer enters the second station to require service at an exponential single server, while in the meantime he

  2. Analysis of the asymmetric shortest queue problem

    NARCIS (Netherlands)

    Adan, I.J.B.F.; Wessels, J.; Zijm, W. H M

    1991-01-01

    In this paper we study a system consisting of two parallel servers with different service rates. Jobs arrive according to a Poisson stream and generate an exponentially distributed workload. On arrival a job joins the shortest queue and in case both queues have equal lengths, he joins the first

  3. Tandem queue with server slow-down

    NARCIS (Netherlands)

    Miretskiy, D.I.; Scheinhardt, W.R.W.; Mandjes, M.R.H.

    2007-01-01

    We study how rare events happen in the standard two-node tandem Jackson queue and in a generalization, the socalled slow-down network, see [2]. In the latter model the service rate of the first server depends on the number of jobs in the second queue: the first server slows down if the amount of

  4. Analysis of the asymmetric shortest queue problem

    NARCIS (Netherlands)

    Adan, I.J.B.F.; Wessels, J.; Zijm, W.H.M.

    1990-01-01

    In this paper we study a system consisting of two parallel servers with different service rates. Jobs arrive according to a Poisson stream and generate an exponentially distributed workload. On arrival a job joins the shortest queue and in case both queues have equal lengths, he joins the first

  5. On the dependence structure of Gaussian queues

    NARCIS (Netherlands)

    Es-Saghouani, A.; Mandjes, M.R.H.

    2009-01-01

    In this article we study Gaussian queues (that is, queues fed by Gaussian processes, such as fractional Brownian motion (fBm) and the integrated Ornstein-Uhlenbeck (iOU) process), with a focus on the dependence structure of the workload process. The main question is to what extent does the workload

  6. Queues and Lévy Fluctuation Theory

    NARCIS (Netherlands)

    Dębicki, K.; Mandjes, M.

    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,

  7. Survey on queueing models with standbys support

    Directory of Open Access Journals (Sweden)

    Kolledath Sreekanth

    2018-01-01

    Full Text Available This paper is a survey article on queueing models with standbys support. Due to many real life applications of queueing models, it has become an interesting area for researchers and a lot of research work has been exerted so far. It is worthwhile to examine the performance based analysis for queueing modelling system as it provides a valuable insight to the tractability of the system and accelerates its efficiency. The provision of standbys to the queueing modelling of a real system is needed for smooth functioning in the presence of its unavoidable failures. The present survey provides a dig into the research work done, and emphasis the sequential developments on queueing models with standbys support.

  8. Priority Queues Resilient to Memory Faults

    DEFF Research Database (Denmark)

    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...

  9. MANAGEMENT AND SPORTING ACTIVITIES

    Directory of Open Access Journals (Sweden)

    MONICA DELIA BÎCĂ

    2015-10-01

    Full Text Available “Using applied science in sport management as creates opportunities for rationalization and systematization of sports activity, relying on the knowledge and application of the laws that control the dynamics and phenomena. Management is on the border between art and science. Arts management is manifested by "science" as opposed to use and harness the creative compromise that can produce increased efficiency and effectiveness.”

  10. On the single-server retrial queue

    Directory of Open Access Journals (Sweden)

    Djellab Natalia V.

    2006-01-01

    Full Text Available In this work, we review the stochastic decomposition for the number of customers in M/G/1 retrial queues with reliable server and server subjected to breakdowns which has been the subject of investigation in the literature. Using the decomposition property of M/G/1 retrial queues with breakdowns that holds under exponential assumption for retrial times as an approximation in the non-exponential case, we consider an approximate solution for the steady-state queue size distribution.

  11. Queues and Lévy fluctuation theory

    CERN Document Server

    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.

  12. Activation/waste management

    International Nuclear Information System (INIS)

    Maninger, C.

    1984-10-01

    The selection of materials and the design of the blankets for fusion reactors have significant effects upon the radioactivity generated by neutron activation in the materials. This section considers some aspects of materials selection with respect to waste management. The activation of the materials is key to remote handling requirements for waste, to processing and disposal methods for waste, and to accident severity in waste management operations. In order to realize the desirable evnironmental potentials of fusion power systems, there are at least three major goals for waste management. These are: (a) near-surface burial; (b) disposal on-site of the fusion reactor; (c) acceptable radiation doses at least cost during and after waste management operations

  13. Exclusive queueing model including the choice of service windows

    Science.gov (United States)

    Tanaka, Masahiro; Yanagisawa, Daichi; Nishinari, Katsuhiro

    2018-01-01

    In a queueing system involving multiple service windows, choice behavior is a significant concern. This paper incorporates the choice of service windows into a queueing model with a floor represented by discrete cells. We contrived a logit-based choice algorithm for agents considering the numbers of agents and the distances to all service windows. Simulations were conducted with various parameters of agent choice preference for these two elements and for different floor configurations, including the floor length and the number of service windows. We investigated the model from the viewpoint of transit times and entrance block rates. The influences of the parameters on these factors were surveyed in detail and we determined that there are optimum floor lengths that minimize the transit times. In addition, we observed that the transit times were determined almost entirely by the entrance block rates. The results of the presented model are relevant to understanding queueing systems including the choice of service windows and can be employed to optimize facility design and floor management.

  14. Network resiliency through memory health monitoring and proactive management

    Science.gov (United States)

    Andrade Costa, Carlos H.; Cher, Chen-Yong; Park, Yoonho; Rosenburg, Bryan S.; Ryu, Kyung D.

    2017-11-21

    A method for managing a network queue memory includes receiving sensor information about the network queue memory, predicting a memory failure in the network queue memory based on the sensor information, and outputting a notification through a plurality of nodes forming a network and using the network queue memory, the notification configuring communications between the nodes.

  15. E-Queue Mobile Application

    Directory of Open Access Journals (Sweden)

    Khong Yeen Lai

    2017-01-01

    Full Text Available Waiting in line is a common experience in daily life, whether for a table at a popular restaurant or for the service at a bank. This experience is not always pleasant for most of people because they always have to wait for a long time to be serviced. The ability to interact with waiting customers is highly desirable because it allows businesses the opportunity to optimize their existing services and offer new services to waiting customers. However, interacting with individuals waiting in a queue has been inefficient and costly because employees must either talk with each waiting customer on an ongoing basis or the business must provide high tech devices that interact with each waiting customer. Agile methodology which will be used to develop this application, it incorporates the SDLC phases starting from the Planning phase up to the Maintenance phase. End of the research, we found that majority of respondents are prefer to use the proposed system compared with current method.

  16. Problem situations in management activity

    OpenAIRE

    N.A. DUBINKO

    2009-01-01

    This article reviews contemporary methodological and theoretical approaches to the problem situations in management activity. Revealed and analyzed the types of problem situations managers dealing with in their activity. Rank correlation of problem situations shows distinctions depending on management work experience. Revealed gender distinctions in the managers' ideas of management problems.

  17. Performance optimization of queueing systems with perturbation realization

    KAUST Repository

    Xia, Li; Cao, Xiren

    2012-01-01

    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

  18. Computing moving and intermittent queue propagation in highway work zones.

    Science.gov (United States)

    2012-07-01

    Drivers may experience intermittent congestion and moving queue conditions in work zones due to several reasons such as presence of lane closure, roadway geometric changes, higher demand, lower speed, and reduced capacity. The congestion and queue ha...

  19. State-dependent importance sampling for a slowdown tandem queue

    NARCIS (Netherlands)

    Miretskiy, D.I.; Scheinhardt, W.R.W.; Mandjes, M.R.H.

    2011-01-01

    In this paper we investigate an advanced variant of the classical (Jackson) tandem queue, viz. a two-node system with server slowdown. By this mechanism, the service speed of the upstream queue is reduced as soon as the number of jobs in the downstream queue reaches some pre-specified threshold. We

  20. Discovering queues from event logs with varying levels of information

    NARCIS (Netherlands)

    Senderovich, A.; Leemans, S,J.J.; Harel, S.; Gal, A.; Mandelbaum, A.; van der Aalst, W.M.P.; Reichert, M.; Reijers, H.A.

    2016-01-01

    Detecting and measuring resource queues is central to business process optimization. Queue mining techniques allow for the identification of bottlenecks and other process inefficiencies, based on event data. This work focuses on the discovery of resource queues. In particular, we investigate the

  1. Difference and differential equations with applications in queueing theory

    CERN Document Server

    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

  2. A tandem queue with delayed server release

    OpenAIRE

    Nawijn, W.M.

    1997-01-01

    We consider a tandem queue with two stations. The rst station is an s-server queue with Poisson arrivals and exponential service times. After terminating his service in the rst station, a customer enters the second station to require service at an exponential single server, while in the meantime he is blocking his server in station 1 until he completes service in station 2, whereupon the server in station 1 is released. An analysis of the generating function of the simultaneous probability di...

  3. Stochastic Processes and Queueing Theory used in Cloud Computer Performance Simulations

    Directory of Open Access Journals (Sweden)

    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.

  4. Dobrushin's approach to queueing network theory

    Directory of Open Access Journals (Sweden)

    F. I. Karpelevich

    1996-01-01

    Full Text Available R.L. Dobrushin (1929-1995 made substantial contributions to Queueing Network Theory (QNT. A review of results from QNT which arose from his ideas or were connected to him in other ways is given. We also comment on various related open problems.

  5. An Evaluation of Concurrent Priority Queue Algorithms

    Science.gov (United States)

    1991-02-01

    path pronlem are testedi A! -S7 ?o An Evaluation of Concurrent Priority Queue Algorithms bv Qin Huang BS. Uiversity - of Science andi Technology of China...who have always supported me through my entire career and made my life more enjoyable. This research was supported in part by the Advanced Research

  6. Buffer Overflow Period in a MAP Queue

    Directory of Open Access Journals (Sweden)

    Andrzej Chydzinski

    2007-01-01

    Full Text Available The buffer overflow period in a queue with Markovian arrival process (MAP and general service time distribution is investigated. The results include distribution of the overflow period in transient and stationary regimes and the distribution of the number of cells lost during the overflow interval. All theorems are illustrated via numerical calculations.

  7. Open problems in Gaussian fluid queueing theory

    NARCIS (Netherlands)

    Dȩbicki, K.; Mandjes, M.

    2011-01-01

    We present three challenging open problems that originate from the analysis of the asymptotic behavior of Gaussian fluid queueing models. In particular, we address the problem of characterizing the correlation structure of the stationary buffer content process, the speed of convergence to

  8. QUEUEING DISCIPLINES BASED ON PRIORITY MATRIX

    Directory of Open Access Journals (Sweden)

    Taufik I. Aliev

    2014-11-01

    Full Text Available The paper deals with queueing disciplines for demands of general type in queueing systems with multivendor load. A priority matrix is proposed to be used for the purpose of mathematical description of such disciplines, which represents the priority type (preemptive priority, not preemptive priority or no priority between any two demands classes. Having an intuitive and simple way of priority assignment, such description gives mathematical dependencies of system operation characteristics on its parameters. Requirements for priority matrix construction are formulated and the notion of canonical priority matrix is given. It is shown that not every matrix, constructed in accordance with such requirements, is correct. The notion of incorrect priority matrix is illustrated by an example, and it is shown that such matrixes do not ensure any unambiguousness and determinacy in design of algorithm, which realizes corresponding queueing discipline. Rules governing construction of correct matrixes are given for canonical priority matrixes. Residence time for demands of different classes in system, which is the sum of waiting time and service time, is considered as one of the most important characteristics. By introducing extra event method Laplace transforms for these characteristics are obtained, and mathematical dependencies are derived on their basis for calculation of two first moments for corresponding characteristics of demands queueing

  9. Markov-modulated and feedback fluid queues

    NARCIS (Netherlands)

    Scheinhardt, Willem R.W.

    1998-01-01

    In the last twenty years the field of Markov-modulated fluid queues has received considerable attention. In these models a fluid reservoir receives and/or releases fluid at rates which depend on the actual state of a background Markov chain. In the first chapter of this thesis we give a short

  10. Adaptive Importance Sampling Simulation of Queueing Networks

    NARCIS (Netherlands)

    de Boer, Pieter-Tjerk; Nicola, V.F.; Rubinstein, N.; Rubinstein, Reuven Y.

    2000-01-01

    In this paper, a method is presented for the efficient estimation of rare-event (overflow) probabilities in Jackson queueing networks using importance sampling. The method differs in two ways from methods discussed in most earlier literature: the change of measure is state-dependent, i.e., it is a

  11. Designing of vague logic based multilevel feedback queue scheduler

    Directory of Open Access Journals (Sweden)

    Supriya Raheja

    2016-03-01

    Full Text Available Multilevel feedback queue scheduler suffers from major issues of scheduling such as starvation for long tasks, fixed number of queues, and static length of time quantum in each queue. These factors directly affect the performance of the scheduler. At many times impreciseness exists in attributes of tasks which make the performance even worse. In this paper, our intent is to improve the performance by providing a solution to these issues. We design a multilevel feedback queue scheduler using a vague set which we call as VMLFQ scheduler. VMLFQ scheduler intelligently handles the impreciseness and defines the optimum number of queues as well as the optimal size of time quantum for each queue. It also resolves the problem of starvation. This paper simulates and analyzes the performance of VMLFQ scheduler with the other multilevel feedback queue techniques using MatLab.

  12. Optimal control of arrival and service rates in tandem queues

    International Nuclear Information System (INIS)

    Moustafa, M.S.

    1995-08-01

    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

  13. Uranium management activities

    International Nuclear Information System (INIS)

    Jackson, D.; Marshall, E.; Sideris, T.; Vasa-Sideris, S.

    2001-01-01

    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)

  14. A two-queue model with alternating limited service and state-dependent setups

    NARCIS (Netherlands)

    Winands, E.M.M.; Adan, I.J.B.F.; Houtum, van G.J.J.A.N.; Papadopoulos, C.T.

    2005-01-01

    We consider a two-queue model with state-dependent setups, in which a single server alternately serves the two queues. The high-priority queue is served exhaustively, whereas the low-priority queue is served according to the k-limited strategy. We obtain the transforms of the queue length and

  15. Simple and efficient importance sampling scheme for a tandem queue with server slow-down

    NARCIS (Netherlands)

    Miretskiy, D.I.; Scheinhardt, W.R.W.; Mandjes, M.R.H.

    2008-01-01

    This paper considers importance sampling as a tool for rare-event simulation. The system at hand is a so-called tandem queue with slow-down, which essentially means that the server of the first queue (or: upstream queue) switches to a lower speed when the second queue (downstream queue) exceeds some

  16. [Active management of labor].

    Science.gov (United States)

    Ruiz Ortiz, E; Villalobos Román, M; Flores Murrieta, G; Sotomayor Alvarado, L

    1991-01-01

    Eighty three primigravidae patients at the end of latency labor, erased cervix, 3 cm dilation, vertex presentation and adequate pelvis, were studied. Two groups were formed: 53 patients in the study group, who received active management of labor, and 30 patients in the control group, treated in the traditional way. In all the patients a graphic recording of labor, was carried out; it included all the events, and as labor advanced, a signoidal curve of cervical dilatation, was registered, as well as the hyperbolic one for presentation descent. The study group received the method in a systematized manner, as follows: 1. Peridular block. 2. Amniotomy. 3. IV oxytocin one hour after amniotomy. 4. FCR monitoring. 5. Detection of dystocia origin. Materno-fetal morbidity was registered in both groups, as well as cesarean section rate, instrumental delivery and its indications, labor duration, and time of stay in labor room. Diminution of above intems and opportune detection of dystocia, were determined. It was concluded that a constructive action plan, starting at hospital admission in most healthy women, allows a normal delivery of brief duration.

  17. Chimpanzee females queue but males compete for social status

    Science.gov (United States)

    Foerster, Steffen; Franz, Mathias; Murray, Carson M.; Gilby, Ian C.; Feldblum, Joseph T.; Walker, Kara K.; Pusey, Anne E.

    2016-01-01

    Dominance hierarchies are widespread in animal social groups and often have measureable effects on individual health and reproductive success. Dominance ranks are not static individual attributes, however, but instead are influenced by two independent processes: 1) changes in hierarchy membership and 2) successful challenges of higher-ranking individuals. Understanding which of these processes dominates the dynamics of rank trajectories can provide insights into fitness benefits of within-sex competition. This question has yet to be examined systematically in a wide range of taxa due to the scarcity of long-term data and a lack of appropriate methodologies for distinguishing between alternative causes of rank changes over time. Here, we expand on recent work and develop a new likelihood-based Elo rating method that facilitates the systematic assessment of rank dynamics in animal social groups, even when interaction data are sparse. We apply this method to characterize long-term rank trajectories in wild eastern chimpanzees (Pan troglodytes schweinfurthii) and find remarkable sex differences in rank dynamics, indicating that females queue for social status while males actively challenge each other to rise in rank. Further, our results suggest that natal females obtain a head start in the rank queue if they avoid dispersal, with potential fitness benefits. PMID:27739527

  18. Modeling left turn queue lengths.

    Science.gov (United States)

    2011-01-01

    This guidebook provides methodologies and procedures for using incident data collected at Texas transportation management centers (TMCs) to perform two types of analysis - evaluation/planning analysis and predictive analysis. For the evaluation/plann...

  19. The ×-BMAP/G/1 Queueing Model: Queue Contents and Delay Analysis

    Directory of Open Access Journals (Sweden)

    Bart Steyaert

    2011-01-01

    Full Text Available We consider a single-server discrete-time queueing system with N sources, where each source is modelled as a correlated Markovian customer arrival process, and the customer service times are generally distributed. We focus on the analysis of the number of customers in the queue, the amount of work in the queue, and the customer delay. For each of these quantities, we will derive an expression for their steady-state probability generating function, and from these results, we derive closed-form expressions for key performance measures such as their mean value, variance, and tail distribution. A lot of emphasis is put on finding closed-form expressions for these quantities that reduce all numerical calculations to an absolute minimum.

  20. Influence of queue propagation and dissipation on route travel times

    DEFF Research Database (Denmark)

    Raovic, Nevena

    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....

  1. The Completion of Non-Steady-State Queue Model on The Queue System in Dr. Yap Eye Hospital Yogyakarta

    Science.gov (United States)

    Helmi Manggala Putri, Arum; Subekti, Retno; Binatari, Nikenasih

    2017-06-01

    Dr Yap Eye Hospital Yogyakarta is one of the most popular reference eye hospitals in Yogyakarta. There are so many patients coming from other cities and many of them are BPJS (Badan Penyelenggara Jaminan Sosial, Social Security Administrative Bodies) patients. Therefore, it causes numerous BPJS patients were in long queue at counter C of the registration section so that it needs to be analysed using queue system. Queue system analysis aims to give queue model overview and determine its effectiveness measure. The data collecting technique used in this research are by interview and observation. After getting the arrival data and the service data of BPJS patients per 5 minutes, the next steps are investigating steady-state condition, examining the Poisson distribution, determining queue models, and counting the effectiveness measure. Based on the result of data observation on Tuesday, February 16th, 2016, it shows that the queue system at counter C has (M/M/1):(GD/∞/∞) queue model. The analysis result in counter C shows that the queue system is a non-steady-state condition. Three ways to cope a non-steady-state problem on queue system are proposed in this research such as bounding the capacity of queue system, adding the servers, and doing Monte Carlo simulation. The queue system in counter C will reach steady-state if the capacity of patients is not more than 52 BPJS patients or adding one more server. By using Monte Carlo simulation, it shows that the effectiveness measure of the average waiting time for BPJS patients in counter C is 36 minutes 65 seconds. In addition, the average queue length of BPJS patients is 11 patients.

  2. Environmental management activities

    International Nuclear Information System (INIS)

    1997-01-01

    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

  3. Note on a tandem queue with delayed server release

    NARCIS (Netherlands)

    Nawijn, W.M.

    2000-01-01

    We consider a tandem queue with two stations. The first station is an $s$-server queue with Poisson arrivals and exponential service times. After terminating his service in the first station, a customer enters the second station to require service at a single server, while in the meantime he is

  4. Quasi-stationary analysis for queues with temporary overload

    NARCIS (Netherlands)

    Cheung, S.K.; Boucherie, Richardus J.; Núñez-Queija, R.

    2010-01-01

    Motivated by the high variation in transmission rates for document transfer in the Internet and file down loads from web servers, we study the buffer content in a queue with a fluctuating service rate. The fluctuations are assumed to be driven by an independent stochastic process. We allow the queue

  5. The M/G/1 queue with permanent customers

    NARCIS (Netherlands)

    Boxma, O.J.; Cohen, J.W.

    1991-01-01

    The authors examine an M/G/1 FCFS (first come, first served) queue with two types of customers: ordinary customers, who arrive according to a Poisson process, and permanent customers, who immediately return to the end of the queue after having received a service. The influence of the permanent

  6. Analysis of the asymmetrical shortest two-server queueing model

    NARCIS (Netherlands)

    J.W. Cohen

    1995-01-01

    textabstractThis study presents the analytic solution for the asymmetrical two-server queueing model with arriving customers joining the shorter queue for the case with Poisson arrivals and negative exponentially distributed service times. The bivariate generating function of the stationary joint

  7. A tandem queue with server slow-down and blocking

    NARCIS (Netherlands)

    van Foreest, N.D.; van Ommeren, Jan C.W.; Mandjes, M.R.H.; Scheinhardt, Willem R.W.

    2005-01-01

    We consider two variants of a two-station tandem network with blocking. In both variants the first server ceases to work when the queue length at the second station hits a 'blocking threshold.' In addition, in variant 2 the first server decreases its service rate when the second queue exceeds a

  8. A tandem queue with server slow-down and blocking.

    NARCIS (Netherlands)

    van Foreest, N.; van Ommeren, J.C.; Mandjes, M.R.H.; Scheinhardt, W.

    2005-01-01

    We consider two variants of a two-station tandem network with blocking. In both variants the first server ceases to work when the queue length at the second station hits a 'blocking threshold.' In addition, in variant 2 the first server decreases its service rate when the second queue exceeds a

  9. A fixed-size batch service queue with vacations

    Directory of Open Access Journals (Sweden)

    Ho Woo Lee

    1996-01-01

    Full Text Available The paper deals with batch service queues with vacations in which customers arrive according to a Poisson process. Decomposition method is used to derive the queue length distributions both for single and multiple vacation cases. The authors look at other decomposition techniques and discuss some related open problems.

  10. The impact of reneging in processor sharing queues

    NARCIS (Netherlands)

    Gromoll, H.C.; Robert, Ph.; Zwart, B.; Bakker, R.F.

    2006-01-01

    We investigate an overloaded processor sharing queue with renewal arrivals and generally distributed service times. Impatient customers may abandon the queue, or renege, before completing service. The random time representing a customer’s patience has a general distribution and may be dependent on

  11. Performance analysis of tandem queues with small buffers

    NARCIS (Netherlands)

    Vuuren, van M.; Adan, I.J.B.F.; Papadopoulos, C.T.

    2005-01-01

    In this paper we present an approximation for the performance analysis of single-server tandem queues with small buffers and generally distributed service times. The approximation is based on decomposition of the tandem queue in subsystems, the parameters of which are determined by an iterative

  12. Risk Management in Cocurricular Activities.

    Science.gov (United States)

    Webb, Edward M.

    1988-01-01

    Discusses risk management for colleges' cocurricular activities. Discusses tort liability, contributory negligence, and assumption of risk. Provides six concrete steps for managing risks responsibly and professionally: adopting an educational mission statement, assigning risk to others, establishing safety standards, training club advisors,…

  13. Emphasis: an active management model

    International Nuclear Information System (INIS)

    Gray, L.M.

    1983-01-01

    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

  14. Decomposability queueing and computer system applications

    CERN Document Server

    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

  15. Environmental Management vitrification activities

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Environmental Management vitrification activities

    International Nuclear Information System (INIS)

    Krumrine, P.H.

    1996-01-01

    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

  17. Transient queue-size distribution in a finite-capacity queueing system with server breakdowns and Bernoulli feedback

    Science.gov (United States)

    Kempa, Wojciech M.

    2017-12-01

    A finite-capacity queueing system with server breakdowns is investigated, in which successive exponentially distributed failure-free times are followed by repair periods. After the processing a customer may either rejoin the queue (feedback) with probability q, or definitely leave the system with probability 1 - q. The system of integral equations for transient queue-size distribution, conditioned by the initial level of buffer saturation, is build. The solution of the corresponding system written for Laplace transforms is found using the linear algebraic approach. The considered queueing system can be successfully used in modelling production lines with machine failures, in which the parameter q may be considered as a typical fraction of items demanding corrections. Morever, this queueing model can be applied in the analysis of real TCP/IP performance, where q stands for the fraction of packets requiring retransmission.

  18. A spectral theory approach for extreme value analysis in a tandem of fluid queues

    NARCIS (Netherlands)

    J.W. Bosman (Joost); R. Núñez Queija (Rudesindo)

    2014-01-01

    htmlabstractWe consider a model to evaluate performance of streaming media over an unreliable network. Our model consists of a tandem of two fluid queues. The first fluid queue is a Markov modulated fluid queue that models the network congestion, and the second queue represents the play-out buffer.

  19. Managing hazardous activities and substances

    International Nuclear Information System (INIS)

    Morgenroth, V.H.

    1994-01-01

    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.)

  20. Performance optimization of queueing systems with perturbation realization

    KAUST Repository

    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.

