WorldWideScience

Sample records for queuing

  1. Queuing Theory and Reference Transactions.

    Science.gov (United States)

    Terbille, Charles

    1995-01-01

    Examines the implications of applying the queuing theory to three different reference situations: (1) random patron arrivals; (2) random durations of transactions; and (3) use of two librarians. Tables and figures represent results from spreadsheet calculations of queues for each reference situation. (JMV)

  2. Automatic Queuing Model for Banking Applications

    Directory of Open Access Journals (Sweden)

    Dr. Ahmed S. A. AL-Jumaily

    2011-08-01

    Full Text Available Queuing is the process of moving customers in a specific sequence to a specific service according to the customer need. The term scheduling stands for the process of computing a schedule. This may be done by a queuing based scheduler. This paper focuses on the banks lines system, the different queuing algorithms that are used in banks to serve the customers, and the average waiting time. The aim of this paper is to build automatic queuing system for organizing the banks queuing system that can analyses the queue status and take decision which customer to serve. The new queuing architecture model can switch between different scheduling algorithms according to the testing results and the factor of the average waiting time. The main innovation of this work concerns the modeling of the average waiting time is taken into processing, in addition with the process of switching to the scheduling algorithm that gives the best average waiting time.

  3. Distributed Queuing in Dynamic Networks

    Directory of Open Access Journals (Sweden)

    Gokarna Sharma

    2013-10-01

    Full Text Available We consider the problem of forming a distributed queue in the adversarial dynamic network model of Kuhn, Lynch, and Oshman (STOC 2010 in which the network topology changes from round to round but the network stays connected. This is a synchronous model in which network nodes are assumed to be fixed, the communication links for each round are chosen by an adversary, and nodes do not know who their neighbors are for the current round before they broadcast their messages. Queue requests may arrive over rounds at arbitrary nodes and the goal is to eventually enqueue them in a distributed queue. We present two algorithms that give a total distributed ordering of queue requests in this model. We measure the performance of our algorithms through round complexity, which is the total number of rounds needed to solve the distributed queuing problem. We show that in 1-interval connected graphs, where the communication links change arbitrarily between every round, it is possible to solve the distributed queueing problem in O(nk rounds using O(log n size messages, where n is the number of nodes in the network and k 0 is the concurrency level parameter that captures the minimum number of active queue requests in the system in any round. These results hold in any arbitrary (sequential, one-shot concurrent, or dynamic arrival of k queue requests in the system. Moreover, our algorithms ensure correctness in the sense that each queue request is eventually enqueued in the distributed queue after it is issued and each queue request is enqueued exactly once. We also provide an impossibility result for this distributed queuing problem in this model. To the best of our knowledge, these are the first solutions to the distributed queuing problem in adversarial dynamic networks.

  4. QUALITY OF SERVICE AND RELIABILITY WITH WEIGHTED FAIR QUEUING AND CUSTOM QUEUING IN OPTICAL COMMUNICATION

    Directory of Open Access Journals (Sweden)

    JITENDRA SAXENA

    2011-09-01

    Full Text Available Quality of service is a very important and vital issue for maintaining optical network with respect signal quality, jitter, and delay. Queuing theory is an important parameter to maintain triple play quality of service i.e video, voice and data. The network consists of different type of quality of service model client/ server model and a video client to client model. Video traffic is queued and prioritized in the firewall by using weighted fast queuing.

  5. The Application of Phase Type Distributions for Modelling Queuing Systems

    Directory of Open Access Journals (Sweden)

    EIMUTIS VALAKEVICIUS

    2007-12-01

    Full Text Available Queuing models are important tools for studying the performance of complex systems, but despite the substantial queuing theory literature, it is often necessary to use approximations in the case the system is nonmarkovian. Phase type distribution is by now indispensable tool in creation of queuing system models. The purpose of this paper is to suggest a method and software for evaluating queuing approximations. A numerical queuing model with priorities is used to explore the behaviour of exponential phase-type approximation of service-time distribution. The performance of queuing systems described in the event language is used for generating the set of states and transition matrix between them. Two examples of numerical models are presented – a queuing system model with priorities and a queuing system model with quality control.

  6. APPLICATION OF QUEUING THEORY TO INFORMATION SYSTEMS DESIGN.

    Science.gov (United States)

    information systems . A scheme of classifying queuing models and queuing literature was developed, and was used to classify most of the known priority...Finally, procedures for the application of the queuing model to structuring of information systems were outlined. (Author)

  7. Analysis of effectiveness of possible queuing models at gas stations using the large-scale queuing theory

    Directory of Open Access Journals (Sweden)

    Slaviša M. Ilić

    2011-10-01

    Full Text Available This paper analyzes the effectiveness of possible models for queuing at gas stations, using a mathematical model of the large-scale queuing theory. Based on actual data collected and the statistical analysis of the expected intensity of vehicle arrivals and queuing at gas stations, the mathematical modeling of the real process of queuing was carried out and certain parameters quantified, in terms of perception of the weaknesses of the existing models and the possible benefits of an automated queuing model.

  8. Virtual queuing at airport security lanes

    NARCIS (Netherlands)

    Lange, de R.; Samoilovich, I.; Rhee, van der B.

    2013-01-01

    Airports continuously seek opportunities to reduce the security costs without negatively affecting passenger satisfaction. In this paper, we investigate the possibilities of implementing virtual queuing at airport security lanes, by offering some passengers a time window during which they can arrive

  9. Improving queuing service at McDonald's

    Science.gov (United States)

    Koh, Hock Lye; Teh, Su Yean; Wong, Chin Keat; Lim, Hooi Kie; Migin, Melissa W.

    2014-07-01

    Fast food restaurants are popular among price-sensitive youths and working adults who value the conducive environment and convenient services. McDonald's chains of restaurants promote their sales during lunch hours by offering package meals which are perceived to be inexpensive. These promotional lunch meals attract good response, resulting in occasional long queues and inconvenient waiting times. A study is conducted to monitor the distribution of waiting time, queue length, customer arrival and departure patterns at a McDonald's restaurant located in Kuala Lumpur. A customer survey is conducted to gauge customers' satisfaction regarding waiting time and queue length. An android app named Que is developed to perform onsite queuing analysis and report key performance indices. The queuing theory in Que is based upon the concept of Poisson distribution. In this paper, Que is utilized to perform queuing analysis at this McDonald's restaurant with the aim of improving customer service, with particular reference to reducing queuing time and shortening queue length. Some results will be presented.

  10. Queuing Rule of Thumb based on M/M/s Queuing Theory with Applications in Construction Management

    Directory of Open Access Journals (Sweden)

    Teknomo K.

    2012-01-01

    Full Text Available The current trend of queuing theory development is toward more precision which requires higher mathematical manipulation. In this paper, we attempted to reverve the current trend toward simplification of queuing formulas such that it can be used in more practical purposes, especially in construction industry. Through numerical examples of two case studies on concreting and earth moving, how to model the construction activities as queuing systems is illustrated systematically. Through the numerical examples, it is shown that when the customer cost is much lower than the server cost, queuing system can be simplified only to incorporate the constraint equation. The queueing constraint equation is suggested to be used as queuing rule of thumb. The proposed rule of thumb is rather conservative in term of queuing performance compared to the standard stochastic queuing formula because it is assumed that all the customers arrive at once in the beginning of the service.

  11. A COMBINED LOW LATENCY AND WEIGHTED FAIR QUEUING BASED SCHEDULING OF AN INPUT-QUEUED SWITCH

    Directory of Open Access Journals (Sweden)

    D. Raghupathikumar

    2014-01-01

    Full Text Available Input queuing has become dominant and popular building blocks for high speed crossbar switches with many ports and fast line rates because they require minimum speed-up of memory bandwidth. Input Queued switches with finite Virtual Output Queues guarantees QoS performance in terms of throughput and average delay. A switch performs two functions Queuing and Scheduling. Queue Management algorithm manages the size of the queues and drops packets when necessary or appropriate. Scheduling algorithms determine next packet to transfer and solves conflicts with the switching fabric. Fairness and Starvation are another two properties of IQ switches and it is analyzed in finite VOQ in this works. Fairness performs fair allocation of bandwidth among flows and prevents flows from misbehaving flows. Starvation of VOQ prevents serving High priority queue. The motivation behind this study is to schedule the HoL packets queued in finite VOQs by Framing with Low Latency Queuing (LLQ and Weighted Fair Queueing (WFQ. This queueing technique of VOQ is measured in terms of throughput and average delay by fair allocation of bandwidth with WFQ and Starvation-free queue with LLQ.

  12. Human Factors of Queuing: A Library Circulation Model.

    Science.gov (United States)

    Mansfield, Jerry W.

    1981-01-01

    Classical queuing theories and their accompanying service facilities totally disregard the human factors in the name of efficiency. As library managers we need to be more responsive to human needs in the design of service points and make every effort to minimize queuing and queue frustration. Five references are listed. (Author/RAA)

  13. Mathematical methods in the theory of queuing

    CERN Document Server

    Khinchin, A Y; Quenouille, M H

    2013-01-01

    Written by a prominent Russian mathematician, this concise monograph examines aspects of queuing theory as an application of probability. The three-part treatment begins with a study of the stream of incoming demands (or ""calls,"" in the author's terminology). Subsequent sections explore systems with losses and systems allowing delay. Prerequisites include a familiarity with the theory of probability and mathematical analysis. A. Y. Khinchin made significant contributions to probability theory, statistical physics, and several other fields. His elegant, groundbreaking work will prove of subs

  14. Dynamic queuing transmission model for dynamic network loading

    DEFF Research Database (Denmark)

    Raovic, Nevena; Nielsen, Otto Anker; Prato, Carlo Giacomo

    2017-01-01

    This paper presents a new macroscopic multi-class dynamic network loading model called Dynamic Queuing Transmission Model (DQTM). The model utilizes ‘good’ properties of the Dynamic Queuing Model (DQM) and the Link Transmission Model (LTM) by offering a DQM consistent with the kinematic wave theory...... and allowing for the representation of multiple vehicle classes, queue spillbacks and shock waves. The model assumes that a link is split into a moving part plus a queuing part, and p that traffic dynamics are given by a triangular fundamental diagram. A case-study is investigated and the DQTM is compared...

  15. Queuing theory and telecommunications networks and applications

    CERN Document Server

    Giambene, Giovanni

    2014-01-01

    This book provides a basic description of current networking technologies and protocols as well as important tools for network performance analysis based on queuing theory. The second edition adds selected contents in the first part of the book for what concerns: (i) the token bucket regulator and traffic shaping issues; (ii) the TCP protocol congestion control that has a significant part in current networking; (iii) basic satellite networking issues; (iv) adding details on QoS support in IP networks. The book is organized so that networking technologies and protocols (Part I) are first and are then followed by theory and exercises with applications to the different technologies and protocols (Part II). This book is intended as a textbook for master level courses in networking and telecommunications sectors.

  16. Queuing theory models for computer networks

    Science.gov (United States)

    Galant, David C.

    1989-01-01

    A set of simple queuing theory models which can model the average response of a network of computers to a given traffic load has been implemented using a spreadsheet. The impact of variations in traffic patterns and intensities, channel capacities, and message protocols can be assessed using them because of the lack of fine detail in the network traffic rates, traffic patterns, and the hardware used to implement the networks. A sample use of the models applied to a realistic problem is included in appendix A. Appendix B provides a glossary of terms used in this paper. This Ames Research Center computer communication network is an evolving network of local area networks (LANs) connected via gateways and high-speed backbone communication channels. Intelligent planning of expansion and improvement requires understanding the behavior of the individual LANs as well as the collection of networks as a whole.

  17. Application of queuing theory in banking services

    Directory of Open Access Journals (Sweden)

    Vitor Costa de Lima

    2016-03-01

    Full Text Available Bearing in mind the intense competition in the current economy and the increasing necessity of having more customers and keeping them loyal, this paper aims to apply the well known Queuing Theory in a bank agency to identify improvement opportunities in customer waiting time, from the assumption that the analyzed lines follow the Poisson’s distribution. This assumption results from the comparison between such distribution to the customers' arrival data in all analyzed lines. It was also found that there are queues with seasonality in demand, while others showed a regular demand. From the study performed, improvements in the management of this bank agency may be made, for example, the reallocation of staff in certain periods for functions with higher demand. It was concluded, therefore, that the application of the theory is feasible and can help to increase the competitive advantages of the agency.

  18. A New CAC Method Using Queuing Theory

    Directory of Open Access Journals (Sweden)

    P. Kvackaj

    2008-12-01

    Full Text Available The CAC (Connection Admission Control method plays an important role in the ATM (Asynchronous Transfer Mode network environment. The CAC is the first step in the prevention of congested states in the network topology, and conducts to the optimal network resources utilization. The paper is aimed to propose an enhancement for a convolution method that is one of the statistical CAC methods used in ATM. The convolution method uses a buffer-less assumption in the estimation of the cell loss. Using formulas for the G/M/1 queuing system, the cell loss can be estimated as the buffer overflow probability. In this paper, the proposed CAC method is compared with other three statistical CAC methods, and conclusions regarding the exploitation of the CAC method are presented.

  19. Modelling traffic congestion using queuing networks

    Indian Academy of Sciences (India)

    Tushar Raheja

    2010-08-01

    Traffic studies have been carried out predominantly using simulation models which are both time and capital intensive. In this paper, an analytical model of uninterrupted single-lane traffic is proposed using queuing analysis. Well-known Traffic Flow-Density diagrams are obtained using simple Jackson queuing network analysis. Such simple analytical models can be used to capture the effect of nonhomogenous traffic.

  20. Price Dispersion and Short Run Equilibrium in a Queuing Model

    OpenAIRE

    Michael Sattinger

    2003-01-01

    Price dispersion is analyzed in the context of a queuing market where customers enter queues to acquire a good or service and may experience delays. With menu costs, price dispersion arises and can persist in the medium and long run. The queuing market rations goods in the same way whether firm prices are optimal or not. Price dispersion reduces the rate at which customers get the good and reduces customer welfare.

  1. Limit Theorems For Closed Queuing Networks With Excess Of Servers

    OpenAIRE

    Tsitsiashvili, G.

    2013-01-01

    In this paper limit theorems for closed queuing networks with excess of servers are formulated and proved. First theorem is a variant of the central limit theorem and is proved using classical results of V.I. Romanovskiy for discrete Markov chains. Second theorem considers a convergence to chi square distribution. These theorems are mainly based on an assumption of servers excess in queuing nodes.

  2. Weighted Priority Queuing: A New Scheduling Strategy for Web Services

    Directory of Open Access Journals (Sweden)

    Randa. Hammami

    2017-02-01

    Full Text Available Web services are considered as one of the best and most widespread solution for handling the interoperability problem and the challenge of integration. The proliferation of Web services over the Internet becomes more and more significant. They are henceforth playing an important role in several fields such as ehealth, e-commerce and e-learning. Thus, one important question arises: how to manage Web services more efficiently? It is a key problem to the Web services based- applications at present especially that the need to enhance the Quality of Services (QoS is constantly growing: the better the QoS are, the more the users are satisfied. This has spurred the study of scheduling algorithms for providing QoS guarantees. In this paper we put the light on the Web services requests scheduling strategies on the server side. In fact, we present a brief overview and a comparative evaluation of three queuing scheduling disciplines for Web services, which are: First in First out (FIFO, Priority Queuing (PQ and Weighted Fair Queuing (WFQ. Then, we put forward a new scheduling strategy based on two wellknown strategies namely: Priority Queuing and Weighted Fair Queuing. The experimental results highlight the merits and shortcomings of each scheduling discipline in addition to its performance in terms of: execution time, communication time and response time

  3. Queuing Network Analysis on Hybrid Flow Shop Scheduling

    Directory of Open Access Journals (Sweden)

    Fuqing Zhao

    2012-11-01

    Full Text Available In this study, we consider a queuing model extension for a production system composed of several parallel machines and the same number of transporters. To obtain the minimum waiting time of the jobs in the queue, we present an exact solution for the proposed queuing model. The solution integrates M/M/C system with M/M/1 system. We obtain explicit expressions for its steady-state behavior under M/M/C and M/M/1 assumptions. Further, in order to illustrate the usefulness of the proposed methods, numerical examples are solved. On the basis of the results of these examples, some important conclusions are drawn.

  4. A tutorial on queuing and trunking with applications to communications

    CERN Document Server

    Tranter, William H

    2012-01-01

    The motivation for developing this synthesis lecture was to provide a tutorial on queuing and trunking, with extensions to networks of queues, suitable for supplementing courses in communications, stochastic processes, and networking. An essential component of this lecture is MATLAB-based demonstrations and exercises, which can be easily modified to enable the student to observe and evaluate the impact of changing parameters, arrival and departure statistics, queuing disciplines, the number of servers, and other important aspects of the underlying system model. Much of the work in this lecture

  5. Application of queuing theory in production-inventory optimization

    Science.gov (United States)

    Rashid, Reza; Hoseini, Seyed Farzad; Gholamian, M. R.; Feizabadi, Mohammad

    2015-07-01

    This paper presents a mathematical model for an inventory control system in which customers' demands and suppliers' service time are considered as stochastic parameters. The proposed problem is solved through queuing theory for a single item. In this case, transitional probabilities are calculated in steady state. Afterward, the model is extended to the case of multi-item inventory systems. Then, to deal with the complexity of this problem, a new heuristic algorithm is developed. Finally, the presented bi-level inventory-queuing model is implemented as a case study in Electroestil Company.

  6. Efficient heuristics for simulating rare events in queuing networks

    NARCIS (Netherlands)

    Zaburnenko, T.S.

    2008-01-01

    In this thesis we propose state-dependent importance sampling heuristics to estimate the probability of population overflow in queuing networks. These heuristics capture state-dependence along the boundaries (when one or more queues are almost empty) which is crucial for the asymptotic efficiency of

  7. An application of queuing theory to waterfowl migration

    Science.gov (United States)

    Sojda, Richard S.; Cornely, John E.; Fredrickson, Leigh H.; Rizzoli, A.E.; Jakeman, A.J.

    2002-01-01

    There has always been great interest in the migration of waterfowl and other birds. We have applied queuing theory to modelling waterfowl migration, beginning with a prototype system for the Rocky Mountain Population of trumpeter swans (Cygnus buccinator) in Western North America. The queuing model can be classified as a D/BB/28 system, and we describe the input sources, service mechanism, and network configuration of queues and servers. The intrinsic nature of queuing theory is to represent the spatial and temporal characteristics of entities and how they move, are placed in queues, and are serviced. The service mechanism in our system is an algorithm representing how swans move through the flyway based on seasonal life cycle events. The system uses an observed number of swans at each of 27 areas for a breeding season as input and simulates their distribution through four seasonal steps. The result is a simulated distribution of birds for the subsequent year's breeding season. The model was built as a multiagent system with one agent handling movement algorithms, with one facilitating user interface, and with one to seven agents representing specific geographic areas for which swan management interventions can be implemented. The many parallels in queuing model servers and service mechanisms with waterfowl management areas and annual life cycle events made the transfer of the theory to practical application straightforward.

  8. Queuing Theory: An Alternative Approach to Educational Research.

    Science.gov (United States)

    Huyvaert, Sarah H.

    Queuing theory is examined in this paper in order to determine if the theory could be applied in educational settings. It is defined as a form of operations research that uses mathematical formulas and/or computer simulation to study wait and congestion in a system and, through the study of these visible phenomena, to discover malfunctions within…

  9. A single-server Markovian queuing system with discouraged arrivals and retention of reneged customers

    Directory of Open Access Journals (Sweden)

    Kumar Rakesh

    2014-01-01

    Full Text Available Customer impatience has a very negative impact on the queuing system under investigation. If we talk from business point of view, the firms lose their potential customers due to customer impatience, which affects their business as a whole. If the firms employ certain customer retention strategies, then there are chances that a certain fraction of impatient customers can be retained in the queuing system. A reneged customer may be convinced to stay in the queuing system for his further service with some probability, say q and he may abandon the queue without receiving the service with a probability p(=1− q. A finite waiting space Markovian single-server queuing model with discouraged arrivals, reneging and retention of reneged customers is studied. The steady state solution of the model is derived iteratively. The measures of effectiveness of the queuing model are also obtained. Some important queuing models are derived as special cases of this model.

  10. Time-varying priority queuing models for human dynamics.

    Science.gov (United States)

    Jo, Hang-Hyun; Pan, Raj Kumar; Kaski, Kimmo

    2012-06-01

    Queuing models provide insight into the temporal inhomogeneity of human dynamics, characterized by the broad distribution of waiting times of individuals performing tasks. We theoretically study the queuing model of an agent trying to execute a task of interest, the priority of which may vary with time due to the agent's "state of mind." However, its execution is disrupted by other tasks of random priorities. By considering the priority of the task of interest either decreasing or increasing algebraically in time, we analytically obtain and numerically confirm the bimodal and unimodal waiting time distributions with power-law decaying tails, respectively. These results are also compared to the updating time distribution of papers in arXiv.org and the processing time distribution of papers in Physical Review journals. Our analysis helps to understand human task execution in a more realistic scenario.

  11. Time-Varying Priority Queuing Models for Human Dynamics

    CERN Document Server

    Jo, Hang-Hyun; Kaski, Kimmo

    2011-01-01

    Queuing models provide insight into the temporal inhomogeneity of human dynamics, characterized by the broad distribution of waiting times of individuals performing tasks. We study the queuing model of an agent trying to execute a task of interest, the priority of which may vary with time due to the agent's "state of mind." However, its execution can be disrupted by other tasks of random priorities. By considering the priority of the task of interest either decreasing or increasing algebraically in time, we analytically obtain and numerically confirm the bimodal and unimodal waiting time distributions with power-law decaying tails, respectively. These results are also compared to the updating time distribution of papers in the arXiv and the processing time distribution of papers in Physical Review journals. Our analysis helps to understand the human task execution behavior in a more realistic scenario.

  12. STF: PROVIDE RATE GUARANTEES IN INPUT-QUEUED SWITCH

    Institute of Scientific and Technical Information of China (English)

    Wang Wenjie; Wei Gang

    2002-01-01

    A QoS-aware input-queued scheduling algorithm, called Smallest Timestamp First (STF), is proposed, which is improved upon iSLIP and can allocate bandwidth among inputs sharing a common output based on their reservation by assigning suitable finishing timestamps to contending cells. STF can also provide isolation between flows that share a common output link.Misbehaving flows will be restricted to guarantee the behaving flows' bandwidth. Simulatious prove the feasibility of our algorithm.

  13. Finite Block-Length Achievable Rates for Queuing Timing Channels

    OpenAIRE

    2011-01-01

    The exponential server timing channel is known to be the simplest, and in some sense canonical, queuing timing channel. The capacity of this infinite-memory channel is known. Here, we discuss practical finite-length restrictions on the codewords and attempt to understand the amount of maximal rate that can be achieved for a target error probability. By using Markov chain analysis, we prove a lower bound on the maximal channel coding rate achievable at blocklength $n$ and error probability $...

  14. Application of queuing model in Dubai's busiest megaplex

    Science.gov (United States)

    Bhagchandani, Maneesha; Bajpai, Priti

    2013-09-01

    This paper provides a study and analysis of the extremely busy booking counters at the Megaplex in Dubai using the queuing model and simulation. Dubai is an emirate in UAE with a multicultural population. Majority of the population in Dubai is foreign born. Cinema is one of the major forms of entertainment. There are more than 13 megaplexes each with a number of screens ranging from 3 to 22. They screen movies in English, Arabic, Hindi and other languages. It has been observed that during the weekends megaplexes attract a large number of crowd resulting in long queues at the booking counters. One of the busiest megaplex was selected for the study. Queuing theory satisfies the model when tested in real time situation. The concepts of arrival rate, service rate, utilization rate, waiting time in the system, average number of people in the queue, using Little's Theorem and M/M/s queuing model along with simulation software have been used to suggest an empirical solution. The aim of the paper is twofold-To assess the present situation at the Megaplex and give recommendations to optimize the use of booking counters.

  15. Queuing theory accurately models the need for critical care resources.

    Science.gov (United States)

    McManus, Michael L; Long, Michael C; Cooper, Abbot; Litvak, Eugene

    2004-05-01

    Allocation of scarce resources presents an increasing challenge to hospital administrators and health policy makers. Intensive care units can present bottlenecks within busy hospitals, but their expansion is costly and difficult to gauge. Although mathematical tools have been suggested for determining the proper number of intensive care beds necessary to serve a given demand, the performance of such models has not been prospectively evaluated over significant periods. The authors prospectively collected 2 years' admission, discharge, and turn-away data in a busy, urban intensive care unit. Using queuing theory, they then constructed a mathematical model of patient flow, compared predictions from the model to observed performance of the unit, and explored the sensitivity of the model to changes in unit size. The queuing model proved to be very accurate, with predicted admission turn-away rates correlating highly with those actually observed (correlation coefficient = 0.89). The model was useful in predicting both monthly responsiveness to changing demand (mean monthly difference between observed and predicted values, 0.4+/-2.3%; range, 0-13%) and the overall 2-yr turn-away rate for the unit (21%vs. 22%). Both in practice and in simulation, turn-away rates increased exponentially when utilization exceeded 80-85%. Sensitivity analysis using the model revealed rapid and severe degradation of system performance with even the small changes in bed availability that might result from sudden staffing shortages or admission of patients with very long stays. The stochastic nature of patient flow may falsely lead health planners to underestimate resource needs in busy intensive care units. Although the nature of arrivals for intensive care deserves further study, when demand is random, queuing theory provides an accurate means of determining the appropriate supply of beds.

  16. Reducing external speedup requirements for input-queued crossbars

    DEFF Research Database (Denmark)

    Berger, Michael Stubert

    2005-01-01

    This paper presents a modified architecture for an input queued switch that reduces external speedup. Maximal size scheduling algorithms for input-buffered crossbars requires a speedup between port card and switch card. The speedup is typically in the range of 2, to compensate for the scheduler...... performance degradation. This implies, that the required bandwidth between port card and switch card is 2 times the actual port speed, adding to cost and complexity. To reduce this bandwidth, a modified architecture is proposed that introduces a small amount of input and output memory on the switch card chip...

  17. Autocorrelation in queuing network-type production systems - revisited

    DEFF Research Database (Denmark)

    Nielsen, Erland Hejn

    2007-01-01

    In managing production systems, a strong emphasis is placed on the reduction of variance in specific transformation processes (e.g. for quality control purposes) and on controlling the level of variability in general, as for instance with the Bullwhip effect. However, the possible disturbing......, either production managers are missing important aspects in production planning, or the 'realistic' autocorrelation patterns inherent in actual production setups are not like those considered in the literature. In this paper, relevant and 'realistic' types of autocorrelation schemes are characterised...... and their levels discussed. The paper puts previous works on the impact of autocorrelation in queuing networks in perspective for production systems....

  18. Queuing Time Prediction Using WiFi Positioning Data in an Indoor Scenario.

    Science.gov (United States)

    Shu, Hua; Song, Ci; Pei, Tao; Xu, Lianming; Ou, Yang; Zhang, Libin; Li, Tao

    2016-11-22

    Queuing is common in urban public places. Automatically monitoring and predicting queuing time can not only help individuals to reduce their wait time and alleviate anxiety but also help managers to allocate resources more efficiently and enhance their ability to address emergencies. This paper proposes a novel method to estimate and predict queuing time in indoor environments based on WiFi positioning data. First, we use a series of parameters to identify the trajectories that can be used as representatives of queuing time. Next, we divide the day into equal time slices and estimate individuals' average queuing time during specific time slices. Finally, we build a nonstandard autoregressive (NAR) model trained using the previous day's WiFi estimation results and actual queuing time to predict the queuing time in the upcoming time slice. A case study comparing two other time series analysis models shows that the NAR model has better precision. Random topological errors caused by the drift phenomenon of WiFi positioning technology (locations determined by a WiFi positioning system may drift accidently) and systematic topological errors caused by the positioning system are the main factors that affect the estimation precision. Therefore, we optimize the deployment strategy during the positioning system deployment phase and propose a drift ratio parameter pertaining to the trajectory screening phase to alleviate the impact of topological errors and improve estimates. The WiFi positioning data from an eight-day case study conducted at the T3-C entrance of Beijing Capital International Airport show that the mean absolute estimation error is 147 s, which is approximately 26.92% of the actual queuing time. For predictions using the NAR model, the proportion is approximately 27.49%. The theoretical predictions and the empirical case study indicate that the NAR model is an effective method to estimate and predict queuing time in indoor public areas.

  19. Queuing model of a traffic bottleneck with bimodal arrival rate

    Science.gov (United States)

    Woelki, Marko

    2016-06-01

    This paper revisits the problem of tuning the density in a traffic bottleneck by reduction of the arrival rate when the queue length exceeds a certain threshold, studied recently for variants of totally asymmetric simple exclusion process (TASEP) and Burgers equation. In the present approach, a simple finite queuing system is considered and its contrasting “phase diagram” is derived. One can observe one jammed region, one low-density region and one region where the queue length is equilibrated around the threshold. Despite the simplicity of the model the physics is in accordance with the previous approach: The density is tuned at the threshold if the exit rate lies in between the two arrival rates.

  20. AN EFFICIENT SCHEDULING ALGORITHM FOR INPUT-QUEUED SWITCHES

    Institute of Scientific and Technical Information of China (English)

    Hu Qingsheng; Sun Yuan; Han Jiangtao

    2007-01-01

    This letter presents an efficient scheduling algorithm DTRR (Dual-Threshold Round Robin) for input-queued switches. In DTRR, a new matched input and output by round robin in a cell time will be locked by two self-adaptive thresholds whenever the queue length or the wait-time of the head cell in the corresponding Virtual Output Queue (VOQ) exceeds the thresholds. The locked input and output will be matched directly in the succeeding cell time until they are unlocked.By employing queue length and wait-time thresholds which are updated every cell time simultaneously, DTRR achieves a good tradeoff between the performance and hardware complexity. Simulation results indicate that the delay performance of DTRR is competitive compared to other typical scheduling algorithms under various traffic patterns especially under diagonal traffic.

  1. Application of queuing theory in inventory systems with substitution flexibility

    Science.gov (United States)

    Seyedhoseini, S. M.; Rashid, Reza; Kamalpour, Iman; Zangeneh, Erfan

    2015-01-01

    Considering the competition in today's business environment, tactical planning of a supply chain becomes more complex than before. In many multi-product inventory systems, substitution flexibility can improve profits. This paper aims to prepare a comprehensive substitution inventory model, where an inventory system with two substitute products with ignorable lead time has been considered, and effects of simultaneous ordering have been examined. In this paper, demands of customers for both of the products have been regarded as stochastic parameters, and queuing theory has been used to construct a mathematical model. The model has been coded by C++, and it has been analyzed due to a real example, where the results indicate efficiency of proposed model.

  2. Design and Implementation of an M/M/1 Queuing Model Algorithm ...

    African Journals Online (AJOL)

    simulation using the Queuing Model Simulator (QMS), simulation software which computes the mean ... electrical interference, base level fluctuations, and absence of numeric readouts and alarms. In ..... Mathematical Statistics 24 (3). [4].

  3. Modeling and simulation of M/M/c queuing pharmacy system with adjustable parameters

    Science.gov (United States)

    Rashida, A. R.; Fadzli, Mohammad; Ibrahim, Safwati; Goh, Siti Rohana

    2016-02-01

    This paper studies a discrete event simulation (DES) as a computer based modelling that imitates a real system of pharmacy unit. M/M/c queuing theo is used to model and analyse the characteristic of queuing system at the pharmacy unit of Hospital Tuanku Fauziah, Kangar in Perlis, Malaysia. The input of this model is based on statistical data collected for 20 working days in June 2014. Currently, patient waiting time of pharmacy unit is more than 15 minutes. The actual operation of the pharmacy unit is a mixed queuing server with M/M/2 queuing model where the pharmacist is referred as the server parameters. DES approach and ProModel simulation software is used to simulate the queuing model and to propose the improvement for queuing system at this pharmacy system. Waiting time for each server is analysed and found out that Counter 3 and 4 has the highest waiting time which is 16.98 and 16.73 minutes. Three scenarios; M/M/3, M/M/4 and M/M/5 are simulated and waiting time for actual queuing model and experimental queuing model are compared. The simulation results show that by adding the server (pharmacist), it will reduce patient waiting time to a reasonable improvement. Almost 50% average patient waiting time is reduced when one pharmacist is added to the counter. However, it is not necessary to fully utilize all counters because eventhough M/M/4 and M/M/5 produced more reduction in patient waiting time, but it is ineffective since Counter 5 is rarely used.

  4. A CATASTROPHIC-CUM-RESTORATIVE QUEUING SYSTEM WITH CORRELATED BATCH ARRIVALS AND VARIABLE CAPACITY

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar

    2008-07-01

    Full Text Available In this paper, we study a catastrophic-cum-restorative queuing system with correlated batch arrivals and service in batches of variable sizes. We perform the transient analysis of the queuing model. We obtain the Laplace Transform of the probability generating function of system size. Finally, some particular cases of the model have been derived and discussed. Keywords: Queue length, Catastrophes, Correlated batch arrivals, Broadband services, Variable service capacity, and Restoration.

  5. CALCULATIONS OF PERFOMANCE PRODUCTIVITY OF ATC AS A QUEUING SYSTEM WITH FAILURES

    Directory of Open Access Journals (Sweden)

    I. N. Shestakov

    2014-01-01

    Full Text Available The article give reasons for possibility of the investigation of the ATC system as a queuing system with failures. The concept of the failure is explained through the extreme condition of an ATC Unit. Criteria of the system’s performance productivity within the theory of queuing are given. The results of the calculations of the system’s productivity are provided.

  6. Discrete Event Simulation Models for CT Examination Queuing in West China Hospital.

    Science.gov (United States)

    Luo, Li; Liu, Hangjiang; Liao, Huchang; Tang, Shijun; Shi, Yingkang; Guo, Huili

    2016-01-01

    In CT examination, the emergency patients (EPs) have highest priorities in the queuing system and thus the general patients (GPs) have to wait for a long time. This leads to a low degree of satisfaction of the whole patients. The aim of this study is to improve the patients' satisfaction by designing new queuing strategies for CT examination. We divide the EPs into urgent type and emergency type and then design two queuing strategies: one is that the urgent patients (UPs) wedge into the GPs' queue with fixed interval (fixed priority model) and the other is that the patients have dynamic priorities for queuing (dynamic priority model). Based on the data from Radiology Information Database (RID) of West China Hospital (WCH), we develop some discrete event simulation models for CT examination according to the designed strategies. We compare the performance of different strategies on the basis of the simulation results. The strategy that patients have dynamic priorities for queuing makes the waiting time of GPs decrease by 13 minutes and the degree of satisfaction increase by 40.6%. We design a more reasonable CT examination queuing strategy to decrease patients' waiting time and increase their satisfaction degrees.

  7. On queue-size scaling for input-queued switches

    Directory of Open Access Journals (Sweden)

    Devavrat Shah

    2016-11-01

    Full Text Available We study the optimal scaling of the expected total queue size in an n×n input-queued switch, as a function of the number of ports n and the load factor ρ, which has been conjectured to be Θ(n/(1−ρ (cf. [15]. In a recent work [16], the validity of this conjecture has been established for the regime where 1−ρ=O(1/n2. In this paper, we make further progress in the direction of this conjecture. We provide a new class of scheduling policies under which the expected total queue size scales as O(n1.5(1−ρ−1log(1/(1−ρ when 1−ρ=O(1/n. This is an improvement over the state of the art; for example, for ρ=1−1/n the best known bound was O(n3, while ours is O(n2.5logn.

  8. Sick of queuing? The Registration Service has the answer

    CERN Multimedia

    Antonella Del Rosso

    2015-01-01

    At the beginning of the year, CERN's Registration Service, in its fully renovated premises, launched a new initiative to save you time and to optimise the work of its staff.   One free-to-download application, two ticket printers and three screens: behind this simple-looking system sits an ingenious process (see the slideshow) that will enable you to avoid long waiting times at CERN's Registration Service. The Service delivers some 22 000 badges each year, reaching a peak of 700 per week, and is therefore one of the few places at CERN where queuing is the norm.  But that could all change thanks to Qminder, an app that allows users to monitor the waiting times in Building 55 from their smartphones. From today, you can take a virtual ticket using your device and see how long you will have to wait before your case is handled by the next available member of staff.  “The system can also provide statistics on waiting times in the various registration service...

  9. Fuzzy Optimization and Normal Simulation for Solving Fuzzy Web Queuing System Problems

    Directory of Open Access Journals (Sweden)

    Xidong Zheng

    2005-04-01

    Full Text Available In this paper, we use both fuzzy optimization and normal simulation methods to solve fuzzy web planning model problems, which are queuing system problems for designing web servers. We apply fuzzy probabilities to the queuing system models with customers arrival rate l and servers?service rate m, and then compute fuzzy system performance variables, including Utilization, Number (of requests in the System, Throughput, and Response Time. For the fuzzy optimization method, we apply two-step calculation, first use fuzzy calculation to get the maximum and minimum values of fuzzy steady state probabilities, and then we compute the fuzzy system performance variables. For the simulation method, we use one-step normal queuing theory to simulate the whole system performance and its variables. We deal with queuing systems with a single server and multiple servers?cases, and compare the results of these two cases, giving a mathematical explanation of the difference. Keywords: Fuzzy Optimization, Normal Simulation, Queuing Theory, Web Planning Model.

  10. Performance Analysis of Heterogeneous Data Centers in Cloud Computing Using a Complex Queuing Model

    Directory of Open Access Journals (Sweden)

    Wei-Hua Bai

    2015-01-01

    Full Text Available Performance evaluation of modern cloud data centers has attracted considerable research attention among both cloud providers and cloud customers. In this paper, we investigate the heterogeneity of modern data centers and the service process used in these heterogeneous data centers. Using queuing theory, we construct a complex queuing model composed of two concatenated queuing systems and present this as an analytical model for evaluating the performance of heterogeneous data centers. Based on this complex queuing model, we analyze the mean response time, the mean waiting time, and other important performance indicators. We also conduct simulation experiments to confirm the validity of the complex queuing model. We further conduct numerical experiments to demonstrate that the traffic intensity (or utilization of each execution server, as well as the configuration of server clusters, in a heterogeneous data center will impact the performance of the system. Our results indicate that our analytical model is effective in accurately estimating the performance of the heterogeneous data center.

  11. Study on Message Queuing Technology :Overview and a Case Study%消息队列技术研究:综述与一个实例

    Institute of Scientific and Technical Information of China (English)

    周世杰; 刘锦德; 秦志光

    2002-01-01

    The features and applications of message queuing technology are analyzed.After discussing the communication mode of message queuing,the differences among message queuing,remote procedure call and distributed transaction processing are clarified.Then,several kinds of application design patterns used in common application scenarios are carefully considered.Finally,how to design a real middileware system adopting message queuing technology is explained in detail.

  12. Variability of Green Time to Discharge a Specified Number of Queued Vehicles at a Signalized Intersection

    Directory of Open Access Journals (Sweden)

    Yi Zhao

    2017-01-01

    Full Text Available The aim of this paper is to study the headway distribution of queued vehicles (less than 16 vehicles at signalized intersections. Existing studies usually take the average statistics of headway at any queuing place. When different percentile points of statistical data are assigned to headway, the passing rate (the rate of all queued vehicles passing the stop line under the ideal signal timing scheme varies. When selecting the mean value, the passing rate of a queue of fewer than 16 vehicles is no more than 65%. When selecting 75% as the percentile, the passing rate is up to 94%. The queue length also decides the assigned percentile of headway to ensure the passing rate reaches a certain level. The value assignation of headway directly affects lane capacity and start-up loss time. This paper provides a new perspective on parameter calibration and will make the signal timing algorithm method more effective.

  13. Assessing the Queuing Process Using Data Envelopment Analysis: an Application in Health Centres.

    Science.gov (United States)

    Safdar, Komal A; Emrouznejad, Ali; Dey, Prasanta K

    2016-01-01

    Queuing is one of the very important criteria for assessing the performance and efficiency of any service industry, including healthcare. Data Envelopment Analysis (DEA) is one of the most widely-used techniques for performance measurement in healthcare. However, no queue management application has been reported in the health-related DEA literature. Most of the studies regarding patient flow systems had the objective of improving an already existing Appointment System. The current study presents a novel application of DEA for assessing the queuing process at an Outpatients' department of a large public hospital in a developing country where appointment systems do not exist. The main aim of the current study is to demonstrate the usefulness of DEA modelling in the evaluation of a queue system. The patient flow pathway considered for this study consists of two stages; consultation with a doctor and pharmacy. The DEA results indicated that waiting times and other related queuing variables included need considerable minimisation at both stages.

  14. A hybrid queuing strategy for network traffic on scale-free networks

    Science.gov (United States)

    Cai, Kai-Quan; Yu, Lu; Zhu, Yan-Bo

    2017-02-01

    In this paper, a hybrid queuing strategy (HQS) is proposed in traffic dynamics model on scale-free networks, where the delivery priority of packets in the queue is related to their distance to destination and the queue length of next jump. We compare the performance of the proposed HQS with that of the traditional first-in-first-out (FIFO) queuing strategy and the shortest-remaining-path-first (SRPF) queuing strategy proposed by Du et al. It is observed that the network traffic efficiency utilizing HQS with suitable value of parameter h can be further improved in the congestion state. Our work provides new insights for the understanding of the networked-traffic systems.

  15. Study on combat effectiveness of air defense missile weapon system based on queuing theory

    Science.gov (United States)

    Zhao, Z. Q.; Hao, J. X.; Li, L. J.

    2017-01-01

    Queuing Theory is a method to analyze the combat effectiveness of air defense missile weapon system. The model of service probability based on the queuing theory was constructed, and applied to analyzing the combat effectiveness of "Sidewinder" and "Tor-M1" air defense missile weapon system. Finally aimed at different targets densities, the combat effectiveness of different combat units of two types' defense missile weapon system is calculated. This method can be used to analyze the usefulness of air defense missile weapon system.

  16. Modeling of Spacing Distribution of Queuing Vehicles at Signalized Junctions Using Random-Matrix Theory

    Institute of Scientific and Technical Information of China (English)

    JIN Xuexiang; SU Yuelong; ZHANG Yi; WEI Zheng; LI Li

    2009-01-01

    The modeling of headway/spacing between two consecutive vehicles in a queue has many appli-cations in traffic flow theory and transport practice. Most known approaches have only studied vehicles on freeways. This paper presents a model for the spacing distribution of queuing vehicles at a signalized junc-tion based on random-matrix theory. The spacing distribution of a Gaussian symplectic ensemble (GSE) fits well with recently measured spacing distribution data. These results are also compared with measured spacing distribution observed for the car parking problem. Vehicle stationary queuing and vehicle parking have different spacing distributions due to different driving patterns.

  17. AN M/M/1/N FEEDBACK QUEUING SYSTEM WITH REVERSE BALKING

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar

    2015-06-01

    Full Text Available In this paper we develop an M/M/1/N feedback queuing system with reverse balking. Reverse balking is a type of customer behavior according to which an arriving customer joins a system with high probability if he encounters large system size and vice-versa. This behavior of a customer can be observed in many businesses such as investment. Feedback customer in queuing literature refers to a customer who is unsatisfied with incomplete, partial or unsatisfactory service. We derive the steady-state solution of the model and obtain some important measures of performance. Sensitivity analysis of the model is also performed with respect to the parameters involved.

  18. A stochastic analysis of goods allocation by queuing and the prevention of violence

    OpenAIRE

    2010-01-01

    When demand for a good exceeds its supply, queuing mechanisms are commonly used to allocate the good in question to citizens. However, very long queues result in excessive wait times and this can lead to violence. As such, the purpose of this paper is to analyze two stochastic models of goods allocation with queuing and the possibility of violence. In the first model, there is no capacity constraint. Using this model, we compute the long run delay per citizen in allocating the pertinent good....

  19. An application of a queuing model for sea states

    Science.gov (United States)

    Loffredo, L.; Monbaliu, J.; Anderson, C.

    2012-04-01

    Unimodal approaches in design practice have shown inconsistencies in terms of directionality and limitations for accurate sea states description. Spectral multimodality needs to be included in the description of the wave climate. It can provide information about the coexistence of different wave systems originating from different meteorological events, such as locally generated wind waves and swell systems from distant storms. A 20 years dataset (1989-2008) for a location on the North Sea (K13, 53.2°N 3.2°E) has been retrieved from the ECMWF ERA- Interim re-analysis data archive, providing a consistent and homogeneous dataset. The work focuses on the joint and conditional probability distributions of wind sea and swell systems. For marine operations and design applications, critical combinations of wave systems may exist. We define a critical sea state on the basis of a set of thresholds, which can be not necessarily extreme, the emphasis is given to the dangerous combination of different wave systems concerning certain operations (i.e. small vessels navigation, dredging). The distribution of non-operability windows is described by a point process model with random and independent events, whose occurrences and lengths can be described only probabilistically. These characteristics allow to treat the emerging patterns as a part of a queuing system. According to this theory, generally adopted for several applications including traffic flows and waiting lines, the input process describes the sequence of requests for a service and the service mechanism the length of time that these requests will occupy the facilities. For weather-driven processes at sea an alternating renewal process appears as a suitable model. It consists of a sequence of critical events (period of inoperability), each of random duration, separated by calms, also of random durations. Inoperability periods and calms are assumed independent. In this model it is not possible more than one critical

  20. On a two-server finite queuing system with ordered entry and deterministic arrivals

    NARCIS (Netherlands)

    Nawijn, W.M.

    1984-01-01

    Consider a two-server, ordered entry, queuing system with heterogeneous servers and finite waiting rooms in front of the servers. Service times are negative exponentially distributed. The arrival process is deterministic. A matrix solution for the steady state probabilities of the number of

  1. Efficient round-robin multicast scheduling for input-queued switches

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Yu, Hao; Ruepp, Sarah Renée

    2014-01-01

    problem. Using a separate queue for each output port at an input to reduce the HOL blocking, that is, the virtual output queuing discipline, increases the implementation complexity, which limits the scalability. Given the increasing link speed and network capacity, a low-complexity yet efficient multicast...

  2. MODELING QUEUING SYSTEM OF INTERACTION BETWEEN TERMINAL DEVICES AND SERVICES PROVIDERS IN THE BANK

    Directory of Open Access Journals (Sweden)

    Ivan A. Mnatsakanyan

    2014-01-01

    Full Text Available The article focuses on the development of mathematical models and tools to optimize the system of queuing at the bank. The article discusses the mathematical aspects that will achieve redistribution of transaction flow, reduce the time of the request in the queue, increase the bank’s profit and gain competitive advantage.

  3. Redesign of a university hospital preanesthesia evaluation clinic using a queuing theory approach.

    Science.gov (United States)

    Zonderland, Maartje E; Boer, Fredrik; Boucherie, Richard J; de Roode, Annemiek; van Kleef, Jack W

    2009-11-01

    Changes in patient length of stay (the duration of 1 clinic visit) as a result of the introduction of an electronic patient file system forced an anesthesia department to change its outpatient clinic organization. In this study, we sought to demonstrate how the involvement of essential employees combined with mathematical techniques to support the decision-making process resulted in a successful intervention. The setting is the preanesthesia evaluation clinic (PAC) of a university hospital, where patients consult several medical professionals, either by walk-in or appointment. Queuing theory was used to model the initial set-up of the clinic, and later to model possible alternative designs. With the queuing model, possible improvements in efficiency could be investigated. Inputs to the model were patient arrival rates and expected service times with clinic employees, collected from the clinic's logging system and by observation. The performance measures calculated with the model were patient length of stay and employee utilization rate. Supported by the model outcomes, a working group consisting of representatives of all clinic employees decided whether the initial design should be maintained or an intervention was needed. The queuing model predicted that 3 of the proposed alternatives would result in better performance. Key points in the intervention were the rescheduling of appointments and the reallocation of tasks. The intervention resulted in a shortening of the time the anesthesiologist needed to decide upon approving the patient for surgery. Patient arrivals increased sharply over 1 yr by more than 16%; however, patient length of stay at the clinic remained essentially unchanged. If the initial set-up of the clinic would have been maintained, the patient length of stay would have increased dramatically. Queuing theory provides robust methods to evaluate alternative designs for the organization of PACs. In this article, we show that queuing modeling is an

  4. Research on Performance Evaluation of Biological Database based on Layered Queuing Network Model under the Cloud Computing Environment

    OpenAIRE

    Zhengbin Luo; Dongmei Sun

    2013-01-01

    To evaluate the performance of biological database based on layered queuing network model and under cloud computing environment is a premise, as well as an important step for biological database optimization. Based on predecessors’ researches concerning computer software and hardware performance evaluation under cloud environment, the study has further constructed a model system to evaluate the performance of biological database based on layered queuing network model and under cloud environme...

  5. TWO-LEVEL HIERARCHICAL COORDINATION QUEUING METHOD FOR TELECOMMUNICATION NETWORK NODES

    Directory of Open Access Journals (Sweden)

    M. V. Semenyaka

    2014-07-01

    Full Text Available The paper presents hierarchical coordination queuing method. Within the proposed method a queuing problem has been reduced to optimization problem solving that was presented as two-level hierarchical structure. The required distribution of flows and bandwidth allocation was calculated at the first level independently for each macro-queue; at the second level solutions obtained on lower level for each queue were coordinated in order to prevent probable network link overload. The method of goal coordination has been determined for multilevel structure managing, which makes it possible to define the order for consideration of queue cooperation restrictions and calculation tasks distribution between levels of hierarchy. Decisions coordination was performed by the method of Lagrange multipliers. The study of method convergence has been carried out by analytical modeling.

  6. Application of dynamic priorities for controlling the characteristics of a queuing system

    Science.gov (United States)

    Polyanskiy, S. V.; Katsman, Yu Ya

    2017-01-01

    This paper considers the development and modification of an imitation model of a queuing system. The initial model uses the laws of control (discipline of expectation and service) with mixed priorities. The work investigates the model with three types of entities (absolute priority, relative priority and priority-free ones) in the regime of overload, i.e. a system with losses. Verification and validation of the created imitation model confirmed its adequateness and accuracy of received results. The application of dynamic priorities for changing the laws of model control substantially alters certain system characteristics. The creation of the model in MatLab Simulink environment with the use of SimEvents and Stateflow library modules allowed creating a fairly complex queuing system and obtain new interesting results.

  7. Denial of Service Attack: Analysis of Network Traffic Anormaly using Queuing Theory

    CERN Document Server

    Singh, Neetu; Chaudhuri, Pranay

    2010-01-01

    Denial-of-service (DOS) attacks increasingly gained reputation over the past few years. As the Internet becomes more ubiquitous, the threat of the denial-of-service attacks becomes more realistic and important for individuals, businesses, governmental organizations, and even countries. There is intensive need to detect an attack in progress as soon as possible. The efficiency of diagnosing the DOS attack using concepts of queuing theory and performance parameter of the system has been investigated in the present work, as the servers definitely have some mechanisms to store and process the requests. Utilizing this concept of queuing theory, the collection of data patterns were generated. With the performance parameter of the system, the analysis of the data pattern had been made to diagnose the network anomaly. Performance analysis and results show the accuracy of the proposed scheme in detecting anomalies.

  8. User Utility Oriented Queuing Model for Resource Allocation in Cloud Environment

    Directory of Open Access Journals (Sweden)

    Zhe Zhang

    2015-01-01

    Full Text Available Resource allocation is one of the most important research topics in servers. In the cloud environment, there are massive hardware resources of different kinds, and many kinds of services are usually run on virtual machines of the cloud server. In addition, cloud environment is commercialized, and economical factor should also be considered. In order to deal with commercialization and virtualization of cloud environment, we proposed a user utility oriented queuing model for task scheduling. Firstly, we modeled task scheduling in cloud environment as an M/M/1 queuing system. Secondly, we classified the utility into time utility and cost utility and built a linear programming model to maximize total utility for both of them. Finally, we proposed a utility oriented algorithm to maximize the total utility. Massive experiments validate the effectiveness of our proposed model.

  9. Characterizing and Managing Intrusion Detection System (IDS) Alerts with Multi-Server/Multi-Priority Queuing Theory

    Science.gov (United States)

    2014-12-26

    IDS called SNORT®. ( Roesch & Green, 2014) .......... 3 Figure 2. A basic queuing theory diagram calling out the six defining characteristics of a...particular format is from the popular open source IDS called SNORT®. ( Roesch & Green, 2014) The set of signatures within an IDS is called its rule-set...nicol/ece541/slides/queueing.pdf Roesch , M., & Green, C. (2014). SNORT Users Manual. Retrieved August 2014, from SNORT: http://manual.snort.org/ Saad

  10. APPLICATION OF THE SINGLE SERVER QUEUING SYSTEM ANALYSIS IN WOOD PRODUCTS INDUSTRY

    Directory of Open Access Journals (Sweden)

    Arif GÜRAY

    2001-01-01

    Full Text Available The aim of this study, simulated of the single server queuing system(CNC at the door-joinery facilities. We simulated the system both by hand and computer programming with SIMAN languages. From the obtained results, we aimed to provide some suggestions to the manager. Because, the ending of the study, simulation showed the real system in some hypothesis. As a result of simulated system will have long queues in future time.

  11. Nested Fork-Join Queuing Networks and Their Application to Mobility Airfield Operations Analysis.

    Science.gov (United States)

    1997-03-01

    Method. The accuracy of this approximation is similar to that of its single-class counterpart. A similar approach is used by Di Mascolo, Frein , Baynat and...et en Automatique , 1985. [9] Baccelli, F. and Z. Liu. "On the execution of parallel programs on multipro- cessor systems-a queuing theory approach...Le Chesnay, France: Institut National de Recherche en Informatique et en Automatique , 1986. [16] Baccelli, F., and others. "Acyclic fork-join

  12. Survey of Unicast and Multicast Scheduling Algorithms for High Speed Input Queued Switch with Crossbar

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The performance of ATM switches are mainly influenced by switching fabric and scheduling algorithms. Input buffered switches have the strong advantage of efficient crossbar usage. This paper presents an input-queued crossbar switches fabric supporting high speed switching, analyzes the scheduling algorithms for unicast trafficts and multicast traffic based on virtual output queueing (VOQ).Focusing on their performance issues, some typical schedulers are compared.

  13. Application of queuing theory to a fast food outfit: a study of blue meadows restaurant

    Directory of Open Access Journals (Sweden)

    Seigha Gumus

    2017-06-01

    Full Text Available The study evaluated the queuing system in Blue Meadows restaurant with a view to determining its operating characteristics and to improve customers’ satisfaction during waiting time using the lens of queuing theory. Data was obtained from a fast food restaurant in the University of Benin. The data collected was tested to show if it follows a Poisson and exponential distribution of arrival and service rate using chi square goodness of fit. A 95% confidence interval level was used to show the range of customers that come into the system at an hour time frame and the range of customers served at an hour time frame. Using the M/M/s model, the arrival rate, service rate, utilization rate, waiting time in the queue and the probability of customers likely balking from the restaurant was derived. The arrival rate (λ at Blue Meadows restaurant was about 40 customers per hour, while the service rate was about 22 customers per hour per server. The number of servers present in the system was two. The average number of customers in the system in an hour window was 40 customers with a utilization rate of 0.909. The paper concludes with a discussion on the benefits of performing queuing analysis to a restaurant.

  14. Analisa Perbandingan Quality of Service Voice Over IP dengan Pengujian Codec Menggunakan Algoritma Low Latency Queuing

    Directory of Open Access Journals (Sweden)

    Darmawan Darmawan

    2017-09-01

    Full Text Available Voice over IP (VoIP adalah solusi komunikasi suara yang murah karena menggunakan jaringan IP dibanding penggunaan telephone analog yang banyak memakan biaya. Dalam penerapannya, VoIP mengalami permasalahan karena menggunakan teknologi packet switching yang mana penggunaannya bersamaan dengan paket data sehingga timbul delay, jitter, dan packet loss.  Pada penelitian ini, algoritma Low Latency Queuing (LLQ diterapkan pada router cisco. Algoritma LLQ merupakan gabungan dari algoritma Priority Queuing (PQ dan Class Based Weight Fair Queuing (CBWFQ sehingga dapat memprioritaskan paket suara disamping paket data. Algoritma LLQ ini diujikan menggunakan codec GSM FR, G722, dan G711 A-law. Hasil pengujian didapatkan nilai parameter yang tidak jauh berbeda dan memenuhi standar ITU-T.G1010. Nilai delay rata - rata terendah yaitu ketika menggunakan codec G722 sebesar 20,019 ms tetapi G722 memiliki rata - rata jitter yang terbesar yaitu 0,986 ms.  Codec dengan jitter rata – rata terkecil adalah G711 A-law sebesar 0,838 ms. Packet loss untuk semua codec yang diujikan adalah 0%.  Throughput pada paket data terbesar saat menggunakan codec GSM FR yaitu 18,139 kbps. Codec yang direkomendasikan adalah G711 A-law karena lebih stabil dari segi jitter dan codec GSM FR cocok diimplementasikan pada jaringan yang memiliki bandwitdh kecil.

  15. 消息中间件的排队论模型研究%Study on the Queuing Model of the Message-Oriented Middleware

    Institute of Scientific and Technical Information of China (English)

    周世杰; 秦志光; 刘锦德

    2002-01-01

    The general concepts in message queuing and message-oriented middleware(MOM) are discussed. The essential elements and model of the queuing theory are analyzed in detail. Then, after puting forward and analyzing the basic formulas of the queuing theory, the applicable model for message queue middleware is probed into. Some important formulas used in the designing of the message queue middleware are also elucidated. Finally, a case of designing the message queue middleware adopting queuing model we put forward, which is used in the freeway toll system of ITS, is studied.