  1. Data Model Approach And Markov Chain Based Analysis Of Multi-Level Queue Scheduling

    Directory of Open Access Journals (Sweden)

    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.

  2. On finite capacity queueing systems with a general vacation policy

    Directory of Open Access Journals (Sweden)

    Jacqueline Loris-Teghem

    2000-01-01

    Full Text Available We consider a Poisson arrival queueing system with finite capacity and a general vacation policy as described in Loris-Teghem [Queueing Systems 3 (1988, 41-52]. From our previous results regarding the stationary queue length distributions immediately after a departure and at an arbitrary epoch, we derive a relation between both distributions which extends a result given in Frey and Takahashi [Operations Research Letters 21 (1997, 95-100] for the particular case of an exhaustive service multiple vacation policy.

  3. Optimal Control of a Queue With High-Low Delay Announcements: The Significance of the Queue

    Directory of Open Access Journals (Sweden)

    Alexandra Koshman-Kaz

    2015-02-01

    Full Text Available This article deals with strategic control of information in a single-server model. It considers an M/M/1 system with identical customers. There is a single cut-off number, and the level of congestion is said to be low (high if the queue length is less than (at least this value. The firm can dynamically change the admission fee according to the level of congestion. Arriving customers cannot observe the queue length, but they are informed about the current level of congestion and the admission fee. The article deals with finding the profit maximizing admission fee, using analytical and numerical methods. We observe that such a pricing regime can be used to increase the profit and the proportion of the increase relative to the single price unobservable queue is unbounded. We observe that the profit maximizing threshold is usually quite small and therefore raise a question whether there is a significant difference in profit when rather than being informed about the congestion level, customers only join the system when the server is idle. We also investigate this question considering the classical observable model.

  4. Queues with waiting time dependent service

    DEFF Research Database (Denmark)

    Bekker, R.; Koole, G. M.; Nielsen, Bo Friis

    2011-01-01

    Motivated by service levels in terms of the waiting-time distribution seen, for instance, in call centers, we consider two models for systems with a service discipline that depends on the waiting time. The first model deals with a single server that continuously adapts its service rate based...... derive steady-state waiting-time distributions for both models. The results are illustrated with numerical examples....... on the waiting time of the first customer in line. In the second model, one queue is served by a primary server which is supplemented by a secondary server when the waiting of the first customer in line exceeds a threshold. Using level crossings for the waiting-time process of the first customer in line, we...

  5. Transient analysis of a queue with queue-length dependent MAP and its application to SS7 network

    Directory of Open Access Journals (Sweden)

    Bong Dae Choi

    1999-01-01

    Full Text Available We analyze the transient behavior of a Markovian arrival queue with congestion control based on a double of thresholds, where the arrival process is a queue-length dependent Markovian arrival process. We consider Markov chain embedded at arrival epochs and derive the one-step transition probabilities. From these results, we obtain the mean delay and the loss probability of the nth arrival packet. Before we study this complex model, first we give a transient analysis of an MAP/M/1 queueing system without congestion control at arrival epochs. We apply our result to a signaling system No. 7 network with a congestion control based on thresholds.

  6. Semigroup Method on a MX/G/1 Queueing Model

    Directory of Open Access Journals (Sweden)

    Alim Mijit

    2013-01-01

    Full Text Available By using the Hille-Yosida theorem, Phillips theorem, and Fattorini theorem in functional analysis we prove that the MX/G/1 queueing model with vacation times has a unique nonnegative time-dependent solution.

  7. A unifying property for distribution-sensitive priority queues

    DEFF Research Database (Denmark)

    Elmasry, Amr Ahmed Abd Elmoneim; Farzan, Arash; Iacono, John

    2011-01-01

    , before) the last access of x and are still in the priority queue at the time when the corresponding operation is performed. Our priority queue then has both the working-set and the queueish properties; and, more strongly, it satisfies these properties in the worst-case sense. We also argue...... that these bounds are the best possible with respect to the considered measures. Moreover, we modify our priority queue to satisfy a new unifying property - the time-finger property - which encapsulates both the working-set and the queueish properties. In addition, we prove that the working-set bound......We present a priority queue that supports the operations: insert in worst-case constant time, and delete, delete-min, find-min and decrease-key on an element x in worst-case O(lg(min{wx, qx} + 2)) time, where wx (respectively, qx) is the number of elements that were accessed after (respectively...

  8. Report on dynamic speed harmonization and queue warning algorithm design.

    Science.gov (United States)

    2014-02-01

    This report provides a detailed description of the algorithms that will be used to generate harmonized recommended speeds : and queue warning information in the proposed Intelligent Network Flow Optimization (INFLO) prototype. This document : describ...

  9. Age Replacement and Service Rate Control of Stochastically Degrading Queues

    National Research Council Canada - National Science Library

    Chapin, Patrick

    2004-01-01

    This thesis considers the problem of optimally selecting a periodic replacement time for a multiserver queueing system in which each server is subject to degradation as a function of the mean service...

  10. A single-server queue with random accumulation level

    Directory of Open Access Journals (Sweden)

    Jewgeni H. Dshalalow

    1991-01-01

    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.

  11. DIRAC pilot framework and the DIRAC Workload Management System

    International Nuclear Information System (INIS)

    Casajus, Adrian; Graciani, Ricardo; Paterson, Stuart; Tsaregorodtsev, Andrei

    2010-01-01

    DIRAC, the LHCb community Grid solution, has pioneered the use of pilot jobs in the Grid. Pilot Jobs provide a homogeneous interface to an heterogeneous set of computing resources. At the same time, Pilot Jobs allow to delay the scheduling decision to the last moment, thus taking into account the precise running conditions at the resource and last moment requests to the system. The DIRAC Workload Management System provides one single scheduling mechanism for jobs with very different profiles. To achieve an overall optimisation, it organizes pending jobs in task queues, both for individual users and production activities. Task queues are created with jobs having similar requirements. Following the VO policy a priority is assigned to each task queue. Pilot submission and subsequent job matching are based on these priorities following a statistical approach.

  12. DIRAC pilot framework and the DIRAC Workload Management System

    Energy Technology Data Exchange (ETDEWEB)

    Casajus, Adrian; Graciani, Ricardo [Universitat de Barcelona (Spain); Paterson, Stuart [CERN (Switzerland); Tsaregorodtsev, Andrei, E-mail: adria@ecm.ub.e, E-mail: graciani@ecm.ub.e, E-mail: stuart.paterson@cern.c, E-mail: atsareg@in2p3.f [CPPM Marseille (France)

    2010-04-01

    DIRAC, the LHCb community Grid solution, has pioneered the use of pilot jobs in the Grid. Pilot Jobs provide a homogeneous interface to an heterogeneous set of computing resources. At the same time, Pilot Jobs allow to delay the scheduling decision to the last moment, thus taking into account the precise running conditions at the resource and last moment requests to the system. The DIRAC Workload Management System provides one single scheduling mechanism for jobs with very different profiles. To achieve an overall optimisation, it organizes pending jobs in task queues, both for individual users and production activities. Task queues are created with jobs having similar requirements. Following the VO policy a priority is assigned to each task queue. Pilot submission and subsequent job matching are based on these priorities following a statistical approach.

  13. An asymptotic analysis of closed queueing networks with branching populations

    OpenAIRE

    Bayer, N.; Coffman, E.G.; Kogan, Y.A.

    1995-01-01

    textabstractClosed queueing networks have proven to be valuable tools for system performance analysis. In this paper, we broaden the applications of such networks by incorporating populations of {em branching customers: whenever a customer completes service at some node of the network, it is replaced by N>=0 customers, each routed independently to a next node, where N has a given, possibly node-dependent branching distribution. Applications of these branching and queueing networks focus on {e...

  14. A Queueing Model for Supervisory Control of Unmanned Autonomous Vehicles

    Science.gov (United States)

    2013-09-01

    Autonomous Vehicles Joseph DiVita, PhD Robert L. Morris Maria Olinda Rodas SSC Pacific Approved...298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 09–2013 Final A Queueing Model for Supervisory Control of Unmanned Autonomous Vehicles Joseph...Mission Area: Command and Control, Queueing Model; Supervisory Control; Unmanned Autonomous Vehicles M. O. Rodas U U U U 38 (619)

  15. A queueing network model to analyze the impact of parallelization of care on patient cycle time.

    Science.gov (United States)

    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.

  16. Study of a Dynamic Cooperative Trading Queue Routing Control Scheme for Freeways and Facilities with Parallel Queues

    OpenAIRE

    Lloret-Batlle, Roger; Jayakrishnan, R.

    2018-01-01

    This article explores the coalitional stability of a new cooperative control policy for freeways and parallel queuing facilities with multiple servers. Based on predicted future delays per queue or lane, a VOT-heterogeneous population of agents can agree to switch lanes or queues and transfer payments to each other in order to minimize the total cost of the incoming platoon. The strategic interaction is captured by an n-level Stackelberg model with coalitions, while the cooperative structure ...

  17. Perbandingan Metode Simple Queues Dan Queues Tree Untuk Optimasi Manajemen Bandwidth Jaringan Komputer Di STMIK PPKIA Pradnya Paramita Malang

    OpenAIRE

    Syaifuddin, Aris; Yunus, Mahmud; Sundari, Retno

    2013-01-01

    This research resulted in a comparison between the Simple Queues method and Queues Tree using Mikrotik router that takes a case study in STMIK PPKIA PRADNYA PARAMITA MALANG has been tested to determine which method is the most optimal deal of bandwidth sharing on computer networks. After finding out where the most optimal method will be applied in STMIK PPKIA PRADNYA PARAMITA MALANG to maximize network performance and bandwidth sharing in place, the results of the study lead to the conclusion...

  18. Wait watchers: the application of a waiting list active management program in ambulatory care.

    Science.gov (United States)

    de Belvis, Antonio Giulio; Marino, Marta; Avolio, Maria; Pelone, Ferruccio; Basso, Danila; Dei Tos, Gian Antonio; Cinquetti, Sandro; Ricciardi, Walter

    2013-04-01

    This study describes and evaluates the application of a waiting list management program in ambulatory care. Waiting list active management survey (telephone call and further contact); before and after controlled trial. Local Health Trust in Veneto Region (North-East of Italy) in 2008-09. Five hundred and one people on a 554 waiting list for C Class ambulatory care diagnostic and/or clinical investigations (electrocardiography plus cardiology ambulatory consultation, eye ambulatory consultation, carotid vessels Eco-color-Doppler, legs Eco-color-Doppler or colonoscopy, respectively). Active list management program consisting of a telephonic interview on 21 items to evaluate socioeconomic features, self-perceived health status, social support, referral physician, accessibility and patients' satisfaction. A controlled before-and-after study was performed to evaluate anonymously the overall impact on patients' self-perceived quality of care. The rate of patients with deteriorating healthcare conditions; rate of dropout; interviewed degree of satisfaction about the initiative; overall impact on citizens' perceived quality of care. 95.4% patients evaluated the initiative as useful. After the intervention, patients more likely to have been targeted with the program showed a statistically significant increase in self-reported quality of care. Positive impact of the program on some dimensions of ambulatory care quality (health status, satisfaction, willingness to remain in the queue), thus confirming the outstanding value of 'not to leave people alone' and 'not to leave them feeling themselves alone' in healthcare delivery.

  19. Folding Proteins at 500 ns/hour with Work Queue.

    Science.gov (United States)

    Abdul-Wahid, Badi'; Yu, Li; Rajan, Dinesh; Feng, Haoyun; Darve, Eric; Thain, Douglas; Izaguirre, Jesús A

    2012-10-01

    Molecular modeling is a field that traditionally has large computational costs. Until recently, most simulation techniques relied on long trajectories, which inherently have poor scalability. A new class of methods is proposed that requires only a large number of short calculations, and for which minimal communication between computer nodes is required. We considered one of the more accurate variants called Accelerated Weighted Ensemble Dynamics (AWE) and for which distributed computing can be made efficient. We implemented AWE using the Work Queue framework for task management and applied it to an all atom protein model (Fip35 WW domain). We can run with excellent scalability by simultaneously utilizing heterogeneous resources from multiple computing platforms such as clouds (Amazon EC2, Microsoft Azure), dedicated clusters, grids, on multiple architectures (CPU/GPU, 32/64bit), and in a dynamic environment in which processes are regularly added or removed from the pool. This has allowed us to achieve an aggregate sampling rate of over 500 ns/hour. As a comparison, a single process typically achieves 0.1 ns/hour.

  20. Ethics in radiology: wait lists queue jumping.

    Science.gov (United States)

    Cunningham, Natalie; Reid, Lynette; MacSwain, Sarah; Clarke, James R

    2013-08-01

    Education in ethics is a requirement for all Royal College residency training programs as laid out in the General Standards of Accreditation for residency programs in Canada. The ethical challenges that face radiologists in clinical practice are often different from those that face other physicians, because the nature of the physician-patient interaction is unlike that of many other specialties. Ethics education for radiologists and radiology residents will benefit from the development of teaching materials and resources that focus on the issues that are specific to the specialty. This article is intended to serve as an educational resource for radiology training programs to facilitate teaching ethics to residents and also as a continuing medical education resource for practicing radiologists. In an environment of limited health care resources, radiologists are frequently asked to expedite imaging studies for patients and, in some respects, act as gatekeepers for specialty care. The issues of wait lists, queue jumping, and balancing the needs of individuals and society are explored from the perspective of a radiologist. Copyright © 2013 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

  1. Two Coupled Queues with Vastly Different Arrival Rates: Critical Loading Case

    Directory of Open Access Journals (Sweden)

    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.

  2. Beyond clinical priority: what matters when making operational decisions about emergency surgical queues?

    Science.gov (United States)

    Fitzgerald, Anneke; Wu, Yong

    2017-08-01

    Objective This paper describes the perceptions of operating theatre staff in Australia and The Netherlands regarding the influence of logistical or operational reasons that may affect the scheduling of unplanned surgical cases. It is proposed that logistical or operational issues can influence the priority determination of queue position of surgical cases on the emergency waiting list. Methods A questionnaire was developed and conducted in 15 hospitals across The Netherlands and Australia, targeting anaesthetists, managers, nurses and surgeons. Statistical analyses revolved around these four professional groups. Six hypotheses were then developed and tested based on the responses collected from the participants. Results There were significant differences in perceptions of logistics delay factors across different professional groups when patients were waiting for unplanned surgery. There were also significant differences among different groups when setting logistical priority factors for planning and scheduling unplanned cases. The hypotheses tests confirm these differences, and the findings concur with the paradigmatic differences mentioned in the literature. These paradigmatic differences among the four professional groups may explain some of the tensions encountered when making decisions about scheduling emergency surgical queues, and therefore should be taken into consideration for management of operating theatres. Conclusions Queue positions of patients waiting for unplanned surgery, or emergency surgery, are determined by medical clinicians according to clinicians' indication of clinical priority. However, operating theatre managers are important in facilitating smooth operations when planning for emergency surgeries. It is necessary for surgeons to understand the logistical challenges faced by managers when requesting logistical priorities for their operations. What is known about the topic? Tensions exist about the efficient use of operating theatres and

  3. Upper Bounds on Performance Measures of Heterogeneous // Queues

    Directory of Open Access Journals (Sweden)

    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.

  4. Modelling M/G/1 queueing systems with server vacations using ...

    African Journals Online (AJOL)

    Simple numerical examples are also provided to illustrate the func- ... M/G/1/N queueing systems with server vacations under a limited service discipline ...... system contents in a discrete-time non-preemptive priority queue with general service.

  5. Large Deviation Bounds for a Polling System with Two Queues and Multiple Servers

    OpenAIRE

    Wei, Fen

    2004-01-01

    In this paper, we present large deviation bounds for a discrete-time polling system consisting of two-par-allel queues and m servers. The arrival process in each queue is an arbitrary, and possibly correlated, stochastic process. Each server (serves) independently serves the two queues according to a Bernoulli service schedule. Using large deviation techniques, we analyze the tail behavior of the stationary distribution of the queue length processes, and derive upper and lower bounds of the b...

  6. Bulk input queues with quorum and multiple vacations

    Directory of Open Access Journals (Sweden)

    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.

  7. Queue and stack sorting algorithm optimization and performance analysis

    Science.gov (United States)

    Qian, Mingzhu; Wang, Xiaobao

    2018-04-01

    Sorting algorithm is one of the basic operation of a variety of software development, in data structures course specializes in all kinds of sort algorithm. The performance of the sorting algorithm is directly related to the efficiency of the software. A lot of excellent scientific research queue is constantly optimizing algorithm, algorithm efficiency better as far as possible, the author here further research queue combined with stacks of sorting algorithms, the algorithm is mainly used for alternating operation queue and stack storage properties, Thus avoiding the need for a large number of exchange or mobile operations in the traditional sort. Before the existing basis to continue research, improvement and optimization, the focus on the optimization of the time complexity of the proposed optimization and improvement, The experimental results show that the improved effectively, at the same time and the time complexity and space complexity of the algorithm, the stability study corresponding research. The improvement and optimization algorithm, improves the practicability.

  8. An introduction to queueing theory modeling and analysis in applications

    CERN Document Server

    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 ...

  9. Parallel discrete-event simulation of FCFS stochastic queueing networks

    Science.gov (United States)

    Nicol, David M.

    1988-01-01

    Physical systems are inherently parallel. Intuition suggests that simulations of these systems may be amenable to parallel execution. The parallel execution of a discrete-event simulation requires careful synchronization of processes in order to ensure the execution's correctness; this synchronization can degrade performance. Largely negative results were recently reported in a study which used a well-known synchronization method on queueing network simulations. Discussed here is a synchronization method (appointments), which has proven itself to be effective on simulations of FCFS queueing networks. The key concept behind appointments is the provision of lookahead. Lookahead is a prediction on a processor's future behavior, based on an analysis of the processor's simulation state. It is shown how lookahead can be computed for FCFS queueing network simulations, give performance data that demonstrates the method's effectiveness under moderate to heavy loads, and discuss performance tradeoffs between the quality of lookahead, and the cost of computing lookahead.

  10. Algorithm for queueing networks with multi-rate traffic

    DEFF Research Database (Denmark)

    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......In this paper we present a new algorithm for evaluating queueing networks with multi-rate traffic. The detailed state space of a node is evaluated by explicit formulæ. We consider reversible nodes with multi-rate traffic and find the state probabilities by taking advantage of local balance. Theory...... of queueing networks in general, presumes that we have product form between the nodes. Otherwise, we have the state space explosion. Even so, the detailed state space of each node may become very large because there is no product form between chains inside a node. A prerequisite for product form...

  11. Algorithm for queueing networks with multi-rate traffic

    DEFF Research Database (Denmark)

    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......In this paper we present a new algorithm for evaluating queueing networks with multi-rate traffic. The detailed state space of a node is evaluated by explicit formulæ. We consider reversible nodes with multi-rate traffic and find the state probabilities by taking advantage of local balance. Theory...... of queueing networks in general presumes that we have product form between the nodes. Other ways we have the state space explosion. Even so the detailed state space of each node may easily become very large because there is no product form between chains inside a node. A prerequisite for product form...

  12. Strategic behavior and social outcomes in a bottleneck queue

    DEFF Research Database (Denmark)

    Breinbjerg, J.; Sebald, Alexander; Østerdal, L. P.

    2016-01-01

    the 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......We theoretically and experimentally study the differential incentive effects of three well known queue disciplines in a strategic environment in which a bottleneck facility opens and impatient players decide when to arrive. For a class of three-player games, we derive equilibrium arrivals under...... 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...

  13. On response time and cycle time distributions in a two-stage cyclic queue

    NARCIS (Netherlands)

    Boxma, O.J.; Donk, P.

    1982-01-01

    We consider a two-stage closed cyclic queueing model. For the case of an exponential server at each queue we derive the joint distribution of the successive response times of a custumer at both queues, using a reversibility argument. This joint distribution turns out to have a product form. The

  14. Performance analysis of parallel identical machines with a generalized shortest queue arrival mechanism

    NARCIS (Netherlands)

    van Houtum, Geert-Jan; Adan, I.J.B.F.; Wessels, J.; Zijm, Willem H.M.

    In this paper we study a production system consisting of a group of parallel machines producing multiple job types. Each machine has its own queue and it can process a restricted set of job types only. On arrival a job joins the shortest queue among all queues capable of serving that job. Under the

  15. DecreaseKeys are Expensive for External Memory Priority Queues

    OpenAIRE

    Eenberg, Kasper; Larsen, Kasper Green; Yu, Huacheng

    2016-01-01

    One of the biggest open problems in external memory data structures is the priority queue problem with DecreaseKey operations. If only Insert and ExtractMin operations need to be supported, one can design a comparison-based priority queue performing $O((N/B)\\lg_{M/B} N)$ I/Os over a sequence of $N$ operations, where $B$ is the disk block size in number of words and $M$ is the main memory size in number of words. This matches the lower bound for comparison-based sorting and is hence optimal fo...

  16. Study on the Queue-Length Distribution in Geo/G(MWV/1/N Queue with Working Vacations

    Directory of Open Access Journals (Sweden)

    Chuanyi Luo

    2015-01-01

    Full Text Available This paper analyzes a finite buffer size discrete-time Geo/G/1/N queue with multiple working vacations and different input rate. Using supplementary variable technique and embedded Markov chain method, the queue-length distribution solution in the form of formula at arbitrary epoch is obtained. Some performance measures associated with operating cost are also discussed based on the obtained queue-length distribution. Then, several numerical experiments follow to demonstrate the effectiveness of the obtained formulae. Finally, a state-dependent operating cost function is constructed to model an express logistics service center. Regarding the service rate during working vacation as a control variable, the optimization analysis on the cost function is carried out by using parabolic method.

  17. Pricing in M/M/1 queues when cost of waiting in queue differs from cost of waiting in service

    Directory of Open Access Journals (Sweden)

    Görkem Sarıyer

    2016-11-01

    Full Text Available Service providers can adjust the entrance price to the state of the demand in real life service systems where the customers' decision to receive the service, is based on this price, state of demand and other system parameters. We analyzed service provider's short and long term pricing problems in unobservable M/M/1 queues having the rational customers, where, for customers, the unit cost of waiting in the queue is higher than unit cost of waiting in the service. We showed that waiting in the queue has a clear negative effect on customers’ utilities, hence the service provider's price values. We also showed that, in the short term, monopolistic pricing is optimal for congested systems with high server utilization levels, whereas in the long term, market capturing pricing is more profitable.

  18. A queueing system with queue length dependent service times, with applications to cell discarding in ATM networks

    Directory of Open Access Journals (Sweden)

    Doo Il Choi

    1999-01-01

    Full Text Available A queueing system (M/G1,G2/1/K is considered in which the service time of a customer entering service depends on whether the queue length, N(t, is above or below a threshold L. The arrival process is Poisson, and the general service times S1 and S2 depend on whether the queue length at the time service is initiated is

  19. The curse of the first-in-first-out queue discipline

    DEFF Research Database (Denmark)

    Platz, Trine Tornøe; Østerdal, Lars Peter Raahave

    2017-01-01

    We consider a game in which a large number of identical agents choose when to queue up at a single server after it opens. Agents are impatient for service and also incur a cost proportional to time spent in the queue. We show that the first-in–first-out queue discipline and the last......-in–first-out queue discipline both lead to a unique equilibrium arrival distribution. However, among all work-conserving queue disciplines, the first-in–first-out performs the worst in terms of equilibrium utility and welfare, while the last-in–first-out performs the best....

  20. Markovian inventory model with two parallel queues, jockeying and impatient customers

    Directory of Open Access Journals (Sweden)

    Jeganathan K.

    2016-01-01

    Full Text Available This article presents a perishable stochastic inventory system under continuous review at a service facility consisting of two parallel queues with jockeying. Each server has its own queue, and jockeying among the queues is permitted. The capacity of each queue is of finite size L. The inventory is replenished according to an (s; S inventory policy and the replenishing times are assumed to be exponentially distributed. The individual customer is issued a demanded item after a random service time, which is distributed as negative exponential. The life time of each item is assumed to be exponential. Customers arrive according to a Poisson process and on arrival; they join the shortest feasible queue. Moreover, if the inventory level is more than one and one queue is empty while in the other queue, more than one customer are waiting, then the customer who has to be received after the customer being served in that queue is transferred to the empty queue. This will prevent one server from being idle while the customers are waiting in the other queue. The waiting customer independently reneges the system after an exponentially distributed amount of time. The joint probability distribution of the inventory level, the number of customers in both queues, and the status of the server are obtained in the steady state. Some important system performance measures in the steady state are derived, so as the long-run total expected cost rate.

  1. On the control of queueing systems with aging state information

    NARCIS (Netherlands)

    Onderwater, M.; Bhulai, S.; van der Mei, R.D.

    2015-01-01

    We investigate control of a queueing system in which a component of the state space is subject to aging. The controller can choose to forward incoming queries to the system (where it needs time for processing), or respond with a previously generated response (incurring a penalty for not providing a

  2. A cooperative approach to queue allocation of indivisible objects

    NARCIS (Netherlands)

    Hamers, H.J.M.; Klijn, F.; Slikker, M.; Velzen, van B.