  16. Using Queuing Theory and Simulation Model to Optimize Hospital Pharmacy Performance

    Science.gov (United States)

    Bahadori, Mohammadkarim; Mohammadnejhad, Seyed Mohsen; Ravangard, Ramin; Teymourzadeh, Ehsan

    2014-01-01

    Background: Hospital pharmacy is responsible for controlling and monitoring the medication use process and ensures the timely access to safe, effective and economical use of drugs and medicines for patients and hospital staff. Objectives: This study aimed to optimize the management of studied outpatient pharmacy by developing suitable queuing theory and simulation technique. Patients and Methods: A descriptive-analytical study conducted in a military hospital in Iran, Tehran in 2013. A sample of 220 patients referred to the outpatient pharmacy of the hospital in two shifts, morning and evening, was selected to collect the necessary data to determine the arrival rate, service rate, and other data needed to calculate the patients flow and queuing network performance variables. After the initial analysis of collected data using the software SPSS 18, the pharmacy queuing network performance indicators were calculated for both shifts. Then, based on collected data and to provide appropriate solutions, the queuing system of current situation for both shifts was modeled and simulated using the software ARENA 12 and 4 scenarios were explored. Results: Results showed that the queue characteristics of the studied pharmacy during the situation analysis were very undesirable in both morning and evening shifts. The average numbers of patients in the pharmacy were 19.21 and 14.66 in the morning and evening, respectively. The average times spent in the system by clients were 39 minutes in the morning and 35 minutes in the evening. The system utilization in the morning and evening were, respectively, 25% and 21%. The simulation results showed that reducing the staff in the morning from 2 to 1 in the receiving prescriptions stage didn't change the queue performance indicators. Increasing one staff in filling prescription drugs could cause a decrease of 10 persons in the average queue length and 18 minutes and 14 seconds in the average waiting time. On the other hand, simulation

  17. Using queuing theory and simulation model to optimize hospital pharmacy performance.

    Science.gov (United States)

    Bahadori, Mohammadkarim; Mohammadnejhad, Seyed Mohsen; Ravangard, Ramin; Teymourzadeh, Ehsan

    2014-03-01

    Hospital pharmacy is responsible for controlling and monitoring the medication use process and ensures the timely access to safe, effective and economical use of drugs and medicines for patients and hospital staff. This study aimed to optimize the management of studied outpatient pharmacy by developing suitable queuing theory and simulation technique. A descriptive-analytical study conducted in a military hospital in Iran, Tehran in 2013. A sample of 220 patients referred to the outpatient pharmacy of the hospital in two shifts, morning and evening, was selected to collect the necessary data to determine the arrival rate, service rate, and other data needed to calculate the patients flow and queuing network performance variables. After the initial analysis of collected data using the software SPSS 18, the pharmacy queuing network performance indicators were calculated for both shifts. Then, based on collected data and to provide appropriate solutions, the queuing system of current situation for both shifts was modeled and simulated using the software ARENA 12 and 4 scenarios were explored. Results showed that the queue characteristics of the studied pharmacy during the situation analysis were very undesirable in both morning and evening shifts. The average numbers of patients in the pharmacy were 19.21 and 14.66 in the morning and evening, respectively. The average times spent in the system by clients were 39 minutes in the morning and 35 minutes in the evening. The system utilization in the morning and evening were, respectively, 25% and 21%. The simulation results showed that reducing the staff in the morning from 2 to 1 in the receiving prescriptions stage didn't change the queue performance indicators. Increasing one staff in filling prescription drugs could cause a decrease of 10 persons in the average queue length and 18 minutes and 14 seconds in the average waiting time. On the other hand, simulation results showed that in the evening, decreasing the staff

  18. 23 CFR 661.43 - Can other sources of funds be used to finance a queued project in advance of receipt of IRRBP funds?

    Science.gov (United States)

    2010-04-01

    ... PROGRAM § 661.43 Can other sources of funds be used to finance a queued project in advance of receipt of... 23 Highways 1 2010-04-01 2010-04-01 false Can other sources of funds be used to finance a queued project in advance of receipt of IRRBP funds? 661.43 Section 661.43 Highways FEDERAL HIGHWAY...

  19. Research on Performance Evaluation of Biological Database based on Layered Queuing Network Model under the Cloud Computing Environment

    Directory of Open Access Journals (Sweden)

    Zhengbin Luo

    2013-06-01

    Full Text Available To evaluate the performance of biological database based on layered queuing network model and under cloud computing environment is a premise, as well as an important step for biological database optimization. Based on predecessors’ researches concerning computer software and hardware performance evaluation under cloud environment, the study has further constructed a model system to evaluate the performance of biological database based on layered queuing network model and under cloud environment. Moreover, traditional layered queuing network model is also optimized and upgraded in this process. After having constructed the performance evaluation system, the study applies laboratory experiment method to test the validity of the constructed performance model. Shown by the test result, this model is effective in evaluating the performance of biological system under cloud environment and the predicted result is quite close to the tested result. This has demonstrated the validity of the model in evaluating the performance of biological database.

  20. A queuing-theory-based interval-fuzzy robust two-stage programming model for environmental management under uncertainty

    Science.gov (United States)

    Sun, Y.; Li, Y. P.; Huang, G. H.

    2012-06-01

    In this study, a queuing-theory-based interval-fuzzy robust two-stage programming (QB-IRTP) model is developed through introducing queuing theory into an interval-fuzzy robust two-stage (IRTP) optimization framework. The developed QB-IRTP model can not only address highly uncertain information for the lower and upper bounds of interval parameters but also be used for analysing a variety of policy scenarios that are associated with different levels of economic penalties when the promised targets are violated. Moreover, it can reflect uncertainties in queuing theory problems. The developed method has been applied to a case of long-term municipal solid waste (MSW) management planning. Interval solutions associated with different waste-generation rates, different waiting costs and different arriving rates have been obtained. They can be used for generating decision alternatives and thus help managers to identify desired MSW management policies under various economic objectives and system reliability constraints.

  1. Modeling and simulation of queuing system for customer service improvement: A case study

    Science.gov (United States)

    Xian, Tan Chai; Hong, Chai Weng; Hawari, Nurul Nazihah

    2016-10-01

    This study aims to develop a queuing model at UniMall by using discrete event simulation approach in analyzing the service performance that affects customer satisfaction. The performance measures that considered in this model are such as the average time in system, the total number of student served, the number of student in waiting queue, the waiting time in queue as well as the maximum length of buffer. ARENA simulation software is used to develop a simulation model and the output is analyzed. Based on the analysis of output, it is recommended that management of UniMall consider introducing shifts and adding another payment counter in the morning.

  2. Optimal scaling of average queue sizes in an input-queued switch: an open problem

    OpenAIRE

    Shah, Devavrat; Tsitsiklis, John N.; Zhong, Yuan

    2011-01-01

    We review some known results and state a few versions of an open problem related to the scaling of the total queue size (in steady state) in an n×n input-queued switch, as a function of the port number n and the load factor ρ. Loosely speaking, the question is whether the total number of packets in queue, under either the maximum weight policy or under an optimal policy, scales (ignoring any logarithmic factors) as O(n/(1 − ρ)).

  3. Queuing Analysis for IEEE 802.11e Networks in Non-Saturation Environments

    Directory of Open Access Journals (Sweden)

    Eui-Jik Kim

    2012-04-01

    Full Text Available This paper presents an analytical model for the performance evaluation of an IEEE 802.11e network in non‐saturation environments. We first characterize the probability distribution of the MAC layer packet service time. Based on the probability distribution model of the MAC layer packet service time, we then study the queuing performance of the wireless local area networks (WLANs at different traffic loads based on the IEEE 802.11e MAC protocol. The numerical results show that we can choose a feasible number and bandwidth of the node which determines the system performance that a user demands.

  4. DWF2Q+: A Novel and Efficient Packet Fair Queuing Algorithm

    Institute of Scientific and Technical Information of China (English)

    TUXiaodong; LILemin; WANGGuoxing

    2003-01-01

    A novel packet fair queuing algorithm,Deficit WF2Q+ (DWF2Q+) is proposed in this paper,which combines the characteristics of deficit round robin(DRR) and WF2Q+. DWF2Q+ achieves better delay properties than DRR and lower implementing complex-ity than WF2Q+. DWF2Q+can be implemented by a simple grouping architecture, called grouping per service frequency (GPSF), which can support a large number of sessions. Simulations show that DWF2Q+ has desirable low delay and fairness properties, which make it applica-ble to support both real time and best effort services in the Internet.

  5. On the application of queuing theory for analysis of twin data.

    Science.gov (United States)

    Kuravsky, L S; Malykh, S B

    2000-06-01

    A mathematical model based on queuing theory is used to study the dynamics of environmental influence on twin pairs. The model takes into consideration genetic factors and effects of nonshared environment. Histograms are exploited as base analysed characteristics, with the method of minimum chi-square yielding estimated characteristics. The proposed technique was applied to analysis of longitudinal data for MZ and DZ twins. It was shown that the same environment impact may yield different contributions to final variances of the IQ parameters under investigation. Magnitudes of these contributions depend on the genetic factor represented by distributions of an analysed parameter at the point of birth.

  6. Innovative Knowledge Management At Disney: Human Capital And Queuing Solutions For Services

    Directory of Open Access Journals (Sweden)

    Rachelle F. Cope

    2011-04-01

    Full Text Available It is well known that most activities in which a service is provided require customers to wait in a queue during the experience. One thing that is inherent in waiting lines is the universal dislike for the process. In fact, the feelings and opinions developed in waiting lines influence the customer’s perception of the awaited experience. In this paper, Disney is used as a case study for queuing solutions. In particular, we examine their implementation of Knowledge Management (KM solutions to improve the waiting line process. The use of Disney cast members as human capital combined with the knowledge of customer preferences has made the FASTPASS an innovative solution to enhance queuing in the Disney theme parks. In the past, KM has been thought of as the collection of technological assets and managerial policies that compensate for information failures. In fact, the individual’s need for human interaction provides the richest opportunity for knowledge acquisition. Disney’s ability to capture customers in virtual queues while giving them a pleasurable waiting experience has made them a leader in KM initiatives in the service industry.

  7. A Novel Queuing Method for DiffServ Traffic over Resilient Packet Ring Networks

    Directory of Open Access Journals (Sweden)

    Hadi Khosravi

    2008-09-01

    Full Text Available Resilient Packet Ring (RPR is a new kind of metropolitan area network which technically provides complete flexibility in defining service classes that can be sold to the end user. On the other side, the IETF Diffserv group has created specific definitions for class based services over IP networks. Hereby, we are going to propose a more effective queuing for RPR which considers the mapping between DiffServ and RPR QOS provisioning mechanisms. This novel method is used to support the requested quality for IP over RPR delivery. Only the standard PHBs have been considered for such a mapping consisting EF (expedited forwarding, AF (assured forwarding, and default PHB. The EF class is preferred to be transmitted via class A, while AF class is more distinctive. AF includes four different flows each including up to three drop precedence. To improve the quality for AF flows, we have proposed a multi-level queuing method considering different levels of drop precedence. The default PHB is also preferred to be mapped as class C traffic. Our proposed method has been investigated using some simulations over NS2. The simulation results have shown superior performance in terms of loss and delay parameters.

  8. Threshold-based queuing system for performance analysis of cloud computing system with dynamic scaling

    Energy Technology Data Exchange (ETDEWEB)

    Shorgin, Sergey Ya.; Pechinkin, Alexander V. [Institute of Informatics Problems, Russian Academy of Sciences (Russian Federation); Samouylov, Konstantin E.; Gaidamaka, Yuliya V.; Gudkova, Irina A.; Sopin, Eduard S. [Telecommunication Systems Department, Peoples’ Friendship University of Russia (Russian Federation)

    2015-03-10

    Cloud computing is promising technology to manage and improve utilization of computing center resources to deliver various computing and IT services. For the purpose of energy saving there is no need to unnecessarily operate many servers under light loads, and they are switched off. On the other hand, some servers should be switched on in heavy load cases to prevent very long delays. Thus, waiting times and system operating cost can be maintained on acceptable level by dynamically adding or removing servers. One more fact that should be taken into account is significant server setup costs and activation times. For better energy efficiency, cloud computing system should not react on instantaneous increase or instantaneous decrease of load. That is the main motivation for using queuing systems with hysteresis for cloud computing system modelling. In the paper, we provide a model of cloud computing system in terms of multiple server threshold-based infinite capacity queuing system with hysteresis and noninstantanuous server activation. For proposed model, we develop a method for computing steady-state probabilities that allow to estimate a number of performance measures.

  9. Using multi-class queuing network to solve performance models of e-business sites.

    Science.gov (United States)

    Zheng, Xiao-ying; Chen, De-ren

    2004-01-01

    Due to e-business's variety of customers with different navigational patterns and demands, multi-class queuing network is a natural performance model for it. The open multi-class queuing network(QN) models are based on the assumption that no service center is saturated as a result of the combined loads of all the classes. Several formulas are used to calculate performance measures, including throughput, residence time, queue length, response time and the average number of requests. The solution technique of closed multi-class QN models is an approximate mean value analysis algorithm (MVA) based on three key equations, because the exact algorithm needs huge time and space requirement. As mixed multi-class QN models, include some open and some closed classes, the open classes should be eliminated to create a closed multi-class QN so that the closed model algorithm can be applied. Some corresponding examples are given to show how to apply the algorithms mentioned in this article. These examples indicate that multi-class QN is a reasonably accurate model of e-business and can be solved efficiently.

  10. A Node Model Capturing Turning Lane Capacity and Physical Queuing for the Dynamic Network Loading Problem

    Directory of Open Access Journals (Sweden)

    Mingxia Gao

    2012-01-01

    Full Text Available An analytical dynamic node-based model is proposed to represent flows on a traffic network and to be utilized as an integral part of a dynamic network loading (DNL process by solving a continuous DNL problem. The proposed model formulation has an integrate base to be structured with a link load computing component, where physical queuing and its influence were explicitly taken into account by dividing a link into two parts: running part and queuing part. The solution to the model is obtained by a hybridization algorithm of simulation and analytical approach, where an iteration process is conducted to update time-dependent network flow conditions after a reasonable discretization of the problem. The performance of the proposed model, as a DNL model, is tested on a sample network. It is seen that the proposed model provides consistent approximations to link flow dynamics. The dynamic node model proposed in this paper is unique in that it explicitly models directional queue in each turning lane and the First-In-First-Out (FIFO rule at lane level rather than link level is pursued.

  11. Performance evaluation for an optical hybrid switch with circuit queued reservations

    Science.gov (United States)

    Wong, Eric W. M.; Zukerman, Moshe

    2005-11-01

    We provide here a new loss model for an optical hybrid switch that can function as an optical burst switch or optical circuit switch or both simultaneously. We introduce the feature of circuit queued reservation. That is, if a circuit request arrives and cannot find a free wavelength, and if there are not too many requests queued for reservations, it may join a queue and wait until such wavelength becomes available. We first present an analysis based on a 3-dimension state-space Markov chain that provides exact results for the blocking probabilities of bursts and circuits. We also provide results for the proportion of circuits that are delayed and the mean delay of the circuits that are delay. Because it is difficult to exactly compute the blocking probability in realistic scenarios with a large number of wavelengths, we derive computationally scalable and accurate approximations which are based on reducing the 3-dimension state space into a single dimension. These scalable approximations that can produce performance results in a fraction of a second can readily enable switch dimensioning.

  12. DOMAIN-DRIVEN DESIGN APPLICATION AND IMPLEMENTATION OF INFORMATION SYSTEMS FOR CLIENTS QUEUING SUBJECT AREAS

    Directory of Open Access Journals (Sweden)

    P. P. Oleynik

    2015-11-01

    Full Text Available The paper deals with domain-driven design applicability of information systems for client queuing subject areas. The following optimality criteria were put forward for the final implementation: the possibility of automation with a single system both for small institution and a whole network of institutions; advanced graphical interface with support for sensor screens; implementation of multi-users account of orders from clients; flexible application architecture with the ability of future enhancement; ability of integration with a variety of peripherals. The necessity of each criterion definition is shown. For implementability estimation, test information system was designed, automating the queuing system. Unified modeling language UML is used. Description of each class functionality is given and the association with other classes as well. Attention is paid to the design of tree (hierarchical structures and selection procedure of base classes based on the analysis of existing common attributes. For the system implementation, its own development environment SharpArchitect RAD Studio is used, offering MDA approach for implementation of systems based on standardized meta object system. A graphical view of order form developed prototype is presented, composition and structure are described, and notation developed by the author is given simplifying the prototyping process. Approaches to differentiation of access rights for different user roles are shown. Conformity of the received implementation to each selected optimality criterion is determined. Recommendations for further system development are given.

  13. Using multi-class queuing network to solve performance models of e-business sites

    Institute of Scientific and Technical Information of China (English)

    郑小盈; 陈德人

    2004-01-01

    Due to e-business' s variety of customers with different navigational patterns and demands, multiclass queuing network is a natural performance model for it. The open multi-class queuing network(QN) models are based on the assumption that no service center is saturated as a result of the combined loads of all the classes. Several formulas are used to calculate performance measures, including throughput, residence time, queue length, response time and the average number of requests. The solution technique of closed multi-class QN models is an approximate mean value analysis algorithm (MVA) based on three key equations, because the exact algorithm needs huge time and space requirement. As mixed multi-class QN models, include some open and some closed classes, the open classes should be eliminated to create a closed multi-class QN so that the closed model algorithm can be applied. Some corresponding examples are given to show how to apply the algorithms mentioned in this article. These examples indicate that multi-class QN is a reasonably accurate model of e-business and can be solved efficiently.

  14. Using multi-class queuing network to solve performance models of e-business sites

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xiao-ying (郑小盈); CHEN De-ren (陈德人)

    2004-01-01

    Due to e-business's variety of customers with different navigational patterns and demands, multi-class queuing network is a natural performance model for it. The open multi-class queuing network(QN) models are based on the assumption that no service center is saturated as a result of the combined loads of all the classes. Several formulas are used to calculate performance measures, including throughput, residence time, queue length, response time and the average number of requests. The solution technique of closed multi-class QN models is an approximate mean value analysis algorithm (MVA) based on three key equations, because the exact algorithm needs huge time and space requirement. As mixed multi-class QN models, include some open and some closed classes, the open classes should be eliminated to create a closed multi-class QN so that the closed model algorithm can be applied. Some corresponding examples are given to show how to apply the algorithms mentioned in this article. These examples indicate that multi-class QN is a reasonably accurate model of e-business and can be solved efficiently.

  15. Queuing theory to guide the implementation of a heart failure inpatient registry program.

    Science.gov (United States)

    Zai, Adrian H; Farr, Kit M; Grant, Richard W; Mort, Elizabeth; Ferris, Timothy G; Chueh, Henry C

    2009-01-01

    OBJECTIVE The authors previously implemented an electronic heart failure registry at a large academic hospital to identify heart failure patients and to connect these patients with appropriate discharge services. Despite significant improvements in patient identification and connection rates, time to connection remained high, with an average delay of 3.2 days from the time patients were admitted to the time connections were made. Our objective for this current study was to determine the most effective solution to minimize time to connection. DESIGN We used a queuing theory model to simulate 3 different potential solutions to decrease the delay from patient identification to connection with discharge services. MEASUREMENTS The measures included average rate at which patients were being connected to the post discharge heart failure services program, average number of patients in line, and average patient waiting time. RESULTS Using queuing theory model simulations, we were able to estimate for our current system the minimum rate at which patients need to be connected (262 patients/mo), the ideal patient arrival rate (174 patients/mo) and the maximal patient arrival rate that could be achieved by adding 1 extra nurse (348 patients/mo). CONCLUSIONS Our modeling approach was instrumental in helping us characterize key process parameters and estimate the impact of adding staff on the time between identifying patients with heart failure and connecting them with appropriate discharge services.

  16. Modified weighted fair queuing for packet scheduling in mobile WiMAX networks

    Science.gov (United States)

    Satrya, Gandeva B.; Brotoharsono, Tri

    2013-03-01

    The increase of user mobility and the need for data access anytime also increases the interest in broadband wireless access (BWA). The best available quality of experience for mobile data service users are assured for IEEE 802.16e based users. The main problem of assuring a high QOS value is how to allocate available resources among users in order to meet the QOS requirement for criteria such as delay, throughput, packet loss and fairness. There is no specific standard scheduling mechanism stated by IEEE standards, which leaves it for implementer differentiation. There are five QOS service classes defined by IEEE 802.16: Unsolicited Grant Scheme (UGS), Extended Real Time Polling Service (ertPS), Real Time Polling Service (rtPS), Non Real Time Polling Service (nrtPS) and Best Effort Service (BE). Each class has different QOS parameter requirements for throughput and delay/jitter constraints. This paper proposes Modified Weighted Fair Queuing (MWFQ) scheduling scenario which was based on Weighted Round Robin (WRR) and Weighted Fair Queuing (WFQ). The performance of MWFQ was assessed by using above five QoS criteria. The simulation shows that using the concept of total packet size calculation improves the network's performance.

  17. Out-of-Sequence Prevention for Multicast Input-Queuing Space-Memory-Memory Clos-Network

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah; Berger, Michael Stübert

    2011-01-01

    This paper proposes two cell dispatching algorithms for the input-queuing space-memory-memory (IQ-SMM) Closnetwork to reduce out-of-sequence (OOS) for multicast traffic. The frequent connection pattern change of DSRR results in a severe OOS problem. Based on the principle of DSRR, MFDSRR is able...

  18. Queuing Theory Based Co-Channel Interference Analysis Approach for High-Density Wireless Local Area Networks

    Science.gov (United States)

    Zhang, Jie; Han, Guangjie; Qian, Yujie

    2016-01-01

    Increased co-channel interference (CCI) in wireless local area networks (WLANs) is bringing serious resource constraints to today’s high-density wireless environments. CCI in IEEE 802.11-based networks is inevitable due to the nature of the carrier sensing mechanism however can be reduced by resource optimization approaches. That means the CCI analysis is basic, but also crucial for an efficient resource management. In this article, we present a novel CCI analysis approach based on the queuing theory, which considers the randomness of end users’ behavior and the irregularity and complexity of network traffic in high-density WLANs that adopts the M/M/c queuing model for CCI analysis. Most of the CCIs occur when multiple networks overlap and trigger channel contentions; therefore, we use the ratio of signal-overlapped areas to signal coverage as a probabilistic factor to the queuing model to analyze the CCI impacts in highly overlapped WLANs. With the queuing model, we perform simulations to see how the CCI influences the quality of service (QoS) in high-density WLANs. PMID:27563896

  19. Queuing Theory Based Co-Channel Interference Analysis Approach for High-Density Wireless Local Area Networks.

    Science.gov (United States)

    Zhang, Jie; Han, Guangjie; Qian, Yujie

    2016-08-23

    Increased co-channel interference (CCI) in wireless local area networks (WLANs) is bringing serious resource constraints to today's high-density wireless environments. CCI in IEEE 802.11-based networks is inevitable due to the nature of the carrier sensing mechanism however can be reduced by resource optimization approaches. That means the CCI analysis is basic, but also crucial for an efficient resource management. In this article, we present a novel CCI analysis approach based on the queuing theory, which considers the randomness of end users' behavior and the irregularity and complexity of network traffic in high-density WLANs that adopts the M/M/c queuing model for CCI analysis. Most of the CCIs occur when multiple networks overlap and trigger channel contentions; therefore, we use the ratio of signal-overlapped areas to signal coverage as a probabilistic factor to the queuing model to analyze the CCI impacts in highly overlapped WLANs. With the queuing model, we perform simulations to see how the CCI influences the quality of service (QoS) in high-density WLANs.

  20. A Case Study of Employing A Single Server Nonpreemptive Priority Queuing Model at ATM Machine

    Directory of Open Access Journals (Sweden)

    Abdullah Furquan

    2015-08-01

    Full Text Available This paper discusses a case study of employing a single server nonpreemptivepriorityqueuing model [1]at ATM machine which originally operates on M/M/1 model. In this study we have taken two priority classes of people in following order:- .Priority class 1- woman .Priority class 2- man Sometimea long queue is formed at ATMmachine (single serverbut the bank management don’t have enough money to invest on installing new ATM machine.In this situation we want to apply single server nonpreemptive priority queuing model.The security guard at the ATM will divide the customers in two category and arrange the customers in the above said priority order Thuspriority class 1 people willreceive theatm service ahead of priority class 2 people.This will reduce the waiting time of priority class 1 people. Of course by doing this the waiting time of priority class 2will increase. This is ok as long as the increment in waiting time of priority class2 people is reasonable and within the tolerable limitof priority class 2people.This will be true when percentage of priority class 1 people is relatively less as compared to priority class 2 people To know the attitude and tolerable limit of priority class 2 people towards the single server non preemtive priority model a sample survey has been done on the incomingpriority class 2 population at the atm machine.Against this background, the queuing process is employed with emphasis to Poisson distribution to assess the waiting time. The data for this study was collected from primary source and is limited to ATM service point of state bank of India located at Ramesh chowk, Aurangabad, bihar, India.. The assistance of three colleague was sought in collecting the data. The Interarrival time and service time data was collected during busy working hours (i.e. 10.30am to 4:00pm during the first 60 days. A sample survey was done to know the attitude and tolerable limit of priority class 2people towards the single server

  1. Application of queuing theory to patient satisfaction at a tertiary hospital in Nigeria

    Directory of Open Access Journals (Sweden)

    Nkeiruka Ameh

    2013-01-01

    Full Text Available Background: Queuing theory is the mathematical approach to the analysis of waiting lines in any setting where arrival rate of subjects is faster than the system can handle. It is applicable to healthcare settings where the systems have excess capacity to accommodate random variations. Materials and Methods: A cross-sectional descriptive survey was done. Questionnaires were administered to patients who attended the general outpatient department. Observations were also made on the queuing model and the service discipline at the clinic. Questions were meant to obtain demographic characteristics and the time spent on the queue by patients before being seen by a doctor, time spent with the doctor, their views about the time spent on the queue and useful suggestions on how to reduce the time spent on the queue. A total of 210 patients were surveyed. Results: Majority of the patients (164, 78.1% spent 2 h or less on the queue before being seen by a doctor and less than 1 h to see the doctor. Majority of the patients (144, 68.5% were satisfied with the time they spent on the queue before being seen by a doctor. Useful suggestions proffered by the patients to decrease the time spent on the queue before seeing a doctor at the clinic included: that more doctors be employed (46, 21.9%, that doctors should come to work on time (25, 11.9%, that first-come-first served be observed strictly (32, 15.2% and others suggested that the records staff should desist from collecting bribes from patients in order to place their cards before others. The queuing method employed at the clinic is the multiple single channel type and the service discipline is priority service. The patients who spent less time on the queue (<1 h before seeing the doctor were more satisfied than those who spent more time ( P < 0.05. Conclusion: The study has revealed that majority of the patients were satisfied with the practice at the general outpatient department. However, there is a need to

  2. Application of Queuing Analytic Theory to Decrease Waiting Times in Emergency Department: Does it Make Sense?

    Science.gov (United States)

    Alavi-Moghaddam, Mostafa; Forouzanfar, Reza; Alamdari, Shahram; Shahrami, Ali; Kariman, Hamid; Amini, Afshin; Pourbabaee, Shokooh; Shirvani, Armin

    2012-01-01

    Patients who receive care in an emergency department (ED), are usually unattended while waiting in queues. This study was done to determine, whether the application of queuing theory analysis might shorten the waiting times of patients admitted to emergency wards. This was an operational study to use queuing theory analysis in the ED. In the first phase, a field study was conducted to delineate the performance of the ED and enter the data obtained into simulator software. In the second phase, "ARENA" software was used for modeling, analysis, creating a simulation and improving the movement of patients in the ED. Validity of the model was confirmed through comparison of the results with the real data using the same instrument. The third phase of the study concerned modeling in order to assess the effect of various operational strategies, on the queue waiting time of patients who were receiving care in the ED. In the first phase, it was shown that 47.7% of the 3000 patient records were cases referred for trauma treatment, and the remaining 52.3% were referred for non-trauma services. A total of 56% of the cases were male and 44% female. Maximum input was 4.5 patients per hour and the minimum input was 0.5 per hour. The average length of stay for patients in the trauma section was three hours, while for the non-trauma section it was four hours. In the second phase, modeling was tested with common scenarios. In the third phase, the scenario with the addition of one or more senior emergency resident(s) on each shift resulted in a decreased length of stay from 4 to 3.75 hours. Moreover, the addition of one bed to the Intensive Care Unit (ICU) and/or Critical Care Unit (CCU) in the study hospital, reduced the occupancy rate of the nursing service from 76% to 67%. By adding another clerk to take electrocardiograms (ECG) in the ED, the average time from a request to performing the procedure is reduced from 26 to 18 minutes. Furthermore, the addition of 50% more staff to the

  3. Application of queuing theory to patient satisfaction at a tertiary hospital in Nigeria.

    Science.gov (United States)

    Ameh, Nkeiruka; Sabo, B; Oyefabi, M O

    2013-01-01

    Queuing theory is the mathematical approach to the analysis of waiting lines in any setting where arrival rate of subjects is faster than the system can handle. It is applicable to healthcare settings where the systems have excess capacity to accommodate random variations. A cross-sectional descriptive survey was done. Questionnaires were administered to patients who attended the general outpatient department. Observations were also made on the queuing model and the service discipline at the clinic. Questions were meant to obtain demographic characteristics and the time spent on the queue by patients before being seen by a doctor, time spent with the doctor, their views about the time spent on the queue and useful suggestions on how to reduce the time spent on the queue. A total of 210 patients were surveyed. Majority of the patients (164, 78.1%) spent 2 h or less on the queue before being seen by a doctor and less than 1 h to see the doctor. Majority of the patients (144, 68.5%) were satisfied with the time they spent on the queue before being seen by a doctor. Useful suggestions proffered by the patients to decrease the time spent on the queue before seeing a doctor at the clinic included: that more doctors be employed (46, 21.9%), that doctors should come to work on time (25, 11.9%), that first-come-first served be observed strictly (32, 15.2%) and others suggested that the records staff should desist from collecting bribes from patients in order to place their cards before others. The queuing method employed at the clinic is the multiple single channel type and the service discipline is priority service. The patients who spent less time on the queue (<1 h) before seeing the doctor were more satisfied than those who spent more time (P < 0.05). The study has revealed that majority of the patients were satisfied with the practice at the general outpatient department. However, there is a need to employ measures to respond to the suggestions given by the patients

  4. Ship Lock as General Queuing System with Batch Arrivals and Batch Service

    Directory of Open Access Journals (Sweden)

    Zoran Radmilović

    2007-11-01

    Full Text Available The real lock operations with ships and barge convoys areconsidered dependent on the transport technologies applied, ormore precisely, the kinds of ships/convoys requiring thelockage. The fleet can be divided as follows: (1 groups of singleships, (2 pushed and pulled tows of barges and (3 differentcombinations of previous systems (1 and (2. The groups ofships and tows passing through the lock have extremely stochasticcharacteristics thus forming various arrivals and setvicetime patterns. It means that uniform navigation or strongscheduling between locks and lock operations are not possibleeven though highly sophisticated equipment is at disposal.Therefore, in this paper an analytical method was developedusing bulk queuing systems for the analysis and planning oflock requirements supporting it with numerical example. Thedeveloped methodology can be applied to determine the meanqueue length of ships - convoys at lock anchorage, withoutblocking behaviour between upstream and downstream navigationfor single-lane traffic.

  5. Fuzzy-Logic Adaptive Queuing for a Heuristic TCP Performance in Mobile Wireless Networks

    Directory of Open Access Journals (Sweden)

    Ghaida A. AL-Suhail

    2012-06-01

    Full Text Available In this paper, we propose a new Fuzzy-Logic Adaptive Queuing controller (FLAQ based on a classical Random Early Detection (RED algorithm in wireless cellular network. The controller predicts dynamically the packet dropping rate and the corresponding average queue length. It relies on the average queue length at the base station router and the packet loss rate caused by the channel variations in mobile environment; assuming there is no buffer overflow due to the congestion. Using this model, a heuristic TCP performance can be estimated over a time-varying channel under different conditions of user’s mobility. The results show a significant improvement in TCP throughput performance when the user’s mobility is below 5 m/s; and becomes constant (i.e., close to i.i.d beyond this speed especially at 5% of predefined packet error rate.

  6. Establishing Performance Evaluation Model with Queuing Theory in NoC

    Directory of Open Access Journals (Sweden)

    Tao He

    2013-10-01

    Full Text Available The transmission delay is an important index of the system performance of NoC (Network on Chip. Although the method of simulation-based can get accurate transmission delay, the simulation requires time consuming and a large number of test vectors. Especially in the study of some algorithms, such as mapping algorithms, buffer allocation algorithm, the simulation method is not applicable. To solve the above problems, the paper uses queuing theory to study the establishment of a NoC delay model. The model considers the limited buffer of routing unit and virtual channel technology for network transmission delay and proposes solving algorithm of the delay model based on reverse deduction method. The simulation shows that this model used to analyze the application-specific data transmission delay has smaller average error (reduced by 8% and higher evaluation efficiency (increased by more than 30 times, which provide designers an efficient method of performance evaluation.  

  7. A soft computing-based approach to optimise queuing-inventory control problem

    Science.gov (United States)

    Alaghebandha, Mohammad; Hajipour, Vahid

    2015-04-01

    In this paper, a multi-product continuous review inventory control problem within batch arrival queuing approach (MQr/M/1) is developed to find the optimal quantities of maximum inventory. The objective function is to minimise summation of ordering, holding and shortage costs under warehouse space, service level and expected lost-sales shortage cost constraints from retailer and warehouse viewpoints. Since the proposed model is Non-deterministic Polynomial-time hard, an efficient imperialist competitive algorithm (ICA) is proposed to solve the model. To justify proposed ICA, both ganetic algorithm and simulated annealing algorithm are utilised. In order to determine the best value of algorithm parameters that result in a better solution, a fine-tuning procedure is executed. Finally, the performance of the proposed ICA is analysed using some numerical illustrations.

  8. Weighted Round Robin and Rate Limiter based Fair Queuing for WRR

    Directory of Open Access Journals (Sweden)

    Tomáš Balogh

    2015-04-01

    Full Text Available In this paper we present a new packet scheduling method based on parallel usage of multiple WRR schedulers, rate limiters and output bandwidth calculation for modern NGN networks. The main idea of the presented method is to provide queueing fairness within queues. The method provides the same results in output bandwidth allocation as the compared algorithm, while within one queue flows with different packet size and arrival rates gets the same output bandwidth. With this method we are able to achieve the overall result of bandwidth assignment as algorithms like WRR, WFQ, WRRPQ and LLQ by only changing the mathematical model used to calculate the bandwidth assignment. We call this method Weighted Round Robin and Rate Limiter based Fair Queuing (WRRRLbFQ. We prove the model outcome with simulation results using NS2 simulator and compare the behavior with the WRR scheduler.

  9. Optimal Allocation of Changing Station for Electric Vehicle Based on Queuing Theory

    Directory of Open Access Journals (Sweden)

    Yagang Zhang

    2016-11-01

    Full Text Available Electric vehicle as the main development direction of the future automotive industry, has gained attention worldwide. The rationality of the planning and construction of the power station, as the foundation of energy supply, is an important premise for the development of electric vehicles. In full consideration of the electric demand and electricity consumption, this paper proposes a new construction mode in which charging station and centralized charging station are appropriately combined and presents a location optimization model. Not only can this model be applied to determine the appropriate location for the power station, but it can use the queuing theory to determine the optimal number of power equipment, with which we can achieve the minimum costs. Finally, taking a certain city as an example, the optimum plan for power station is calculated by using this model, which provides an important reference for the study of electric vehicle infrastructure planning.

  10. An Integrated Model of Patient and Staff Satisfaction Using Queuing Theory.

    Science.gov (United States)

    Komashie, Alexander; Mousavi, Ali; Clarkson, P John; Young, Terry

    2015-01-01

    This paper investigates the connection between patient satisfaction, waiting time, staff satisfaction, and service time. It uses a variety of models to enable improvement against experiential and operational health service goals. Patient satisfaction levels are estimated using a model based on waiting (waiting times). Staff satisfaction levels are estimated using a model based on the time spent with patients (service time). An integrated model of patient and staff satisfaction, the effective satisfaction level model, is then proposed (using queuing theory). This links patient satisfaction, waiting time, staff satisfaction, and service time, connecting two important concepts, namely, experience and efficiency in care delivery and leading to a more holistic approach in designing and managing health services. The proposed model will enable healthcare systems analysts to objectively and directly relate elements of service quality to capacity planning. Moreover, as an instrument used jointly by healthcare commissioners and providers, it affords the prospect of better resource allocation.

  11. Performance Analysis of an Energy Efficient Femtocell Network Using Queuing Theory

    Directory of Open Access Journals (Sweden)

    Wanod Kumar

    2013-07-01

    Full Text Available The energy expenditure of cellular networks is increasing rapidly due to high demand of data services by the subscribers. This subsequently gives rise to the CO2 emission which is a critical issue nowadays. A hybrid cellular network comprised of macrocell and several femtocells is required to achieve reliability, continuous connectivity, and energy efficiency. To address the issue of energy efficiency, in this paper we present a queuing model of an energy efficient femtocell network. The transmission of data traffic in this type of network is modeled using M/M/1 queue where server FAP (Femtocell Access Point takes vacation to save energy during inactivity period. The network model is solved using a MGM (Matrix Geometric Method. The performance of the system is evaluated in terms of average system delay and power savings for different sleep cycle durations. Results reveal that the maximum energy can be saved with higher sleep cycle duration at a cost of increased system delay

  12. Queuing Game Theory Based Optimal Routing Scheme for Heterogeneous Users over Space Information Networks

    Directory of Open Access Journals (Sweden)

    Chao Guo

    2017-01-01

    Full Text Available An optimal routing scheme in space information networks was presented to balance network loads for heterogeneous users. According to the competition among the nodes, the model was built based on queuing game theory. The virtual routing platform was in charge of resources allocation and route selection. It got user’s gain to decide which node the user joined in. Owning to the existing of heterogeneous users, an optimal admission fee needed to be obtained to avoid congestion. In our model, firstly, the whole welfare of the system was formulated. Then the optimal admission fee was calculated through maximizing the whole welfare. Meanwhile, the average maximum queue length was generated to set the buffer space of the node. At last, a routing factor was introduced into the route algorithm in order that the optimal routing could be selected by heterogeneous users. As a result, the system welfare reaches the maximum.

  13. Modeling panel detection frequencies by queuing system theory: an application in gas chromatography olfactometry.

    Science.gov (United States)

    Bult, Johannes H F; van Putten, Bram; Schifferstein, Hendrik N J; Roozen, Jacques P; Voragen, Alphons G J; Kroeze, Jan H A

    2004-10-01

    In continuous vigilance tasks, the number of coincident panel responses to stimuli provides an index of stimulus detectability. To determine whether this number is due to chance, panel noise levels have been approximated by the maximum coincidence level obtained in stimulus-free conditions. This study proposes an alternative method by which to assess noise levels, derived from queuing system theory (QST). Instead of critical coincidence levels, QST modeling estimates the duration of coinciding responses in the absence of stimuli. The proposed method has the advantage over previous approaches that it yields more reliable noise estimates and allows for statistical testing. The method was applied in an olfactory detection experiment using 16 panelists in stimulus-present and stimulus-free conditions. We propose that QST may be used as an alternative to signal detection theory for analyzing data from continuous vigilance tasks.

  14. Improved virtual queuing and dynamic EPD techniques for TCP over ATM

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.; Siu, K.Y.; Ren, W.

    1998-11-01

    It is known that TCP throughput can degrade significantly over UBR service in a congested ATM network, and the early packet discard (EPD) technique has been proposed to improve the performance. However, recent studies show that EPD cannot ensure fairness among competing VCs in a congested network, but the degree of fairness can be improved using various forms of fair buffer allocation techniques. The authors propose an improved scheme that utilizes only a single shared FIFO queue for all VCs and admits simple implementation for high speed ATM networks. The scheme achieves nearly perfect fairness and throughput among multiple TCP connections, comparable to the expensive per-VC queuing technique. Analytical and simulation results are presented to show the validity of this new scheme and significant improvement in performance as compared with existing fair buffer allocation techniques for TCP over ATM.

  15. Final Report for ?Queuing Network Models of Performance of High End Computing Systems?

    Energy Technology Data Exchange (ETDEWEB)

    Buckwalter, J

    2005-09-28

    The primary objective of this project is to perform general research into queuing network models of performance of high end computing systems. A related objective is to investigate and predict how an increase in the number of nodes of a supercomputer will decrease the running time of a user's software package, which is often referred to as the strong scaling problem. We investigate the large, MPI-based Linux cluster MCR at LLNL, running the well-known NAS Parallel Benchmark (NPB) applications. Data is collected directly from NPB and also from the low-overhead LLNL profiling tool mpiP. For a run, we break the wall clock execution time of the benchmark into four components: switch delay, MPI contention time, MPI service time, and non-MPI computation time. Switch delay is estimated from message statistics. MPI service time and non-MPI computation time are calculated directly from measurement data. MPI contention is estimated by means of a queuing network model (QNM), based in part on MPI service time. This model of execution time validates reasonably well against the measured execution time, usually within 10%. Since the number of nodes used to run the application is a major input to the model, we can use the model to predict application execution times for various numbers of nodes. We also investigate how the four components of execution time scale individually as the number of nodes increases. Switch delay and MPI service time scale regularly. MPI contention is estimated by the QNM submodel and also has a fairly regular pattern. However, non-MPI compute time has a somewhat irregular pattern, possibly due to caching effects in the memory hierarchy. In contrast to some other performance modeling methods, this method is relatively fast to set up, fast to calculate, simple for data collection, and yet accurate enough to be quite useful.

  16. Aplicação da teoria das filas em serviços bancários/Application of queuing theory in banking

    National Research Council Canada - National Science Library

    Vitor Costa de Lima; Rosley Anholon; Izabela Simon Rampasso; Osvaldo Luiz Gonçalves Quelhas

    2016-01-01

      Bearing in mind the intense competition in the current economy and the increasing necessity of having more customers and keeping them loyal, this paper aims to apply the well known Queuing Theory in...

  17. A hybrid genetic algorithm-queuing multi-compartment model for optimizing inpatient bed occupancy and associated costs.

    Science.gov (United States)

    Belciug, Smaranda; Gorunescu, Florin

    2016-03-01

    Explore how efficient intelligent decision support systems, both easily understandable and straightforwardly implemented, can help modern hospital managers to optimize both bed occupancy and utilization costs. This paper proposes a hybrid genetic algorithm-queuing multi-compartment model for the patient flow in hospitals. A finite capacity queuing model with phase-type service distribution is combined with a compartmental model, and an associated cost model is set up. An evolutionary-based approach is used for enhancing the ability to optimize both bed management and associated costs. In addition, a "What-if analysis" shows how changing the model parameters could improve performance while controlling costs. The study uses bed-occupancy data collected at the Department of Geriatric Medicine - St. George's Hospital, London, period 1969-1984, and January 2000. The hybrid model revealed that a bed-occupancy exceeding 91%, implying a patient rejection rate around 1.1%, can be carried out with 159 beds plus 8 unstaffed beds. The same holding and penalty costs, but significantly different bed allocations (156 vs. 184 staffed beds, and 8 vs. 9 unstaffed beds, respectively) will result in significantly different costs (£755 vs. £1172). Moreover, once the arrival rate exceeds 7 patient/day, the costs associated to the finite capacity system become significantly smaller than those associated to an Erlang B queuing model (£134 vs. £947). Encoding the whole information provided by both the queuing system and the cost model through chromosomes, the genetic algorithm represents an efficient tool in optimizing the bed allocation and associated costs. The methodology can be extended to different medical departments with minor modifications in structure and parameterization. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Queuing Model for Banking System: A Comparative Study of Selected Banks in Owo Local Government Area of Ondo State, Nigeria

    Directory of Open Access Journals (Sweden)

    Raimi Oluwole Abiodun

    2015-08-01

    Full Text Available Comparative study of two selected banks (Wema & Skye Bank in Owo Local Government Area of Ondo state was investigated. The research study employed a queuing model for both banking system to measure the behavioural queuing characteristics of customers in terms of their arrival and service rate respectively. The data for the arrival and service rate of the two banks were collected simultaneously at the space of three days. The data collected was also analysed separately with respect to the queuing theory parameters ( . Findings showed that Wema bank has a high waiting service time value (0.019% which may have a negative significant effect on customers on waiting lines. When compared with Skye bank, we realized that Skye bank has an advantageous effect of service time value (0.000022% which will have a positive significant effect on customers in experiencing little or no queue at all. This clearly indicates that for optimum efficiency in the banks, there is need to increase the number of servers. Also, the result of the respective banks shows that waiting lines reduces when the number of servers increases. The analysis in this study is very effective and practical, and is hereby recommended for the management of the banks to review for better efficiency and performance.

  19. Evacuation time estimate for a total pedestrian evacuation using queuing network model and volunteered geographic information

    CERN Document Server

    Kunwar, Bharat; Johansson, Anders

    2015-01-01

    Estimating city evacuation time is a non-trivial problem due to the interaction between thousands of individual agents, giving rise to various collective phenomena, such as bottleneck formation, intermittent flow and stop-and-go waves. We present a mean field approach to draw relationships between road network spatial attributes, number of evacuees and resultant evacuation time estimate (ETE). We divide $50$ medium sized UK cities into a total of $697$ catchment areas which we define as an area where all agents share the same nearest exit node. In these catchment areas, 90% of agents are within $5.4$ km of their designated exit node. We establish a characteristic flow rate from catchment area attributes (population, distance to exit node and exit node width) and a mean flow rate in free-flow regime by simulating total evacuations using an agent based `queuing network' model. We use these variables to determine a relationship between catchment area attributes and resultant ETE. This relationship could enable e...

  20. Profit Optimization in SLA-Aware Cloud Services with a Finite Capacity Queuing Model

    Directory of Open Access Journals (Sweden)

    Yi-Ju Chiang

    2014-01-01

    Full Text Available Cloud computing realizes a utility computing paradigm by offering shared resources through an Internet-based computing. However, how a system control can enhance profit and simultaneously satisfy the service level agreements (SLAs has become one of the major interests for cloud providers. In this paper, a cloud server farm provided with finite capacity is modeled as an M/M/R/K queuing system. Revenue losses are estimated according to the system controls and impatient customer behaviors. Three important issues are solved in this paper. First, a profit function is developed in which both the system blocking loss and the user abandonment loss are evaluated in total revenue. A tradeoff between meeting system performances and reducing operating costs is conducted. Second, the effects of system capacity control and utilization on various performances of waiting time, loss probability, and final arrival rate are demonstrated. Finally, the proposed optimal profit control (OPC policy allows a cloud provider to make the optimal decision in the number of servers and system capacity, so as to maximize profit. As compared to a system without applying the OPC policy, enhancing providers’ profit and improving system performances can be obtained.

  1. Class-Based Weighted Fair Queuing Scheduling on Dual-Priority Delta Networks

    Directory of Open Access Journals (Sweden)

    D. C. Vasiliadis

    2012-01-01

    Full Text Available Contemporary networks accommodate handling of multiple priorities, aiming to provide suitable QoS levels to different traffic classes. In the presence of multiple priorities, a scheduling algorithm is employed to select each time the next packet to transmit over the data link. Class-based Weighted Fair Queuing (CBWFQ scheduling and its variations is widely used as a scheduling technique, since it is easy to implement and prevents the low-priority queues from being completely neglected during periods of high-priority traffic. By using this scheduling, low-priority queues have the opportunity to transmit packets even though the high-priority queues are not empty. In this work, the modeling, analysis and performance evaluation of a single-buffered, dual-priority multistage interconnection network (MIN operating under the CBWFQ scheduling policy is presented. Performance evaluation is conducted through simulation, and the performance measures obtained can be valuable assets for MIN designers, in order to minimize the overall deployment costs and delivering efficient systems.

  2. Modelling pedestrian travel time and the design of facilities: a queuing approach.

    Directory of Open Access Journals (Sweden)

    Khalidur Rahman

    Full Text Available Pedestrian movements are the consequence of several complex and stochastic facts. The modelling of pedestrian movements and the ability to predict the travel time are useful for evaluating the performance of a pedestrian facility. However, only a few studies can be found that incorporate the design of the facility, local pedestrian body dimensions, the delay experienced by the pedestrians, and level of service to the pedestrian movements. In this paper, a queuing based analytical model is developed as a function of relevant determinants and functional factors to predict the travel time on pedestrian facilities. The model can be used to assess the overall serving rate or performance of a facility layout and correlate it to the level of service that is possible to provide the pedestrians. It has also the ability to provide a clear suggestion on the designing and sizing of pedestrian facilities. The model is empirically validated and is found to be a robust tool to understand how well a particular walking facility makes possible comfort and convenient pedestrian movements. The sensitivity analysis is also performed to see the impact of some crucial parameters of the developed model on the performance of pedestrian facilities.

  3. A Survey of Wireless Fair Queuing Algorithms with Location-Dependent Channel Errors

    Directory of Open Access Journals (Sweden)

    Anca VARGATU

    2011-01-01

    Full Text Available The rapid development of wireless networks has brought more and more attention to topics related to fair allocation of resources, creation of suitable algorithms, taking into account the special characteristics of wireless environment and insurance fair access to the transmission channel, with delay bound and throughput guaranteed. Fair allocation of resources in wireless networks requires significant challenges, because of errors that occur only in these networks, such as location-dependent and bursty channel errors. In wireless networks, frequently happens, because interference of radio waves, that a user experiencing bad radio conditions during a period of time, not to receive resources in that period. This paper analyzes some resource allocation algorithms for wireless networks with location dependent errors, specifying the base idea for each algorithm and the way how it works. The analyzed fair queuing algorithms differ by the way they treat the following aspects: how to select the flows which should receive additional services, how to allocate these resources, which is the proportion received by error free flows and how the flows affected by errors are compensated.

  4. Modelling pedestrian travel time and the design of facilities: a queuing approach.

    Science.gov (United States)

    Rahman, Khalidur; Ghani, Noraida Abdul; Kamil, Anton Abdulbasah; Mustafa, Adli; Kabir Chowdhury, Md Ahmed

    2013-01-01

    Pedestrian movements are the consequence of several complex and stochastic facts. The modelling of pedestrian movements and the ability to predict the travel time are useful for evaluating the performance of a pedestrian facility. However, only a few studies can be found that incorporate the design of the facility, local pedestrian body dimensions, the delay experienced by the pedestrians, and level of service to the pedestrian movements. In this paper, a queuing based analytical model is developed as a function of relevant determinants and functional factors to predict the travel time on pedestrian facilities. The model can be used to assess the overall serving rate or performance of a facility layout and correlate it to the level of service that is possible to provide the pedestrians. It has also the ability to provide a clear suggestion on the designing and sizing of pedestrian facilities. The model is empirically validated and is found to be a robust tool to understand how well a particular walking facility makes possible comfort and convenient pedestrian movements. The sensitivity analysis is also performed to see the impact of some crucial parameters of the developed model on the performance of pedestrian facilities.

  5. An Efficient Computational Method for Solving Nonlinear Matrix Equstion and Its Application in Queuing Analysis

    Institute of Scientific and Technical Information of China (English)

    HUANGJun; 朱涛; 等

    1996-01-01

    The matrix analytic analysis of queues with complex arrival,vacation and service characteristics requires the solution of nonlinear matrix equation.The complexity and large dimensionality of the model require an effcient and smart algorithm for the solution.In this paper,we propose and efficient Adaptive Newton-Kantorovich(ANK) method for speeding up the algorithm solving the nonlinear matrix equation which is an inevitable step in the analysis of the queue with embedded Markov chain such as BMAP/SMSP/1/∞ queue or its discrete version.BMAP/SMSP/1/∞ is a queuing model with a Semi Markov Service time Process (SMSP) and a Batch Markovian Arfival Process(BMAP).The numerical result is presented for the discrete case of N-MMBP/D/1 queue which arises in analyzing traffic aspect of computer communication network,where MMBP is Markov Modulated Bermoulli Process.The comparisons of Adaptive Newton-Kantorovich(ANK)with Modified Newton-Kantorovich(MNK) show that ANK saves 30% of CPU tim when the number of user N is 50.

  6. T-cell activation: A queuing theory analysis at low agonist density.

    Science.gov (United States)

    Wedagedera, J R; Burroughs, N J

    2006-09-01

    We analyze a simple linear triggering model of the T-cell receptor (TCR) within the framework of queuing theory, in which TCRs enter the queue upon full activation and exit by downregulation. We fit our model to four experimentally characterized threshold activation criteria and analyze their specificity and sensitivity: the initial calcium spike, cytotoxicity, immunological synapse formation, and cytokine secretion. Specificity characteristics improve as the time window for detection increases, saturating for time periods on the timescale of downregulation; thus, the calcium spike (30 s) has low specificity but a sensitivity to single-peptide MHC ligands, while the cytokine threshold (1 h) can distinguish ligands with a 30% variation in the complex lifetime. However, a robustness analysis shows that these properties are degraded when the queue parameters are subject to variation-for example, under stochasticity in the ligand number in the cell-cell interface and population variation in the cellular threshold. A time integration of the queue over a period of hours is shown to be able to control parameter noise efficiently for realistic parameter values when integrated over sufficiently long time periods (hours), the discrimination characteristics being determined by the TCR signal cascade kinetics (a kinetic proofreading scheme). Therefore, through a combination of thresholds and signal integration, a T cell can be responsive to low ligand density and specific to agonist quality. We suggest that multiple threshold mechanisms are employed to establish the conditions for efficient signal integration, i.e., coordinate the formation of a stable contact interface.

  7. Effects of diversity and procrastination in priority queuing theory: the different power law regimes.

    Science.gov (United States)

    Saichev, A; Sornette, D

    2010-01-01

    Empirical analyses show that after the update of a browser, or the publication of the vulnerability of a software, or the discovery of a cyber worm, the fraction of computers still using the older browser or software version, or not yet patched, or exhibiting worm activity decays as a power law approximately 1/t(alpha) with 0queuing theory, of a target task which has the lowest priority compared to all other tasks that flow on the computer of an individual. We identify a "time deficit" control parameter beta and a bifurcation to a regime where there is a nonzero probability for the target task to never be completed. The distribution of waiting time T until the completion of the target task has the power law tail approximately 1/t(1/2), resulting from a first-passage solution of an equivalent Wiener process. Taking into account a diversity of time deficit parameters in a population of individuals, the power law tail is changed into 1/t(alpha), with alpha is an element of (0.5,infinity), including the well-known case 1/t. We also study the effect of "procrastination," defined as the situation in which the target task may be postponed or delayed even after the individual has solved all other pending tasks. This regime provides an explanation for even slower apparent decay and longer persistence.

  8. A Transient Queuing Model for Analyzing and Optimizing Gate Congestion of Railway Container Terminals

    Directory of Open Access Journals (Sweden)

    Ming Zeng

    2014-01-01

    Full Text Available As the significant connection between the external and internal of the railway container terminal, the operation performance of the gate system plays an important role in the entire system. So the gate congestion will bring many losses to the railway container terminal, even the entire railway container freight system. In this paper, the queue length and the average waiting time of the railway container terminal gate system, as well as the optimal number of service channels during the different time period, are investigated. An M/Ek/n transient queuing model is developed based on the distribution of the arrival time interval and the service time; besides the transient solutions are acquired by the equally likely combinations (ELC heuristic method. Then the model is integrated into an optimization framework to obtain the optimal operation schemes. Finally, some computational experiments are conducted for model validation, sensitivity testing, and system optimization. Experimental results indicate that the model can provide the accurate reflection to the operation situation of the railway container terminal gate system, and the approach can yield the optimal number of service channels within the reasonable computation time.

  9. Design and development of cell queuing, processing, and scheduling modules for the iPOINT input-buffered ATM testbed

    Science.gov (United States)

    Duan, Haoran

    1997-12-01

    This dissertation presents the concepts, principles, performance, and implementation of input queuing and cell-scheduling modules for the Illinois Pulsar-based Optical INTerconnect (iPOINT) input-buffered Asynchronous Transfer Mode (ATM) testbed. Input queuing (IQ) ATM switches are well suited to meet the requirements of current and future ultra-broadband ATM networks. The IQ structure imposes minimum memory bandwidth requirements for cell buffering, tolerates bursty traffic, and utilizes memory efficiently for multicast traffic. The lack of efficient cell queuing and scheduling solutions has been a major barrier to build high-performance, scalable IQ-based ATM switches. This dissertation proposes a new Three-Dimensional Queue (3DQ) and a novel Matrix Unit Cell Scheduler (MUCS) to remove this barrier. 3DQ uses a linked-list architecture based on Synchronous Random Access Memory (SRAM) to combine the individual advantages of per-virtual-circuit (per-VC) queuing, priority queuing, and N-destination queuing. It avoids Head of Line (HOL) blocking and provides per-VC Quality of Service (QoS) enforcement mechanisms. Computer simulation results verify the QoS capabilities of 3DQ. For multicast traffic, 3DQ provides efficient usage of cell buffering memory by storing multicast cells only once. Further, the multicast mechanism of 3DQ prevents a congested destination port from blocking other less- loaded ports. The 3DQ principle has been prototyped in the Illinois Input Queue (iiQueue) module. Using Field Programmable Gate Array (FPGA) devices, SRAM modules, and integrated on a Printed Circuit Board (PCB), iiQueue can process incoming traffic at 800 Mb/s. Using faster circuit technology, the same design is expected to operate at the OC-48 rate (2.5 Gb/s). MUCS resolves the output contention by evaluating the weight index of each candidate and selecting the heaviest. It achieves near-optimal scheduling and has a very short response time. The algorithm originates from a

  10. Study about simulation of supermarket queuing system%超市排队系统仿真研究

    Institute of Scientific and Technical Information of China (English)

    张琦琮; 杨公平; 张福强

    2011-01-01

    针对超市顾客等候过久问题,基于Agent范型,建立了顾客排队系统仿真模型.将顾客、收银台抽象为不同的Agent,并引入收银台管理Agent和引导员Agent.通过不同Agent之间的交互仿真超市排队系统的运行.模型中给出了一种收银台快速结算动态调整算法.实验数据和分析显示,该模型不仅可以真实地模拟超市排队系统运行现象,而且减少了顾客平均等待时间,降低了超市运营成本.%For the problem of the wait time of customers being too long in supermarkets, based on the agent paradigm, a simulation model of supermarket queuing system is established.The customers and check-outs are abstracted as different agents.Guide agent and check-out management agent are also introduced.The interaction among agents simulates the situation of supermarket queuing system.In the model a fast-track checkout scheduling algorithm based on dynamic adjustment is pro-posed.The experimental result and analysis show that the system not only can simulate the situation of supermarket queuing system actually,but also reduces the waiting time of customers and the operating costs of supermarket.

  11. Guanosine tetraphosphate as a global regulator of bacterial RNA synthesis: a model involving RNA polymerase pausing and queuing.

    Science.gov (United States)

    Bremer, H; Ehrenberg, M

    1995-05-17

    A recently reported comparison of stable RNA (rRNA, tRNA) and mRNA synthesis rates in ppGpp-synthesizing and ppGpp-deficient (delta relA delta spoT) bacteria has suggested that ppGpp inhibits transcription initiation from stable RNA promoters, as well as synthesis of (bulk) mRNA. Inhibition of stable RNA synthesis occurs mainly during slow growth of bacteria when cytoplasmic levels of ppGpp are high. In contrast, inhibition of mRNA occurs mainly during fast growth when ppGpp levels are low, and it is associated with a partial inactivation of RNA polymerase. To explain these observations it has been proposed that ppGpp causes transcriptional pausing and queuing during the synthesis of mRNA. Polymerase queuing requires high rates of transcription initiation in addition to polymerase pausing, and therefore high concentrations of free RNA polymerase. These conditions are found in fast growing bacteria. Furthermore, the RNA polymerase queues lead to a promoter blocking when RNA polymerase molecules stack up from the pause site back to the (mRNA) promoter. This occurs most frequently at pause sites close to the promoter. Blocking of mRNA promoters diverts RNA polymerase to stable RNA promoters. In this manner ppGpp could indirectly stimulate synthesis of stable RNA at high growth rates. In the present work a mathematical analysis, based on the theory of queuing, is presented and applied to the global control of transcription in bacteria. This model predicts the in vivo distribution of RNA polymerase over stable RNA and mRNA genes for both ppGpp-synthesizing and ppGpp-deficient bacteria in response to different environmental conditions. It also shows how small changes in basal ppGpp concentrations can produce large changes in the rate of stable RNA synthesis.