    2009-01-01

    We consider the allocation of a finite number of indivisible objects to the same number of agents according to an exogenously given queue. We assume that the agents collaborate in order to achieve an efficient outcome for society. We allow for side-payments and provide a method for obtaining stable

  3. A queueing model with randomized depletion of inventory

    NARCIS (Netherlands)

    Albrecher, H.-J.; Boxma, O.J.; Essifi, R.; Kuijstermans, A.C.M.

    2015-01-01

    In this paper we study an M/M/1 queue, where the server continues to work during idle periods and builds up inventory. This inventory is used for new arriving service requirements, but it is completely emptied at random epochs of a Poisson process, whose rate depends on the current level of the

  4. Departure Queue Prediction for Strategic and Tactical Surface Scheduler Integration

    Science.gov (United States)

    Zelinski, Shannon; Windhorst, Robert

    2016-01-01

    A departure metering concept to be demonstrated at Charlotte Douglas International Airport (CLT) will integrate strategic and tactical surface scheduling components to enable the respective collaborative decision making and improved efficiency benefits these two methods of scheduling provide. This study analyzes the effect of tactical scheduling on strategic scheduler predictability. Strategic queue predictions and target gate pushback times to achieve a desired queue length are compared between fast time simulations of CLT surface operations with and without tactical scheduling. The use of variable departure rates as a strategic scheduler input was shown to substantially improve queue predictions over static departure rates. With target queue length calibration, the strategic scheduler can be tuned to produce average delays within one minute of the tactical scheduler. However, root mean square differences between strategic and tactical delays were between 12 and 15 minutes due to the different methods the strategic and tactical schedulers use to predict takeoff times and generate gate pushback clearances. This demonstrates how difficult it is for the strategic scheduler to predict tactical scheduler assigned gate delays on an individual flight basis as the tactical scheduler adjusts departure sequence to accommodate arrival interactions. Strategic/tactical scheduler compatibility may be improved by providing more arrival information to the strategic scheduler and stabilizing tactical scheduler changes to runway sequence in response to arrivals.

  5. An adversarial queueing model for online server routing

    NARCIS (Netherlands)

    Bonifaci, V.

    2007-01-01

    In an online server routing problem, a vehicle or server moves in a network in order to process incoming requests at the nodes. Online server routing problems have been thoroughly studied using competitive analysis. We propose a new model for online server routing, based on adversarial queueing

  6. Single-server queues with spatially distributed arrivals

    NARCIS (Netherlands)

    Kroese, Dirk; Schmidt, Volker

    1994-01-01

    Consider a queueing system where customers arrive at a circle according to a homogeneous Poisson process. After choosing their positions on the circle, according to a uniform distribution, they wait for a single server who travels on the circle. The server's movement is modelled by a Brownian motion

  7. Sojourn-time approximations in queueing networks with feedback

    NARCIS (Netherlands)

    Gijsen, B.M.M.; van der Mei, R.D.; Engelberts, P.; van den Berg, J.L.; van Wingerden, K.M.C.

    2006-01-01

    This paper is motivated by the response-time analysis of distributed information systems, where transactions are handled by a sequence of front-end server and back-end server actions. We study sojourn times in an open queueing network with a single Processor Sharing (PS) node and an arbitrary number

  8. Sojourn time approximations in queueing networks with feedback

    NARCIS (Netherlands)

    Gijsen, B.M.M.; Mei, R.D. van der; Engelberts, P.; Berg, J.L. van den; Wingerden, K.M.C. van

    2006-01-01

    This paper is motivated by the response-time analysis of distributed information systems, where transactions are handled by a sequence of front-end server and back-end server actions. We study sojourn times in an open queueing network with a single Processor Sharing (PS) node and an arbitrary number

  9. Sojourn-time approximations in queueing networks with feedback

    NARCIS (Netherlands)

    Gijsen, B.M.M.; van der Mei, R.D.; van den Berg, Hans Leo; van Wingerden, K.M.C.

    This paper is motivated by the response-time analysis of distributed information systems, where transactions are handled by a sequence of front-end server and back-end server actions. We study sojourn times in an open queueing network with a single Processor Sharing (PS) node and an arbitrary number

  10. Customer-oriented finite perturbation analysis for queueing networks

    NARCIS (Netherlands)

    Heidergott, B.F.

    2000-01-01

    We consider queueing networks for which the performance measureJ ( ) depends on a parameter , which can be a service time parameter or a buffer size, and we are interested in sensitivity analysis of J ( ) with respect to . We introduce a new method, called customer-oriented finite perturbation

  11. Arrival first queueing networks with applications in kanban production systems

    NARCIS (Netherlands)

    Boucherie, R.J.; Chao, X.; Miyazawa, M.

    2001-01-01

    In this paper we introduce a new class of queueing networks called {\\it arrival first networks}. We characterise its transition rates and derive the relationship between arrival rules, linear partial balance equations, and product form stationary distributions. This model is motivated by production

  12. Arrival first queueing networks with applications in kanban production systems

    NARCIS (Netherlands)

    Boucherie, Richardus J.; Chao, X.; Miyazawa, M.

    2003-01-01

    In this paper, we introduce a new class of queueing networks called arrival first networks. We characterise its transition rates and derive the relationship between arrival rules, linear partial balance equations, and product form stationary distributions. This model is motivated by production

  13. Empirical Analysis of Priority on a FCFS Queue Discipline In ...

    African Journals Online (AJOL)

    Queues are virtually unavoidable phenomenon in Nigerian banking system. While banks stride to meet customers services' satisfaction, customers who do not go immediately into service must wait in line (if any). The queuing discipline in banks has been first-come-first-served (FCFS). What happen to the waiting time ...

  14. Transient error approximation in a Lévy queue

    NARCIS (Netherlands)

    Mathijsen, B.; Zwart, A.P.

    2017-01-01

    Motivated by a capacity allocation problem within a finite planning period, we conduct a transient analysis of a single-server queue with Lévy input. From a cost minimization perspective, we investigate the error induced by using stationary congestion measures as opposed to time-dependent measures.

  15. Performance analysis of manufacturing systems : queueing approximations and algorithms

    NARCIS (Netherlands)

    Vuuren, van M.

    2007-01-01

    Performance Analysis of Manufacturing Systems Queueing Approximations and Algorithms This thesis is concerned with the performance analysis of manufacturing systems. Manufacturing is the application of tools and a processing medium to the transformation of raw materials into finished goods for sale.

  16. The Supermarket Model with Bounded Queue Lengths in Equilibrium

    Science.gov (United States)

    Brightwell, Graham; Fairthorne, Marianne; Luczak, Malwina J.

    2018-04-01

    In the supermarket model, there are n queues, each with a single server. Customers arrive in a Poisson process with arrival rate λ n , where λ = λ (n) \\in (0,1) . Upon arrival, a customer selects d=d(n) servers uniformly at random, and joins the queue of a least-loaded server amongst those chosen. Service times are independent exponentially distributed random variables with mean 1. In this paper, we analyse the behaviour of the supermarket model in the regime where λ (n) = 1 - n^{-α } and d(n) = \\lfloor n^β \\rfloor , where α and β are fixed numbers in (0, 1]. For suitable pairs (α , β ) , our results imply that, in equilibrium, with probability tending to 1 as n → ∞, the proportion of queues with length equal to k = \\lceil α /β \\rceil is at least 1-2n^{-α + (k-1)β } , and there are no longer queues. We further show that the process is rapidly mixing when started in a good state, and give bounds on the speed of mixing for more general initial conditions.

  17. Estimation of the workload correlation in a Markov fluid queue

    NARCIS (Netherlands)

    Kaynar, B.; Mandjes, M.R.H.

    2013-01-01

    This paper considers a Markov fluid queue, focusing on the correlation function of the stationary workload process. A simulation-based computation technique is proposed, which relies on a coupling idea. Then an upper bound on the variance of the resulting estimator is given, which reveals how the

  18. A scheme for evaluating a local queue warning system.

    NARCIS (Netherlands)

    Botma, H. & Oei, H.-L.

    2018-01-01

    This article outlines a method of evaluating a 'local queue warning system', in principle intended only to warn drivers of unexpected congestion at known discontinuities of the road geomctry (bottleneck) and give them advisory speed indications. A prerequisite for installing this system is therefore

  19. 7. Data Structures: Lists, Queues, Stacks and Arrays

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 6. Algorithms - Data Structures: Lists, Queues, Stacks and Arrays. R K Shyamasundar. Series Article Volume 2 Issue 6 June 1997 pp 39-46. Fulltext. Click here to view fulltext PDF. Permanent link:

  20. Integrated service resource reservation using queueing networks theory

    DEFF Research Database (Denmark)

    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...

  1. Sojourn time asymptotics in processor-sharing queues

    NARCIS (Netherlands)

    Borst, S.C.; Núñez Queija, R.; Zwart, B.

    2006-01-01

    Over the past few decades, the Processor-Sharing (PS) discipline has attracted a great deal of attention in the queueing literature. While the PS paradigm emerged in the sixties as an idealization of round-robin scheduling in time-shared computer systems, it has recently captured renewed interest as

  2. Analysis of a multi-server queueing model of ABR

    NARCIS (Netherlands)

    R. Núñez Queija (Rudesindo); O.J. Boxma (Onno)

    1996-01-01

    textabstractIn this paper we present a queueing model for the performance a-na-ly-sis of ABR traffic in ATM networks. We consider a multi-channel service station with two types of customers, the first having preemptive priority over the second. The arrivals occur according to two independent Poisson

  3. Waiting time distribution in M/D/1 queueing systems

    DEFF Research Database (Denmark)

    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...

  4. Efficient Simulation of Population Overflow in Parallel Queues

    NARCIS (Netherlands)

    Nicola, V.F.; Zaburnenko, T.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 dif��?cult mathematical analysis or costly

  5. Moving toward queue operations at the Large Binocular Telescope Observatory

    Science.gov (United States)

    Edwards, Michelle L.; Summers, Doug; Astier, Joseph; Suarez Sola, Igor; Veillet, Christian; Power, Jennifer; Cardwell, Andrew; Walsh, Shane

    2016-07-01

    The Large Binocular Telescope Observatory (LBTO), a joint scientific venture between the Instituto Nazionale di Astrofisica (INAF), LBT Beteiligungsgesellschaft (LBTB), University of Arizona, Ohio State University (OSU), and the Research Corporation, is one of the newest additions to the world's collection of large optical/infrared ground-based telescopes. With its unique, twin 8.4m mirror design providing a 22.8 meter interferometric baseline and the collecting area of an 11.8m telescope, LBT has a window of opportunity to exploit its singular status as the "first" of the next generation of Extremely Large Telescopes (ELTs). Prompted by urgency to maximize scientific output during this favorable interval, LBTO recently re-evaluated its operations model and developed a new strategy that augments classical observing with queue. Aided by trained observatory staff, queue mode will allow for flexible, multi-instrument observing responsive to site conditions. Our plan is to implement a staged rollout that will provide many of the benefits of queue observing sooner rather than later - with more bells and whistles coming in future stages. In this paper, we outline LBTO's new scientific model, focusing specifically on our "lean" resourcing and development, reuse and adaptation of existing software, challenges presented from our one-of-a-kind binocular operations, and lessons learned. We also outline further stages of development and our ultimate goals for queue.

  6. Python for Scientific Computing Education: Modeling of Queueing Systems

    Directory of Open Access Journals (Sweden)

    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.

  7. Approximations for Markovian multi-class queues with preemptive priorities

    NARCIS (Netherlands)

    van der Heijden, Matthijs C.; van Harten, Aart; Sleptchenko, Andrei

    2004-01-01

    We discuss the approximation of performance measures in multi-class M/M/k queues with preemptive priorities for large problem instances (many classes and servers) using class aggregation and server reduction. We compared our approximations to exact and simulation results and found that our approach

  8. Current Chemical Risk Management Activities

    Science.gov (United States)

    EPA's existing chemicals programs address pollution prevention, risk assessment, hazard and exposure assessment and/or characterization, and risk management for chemicals substances in commercial use.

  9. Joint distribution of sojourn time and queue length in the M/G/1 queue with (in)finite capacity

    NARCIS (Netherlands)

    Boxma, O.J.

    1984-01-01

    For the M/G/1 queue we study the joint distribution of the number of customers x present immediately before an arrival epoch and of the residual service time ¿ of the customer in service at this epoch. The correlation coefficient (x, ¿) is shown to be positive (negative) when the service time

  10. Active Risk Management and Banking Stability

    NARCIS (Netherlands)

    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

  11. RUSSIAN BANK ACTIVITY STRATEGIC MANAGEMENT PROBLEMS

    Directory of Open Access Journals (Sweden)

    V. B. Pogosyan

    2011-01-01

    Full Text Available Main strategic management problems characteristic for the majority of Russian bank are: absence of systems making it possible to adapt bank activity elements to changing outer and inner business conditions; obsolete client service system; traditional liquidity and risk managementmechanisms; absence of systems of coordinating bank strategic management process participants’ interests with the banks aims. Ways of overcoming basic difficulties in bank activity strategic management are defined.

  12. Competing for jobs: labor queues and gender sorting in the hiring process.

    Science.gov (United States)

    Fernandez, Roberto M; Mors, Marie Louise

    2008-12-01

    While much research has documented the pattern and extent of sex segregation of workers once they are employed, few studies have addressed the pre-hire mechanisms that are posited to produce sex segregation in employment. While the notion of a labor queue-the rank order of the set of people that employers choose among-plays a prominent role in pre-hire accounts of job sex sorting mechanisms, few studies have examined the ways in which job candidates are sorted into labor queues. In this paper, we explore the mechanisms by which labor queues contribute to the gendering of jobs by studying the hiring process for all jobs at a call center. Being placed in a queue has a clear gendering effect on the hiring process: the sex distribution of applicants who are matched to queues and those who are rejected at this phase diverge, and among those assigned to queues, women are prevalent in queues for low pay, low status jobs. The screening process also contributes to the gendering of the population of hires at this firm. Females are more prevalent among hires than they are among candidates at initial queue assignment. Among high status jobs, however, males are more prevalent than females. Moreover, there are important wage implications associated with matching to queues. While there are large between-queue sex differences in the paid wages associated with allocation to queues, once allocated to queues the wage differences between male and female candidates are nil. Consequently, the roots of gender wage inequality in this setting lie in the initial sorting of candidates to labor queues.

  13. The Effect of Queueing Strategy on Network Traffic

    International Nuclear Information System (INIS)

    Zhang Xue-Jun; Guan Xiang-Min; Sun Deng-Feng; Tang Shao-Ting

    2013-01-01

    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)

  14. Pricing Analysis in Geo/Geo/1 Queueing System

    Directory of Open Access Journals (Sweden)

    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.

  15. Elements of queueing theory palm martingale calculus and stochastic recurrences

    CERN Document Server

    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...

  16. The queue as a social statement / Maria-Kristiina Soomre

    Index Scriptorium Estoniae

    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

  17. Large deviations and queueing networks: Methods for rate function identification

    OpenAIRE

    Atar, Rami; Dupuis, Paul

    1999-01-01

    This paper considers the problem of rate function identification for multidimensional queueing models with feedback. A set of techniques are introduced which allow this identification when the model possesses certain structural properties. The main tools used are representation formulas for exponential integrals, weak convergence methods, and the regularity properties of associated Skorokhod Problems. Two examples are treated as special cases of the general theory: the classical Jackson netwo...

  18. The asymptotic variance of departures in critically loaded queues

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Mandjes, M.R.H.; Nazarathy, Y.; Whitt, W.

    2011-01-01

    We consider the asymptotic variance of the departure counting process D(t) of the GI/G/1 queue; D(t) denotes the number of departures up to time t. We focus on the case where the system load ϱ equals 1, and prove that the asymptotic variance rate satisfies limt→∞varD(t) / t = λ(1 - 2 / π)(ca2 +

  19. A diffusion model for two parallel queues with processor sharing: transient behavior and asymptotics

    Directory of Open Access Journals (Sweden)

    Charles Knessl

    1999-01-01

    Full Text Available We consider two identical, parallel M/M/1 queues. Both queues are fed by a Poisson arrival stream of rate λ and have service rates equal to μ. When both queues are non-empty, the two systems behave independently of each other. However, when one of the queues becomes empty, the corresponding server helps in the other queue. This is called head-of-the-line processor sharing. We study this model in the heavy traffic limit, where ρ=λ/μ→1. We formulate the heavy traffic diffusion approximation and explicitly compute the time-dependent probability of the diffusion approximation to the joint queue length process. We then evaluate the solution asymptotically for large values of space and/or time. This leads to simple expressions that show how the process achieves its stead state and other transient aspects.

  20. Organizational Actively Management for Opportunity Hunting

    Directory of Open Access Journals (Sweden)

    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.

  1. Activity versus outcome maximization in time management.

    Science.gov (United States)

    Malkoc, Selin A; Tonietto, Gabriela N

    2018-04-30

    Feeling time-pressed has become ubiquitous. Time management strategies have emerged to help individuals fit in more of their desired and necessary activities. We provide a review of these strategies. In doing so, we distinguish between two, often competing, motives people have in managing their time: activity maximization and outcome maximization. The emerging literature points to an important dilemma: a given strategy that maximizes the number of activities might be detrimental to outcome maximization. We discuss such factors that might hinder performance in work tasks and enjoyment in leisure tasks. Finally, we provide theoretically grounded recommendations that can help balance these two important goals in time management. Published by Elsevier Ltd.

  2. Queueing models for token and slotted ring networks. Thesis

    Science.gov (United States)

    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.

  3. Queueing network model for obstetric patient flow in a hospital.

    Science.gov (United States)

    Takagi, Hideaki; Kanai, Yuta; Misue, Kazuo

    2016-03-03

    A queueing network is used to model the flow of patients in a hospital using the observed admission rate of patients and the histogram for the length of stay for patients in each ward. A complete log of orders for every movement of all patients from room to room covering two years was provided to us by the Medical Information Department of the University of Tsukuba Hospital in Japan. We focused on obstetric patients, who are generally hospitalized at random times throughout the year, and we analyzed the patient flow probabilistically. On admission, each obstetric patient is assigned to a bed in one of the two wards: one for normal delivery and the other for high-risk delivery. Then, the patient may be transferred between the two wards before discharge. We confirm Little's law of queueing theory for the patient flow in each ward. Next, we propose a new network model of M/G/ ∞ and M/M/ m queues to represent the flow of these patients, which is used to predict the probability distribution for the number of patients staying in each ward at the nightly census time. Although our model is a very rough and simplistic approximation of the real patient flow, the predicted probability distribution shows good agreement with the observed data. The proposed method can be used for capacity planning of hospital wards to predict future patient load in each ward.

  4. On the busy period of discretized GI/GI/infinity queue

    International Nuclear Information System (INIS)

    Dvurecenskij, A.; Ososkov, G.A.

    1982-01-01

    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

  5. Markov-modulated infinite-server queues driven by a common background process

    OpenAIRE

    Mandjes , Michel; De Turck , Koen

    2016-01-01

    International audience; This paper studies a system with multiple infinite-server queues which are modulated by a common background process. If this background process, being modeled as a finite-state continuous-time Markov chain, is in state j, then the arrival rate into the i-th queue is λi,j, whereas the service times of customers present in this queue are exponentially distributed with mean µ −1 i,j ; at each of the individual queues all customers present are served in parallel (thus refl...

  6. Sharpening the Arithmetic of Active Management

    DEFF Research Database (Denmark)

    Pedersen, Lasse Heje

    2018-01-01

    I challenge William F. Sharpe's famous equality that "before costs, the return on the average actively managed dollar will equal the return on the average passively managed dollar." This equality is based on the implicit assumption that the market portfolio never changes, which does not hold....... Passive investing also plays a useful economic role: creating low-cost access to markets....

  7. Activity Recognition for Personal Time Management

    Science.gov (United States)

    Prekopcsák, Zoltán; Soha, Sugárka; Henk, Tamás; Gáspár-Papanek, Csaba

    We describe an accelerometer based activity recognition system for mobile phones with a special focus on personal time management. We compare several data mining algorithms for the automatic recognition task in the case of single user and multiuser scenario, and improve accuracy with heuristics and advanced data mining methods. The results show that daily activities can be recognized with high accuracy and the integration with the RescueTime software can give good insights for personal time management.

  8. Message passing with parallel queue traversal

    Science.gov (United States)

    Underwood, Keith D [Albuquerque, NM; Brightwell, Ronald B [Albuquerque, NM; Hemmert, K Scott [Albuquerque, NM

    2012-05-01

    In message passing implementations, associative matching structures are used to permit list entries to be searched in parallel fashion, thereby avoiding the delay of linear list traversal. List management capabilities are provided to support list entry turnover semantics and priority ordering semantics.

  9. Queue Length and Server Content Distribution in an Infinite-Buffer Batch-Service Queue with Batch-Size-Dependent Service

    Directory of Open Access Journals (Sweden)

    U. C. Gupta

    2015-01-01

    Full Text Available We analyze an infinite-buffer batch-size-dependent batch-service queue with Poisson arrival and arbitrarily distributed service time. Using supplementary variable technique, we derive a bivariate probability generating function from which the joint distribution of queue and server content at departure epoch of a batch is extracted and presented in terms of roots of the characteristic equation. We also obtain the joint distribution of queue and server content at arbitrary epoch. Finally, the utility of analytical results is demonstrated by the inclusion of some numerical examples which also includes the investigation of multiple zeros.

  10. Convergence of a Queueing System in Heavy Traffic with General Abandonment Distributions

    Science.gov (United States)

    2010-10-08

    331–391, 2005. [4] R. Atar . Scheduling control for queueing systems with many servers: asymptotic optimality in heavy traffic. Ann. Appl. Probab., 15...4):2606–2650, 2005. 37 [5] R. Atar , A. Mandelbaum, and M. I. Reiman. Scheduling a multi class queue with many exponential servers: asymptotic

  11. An M/G/1 queue with multiple types of feedback and gated vacations

    NARCIS (Netherlands)

    O.J. Boxma (Onno); U. Yechiali

    1995-01-01

    textabstractThis paper considers a single-server queue with Poisson arrivals and multiple customer feedbacks. If the first service attempt of a newly arriving customer is not successful, he returns to the end of the queue for another service attempt, with a different service time distribution. He

  12. Matrix-geometric analysis of the shortest queue problem with threshold jockeying

    NARCIS (Netherlands)

    Zijm, Willem H.M.; Adan, I.J.B.F.; Wessels, J.

    1993-01-01

    In this paper we study a system consisting of c parallel servers with possibly different service rates. Jobs arrive according to a Poisson stream and generate an exponentially distributed workload. An arriving job joins the shortest queue, where in case of multiple shortest queues, one of these

  13. A single-server queue with batch arrivals and semi-Markov services

    NARCIS (Netherlands)

    Abhishek,; Boon, M.A.A.; Boxma, O.J.; Núñez-Queija, R.

    2017-01-01

    We investigate the transient and stationary queue length distributions of a class of service systems with correlated service times. The classical (Formula presented.) queue with semi-Markov service times is the most prominent example in this class and serves as a vehicle to display our results. The

  14. Analysis of an M/G/1 queue with customer impatience and an adaptive arrival process

    NARCIS (Netherlands)

    Boxma, O.J.; Prabhu, B.J.

    2009-01-01

    We study an M/G/1 queue with impatience and an adaptive arrival process. The rate of the arrival process changes according to whether an incoming customer is accepted or rejected. We analyse two different models for impatience : (i) based on workload, and (ii) based on queue length. For the

  15. Slowdown in the $M/M/1$ discriminatory processor-sharing queue

    NARCIS (Netherlands)

    Cheung, S.K.; Kim, Bara; Kim, Jeongsim

    2008-01-01

    We consider a queue with multiple K job classes, Poisson arrivals, and exponentially distributed required service times in which a single processor serves according to the discriminatory processor-sharing (DPS) discipline. For this queue, we obtain the first and second moments of the slowdown, which

  16. Sojourn time tails in the single server queue with heavy-tailed service times

    NARCIS (Netherlands)

    Boxma, O.J.; Denisov, D.E.

    2009-01-01

    We consider the GI/GI/1 queue with regularly varying service requirement distribution of index -a. It is well known that, in the M/G/1 FCFS queue, the sojourn time distribution is also regularly varying, of index 1 - a, whereas in the case of LCFS or Processor Sharing, the sojourn time distribution

  17. Routing policies for a partially observable two-server queueing system

    NARCIS (Netherlands)

    Ellens, W.; Kovács, P.; Núñez-Queija, R.; Berg, H. van den

    2015-01-01

    We consider a queueing system controlled by decisions based on partial state information. The motivation for this work stems from road traffic, in which drivers may, or may not, be subscribed to a smartphone application for dynamic route planning. Our model consists of two queues with independent

  18. Routing policies for a partially observable two-server queueing system

    NARCIS (Netherlands)

    W. Ellens; P. Kovacs; J.L. van den Berg (Hans); R. Núñez Queija (Rudesindo); A. Busic; M. Gribaudo; P. Reinecke

    2015-01-01

    htmlabstractWe consider a queueing system controlled by decisions based on partial state information. The motivation for this work stems from road traffic, in which drivers may, or may not, be subscribed to a smartphone application for dynamic route planning. Our model consists of two queues

  19. Waiting-time approximations in multi-queue systems with cyclic service

    NARCIS (Netherlands)

    Boxma, O.J.; Meister, B.W.