  12. Experimental Energy Consumption of Frame Slotted ALOHA and Distributed Queuing for Data Collection Scenarios

    Directory of Open Access Journals (Sweden)

    Pere Tuset-Peiro

    2014-07-01

    Full Text Available Data collection is a key scenario for the Internet of Things because it enables gathering sensor data from distributed nodes that use low-power and long-range wireless technologies to communicate in a single-hop approach. In this kind of scenario, the network is composed of one coordinator that covers a particular area and a large number of nodes, typically hundreds or thousands, that transmit data to the coordinator upon request. Considering this scenario, in this paper we experimentally validate the energy consumption of two Medium Access Control (MAC protocols, Frame Slotted ALOHA (FSA and Distributed Queuing (DQ. We model both protocols as a state machine and conduct experiments to measure the average energy consumption in each state and the average number of times that a node has to be in each state in order to transmit a data packet to the coordinator. The results show that FSA is more energy efficient than DQ if the number of nodes is known a priori because the number of slots per frame can be adjusted accordingly. However, in such scenarios the number of nodes cannot be easily anticipated, leading to additional packet collisions and a higher energy consumption due to retransmissions. Contrarily, DQ does not require to know the number of nodes in advance because it is able to efficiently construct an ad hoc network schedule for each collection round. This kind of a schedule ensures that there are no packet collisions during data transmission, thus leading to an energy consumption reduction above 10% compared to FSA.

  13. Impact of Mandatory HIV Screening in the Emergency Department: A Queuing Study.

    Science.gov (United States)

    Liu, Nan; Stone, Patricia W; Schnall, Rebecca

    2016-04-01

    To improve HIV screening rates, New York State in 2010 mandated that all persons 13-64 years receiving health care services, including care in emergency departments (EDs), be offered HIV testing. Little attention has been paid to the effect of screening on patient flow. Time-stamped ED visit data from patients eligible for HIV screening, 7,844 of whom were seen by providers and 767 who left before being seen by providers, were retrieved from electronic health records in one adult ED. During day shifts, 10% of patients left without being seen, and during evening shifts, 5% left without being seen. All patients seen by providers were offered testing, and 6% were tested for HIV. Queuing models were developed to evaluate the effect of HIV screening on ED length of stay, patient waiting time, and rate of leaving without being seen. Base case analysis was conducted using actual testing rates, and sensitivity analyses were conducted to evaluate the impact of increasing the testing rate. Length of ED stay of patients who received HIV tests was 24 minutes longer on day shifts and 104 minutes longer on evening shifts than for patients not tested for HIV. Increases in HIV testing rate were estimated to increase waiting time for all patients, including those who left without being seen. Our simulation suggested that incorporating HIV testing into ED patient visits not only adds to practitioner workload but also increases patient waiting time significantly during busy shifts, which may increase the rate of leaving without being seen. © 2016 Wiley Periodicals, Inc.

  14. Neural Network Based Scheduling for Variable-Length Packets in Gigabit Router with Crossbar Switch Fabric and Input Queuing

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A high-speed and effective packet scheduling method is crucial to the performance of Gigabit routers. The paper studies the variable-length packet scheduling problem in Gigabit router with crossbar switch fabric and input queuing, and a scheduling method based on neural network is proposed. For the proposed method, a scheduling system structure fit for the variable-length packet case is presented first, then some rules for scheduling are given, At last, an optimal scheduling method using Hopfield neural network is proposed based on the rules. Furthermore, the paper discusses that the proposed method can be realized by hardware circuit. The simulation result shows the effectiveness of the proposed method.

  15. Non-Stationary Single-Channel Queuing System Features Research in Context of Number of Served Queries

    Directory of Open Access Journals (Sweden)

    Porshnev Sergey

    2017-01-01

    Full Text Available This work devoted to researching of mathematical model of non-stationary queuing system (NQS. Arrival rate in studied NQS λ(t is similar to rate which observed in practice in a real access control system of objects of mass events. Dependence of number of serviced requests from time was calculated. It is proven that the ratio value of served requests at the beginning of event to all served requests described by a deterministic function, depending on the average service rate μ¯$\\bar \\mu $ and the maximum value of the arrival rate function λ(t.

  16. Out-of-Sequence Preventative Cell Dispatching for Multicast Input-Queued Space-Memory-Memory Clos-Network

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    This paper proposes two out-of-sequence (OOS) preventative cell dispatching algorithms for the multicast input-queued space-memory-memory (IQ-SMM) Clos-network switch architecture, i.e. the multicast flow-based DSRR (MF-DSRR) and the multicast flow-based round-robin (MFRR). Treating each cell...... independently, the desynchronized static round-robin (DSRR) cell dispatching scheme can evenly distribute cells to the central switching modules, however, its frequent change of the input switching module connection pattern causes a serious OOS problem to the IQ-SMM architecture. Therefore large reassembly...

  17. Preventing Out-of-Sequence for Multicast Input-Queued Space-Memory-Memory Clos-Network

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    This paper proposes an out-of-sequence (OOS) preventative cell dispatching algorithm, the multicast flow-based round robin (MFRR), for multicast input-queued space-memory-memory (IQ-SMM) Clos-network architecture. Independently treating each incoming cell, such as the desynchronized static round...... robin (DSRR), can lead to cells of the same packet being disordered after traversing the switch fabric. Extra reassembly buffer and delay are thus required at the outputs of the switch fabric to reorder the cells. Simulation results obtained by OPNET Modeler show that the MFRR can eliminate such OOS...

  18. Pay Great Attention to the "Material Queuing"%不可忽视的“物料等待”

    Institute of Scientific and Technical Information of China (English)

    徐丽霞

    2012-01-01

    In this low-profit time, we to analyze the material feature and to have the "ma demonstrate th terial queuing" everywhere in the company. This article is e importance of the material management. Then it lists and explains the several important factors of material management. The intention of this article is to bring the at- tention of the company management team to this important issue, to improve the performance on material man- agement and fine management, reduce the material queuing and the product cost, which is the very importance factor of a company's operation quality and competitive power%面对当今微利社会,企业随处可见的“物料等待”状况。通过对物料特的行分析,可知物料是需要管理的。企业应该引起重视,加强物料管理,以使管理精细化,改善“物料等待”状况,消除“物料等待”的浪费,降低产品成本,提高企业的营运质量和竞争能力。

  19. CROSS-LAYER RESOURCE SCHEDULING WITH QOS GUARANTEES USING ADAPTIVE TOKEN BANK FAIR QUEUING ALGORITHM IN WIRELESS NETWORKS

    Directory of Open Access Journals (Sweden)

    G. INDUMATHI

    2011-06-01

    Full Text Available Orthogonal Frequency Division Multiplexing (OFDM systems are the major cellular platforms for supporting ubiquitous high-speed mobile applications. However, a number of research challenges remain to be tackled. One of the most important challenges is the design of a judicious packet scheduler that will make efficient use of the spectrum bandwidth. Due to the multicarrier nature of the OFDM systems, the applicability and performance of traditional wireless packet scheduling algorithms, which are designed usually for single-carrier systems, are largely unknown. In this paper we present a new scheduler which includes packet scheduling and resource mapping which takes. The proposed algorithm is based on a cross-layer design in that the scheduler is aware of both the channel at the physical layer and the queue state at the data link layer information to achieve proportional fairness while maximizing each user’s packet level QoS performance. The performance of the proposed work is compared to that of the round-robin and weighted fair queuing schedulers. It is observed that from the simulation that the proposed scheduling with adaptive parameter selection provides enhanced performance in terms of queuing delay and spectral efficiency. Also we analyze the achieved fairness of the schemes in terms of different fairness indices available in literature.

  20. Modeling and Analysis of Queuing Systems in Banks A case study of Ghana Commercial Bank Ltd. Kumasi Main Branch

    Directory of Open Access Journals (Sweden)

    Wallace Agyei

    2015-07-01

    Full Text Available Abstract Queues are common sight of many banks in Ghana. The obvious implication of customers waiting in long and winding queues could result to prolonged discomfort and economic cost to them however increasing the service rate will require additional number of tellers which implies extra cost to management. This study therefore attempts to find the trade-off between minimizing the total economic cost waiting cost and service cost and the provision of a satisfactory and reasonably shortest possible time of service to customers in order to assist management of the bank in deciding the optimal number of tellers needed. Data for this study was collected at the Ghana Commercial Bank Ltd Kumasi Main Branch for one month through observations interviews and by administering of questionnaire and was formulated as multi-server single line queuing model. The data was analyzed using TORA optimization Software as well as using descriptive method of analysis. The performance measures of different queuing systems were evaluated and analyzed. The results of the analysis showed using a five teller system was better than a four or a six-teller system in terms of average waiting time and thetotal economic cost hence the study recommends that the management should adopt a five teller model to reduce total economic costs and increase customer satisfaction.

  1. Using queuing theory to analyse the government's 4-H completion time target in accident and emergency departments.

    Science.gov (United States)

    Mayhew, L; Smith, D

    2008-03-01

    This paper uses a queuing model to evaluate completion times in Accident and Emergency (A&E) departments in the light of the Government target of completing and discharging 98% of patients inside 4 h. It illustrates how flows though an A&E can be accurately represented as a queuing process, how outputs can be used to visualise and interpret the 4-h Government target in a simple way and how the model can be used to assess the practical achievability of A&E targets in the future. The paper finds that A&E targets have resulted in significant improvements in completion times and thus deal with a major source of complaint by users of the National Health Service in the U.K. It suggests that whilst some of this improvement is attributable to better management, some is also due to the way some patients in A&E are designated and therefore counted through the system. It finds for example that the current target would not have been possible without some form of patient re-designation or re-labelling taking place. Further it finds that the current target is so demanding that the integrity of reported performance is open to question. Related incentives and demand management issues resulting from the target are also briefly discussed.

  2. Queuing for Union Jobs and the Social Return to Schooling. Institute for Research on Poverty Discussion Papers. Report 360-76.

    Science.gov (United States)

    Bishop, John

    An analysis of the argument that a market imperfection (wage differentials and queuing caused by unions) raises the marginal social product (MSP) of college education above the average before-tax private wage premium (APP) for college (this discrepancy is called a union-Q-nality) focuses on verifying five hypotheses: (1) Workers with identical…

  3. Modeling Relief Demands in an Emergency Supply Chain System under Large-Scale Disasters Based on a Queuing Network

    Science.gov (United States)

    He, Xinhua

    2014-01-01

    This paper presents a multiple-rescue model for an emergency supply chain system under uncertainties in large-scale affected area of disasters. The proposed methodology takes into consideration that the rescue demands caused by a large-scale disaster are scattered in several locations; the servers are arranged in multiple echelons (resource depots, distribution centers, and rescue center sites) located in different places but are coordinated within one emergency supply chain system; depending on the types of rescue demands, one or more distinct servers dispatch emergency resources in different vehicle routes, and emergency rescue services queue in multiple rescue-demand locations. This emergency system is modeled as a minimal queuing response time model of location and allocation. A solution to this complex mathematical problem is developed based on genetic algorithm. Finally, a case study of an emergency supply chain system operating in Shanghai is discussed. The results demonstrate the robustness and applicability of the proposed model. PMID:24688367

  4. Modeling relief demands in an emergency supply chain system under large-scale disasters based on a queuing network.

    Science.gov (United States)

    He, Xinhua; Hu, Wenfa

    2014-01-01

    This paper presents a multiple-rescue model for an emergency supply chain system under uncertainties in large-scale affected area of disasters. The proposed methodology takes into consideration that the rescue demands caused by a large-scale disaster are scattered in several locations; the servers are arranged in multiple echelons (resource depots, distribution centers, and rescue center sites) located in different places but are coordinated within one emergency supply chain system; depending on the types of rescue demands, one or more distinct servers dispatch emergency resources in different vehicle routes, and emergency rescue services queue in multiple rescue-demand locations. This emergency system is modeled as a minimal queuing response time model of location and allocation. A solution to this complex mathematical problem is developed based on genetic algorithm. Finally, a case study of an emergency supply chain system operating in Shanghai is discussed. The results demonstrate the robustness and applicability of the proposed model.

  5. Enhanced first-in-first-out-based round-robin multicast scheduling algorithm for input-queued switches

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    This study focuses on the multicast scheduling for M × N input-queued switches. An enhanced first-in-first-out -based round-robin multicast scheduling algorithm is proposed with a function of searching deeper into queues to reduce the head-of-line (HOL) blocking problem and thereby the multicast...... out on the decision matrix to reduce the number of transmission for each cell. To reduce the HOL blocking problem, a complement matrix is constructed based on the traffic matrix and the decision matrix, and a process of searching deeper into the queues is carried out to find cells that can be sent...... to the idle outputs. Simulation results show that the proposed function of searching deeper into the queues can alleviate the HOL blocking and as a result reduce the multicast latency significantly. Under both balanced and unbalanced multicast traffic, the proposed algorithm is able to maintain a stable...

  6. Modeling Relief Demands in an Emergency Supply Chain System under Large-Scale Disasters Based on a Queuing Network

    Directory of Open Access Journals (Sweden)

    Xinhua He

    2014-01-01

    Full Text Available This paper presents a multiple-rescue model for an emergency supply chain system under uncertainties in large-scale affected area of disasters. The proposed methodology takes into consideration that the rescue demands caused by a large-scale disaster are scattered in several locations; the servers are arranged in multiple echelons (resource depots, distribution centers, and rescue center sites located in different places but are coordinated within one emergency supply chain system; depending on the types of rescue demands, one or more distinct servers dispatch emergency resources in different vehicle routes, and emergency rescue services queue in multiple rescue-demand locations. This emergency system is modeled as a minimal queuing response time model of location and allocation. A solution to this complex mathematical problem is developed based on genetic algorithm. Finally, a case study of an emergency supply chain system operating in Shanghai is discussed. The results demonstrate the robustness and applicability of the proposed model.

  7. Prior individual training and self-organized queuing during group emergency escape of mice from water pool.

    Directory of Open Access Journals (Sweden)

    Caesar Saloma

    Full Text Available We study the impact of prior individual training during group emergency evacuation using mice that escape from an enclosed water pool to a dry platform via any of two possible exits. Experimenting with mice avoids serious ethical and legal issues that arise when dealing with unwitting human participants while minimizing concerns regarding the reliability of results obtained from simulated experiments using 'actors'. First, mice were trained separately and their individual escape times measured over several trials. Mice learned quickly to swim towards an exit-they achieved their fastest escape times within the first four trials. The trained mice were then placed together in the pool and allowed to escape. No two mice were permitted in the pool beforehand and only one could pass through an exit opening at any given time. At first trial, groups of trained mice escaped seven and five times faster than their corresponding control groups of untrained mice at pool occupancy rate ρ of 11.9% and 4%, respectively. Faster evacuation happened because trained mice: (a had better recognition of the available pool space and took shorter escape routes to an exit, (b were less likely to form arches that blocked an exit opening, and (c utilized the two exits efficiently without preference. Trained groups achieved continuous egress without an apparent leader-coordinator (self-organized queuing-a collective behavior not experienced during individual training. Queuing was unobserved in untrained groups where mice were prone to wall seeking, aimless swimming and/or blind copying that produced circuitous escape routes, biased exit use and clogging. The experiments also reveal that faster and less costly group training at ρ = 4%, yielded an average individual escape time that is comparable with individualized training. However, group training in a more crowded pool (ρ = 11.9% produced a longer average individual escape time.

  8. Analysis of Quality of Service Performances of Connection Admission Control Mechanisms in OFDMA IEEE 802.16 Network using BMAP Queuing

    CERN Document Server

    Bouchti, Abdelali El; Kafhali, Said El

    2012-01-01

    In this paper, we consider a single-cell IEEE 802.16 environment in which the base station allocates subchannels to the subscriber stations in its coverage area. The subchannels allocated to a subscriber station are shared by multiple connections at that subscriber station. To ensure the Quality of Service (QoS) performances, two Connection Admission Control (CAC) mechanisms, namely, threshold-based and queue-aware CAC mechanisms are considered at a subscriber station. A queuing analytical framework for these admission control mechanisms is presented considering Orthogonal Frequency Division Multiple Access (OFDMA) based transmission at the physical layer. Then, based on the queuing model, both the connection-level and the packet-level performances are studied and compared with their analogues in the case without CAC. The connection arrival is modeled by a Poisson process and the packet arrival for a connection by Batch Markov Arrival Process (BMAP). We determine analytically and numerically different QoS per...

  9. Mathematically modelling the effects of pacing, finger strategies and urgency on numerical typing performance with queuing network model human processor.

    Science.gov (United States)

    Lin, Cheng-Jhe; Wu, Changxu

    2012-01-01

    Numerical typing is an important perceptual-motor task whose performance may vary with different pacing, finger strategies and urgency of situations. Queuing network-model human processor (QN-MHP), a computational architecture, allows performance of perceptual-motor tasks to be modelled mathematically. The current study enhanced QN-MHP with a top-down control mechanism, a close-loop movement control and a finger-related motor control mechanism to account for task interference, endpoint reduction, and force deficit, respectively. The model also incorporated neuromotor noise theory to quantify endpoint variability in typing. The model predictions of typing speed and accuracy were validated with Lin and Wu's (2011) experimental results. The resultant root-mean-squared errors were 3.68% with a correlation of 95.55% for response time, and 35.10% with a correlation of 96.52% for typing accuracy. The model can be applied to provide optimal speech rates for voice synthesis and keyboard designs in different numerical typing situations. An enhanced QN-MHP model was proposed in the study to mathematically account for the effects of pacing, finger strategies and internalised urgency on numerical typing performance. The model can be used to provide optimal pacing for voice synthesise systems and suggested optimal numerical keyboard designs under urgency.

  10. Queuing theory under competitive social foraging may explain a mathematical equivalence of delay and probability in impulsive decision-making.

    Science.gov (United States)

    Takahashi, Taiki

    2006-01-01

    Intertemporal and probabilistic decision-making has been studied in psychiatry, ecology, and neuroeconomics. Because drug addicts and psycopaths often make risky decisions (e.g., drug misuse and aggression), investigation into types of impulsivity in intertemporal and probabilistic choices (delay and probability discounting) are important for psychiatric treatments. Studies in behavioral ecology proposed that delay and probability discounting are mediated by the same psychological process, because a decrease in probability of winning corresponds to an increase in delay until winning. According to this view, odds-against winning (=1/p-1) in probabilistic choice corresponds to delay in intertemporal choice. This hypothesis predicts that preference of gambling (low degree of probability discounting) may be associated with patience, rather than impulsivity or impatience, in intertemporal choice (low degree of delay discounting). However, recent empirical evidence in psychiatric research employing pathological gamblers indicates that pathological gamblers are impulsive in intertemporal choice (high degrees of delay discounting). However, a hyperbolic discounting function (usually adopted to explain intertemporal choice) with odds-against (instead of delay) explain experimental data in probabilistic choice dramatically well. Therefore, an alternative explanation is required for the hypothetical equivalence of odds-against to delay. We propose that queuing theory (often adopted for analyzing computer network traffic) under a competitive social foraging condition may explain the equivalence. Our hypothesis may help understand impulsivity of psychiatrics in social behavior (e.g., aggression and antisocial behavior) in addition to non-social impulsivity in reward-seeking (e.g., substance misuse).

  11. To Minimize the Waiting Time and Waiting Time Cost of Dumpers, Waiting in a Queue for Loader at Stone Crusher Plant Mine by Using the Single and Multi-Channel Queuing Theory.

    Directory of Open Access Journals (Sweden)

    Vaibhav Singh

    2014-09-01

    Full Text Available Waiting line problems arise because there is too much demand on the facilities so that we can say that there is an excess of waiting time or inadequate number of service facilities. At the stone crusher plant mine the dumpers come to load from the loader. The crusher plant has 11 dumpers and these 11 dumpers make 88 trips during 8-hour day. The company has one loader to load all the dumpers, which results in a formation of long waiting line or queue. Due to this queue there is a long waiting time in queue of dumpers and cost associated with waiting time of dumpers. Queuing theory can quite effectively analyze such queuing phenomenon. In this research paper I have applied the queuing theory to the stone crusher plant mine, where the queue of dumpers formed at the loading station. By applying the single channel queuing theory I analyzed the current situation of the stone crusher plant mine and find the problems of the current system. To overcome the above problems I have applied the multi-channel queuing theory to minimize the waiting time in queue of dumpers and very high cost associated with waiting time of dumpers. In the new system not only waiting time in queue of dumpers and very high cost associated with waiting time of dumpers is reduced but also there is an efficient utilization of dumpers and loaders along with provide the profitable situation to the crusher plant.

  12. Energy-Efficiency Analysis of a Distributed Queuing Medium Access Control Protocol for Biomedical Wireless Sensor Networks in Saturation Conditions

    Directory of Open Access Journals (Sweden)

    Christos Verikoukis

    2011-01-01

    Full Text Available The aging population and the high quality of life expectations in our society lead to the need of more efficient and affordable healthcare solutions. For this reason, this paper aims for the optimization of Medium Access Control (MAC protocols for biomedical wireless sensor networks or wireless Body Sensor Networks (BSNs. The hereby presented schemes always have in mind the efficient management of channel resources and the overall minimization of sensors’ energy consumption in order to prolong sensors’ battery life. The fact that the IEEE 802.15.4 MAC does not fully satisfy BSN requirements highlights the need for the design of new scalable MAC solutions, which guarantee low-power consumption to the maximum number of body sensors in high density areas (i.e., in saturation conditions. In order to emphasize IEEE 802.15.4 MAC limitations, this article presents a detailed overview of this de facto standard for Wireless Sensor Networks (WSNs, which serves as a link for the introduction and initial description of our here proposed Distributed Queuing (DQ MAC protocol for BSN scenarios. Within this framework, an extensive DQ MAC energy-consumption analysis in saturation conditions is presented to be able to evaluate its performance in relation to IEEE 802.5.4 MAC in highly dense BSNs. The obtained results show that the proposed scheme outperforms IEEE 802.15.4 MAC in average energy consumption per information bit, thus providing a better overall performance that scales appropriately to BSNs under high traffic conditions. These benefits are obtained by eliminating back-off periods and collisions in data packet transmissions, while minimizing the control overhead.

  13. Energy-efficiency analysis of a distributed queuing medium access control protocol for biomedical wireless sensor networks in saturation conditions.

    Science.gov (United States)

    Otal, Begonya; Alonso, Luis; Verikoukis, Christos

    2011-01-01

    The aging population and the high quality of life expectations in our society lead to the need of more efficient and affordable healthcare solutions. For this reason, this paper aims for the optimization of Medium Access Control (MAC) protocols for biomedical wireless sensor networks or wireless Body Sensor Networks (BSNs). The hereby presented schemes always have in mind the efficient management of channel resources and the overall minimization of sensors' energy consumption in order to prolong sensors' battery life. The fact that the IEEE 802.15.4 MAC does not fully satisfy BSN requirements highlights the need for the design of new scalable MAC solutions, which guarantee low-power consumption to the maximum number of body sensors in high density areas (i.e., in saturation conditions). In order to emphasize IEEE 802.15.4 MAC limitations, this article presents a detailed overview of this de facto standard for Wireless Sensor Networks (WSNs), which serves as a link for the introduction and initial description of our here proposed Distributed Queuing (DQ) MAC protocol for BSN scenarios. Within this framework, an extensive DQ MAC energy-consumption analysis in saturation conditions is presented to be able to evaluate its performance in relation to IEEE 802.5.4 MAC in highly dense BSNs. The obtained results show that the proposed scheme outperforms IEEE 802.15.4 MAC in average energy consumption per information bit, thus providing a better overall performance that scales appropriately to BSNs under high traffic conditions. These benefits are obtained by eliminating back-off periods and collisions in data packet transmissions, while minimizing the control overhead.

  14. M|M|c| Queuing Model and Its Application in the Supermarket Management%M|M|c|∞排队模型及其在超市管理中的应用

    Institute of Scientific and Technical Information of China (English)

    王丙参; 李玉玲; 魏艳华

    2012-01-01

    The paper studies the supermarket queuing system by using Random dynamic theory, establishes queuing mode and obtains the supermarket queue indexes by testing Poisson distribution with spss software which can provide reference for the supermarket management.%文章采用随机动态理论对超市排队系统进行研究,建立了M|M|c|∞模型,用spss软件对客流量进行泊松检验,得到了超市的一些排队指标,对超市的人员管理具有一定的参考价值.

  15. Green supply chain management using the queuing theory to handle congestion and reduce energy consumption and emissions from supply chain transportation fleet

    Directory of Open Access Journals (Sweden)

    Arvin Aziziankohan

    2017-05-01

    Full Text Available Purpose: Nowadays, governments and people pay more attention to use green products due to environmental pollution, irreplaceable energy and shortage of resources. Green products are resulted from the application of green supply chain management strategies to the organizations' performance strategies, so that we can reduce environmental pollutants and wastes and take a step towards saving energy with limited resources. Methodology:  In this paper, the effect of reducing energy consumption in green supply chain is examined by using queuing theory and transportation models. Data was generated and solved by a commercial optimization epackage. Findings:  The findings indicate that suitable assignment of existing transportation fleet with specified capacity, and using queueing theory in a closed-loop network to reduce the queue length and handle congestion, can cause a reduction in energy consumption by optimizing transportation and waiting times in a green supply chain. Originality/value: Adopting investment strategy in improving the environmental performance of the supply chain, will yield in many advantages and benefits. This article investigates the effect of queuing theory on reducing waiting time, optimizing energy consumption in green supply chain, and consequently decreasing pollution.

  16. Development of Markov Chain-Based Queuing Model and Wireless Infrastructure for EV to Smart Meter Communication in V2G

    Science.gov (United States)

    Santoshkumar; Udaykumar, R. Y.

    2015-04-01

    The electrical vehicles (EVs) can be connected to the grid for power transaction. The vehicle-to-grid (V2G) supports the grid requirements and helps in maintaining the load demands. The grid control center (GCC), aggregator and EV are three key entities in V2G communication. The GCC sends the information about power requirements to the aggregator. The aggregator after receiving the information from the GCC sends the information to the EVs. Based on the information, the interested EV owners participate in power transaction with the grid. The aggregator facilitates the EVs by providing the parking and charging slot. In this paper the queuing model for EVs connected to the grid and development of wireless infrastructure for the EV to Smart Meter communication is proposed. The queuing model is developed and simulated. The path loss models for WiMAX are analyzed and compared. Also, the physical layer of WiMAX protocol is modeled and simulated for the EV to Smart Meter communication in V2G.

  17. On a Batch Arrival Queuing System Equipped with a Stand-by Server during Vacation Periods or the Repairs Times of the Main Server

    Directory of Open Access Journals (Sweden)

    Rehab F. Khalaf

    2011-01-01

    Full Text Available We study a queuing system which is equipped with a stand-by server in addition to the main server. The stand-by server provides service to customers only during the period of absence of the main server when either the main server is on a vacation or it is in the state of repairs due to a sudden failure from time to time. The service times, vacation times, and repair times are assumed to follow general arbitrary distributions while the stand-by service times follow exponential distribution. Supplementary variables technique has been used to obtain steady state results in explicit and closed form in terms of the probability generating functions for the number of customers in the queue, the average number of customers, and the average waiting time in the queue while the MathCad software has been used to illustrate the numerical results in this work.

  18. Effectiveness Evaluation of Air Defense System Based on Queuing Theory%基于排队论的防空作战效能评估

    Institute of Scientific and Technical Information of China (English)

    高志华; 唐金国; 文建国; 李木易; 刘志豪; 王雷

    2012-01-01

    文章分析了防空体系对空袭目标的拦截次数计算方法,通过排队论的方法,建立了防空体系效能评估模型。最后通过仿真计算,得出影响防空体系作战效能的重要因素,为决策提供一定的理论依据。%This text analyzes the computing technology of intercepting numbers of air defense system to the goal. Through the queuing theory method, have set up the evaluation efficiency model of air defense system. Finally simulation results show the important factors of in- fluencing the fighting efficiency of air defense system, and offer certain theoretical foundation for people who making policy.