    1987-01-01

    This study is devoted to mean waiting-time approximations in a single-server multi-queue model with cyclic service and zero switching times of the server between consecutive queues. Two different service disciplines are considered: exhaustive service and (ordinary cyclic) nonexhaustive service. For

  20. Global and local asymptotics for the busy period of an M/G/1 queue

    NARCIS (Netherlands)

    Denisov, D.E.; Shneer, V.

    2010-01-01

    We consider an M/G/1 queue with subexponential service times. We give a simple derivation of the global and local asymptotics for the busy period. Our analysis relies on the explicit formula for the joint distribution for the number of customers and the length of the busy period of an M/G/1 queue.

  1. Sojourn time tails in the single server queue with heavy-tailed service times

    NARCIS (Netherlands)

    Boxma, O.J.; Denisov, D.E.

    2011-01-01

    We consider the GI/GI/1 queue with regularly varying service requirement distribution of index -a. It is well known that, in the M/G/1 FCFS queue, the sojourn time distribution is also regularly varying, of index 1-a, whereas in the case of LCFS or Processor Sharing, the sojourn time distribution is

  2. Analysis of the asymmetric shortest queue problem : part 2: numerical analysis

    NARCIS (Netherlands)

    Adan, I.J.B.F.; Wessels, J.; Zijm, W.H.M.

    1990-01-01

    In this paper we study a system consisting of two parallel servers with different service rates. Jobs arrive according to a Poisson stream and generate an exponentially distributed workload. On arrival a job joins the shortest queue and in case both queues have equal lengths, he joins the first

  3. Analysis of the asymmetric shortest queue problem : Part 1: theoretical analysis

    NARCIS (Netherlands)

    Adan, I.J.B.F.; Wessels, J.; Zijm, W.H.M.

    1990-01-01

    In this paper we study a system consisting of two parallel servers with different service rates. Jobs arrive according to a Poisson stream and generate an exponentially distributed workload. On arrival a job joins the shortest queue and in case both queues have equal lengths. be joins the first

  4. Approximations for the waiting time distribution in an M/G/c priority queue

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Alvarez, Elisa; van der Heijden, Matthijs C.

    2013-01-01

    We investigate the use of priority mechanisms when assigning service engineers to customers as a tool for service differentiation. To this end, we analyze a non-preemptive M/G/c priority queue with various customer classes. For this queue, we present various accurate and fast methods to estimate the

  5. Efficient Heuristics for the Simulation of Buffer Overflow in Series and Parallel Queueing Networks

    NARCIS (Netherlands)

    Nicola, V.F.; Zaburnenko, T.S.

    2006-01-01

    In this paper we propose state-dependent importance sampling heuristics to estimate the probability of population overflow in Markovian networks of series and parallel queues. These heuristics capture state-dependence along the boundaries (when one or more queues are empty) which is critical for

  6. Queue balancing of load and expedition service in a cement industry in Brazil

    Directory of Open Access Journals (Sweden)

    David Custódio de Sena

    2013-11-01

    Full Text Available The load and weight process in a cement industry is one of logistic step that shows the biggest time of occurrence, increasing the queues. This study aims to do a scenarios to solve this queue problem. This way, it pretends to find an better resources distribuition.

  7. Medical ethics and new public management in Sweden.

    Science.gov (United States)

    Hansson, Sven Ove

    2014-07-01

    In order to shorten queues to healthcare, the Swedish government has introduced a yearly "queue billion" that is paid out to the county councils in proportion to how successful they are in reducing queues. However, only the queues for first visits are covered. Evidence has accumulated that queues for return visits have become longer. This affects the chronically and severely ill. Swedish physicians, and the Swedish Medical Association, have strongly criticized the queue billion and have claimed that it conflicts with medical ethics. Instead they demand that their professional judgments on priority setting and medical urgency be respected. This discussion provides an interesting illustration of some of the limitations of new public management and also more generally of the complicated relationships between medical ethics and public policy.

  8. A Parallel Priority Queue with Constant Time Operations

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Träff, Jesper Larsson; Zaroliagis, Christos D.

    1998-01-01

    We present a parallel priority queue that supports the following operations in constant time:parallel insertionof a sequence of elements ordered according to key,parallel decrease keyfor a sequence of elements ordered according to key,deletion of the minimum key element, anddeletion of an arbitrary...... application is a parallel implementation of Dijkstra's algorithm for the single-source shortest path problem, which runs inO(n) time andO(mlogn) work on a CREW PRAM on graphs withnvertices andmedges. This is a logarithmic factor improvement in the running time compared with previous approaches....

  9. Stochastic network optimization with application to communication and queueing systems

    CERN Document Server

    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

  10. Two coupled Lévy queues with independent input

    OpenAIRE

    Jevgenijs Ivanovs; Onno Boxma

    2014-01-01

    We consider a pair of coupled queues driven by independent spectrally-positive Lévy processes. With respect to the bi-variate workload process this framework includes both the coupled processor model and the two-server fluid network with independent Lévy inputs. We identify the joint transform of the stationary workload distribution in terms of Wiener-Hopf factors corresponding to two auxiliary Lévy processes with explicit Laplace exponents. We reinterpret and extend the ideas of Cohen and Bo...

  11. Correlations in Output and Overflow Traffic Processes in Simple Queues

    Directory of Open Access Journals (Sweden)

    Don McNickle

    2007-01-01

    Full Text Available We consider some simple Markov and Erlang queues with limited storage space. Although the departure processes from some such systems are known to be Poisson, they actually consist of the superposition of two complex correlated processes, the overflow process and the output process. We measure the cross-correlation between the counting processes for these two processes. It turns out that this can be positive, negative, or even zero (without implying independence. The models suggest some general principles on how big these correlations are, and when they are important. This may suggest when renewal or moment approximations to similar processes will be successful, and when they will not.

  12. On the Nonsymmetric Longer Queue Model: Joint Distribution, Asymptotic Properties, and Heavy Traffic Limits

    Directory of Open Access Journals (Sweden)

    Charles Knessl

    2013-01-01

    Full Text Available We consider two parallel queues, each with independent Poisson arrival rates, that are tended by a single server. The exponential server devotes all of its capacity to the longer of the queues. If both queues are of equal length, the server devotes ν of its capacity to the first queue and the remaining 1−ν to the second. We obtain exact integral representations for the joint probability distribution of the number of customers in this two-node network. Then we evaluate this distribution in various asymptotic limits, such as large numbers of customers in either/both of the queues, light traffic where arrivals are infrequent, and heavy traffic where the system is nearly unstable.

  13. Request queues for interactive clients in a shared file system of a parallel computing system

    Science.gov (United States)

    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.

  14. Convolution Model of a Queueing System with the cFIFO Service Discipline

    Directory of Open Access Journals (Sweden)

    Sławomir Hanczewski

    2016-01-01

    Full Text Available This article presents an approximate convolution model of a multiservice queueing system with the continuous FIFO (cFIFO service discipline. The model makes it possible to service calls sequentially with variable bit rate, determined by unoccupied (free resources of the multiservice server. As compared to the FIFO discipline, the cFIFO queue utilizes the resources of a multiservice server more effectively. The assumption in the model is that the queueing system is offered a mixture of independent multiservice Bernoulli-Poisson-Pascal (BPP call streams. The article also discusses the results of modelling a number of queueing systems to which different, non-Poissonian, call streams are offered. To verify the accuracy of the model, the results of the analytical calculations are compared with the results of simulation experiments for a number of selected queueing systems. The study has confirmed the accuracy of all adopted theoretical assumptions for the proposed analytical model.

  15. New Approach for Finding Basic Performance Measures of Single Server Queue

    Directory of Open Access Journals (Sweden)

    Siew Khew Koh

    2014-01-01

    Full Text Available Consider the single server queue in which the system capacity is infinite and the customers are served on a first come, first served basis. Suppose the probability density function f(t and the cumulative distribution function F(t of the interarrival time are such that the rate f(t/1-F(t tends to a constant as t→∞, and the rate computed from the distribution of the service time tends to another constant. When the queue is in a stationary state, we derive a set of equations for the probabilities of the queue length and the states of the arrival and service processes. Solving the equations, we obtain approximate results for the stationary probabilities which can be used to obtain the stationary queue length distribution and waiting time distribution of a customer who arrives when the queue is in the stationary state.

  16. A survey on queues in machining system: Progress from 2010 to 2017

    Directory of Open Access Journals (Sweden)

    Shekhar C.

    2017-01-01

    Full Text Available The aim of the present article is to give a historical survey of some important research works related to queues in machining system since 2010. Queues of failed machines in machine repairing problem occur due to the failure of machines at random in the manufacturing industries, where different jobs are performed on machining stations. Machines are subject to failure what may result in significant loss of production, revenue, or goodwill. In addition to the references on queues in machining system, which is also called `Machine Repair Problem' (MRP or `Machine Interference Problem' (MIP, a meticulous list of books and survey papers is also prepared so as to provide a detailed catalog for understanding the research in queueing domain. We have classified the relevant literature according to a year of publishing, methodological, and modeling aspects. The author(s hope that this survey paper could be of help to learners contemplating research on queueing domain.

  17. Worst-case efficient external-memory priority queues

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Katajainen, Jyrki

    1998-01-01

    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 ≥ clogM/B N...

  18. Multiserver Queue with Guard Channel for Priority and Retrial Customers

    Directory of Open Access Journals (Sweden)

    Kazuki Kajiwara

    2016-01-01

    Full Text Available This paper considers a retrial queueing model where a group of guard channels is reserved for priority and retrial customers. Priority and normal customers arrive at the system according to two distinct Poisson processes. Priority customers are accepted if there is an idle channel upon arrival while normal customers are accepted if and only if the number of idle channels is larger than the number of guard channels. Blocked customers (priority or normal join a virtual orbit and repeat their attempts in a later time. Customers from the orbit (retrial customers are accepted if there is an idle channel available upon arrival. We formulate the queueing system using a level dependent quasi-birth-and-death (QBD process. We obtain a Taylor series expansion for the nonzero elements of the rate matrices of the level dependent QBD process. Using the expansion results, we obtain an asymptotic upper bound for the joint stationary distribution of the number of busy channels and that of customers in the orbit. Furthermore, we develop an efficient numerical algorithm to calculate the joint stationary distribution.

  19. Proposal for optimal placement platform of bikes using queueing networks.

    Science.gov (United States)

    Mizuno, Shinya; Iwamoto, Shogo; Seki, Mutsumi; Yamaki, Naokazu

    2016-01-01

    In recent social experiments, rental motorbikes and rental bicycles have been arranged at nodes, and environments where users can ride these bikes have been improved. When people borrow bikes, they return them to nearby nodes. Some experiments have been conducted using the models of Hamachari of Yokohama, the Niigata Rental Cycle, and Bicing. However, from these experiments, the effectiveness of distributing bikes was unclear, and many models were discontinued midway. Thus, we need to consider whether these models are effectively designed to represent the distribution system. Therefore, we construct a model to arrange the nodes for distributing bikes using a queueing network. To adopt realistic values for our model, we use the Google Maps application program interface. Thus, we can easily obtain values of distance and transit time between nodes in various places in the world. Moreover, we apply the distribution of a population to a gravity model and we compute the effective transition probability for this queueing network. If the arrangement of the nodes and number of bikes at each node is known, we can precisely design the system. We illustrate our system using convenience stores as nodes and optimize the node configuration. As a result, we can optimize simultaneously the number of nodes, node places, and number of bikes for each node, and we can construct a base for a rental cycle business to use our system.

  20. Upper Bound for Queue length in Regulated Burst Service Scheduling

    Directory of Open Access Journals (Sweden)

    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.

  1. Queueing-Based Synchronization and Entrainment for Synthetic Gene Oscillators

    Science.gov (United States)

    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.

  2. Two parallel finite queues with simultaneous services and Markovian arrivals

    Directory of Open Access Journals (Sweden)

    S. R. Chakravarthy

    1997-01-01

    Full Text Available In this paper, we consider a finite capacity single server queueing model with two buffers, A and B, of sizes K and N respectively. Messages arrive one at a time according to a Markovian arrival process. Messages that arrive at buffer A are of a different type from the messages that arrive at buffer B. Messages are processed according to the following rules: 1. When buffer A(B has a message and buffer B(A is empty, then one message from A(B is processed by the server. 2. When both buffers, A and B, have messages, then two messages, one from A and one from B, are processed simultaneously by the server. The service times are assumed to be exponentially distributed with parameters that may depend on the type of service. This queueing model is studied as a Markov process with a large state space and efficient algorithmic procedures for computing various system performance measures are given. Some numerical examples are discussed.

  3. Managing Brain Extracellular K(+) during Neuronal Activity

    DEFF Research Database (Denmark)

    Larsen, Brian Roland; Stoica, Anca; MacAulay, Nanna

    2016-01-01

    characteristics required to fulfill their distinct physiological roles in clearance of K(+) from the extracellular space in the face of neuronal activity. Understanding the nature, impact and effects of the various Na(+)/K(+)-ATPase isoform combinations in K(+) management in the central nervous system might...... understanding of the pathological events occurring during disease....

  4. Sharpening the Arithmetic of Active Management

    DEFF Research Database (Denmark)

    Pedersen, Lasse Heje

    2018-01-01

    in the real world because new shares are issued, others are repurchased, and indexes are reconstituted--so even "passive" investors must regularly trade. Therefore, active managers can be worth positive fees in aggregate, allowing them to play an important economic role: helping allocate resources efficiently...

  5. Jose Cabrera NPP severe accident management activities

    International Nuclear Information System (INIS)

    Blanco, J.; Almeida, P.; Saiz, J.; Sastre, J.L.; Delgado, R.

    1998-01-01

    To prepare a common acting plan with respect to Severe Accident Management, in 1994 was founded the severe accident management ''ad-hoc'' working group from the Spanish Westinghouse PWR Nuclear Power Plant Owners Group. In this group actively collaborated the Jose Cabrera NPP Training Centre and the Department of Nuclear Engineering of UNION FENOSA. From this moment, Jose Cabrera NPP began the planning of its specific Severe Accident Management Program, which main point are Severe Accident Management Guidelines (SAMG). To elaborate this guidelines, the Spanish translation of Westinghouse Owners Group (WOG) Severe Accident Management Guidelines were considered the reference documents. The implementation of this Guidelines to Jose Cabrera NPP started on January 1997. Once the specific guidelines have been implemented to the plant, training activities for the personnel involved in severe accident issues will be developed. To prepare the training exercises MAAP4 code will be used, and with this intention, a specific Jose Cabrera NPP MAAP-GRAAPH screen has been developed. Furthermore, a wide selection of MAAP input files for the simulation of different scenarios and accidental events is available. (Author)

  6. A Taylor Series Approach for Service-Coupled Queueing Systems with Intermediate Load

    Directory of Open Access Journals (Sweden)

    Ekaterina Evdokimova

    2017-01-01

    Full Text Available This paper investigates the performance of a queueing model with multiple finite queues and a single server. Departures from the queues are synchronised or coupled which means that a service completion leads to a departure in every queue and that service is temporarily interrupted whenever any of the queues is empty. We focus on the numerical analysis of this queueing model in a Markovian setting: the arrivals in the different queues constitute Poisson processes and the service times are exponentially distributed. Taking into account the state space explosion problem associated with multidimensional Markov processes, we calculate the terms in the series expansion in the service rate of the stationary distribution of the Markov chain as well as various performance measures when the system is (i overloaded and (ii under intermediate load. Our numerical results reveal that, by calculating the series expansions of performance measures around a few service rates, we get accurate estimates of various performance measures once the load is above 40% to 50%.

  7. Steps in Designing Queue and Interview Process using Information System: A Case of Re-registration of New Students in Universitas Negeri Makassar

    Directory of Open Access Journals (Sweden)

    Ansari Saleh Ahmar

    2016-06-01

    Full Text Available Universitas Negeri Makassar (UNM have a number of prospective students is quite a lot. Based on data released by the BAPSI UNM (2015 that the data student candidates of UNM who passed the selection with SNMPTN SBMPTN selection as 3,791 people. If the prospective graduate students interviewed are normally it will take a long time and will certainly make students uncomfortable. Therefore it is necessary design an information systems to solving this problem. This research aim to develop an information system to facilitate the process queue. The method used in this research is to use the three stages in the Software Development Life Cycle method namely Initiation Phase, Development/Acquisition Phase, and Implementation Phase. This information system development using PHP and CodeIgniter as a its framework. This design results will be obtained an queues and interviews information system that can be used to manage the queue and interview data. By implementing this system, it potentially reduce time to wait and the process of managing results of interviews can be obtained directly without a process of inputting interview repeat if done manually.

  8. Sojourn time distributions in a Markovian G-queue with batch arrival and batch removal

    Directory of Open Access Journals (Sweden)

    Yang Woo Shin

    1999-01-01

    Full Text Available 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 first passage time arguments for Markov chains.

  9. Strategies for a centralized single product multiclass M/G/1 make-to-stock queue

    OpenAIRE

    Abouee-Mehrizi, Hossein; Balcıoğlu, Ahmet Barış; Balcioglu, Ahmet Baris; Baron, Opher

    2012-01-01

    Make-to-stock queues are typically investigated in the M/M/1 settings. For centralized single-item systems with backlogs, the multilevel rationing (MR) policy is established as optimal and the strict priority (SP) policy is a practical compromise, balancing cost and ease of implementation. However, the optimal policy is unknown when service time is general, i.e., for M/G/1 queues. Dynamic programming, the tool commonly used to investigate the MR policy in make-to-stock queues, is less practic...

  10. Managing CSCL Activity through networking models

    Directory of Open Access Journals (Sweden)

    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.

  11. Analysis of DOE international environmental management activities

    Energy Technology Data Exchange (ETDEWEB)

    Ragaini, R.C.

    1995-09-01

    The Department of Energy`s (DOE) Strategic Plan (April 1994) states that DOE`s long-term vision includes world leadership in environmental restoration and waste management activities. The activities of the DOE Office of Environmental Management (EM) can play a key role in DOE`s goals of maintaining U.S. global competitiveness and ensuring the continuation of a world class science and technology community. DOE`s interest in attaining these goals stems partly from its participation in organizations like the Trade Policy Coordinating Committee (TPCC), with its National Environmental Export Promotion Strategy, which seeks to strengthen U.S. competitiveness and the building of public-private partnerships as part of U.S. industrial policy. The International Interactions Field Office task will build a communication network which will facilitate the efficient and effective communication between DOE Headquarters, Field Offices, and contractors. Under this network, Headquarters will provide the Field Offices with information on the Administration`s policies and activities (such as the DOE Strategic Plan), interagency activities, as well as relevant information from other field offices. Lawrence Livermore National Laboratory (LLNL) will, in turn, provide Headquarters with information on various international activities which, when appropriate, will be included in reports to groups like the TPCC and the EM Focus Areas. This task provides for the collection, review, and analysis of information on the more significant international environmental restoration and waste management initiatives and activities which have been used or are being considered at LLNL. Information gathering will focus on efforts and accomplishments in meeting the challenges of providing timely and cost effective cleanup of its environmentally damaged sites and facilities, especially through international technical exchanges and/or the implementation of foreign-development technologies.

  12. Efficient priority queueing routing strategy on networks of mobile agents

    Science.gov (United States)

    Wu, Gan-Hua; Yang, Hui-Jie; Pan, Jia-Hui

    2018-03-01

    As a consequence of their practical implications for communications networks, traffic dynamics on complex networks have recently captivated researchers. Previous routing strategies for improving transport efficiency have paid little attention to the orders in which the packets should be forwarded, just simply used first-in-first-out queue discipline. Here, we apply a priority queuing discipline and propose a shortest-distance-first routing strategy on networks of mobile agents. Numerical experiments reveal that the proposed scheme remarkably improves both the network throughput and the packet arrival rate and reduces both the average traveling time and the rate of waiting time to traveling time. Moreover, we find that the network capacity increases with an increase in both the communication radius and the number of agents. Our work may be helpful for the design of routing strategies on networks of mobile agents.

  13. Film traffic queueing model for the DUMC radiology department

    International Nuclear Information System (INIS)

    Humphrey, L.M.; Ravin, C.E.

    1988-01-01

    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

  14. Ultrasound waiting lists: rational queue or extended capacity?

    Science.gov (United States)

    Brasted, Christopher

    2008-06-01

    The features and issues regarding clinical waiting lists in general and general ultrasound waiting lists in particular are reviewed, and operational aspects of providing a general ultrasound service are also discussed. A case study is presented describing a service improvement intervention in a UK NHS hospital's ultrasound department, from which arises requirements for a predictive planning model for an ultrasound waiting list. In the course of this, it becomes apparent that a booking system is a more appropriate way of describing the waiting list than a conventional queue. Distinctive features are identified from the literature and the case study as the basis for a predictive model, and a discrete event simulation model is presented which incorporates the distinctive features.

  15. Analysis of a multi-server queueing model of ABR

    Directory of Open Access Journals (Sweden)

    R. Núñez-Queija

    1998-01-01

    Full Text Available In this paper we present a queueing model for the performance analysis of Available Bit Rate (ABR traffic in Asynchronous Transfer Mode (ATM networks. We consider a multi-channel service station with two types of customers, denoted by high priority and low priority customers. In principle, high priority customers have preemptive priority over low priority customers, except on a fixed number of channels that are reserved for low priority traffic. The arrivals occur according to two independent Poisson processes, and service times are assumed to be exponentially distributed. Each high priority customer requires a single server, whereas low priority customers are served in processor sharing fashion. We derive the joint distribution of the numbers of customers (of both types in the system in steady state. Numerical results illustrate the effect of high priority traffic on the service performance of low priority traffic.

  16. IAEA activities on steam generator life management

    International Nuclear Information System (INIS)

    Gueorguiev, B.; Lyssakov, V.; Trampus, P.

    2002-01-01

    The International Atomic Energy Agency (IAEA) carries out a set of activities in the field of Nuclear Power Plant (NPP) life management. Main activities within this area are implemented through the Technical Working Group on Life Management of NPPs, and mostly concentrated on studies of understanding mechanisms of degradation and their monitoring, optimisation of maintenance management, economic aspects, proven practices of and approaches to plant life management including decommissioning. The paper covers two ongoing activities related to steam generator life management: the International Database on NPP Steam Generators and the Co-ordinated Research Project on Verification of WWER Steam Generator Tube Integrity (WWER is the Russian designed PWR). The lifetime assessment of main components relies on an ability to assess their condition and predict future degradation trends, which to a large extent is dependent on the availability of relevant data. Effective management of ageing and degradation processes requires a large amount of data. Several years ago the IAEA started to work on the International Database on NPP Life Management. This is a multi-module database consisting of modules such as reactor pressure vessels materials, piping, steam generators, and concrete structures. At present the work on pressure vessel materials, on piping as well as on steam generator is completed. The paper will present the concept and structure of the steam generator module of the database. In countries operating WWER NPPs, there are big differences in the eddy current inspection strategy and practice as well as in the approach to steam generator heat exchanger tube structural integrity assessment. Responding to the need for a co-ordinated research to compare eddy current testing results with destructive testing using pulled out tubes from WWER steam generators, the IAEA launched this project. The main objectives of the project are to summarise the operating experiences of WWER

  17. Management of synchronized network activity by highly active neurons

    International Nuclear Information System (INIS)

    Shein, Mark; Raichman, Nadav; Ben-Jacob, Eshel; Volman, Vladislav; Hanein, Yael

    2008-01-01

    Increasing evidence supports the idea that spontaneous brain activity may have an important functional role. Cultured neuronal networks provide a suitable model system to search for the mechanisms by which neuronal spontaneous activity is maintained and regulated. This activity is marked by synchronized bursting events (SBEs)—short time windows (hundreds of milliseconds) of rapid neuronal firing separated by long quiescent periods (seconds). However, there exists a special subset of rapidly firing neurons whose activity also persists between SBEs. It has been proposed that these highly active (HA) neurons play an important role in the management (i.e. establishment, maintenance and regulation) of the synchronized network activity. Here, we studied the dynamical properties and the functional role of HA neurons in homogeneous and engineered networks, during early network development, upon recovery from chemical inhibition and in response to electrical stimulations. We found that their sequences of inter-spike intervals (ISI) exhibit long time correlations and a unimodal distribution. During the network's development and under intense inhibition, the observed activity follows a transition period during which mostly HA neurons are active. Studying networks with engineered geometry, we found that HA neurons are precursors (the first to fire) of the spontaneous SBEs and are more responsive to electrical stimulations

  18. Design professional activity analysis in design management

    Directory of Open Access Journals (Sweden)

    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.

  19. On applications of excess level processes to (N,D-policy bulk queueing systems

    Directory of Open Access Journals (Sweden)

    Jewgeni H. Dshalalow

    1996-01-01

    Full Text Available The paper deals with queueing systems in which N- and D-policies are combined into one. This means that an idle or vacationing server will resume his service if the queueing or workload process crosses some specified fixed level N or D, respectively. For the proposed (N,D-policy we study the queueing processes in models with and without server vacations, with compound Poisson input, and with generally distributed service and vacation periods. The analysis of the models is essentially based on fluctuation techniques for two-dimensional marked counting processes newly developed by the author. The results enable us to arrive at stationary distributions for the embedded and continuous time parameter queueing processes in closed analytic forms, enhancing the well-known Kendall formulas and their modifications.

  20. Fast distributed strategic learning for global optima in queueing access games

    KAUST Repository

    Tembine, Hamidou

    2014-01-01

    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

  1. Technical report on prototype intelligent network flow optimization (INFLO) dynamic speed harmonization and queue warning.

    Science.gov (United States)

    2015-06-01

    This Technical Report on Prototype Intelligent Network Flow Optimization (INFLO) Dynamic Speed Harmonization and : Queue Warning is the final report for the project. It describes the prototyping, acceptance testing and small-scale : demonstration of ...

  2. Mean time for the development of large workloads and large queue lengths in the GI/G/1 queue

    Directory of Open Access Journals (Sweden)

    Charles Knessl

    1996-01-01

    Full Text Available We consider the GI/G/1 queue described by either the workload U(t (unfinished work or the number of customers N(t in the system. We compute the mean time until U(t reaches excess of the level K, and also the mean time until N(t reaches N0. For the M/G/1 and GI/M/1 models, we obtain exact contour integral representations for these mean first passage times. We then compute the mean times asymptotically, as K and N0→∞, by evaluating these contour integrals. For the general GI/G/1 model, we obtain asymptotic results by a singular perturbation analysis of the appropriate backward Kolmogorov equation(s. Numerical comparisons show that the asymptotic formulas are very accurate even for moderate values of K and N0.

  3. Fluid queues driven by a birth and death process with alternating flow rates

    OpenAIRE

    P. R. Parthasarathy; K. V. Vijayashree; R. B. Lenin

    2004-01-01

    Fluid queue driven by a birth and death process (BDP) with only one negative effective input rate has been considered in the literature. As an alternative, here we consider a fluid queue in which the input is characterized by a BDP with alternating positive and negative flow rates on a finite state space. Also, the BDP has two alternating arrival rates and two alternating service rates. Explicit expression for the distribution function of the buffer occupancy is obtained. The case where the s...

  4. REGIONALIZATION OF MANAGEMENT PROCESS BY INNOVATIVE ACTIVITY

    Directory of Open Access Journals (Sweden)

    E. V. Sibirskaia

    2014-01-01

    Full Text Available Summary. In current market conditions, the economy and Russia's accession to international trade scholars and experts from various fields of knowledge paying special attention to a huge set of regional problems. The growing role of regional research determines the level of establishing effective mechanisms for the implementation of the economic interests of actors as well as economic development and improving the quality of human life is the priority objectives of federal, regional and local authorities. Today, the Russian economic science faces a global goal - to develop ways and means of transformation of the Russian economy and bring it to a path of sustainable, innovative development, providing new quality of life. Achieving this goal must surely be a central task of the Russian economics and politics, as in the near future and the long term In article authors opened the maintenance of determinants of innovative development of the territory, mediated by strengthening of regionalization of management by innovative activity: condition of resource and innovative potential; the developed forms and nature of interaction between public authorities of regional level, local community and business; applied forms of integration of subjects of managing for realization of their innovative potential due to expansion of opportunities of participation in the perspective directions of scientific and technical, economic and social development; system of the incentives developing favorable conditions for introduction and development of innovative technologies, and also increases in the enterprise activity, formed by the external institutional environment; regional economic policy as instrument of increase of efficiency of innovative activity.

  5. Performance Analysis and Optimal Allocation of Layered Defense M/M/N Queueing Systems

    Directory of Open Access Journals (Sweden)

    Longyue Li

    2016-01-01

    Full Text Available One important mission of strategic defense is to develop an integrated layered Ballistic Missile Defense System (BMDS. Motivated by the queueing theory, we presented a work for the representation, modeling, performance simulation, and channels optimal allocation of the layered BMDS M/M/N queueing systems. Firstly, in order to simulate the process of defense and to study the Defense Effectiveness (DE, we modeled and simulated the M/M/N queueing system of layered BMDS. Specifically, we proposed the M/M/N/N and M/M/N/C queueing model for short defense depth and long defense depth, respectively; single target channel and multiple target channels were distinguished in each model. Secondly, we considered the problem of assigning limited target channels to incoming targets, we illustrated how to allocate channels for achieving the best DE, and we also proposed a novel and robust search algorithm for obtaining the minimum channel requirements across a set of neighborhoods. Simultaneously, we presented examples of optimal allocation problems under different constraints. Thirdly, several simulation examples verified the effectiveness of the proposed queueing models. This work may help to understand the rules of queueing process and to provide optimal configuration suggestions for defense decision-making.

  6. Active traffic management case study: phase 1 : final report.

    Science.gov (United States)

    2016-03-01

    This study developed a systematic approach for using data from multiple sources to provide active traffic management : solutions. The feasibility of two active traffic management solutions is analyzed in this report: ramp-metering and real-time : cra...

  7. On the Discrete-Time GeoX/G/1 Queues under N-Policy with Single and Multiple Vacations

    Directory of Open Access Journals (Sweden)

    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.

  8. A bulk queueing system under N-policy with bilevel service delay discipline and start-up time

    Directory of Open Access Journals (Sweden)

    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.

  9. Radioactive Waste Management Program Activities in Croatia

    International Nuclear Information System (INIS)

    Matanic, R.

    2000-01-01

    The concept of radioactive waste management in Croatia comprises three major areas: management of low and intermediate level radioactive waste (LILRW), spent fuel management and decommissioning. All the work regarding radioactive waste management program is coordinated by Hazardous Waste Management Agency (APO) and Croatian Power Utility (HEP) in cooperation with other relevant institutions. Since the majority of work has been done in developing low and intermediate level radioactive waste management program, the paper will focus on this part of radioactive waste management, mainly on issues of site selection and characterization, repository design, safety assessment and public acceptance. A short description of national radioactive waste management infrastructure will also be presented. (author)

  10. Queueing in a spent fuel transportation system - preliminary analysis of implications for system design

    International Nuclear Information System (INIS)

    Cashwell, J.W.; Wood, T.W.

    1985-01-01

    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

  11. The Effectiveness Analysis of Waiting Processes in the Different Branches of a Bank by Queue Model

    Directory of Open Access Journals (Sweden)

    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.

  12. Queueing in a spent fuel transportation system: a preliminary analysis of implications for system design

    International Nuclear Information System (INIS)

    Cashwell, J.W.; Wood, T.W.

    1985-03-01

    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

  13. A queueing theory based model for business continuity in hospitals.

    Science.gov (United States)

    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.

  14. Priority Queues with Fractional Service for Tiered Delay QoS

    Directory of Open Access Journals (Sweden)

    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.

  15. BioQueue: a novel pipeline framework to accelerate bioinformatics analysis.

    Science.gov (United States)

    Yao, Li; Wang, Heming; Song, Yuanyuan; Sui, Guangchao

    2017-10-15

    With the rapid development of Next-Generation Sequencing, a large amount of data is now available for bioinformatics research. Meanwhile, the presence of many pipeline frameworks makes it possible to analyse these data. However, these tools concentrate mainly on their syntax and design paradigms, and dispatch jobs based on users' experience about the resources needed by the execution of a certain step in a protocol. As a result, it is difficult for these tools to maximize the potential of computing resources, and avoid errors caused by overload, such as memory overflow. Here, we have developed BioQueue, a web-based framework that contains a checkpoint before each step to automatically estimate the system resources (CPU, memory and disk) needed by the step and then dispatch jobs accordingly. BioQueue possesses a shell command-like syntax instead of implementing a new script language, which means most biologists without computer programming background can access the efficient queue system with ease. BioQueue is freely available at https://github.com/liyao001/BioQueue. The extensive documentation can be found at http://bioqueue.readthedocs.io. li_yao@outlook.com or gcsui@nefu.edu.cn. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  16. Approximate anlysis of an unreliable $M/M/c$ retrial queue with phase merging algorithm.

    Directory of Open Access Journals (Sweden)

    faiza BELARBI

    2016-06-01

    Full Text Available In this paper, we investigate an approximate analysis of unreliable $M/M/c$ retrial queue with $c\\geq 3$ in which all servers are subject to breakdowns and repairs. Arriving customers that are unable to access a server due to congestion or failure can choose to enter a retrial orbit for an exponentially distributed amount of time and persistently attempt to gain access to a server, or abandon their request and depart the system. Once a customer is admitted to a service station, they remain there for a random duration until service is complete and then depart the system. However, if the server fails during service, i.e., an active breakdown, the customer may choose to abandon the system or proceed directly to the retrial orbit while the server begins repair immediately. In the unreliable model, there are no exact solutions when the number of servers exceeds one. Therefore, we seek to approximate the steady-state joint distribution of the number of customers in orbit and the status of the $c$ servers for the case of Markovian arrival and service times. Our approach to deriving the approximate steady-state probabilities employs a phase-merging algorithm.

  17. Managing Siting Activities for Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-06-15

    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

  18. Managing Siting Activities for Nuclear Power Plants

    International Nuclear Information System (INIS)

    2012-01-01

    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

  19. NPS and the methadone queue: Spillages of space and time.

    Science.gov (United States)

    Alexandrescu, Liviu

    2017-02-01

    Between 2008 and 2013, powder-stimulants sold by 'head shops' as novel psychoactive substances (NPS) or 'legal highs' have displaced heroin among groups of injecting substance users in Bucharest, Romania. Rising HIV-infection rates and other medical or social harms have been reported to follow this trend. The study builds on two sets of original (N=30) and existing (N=20) interview data and on observations collected mainly at the site of a methadone substitution treatment facility. By disentangling the space-time continuum of the methadone queue, this paper argues that injecting drug users' (IDUs) passage from opiates to amphetamine-type stimulants (ATS) can be understood as 'spillages' of space and time. IDUs thus 'spill' out of the disciplinary flows of methadone treatment in two ways. The first is that of space and materiality. Drawing on actor-network theory (ANT), ATS/NPS appear embedded in reconfigured practices and rituals of injecting use. Such spillages see the pleasure-seeking self being fluidised in forming connections with, or spilling into, nonhuman actants such as substances, settings or objects. The second dimension of spilling is that of time. In this sense, heroin use is a 'cryogenic strategy' of inhabiting history and facing the transition to the market society that Romanian opiate injectors spill out of, not able to appropriate choice and legitimate consumption. The phenomenological qualities of stimulants that seem to accelerate lived time and generalise desire thus present them with an opportunity to alleviate a form of what a post-communist moral imaginary of transition frames as debilitating nostalgia. ATS/NPS are revealed as fluid entities that do not only shape risk conditions but also alter shared meanings and contextual configurations of bodies, substances and disciplinary regimes in unpredictable ways. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Approximations for the waiting-time distribution in an M/P H/c priority queue

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Alvarez, Elisa; van der Heijden, Matthijs C.

    2015-01-01

    We investigate the use of priority mechanisms when assigning service engineers to customers as a tool for service differentiation. To this end, we analyze a non-preemptive M/PH/c priority queue with various customer classes. For this queue, we present various accurate and fast methods to estimate

  1. Scaling and comparison of fluid limits of queues applied to call centers with time-varying parameters

    NARCIS (Netherlands)

    Jiménez, T.; Koole, G.M.

    2004-01-01

    Temporary overload situations in queues can be approximated by fluid queues. We strengthen earlier results on the comparison of multi-server tandem systems with their fluid limits. At the same time we give conditions under which economies of scale hold. We apply the results to call centers. ©

  2. On a first passage problem in general queueing systems with multiple vacations

    Directory of Open Access Journals (Sweden)

    Jewgeni H. Dshalalow

    1992-01-01

    Full Text Available The author studies a generalized single-server queueing system with bulk arrivals and batch service, where 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 modulated by the system and the service is assumed to be state dependent. One of the essential part in the analysis of the system is the employment of new techniques related to the first excess level processes. A preliminary analysis of such processes and recent results of the author on modulated processes enabled the author to obtain all major characteristics for the queueing process explicitly. Various examples and applications are discussed.

  3. On the optimal use of a slow server in two-stage queueing systems

    Science.gov (United States)

    Papachristos, Ioannis; Pandelis, Dimitrios G.

    2017-07-01

    We consider two-stage tandem queueing systems with a dedicated server in each queue and a slower flexible server that can attend both queues. We assume Poisson arrivals and exponential service times, and linear holding costs for jobs present in the system. We study the optimal dynamic assignment of servers to jobs assuming that two servers cannot collaborate to work on the same job and preemptions are not allowed. We formulate the problem as a Markov decision process and derive properties of the optimal allocation for the dedicated (fast) servers. Specifically, we show that the one downstream should not idle, and the same is true for the one upstream when holding costs are larger there. The optimal allocation of the slow server is investigated through extensive numerical experiments that lead to conjectures on the structure of the optimal policy.

  4. MX/G/1 unreliable retrial queue with option of additional service and Bernoulli vacation

    Directory of Open Access Journals (Sweden)

    Charan Jeet Singh

    2016-03-01

    Full Text Available In this paper, retrial queue with unreliable server and bulk arrivals is investigated. The server is capable of providing m-optional services and any one of these available services, may be rendered to the customer after the first essential service if the customer opts for the same. It is assumed that the server may fail while rendering any phase of service and undergoes for the immediate repair. After the completion of the service of a customer, the server may either take a vacation for a random period or may continue to provide the service to the other customers waiting in the queue. The supplementary variables corresponding to service time, repair time and retrial time are incorporated to determine the queue size distribution. To examine the effect of different parameters on the performance measures of the system, the numerical illustration is given which is supported by numerical simulation and sensitivity analysis.

  5. Some reflections on the Renewal-theory paradox in queueing theory

    Directory of Open Access Journals (Sweden)

    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.

  6. Maintenance in Single-Server Queues: A Game-Theoretic Approach

    Directory of Open Access Journals (Sweden)

    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.

  7. A discrete single server queue with Markovian arrivals and phase type group services

    Directory of Open Access Journals (Sweden)

    Attahiru Sule Alfa

    1995-01-01

    Full Text Available We consider a single-server discrete queueing system in which arrivals occur according to a Markovian arrival process. Service is provided in groups of size no more than M customers. The service times are assumed to follow a discrete phase type distribution, whose representation may depend on the group size. Under a probabilistic service rule, which depends on the number of customers waiting in the queue, this system is studied as a Markov process. This type of queueing system is encountered in the operations of an automatic storage retrieval system. The steady-state probability vector is shown to be of (modified matrix-geometric type. Efficient algorithmic procedures for the computation of the rate matrix, steady-state probability vector, and some important system performance measures are developed. The steady-state waiting time distribution is derived explicitly. Some numerical examples are presented.

  8. ANALYSIS OF FUZZY QUEUES: PARAMETRIC PROGRAMMING APPROACH BASED ON RANDOMNESS - FUZZINESS CONSISTENCY PRINCIPLE

    Directory of Open Access Journals (Sweden)

    Dhruba Das

    2015-04-01

    Full Text Available In this article, based on Zadeh’s extension principle we have apply the parametric programming approach to construct the membership functions of the performance measures when the interarrival time and the service time are fuzzy numbers based on the Baruah’s Randomness- Fuzziness Consistency Principle. The Randomness-Fuzziness Consistency Principle leads to defining a normal law of fuzziness using two different laws of randomness. In this article, two fuzzy queues FM/M/1 and M/FM/1 has been studied and constructed their membership functions of the system characteristics based on the aforesaid principle. The former represents a queue with fuzzy exponential arrivals and exponential service rate while the latter represents a queue with exponential arrival rate and fuzzy exponential service rate.

  9. Optimal Service Capacities in a Competitive Multiple-Server Queueing Environment

    Science.gov (United States)

    Ching, Wai-Ki; Choi, Sin-Man; Huang, Min

    The study of economic behavior of service providers in a competition environment is an important and interesting research issue. A two-server queueing model has been proposed in Kalai et al. [11] for this purpose. Their model aims at studying the role and impact of service capacity in capturing larger market share so as to maximize the long-run expected profit. They formulate the problem as a two-person strategic game and analyze the equilibrium solutions. The main aim of this paper is to extend the results of the two-server queueing model in [11] to the case of multiple servers. We will only focus on the case when the queueing system is stable.

  10. Timing of nurses activities: human resources management

    Directory of Open Access Journals (Sweden)

    Hamid Hosein Poor

    2016-11-01

    Full Text Available Costs of human resources include a high percentage of hospital’s costs; therefore, determination of number of real and optimal employees needed for organizations is very important. In the meantime, the optimal organization of nurses, as the biggest human resource in health care organizations, is of great importance. The present study aimed to assess the distribution of nurses’ activities in shifts and the results of productivity in human resources management in Imam Khomeini hospital in Shirvan. The present cross-sectional study was conducted in 2016. All nurses, working in three shifts of morning, afternoon, and evening in emergency unit and general units of Imam Khomeini hospital, Shirvan, were enrolled into the study through census methods. The instrument, used in this study, was the checklist of timing activities and patients’ satisfaction from nurses. The statistical software SPSS was used for analysis. Mean age of employees in these two units/wards was 31 years and mean duration of work experience was 5.24 years, The difference was significant between the two wards. necessity of the work, especially in emergency unit, are issues that need more assessment and need to be adjusted. Given the high volume of non-care matters of nursing staff, including writing services, including completing paper records and work with HIS (Hospital Information System, which has been emphasized in several studies, new definition of service and use of artificial intelligence with high efficacy is proposed. The status of the available equipment, availability, and efficiency of digital equipment and hoteling state of wards and hospitals also play an important factor in the distribution of time of nursing care activities. Employment of nurses to perform non-nursing duties, because of the shortage of other classes or lack of their permanent presence and based on Although there were differences in standard time of direct and indirect care in emergency unit and

  11. General bulk service queueing system with N-policy, multiplevacations, setup time and server breakdown without interruption

    Science.gov (United States)

    Sasikala, S.; Indhira, K.; Chandrasekaran, V. M.

    2017-11-01

    In this paper, we have considered an MX / (a,b) / 1 queueing system with server breakdown without interruption, multiple vacations, setup times and N-policy. After a batch of service, if the size of the queue is ξ (customers in the queue. After a vacation, if the server finds at least N customers waiting for service, then the server needs a setup time to start the service. After a batch of service, if the amount of waiting customers in the queue is ξ (≥ a) then the server serves a batch of min(ξ,b) customers, where b ≥ a. We derived the probability generating function of queue length at arbitrary time epoch. Further, we obtained some important performance measures.

  12. A finite-buffer queue with a single vacation policy: An analytical study with evolutionary positioning

    Directory of Open Access Journals (Sweden)

    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.

  13. An M/M/2 Queueing System with Heterogeneous Servers Including One with Working Vacation

    Directory of Open Access Journals (Sweden)

    A. Krishnamoorthy

    2012-01-01

    Full Text Available This paper analyzes an M/M/2 queueing system with two heterogeneous servers, one of which is always available but the other goes on vacation in the absence of customers waiting for service. The vacationing server, however, returns to serve at a low rate as an arrival finds the other server busy. The system is analyzed in the steady state using matrix geometric method. Busy period of the system is analyzed and mean waiting time in the stationary regime computed. Conditional stochastic decomposition of stationary queue length is obtained. An illustrative example is also provided.

  14. An MX/GI/1/N queue with close-down and vacation times

    Directory of Open Access Journals (Sweden)

    Andreas Frey

    1999-01-01

    Full Text Available An MX/GI/1/N finite capacity queue with close-down time, vacation time and exhaustive service discipline is considered under the partial batch acceptance strategy as well as under the whole batch acceptance strategy. Applying the supplementary variable technique the queue length distribution at an arbitrary instant and at a departure epoch is obtained under both strategies, where no assumption on the batch size distribution is made. The loss probabilities and the Laplace-Stieltjes transforms of the waiting time distribution of the first customer and of an arbitrary customer of a batch are also given. Numerical examples give some insight into the behavior of the system.

  15. A Novel Analytic Technique for the Service Station Reliability in a Discrete-Time Repairable Queue

    Directory of Open Access Journals (Sweden)

    Renbin Liu

    2013-01-01

    Full Text Available This paper presents a decomposition technique for the service station reliability in a discrete-time repairable GeomX/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 numerical examples validate the derived results and show that our analytic technique is applicable to reliability analysis of some complex discrete-time repairable bulk arrival queueing systems.

  16. The Geo/Geo/1+1 Queueing System with Negative Customers

    OpenAIRE

    Ma, Zhanyou; Guo, Yalin; Wang, Pengcheng; Hou, Yumei

    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, ...

  17. The Jackson Queueing Network Model Built Using Poisson Measures. Application To A Bank Model

    Directory of Open Access Journals (Sweden)

    Ciuiu Daniel

    2014-07-01

    Full Text Available In this paper we will build a bank model using Poisson measures and Jackson queueing networks. We take into account the relationship between the Poisson and the exponential distributions, and we consider for each credit/deposit type a node where shocks are modeled as the compound Poisson processes. The transmissions of the shocks are modeled as moving between nodes in Jackson queueing networks, the external shocks are modeled as external arrivals, and the absorption of shocks as departures from the network.

  18. A queueing model for error control of partial buffer sharing in ATM

    Directory of Open Access Journals (Sweden)

    Ahn Boo Yong

    1999-01-01

    Full Text Available We model the error control of the partial buffer sharing of ATM by a queueing system M 1 , M 2 / G / 1 / K + 1 with threshold and instantaneous Bernoulli feedback. We first derive the system equations and develop a recursive method to compute the loss probabilities at an arbitrary time epoch. We then build an approximation scheme to compute the mean waiting time of each class of cells. An algorithm is developed for finding the optimal threshold and queue capacity for a given quality of service.

  19. The Application of The Double Queue Asymmetric Gated Service Polling Control Theory in Intelligent Traffic System

    Directory of Open Access Journals (Sweden)

    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.

  20. The M/M/1 queue with inventory, lost sale and general lead times

    DEFF Research Database (Denmark)

    Saffari, Mohammad; Asmussen, Søren; Haji, Rasoul

    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...... 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....

  1. Chaotic queue-based genetic algorithm for design of a self-tuning fuzzy logic controller

    Science.gov (United States)

    Saini, Sanju; Saini, J. S.

    2012-11-01

    This paper employs a chaotic queue-based method using logistic equation in a non-canonical genetic algorithm for optimizing the performance of a self-tuning Fuzzy Logic Controller, used for controlling a nonlinear double-coupled system. A comparison has been made with a standard canonical genetic algorithm implemented on the same plant. It has been shown that chaotic queue-method brings an improvement in the performance of the FLC for wide range of set point changes by a more profound initial population spread in the search space.

  2. The Management System for Facilities and Activities. Safety Requirements

    International Nuclear Information System (INIS)

    2011-01-01

    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.

  3. Development of a Traffic Management Decision Support Tool for Freeway Incident Traffic Management (FITM) Plan Deployment : Research Summary

    Science.gov (United States)

    2017-12-01

    In designing an effective traffic management plan for non-recurrent congestion, it is critical for responsible highway agencies to have some vital information, such as estimated incident duration, resulting traffic queues, and the expected delays. Ov...

  4. US - Former Soviet Union environmental management activities

    International Nuclear Information System (INIS)

    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

  5. ITS data management system : year one activities

    Science.gov (United States)

    1997-08-01

    This report documents research conducted in the development of an ITS data management system, hereafter referred to as ITS DataLink. The objective of the ITS DataLink system is to retain, manage, share, and analyze ITS data for a variety of tra...

  6. A Study on improvement of comprehensive environmental management system - activation of liberalized environmental management

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Hweu Sung; Kang, Chul Goo [Korea Environment Institute, Seoul (Korea)

    1998-12-01

    As a part of improvement on a comprehensive environmental management system, this study was attempted to find an activating policy for a liberalized environmental management. This study provided an activation plan of reasonable environmental regulation reform and liberalized environmental management through the analysis of foreign examples and domestic situation. Furthermore, it analyzed an institutional mechanism for a smooth operation of liberalized environmental management. 68 refs., 5 figs., 51 tabs.

  7. Fast concurrent array-based stacks, queues and deques using fetch-and-increment-bounded, fetch-and-decrement-bounded and store-on-twin synchronization primitives

    Science.gov (United States)

    Chen, Dong; Gara, Alana; Heidelberger, Philip; Kumar, Sameer; Ohmacht, Martin; Steinmacher-Burow, Burkhard; Wisniewski, Robert

    2014-09-16

    Implementation primitives for concurrent array-based stacks, queues, double-ended queues (deques) and wrapped deques are provided. In one aspect, each element of the stack, queue, deque or wrapped deque data structure has its own ticket lock, allowing multiple threads to concurrently use multiple elements of the data structure and thus achieving high performance. In another aspect, new synchronization primitives FetchAndIncrementBounded (Counter, Bound) and FetchAndDecrementBounded (Counter, Bound) are implemented. These primitives can be implemented in hardware and thus promise a very fast throughput for queues, stacks and double-ended queues.

  8. Nuclear power company activity based costing management analysis

    International Nuclear Information System (INIS)

    Xu Dan

    2012-01-01

    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)

  9. Importance of marketing activities in a company : the management perspective

    OpenAIRE

    Urbonavičius, Sigitas; Dikčius, Vytautas

    2008-01-01

    The article analyses how managers of companies see the importance of the overall marketing function as the importance of certain types of marketing activities. These types include typical areas of 4 Ps as well as marketing planning and marketing research activities. The research is based on a survey of 205 managers of primarily manufacturing and trading companies that operate in Lithuania. Managers evaluated marketing planning and distribution as the most important marketing functions, while ...