  19. Implementacija metode automatizovanih nezavisnih ponavljanja u simulaciji sistema masovnog opsluživanja / Implementation of automated independent replications in the simulation of queuing systems

    Directory of Open Access Journals (Sweden)

    Nebojša V. Nikolić

    2010-10-01

    Full Text Available U radu je opisana osnovna ideja metode pod nazivom 'Automatizovano ponavljanje nezavisnih simulacionih eksperimenata sa prikupljanjem statistike slučajnih procesa'. Data je matematička osnova metode i prikazane su preporuke za implementaciju metode u formu algoritma za računarski program. Pregledno su istaknuta potrebna ekspertska znanja za uspešan razvoj konceptualnih i simulacionih modela. Metoda je testirana u istraživanju sistema masovnog opsluživanja. / This paper presents a basic idea of the method entitled 'Automated Independent Replications with Gathering Statistics of Stochastic Processes'. The mathematical foundation of the method is offered, as well as some recommendations for practical implementation of the met hod in the form of a computer program algorithm. A set of different expert knowledge needed for a successful development of conceptual and simulation models is pointed out in a separate review. The method has been tested in the modeling and simulation of queuing systems. Multidisciplinary character of simulation modeling This paper presents a basic idea of the method entitled 'Automated Independent Replications with Gathering Statistics of Stochastic Processes'. A clear review of expert knowledge needed for successful development of a conceptual model as well as a simulation one is offered. Simulation modeling of systems and processes in any military branch assumes a multidisciplinary approach. This is not a consequence of a free choice, but of needs and problems which arise in a research process and which require synchronized use of knowledge from different areas and scientific disciplines. In studies of queuing systems, these disciplines are: queuing theory, probability theory, mathematical statistics, stochastic processes, mathematical analyses, Monte Carlo simulation modeling, computer programming, knowledge about a real system under study, etc. Specific features of real queuing systems Consistency, fidelity or

  20. Simulation of M/M/m Queuing Model Based on Markov State Transition Process%基于马尔科夫状态转移过程的M/M/m排队模型仿真

    Institute of Scientific and Technical Information of China (English)

    曹永荣; 韩瑞霞; 胡伟

    2012-01-01

    马尔科夫链是研究排队系统的主要方法,本文在现有M/M/m排队理论和排队系统仿真理论基础上,利用Matlab建立基于马尔科夫状态转移过程的M/M/m排队模型仿真程序.仿真程序在产生初始化参数设定后,利用时钟推进法来模拟空闲服务台和繁忙服务台情况下的服务流程,最后通过M/M/m模型特征描述的仿真计算,获得平均等待时间(E[W])、平均停机时间(E[ DT])、平均排队队长E[ Q]、系统中的平均客户数(E[L])和可能延迟的概率((Ⅱ))5项重要的特征描述.模拟次数设定为20 000次,模拟客户服务率和客户到达率相同,服务台在3~6个的排队系统,并将仿真结果与理论值以及Queue2.0的模拟结果相比较.最终结果显示E[W]、[DT]和H3项最重要指标的仿真结果和理论值都极为相近,误差范围小,本研究将为优先权排队系统的仿真研究提供理论依据.%Markov chain is the main method for the study of queuing systems. This paper integrates the existing theories of M/M/m queuing system and theories of queuing system simulation, and builds simulation program of M/M/m Queuing Model according to the Markov state transition process using Matlab. The simulation process is as follows. First of all, simulation program initializes the parameter settings, such as service time, the interval of customer arrival, the number of server etc. Secondly, promotes the program used time clock which is based on the arrival time of customers and the end time of service. Thirdly, simulates the free servers and busy servers process when a customer arrived, and recodes the corresponding data. Finally, calculate the M/M/m model's characterized descriptions , included in the average down time (E[ DT] ) , the average waiting time (E[ W]), the average number of queuing customer (E[(Q])> the average number of customers in the queuing system( E[ L]) and delay probability (Ⅱ) , based on the simulation formula. Sets the

  1. Analysis and Design of Tobacco Sold Queuing System%烟叶交售排队系统的分析与设计

    Institute of Scientific and Technical Information of China (English)

    王智坚; 李水平; 包洋; 李金娟; 张莨

    2015-01-01

    介绍了烟叶交售排队系统的研究背景,对所需要解决的问题进行了概述;论文提出了系统的设计目标,对系统进行了详细的需求分析,包括业务需求分析、功能需求分析、数据需求分析;在系统设计中,对系统进行了总体设计与模块设计,详细阐述了设计内容,并使用实体关系E-R图和实体属性对数据库进行了详细设计。%This paper first introduces the research background of the tobacco sold queuing system and summarizes the problems need to be solved.It presents the system design goals of the system carried out a detailed needs analysis, including business require⁃ments analysis, functional requirements analysis, data requirements analysis;in the system design, the overall design of the system and module design were made to elaborate design content, and it makes detail design of the database for using the ER diagram and entity relationship structure.

  2. 一种基于WRR的新的调度算法%A New Queuing Scheduling Algorithm Based on Weighted Round Robin

    Institute of Scientific and Technical Information of China (English)

    饶宝乾; 侯嘉

    2011-01-01

    为了提高网络区分服务的性能,选择一个合适的队列调度算法尤为重要.在WRR调度算法的基础上提出了一种新的调度算法P-VDWRR(Priority Variable Deficit Weighted Round Robin),P-VDWRR不仅能够提供一定的QiS(Quality of Service)保证,还能够在一定范围内根据网络负载情况动态分配网络资源,降低网络节点的丢包率.%In order to improve the performance of distinguished network services, it is particularly important to select an appropriate queuing scheduling algorithm. A new scheduling algorithm is proposed based on the WRR,whose name is Priority Variable Deficit Weighted Round Robin(P-VDWRR). P-VDWRR could provide certain assurance of the QoS, distribute the network resources dynamically according to the load situation within a certain range and reduce the packet loss rate of network nodes.

  3. Weighted Fair Queuing and Feedback Round Robin Scheduling Algorithm on MPLmS%MPLmS中基于WFQ的轮转调度算法

    Institute of Scientific and Technical Information of China (English)

    周乃富

    2014-01-01

    分析了MPLmS网络的基本原理,为了能在标签的分配中更好地体现QoS,通过引入多协议标签交换(MPLS)流量工程控制技术与光交叉连接相结合的一种新型光互联技术--多协议波长标签交换(MPLmS),重点对标签的分配策略进行分析和设计,提出了一种新的基于WFQ轮转调度算法。%This paper analyzes the basic principles of the network MPLmS. in order to be able to better reflect the QoS of The distribution of the label. Through introducing Multi-Protocol lambda Switching which is a traffic engineering control technology on the Multi-Protocol Label Switching and the light cross connection unify, we focus on the label allocation strategy analysis and design. A new Weighted Fair Queuing and feedback round robin scheduling algorithm is proposed.

  4. 基于排队理论的汽车租赁运营策略%Queuing Theory-Based Operation Policies for Car Renting

    Institute of Scientific and Technical Information of China (English)

    王娟; 杨爱峰

    2011-01-01

    In car renting, customer demands rental time are subject to random variation. Thus, it is difficult to model and optimize such a process. The car renting is treated as a real-time queuing process. Based on this concept, for a car rental company, aiming at maximizing its profit by determiriing the number of vehicles needed,a mathematical model is developed. With this model, the profit obtained by two companies under cooperation is compared with that obtained without cooperation. Results show that more profit can be obtained with cooperation than without cooperation. Furthermore, based on the total profit increase for the two cooperative companies, the acceptable sublet price range ispresented. Thus, by using the proposed method,a car renting company can select its most profitable operation policy. Numerical examples are given to verify the proposed method.%将汽车租赁问题转化为即时排队系统M/M/n/n/∞模型,解决了在租赁模型中顾客需求与租期都是随机参数的难题.在租赁商独立经营的情况下,以利润最大化为目标建立模型,得到租赁商的最优车辆购置数;比较两家租赁商合作经营与独立经营情况下的利润,得出合作经营后总利润增加值与两租赁商均可以接受的转租价格,为租赁商选择有利的运营策略提供了理论依据;通过算例验证了模型的有效性.

  5. 基于排队论的配送策略研究%Research on Delivery Strategy Based on Queuing Theory

    Institute of Scientific and Technical Information of China (English)

    张伊彤; 赵刚

    2013-01-01

    In delivery problem,delivery vehicle is equivalent to the reception desk.The site waiting to be served is equivalent to the customer.To insure the requirement is considered in many aspects,the requirement is divided to two types:ordinary requirement and emergency requirement.For ordinary requirement,the paper uses AHP to consider the delivery sequence.For emergency requirement,uses one separate delivery car to serve.Using multi-reception desk mixed model to get the indicators of queuing theory.Compared with one sever mixed model,the effect is much better.%在配送问题中,配送车辆相当于服务台,等待被送货的地点相当于顾客。为保证配送请求被多方面考虑,将送货地点的请求分为“普通请求”和“紧急请求”,对于“普通请求”应用层次分析法确定配送次序,另外对于“紧急请求”采用单独配送车辆进行服务。应用多服务台混合制模型获得排队系统的各项指标,与单服务台模型进行各项指标对比,效果明显较好。

  6. 考虑公平与效率目标的城乡配送中心排队选址模型%The Queuing Location Models of Urban-rural Distribution Centers Considering Equity and Efficiency

    Institute of Scientific and Technical Information of China (English)

    曾倩; 张锦; 陈义友

    2016-01-01

    为解决随机需求下的城乡配送中心选址问题,实现物流服务的效率与公平,结合排队论构建了需求转移规则下的排队选址模型。为体现城乡客户需求特征差异,构建时间满意度函数作为服务水平的衡量指标。将客户与配送中心看作M/M/p排队系统,采用需求可转移的排队规则,运用超立方模型计算配送中心的可用概率。目标函数包括嫉妒最小、基尼系数最小及字典序最大等3类公平目标,以及覆盖需求量最大、满意度最大两类效率目标。设计禁忌搜索算法求解,通过算例对模型和算法进行验证。结果表明,P中位模型下效率最优,最小嫉妒目标下公平最优,而最大字典序目标可以兼顾公平与效率。%To solve the location problem of urban-rural distribution centers under the random demand condition, queuing location models are built combined with queuing theory under a demand transfer rule. And the models focus on both equity goals and efficiency goals. The time satisfaction functions as the measure of service level reflects the differences between urban and rural demands. The system of customers and distribution centers is considered to be an M/M/p queuing system. The queuing discipline allows demands transfer when the distribution center is busy. The hypercube model is provided to calculate the probability of centers being available. The objective functions include equity objectives such as minimizing envy, minimizing Gini coefficient and maximizing lexicographical order, and efficiency objectives such as maximizing demands covered and satisfaction. The models are solved by a tabu search algorithm and tested on a real world data set from the distribution system. It is proved that the P-median model is efficiency optimization; the minimize envy model is equity optimization; the maximize lexicographical order model can achieve the equity-efficiency tradeoff.

  7. 浅谈妇产科医院排队叫号系统的应用与发展%Application and Development of Obstetrics and Gynecology Hospital Queuing System

    Institute of Scientific and Technical Information of China (English)

    袁隆; 杨旋; 张梦杰

    2015-01-01

    医院排队叫号系统是近年来为改善医疗行业传统排队管理中存在的一些混乱、无序和不文明等弊端而开发的。本文从需求出发,介绍并讨论了医院排队叫号系统的实施与在医院内的应用与发展前景。%The hospital queuing system is developed in recent years to improve the medical industry traditional queue management in some confusion.The system can wel solve a variety of patients encountered in the doctor process queue,waiting and congestion management,to see patients and hospital to bring great convenience and delight.In this paper,we introduces and discusses the prospect of application and development of the implementation of hospital queuing system and in the hospital.

  8. Well-Posedness of M/G/1 Queuing System with Multiple Working Vacation and Vacation Interruption%工作休假和休假中止的M/G/1排队模型的适定性

    Institute of Scientific and Technical Information of China (English)

    图尔逊艾力·尼亚孜; 艾合买提·阿不来提

    2012-01-01

    In this paper, we mainly study the M/G/l queuing system with multiple working vacation and vacation interruption. First, we convert the mathematical model corresponding to this system into an abstract Cauchy problem. Second, we prove that the operator corresponding this queuing model generates a positive contraction Co-semigroup T(t). Then we show that T(t) is isometric operator. Last, we conclude that this model has a unique nonnegative time-dependent solution.%主要研究工作休假和休假中止的M/G/1排队系统,首先将对应于此系统的数学模型转化为抽象Cauchy问题,其次证明对应于此排队模型的主算子生成正压缩C0半群T(t),然后证明T(t)是局部等距的,最后证明此模型存在唯一的非负时间依赖解.

  9. Monitoring and queuing for sift

    Science.gov (United States)

    Wilson, L.

    1983-01-01

    The SIFT instrumentation is called the "Window." This window was designed to collect internal data from SIFT while having minimal overhead. Window consists of Sender and Relay components. Sender is to be run on processors 0..5 and Relay will run on processor 6. Sender will gather values (currently 12) during the subframe allocated to a task and broadcast these values at the start of the next subframe. This timing was selected to guarantee Relay 3.2ms to collect and transmit the data.

  10. Precautions queuing theory in Agroecology

    Directory of Open Access Journals (Sweden)

    Ю.В. Шмиголь

    2007-03-01

    Full Text Available  In article features of the theory of mass service application in planning of agricultural machines use are submitted with the purpose of reduction of technical loading by the agricultural grounds.

  11. 基于排队论的大型舰船甲板弹射器数量研究%Investigation into Deck Catapults Quantity of Large Ship by Using Queuing Theory

    Institute of Scientific and Technical Information of China (English)

    周鑫磊; 孟祥印; 解学参; 胡玉龙; 侯远杭

    2011-01-01

    The objective of this article is to establish a theoretical basis for determining the quantity of catapult on the flight deck of large ship. As for investigation, the approach of "dummy queue (virtual queue)" was presented from the view of aircraft handling officer, and the task flow model was set up and analysis was carried out by using the queuing theory. The realistic model of task flow of carrier-based aircraft in standby position for launch was also constructed. A multiple calculations were conducted for the key targets, ignoring all the other factors, with regard to the influence of different quantities of catapults on the virtual length of aircraft's waiting queue and time of the system standby based on the assumption of the queuing theory. The results enable to have a quantifying comparison of sortie generation capacities of carried-based aircraft on the flight deck. The calculations also showed that under a given set of conditions, increasing the quantity of the catapult can obviously minimize the queuing length of the birds waiting in a queue for launch on the flight deck, but, if the number of catapult was greater than four, this would be less effective. Through the calculating results, application of the queuing theory to the demonstration as well as quantity design of catapult on large ship is proved to be practicable.%为明确大型舰船飞行甲板弹射器数量设计的理论依据,从调运指挥官的角度提出了"虚拟队列"概念,分析了其工作特点,对其工作模式进行了排队论建模.同时分析、建立了舰载机在弹射等待过程中的真实排队模型.忽略其它甲板因素的影响,基于排队论假设代入数值计算了不同弹射器数量对虚拟队列中舰载机的等待队长、系统等待耗时等关键指标的影响,使弹射器数量影响下的大型舰船舰载机出动能力得到了量化比较.计算结果表明,在给定条件下,甲板弹射器数量的增加能有效减少大型舰船舰

  12. 具有不确定性路径概率的闭排队网络鲁棒控制策略%Robust Control Policy for Closed Queuing Networks with Uncertain Routing Probabilities

    Institute of Scientific and Technical Information of China (English)

    唐昊; 奚宏生; 韩江洪; 袁继彬

    2005-01-01

    The paper is concerned with the robust control problems for exponential controlled closed queuing networks (CCQNs) under uncertain routing probabilities. As the rows of some parameter matrices such as infinitesimal generators may be dependent, we first transform the objective vector under discounted-cost criteria into a weighed-average cost. Through the solution to Poisson equation,i.e., Markov performance potentials, we then unify both discounted-cost and average-cost problems to study, and derive the gradient formula of the new objective function with respect to the routing probabilities. Some solution techniques are related for searching the optimal robust control policy.Finally, a numerical example is presented and analyzed.

  13. Design and Implementation of Triage and Queuing System Based on Outpatient Service Card%基于门诊一卡通的分诊叫号系统设计与实现

    Institute of Scientific and Technical Information of China (English)

    滕丽; 刘长兴

    2014-01-01

    According to the outpatient service process in the hospital, this paper elaborates the hardware system, software system and the functions of the triage and queuing system. The application of the system has optimized the outpatient service process and improved the work efifciency of medical staff and satisfaction degree of patients.%本文结合我院门诊就医流程,阐述了门诊分诊叫号系统的功能设计以及软硬件组成。分诊叫号系统实施以来,优化了就医流程,提高了工作效率和患者的满意度。

  14. 基于闭排队网络的弹射器数量配置方法%Method of the catapult quantity deployed by using closed queuing network

    Institute of Scientific and Technical Information of China (English)

    陈红召; 杨大鹏

    2016-01-01

    The catapult's quantity deployed is a major influencing factor on carrier aircrafts' sortie genera⁃tion rate. In the incipient designing period, the catapult quantity is also one of the important factors. Consid⁃ering the queuing characteristic of the launch process as well as the closed characteristic of the launch and recovery process, this paper proposes a closed queuing network based model for evaluating the influence of the catapult's quantity on sortie generation rate, which can be applied to the design of catapult's quantity. For validation, an example is designed based on the F/A-18's sortie and the recovery process in the Surge operation, whose calculating results agree well with the Surge operation.%弹射器配置数量对舰载机出动回收能力有很大影响,因此,在航母设计初期多方案论证阶段,弹射器的数量配置是必须考虑的关键问题之一。针对舰载机起飞过程的排队特点以及整个出动回收过程的闭环特点,基于排队理论建立舰载机出动回收过程的闭排队网络模型,分析弹射器数量对出动回收能力的影响,分析结果可用于支撑弹射器的数量配置设计方案。为验证模型的有效性,采用“高强度”演习中F/A-18舰载机的数据作为参数输入,结果显示模型计算分析结果与“高强度”演习结果一致。

  15. 基于排队论的电动汽车充电设施优化配置%Optimal Allocation of Charging Facilities for Electric Vehicles Based on Queuing Theory

    Institute of Scientific and Technical Information of China (English)

    李如琦; 苏浩益

    2011-01-01

    在分析电动汽车充电行为的基础上,基于排队论建立了充电设施服务系统排队模型。在此基础上,研究了充电设施服务系统在排队等候中的概率特征,并定量分析了充电设施的运行效率。以充电设施服务系统总费用最小为目标函数建立了充电设施费用最优模型。结合电动汽车充电功率需求预测结果,研究了电动汽车充电设施不同配置方式对电网负荷率的影响。研究结果表明,通过合理配置充电设施,可以提高充电设备综合利用效率,从而进一步验证了所提模型的实用性和有效性。%By analyzing the characteristics of electric vehicles' charging behavior,a queuing model for charging facilities' service system for electric vehicles based on queuing theory is established.On this basis,the waiting probability characteristics of charging facilities' service system for electric vehicles are studied,and the operation efficiency of charging facilities for electric vehicles is analyzed quantitatively.Furthermore,an optimal cost model for electric vehicle charging facilities is developed with the minimum of the total cost of service system as the objective function.By referring to the forecast results of electric vehicles' power demand,the influence of different charging facilities' allocation schemes on load factors of power grid is analyzed.The analysis results show that the synthetic efficiency for charging facilities utilization can be improved by reasonable allocating charging facilities,and the practicality and effectiveness of the model are further verified.

  16. Queuing Aircraft Deicing-dispatch in Multi-deicing Bays Based on Non-cooperative Game Theory%多除冰坪排队飞机除冰过程调度非合作博弈

    Institute of Scientific and Technical Information of China (English)

    邢志伟; 唐广群; 任准

    2013-01-01

    According to the practical situation of aircraft delays in hub airports on snowy days and the current application of multi-deicing bays (MDB),aircraft queuing model of the MDB is established based on multi-server queuing system theory.Besides,the dispatch model of each corresponding holding deicing queue is also established based on game theory.The dynamic flights data of Beijing Capital Airport are used for simulation.The results show that the classification and fair allocation of the deicing bay can decrease the holding time of all the deicing aircrafts in the deicing system and relieve the deicing jam in peak hours,and the model guarantees the fairness of the deicing resources allocation and presents the relationship between MDB input and aircraft's sojourn time.This research also provides a new way for airports' deicing operation and deicing bay construction.%针对冰雪天气大型枢纽机场的大面积航班延误及多除冰坪的实际情况,利用多服务台排队系统理论,建立多除冰坪飞机排队模型,并结合博弈思想建立对应于各等待除冰队列的调度模型.利用首都机场动态航班数据进行仿真计算.仿真结果表明,对除冰位进行分类和合理分配,可以降低所有除冰飞机在除冰系统中的总逗留时间,从而缓解高峰时段除冰坪拥堵情况,给出了除冰坪投入量与飞机逗留时间的关系,保证了除冰资源分配的公平性,为机场地面除冰运行及除冰坪建设提供了一种新的思路.

  17. 采用排队论优化十堰市某医院门诊采血技师配置对患者满意度的影响%Effect of Patient Satisfaction by Queuing Theory in Outpatient Department of Scheduling Blood Collection Technician of a Hospital in Shiyan

    Institute of Scientific and Technical Information of China (English)

    柴海霞; 刘菊英; 王锋; 罗强; 谢飞; 郑苏; 姚红

    2016-01-01

    Objective:To explore the rational allocation of outpatient department blood collection technician of one hospital in Shiyan based on queuing theory and compare the patient satisfaction of outpatient before and after allocating laboratory services. Methods:Time measuring and queuing theory model were applied to calculate commonly used fit index of queuing theory in the technician configuration. The questionnaires were conducted to evaluate patients' satisfaction. Results:Allocating 6 technicians from Monday to Tuesday morning and 5 technicians from Wednesday to Sunday morning were reasonable. The patient satisfaction was improved after adjusting technicians on the basis of queuing theory analysis ( P<0.05) .Conclusion:Queuing theory method can provide reasonable suggestion for staff scheduling,as well as point the new research direction to improve customer satisfaction.%目的::运用排队论分析十堰市某医院门诊采血技师配置的合理性,比较门诊采血技师配置前后患者满意度的变化。方法:运用工时测量法和排队论模型,计算门诊采血排队系统中的各项运行指标,得出合理的技师配置;运用调查问卷评估患者满意度。结果:每周一至周二上午配置6名技师较为合理;周三至周日上午配置5名技师较为合理。根据排队论分析并调整技师排班后,门诊采血窗口患者满意度得到明显提高( P<0.05)。结论:排队论方法可以合理配置采血室的工作人员,同时为研究患者满意度提供新的方向。

  18. Simulation optimization based on production of queuing theory of logistics system%基于排队论的生产物流系统的仿真优化

    Institute of Scientific and Technical Information of China (English)

    马旭耀; 秦现生; 成程

    2012-01-01

    This paper studies configuration problem of logistics and transportation resources in the production process. For improving logistics efficiency in production process and controlling the cost of investment, based on queuing theory, it establishes a comparison model to calculate the waiting cost and the cost of the resources allocation and can select a best plan of resources allocation. In this paper, detailed research and data collection of one enterprise's storage and logistics systems are conducted. It makes a logistics model of production system, simulates with the Arena 7.0 software, so finally a better strategy can be designed and selected.%研究生产过程中物流运输资源配置的问题.为了有效提高企业生产过程中物流效率并控制投资,依据排队理论,建立等待费用和配置资源费用的综合比较模型,从而选择最佳资源配置方案.通过对仓储物流系统的详细调研和数据采集,建立生产系统物流模型,运用Arena 7.0仿真软件进行仿真,从而设计和选择一个较好的策略.

  19. The Method to Determine the Quantity of Integrated Support Equipment Based on Queuing Theory%基于排队论的一体化装备保障设备数量确定方法

    Institute of Scientific and Technical Information of China (English)

    钱潜; 单志伟; 刘福胜; 张波; 李锴

    2015-01-01

    Aiming at solving the unreasonable configuration problem of support equipment in the integra-tive equipment support construction,this thesis is trying to build a support equipment quantity determi-ning model based on queuing theory and solved it using MATLAB software.The reliability of the model is testified with living example,and the change rule of the support equipment quantity is analyzed.Finally, combined with the characteristics of integrative equipment support,new counter measures are put forward for integrative construction,which provides a theoretical basis for the development of integrative equip-ment support.%针对一体化装备保障建设过程中保障设备数量配置不合理的问题,建立了基于排队论的装备保障设备数量确定模型,并运用 MATLAB 软件进行求解。最后,通过实例验证了模型的可靠,,分析了装备保障设备数量的变化规律,并结合一体化装备保障的特点,提出了装备保障设备一体化建设的对策建议,为一体化装备保障的发展奠定了理论基础。

  20. Simulation of queuing model with preemption and impatience customers%带优先权与不耐烦顾客排队模型的模拟仿真

    Institute of Scientific and Technical Information of China (English)

    秦海林; 刘建民

    2012-01-01

    考虑一个有两类顾客到达的单服务台的排队系统.两类顾客的到达过程均为泊松过程,第一类顾客较第二类顾客具有强占优先权,且第二类顾客由于第一类顾客的到达而变得不耐烦,其“耐性时间”服从负指数分布.两类顾客的服务时间服从相同参数的负指数分布,服务规则是强占优先服务,在高负荷条件下用Matlab编程对此排队系统进行模拟仿真,为处理此类排队问题提供了一个新方法.%A single-server queue system with two-class customers is considered. The arrival process of the both two-class customers is Poisson process. The first class customers have the preemptive priority and the second class customers become impatient because of the first class customers' arrival. Their tolerance time is subordinated to the negative exponential distribution. The service discipline is preemptive priority service. Under the condition of high load, the queue system is simulated with Matlab programming. It provided a new method to deal with such a queuing problem.

  1. Two-phases-service queuing system with server breakdown and vacations%带有服务台故障和两阶段服务的休假排队系统

    Institute of Scientific and Technical Information of China (English)

    曾慧; 岳德权

    2011-01-01

    为了解决现实生产生活中的具有两阶段服务性质的休假排队问题,利用马尔可夫过程理论建立系统稳态概率方程组,并利用分块矩阵解法,得到了稳态概率的矩阵解.由此得出系统的平均队长、平均等待队长等性能指标.该成果对解决两阶段服务排队模型具有重要的理论意义和应用价值.%In order to solve the vacation queue problems with a two-phase of service in real-life production, the equations of steady-state probability were derived by applying the Markov process theory in this study. Subsequently, the matrix form solution of steady-state probability was found by using block matrix method. Furthermore, some performance measures of the system, such as the expected number of customers in the system and the expected number of customers in the queue, were also obtained. The study on the queuing systems with two-phase of service is of theoretical significance and application value.

  2. 应急救援物流中物资分发点多目标排队选址优化%Multi-objective queuing location optimization for item distribution spots in emergency relief logistics

    Institute of Scientific and Technical Information of China (English)

    彭翀; 汪传旭; 郭胜童

    2011-01-01

    基于模糊数学、排队理论与选址理论,建立了应急救援物流中物资分发点的多目标模糊排队选址优化模型,其中:受灾点的需求率和物资分发点的服务率为模糊数,物资分发点建立成本最小和救援反应时间最短为目标函数.设计了模型的求解算法,确定了物资分发点的选址以及各个分发点所覆盖的受灾点区域范围.结合具体算例,验证了模型的实用性,并分析了物资分发点应急服务能力对救援效果的影响.%Based on fuzzy mathematics, queuing theory and location theory, a model is introduced into solving the problems about item distribution spots location optimization in emergency relief logistics where the demand rates of disaster spots and service rates of item distribution spots are fuzzy numbers. The proposed model aims at jointly minimi zing the setup costs for item distribution spots and relief response time. The algorithms are presented to set the proposed model to determine the location and covering scope of item distribution spots. A numerical example is given to demonstrate the effectiveness of the proposed model and the impact of service capacity of item distribution spots on re lief performance is analyzed.

  3. 具有不耐烦顾客的M/M/1单重工作休假排队系统%The M/M/1 Queuing System with the Impatient Customers and Single Working Vacation

    Institute of Scientific and Technical Information of China (English)

    徐刚; 于泳波

    2013-01-01

    An M/M/1 queuing system with impatient customers and single working vacation was considered. When a customer arrived in the system and realized that the server was on vacation, he activated an independent ' impatient timer'. If the custmer' s service had not been completed before the customer' s timer expired, the customer abandoned the queue, without returning. Some performance measures of the system were derived such as the mean queue sizes in the busy period and in the working vacation period by balance equations and generating functions. The effects of the two service rates on the system performance measures were investigated by numerical experiment.%讨论了一个具有不耐烦顾客的M/M/1单重工作休假排队系统.工作休假期到达的顾客变得不耐烦并激活一个服从负指数分布的计时器,如果在计时器到期之前顾客没能完成服务,则该顾客离开系统,永不返回.通过平衡方程和母函数推导出正规忙期和工作休假期的平均队长等性能指标的解析表达式.通过数值算例考察了两个服务率对系统性能指标的影响.

  4. Modelo hipercubo integrado a um algoritmo genético para análise de sistemas médicos emergenciais em rodovias The hypercube queuing model integrated to a genetic algorithm to analyze emergency medical systems on highways

    Directory of Open Access Journals (Sweden)

    Ana Paula Iannoni

    2006-04-01

    Full Text Available O modelo hipercubo, conhecido na literatura de problemas de localização de sistemas servidor para cliente, é um modelo baseado em teoria de filas espacialmente distribuídas e aproximações Markovianas. O modelo pode ser modificado para analisar os sistemas de atendimentos emergenciais (SAEs em rodovias, considerando as particularidades da política de despacho destes sistemas. Neste estudo, combinou-se o modelo hipercubo com um algoritmo genético para otimizar a configuração e operação de SAEs em rodovias. A abordagem é efetiva para apoiar decisões relacionadas ao planejamento e operação destes sistemas, por exemplo, em determinar o tamanho ideal para as áreas de cobertura de cada ambulância, de forma a minimizar o tempo médio de resposta aos usuários e o desbalanceamento das cargas de trabalho das ambulâncias. Os resultados computacionais desta abordagem foram analisados utilizando dados reais do sistema Anjos do Asfalto (rodovia Presidente Dutra.The hypercube model, well-known in the literature on problems of server-to-customer localization systems, is based on the spatially distributed queuing theory and Markovian analysis approximations. The model can be modified to analyze Emergency Medical Systems (EMSs on highways, considering the particularities of these systems' dispatching policies. In this study, we combine the hypercube model with a genetic algorithm to optimize the configuration and operation of EMSs on highways. This approach is effective to support planning and operation decisions, such as determining the ideal size of the area each ambulance should cover to minimize not only the average time of response to the user but also ambulance workload imbalances, as well as generating a Pareto efficient boundary between these measures. The computational results of this approach were analyzed using real data Anjos do Asfalto EMS (which covers the Presidente Dutra highway.