  10. US - Former Soviet Union environmental management activities

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. On the Control of a Queueing System with Aging State Information

    NARCIS (Netherlands)

    M. Onderwater (Martijn); S. Bhulai (Sandjai); R.D. van der Mei (Rob)

    2015-01-01

    htmlabstractWe investigate control of a queueing system in which a component of the state space is subject to aging. The controller can choose to forward incoming queries to the system (where it needs time for processing), or respond with a previously generated response (incurring a penalty for not

  12. Queue-based modelling and detection of parameters involved in stroke outcome

    DEFF Research Database (Denmark)

    Vilic, Adnan; Petersen, John Asger; Wienecke, Troels

    2017-01-01

    We designed a queue-based model, and investigated which parameters are of importance when predicting stroke outcome. Medical record forms have been collected for 57 ischemic stroke patients, including medical history and vital sign measurement along with neurological scores for the first twenty...

  13. Sojourn times in the M/G/1 FB queue with light-tailed service times

    NARCIS (Netherlands)

    M.R.H. Mandjes (Michel); M. Nuyens

    2004-01-01

    textabstractThe asymptotic decay rate of the sojourn time of a customer in the stationary M/G/1 queue under the Foreground-Background (FB) service discipline is studied. The FB discipline gives service to those customers that have received the least service so far. We prove that for light-tailed

  14. The priority queue as an example of hardware/software codesign

    DEFF Research Database (Denmark)

    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...

  15. Transient analysis of an M/M/1 queue with multiple vacations

    Directory of Open Access Journals (Sweden)

    Kaliappan Kalidass

    2014-05-01

    Full Text Available In this paper, we have obtained explicit expressions for the time dependent probabilities of the M/M/1  queue with server vacations under a multiple vacation scheme. The corresponding steady state probabilities have been obtained. We also obtain the time dependent performance measures of the systems

  16. On the correlation structure of a Lévy-driven queue

    NARCIS (Netherlands)

    A. Es-Saghouani; M.R.H. Mandjes (Michel)

    2007-01-01

    textabstractIn this paper we consider a single-server queue with Lévy input, and in particular its workload process (Q(t)), for t > 0, with a focus on the correlation structure. With the correlation function defined as r(t) := Cov(Q(0),Q(t))/Var Q(0) (assuming that the workload process is in

  17. The Remaining Service Time Upon Reaching a High Level in M/G/1 Queues

    NARCIS (Netherlands)

    de Boer, Pieter-Tjerk; Nicola, V.F.; van Ommeren, Jan C.W.

    The distribution of the remaining service time upon reaching some target level in an M/G/1 queue is of theoretical as well as practical interest. In general, this distribution depends on the initial level as well as on the target level, say, B. Two initial levels are of particular interest, namely,

  18. Response times in a two-node queueing network with feedback

    NARCIS (Netherlands)

    van der Mei, R.D.; Gijsen, B.M.M.; in 't Veld, N.; van den Berg, J.L.

    2002-01-01

    The study presented in this paper is motivated by the performance analysis of response times in distributed information systems, where transactions are handled by iterative server and database actions. We model system response times as sojourn times in a two-node open queueing network with a

  19. Response times in a two-node queueing network with feedback

    NARCIS (Netherlands)

    van der Mei, R.D.; Gijsen, B.M.M.; Gijsen, B.M.M.; in 't Veld, N.; van den Berg, Hans Leo

    The study presented in this paper is motivated by the performance analysis of response times in distributed information systems, where transactions are handled by iterative server and database actions. We model system response times as sojourn times in a two-node open queueing network with a

  20. A Busy period analysis of the level dependent PH/PH/1/K queue

    NARCIS (Netherlands)

    Al Hanbali, Ahmad

    2011-01-01

    In this paper, we study the transient behavior of a level dependent single server queuing system with a waiting room of finite size during the busy period. The focus is on the level dependent PH/PH/1/K queue. We derive in closed form the joint transform of the length of the busy period, the number

  1. A Busy period analysis for the state dependent M/M/1/K queue

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Boxma, Onno

    2010-01-01

    In this paper, we study the transient behavior of a state dependent M/M/1/K queue during the busy period. We derive in closed-form the joint transform of the length of the busy period, the number of customers served during the busy period, and the number of losses during the busy period. For two

  2. Sojourn time asymptotics in Processor Sharing queues with varying service rate

    NARCIS (Netherlands)

    Egorova, R.; Mandjes, M.R.H.; Zwart, B.

    2007-01-01

    Abstract This paper addresses the sojourn time asymptotics for a GI/GI/⋅ queue operating under the Processor Sharing (PS) discipline with stochastically varying service rate. Our focus is on the logarithmic estimates of the tail of sojourn-time distribution, under the assumption that the job-size

  3. Proposition of delay model for signalized intersections with queueing theory analytical models usage

    Directory of Open Access Journals (Sweden)

    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.

  4. The M/G/1 queue with quasi-restricted accessibility

    NARCIS (Netherlands)

    Boxma, O.J.; Perry, D.; Stadje, W.; Zacks, S.

    2009-01-01

    We consider single-server queues of the M/G/1 kind with a special kind of partial customer rejection called quasi-restricted accessibility (QRA). Under QRA, the actual service time assigned to an arriving customer depends on his service requirement, say x, the current workload, say w, and a

  5. Simple product-form bounds for queueing networks with finite clusters

    NARCIS (Netherlands)

    van Dijk, N.M.; van der Sluis, E.

    2001-01-01

    Queueing networks are studied with finite capacity constraints for clusters of stations. First, by an instructive tandem cluster example it is shown how a product-form modification method for networks with finite stations can be extended to networks with finite clusters. Next, a general result is

  6. Simulation-based computation of the workload correlation function in a Lévy-driven queue

    NARCIS (Netherlands)

    Glynn, P.W.; Mandjes, M.

    2011-01-01

    In this paper we consider a single-server queue with Lévy input, and, in particular, its workload process (Qt)t≥0, focusing on its correlation structure. With the correlation function defined as r(t):= cov(Q0, Qt) / varQ0 (assuming that the workload process is in stationarity at time 0), we first

  7. Simulation-based computation of the workload correlation function in a Levy-driven queue

    NARCIS (Netherlands)

    P. Glynn; M.R.H. Mandjes (Michel)

    2009-01-01

    htmlabstractIn this paper we consider a single-server queue with Levy input, and in particular its workload process (Q_t), focusing on its correlation structure. With the correlation function defined as r(t) := Cov(Q_0, Q_t)/Var Q_0 (assuming the workload process is in stationarity at time 0), we

  8. Simulation-based computation of the workload correlation function in a Lévy-driven queue

    NARCIS (Netherlands)

    P. Glynn; M.R.H. Mandjes (Michel)

    2010-01-01

    htmlabstractIn this paper we consider a single-server queue with Levy input, and in particular its workload process (Q_t), focusing on its correlation structure. With the correlation function defined as r(t) := Cov(Q_0,Q_t)/Var(Q_0) (assuming the workload process is in stationarity at time 0), we

  9. Waiting as Part of the Fun: Interactive Gaming in Theme Park Queues

    NARCIS (Netherlands)

    Heger, Chris; Offermans, S.A.M.; Frens, J.W.; Wouters, I.H.C.; Kimman, F.P.F.; Tieben, R.; Offermans, S.A.M.; Nagtzaam, H.A.H.

    2009-01-01

    People visiting theme parks intend to have a day of fun. Yet a larger part of the time is spent queuing for rides rather than in the actual rides, which does not contribute to the intended fun experience. Current efforts therefore either make the queue as bearable as possible or try to get rid of it

  10. A computational approach for fluid queues driven by truncated birth-death processes.

    NARCIS (Netherlands)

    Lenin, R.B.; Parthasarathy, P.R.

    2000-01-01

    In this paper, we analyze fluid queues driven by truncated birth-death processes with general birth and death rates. We compute the equilibrium distribution of the content of the fluid buffer by providing efficient numerical procedures to compute the eigenvalues and the eigenvectors of the

  11. Self-organization of critical behavior in controlled general queueing models

    International Nuclear Information System (INIS)

    Blanchard, Ph.; Hongler, M.-O.

    2004-01-01

    We consider general queueing models of the (G/G/1) type with service times controlled by the busy period. For feedback control mechanisms driving the system to very high traffic load, it is shown the busy period probability density exhibits a generic -((3)/(2)) power law which is a typical mean field behavior of SOC models

  12. A two-station queue with dependent preparation and service times

    NARCIS (Netherlands)

    Vlasiou, M.; Adan, I.J.B.F.; Boxma, O.J.

    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

  13. On first-come first-served versus random service discipline in multiclass closed queueing networks

    NARCIS (Netherlands)

    Buitenhek, R.; van Houtum, Geert-Jan; van Ommeren, Jan C.W.

    1997-01-01

    We consider multiclass closed queueing networks. For these networks, a lot of work has been devoted to characterizing and weakening the conditions under which a product-form solution is obtained for the steady-state distribution. From this work, it is known that, under certain conditions, all

  14. Fokker-Planck description for the queue dynamics of large tick stocks

    Science.gov (United States)

    Garèche, A.; Disdier, G.; Kockelkoren, J.; Bouchaud, J.-P.

    2013-09-01

    Motivated by empirical data, we develop a statistical description of the queue dynamics for large tick assets based on a two-dimensional Fokker-Planck (diffusion) equation. Our description explicitly includes state dependence, i.e., the fact that the drift and diffusion depend on the volume present on both sides of the spread. “Jump” events, corresponding to sudden changes of the best limit price, must also be included as birth-death terms in the Fokker-Planck equation. All quantities involved in the equation can be calibrated using high-frequency data on the best quotes. One of our central findings is that the dynamical process is approximately scale invariant, i.e., the only relevant variable is the ratio of the current volume in the queue to its average value. While the latter shows intraday seasonalities and strong variability across stocks and time periods, the dynamics of the rescaled volumes is universal. In terms of rescaled volumes, we found that the drift has a complex two-dimensional structure, which is a sum of a gradient contribution and a rotational contribution, both stable across stocks and time. This drift term is entirely responsible for the dynamical correlations between the ask queue and the bid queue.

  15. A numerical solution for the multi-server queue with hyper-exponential service times

    NARCIS (Netherlands)

    de Smit, J.H.A.

    1983-01-01

    In this paper we present a numerical method for the queue GI/H2/s, which is based on general results for GI/Hm/s. We give a complete description of the algorithm which yields exact results for the steady distributions of the actual waiting time, the virtual waiting time and the number of customers

  16. Sojourn times in the M/G/1 FB queue with light-tailed service times.

    NARCIS (Netherlands)

    Mandjes, M.R.H.; Nuijens, M.F.M.

    2005-01-01

    ABSTRACT The asymptotic decay rate of the sojourn time of a customer in the stationary M/G/1 queue under the Foreground-Background (FB) service discipline is studied. The FB discipline gives service to those customers that have received the least service so far. We prove that for lighttailed service

  17. Optimal hysteretic control for a BMAP/SM/1/N queue with two operation modes

    Directory of Open Access Journals (Sweden)

    Alexander N. Dudin

    2000-01-01

    Full Text Available We consider BMAP/SM/1 type queueing system with finite buffer of size N. The system has two operation modes, which are characterized by the matrix generating function of BMAP-input, the kernel of the semi-Markovian service process, and utilization cost. An algorithm for determining the optimal hysteresis strategy is presented.

  18. Simple approximations for the batch-arrival MX/G/1 queue

    NARCIS (Netherlands)

    van Ommeren, Jan C.W.

    1990-01-01

    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

  19. Heavy-traffic analysis for the GI/G/1 queue with heavy-tailed distributions

    NARCIS (Netherlands)

    O.J. Boxma (Onno); J.W. Cohen

    1997-01-01

    textabstractWe consider a $GI/G/1$ queue in which the service time distribution and/or the interarrival time distribution has a heavy tail, i.e., a tail behaviour like $t^{-nu$ with $1

  20. The M/G/1 queue with heavy-tailed service time distribution

    NARCIS (Netherlands)

    Boxma, O.J.; Cohen, J.W.

    1998-01-01

    In modern teletraffic applications of queueing theory, service time distributions B(t) with a heavy tail occur, i.e., 1-B(t)~Ct-v for t¿8 with v>1. For such service time distributions, not much explicit information is available concerning the tail probabilities of the corresponding waiting time

  1. Sojourn time asymptotics in the M/G/1 processor sharing queue

    NARCIS (Netherlands)

    A.P. Zwart (Bert); O.J. Boxma (Onno)

    1998-01-01

    textabstractWe show for the M/G/1 processor sharing queue that the service time distribution is regularly varying of index $-nu$, $nu$ non-integer, iff the sojourn time distribution is regularly varying of index $-nu $. This result is derived from a new expression for the Laplace-Stieltjes transform

  2. Positive Harris recurrence and diffusion scale analysis of a push pull queueing network

    NARCIS (Netherlands)

    Nazarathy, J.; Weiss, G.

    2010-01-01

    We consider a push pull queueing network with two servers and two types of job which are processed by the two servers in opposite order, with stochastic generally distributed processing times. This push pull network was introduced by Kopzon and Weiss, who assumed exponential processing times. It is

  3. Transient analysis of one-sided Lévy-driven queues

    NARCIS (Netherlands)

    Starreveld, N.J.; Bekker, R.; Mandjes, M.

    2016-01-01

    In this article, we analyze the transient behavior of the workload process in a Lévy-driven queue. We are interested in the value of the workload process at a random epoch; this epoch is distributed as the sum of independent exponential random variables. We consider both cases of spectrally

  4. Transient analysis of one-sided Lévy-driven queues

    NARCIS (Netherlands)

    Starreveld, N.J.; R. Bekker (Rene); M.R.H. Mandjes (Michel)

    2016-01-01

    textabstractIn this article, we analyze the transient behavior of the workload process in a Lévy-driven queue. We are interested in the value of the workload process at a random epoch; this epoch is distributed as the sum of independent exponential random variables. We consider both cases of

  5. Transient analysis of one-sided Lévy-driven queues

    NARCIS (Netherlands)

    Starreveld, N.; Bekker, R.; Mandjes, M.R.H.

    2015-01-01

    In this paper we analyze the transient behavior of the workload process in a Lévy input queue. We are interested in the value of the workload process at a random epoch; this epoch is distributed as the sum of independent exponential random variables. We consider both cases of spectrally one-sided

  6. A computational approach for a fluid queue driven by a truncated birth-death process

    NARCIS (Netherlands)

    Lenin, R.B.; Parthasarathy, P.R.

    1999-01-01

    In this paper, we consider a fluid queue driven by a truncated birth-death process with general birth and death rates. We find the equilibrium distribution of the content of the fluid buffer by computing the eigenvalues and eigenvectors of an associated real tridiagonal matrix. We provide efficient

  7. Equilibrium arrival times to queues with general service times and non-linear utility functions

    DEFF Research Database (Denmark)

    Breinbjerg, Jesper

    2017-01-01

    by a general utility function which is decreasing in the waiting time and service completion time of each customer. Applications of such queueing games range from people choosing when to arrive at a grand opening sale to travellers choosing when to line up at the gate when boarding an airplane. We develop...

  8. Self-organization of critical behavior in controlled general queueing models

    Science.gov (United States)

    Blanchard, Ph.; Hongler, M.-O.

    2004-03-01

    We consider general queueing models of the (G/G/1) type with service times controlled by the busy period. For feedback control mechanisms driving the system to very high traffic load, it is shown the busy period probability density exhibits a generic - {3}/{2} power law which is a typical mean field behavior of SOC models.

  9. Optimal control for an M^X/G/1/N+1 queue with two service modes

    NARCIS (Netherlands)

    Ridder, A.A.N.; Nobel, R.D.; Krishnan, G.S.S.; Anita, R.; Lakshmi, R.S.; Kumar, M.S.; Bonato, A.; Grana, M.

    2014-01-01

    A finite-buffer queueing model is considered with batch Poisson input and controllable service rate. A batch that upon arrival does not fit in the unoccupied places of the buffer is partially rejected. A decision to change the service mode can be made at service completion epochs only, and vacation

  10. Production Task Queue Optimization Based on Multi-Attribute Evaluation for Complex Product Assembly Workshop.

    Science.gov (United States)

    Li, Lian-Hui; Mo, Rong

    2015-01-01

    The production task queue has a great significance for manufacturing resource allocation and scheduling decision. Man-made qualitative queue optimization method has a poor effect and makes the application difficult. A production task queue optimization method is proposed based on multi-attribute evaluation. According to the task attributes, the hierarchical multi-attribute model is established and the indicator quantization methods are given. To calculate the objective indicator weight, criteria importance through intercriteria correlation (CRITIC) is selected from three usual methods. To calculate the subjective indicator weight, BP neural network is used to determine the judge importance degree, and then the trapezoid fuzzy scale-rough AHP considering the judge importance degree is put forward. The balanced weight, which integrates the objective weight and the subjective weight, is calculated base on multi-weight contribution balance model. The technique for order preference by similarity to an ideal solution (TOPSIS) improved by replacing Euclidean distance with relative entropy distance is used to sequence the tasks and optimize the queue by the weighted indicator value. A case study is given to illustrate its correctness and feasibility.

  11. Production Task Queue Optimization Based on Multi-Attribute Evaluation for Complex Product Assembly Workshop.

    Directory of Open Access Journals (Sweden)

    Lian-Hui Li

    Full Text Available The production task queue has a great significance for manufacturing resource allocation and scheduling decision. Man-made qualitative queue optimization method has a poor effect and makes the application difficult. A production task queue optimization method is proposed based on multi-attribute evaluation. According to the task attributes, the hierarchical multi-attribute model is established and the indicator quantization methods are given. To calculate the objective indicator weight, criteria importance through intercriteria correlation (CRITIC is selected from three usual methods. To calculate the subjective indicator weight, BP neural network is used to determine the judge importance degree, and then the trapezoid fuzzy scale-rough AHP considering the judge importance degree is put forward. The balanced weight, which integrates the objective weight and the subjective weight, is calculated base on multi-weight contribution balance model. The technique for order preference by similarity to an ideal solution (TOPSIS improved by replacing Euclidean distance with relative entropy distance is used to sequence the tasks and optimize the queue by the weighted indicator value. A case study is given to illustrate its correctness and feasibility.

  12. Networks of ·/G/∞ queues with shot-noise-driven arrival intensities

    NARCIS (Netherlands)

    Koops, D.T.; Boxma, O.J.; Mandjes, M.R.H.

    2017-01-01

    We study infinite-server queues in which the arrival process is a Cox process (or doubly stochastic Poisson process), of which the arrival rate is given by a shot-noise process. A shot-noise rate emerges naturally in cases where the arrival rate tends to exhibit sudden increases (or shots) at random

  13. The CMS workload management system

    Energy Technology Data Exchange (ETDEWEB)

    Cinquilli, M. [CERN; Evans, D. [Fermilab; Foulkes, S. [Fermilab; Hufnagel, D. [Fermilab; Mascheroni, M. [CERN; Norman, M. [UC, San Diego; Maxa, Z. [Caltech; Melo, A. [Vanderbilt U.; Metson, S. [Bristol U.; Riahi, H. [INFN, Perugia; Ryu, S. [Fermilab; Spiga, D. [CERN; Vaandering, E. [Fermilab; Wakefield, Stuart [Imperial Coll., London; Wilkinson, R. [Caltech

    2012-01-01

    CMS has started the process of rolling out a new workload management system. This system is currently used for reprocessing and Monte Carlo production with tests under way using it for user analysis. It was decided to combine, as much as possible, the production/processing, analysis and T0 codebases so as to reduce duplicated functionality and make best use of limited developer and testing resources. This system now includes central request submission and management (Request Manager), a task queue for parcelling up and distributing work (WorkQueue) and agents which process requests by interfacing with disparate batch and storage resources (WMAgent).

  14. The CMS workload management system

    International Nuclear Information System (INIS)

    Cinquilli, M; Mascheroni, M; Spiga, D; Evans, D; Foulkes, S; Hufnagel, D; Ryu, S; Vaandering, E; Norman, M; Maxa, Z; Wilkinson, R; Melo, A; Metson, S; Riahi, H; Wakefield, S

    2012-01-01

    CMS has started the process of rolling out a new workload management system. This system is currently used for reprocessing and Monte Carlo production with tests under way using it for user analysis. It was decided to combine, as much as possible, the production/processing, analysis and T0 codebases so as to reduce duplicated functionality and make best use of limited developer and testing resources. This system now includes central request submission and management (Request Manager); a task queue for parcelling up and distributing work (WorkQueue) and agents which process requests by interfacing with disparate batch and storage resources (WMAgent).

  15. Experiences of Fast Queue health care users in primary health care facilities in eThekwini district, South AfricaExperiences of Fast Queue health care users in primary health care facilities in eThekwini district, South Africa

    Directory of Open Access Journals (Sweden)

    Dudu G. Sokhela

    2013-07-01

    Full Text Available Background: Comprehensive Primary Health Care (PHC, based on the principles of accessibility, availability, affordability, equity and acceptability, was introduced in South Africa to address inequalities in health service provision. Whilst the Fast Queue was instrumental in the promotion of access to health care, a major goal of the PHC approach, facilities were not prepared for the sudden influx of clients. Increased access resulted in long waiting times and queues contributing to dissatisfaction with the service which could lead to missed appointments and non-compliance with established treatment plans.Objectives: Firstly to describe the experiences of clients using the Fast Queue strategy to access routine healthcare services and secondly, to determine how the clients’ experiences led to satisfaction or dissatisfaction with the Fast Queue service.Method: A descriptive qualitative survey using content analysis explored the experiences of the Fast Queue users in a PHC setting. Setting was first identified based on greatest number using the Fast Queue and geographic diversity and then a convenience sample of health care users of the Fast Queue were sampled individually along with one focus group of users who accessed the Queue monthly for medication refills. The same interview guide questions were used for both individual interviews and the one focus group discussion. Five clinics with the highest number of attendees during a three month period and a total of 83 health care users of the Fast Queue were interviewed. The average participant was female, 31 years old, single and unemployed.Results: Two themes with sub-themes emerged: health care user flow and communication, which highlights both satisfaction and dissatisfaction with the fast queue and queue marshals, could assist in directing users to the respective queues, reduce waiting time and keep users satisfied with the use of sign posts where there is a lack of human resources

  16. ANDRA 2009 activity report: managing today to prepare the future

    International Nuclear Information System (INIS)

    2010-01-01

    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

  17. Task and Interruption Management in Activity-Centric Computing

    DEFF Research Database (Denmark)

    Jeuris, Steven

    to address these not in isolation, but by fundamentally reevaluating the current computing paradigm. To this end, activity-centric computing has been brought forward as an alternative computing paradigm, addressing the increasing strain put on modern-day computing systems. Activity-centric computing follows...... the scalability and intelligibility of current research prototypes. In this dissertation, I postulate that such issues arise due to a lack of support for the full set of practices which make up activity management. Most notably, although task and interruption management are an integral part of personal...... information management, they have thus far been neglected in prior activity-centric computing systems. Advancing the research agenda of activity-centric computing, I (1) implement and evaluate an activity-centric desktop computing system, incorporating support for interruptions and long-term task management...

  18. International Project Management Committee: Overview and Activities

    Science.gov (United States)

    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.

  19. Quarterly Briefing Book on Environmental and Waste Management Activities

    International Nuclear Information System (INIS)

    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

  20. Quarterly Briefing Book on Environmental and Waste Management Activities

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Decommissioning project management unit started its activities

    International Nuclear Information System (INIS)

    Medeliene, D.

    2002-01-01

    The Decommissioning Project Management Unit team comprises western experts as well as experts from INPP Decommissioning Service who all work as a single team. The DPMU will develop the Final Decommissioning Plan and a more detailed Decommissioning Project, which will describe how the plant will be removed from service and safely decommissioned

  2. A spectral approach to compute the mean performance measures of the queue with low-order BMAP input

    Directory of Open Access Journals (Sweden)

    Ho Woo Lee

    2003-01-01

    Full Text Available This paper targets engineers and practitioners who want a simple procedure to compute the mean performance measures of the Batch Markovian Arrival process (BMAP/G/1 queueing system when the parameter matrices order is very low. We develop a set of system equations and derive the vector generating function of the queue length. Starting from the generating function, we propose a spectral approach that can be understandable to those who have basic knowledge of M/G/1 queues and eigenvalue algebra.