  5. Sp ectrum handoff mo del based on preemptive queuing theory in cognitive radio networks%认知无线电网络中基于抢占式排队论的频谱切换模型∗

    Institute of Scientific and Technical Information of China (English)

    杨小龙; 谭学治; 关凯

    2015-01-01

    Cognitive radio can significantly improve spectrum efficiency by temporarily sharing under-utilized licensed fre-quency with primary users. Its spectrum management framework consists of four parts: spectrum sensing, spectrum decision, spectrum sharing and spectrum handoff. The last part is what we focus on in this paper. Spectrum handoff, which aims at guaranteeing requirement for service of secondary users and shortening time delay produced by interrup-tion from primary users, is an important functionality of cognitive radio networks. For solving the problem of optimizing the extended data delivery time, a spectrum handoff model is proposed based on the preemptive resume priority M/G/m queuing theory. In order to minimize the extended data delivery time, the queuing method with mixed queuing and parallel service is adopted. In this model, each channel has its own high-priority queue and there is only one low-priority queue for all secondary users. The primary and secondary users respectively enter into the high-priority and low-priority queue to establish corresponding primary connections and secondary connections and execute corresponding data trans-mission. On the above basis, secondary users’ channel usage behaviors are thoroughly analyzed in the cases of multiple secondary users, multiple licensed channels and multiple spectrum handoffs. In this process, when multiple interruptions occur, the secondary user will stay on the current channel and suspend data transmission until primary users finish their data transmission, otherwise the secondary user will switch from the current channel to the predetermined target channel to resume his unfinished data transmission. The target channel is sequentially obtained from the target channel sequence, which is determined by channel parameter estimation algorithm. Based on the analysis of channel usage behaviors for secondary users, the total time delay caused by spectrum handoffs within the whole data transmission

  6. Coordinating Strategy for Service Supply Chain:Based on Customer Queuing%基于顾客排队的服务供应链协调策略研究

    Institute of Scientific and Technical Information of China (English)

    王文隆; 刘新梅; 王韬

    2014-01-01

    The current research on the service supply chain is still limited by the traditional product supply chainresearch framework.Research on the characteristics of service is the key topic of service supply chain manage -ment.Based on the unique characteristics that service supply chain is customer -oriented, the relationships amonga service provider, an integrator and customers are analyzed firstly.A customer queuing service supply chainmodel is established secondly.Decision problems under centralized and decentralized service supply chain areexplored thirdly.Results indicate that through choosing reasonable cost sharing coefficient and formulating costsharing contract a service provider and a service integrator are able to achieve the Pareto optimal under decentral -ized service supply chain.The results of this study have certain significance for developing and deepening theservice supply chain research.%现阶段对于服务供应链的研究仍受限于传统产品供应链的研究框架,专门针对服务特性的供应链研究是该领域的核心议题。基于服务供应链面向顾客的独有特性,首先分析了服务供应链中服务提供商、集成商与顾客之间的服务关系,然后构建了基于顾客排队的服务供应链模型,其次探讨了集中式和分散式服务供应链下双方的决策问题。研究结果表明,服务提供商、服务集成商通过选择合理的成本共担系数,制定相应的成本共担契约,是协调分散式服务供应链、实现帕累托最优的最佳策略。研究结论对于开拓和深化服务供应链研究具有一定的启示意义。

  7. Bi-level Programming Model for VMS Layout Considering Local Queuing Delay%考虑局部排队延误的VMS选址双层规划模型

    Institute of Scientific and Technical Information of China (English)

    戢晓峰; 覃文文

    2014-01-01

    Using Monte Carlo methodology to characterize randomness of the road network state, a number of candidate variable message signs (VMS) locations are deployed in bottleneck links, and then a bi-objective bi-level programming model is established for optimization of VMS location. The upper level model is a dual-objective programming model considering the minimum of uncertain risk decision-making and the maximum of guidance benefits. The lower level model is stochastic user equilibrium with local network considering queuing delay. The augmented Lagrange dual algorithm combined with method successive average algorithm is adopted to solve the lower model, and the non-dominated sorting genetic algorithm-II (NSGA-II) is adopted to solve the whole bi-level programming. Analysis result indicates that NSGA-II can effectively solve the bi-level programming model of VMS location under the restriction of capital budget, and get 6 Pareto solutions. Outcomes of this research can provide decision support for optimization and construction of VMS layout in uncertain road network.%用Monte Carlo模拟技术刻画路网状态的随机性,优先考虑在交通网络瓶颈路段设置可变信息板待选点,建立多目标优化可变信息板选址双层规划模型。上层模型为基于不确定风险决策最小和诱导效益最大的双目标规划模型,下层模型为考虑局部网络有排队延迟现象的随机用户平衡模型。采用增广Lagrange对偶算法与相继平均算法组合求解下层模型,采用非劣排序遗传算法-II求解整个双层规划模型。算例结果表明,在可变信息板资金预算约束下,非劣排序遗传算法-II能够有效求解可变信息板选址的多目标优化问题,得到6组Pareto解。研究结果可为城市道路网可变信息板诱导配置的优化和建设提供决策支持。

  8. Delay Model of Signalized Intersection Based on Theory of Queuing Systems with Sever Vacations%基于休假随机服务理论的信号交叉口延误模型

    Institute of Scientific and Technical Information of China (English)

    王龙; 陈京荣

    2012-01-01

    Supposing that both arrival rata and saturation flow rata of vehicles at signalized intersection are random variables and they are suitable to Poisson distribution, the queue status at the initial time of red light is studied as the object. Theory of queuing systems with sever vacations is applied to establishing delay model for signalized intersection under non-saturated. According to the process of queue formation and dissipation at entrance lane, the formulation is analyzed and divided into addition delay and random delay, then the formulation of intersection delay is obtained. In the end, based on the analysis and comparison of surveyed data and the result of this paper and the result of literature, the conclusion shows that the model result in this paper is closer to the measured data when saturation is between 0. 4 and 0. 6.%假设信号控制交叉口上车辆的到达率和饱和流率均为服从泊松分布的随机变量,以某一相位红灯初始时刻的排队状态为研究对象,运用休假随机服务系统理论,建立了非饱和状态下的信号交叉口延误模型.根据排队形成和消散的过程,把交叉口进口道上的延误分解成附加延误和随机延误两部分,基于延误三角形和生灭过程的思想,得到了附加延误和随机延误的计算公式,并在此基础上给出了信号交叉口进口道上车辆到达率和饱和流率均服从泊松分布时的车辆平均延误计算公式.将计算结果与交通调查数据和已有文献计算结果进行对比,结果表明当饱和度介于0.4与0.6之间时,模型的计算结果更贴近实测数据.

  9. Queuing delays in randomized load balanced networks

    NARCIS (Netherlands)

    Borst, S.C.; et al, not CWI

    2007-01-01

    Valiant’s concept of Randomized Load Balancing (RLB), also promoted under the name ‘two-phase routing’, has previously been shown to provide a cost-effective way of implementing overlay networks that are robust to dynamically changing demand patterns. RLB is accomplished in two steps; in the first s

  10. Atomic routing in a deterministic queuing model

    Directory of Open Access Journals (Sweden)

    T.L. Werth

    2014-03-01

    We also consider the makespan objective (arrival time of the last user and show that optimal solutions and Nash equilibria in these games, where every user selfishly tries to minimize her travel time, can be found efficiently.

  11. Step tolling with bottleneck queuing congestion

    NARCIS (Netherlands)

    Berg, van den V.A.C.; Verhoef, E.T.; Lindsey, C.R.

    2012-01-01

    . It also proposes a third scheme in which late in the rush hour drivers slow down or stop just before reaching a tolling point, and wait until the toll is lowered from one step to the next step. Such ‘braking’ behaviour has been observed in practice. Analytical derivations and numerical modelling s

  12. Queuing model with variable input rates, mistake service and impatient customers%输入率可变且有差错服务及不耐烦顾客的排队模型分析

    Institute of Scientific and Technical Information of China (English)

    潘全如

    2012-01-01

    在系统顾客容量不变的情况下,顾客到达系统后是否进入系统接受服务对销售行业影响是巨大的.从排队长度对顾客输入率的影响着手,研究了输入率、服务正确率及不耐烦顾客强度均与队长有关的排队模型,得出了进入系统的顾客流是泊松过程.系统中的顾客数是生灭过程,同时求得了系统的队长平稳分布,因没有进入系统而导致系统损失的概率、因不耐烦而离去的顾客的均值、单位时间内系统服务错误率、因系统容量有限而无法加入队列的损失概率等多项指标,得出了并非输入率越高系统就盈利越多、并非系统服务正确率越低系统就赚得越少等结论.还得到了能使企业利润最大化的系统容量及服务速度,为销售行业提高自己的销售业绩提供了很有价值的参考.%The customers do not necessarily get into the system though arriving at it in the case of a fixed customer number, which influences sales industry enormously. Focusing on the influence of queue length on input rate, we build up a queuing model with variable input rates,mistake service and impatient customers, and draw the following conclusions; the customers get into the system in Poissonian flow; the number of customers in the system is a birth-death process. We obtained the stationary queue length distribution of the model, the loss probability for the customers not entering the system while arriving at the system, the mean of the customers who leaves the system due to impatience, the service error rate per unit time and the loss probability for the customers not joining the queue due to the limited capacity of the system and so on. This paper also justifies the falsehood of the following assumptions: the bigger the input rate is, the more profit business will get; the bigger the number of impatient customers is, the less profit business will make. We also obtaind the appropriate service speed and capacity a

  13. The Location-sizing Problem of Electric Vehicle Charging Station Deployment on the Metropolis Based on Queuing Theory%基于排队论的城区内电动汽车充电站选址定容问题研究

    Institute of Scientific and Technical Information of China (English)

    陈文锋

    2016-01-01

    Combined with electric vehicles queuing theory model,study demand mode charging stations,locating and sizing issues in the city.With the expected model,with the greatest tolerance system service charge demand response time expectations based on response time maximum as the objective function to create a long electric vehicle charging station when locating and sizing models.Sensitivity analysis and numerical simulation and analysis of influence of various factors on the results.%结合电动汽车排队论模型,研究点需求模式下城区内充电站选址定容问题。借助期望模型,以最大容忍响应时间内系统所服务充电需求的期望值最大为目标函数,建立一个基于响应时间时长的电动汽车充电站选址定容模型。并且利用数值仿真实验进行灵敏度分析,分析各个影响因素对实验结果的影响。

  14. 具有两阶段服务和服务台故障M/M/1/N多重休假排队系统%The two-Phases-Service M/M/1/N Queuing System with the Server Breakdown and Multiple Vacations

    Institute of Scientific and Technical Information of China (English)

    曾慧; 岳德权

    2011-01-01

    An two-phases-service M/M/l/N queuing system with the server breakdown and multiple vacations was considered. Firstly, equations of steady-state probability were derived by applying the Markov process theory. Then, we obtained matrix form solution of steady-state probability by using blocked matrix method. Finally, some performance measures of the system such as the expected number of customers in the system and the expected number of customers in the queue were also presented.%研究了具有两阶段服务和服务台故障的M/M/1/N多重休假排队系统.利用马尔可夫过程理论建立了系统稳态概率方程组,并利用分块矩阵解法,得到了稳态概率的矩阵解.然后由此得出了系统的平均队长、平均等待队长等性能指标.

  15. 具有负顾客到达和RCH移除策略的GI/D-MSP/1/N离散时间排队系统%Discrete-time GI/D-MSP/1/N queuing system with negative customer arrival and RCH killing policy

    Institute of Scientific and Technical Information of China (English)

    余玅妙; 唐应辉; 付永红; 刘强国

    2011-01-01

    Applying the supplementary variable technique and embedded Markov chain method based on the iteration of conditional probability matrix, we studied a discrete-time GI/D-MSP/1 /N queuing system with negative customer arrival and RCH killing policy. Three kinds of queue length distributions, namely the queue length distribution at positive customer pre-arrival, arbitrary and outside observer's observation epochs, are obtained. Furthermore, we also considered the waiting time distribution of the accessible positive customer. Finally, we presented several numerical examples under some special cases to demonstrate the correctness of the theoretical analysis of this algorithm.%综合运用补充变量方法和基于条件概率矩阵迭代的嵌入Markov链方法研究了具有负顾客到达和RCH移除策略的离散时间GI/D-MSP/1/N排队系统.获得了稳态情形下正顾客到达前夕,任意时隙分点以及外部观测时刻的三种队长分布.并进一步讨论了可入系统正顾客的等待时间分布.最后通过几个特殊情形下的数值算例验证了计算方法理论分析的正确性.

  16. 离散时间 SM[K]/PH[K]/1/FCFS 排队系统的年龄过程改进分析%Analysis and Improvement of the Age Process in a Queuing System of Discrete Time SM[K]/PH[K]/1/FCFS

    Institute of Scientific and Technical Information of China (English)

    高卓; 徐德举

    2015-01-01

    We studied a discrete time queuing system with multiple types of customers and a first-come-first-served (FCFS) service discipline. Customers arrive according to a semi-Markov arrival process and the service times of individual customers have PH-distributions. We studied SM[K]/PH[K]/1/FCFS queue and analyzed its generalized age process particularly. We introduced some auxiliary variables to construct a Markov chain associated with ag(t) and obtained the transition probability matrix of this Markov chain.%基于一个离散时间的排队系统:顾客有着多种类型,成批到达,到达过程是一个半马尔可夫过程,按照先来先服务的准则,并且每一个顾客的服务时间服从各自的 PH 分布。对这个离散时间 SM[K]/PH[K]/1/FCFS 排队系统年龄过程进行了详细分析,引进一些附加变量构造一个关于年龄过程的马尔可夫链,从而计算出年龄过程的转移矩阵。

  17. Einstein Critical-Slowing-Down is Siegel CyberWar Denial-of-Access Queuing/Pinning/ Jamming/Aikido Via Siegel DIGIT-Physics BEC ``Intersection''-BECOME-UNION Barabasi Network/GRAPH-Physics BEC: Strutt/Rayleigh-Siegel Percolation GLOBALITY-to-LOCALITY Phase-Transition Critical-Phenomenon

    Science.gov (United States)

    Buick, Otto; Falcon, Pat; Alexander, G.; Siegel, Edward Carl-Ludwig

    2013-03-01

    Einstein[Dover(03)] critical-slowing-down(CSD)[Pais, Subtle in The Lord; Life & Sci. of Albert Einstein(81)] is Siegel CyberWar denial-of-access(DOA) operations-research queuing theory/pinning/jamming/.../Read [Aikido, Aikibojitsu & Natural-Law(90)]/Aikido(!!!) phase-transition critical-phenomenon via Siegel DIGIT-Physics (Newcomb[Am.J.Math. 4,39(1881)]-{Planck[(1901)]-Einstein[(1905)])-Poincare[Calcul Probabilités(12)-p.313]-Weyl [Goett.Nachr.(14); Math.Ann.77,313 (16)]-{Bose[(24)-Einstein[(25)]-Fermi[(27)]-Dirac[(1927)]}-``Benford''[Proc.Am.Phil.Soc. 78,4,551 (38)]-Kac[Maths.Stat.-Reasoning(55)]-Raimi[Sci.Am. 221,109 (69)...]-Jech[preprint, PSU(95)]-Hill[Proc.AMS 123,3,887(95)]-Browne[NYT(8/98)]-Antonoff-Smith-Siegel[AMS Joint-Mtg.,S.-D.(02)] algebraic-inversion to yield ONLY BOSE-EINSTEIN QUANTUM-statistics (BEQS) with ZERO-digit Bose-Einstein CONDENSATION(BEC) ``INTERSECTION''-BECOME-UNION to Barabasi[PRL 876,5632(01); Rev.Mod.Phys.74,47(02)...] Network /Net/GRAPH(!!!)-physics BEC: Strutt/Rayleigh(1881)-Polya(21)-``Anderson''(58)-Siegel[J.Non-crystalline-Sol.40,453(80)

  18. Autocorrelation in queuing network type production systems - revisited

    DEFF Research Database (Denmark)

    Nielsen, Erland Hejn

    -production systems (Takahashi and Nakamura, 1998) establishes that autocorrelation plays definitely a non-negligible role in relation to the dimensioning as well as functioning of Kanban-controlled production flow lines . This must logically either imply that production managers are missing an important aspect...

  19. Queuing Network Modeling of the Psychological Refractory Period (PRP)

    Science.gov (United States)

    Wu, Changxu; Liu, Yili

    2008-01-01

    The psychological refractory period (PRP) is a basic but important form of dual-task information processing. Existing serial or parallel processing models of PRP have successfully accounted for a variety of PRP phenomena; however, each also encounters at least 1 experimental counterexample to its predictions or modeling mechanisms. This article…

  20. Autocorrelation in queuing network-type production systems - revisited

    DEFF Research Database (Denmark)

    Nielsen, Erland Hejn

    2007-01-01

    In managing production systems, a strong emphasis is placed on the reduction of variance in specific transformation processes (e.g. for quality control purposes) and on controlling the level of variability in general, as for instance with the Bullwhip effect. However, the possible disturbing...

  1. Optimal floating and queuing strategies : The logic of territory choice

    NARCIS (Netherlands)

    Pen, Ido; Weissing, Franz J.

    2000-01-01

    This is a response to a recent article by Hanna Kokko and William J. Sutherland (American Naturalist 152:354-366), who consider evolutionarily stable territory acceptance rules for animals that face the decision between settling on a poor territory now (which is then retained for life) or waiting fo

  2. Understanding human queuing behaviour at exits: an empirical study

    Science.gov (United States)

    Wagoum, A. U. Kemloh; Liao, W.

    2017-01-01

    The choice of the exit to egress from a facility plays a fundamental role in pedestrian modelling and simulation. Yet, empirical evidence for backing up simulation is scarce. In this contribution, we present three new groups of experiments that we conducted in different geometries. We varied parameters such as the width of the doors, the initial location and number of pedestrians which in turn affected their perception of the environment. We extracted and analysed relevant indicators such as distance to the exits and density levels. The results put in evidence the fact that pedestrians use time-dependent information to optimize their exit choice, and that, in congested states, a load balancing over the exits occurs. We propose a minimal modelling approach that covers those situations, especially the cases where the geometry does not show a symmetrical configuration. Most of the models try to achieve the load balancing by simulating the system and solving optimization problems. We show statistically and by simulation that a linear model based on the distance to the exits and the density levels around the exit can be an efficient dynamical alternative. PMID:28280588

  3. Queuing theory models used for port equipment sizing

    Science.gov (United States)

    Dragu, V.; Dinu, O.; Ruscă, A.; Burciu, Ş.; Roman, E. A.

    2017-08-01

    The significant growth of volumes and distances on road transportation led to the necessity of finding solutions to increase water transportation market share together with the handling and transfer technologies within its terminals. It is widely known that the biggest times are consumed within the transport terminals (loading/unloading/transfer) and so the necessity of constantly developing handling techniques and technologies in concordance with the goods flows size so that the total waiting time of ships within ports is reduced. Port development should be achieved by harmonizing the contradictory interests of port administration and users. Port administrators aim profit increase opposite to users that want savings by increasing consumers’ surplus. The difficulty consists in the fact that the transport demand - supply equilibrium must be realised at costs and goods quantities transiting the port in order to satisfy the interests of both parties involved. This paper presents a port equipment sizing model by using queueing theory so that the sum of costs for ships waiting operations and equipment usage would be minimum. Ship operation within the port is assimilated to a mass service waiting system in which parameters are later used to determine the main costs for ships and port equipment.

  4. Affirmative Action Case Queued Up for Airing at High Court

    Science.gov (United States)

    Walsh, Mark

    2012-01-01

    The future of affirmative action in education--not just for colleges but potentially for K-12 schools as well--may be on the line when the U.S. Supreme Court takes up a race-conscious admissions plan from the University of Texas next month. That seems apparent to the scores of education groups that have lined up behind the university with…

  5. Solving Enterprise Applications Performance Puzzles Queuing Models to the Rescue

    CERN Document Server

    Grinshpan, Leonid

    2012-01-01

    A groundbreaking scientific approach to solving enterprise applications performance problems Enterprise applications are the information backbone of today's corporations, supporting vital business functions such as operational management, supply chain maintenance, customer relationship administration, business intelligence, accounting, procurement logistics, and more. Acceptable performance of enterprise applications is critical for a company's day-to-day operations as well as for its profitability. Unfortunately, troubleshooting poorly performing enterprise applications has traditionally

  6. Autocorrelation in queuing network type production systems - revisited

    DEFF Research Database (Denmark)

    Nielsen, Erland Hejn

    -production systems (Takahashi and Nakamura, 1998) establishes that autocorrelation plays definitely a non-negligible role in relation to the dimensioning as well as functioning of Kanban-controlled production flow lines . This must logically either imply that production managers are missing an important aspect...

  7. A Queuing Model-Based System for Triggering Traffic Flow Management Algorithms Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Next generation air traffic management systems are expected use multiple software tools and quantitative methods for managing traffic flow in the National Airspace....

  8. A Serial Queuing Model of the Navy Advanced Traceability and Control (ATAC) System

    Science.gov (United States)

    1991-12-01

    only one supply analyst at NAVMTO is assigned to maintain this very large and complex data system. He is Paul Barraco , Code 033B. Paul is the person... Barraco , Code 033B, NAVMTO via Mike Beliveau, Code 0351, SPCC. We asked Mr. Barraco to provide us with a computer tape of the ATAC data base for the years...1991. If the data is found to b e sufficient, development of an extensive model could begin. Mr. Barraco , NAVMTO should be contacted if me current tapes

  9. Throughput Improvement and Its Tradeoff with The Queuing Delay in the Diamond Relay Networks

    CERN Document Server

    Wang, Qing; Letaief, Khaled Ben

    2009-01-01

    Diamond relay channel model, as a basic transmission model, has recently been attracting considerable attention in wireless Ad Hoc networks. Node cooperation and opportunistic scheduling scheme are two important techniques to improve the performance in wireless scenarios. In the paper we consider such a problem how to efficiently combine opportunistic scheduling and cooperative modes in the Rayleigh fading scenarios. To do so, we first compare the throughput of SRP (Spatial Reused Pattern) and AFP (Amplify Forwarding Pattern) in the half-duplex case with the assumption that channel side information is known to all and then come up with a new scheduling scheme. It will that that only switching between SRP and AFP simply does little help to obtain an expected improvement because SRP is always superior to AFP on average due to its efficient spatial reuse. To improve the throughput further, we put forward a new processing strategy in which buffers are employed at both relays in SRP mode. By efficiently utilizing ...

  10. Designing the optimal robotic milking barn by applying a queuing network approach

    NARCIS (Netherlands)

    Halachmi, I.; Adan, I.J.B.F.; Wald, van der J.; Beek, van P.; Heesterbeek, J.A.P.

    2003-01-01

    The design of various conventional dairy barns is based on centuries of experience, but there is hardly any experience with robotic milking barns (RMB). Furthermore, as each farmer has his own management practices, the optimal layout is `site dependent¿. A new universally applicable design methodolo

  11. Quasi-dynamic network loading: adding queuing and spillback to static traffic assignment

    NARCIS (Netherlands)

    Bliemer, M.C.J.; Brederode, L.J.N.; Wismans, L.J.J.; Smits, E.S.

    2012-01-01

    For many years, static traffic assignment models have been widely applied in transport planning studies and will continue to be an important tool for strategic policy decisions. As is well known, in the traditional approach, the location of the delays and queues are not predicted correctly, and the

  12. A Spatial Queuing-Based Algorithm for Multi-Robot Task Allocation

    Directory of Open Access Journals (Sweden)

    William Lenagh

    2015-08-01

    Full Text Available Multi-robot task allocation (MRTA is an important area of research in autonomous multi-robot systems. The main problem in MRTA is to allocate a set of tasks to a set of robots so that the tasks can be completed by the robots while ensuring that a certain metric, such as the time required to complete all tasks, or the distance traveled, or the energy expended by the robots is reduced. We consider a scenario where tasks can appear dynamically and a task needs to be performed by multiple robots to be completed. We propose a new algorithm called SQ-MRTA (Spatial Queueing-MRTA that uses a spatial queue-based model to allocate tasks between robots in a distributed manner. We have implemented the SQ-MRTA algorithm on accurately simulated models of Corobot robots within the Webots simulator for different numbers of robots and tasks and compared its performance with other state-of-the-art MRTA algorithms. Our results show that the SQ-MRTA algorithm is able to scale up with the number of tasks and robots in the environment, and it either outperforms or performs comparably with respect to other distributed MRTA algorithms.

  13. A Case Study of Employing A Single Server Nonpreemptive Priority Queuing Model at ATM Machine

    OpenAIRE

    Abdullah Furquan; Abdullah Imran

    2015-01-01

    This paper discusses a case study of employing a single server nonpreemptivepriorityqueuing model [1]at ATM machine which originally operates on M/M/1 model. In this study we have taken two priority classes of people in following order:- .Priority class 1- woman .Priority class 2- man Sometimea long queue is formed at ATMmachine (single server)but the bank management don’t have enough money to invest on installing new ATM machine.In this situation we want to apply single ser...

  14. Redesign of a university hospital preanesthesia evaluation clinic using a queuing theory approach

    NARCIS (Netherlands)

    Zonderland, M.E.; Boer, F.; Boucherie, R.J.; Roode, de A.; Kleef, van J.W.

    2009-01-01

    Background Changes in patient length of stay (the duration of one visit) as a result of the introduction of an electronic patient file system forced an anesthesia department to change their outpatient clinic organization. The aim of this study is to demonstrate how the involvement of essential emplo

  15. Optimisation of a honeybee-colony's energetics via social learning based on queuing delays

    Science.gov (United States)

    Thenius, Ronald; Schmickl, Thomas; Crailsheim, Karl

    2008-06-01

    Natural selection shaped the foraging-related processes of honeybees in such a way that a colony can react to changing environmental conditions optimally. To investigate this complex dynamic social system, we developed a multi-agent model of the nectar flow inside and outside of a honeybee colony. In a honeybee colony, a temporal caste collects nectar in the environment. These foragers bring their harvest into the colony, where they unload their nectar loads to one or more storer bees. Our model predicts that a cohort of foragers, collecting nectar from a single nectar source, is able to detect changes in quality in other food sources they have never visited, via the nectar processing system of the colony. We identified two novel pathways of forager-to-forager communication. Foragers can gain information about changes in the nectar flow in the environment via changes in their mean waiting time for unloadings and the number of experienced multiple unloadings. This way two distinct groups of foragers that forage on different nectar sources and that never communicate directly can share information via a third cohort of worker bees. We show that this noisy and loosely knotted social network allows a colony to perform collective information processing, so that a single forager has all necessary information available to be able to 'tune' its social behaviour, like dancing or dance-following. This way the net nectar gain of the colony is increased.

  16. Queuing and convergence properties of a dynamic assignment model for congested networks

    NARCIS (Netherlands)

    Troost, J.F.; Botma, H.; Bovy, P.H.L.

    1996-01-01

    The growing congestion problems demand a new generation of traffic models that are applicable in the planning and management of infrastructure. The aim of this thesis is the development of a traffic model able to predict congestions and their influence on traffic operation. This model is meant for

  17. Queued History based Mediator Identification for an Incentive Attached peer to peer Electronic Coupon System

    Science.gov (United States)

    Shojima, Taiki; Ikkai, Yoshitomo; Komoda, Norihisa

    An incentive attached peer to peer (P2P) electronic coupon system is proposed in which users forward e-coupons to potential users by providing incentives to those mediators. A service provider needs to acquire distribution history for incentive payment by recording UserIDs (UIDs) in the e-coupons, since this system is intended for pure P2P environment. This causes problems of dishonestly altering distribution history. In order to solve such problems, distribution history is realized in a couple of queues structure. They are the UID queue, and the public key queue. Each element of the UID queue at the initial state consists of index, a secret key, and a digital signature. In recording one's UID, the encrypted UID is enqueued to the UID queue with a new digital signature created by a secret key of the dequeued element, so that each UID cannot be altered. The public key queue provides the functionality of validating digital signatures on mobile devices. This method makes it possible both each UID and sequence of them to be certificated. The availability of the method is evaluated by quantifying risk reduction using Fault Tree Analysis (FTA). And it's recognized that the method is better than common encryption methods.

  18. Paying for express checkout: competition and price discrimination in multi-server queuing systems.

    Directory of Open Access Journals (Sweden)

    Cary Deck

    Full Text Available We model competition between two firms selling identical goods to customers who arrive in the market stochastically. Shoppers choose where to purchase based upon both price and the time cost associated with waiting for service. One seller provides two separate queues, each with its own server, while the other seller has a single queue and server. We explore the market impact of the multi-server seller engaging in waiting cost-based-price discrimination by charging a premium for express checkout. Specifically, we analyze this situation computationally and through the use of controlled laboratory experiments. We find that this form of price discrimination is harmful to sellers and beneficial to consumers. When the two-queue seller offers express checkout for impatient customers, the single queue seller focuses on the patient shoppers thereby driving down prices and profits while increasing consumer surplus.