  3. Experiences of Fast Queue health care users in primary health care facilities in eThekwini district, South Africa.

    Science.gov (United States)

    Sokhela, Dudu G; Makhanya, Nonhlanhla J; Sibiya, Nokuthula M; Nokes, Kathleen M

    2013-07-05

    Comprehensive Primary Health Care (PHC), based on the principles of accessibility, availability, affordability, equity and acceptability, was introduced in South Africa to address inequalities in health service provision. Whilst the Fast Queue was instrumental in the promotion of access to health care, a major goal of the PHC approach, facilities were not prepared for the sudden influx of clients. Increased access resulted in long waiting times and queues contributing to dissatisfaction with the service which could lead to missed appointments and non-compliance with established treatment plans. Firstly to describe the experiences of clients using the Fast Queue strategy to access routine healthcare services and secondly, to determine how the clients' experiences led to satisfaction or dissatisfaction with the Fast Queue service. A descriptive qualitative survey using content analysis explored the experiences of the Fast Queue users in a PHC setting. Setting was first identified based on greatest number using the Fast Queue and geographic diversity and then a convenience sample of health care users of the Fast Queue were sampled individually along with one focus group of users who accessed the Queue monthly for medication refills. The same interview guide questions were used for both individual interviews and the one focus group discussion. Five clinics with the highest number of attendees during a three month period and a total of 83 health care users of the Fast Queue were interviewed. The average participant was female, 31 years old, single and unemployed. Two themes with sub-themes emerged: health care user flow and communication, which highlights both satisfaction and dissatisfaction with the fast queue and queue marshals, could assist in directing users to the respective queues, reduce waiting time and keep users satisfied with the use of sign posts where there is a lack of human resources. Effective health communication strategies contribute to positive

  4. Experiences of Fast Queue health care users in primary health care facilities in eThekwini district, South Africa

    Directory of Open Access Journals (Sweden)

    Dudu G. Sokhela

    2013-07-01

    Full Text Available Background: Comprehensive Primary Health Care (PHC, based on the principles of accessibility, availability, affordability, equity and acceptability, was introduced in South Africa to address inequalities in health service provision. Whilst the Fast Queue was instrumental in the promotion of access to health care, a major goal of the PHC approach, facilities were not prepared for the sudden influx of clients. Increased access resulted in long waiting times and queues contributing to dissatisfaction with the service which could lead to missed appointments and non-compliance with established treatment plans. Objectives: Firstly to describe the experiences of clients using the Fast Queue strategy to access routine healthcare services and secondly, to determine how the clients’ experiences led to satisfaction or dissatisfaction with the Fast Queue service. Method: A descriptive qualitative survey using content analysis explored the experiences of the Fast Queue users in a PHC setting. Setting was first identified based on greatest number using the Fast Queue and geographic diversity and then a convenience sample of health care users of the Fast Queue were sampled individually along with one focus group of users who accessed the Queue monthly for medication refills. The same interview guide questions were used for both individual interviews and the one focus group discussion. Five clinics with the highest number of attendees during a three month period and a total of 83 health care users of the Fast Queue were interviewed. The average participant was female, 31 years old, single and unemployed. Results: Two themes with sub-themes emerged: health care user flow and communication, which highlights both satisfaction and dissatisfaction with the fast queue and queue marshals, could assist in directing users to the respective queues, reduce waiting time and keep users satisfied with the use of sign posts where there is a lack of human resources

  5. The truncated Hyper-Poisson queues: Hk/Ma,b/C/N with balking, reneging and general bulk service rule

    Directory of Open Access Journals (Sweden)

    Shawky A.I.

    2008-01-01

    Full Text Available The aim of this paper is to derive the analytical solution of the queue: Hk/Ma,b/C/N with balking and reneging in which (I units arrive according to a hyper-Poisson distribution with k independent branches, (II the queue discipline is FIFO; and (III the units are served in batches according to a general bulk service rule. The steady-state probabilities, recurrence relations connecting various probabilities introduced are found and the expected number of units in the queue is derived in an explicit form. Also, some special cases are obtained. .

  6. System approach to machine building enterprise innovative activity management

    Directory of Open Access Journals (Sweden)

    І.V. Levytska

    2016-12-01

    Full Text Available The company, which operates in a challenging competitive environment should focus on new products and provide innovative services that enhance their innovation to maintain the company’s market position. The article deals with the peculiarities of such an activity in the company. The authors analyze the various approaches used in the management, and supply the advantages and disadvantages of each. It is determine that the most optimal approach among them is a system approach. The definition of the consepts "a system" and "a systematic approach to innovative activity management" are suggested. The article works out the system of machine building enterprise innovative activity management, the organization of machine building enterprise innovative activity; the planning of machine building enterprise innovative activity; the control in the system of machine building enterprise innovative activity management; the elements of the control subsystem. The properties, typical for the system of innovative management, are supplied. The managers, engaged in enterprise innovative activity management, must perform a number of the suggested tasks, which affect the efficiency of the enterprise as a whole. These exact tasks are performed using the systematic approach, providing the enterprise competitive operation and quick adaptation to changes in the external environment.

  7. Nonexercise activity thermogenesis in obesity management.

    Science.gov (United States)

    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. Copyright © 2015 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.

  8. Radioactive gaseous waste management activities at CWMF

    International Nuclear Information System (INIS)

    Sumangala, R.K; Cheralathan, M.; Hariharan, P.T.; Chitra, S.; Paul, B.

    2015-01-01

    HEPA and iodine filter banks are used as an important engineering safeguard to prevent the release of airborne activity to the environment during normal and accident conditions in all nuclear installations. CWMF is responsible for the periodical testing and certification these filter banks as per the technical specification of the nuclear facilities at Kalpakkam site. An efficiency of >99.9% is ensured for both the HEPA as well as iodine filter banks. The larger radioactive particulates are trapped in the micro glass fibre filter paper medium by the mechanism of interception and inertial impaction whereas particulates of submicron size are caught by diffusion. The major activity removed in particulate form is 137 Cs and 90 Sr. The elemental iodine is removed by physico-chemical adsorption on high surface area activated charcoal and organic compounds of iodine are removed by isotopic exchange with KI/KOH impregnated activated charcoal or silver impregnated silica gel. Silver impregnated molecular sieves 13-X and AR-1 were developed for the removal of iodine from reprocessing atmosphere. Studies on pressure swing adsorption technique have been carried out for isolating Argon from air. Using Molecular sieve 5A (45psi-50psi) and Carbon molecular sieves (100psi to 120psi) based PSA systems in series an enrichment of 30% Ar is possible. Pressurized Heavy Water Reactors with calandria vault coolant as air produces 41 Ar due to neutron activation of 40 Ar present in air which main contributor to the air is borne activity in MAPS, RAPS and Dhruva reactors. The isolated argon can be stored for decay and activity release can be minimized as per ALARA principle. (author)

  9. Past and future IAEA spent fuel management activities

    International Nuclear Information System (INIS)

    Grigoriev, A.

    1993-01-01

    The main objectives and strategies of the Agency's activities in the area of spent fuel management are to promote the exchange of information between Member States on technical, safety, environmental and economic aspects of spent fuel management technology, including storage, transport and treatment of spent fuel, and to provide assistance to Member States in the planning, implementation and operation of nuclear fuel cycle facilities. This paper give a list of the meetings held since the last issue of the Spent Fuel Management Newsletter

  10. Effectiveness of marketing in management marketing activity agricultural companies

    OpenAIRE

    KUCHER O.

    2012-01-01

    Modern approaches to evaluating the effectiveness of marketing activity are investigated. The influence of marketing expenses on actualization volume of output is analyzed. A methodical approach of defining economic efficiency in marketing sales in management business is offered.

  11. Origami: An Active Learning Exercise for Scrum Project Management

    Science.gov (United States)

    Sibona, Christopher; Pourreza, Saba; Hill, Stephen

    2018-01-01

    Scrum is a popular project management model for iterative delivery of software that subscribes to Agile principles. This paper describes an origami active learning exercise to teach the principles of Scrum in management information systems courses. The exercise shows students how Agile methods respond to changes in requirements during project…

  12. Preliminary Tritium Management Design Activities at ORNL

    International Nuclear Information System (INIS)

    Harrison, Thomas J.; Felde, David K.; Logsdon, Randall J.; McFarlane, Joanna; Qualls, A. L.

    2016-01-01

    Interest in salt-cooled and salt-fueled reactors has increased over the last decade (Forsberg et al. 2016). Several private companies and universities in the United States, as well as governments in other countries, are developing salt reactor designs and/or technology. Two primary issues for the development and deployment of many salt reactor concepts are (1) the prevention of tritium generation and (2) the management of tritium to prevent release to the environment. In 2016, the US Department of Energy (DOE) initiated a research project under the Advanced Reactor Technology Program to (1) experimentally assess the feasibility of proposed methods for tritium mitigation and (2) to perform an engineering demonstration of the most promising methods. This document describes results from the first year's efforts to define, design, and build an experimental apparatus to test potential methods for tritium management. These efforts are focused on producing a final design document as the basis for the apparatus and its scheduled completion consistent with available budget and approvals for facility use.

  13. Preliminary Tritium Management Design Activities at ORNL

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Thomas J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Felde, David K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Logsdon, Randall J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McFarlane, Joanna [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Qualls, A. L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-01

    Interest in salt-cooled and salt-fueled reactors has increased over the last decade (Forsberg et al. 2016). Several private companies and universities in the United States, as well as governments in other countries, are developing salt reactor designs and/or technology. Two primary issues for the development and deployment of many salt reactor concepts are (1) the prevention of tritium generation and (2) the management of tritium to prevent release to the environment. In 2016, the US Department of Energy (DOE) initiated a research project under the Advanced Reactor Technology Program to (1) experimentally assess the feasibility of proposed methods for tritium mitigation and (2) to perform an engineering demonstration of the most promising methods. This document describes results from the first year’s efforts to define, design, and build an experimental apparatus to test potential methods for tritium management. These efforts are focused on producing a final design document as the basis for the apparatus and its scheduled completion consistent with available budget and approvals for facility use.

  14. Optimization of Signal Timing of Intersections by Internal Metering of Queue Time Ratio of Vehicles in Network Scale

    Directory of Open Access Journals (Sweden)

    Mina Ghanbarikarekani

    2016-06-01

    Full Text Available Optimization of signal timing in urban network is usually done by minimizing the delay times or queue lengths. Sincethe effect of each intersection on the whole network is not considered in the mentioned methods, traffic congestion may occur in network links. Therefore, this paper has aimed to provide a timing optimization algorithm for traffic signals using internal timing policy based on balancing queue time ratio of vehicles in network links. In the proposed algorithm, the difference between the real queue time ratio and the optimum one for each link of intersection was minimized. To evaluate the efficiency of the proposed algorithm on traffic performance, the proposed algorithm was applied in a hypothetical network. By comparing the simulating software outputs, before and after implementing the algorithm, it was concluded that the queue time ratio algorithm has improved the traffic parameters by increasing the flow as well as reducing the delay time and density of the network.

  15. Matrix-Geometric Method for Queueing Model with State-Dependent Arrival of an Unreliable Server and PH Service

    Directory of Open Access Journals (Sweden)

    M.ReniSagaya Raj

    2016-03-01

    Full Text Available In this paper, we consider a state-dependent queueing system in which the system is subject to random breakdowns. Customer arrive at the system randomly following a Poisson process with state-dependent rates. Service times follows PH distribution and repair times are exponentially distributed. The server may fail to service with probability depending on the number of customer completed since the last repair. The main result of this paper is the matrix-geometric solution of the steady-state queue length from which many performance measurements of this queueing system like the stationary queue length distribution, waiting time distribution and the distribution of regular busy period, system utilization are obtained. Numerical examples are presented for both cases.

  16. Active Social Media Management: The Case of Health Care

    OpenAIRE

    Miller, Amalia R.; Tucker, Catherine Elizabeth

    2012-01-01

    Given the demand for authentic personal interactions over social media, it is unclear how much firms should actively manage their social media presence. We study this question empirically in a health care setting. We show that active social media management drives more user-generated content. However, we find that this is due to an incremental increase in user postings from an organization's employees rather than from its clients. This result holds when we explore exogenous variation in socia...

  17. Organizational provision of management of bank financial and economic activities

    Directory of Open Access Journals (Sweden)

    O.V. Lysenok

    2018-04-01

    Full Text Available The article deals with the organizational support of the process of management of financial and economic activities of banking institutions. In particular, the activity of one of the main divisions of the Treasury Bank, which is created and acts as an independent unit, justifies the decision to make certain financial transactions on the relevant financial markets and manages cash flows through interaction with branches, departments and offices of the banking institution. The article also focuses on the problem of the lack of accurate and up-to-date information between the structural units that take part in the management of the finances of the banking institution. In connection with this, it is necessary to create an information and management field of the bank, which is a collection of organized information input and output flows on the financial and economic activities of the bank, forming a unified management information about the financial activities of the banking institution. The article also focuses on the concept of the creation of an informational and managerial tree, according to which, in the structure of management of financial and economic activity of a banking institution, it is necessary to allocate five levels, based on which the principle of obligatory passage of necessary information at all levels with a gradual systematization and generalization. The concept considered in the article gives an idea of the logic and methodology of creating the process of forming general managerial decisions regarding the financial and economic activity of the bank in the future.

  18. Cost Comparison of B-1B Non-Mission-Capable Drivers Using Finite Source Queueing with Spares

    Science.gov (United States)

    2012-09-06

    COMPARISON OF B-1B NON-MISSION-CAPABLE DRIVERS USING FINITE SOURCE QUEUEING WITH SPARES GRADUATE RESEARCH PAPER Presented to the Faculty...step into the lineup making large-number approximations unusable. Instead, a finite source queueing model including spares is incorporated...were reported as flying time accrued since last occurrence. Service time was given in both start-stop format and MX man-hours utilized. Service time was

  19. Active listening: The key of successful communication in hospital managers.

    Science.gov (United States)

    Jahromi, Vahid Kohpeima; Tabatabaee, Seyed Saeed; Abdar, Zahra Esmaeili; Rajabi, Mahboobeh

    2016-03-01

    One of the important causes of medical errors and unintentional harm to patients is ineffective communication. The important part of this skill, in case it has been forgotten, is listening. The objective of this study was to determine whether managers in hospitals listen actively. This study was conducted between May and June 2014 among three levels of managers at teaching hospitals in Kerman, Iran. Active Listening skill among hospital managers was measured by self-made Active Listening Skill Scale (ALSS), which consists of the key elements of active listening and has five subscales, i.e., Avoiding Interruption, Maintaining Interest, Postponing Evaluation, Organizing Information, and Showing Interest. The data were analyzed by IBM-SPSS software, version 20, and the Pearson product-moment correlation coefficient, the chi-squared test, and multiple linear regressions. The mean score of active listening in hospital managers was 2.32 out of 3.The highest score (2.27) was obtained by the first-level managers, and the top managers got the lowest score (2.16). Hospital mangers were best in showing interest and worst in avoiding interruptions. The area of employment was a significant predictor of avoiding interruption and the managers' gender was a strong predictor of skill in maintaining interest (p < 0.05). The type of management and education can predict postponing evaluation, and the length of employment can predict showing interest (p < 0.05). There is a necessity for the development of strategies to create more awareness among the hospital managers concerning their active listening skills.

  20. Management information systems for environmental compliance activities

    Energy Technology Data Exchange (ETDEWEB)

    1990-04-23

    The Department of Energy (DOE) is subject to Federal and state laws designed to protect against threats to public health and the environment. The purpose of this audit was to determine whether the Department had developed adequate information systems for tracking and reporting on the status of its compliance with these laws. Systems used for prioritizing and budgeting for environmental activities are being addressed in a separate review.

  1. Management of maintenance activities at Cernavoda NPP

    International Nuclear Information System (INIS)

    Riedel, M.; Urjan, R.; Marinescu, S.; Corlan, L.

    2000-01-01

    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)

  2. Factors Affecting Number of Diabetes Management Activities Provided by Pharmacists.

    Science.gov (United States)

    Lo, Annie; Lorenz, Kathleen; Cor, Ken; Simpson, Scot H

    2016-12-01

    Legislative changes since 2007 have given Alberta pharmacists additional authorizations and new practice settings, which should enhance provision of clinical services to patients. This study examined whether these changes are related to the number of diabetes management activities provided by pharmacists. Cross-sectional surveys of Alberta pharmacists were conducted in 2006 and 2015. Both questionnaires contained 63 diabetes management activities, with response options to indicate how frequently the activity was provided. Respondents were grouped by survey year, practice setting, diabetes-specific training and additional authorizations. The number of diabetes management activities provided often or always were compared among groups by using analysis of variance. Data from 128 pharmacists participating in the 2006 survey were compared with 256 pharmacists participating in the 2015 survey; overall mean age was 41.6 (±10.9) years, 245 (64%) were women, mean duration of practice was 16.1 (±11.8) years, 280 (73%) were community pharmacists, 75 (20%) were certified diabetes educators (CDEs), and 100 (26%) had additional prescribing authorization (APA). Pharmacists provided a mean of 28.7 (95% CI 26.3 to 31.2) diabetes management activities in 2006 and 35.2 (95% CI 33.4-37.0) activities in 2015 (p<0.001). Pharmacists who were CDEs provided significantly more activities compared to other pharmacists (p<0.001). In 2015, working in a primary care network and having APA were also associated with provision of more activities (p<0.05 for both comparisons). Pharmacists provided more diabetes management activities in 2015 than in 2006. The number of diabetes management activities was also associated with being a CDE, working in a primary care network or having APA. Copyright © 2016 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.

  3. Application of Queueing Theory to the Analysis of Changes in Outpatients' Waiting Times in Hospitals Introducing EMR.

    Science.gov (United States)

    Cho, Kyoung Won; Kim, Seong Min; Chae, Young Moon; Song, Yong Uk

    2017-01-01

    This research used queueing theory to analyze changes in outpatients' waiting times before and after the introduction of Electronic Medical Record (EMR) systems. We focused on the exact drawing of two fundamental parameters for queueing analysis, arrival rate (λ) and service rate (µ), from digital data to apply queueing theory to the analysis of outpatients' waiting times. We used outpatients' reception times and consultation finish times to calculate the arrival and service rates, respectively. Using queueing theory, we could calculate waiting time excluding distorted values from the digital data and distortion factors, such as arrival before the hospital open time, which occurs frequently in the initial stage of a queueing system. We analyzed changes in outpatients' waiting times before and after the introduction of EMR using the methodology proposed in this paper, and found that the outpatients' waiting time decreases after the introduction of EMR. More specifically, the outpatients' waiting times in the target public hospitals have decreased by rates in the range between 44% and 78%. It is possible to analyze waiting times while minimizing input errors and limitations influencing consultation procedures if we use digital data and apply the queueing theory. Our results verify that the introduction of EMR contributes to the improvement of patient services by decreasing outpatients' waiting time, or by increasing efficiency. It is also expected that our methodology or its expansion could contribute to the improvement of hospital service by assisting the identification and resolution of bottlenecks in the outpatient consultation process.

  4. Current Management Strategy for Active Surveillance in Prostate Cancer.

    Science.gov (United States)

    Syed, Jamil S; Javier-Desloges, Juan; Tatzel, Stephanie; Bhagat, Ansh; Nguyen, Kevin A; Hwang, Kevin; Kim, Sarah; Sprenkle, Preston C

    2017-02-01

    Active surveillance has been increasingly utilized as a strategy for the management of favorable-risk, localized prostate cancer. In this review, we describe contemporary management strategies of active surveillance, with a focus on traditional stratification schemes, new prognostic tools, and patient outcomes. Patient selection, follow-up strategy, and indication for delayed intervention for active surveillance remain centered around PSA, digital rectal exam, and biopsy findings. Novel tools which include imaging, biomarkers, and genetic assays have been investigated as potential prognostic adjuncts; however, their role in active surveillance remains institutionally dependent. Although 30-50% of patients on active surveillance ultimately undergo delayed treatment, the vast majority will remain free of metastasis with a low risk of dying from prostate cancer. The optimal method for patient selection into active surveillance is unknown; however, cancer-specific mortality rates remain excellent. New prognostication tools are promising, and long-term prospective, randomized data regarding their use in active surveillance will be beneficial.

  5. Short communication: Biochemically active humic substances in contrasting agricultural managements

    Directory of Open Access Journals (Sweden)

    Emilio Benitez

    2016-08-01

    Full Text Available Because their crucial role in several soil biochemical cycles and their fast response to changes in soil management, extracellular enzymes activities are widely used as sensitive indicators of ecological change and soil quality. The aim of this work was to determine the effects of soil management on the stable pool of soil carbon cycling enzymes as indicators of essential functions. For this, extracellular β-glucosidase enzymes bounded by humic acids (C higher than 104 Da were used to compare four long-term contrasting agricultural managements in a rainfed olive orchard representative of semi-arid Mediterranean habitats. The study was conducted for 30 years by designing a random-block of four treatments (nude vs. covered soils and four replicates. Maintaining cover crops through fall, winter and early spring provoked a more stable and active pool of extracellular β-glucosidase in soils only if spontaneous vegetation was managed with mechanical methods. When herbicides were used during 30 years, the pattern of the molecular composition and activity of humus β-glucosidase complexes were similar in covered and nude soils, although higher activity was retrieved in the former. Tillage management increased carbon mineralization and the level of humic substances and the activity of β-glucosidase humic-bound were quite lower than in the rest of treatments. Given the ecological role of extracellular soil carbon cycling enzymes, the characterization of humus β-glucosidase complexes could be an adequate indicator of sustainability of agricultural management systems.

  6. Short communication: Biochemically active humic substances in contrasting agricultural managements

    Energy Technology Data Exchange (ETDEWEB)

    Benitez, E.; Nogales, R.; Doni, S.; Masciandaro, G.; Moreno, B.

    2016-11-01

    Because their crucial role in several soil biochemical cycles and their fast response to changes in soil management, extracellular enzymes activities are widely used as sensitive indicators of ecological change and soil quality. The aim of this work was to determine the effects of soil management on the stable pool of soil carbon cycling enzymes as indicators of essential functions. For this, extracellular β-glucosidase enzymes bounded by humic acids (C higher than 104 Da) were used to compare four long-term contrasting agricultural managements in a rainfed olive orchard representative of semi-arid Mediterranean habitats. The study was conducted for 30 years by designing a random-block of four treatments (nude vs. covered soils) and four replicates. Maintaining cover crops through fall, winter and early spring provoked a more stable and active pool of extracellular β-glucosidase in soils only if spontaneous vegetation was managed with mechanical methods. When herbicides were used during 30 years, the pattern of the molecular composition and activity of humus β-glucosidase complexes were similar in covered and nude soils, although higher activity was retrieved in the former. Tillage management increased carbon mineralization and the level of humic substances and the activity of β-glucosidase humic-bound were quite lower than in the rest of treatments. Given the ecological role of extracellular soil carbon cycling enzymes, the characterization of humus β-glucosidase complexes could be an adequate indicator of sustainability of agricultural management systems. (Author)

  7. BATAN Activities in Developing Nuclear Knowledge Management

    International Nuclear Information System (INIS)

    Darmawati, S.

    2016-01-01

    Full text: BATAN (National Atomic Energy Agency of Indonesia) was established in 1964, and after the issuance of Law 10 of 1997 it become National Nuclear Energy Agency. During the last seven years, BATAN has suffered the loss of many of its valuable human resources due to the zero-growth policy of the government in recruiting new staffs. The uncertain future of nuclear power programme in Indonesia has also reduced the interest of young generation to study nuclear related subjects, resulting in the closing of several departments in universities that once offered nuclear sciences as subject of studies. These situations triggered management of BATAN to develop various efforts to keep nuclear knowledge exist and disseminate among BATAN itself, university students, and public as a whole. BATAN has in recent years established higher school of nuclear technology and organized various nuclear related training programmes, and also in cooperation with other governmental organizations establish nuclear zones, nuclear information centres and nuclear corners in public as well as in high school areas throughout Indonesia. All these efforts are aimed to transfer and preserve nuclear knowledge for the better future of the applications of nuclear science and technology in Indonesia. (author

  8. Analysis of queueing system with discrete autoregressive arrivals having DML as marginal distribution

    Directory of Open Access Journals (Sweden)

    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.

  9. On buffer overflow duration in a finite-capacity queueing system with multiple vacation policy

    Science.gov (United States)

    Kempa, Wojciech M.

    2017-12-01

    A finite-buffer queueing system with Poisson arrivals and generally distributed processing times, operating under multiple vacation policy, is considered. Each time when the system becomes empty, the service station takes successive independent and identically distributed vacation periods, until, at the completion epoch of one of them, at least one job waiting for service is detected in the buffer. Applying analytical approach based on the idea of embedded Markov chain, integral equations and linear algebra, the compact-form representation for the cumulative distribution function (CDF for short) of the first buffer overflow duration is found. Hence, the formula for the CDF of next such periods is obtained. Moreover, probability distributions of the number of job losses in successive buffer overflow periods are found. The considered queueing system can be efficienly applied in modelling energy saving mechanisms in wireless network communication.

  10. A discrete-time queueing system with changes in the vacation times

    Directory of Open Access Journals (Sweden)

    Atencia Ivan

    2016-06-01

    Full Text Available This paper considers a discrete-time queueing system in which an arriving customer can decide to follow a last come first served (LCFS service discipline or to become a negative customer that eliminates the one at service, if any. After service completion, the server can opt for a vacation time or it can remain on duty. Changes in the vacation times as well as their associated distribution are thoroughly studied. An extensive analysis of the system is carried out and, using a probability generating function approach, steady-state performance measures such as the first moments of the busy period of the queue content and of customers delay are obtained. Finally, some numerical examples to show the influence of the parameters on several performance characteristics are given.

  11. A Discrete-Time Geo/G/1 Retrial Queue with Two Different Types of Vacations

    Directory of Open Access Journals (Sweden)

    Feng Zhang

    2015-01-01

    Full Text Available We analyze a discrete-time Geo/G/1 retrial queue with two different types of vacations and general retrial times. Two different types of vacation policies are investigated in this model, one of which is nonexhaustive urgent vacation during serving and the other is normal exhaustive vacation. For this model, we give the steady-state analysis for the considered queueing system. Firstly, we obtain the generating functions of the number of customers in our model. Then, we obtain the closed-form expressions of some performance measures and also give a stochastic decomposition result for the system size. Moreover, the relationship between this discrete-time model and the corresponding continuous-time model is also investigated. Finally, some numerical results are provided to illustrate the effect of nonexhaustive urgent vacation on some performance characteristics of the system.

  12. A Discrete-Time Queue with Balking, Reneging, and Working Vacations

    Directory of Open Access Journals (Sweden)

    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.

  13. Freeway Traffic Density and On-Ramp Queue Control via ILC Approach

    Directory of Open Access Journals (Sweden)

    Ronghu Chi

    2014-01-01

    Full Text Available A new queue length information fused iterative learning control approach (QLIF-ILC is presented for freeway traffic ramp metering to achieve a better performance by utilizing the error information of the on-ramp queue length. The QLIF-ILC consists of two parts, where the iterative feedforward part updates the control input signal by learning from the past control data in previous trials, and the current feedback part utilizes the tracking error of the current learning iteration to stabilize the controlled plant. These two parts are combined in a complementary manner to enhance the robustness of the proposed QLIF-ILC. A systematic approach is developed to analyze the convergence and robustness of the proposed learning scheme. The simulation results are further given to demonstrate the effectiveness of the proposed QLIF-ILC.

  14. Fast distributed strategic learning for global optima in queueing access games

    KAUST Repository

    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.

  15. Impact of sensing errors on the queueing delay and transmit power in cognitive radio access

    KAUST Repository

    Hamza, Doha R.; Aissa, Sonia

    2011-01-01

    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.

  16. The queueing perspective of asynchronous network coding in two-way relay network

    Science.gov (United States)

    Liang, Yaping; Chang, Qing; Li, Xianxu

    2018-04-01

    Asynchronous network coding (NC) has potential to improve the wireless network performance compared with a routing or the synchronous network coding. Recent researches concentrate on the optimization between throughput/energy consuming and delay with a couple of independent input flow. However, the implementation of NC requires a thorough investigation of its impact on relevant queueing systems where few work focuses on. Moreover, few works study the probability density function (pdf) in network coding scenario. In this paper, the scenario with two independent Poisson input flows and one output flow is considered. The asynchronous NC-based strategy is that a new arrival evicts a head packet holding in its queue when waiting for another packet from the other flow to encode. The pdf for the output flow which contains both coded and uncoded packets is derived. Besides, the statistic characteristics of this strategy are analyzed. These results are verified by numerical simulations.

  17. A finite capacity queue with Markovian arrivals and two servers with group services

    Directory of Open Access Journals (Sweden)

    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.

  18. The MAP, M/G1,G2/1 queue with preemptive priority

    Directory of Open Access Journals (Sweden)

    Bong Dae Choi

    1997-01-01

    Full Text Available We consider the MAP, M/G1,G2/1 queue with preemptive resume priority, where low priority customers arrive to the system according to a Markovian arrival process (MAP and high priority customers according to a Poisson process. The service time density function of low (respectively: high priority customers is g1(x (respectively: g2(x. We use the supplementary variable method with Extended Laplace Transforms to obtain the joint transform of the number of customers in each priority queue, as well as the remaining service time for the customer in service in the steady state. We also derive the probability generating function for the number of customers of low (respectively, high priority in the system just after the service completion epochs for customers of low (respectively, high priority.

  19. Impact of sensing errors on the queueing delay and transmit power in cognitive radio access

    KAUST Repository

    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.

  20. Improved diagonal queue medical image steganography using Chaos theory, LFSR, and Rabin cryptosystem.

    Science.gov (United States)

    Jain, Mamta; Kumar, Anil; Choudhary, Rishabh Charan

    2017-06-01

    In this article, we have proposed an improved diagonal queue medical image steganography for patient secret medical data transmission using chaotic standard map, linear feedback shift register, and Rabin cryptosystem, for improvement of previous technique (Jain and Lenka in Springer Brain Inform 3:39-51, 2016). The proposed algorithm comprises four stages, generation of pseudo-random sequences (pseudo-random sequences are generated by linear feedback shift register and standard chaotic map), permutation and XORing using pseudo-random sequences, encryption using Rabin cryptosystem, and steganography using the improved diagonal queues. Security analysis has been carried out. Performance analysis is observed using MSE, PSNR, maximum embedding capacity, as well as by histogram analysis between various Brain disease stego and cover images.

  1. Activity-Based Costing: A Cost Management Tool.

    Science.gov (United States)

    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)

  2. A Two-Stage Queue Model to Optimize Layout of Urban Drainage System considering Extreme Rainstorms

    OpenAIRE

    He, Xinhua; Hu, Wenfa

    2017-01-01

    Extreme rainstorm is a main factor to cause urban floods when urban drainage system cannot discharge stormwater successfully. This paper investigates distribution feature of rainstorms and draining process of urban drainage systems and uses a two-stage single-counter queue method M/M/1→M/D/1 to model urban drainage system. The model emphasizes randomness of extreme rainstorms, fuzziness of draining process, and construction and operation cost of drainage system. Its two objectives are total c...

  3. Analysis of MAP/PH(1, PH(2/2 Queue with Bernoulli Vacations

    Directory of Open Access Journals (Sweden)

    V. Thangaraj

    2008-12-01

    Full Text Available We consider a two-heterogeneous-server queueing system with Bernoulli vacation in which customers arrive according to a Markovian arrival process (MAP. Servers returning from vacation immediately take another vacation if no customer is waiting. Using matrix-geometric method, the steady-state probability of the number of customers in the system is investigated. Some important performance measures are obtained. The waiting time distribution and the mean waiting time are also discussed. Finally, some numerical illustrations are provided.

  4. Tool supported modeling of sensor communication networks by using finite-source priority retrial queues

    Directory of Open Access Journals (Sweden)

    Tamas Berczes

    2012-06-01

    Full Text Available The main aim of the present paper is to draw the attention of the readers of this special issue to the modeling issues of sensor networks. The novelty of this investigation is the introduction of servers vacation combined with priority customers for finite-source retrial queues and its application to wireless sensor networks. In this paper we analyze a priority finite-source retrial queue with repeated vacations. Two types of priority customers are defined, customers with priority 1 (P1 go directly to an ordinary FIFO queue. However, if customers with priority 2 (P2 find the server in busy or unavailable state go to the orbit. These customers stay in the orbit and retry their request until find the server in idle and available state. We assume that P1 customers have non-preemptive priority over P2 customers. The server starts with a listening period and if no customer arrive during this period it will enter in the vacation mode. When the vacation period is terminated, then the node wakes up. If there is a P1 customer in the queue the server begin to serve it, and when there is no any P1 customer, the node will remain awake for exponentially distributed time period. If that period expires without arrivals the node will enter in the next sleeping period. All random variables involved in model construction are supposed to be independent and exponentially distributed ones. Our main interest is to give the main steady-state performance measures of the system computed by the help of the MOSEL tool. Several Figures illustrate the effect of input parameters on the mean response time.

  5. On one problem of the busy period determination in queues with infinitely many servers

    International Nuclear Information System (INIS)

    Dvurecenskij, A.; Kuljukina, L.A.; Ososkov, G.A.

    1982-01-01

    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

  6. ANALYSIS OF FUZZY QUEUES: PARAMETRIC PROGRAMMING APPROACH BASED ON RANDOMNESS - FUZZINESS CONSISTENCY PRINCIPLE

    OpenAIRE

    Dhruba Das; Hemanta K. Baruah

    2015-01-01

    In this article, based on Zadeh’s extension principle we have apply the parametric programming approach to construct the membership functions of the performance measures when the interarrival time and the service time are fuzzy numbers based on the Baruah’s Randomness- Fuzziness Consistency Principle. The Randomness-Fuzziness Consistency Principle leads to defining a normal law of fuzziness using two different laws of randomness. In this article, two fuzzy queues FM...

  7. The busy period of order n in the GI/D/infinity queue

    International Nuclear Information System (INIS)

    Dvurecenskij, A.

    1982-01-01

    The problem of determination of the distribution function, integral equation and all moments of the busy period of order n, that is, the period when at least n servers are busy from infinitely many servers of the GI/D/infinity queueing system are investigated. The idle period of order n, i. e., the period between two neighbouring busy periods of order n is also studied. Those problems arise in the blob length determination in track chambers in high energy physics

  8. Stochastic Analysis of a Queue Length Model Using a Graphics Processing Unit

    Czech Academy of Sciences Publication Activity Database

    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

  9. What money can't buy: allocations with priority lists, lotteries and queues

    OpenAIRE

    Daniele Condorelli

    2009-01-01

    I study the welfare optimal allocation of a number of identical and indivisible objects to a set of heterogeneous risk-neutral agents under the hypothesis that money is not available. Agents have independent private values, which represent the maximum time that they are will- ing to wait in line to obtain a good. A priority list, which ranks agents according to their expected values, is optimal when hazard rates of the distributions of values are increasing. Queues, which allocates the ob- je...

  10. [Active career management needed for female doctors].

    Science.gov (United States)

    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.

  11. Modeling Message Queueing Services with Reliability Guarantee in Cloud Computing Environment Using Colored Petri Nets

    Directory of Open Access Journals (Sweden)

    Jing Li

    2015-01-01

    Full Text Available Motivated by the need for loosely coupled and asynchronous dissemination of information, message queues are widely used in large-scale application areas. With the advent of virtualization technology, cloud-based message queueing services (CMQSs with distributed computing and storage are widely adopted to improve availability, scalability, and reliability; however, a critical issue is its performance and the quality of service (QoS. While numerous approaches evaluating system performance are available, there is no modeling approach for estimating and analyzing the performance of CMQSs. In this paper, we employ both the analytical and simulation modeling to address the performance of CMQSs with reliability guarantee. We present a visibility-based modeling approach (VMA for simulation model using colored Petri nets (CPN. Our model incorporates the important features of message queueing services in the cloud such as replication, message consistency, resource virtualization, and especially the mechanism named visibility timeout which is adopted in the services to guarantee system reliability. Finally, we evaluate our model through different experiments under varied scenarios to obtain important performance metrics such as total message delivery time, waiting number, and components utilization. Our results reveal considerable insights into resource scheduling and system configuration for service providers to estimate and gain performance optimization.

  12. State dependent arrival in bulk retrial queueing system with immediate Bernoulli feedback, multiple vacations and threshold

    Science.gov (United States)

    Niranjan, S. P.; Chandrasekaran, V. M.; Indhira, K.

    2017-11-01

    The objective of this paper is to analyse state dependent arrival in bulk retrial queueing system with immediate Bernoulli feedback, multiple vacations, threshold and constant retrial policy. Primary customers are arriving into the system in bulk with different arrival rates λ a and λ b . If arriving customers find the server is busy then the entire batch will join to orbit. Customer from orbit request service one by one with constant retrial rate γ. On the other hand if an arrival of customers finds the server is idle then customers will be served in batches according to general bulk service rule. After service completion, customers may request service again with probability δ as feedback or leave from the system with probability 1 - δ. In the service completion epoch, if the orbit size is zero then the server leaves for multiple vacations. The server continues the vacation until the orbit size reaches the value ‘N’ (N > b). At the vacation completion, if the orbit size is ‘N’ then the server becomes ready to provide service for customers from the main pool or from the orbit. For the designed queueing model, probability generating function of the queue size at an arbitrary time will be obtained by using supplementary variable technique. Various performance measures will be derived with suitable numerical illustrations.

  13. Dynamic Performance Optimization for Cloud Computing Using M/M/m Queueing System

    Directory of Open Access Journals (Sweden)

    Lizheng Guo

    2014-01-01

    Full Text Available Successful development of cloud computing has attracted more and more people and enterprises to use it. On one hand, using cloud computing reduces the cost; on the other hand, using cloud computing improves the efficiency. As the users are largely concerned about the Quality of Services (QoS, performance optimization of the cloud computing has become critical to its successful application. In order to optimize the performance of multiple requesters and services in cloud computing, by means of queueing theory, we analyze and conduct the equation of each parameter of the services in the data center. Then, through analyzing the performance parameters of the queueing system, we propose the synthesis optimization mode, function, and strategy. Lastly, we set up the simulation based on the synthesis optimization mode; we also compare and analyze the simulation results to the classical optimization methods (short service time first and first in, first out method, which show that the proposed model can optimize the average wait time, average queue length, and the number of customer.

  14. A spatiotemporal model for the LTE uplink: Spatially interacting tandem queues approach

    KAUST Repository

    Gharbieh, Mohammad

    2017-07-31

    With the proliferation of the Internet-of-things (IoT), there is an undeniable consensus that cellular LTE networks will have to support a dramatically larger number of uplink connections. This is true since most of the devices to be added incur machine-type communications which is dominantly upstream. Can current LTE network withstand this challenge? To answer this question, the joint performance of random access process and the uplink data transmission should be investigated. These two problems have been classically treated in the literature in a disjoint fashion. In this paper, they are jointly analyzed as an inseparable couple. To do that, a tandem queuing model is adopted whereby devices are represented as spatially interacting queues. The interaction between queues is governed by the mutual inter-cell and intra-cell interference. To that end, a joint stochastic geometry and queueing theory model is exploited to study this problem and a spatiotemporal analytical model is developed accordingly. Network stability and scalability are two prime performance criteria for performance assessment. In light of these two criteria, the developed model is poised to offer valuable insights into efficient access and resource allocation strategies.

  15. A queueing theory description of fat-tailed price returns in imperfect financial markets

    Science.gov (United States)

    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.

  16. ICIT activities related to tritium management

    International Nuclear Information System (INIS)

    Zamfirache, Marius; Bornea, Anisia; Stefanescu, Ioan; Ana, George; Stefan, Liviu

    2016-01-01

    Highlights: • We present the main directions of ICIT research in the field of hydrogen isotopes. • Tritium Removal Facility became a nuclear installation. • ICIT had begun the transfer of detritiation technology. - Abstract: National Research and Development Institute for Cryogenics and Isotopic Technologies (ICIT) was established in 1970 as a research focused Industrial Pilot Plant. This new Institute was created with the purpose to develop the heavy water production technology. This technology has been successfully transferred to the heavy water production plant in 1988 (with a capacity of 360 t/year). Currently, research within ICIT is focused on the following main objectives: support for the National Nuclear Program, hydrogen and fuel cells, cryogenics, environment. Within ICIT it has been built an Experimental Pilot Plant having as the main objective the development of a technology for heavy water detritiation. The purpose of this Pilot Plant is to obtain technological data and functional characteristics of specific equipment in order to design a Detritiation Facility used for Nuclear Power Plants with CANDU reactors. This work is focused on the presentation of ICIT research activities, perspectives and its capability related to water detritiation technologies and also to on issues in the field of nuclear fusion.

  17. Air Force Supply Management Analysis of Activity Groups Financial Reports, Prices, and Cash Management

    National Research Council Canada - National Science Library

    1998-01-01

    The Air Force supply management activity group provides about two million types of inventory items, including weapon system spare parts, fuels, and medical-dental supplies, to customers which consist...

  18. Using Sales Management Students to Manage Professional Selling Students in an Innovative Active Learning Project

    Science.gov (United States)

    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…

  19. Buffer management in wireless full-duplex systems

    KAUST Repository

    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.

  20. Knowledge Management Tools in Application to Regulatory Body Activity

    International Nuclear Information System (INIS)

    Volkov, E.

    2016-01-01

    Full text: The paper presents the application of knowledge management tools to regulatory authority activity. Knowledge management tools are considered a means for improving the efficiency of regulator activities. Three case studies are considered: 1. a knowledge management audit procedure in the regulator (tools for knowledge management audit application, results and the audit outcomes); 2. the development of a guide to identify causes of discrepancies and shortcomings revealed during inspections in NPP maintenance (ontologies of factors influencing on a maintenance quality and causes of discrepancies and shortcoming development); 3. the development of a knowledge portal for regulator (regulator needs which could be covered by the portal, definition and basic function of the portal, it’s functioning principles, development goals and tasks, common model, development stages). (author)

  1. In-core fuel management activities in China

    International Nuclear Information System (INIS)

    Ruan Keqiang; Chen Renji; Hu Chuanwen

    1990-01-01

    The development of nuclear power in China has reached such a stage that PWR in-core fuel management becomes an urgent problem. At present the main effort is concentrated on solving the Qinshan nuclear power plant and Daya Bay nuclear power plant fuel management problems. For the Qinshan PWR (300 MWe) two packages of in-core fuel management code were developed, one with simplified nodal diffusion method and the other uses advanced Green's function nodal method. Both were used in the PWR core design. With the help of the two code packages first two cycles of the Qinshan PWR core burn-up were calculated. Besides, several research works are under way in the following areas: improvement of the nodal diffusion method and other coarse mesh method in terms of computing speed and accuracy; backward diffusion technique for fuel management application; optimization technique in the fuel loading pattern searching. As for the Daya Bay PWR plant (twin 900 MWe unit), the problem about using what kind of code package for in-core fuel management is still under discussion. In principle the above mentioned code packages are also applicable to it. Besides PWR, in-core fuel management research works are also under way for research reactors, for example, heavy water research reactor and high flux research reactor in some institutes in China. China also takes active participation in international in-core fuel management activities. (author). 19 refs

  2. "A Separation Theorem of Active Management and Synthetic Enhanced Active Strategies"(in Japanese)

    OpenAIRE

    Takao Kobayashi; Seiji Minami

    2008-01-01

    We propose a Separation Theorem of Active Management. It asserts that in the so-called Enhanced Active Portfolio framework the efficient frontier is linear in the active return/active risk space, and one can separate the determination of optimal active portfolio weights from the determination of optimal leverage ratio. The risk preference of investors does not play any role in the former decision. The theorem holds under a fairly general set of conditions on portfolio restrictions. As such it...

  3. Vehicle routing with dynamic travel times : a queueing approach

    NARCIS (Netherlands)

    Woensel, van T.; Kerbache, L.; Peremans, H.; Vandaele, N.J.

    2008-01-01

    Transportation is an important component of supply chain competitiveness since it plays a major role in the inbound, inter-facility, and outbound logistics. In this context, assigning and scheduling vehicle routes is a crucial management problem. In this paper, a vehicle routing problem with dynamic

  4. Training to Support Standardization and Improvement of Configuration Management Activities

    Energy Technology Data Exchange (ETDEWEB)

    Dauber, V.; Scheffer, N.; Schoenfelder, C.

    2015-07-01

    In recent years AREVA has conducted several measures to enhance the effectiveness and efficiency of configuration management-related activities within a nuclear power plant (NPP) new build as well as modernization projects, thereby further strengthening its commitment to achieving the highest level of safety in nuclear facilities. This paper describes a new training course that shall support the standardization and improvement of configuration management activities. Recommendations will be given that should be considered when designing and developing comparable training programs to support change processes within engineering units. (Author)

  5. WAX ActiveLibrary: a tool to manage information overload.

    Science.gov (United States)

    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.

  6. Management system of in vivo reports of activity measurements

    International Nuclear Information System (INIS)

    Castro, R.C.; Dantas, A.L.A.; Lourenco, M.C.; Dantas, B.M.

    2005-01-01

    The SGRIMA (management system of in vivo reports of activity measurements) is a software for Windows developed specifically for the Laboratory of In Vivo Measurements of the IRD - Brazilian Institute for Radioprotection and Dosimetry -, in order to manage the individual monitoring process that includes personal data archiving, data relating to the parameters of each measure and calculation results of activity. The software was developed in MS Visual Basic 6, using a MS Access database and can be run on personal computers with MS Windows 98 or higher

  7. IAEA activities in the field of NPP life management

    International Nuclear Information System (INIS)

    Gueorguiev, B.; Lyssakov, V.; Davies, L.M.

    1997-01-01

    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

  8. IAEA activities in the field of NPP life management

    Energy Technology Data Exchange (ETDEWEB)

    Gueorguiev, B; Lyssakov, V; Davies, L M

    1997-09-01

    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.

  9. Contributions for territorial management of risks associated with oil activity

    Directory of Open Access Journals (Sweden)

    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

  10. Management of spent high activity radioactive sources (SHARS)

    International Nuclear Information System (INIS)

    2002-09-01

    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

  11. "Can You Repeat That?" Teaching Active Listening in Management Education

    Science.gov (United States)

    Spataro, Sandra E.; Bloch, Janel

    2018-01-01

    Listening is a critical communication skill and therefore an essential element of management education. "Active" listening surpasses passive listening or simple hearing to establish a deeper connection between speaker and listener, as the listener gives the speaker full attention via inquiry, reflection, respect, and empathy. This…

  12. Draft position paper on knowledge management in space activities

    Science.gov (United States)

    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.

  13. This is how we manage Sweden's radioactive waste. Activities 1995

    International Nuclear Information System (INIS)

    1996-01-01

    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

  14. How an Active Learning Classroom Transformed IT Executive Management

    Science.gov (United States)

    Connolly, Amy; Lampe, Michael

    2016-01-01

    This article describes how our university built a unique classroom environment specifically for active learning. This classroom changed students' experience in the undergraduate executive information technology (IT) management class. Every college graduate should learn to think critically, solve problems, and communicate solutions, but 90% of…

  15. Dose Determination of Activated Charcoal in Management of ...

    African Journals Online (AJOL)

    Purpose: To assess the doses of activated charcoal currently used in the management of acute amitriptyline-induced drug poisoning and explore the possibility of using lower doses. Methods: Albino male Wistar rats, weighing 200 ± 20 g, were used for the study. The animals were divided into four groups of eight animals ...

  16. Study on Total Quality Management Activities in Taiwan Tourism Factories

    Directory of Open Access Journals (Sweden)

    Yi-Chan Chung

    2016-08-01

    Full Text Available As competition becomes increasingly fierce, how to integrate the concept of information technology involvement into total quality management activities and better serve the customers, thus increasing the effectiveness of their services, has become an important focus for many tourism factories in their selection of an appropriate operational strategy. With the tourism factories in Taiwan as the subjects, this study was therefore set out to investigate the impact of operational strategies, information technology involvement and motivation on the executive degree of total quality management (TQM activities, as well as the correlation between the executive degree of TQM activities and operational performance. This research was conducted from March to April 2016 using 56 effective questionnaires through a questionnaire survey method. According to the research findings, the higher the executive degree of TQM activities was, the more significant a positive impact it would have on operational performance; the execution of differentiation strategies would have a positive impact on the execution of TQM activities; the more a company was involved in information technology, the more significant a positive impact it would have on the execution of TQM activities; the higher the intrinsic motivation was, the more significant a positive impact it would have on the executive degrees of TQM activities. It is therefore advisable for tourism factories to implement TQM activities, adopt differentiation strategies, seek greater information technology involvement and become more strongly motivated toward TQM implementation in order to improve operational performance.

  17. Capacity Planning and Leadtime management

    NARCIS (Netherlands)

    Zijm, Willem H.M.; Buitenhek, R.

    1996-01-01

    In this paper we discuss a framework for capacity planning and lead time management in manufacturing companies, with an emphasis on the machine shop. First we show how queueing models can be used to find approximations of the mean and the variance of manufacturing shop lead times. These quantities

  18. System-functional approach in enterprise''s innovation activity management

    OpenAIRE

    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.

  19. Clinical management of musculoskeletal injuries in active children and youth.

    Science.gov (United States)

    Mazer, Barbara; Shrier, Ian; Feldman, Debbie Ehrmann; Swaine, Bonnie; Majnemer, Annette; Kennedy, Eileen; Chilingaryan, Gevorg

    2010-07-01

    To describe how different health care specialists manage musculoskeletal injury in children and examine factors influencing return to play decisions. National survey. Secure Web site hosting online questionnaire. Medical doctors, physical therapists, and athletic therapists who were members of their respective sport medicine specialty organizations. Professional affiliation and the effect of the following factors were examined: pushy parent, cautious parent, protective equipment, previous injury, musculoskeletal maturity, game importance, position played, team versus individual sport, and time since injury. Recommendation of return to activity after common injuries seen in children and adolescents as described in 5 vignettes; consistency of responses across vignettes. The survey was completed by 464 respondents (34%). There were several differences between the professional groups in their recommendations to return to activity. Most factors studied did not tend to influence the decision to return to activity, although protective equipment often increased the response to return sooner. The number of participants who would return a child to activity sooner or later for each factor varied greatly across the 5 vignettes, except for pushy parent or cautious parent. Management practices of sport medicine clinicians vary according to profession, child, clinical factors, and sport-related factors. Decisions regarding return to play vary according to 5 specific characteristics of each clinical case. These findings help establish areas of consensus and disagreement in the management of children with injuries and safe return to physical activity.

  20. Modeling for the management of peak loads on a radiology image management network

    International Nuclear Information System (INIS)

    Dwyer, S.J.; Cox, G.G.; Templeton, A.W.; Cook, L.T.; Anderson, W.H.; Hensley, K.S.

    1987-01-01

    The design of a radiology image management network for a radiology department can now be assisted by a queueing model. The queueing model requires that the designers specify the following parameters: the number of tasks to be accomplished (acquisition of image data, transmission of data, archiving of data, displaying and manipulation of data, and generation of hard copies); the average times to complete each task; the patient scheduled arrival times; and the number/type of computer nodes interfaced to the network (acquisition nodes, interactive diagnostic display stations, archiving nodes, hard copy nodes, and gateways to hospital systems). The outcomes from the queuering model include mean throughput data rates and identified bottlenecks, and peak throughput data rates and identified bottlenecks. This exhibit presents the queueing model and illustrates its use in managing peak loads on an image management network