  19. Paying for express checkout: competition and price discrimination in multi-server queuing systems.

    Science.gov (United States)

    Deck, Cary; Kimbrough, Erik O; Mongrain, Steeve

    2014-01-01

    We model competition between two firms selling identical goods to customers who arrive in the market stochastically. Shoppers choose where to purchase based upon both price and the time cost associated with waiting for service. One seller provides two separate queues, each with its own server, while the other seller has a single queue and server. We explore the market impact of the multi-server seller engaging in waiting cost-based-price discrimination by charging a premium for express checkout. Specifically, we analyze this situation computationally and through the use of controlled laboratory experiments. We find that this form of price discrimination is harmful to sellers and beneficial to consumers. When the two-queue seller offers express checkout for impatient customers, the single queue seller focuses on the patient shoppers thereby driving down prices and profits while increasing consumer surplus.

  20. Stochastic Queuing Model Analysis to Support Airspace Super Density Operations (ASDO) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has been involved in extensive research efforts to develop advanced concepts and technologies, for the Next Generation Air Transportation System (NextGen) under...

  1. Redesign of a university hospital preanesthesia evaluation clinic using a queuing theory approach

    NARCIS (Netherlands)

    Zonderland, Maartje E.; Boer, Fredrik; Boucherie, Richard J.; Roode, de Annemiek; Kleef, van Jack W.

    2009-01-01

    BACKGROUND: Changes in patient length of stay (the duration of 1 clinic visit) as a result of the introduction of an electronic patient file system forced an anesthesia department to change its outpatient clinic organization. In this study, we sought to demonstrate how the involvement of essential e

  2. Numerical analysis of minimum cost network flow with queuing stations: the M/M/1 case

    Directory of Open Access Journals (Sweden)

    Salvador Hernández-González

    2017-01-01

    Full Text Available En una red los nodos representan estaciones, almacenes, centros de distribución y c lientes y circulan tanto materiales como información, por lo que una herramienta utilizada para apoyar la toma de decisiones es el modelo de flujo a costo mínimo que toma en cuenta únicamente costos de transporte. En la realidad los nodos prestan un servic io el cual requiere un tiempo de servicio, la atención sigue una disciplina y además se forma una fila de espera. En este trabajo se propone una modificación del modelo de flujo a costo mínimo para la optimización en redes de líneas de espera. Se resolvier on varios casos donde se observa un grado de exactitud aceptable en el cálculo del tiempo de ciclo y trabajo en proceso. El trabajo es de interés para los administradores y/o responsables de las cadenas de abasto y útil para la toma de dec i siones a mediano y largo plazo.

  3. Integration of look-ahead multicast and unicast scheduling for input-queued cell switches

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2012-01-01

    -ofline (HOL) blocking problem that the weight-based algorithm (WBA) suffers from. Leveraging the FILter & Merge (FILM) scheme, multicast and unicast traffic are independently scheduled based on their requests. Decisions are integrated following a specific policy. Remainder is looped back to the filtering...... module that filters out the conflicting requests to ensure fairness. Simulation results show that comparing with the scheme using WBA for the multicast scheduling, the scheme proposed in this paper reduces the HOL blocking problem for multicast traffic and provides a significant improvement in terms...

  4. Cosmic queuing: galaxy satellites, building blocks and the hierarchical clustering paradigm

    CERN Document Server

    Lagos, Claudia del P; Cora, Sofia A

    2009-01-01

    We study the properties of building blocks (BBs, i.e. accreted satellites) and surviving satellites of present-day galaxies using the SAG semi-analytic model of galaxy formation in the context of a concordance Lambda Cold Dark Matter (LCDM) cosmology. We find higher metallicities for BBs, an effect produced by the same processes behind the build-up of the mass-metallicity relation, namely, the higher peak height in the density fluctuation field occupied by BBs and central galaxies which have collapsed into a single object earlier than surviving satellites. A detailed analysis shows that BBs start to form stars earlier, and build-up half of their final stellar mass (measured at the moment of disruption) up to four times faster than surviving satellites. We show that this effect is a consequence of the epoch in which this occurs; BBs assemble their stellar mass mostly during the peak of the merger activity in the LCDM cosmology, whereas surviving satellites keep increasing their stellar masses down to z=1. The ...

  5. UPnP QoS and queuing in home networks

    DEFF Research Database (Denmark)

    Brewka, Lukasz Jerzy; Wessing, Henrik; Dittmann, Lars

    2010-01-01

    The QoS provisioning in home networks is being more often considered for future use cases, where mulitple high bandwidth flows are accomodated in the home environment. This paper investigates chosen characteristics of one of the home network control and management protocol suites, namely UPn......P. Using network modeling tools, we evaluate UPnP QoS architecture and its resource management influence on the end-to-end packet delay characteristics for different scheduling approaches....

  6. A queuing model for designing multi-modality buried target detection systems: preliminary results

    Science.gov (United States)

    Malof, Jordan M.; Morton, Kenneth D.; Collins, Leslie M.; Torrione, Peter A.

    2015-05-01

    Many remote sensing modalities have been developed for buried target detection, each one offering its own relative advantages over the others. As a result there has been interest in combining several modalities into a single detection platform that benefits from the advantages of each constituent sensor, without suffering from their weaknesses. Traditionally this involves collecting data continuously on all sensors and then performing data, feature, or decision level fusion. While this is effective for lowering false alarm rates, this strategy neglects the potential benefits of a more general system-level fusion architecture. Such an architecture can involve dynamically changing which modalities are in operation. For example, a large standoff modality such as a forward-looking infrared (FLIR) camera can be employed until an alarm is encountered, at which point a high performance (but short standoff) sensor, such as ground penetrating radar (GPR), is employed. Because the system is dynamically changing its rate of advance and sensors, it becomes difficult to evaluate the expected false alarm rate and advance rate. In this work, a probabilistic model is proposed that can be used to estimate these quantities based on a provided operating policy. In this model the system consists of a set of states (e.g., sensors employed) and conditions encountered (e.g., alarm locations). The predictive accuracy of the model is evaluated using a collection of collocated FLIR and GPR data and the results indicate that the model is effective at predicting the desired system metrics.

  7. Stochastic Queuing Model Analysis to Support Airspace Super Density Operations (ASDO) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has been involved in extensive research efforts to develop advanced concepts, technologies, and procedures for the Next Generation Air Transportation System...

  8. Extended Delivery Time Analysis for Cognitive Packet Transmission With Application to Secondary Queuing Analysis

    KAUST Repository

    Usman, Muneer

    2015-05-21

    Cognitive radio transceiver can opportunistically access the underutilized spectrum resource of primary systems for new wireless services. With interweave implementation, the secondary transmission may be interrupted by the primary user\\'s transmission. To facilitate the delay analysis of such secondary transmission for fixed-size secondary packets, we study the resulting extended delivery time that includes both transmission time and waiting time. In particular, we derive the exact distribution functions of extended delivery time of secondary transmission for both continuous sensing and periodic sensing cases. Selected numerical and simulation results are presented for illustrating the mathematical formulation. Finally, we consider an M/G/1 queueing set-up at the secondary transmitter and formulate the closed-form expressions for the expected delay with Poisson traffic. The analytical results will greatly facilitate the design of the secondary system for particular target application. © 2015 IEEE.

  9. Deciding stability under FIFO in the adversarial queuing model in polynomial time

    OpenAIRE

    Blesa Aguilera, Maria Josep

    2005-01-01

    In spite of the importance of the FIFO protocol and the research efforts invested in obtaining results for it, deciding whether a given network is stable under FIFO was still an open question. In this work, we address the general case of this problem and try to characterize the property of stability under FIFO in terms of network topologies. We show that this property is decidable in polynomial time.

  10. Feature analysis for closed queuing system with non-preemptive priorities

    Directory of Open Access Journals (Sweden)

    Yu. G. Nesterov

    2014-01-01

    Full Text Available The object of research in this article is to obtain the analytical expressions for the probability distribution functions (PDF of states of the closed system of mass service (SMS like "model of the repairman" Mr|GIr|1 || Nr in a stationary mode. The SMS has a source of requests of final capacity with exponentially distributed time of residence of different class requests in the source, one queue with discipline of requests service i.e. the non-preemptive priorities, one serving device (SD and arbitrary PDF of a residence time of each class requests.The method includes the following steps.The first step, while servicing the non-uniform population of requests, distinguishes a sequence of time points, so-called points of regeneration in which a process behaves as Markov's. It is shown that such points are time points to complete a service of requests in SD. Further, for these points an embedded Markov's chain is designed, and the states space of this chain is defined. Analytical expressions to calculate the elements of transition probability matrix in such chain are obtained. These expressions reflect a relationship between these probabilities and the source parameters, the residence time PDF parameters, the number of each class requests, and a discipline of their service. Further, the solution for PDF of this chain states is found.The second step establishes connection between the PDF of SMS states in a stationary mode and the previously received PDF of states of the embedded Markov's chain. Such connection is defined by a system of the equations of global balance for the SMS states in a stationary mode and states of the embedded Markov's chain. The physical sense of such balance is that each of SMS state in a stationary mode is in equilibrium, i.e. the intensities of transitions from the state and in the state are equal. The space of states of initial SMS in a stationary mode is defined. It is shown that in intervals of request service time in SD the process behaves as a process of net reproduction when intensity of death – transition of SMS to "lower" states – is equal to zero. The paper presents the obtained analytical expressions to calculate the stationary PDF of given SMS depending on the PDF of the embedded Markov' chain, the discipline of service, and the PDF of residence times to serve different class requests in SD.The third step provides expressions to calculate the average values of residence and waiting times of each class requests in SMS, as well as expressions to define the SD loading by requests of each class and the general loading of SD. The formulas development is based on conservatism (work preservation, fair for discipline of service with non-preemptive priorities, and also using Little's result and expressions for average number of requests of each class in SMS which, in turn, are defined by the PDF of SMS states in a stationary mode.

  11. Performance evaluation of an optical hybrid switch with circuit queued reservations and circuit priority preemption

    Science.gov (United States)

    Wong, Eric W. M.; Zukerman, Moshe

    2006-11-01

    We provide here a new loss model for an optical hybrid switch that can function as an optical burst switch and/or optical circuit switch. Our model is general as it considers an implementation whereby some of the circuits have preemptive priority over bursts and others are allowed to queue their reservations. We first present an analysis based on a 3-dimension state-space Markov chain that provides exact results for the blocking probabilities of bursts and circuits, the proportion of circuits that are delayed and the mean delay of the circuits that are delayed. Because it is difficult to exactly compute the blocking probability in realistic scenarios with a large number of wavelengths, we derive computationally a scalable and accurate approximations based on reducing the 3-dimension state space into a single dimension. These scalable approximations that can produce performance results in a fraction of a second can readily enable switch dimensioning. Extensive numerical results are presented to demonstrate the accuracy and the use of the new approximations.

  12. First passage processes in Queuing system MX/Gr/1 with service delay discipline

    Directory of Open Access Journals (Sweden)

    Lev Abolnikov

    1994-01-01

    Full Text Available This article deals with a general single-server bulk queueing system with a server waiting until the queue will reach level r before it starts processing customers. If at least r customers are available the server takes a batch of the fixed size r of units for service. The input stream is assumed to be a compound Poisson process modulated by a semi-Markov process and with a multilevel control of service time.

  13. Performance evaluation of railway blocking system based on markov chain and queuing theory

    Science.gov (United States)

    Guo, Jin; Chen, Hongxia; Yang, Yang

    2005-12-01

    Railway blocking system is the system with the high demanding of real-time performance. Firstly, the tasks and the time limits, which had to be handled for the blocking system, were introduced. The FCFS and the Markov chain were used to set the model for it. By analyzing the performance of the system with the FCFS model found out that it was not satisfied to the real-time performance. Secondly, NPPR model to evaluate the software real-time performance of the blocking processor was proposed. By evaluation, analysis and comparison, the results indicate that the NPPR model is prevail over the model of (M/M/1): (N/N/FCFS) in real-time performance. And the priorities of the tasks in the system should be given according to their time limit. With the principle of (M/M/1): (N/N/NPPR), if the priority was given to the tasks properly, the satisfied real-time performance will be gotten. The models were tested in forms software and the satisfied result has been gotten in practice.

  14. Optimal choice of Reed-Solomon codes to protect against queuing losses in wireless networks

    Institute of Scientific and Technical Information of China (English)

    Claus Bauer; JIANG Wen-yu

    2009-01-01

    This article proposes algorithms to determine an optimal choice of the Reed-Solomon forward error correction (FEC) code parameters (n,k) to mitigate the effects of packet loss on multimedia traffic caused by buffer overflow at a wireless base station. A network model is developed that takes into account traffic arrival rates, channel loss characteristics, the capacity of the buffer at the base station, and FEC parameters. For Poisson distributed traffic, the theory of recurrent linear equations is applied to develop a new closed form solution of low complexity of the Markov model for the buffer occupancy. For constant bit rate (CBR) traffic,an iterative procedure is developed to compute the packet loss probabilities after FEC recovery.

  15. Congestion at Card and Book Catalogs--A Queuing Theory Approach.

    Science.gov (United States)

    Bookstein, Abraham

    The question of whether a library's catalog should consist of cards arranged in a single alphabetical order (the "dictionary catalog) or be segregated as a separate file is discussed. Development is extended to encompass related problems involved in the creation of a book catalog. A model to study the effects of congestion at the catalog is…

  16. An application of queuing theory to SIS and SEIS epidemic models.

    Science.gov (United States)

    Hernandez-Suarez, Carlos M; Castillo-Chavez, Carlos; Lopez, Osval Montesinos; Hernandez-Cuevas, Karla

    2010-10-01

    In this work we consider every individual of a population to be a server whose state can be either busy (infected) or idle (susceptible). This server approach allows to consider a general distribution for the duration of the infectious state, instead of being restricted to exponential distributions. In order to achieve this we first derive new approximations to quasistationary distribution (QSD) of SIS (Susceptible- Infected- Susceptible) and SEIS (Susceptible- Latent- Infected- Susceptible) stochastic epidemic models. We give an expression that relates the basic reproductive number, R0 and the server utilization,p.

  17. Congestion at Card and Book Catalogs--A Queuing-Theory Approach

    Science.gov (United States)

    Bookstein, Abraham

    1972-01-01

    This paper attempts to analyze the problem of congestion, using a mathematical model shown to be of value in other similar applications. Three criteria of congestion are considered, and it is found that the conclusion one can draw is sensitive to which of these criteria is paramount. (8 references) (Author/NH)

  18. Using Queuing Theory and Simulation Modelling to Reduce Waiting Times in An Iranian Emergency Department

    Directory of Open Access Journals (Sweden)

    Hourvash Akbari Haghighinejad

    2016-01-01

    Full Text Available Background: Hospital emergencies have an essential role in health care systems. In the last decade, developed countries have paid great attention to overcrowding crisis in emergency departments. Simulation analysis of complex models for which conditions will change over time is much more effective than analytical solutions and emergency department (ED is one of the most complex models for analysis. This study aimed to determine the number of patients who are waiting and waiting time in emergency department services in an Iranian hospital ED and to propose scenarios to reduce its queue and waiting time. Methods: This is a cross-sectional study in which simulation software (Arena, version 14 was used. The input information was extracted from the hospital database as well as through sampling. The objective was to evaluate the response variables of waiting time, number waiting and utilization of each server and test the three scenarios to improve them. Results: Running the models for 30 days revealed that a total of 4088 patients left the ED after being served and 1238 patients waited in the queue for admission in the ED bed area at end of the run (actually these patients received services out of their defined capacity. The first scenario result in the number of beds had to be increased from 81 to179 in order that the number waiting of the “bed area” server become almost zero. The second scenario which attempted to limit hospitalization time in the ED bed area to the third quartile of the serving time distribution could decrease the numberwaiting to 586 patients. Conclusion: Doubling the bed capacity in the emergency department and consequently other resources and capacity appropriately can solve the problem. This includes bed capacity requirement for both critically ill and less critically ill patients. Classification of ED internal sections based on severity of illness instead of medical specialty is another solution.

  19. Modeling the emergency cardiac in-patient flow: an application of queuing theory.

    Science.gov (United States)

    de Bruin, Arnoud M; van Rossum, A C; Visser, M C; Koole, G M

    2007-06-01

    This study investigates the bottlenecks in the emergency care chain of cardiac in-patient flow. The primary goal is to determine the optimal bed allocation over the care chain given a maximum number of refused admissions. Another objective is to provide deeper insight in the relation between natural variation in arrivals and length of stay and occupancy rates. The strong focus on raising occupancy rates of hospital management is unrealistic and counterproductive. Economies of scale cannot be neglected. An important result is that refused admissions at the First Cardiac Aid (FCA) are primarily caused by unavailability of beds downstream the care chain. Both variability in LOS and fluctuations in arrivals result in large workload variations. Techniques from operations research were successfully used to describe the complexity and dynamics of emergency in-patient flow.

  20. Using Queuing Theory and Simulation Modelling to Reduce Waiting Times in An Iranian Emergency Department.

    Science.gov (United States)

    Haghighinejad, Hourvash Akbari; Kharazmi, Erfan; Hatam, Nahid; Yousefi, Sedigheh; Hesami, Seyed Ali; Danaei, Mina; Askarian, Mehrdad

    2016-01-01

    Hospital emergencies have an essential role in health care systems. In the last decade, developed countries have paid great attention to overcrowding crisis in emergency departments. Simulation analysis of complex models for which conditions will change over time is much more effective than analytical solutions and emergency department (ED) is one of the most complex models for analysis. This study aimed to determine the number of patients who are waiting and waiting time in emergency department services in an Iranian hospital ED and to propose scenarios to reduce its queue and waiting time. This is a cross-sectional study in which simulation software (Arena, version 14) was used. The input information was extracted from the hospital database as well as through sampling. The objective was to evaluate the response variables of waiting time, number waiting and utilization of each server and test the three scenarios to improve them. Running the models for 30 days revealed that a total of 4088 patients left the ED after being served and 1238 patients waited in the queue for admission in the ED bed area at end of the run (actually these patients received services out of their defined capacity). The first scenario result in the number of beds had to be increased from 81 to179 in order that the number waiting of the "bed area" server become almost zero. The second scenario which attempted to limit hospitalization time in the ED bed area to the third quartile of the serving time distribution could decrease the number waiting to 586 patients. Doubling the bed capacity in the emergency department and consequently other resources and capacity appropriately can solve the problem. This includes bed capacity requirement for both critically ill and less critically ill patients. Classification of ED internal sections based on severity of illness instead of medical specialty is another solution.

  1. The effect of network structure on phase transitions in queuing networks

    CERN Document Server

    Barankai, Norbert; Vattay, Gábor

    2012-01-01

    Recently, De Martino et al have presented a general framework for the study of transportation phenomena on complex networks. One of their most significant achievements was a deeper understanding of the phase transition from the uncongested to the congested phase at a critical traffic load. In this paper, we also study phase transition in transportation networks using a discrete time random walk model. Our aim is to establish a direct connection between the structure of the graph and the value of the critical traffic load. Applying spectral graph theory, we show that the original results of De Martino et al showing that the critical loading depends only on the degree sequence of the graph -- suggesting that different graphs with the same degree sequence have the same critical loading if all other circumstances are fixed -- is valid only if the graph is dense enough. For sparse graphs, higher order corrections, related to the local structure of the network, appear.

  2. Priority-based queuing and transmission rate management using a fuzzy logic controller in WSNs

    Directory of Open Access Journals (Sweden)

    Imen Bouazzi

    2017-06-01

    Full Text Available Wireless sensor networks (WSNs operate under challenging conditions, such as maintaining message latency and the reliability of data transmission and maximizing the battery life of sensor nodes. The aim of this study is to propose a fuzzy logic algorithm for solving these issues, which are difficult to address with traditional techniques. The idea, in this study, is to employ a fuzzy logic scheme to optimize energy consumption and minimize packet drops. We demonstrated how fuzzy logic can be used to tackle this specific communication problem with minimal computational complexity. In this context, the implementation of a fuzzy logic in the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA mechanism is achieved through filling the queue length and the traffic rate at each node. Through simulations, we show that our proposed technique has a better performance in terms of energy consumption compared to the basic implementation of CSMA/CA.

  3. 虚拟顾客服务系统排队模型%Queuing model in virtual service support system

    Institute of Scientific and Technical Information of China (English)

    宋卫斌; 苏秦

    2001-01-01

    通过对虚拟企业售后服务部门的顾客排队网络的分析,确定了一种顾客具有优先权的多级顾客服务排队模型.以顾客满意度为条件计算出了稳定平衡状态下排队系统的主要指标,并从收益、成本和效率等方面建立了排队系统的优化问题,从而可得到服务部门最优基准服务能力.基准服务能力的确定,对服务能力的有效安排和组织具有重要的指导意义.%By analyzing the queue net of service support system in virtual enterprise, the authors establish a multi-state and priority customer services model. According to the customer satisfaction, the model under the steadily state is calculated. Meanwhile, the result of model are optimized from cost, income and efficiency of the services operation department. The base service capability is got, which give important direction to arrange and organize services ability of virtual enterprises.

  4. How do queuing concepts and tools help to efficiently manage hospitals when the patients are impatient? A demonstration

    Directory of Open Access Journals (Sweden)

    Ramalingam Shanmugam

    2014-06-01

    Results: Using the new ideas and formulas of this article, the data in the emergency wing of a hospital in Malta (a largest island of an archipelago situated in the center of the Mediterranean with a total population of a million are analyzed and interpreted. The results clearly explain why there were a prolonged waiting times at the emergency department creating public dissatisfaction and patients were leaving without waiting to be seen. The total time spent by non-urgent patients with nurse and casualty officer is more in the second shift and lesser and lesser in the third and fourth shifts. The interactive time with a nurse by patient is statistically same in all three types: life-threatening, non-life threatening but urgent, and non-urgent. Very strikingly, the patients in all three groups wait longer to be seen by the nurse in shift three and lesser time in shifts two or four. Conclusion: In 21st century with flourishing globalized medical tourism, a standardized approach to minimize efficiently the waiting time in emergency and other wings of the hospitals in developing as much as in developed nations is a necessity as this auricle has pointed out. The impediments and the remedies for an efficient standardization are overdue. [Int J Res Med Sci 2014; 2(3.000: 1076-1084

  5. Radio Frequency Identification Queuing & Geo-Location (RAQGEO): A spatial solution to inventory management at XYZ Logistics, Inc

    Science.gov (United States)

    Griffiths, Bradley Joseph

    New supply chain management methods using radio frequency identification (RFID) and global positioning system (GPS) technology are quickly being adopted by companies as various inventory management benefits are being realized. For example, companies such as Nippon Yusen Kaisha (NYK) Logistics use the technology coupled with geospatial support systems for distributors to quickly find and manage freight containers. Traditional supply chain management methods require pen-to-paper reporting, searching inventory on foot, and human data entry. Some companies that prioritize supply chain management have not adopted the new technology, because they may feel that their traditional methods save the company expenses. This thesis serves as a pilot study that examines how information technology (IT) utilizing RFID and GPS technology can serve to increase workplace productivity, decrease human labor associated with inventorying, plus be used for spatial analysis by management. This pilot study represents the first attempt to couple RFID technology with Geographic Information Systems (GIS) in supply chain management efforts to analyze and locate mobile assets by exploring costs and benefits of implementation plus how the technology can be employed. This pilot study identified a candidate to implement a new inventory management method as XYZ Logistics, Inc. XYZ Logistics, Inc. is a fictitious company but represents a factual corporation. The name has been changed to provide the company with anonymity and to not disclose confidential business information. XYZ Logistics, Inc., is a nation-wide company that specializes in providing space solutions for customers including portable offices, storage containers, and customizable buildings.

  6. The consequences of heavy-tailed service time distribution on a basic queuing model and its performance indicators

    Directory of Open Access Journals (Sweden)

    Lina M. Rangel Martínez

    2010-06-01

    Full Text Available Recent research showing theoretical generative models for heavy-tailed service time queues and its empirical validation implies the need for a better knowledge of the key performance indicators’ behavior under such assumption. The behavior of the average length of the queue ( and the average waiting-time (Wq were analyzed through simulation, varying system capacity, average service utilization factor ( ρ and the number of servers in the systems as parameters. Comparisons were also made with service times based on Poisson processes. The results showed more sensitive variations of Lq and Wq for heavy-tailed service times than for Poisson-based service times. Systems having a capacity of over 1,000 entities might be considered as being systems having infinity capacity and the number of servers has a greater importance in heavy-tailed ruled processes than in Poisson processes. There was a lack of adequacy of Lq and Wq as key performance indicators for heavy-tailed service times, lea- ding to unexpected and unstable results.

  7. Vested Interests in Queuing and the Loss of the WTO's Club Good: The Long-run Costs of US Bilateralism

    OpenAIRE

    Kerr, William A.

    2005-01-01

    In recent years the United States has actively begun to engage in the negotiation of bilateral and regional trade agreements, a significant change from its long-standing commitment to the exclusive use of multilateral institutions for trade liberalization. While the "unequal economic power" effects of the strategic use of trade policy are well understood, the long-run implications of the creation of a queue for bilateral negotiations have been less fully explored. It is argued here that queui...

  8. Quality and operations of portable X-ray examination procedures in the emergency room: queuing theory at work.

    Science.gov (United States)

    Abujudeh, Hani; Vuong, Bill; Baker, Stephen R

    2005-07-01

    The objective of this study was to evaluate the operation of the portable X-ray machine in relation to examinations ordered by the Emergency Department at the University of Medicine and Dentistry of New Jersey, as well as to identify any bottlenecks hindering the performance of the aforementioned system. To do so, the activity of the portable X-ray was monitored in the period from 8 June 2004 to 24 June 2004, as well as from 6 July 2004 to 12 July 2004, yielding 11 days of data and 116 individual X-ray examinations. During observation times was noted for various checkpoints in the procedure. Using the data gathered, the average input, output, processing times, and variance were calculated. In turn, these values were used to calculate the response times for the Ordering Phase (5.502 min), traveling (2.483 min), Examination Phase (4.453 min), returning (3.855 min), Order Processing Phase (2.962 min), and the Development Phase (3.437 min). These phases were combined for a total of 22.721 min from the time the examination was placed to the time the X-ray films were uploaded to the PACS computer network. Based on these calculations, the Ordering Phase was determined to be the single largest bottleneck in the portable X-ray system. The Examination Phase also represented the second largest bottleneck for a combined total of 44% of the total response time.

  9. An Improved μTESLA Protocol Based on Queuing Theory and Benaloh-Leichter SSS in WSNs

    Directory of Open Access Journals (Sweden)

    Haiping Huang

    2016-01-01

    Full Text Available Broadcast authentication is a fundamental security technology in wireless sensor networks (ab. WSNs. As an authentication protocol, the most widely used in WSN, μTESLA protocol, its publication of key is based on a fixed time interval, which may lead to unsatisfactory performance under the unstable network traffic environment. Furthermore, the frequent network communication will cause the delay authentication for some broadcast packets while the infrequent one will increase the overhead of key computation. To solve these problems, this paper improves the traditional μTESLA by determining the publication of broadcast key based on the network data flow rather than the fixed time interval. Meanwhile, aiming at the finite length of hash chain and the problem of exhaustion, a self-renewal hash chain based on Benaloh-Leichter secret sharing scheme (SRHC-BL SSS is designed, which can prolong the lifetime of network. Moreover, by introducing the queue theory model, we demonstrate that our scheme has much lower key consumption than μTESLA through simulation evaluations. Finally, we analyze and prove the security and efficiency of the proposed self-renewal hash chain, comparing with other typical schemes.

  10. Predicting the Number of Public Computer Terminals Needed for an On-Line Catalog: A Queuing Theory Approach.

    Science.gov (United States)

    Knox, A. Whitney; Miller, Bruce A.

    1980-01-01

    Describes a method for estimating the number of cathode ray tube terminals needed for public use of an online library catalog. Authors claim method could also be used to estimate needed numbers of microform readers for a computer output microform (COM) catalog. Formulae are included. (Author/JD)

  11. Design of queuing management system based on STC MCU%基于STC单片机的排队管理系统的设计

    Institute of Scientific and Technical Information of China (English)

    武一; 高超

    2012-01-01

    In order to improve the Service quality and work efficiency,to solve the dry and disordered queue problem,the system simulated the artificial process of calling number,using STC89C52 MCU control printer,LCD and voice chip to achieve the work that print,storage,display and broadcast line number.Furthermore,using MAX485 to extend RS-485 bus interface,that can achieve distributed serial communication.The system can meet the needs of casual queue and has many characteristics,such as low cost,small space occupation and better prospect.%为改善营业窗口的服务质量和工作效率,解决枯燥无序的排队问题,采用STC89C52单片机控制语音芯片、打印机、LCD显示屏来模拟人工叫号过程,完成号码的打印、存储、显示及播报工作;采用MAX485扩展RS-485总线接口,实现分布式串行通信。该系统能满足简单的排队需求,具有开发成本低,占用空间小等优点,有较好的市场应用前景。

  12. Queuing for coronary angiography during severe supply-demand mismatch in a US public hospital: analysis of a waiting list registry.

    Science.gov (United States)

    Rosanio, S; Tocchi, M; Cutler, D; Uretsky, B F; Stouffer, G A; deFilippi, C R; MacInerney, E J; Runge, S R; Aaron, J; Otero, J; Garg, S; Runge, M S

    1999-07-14

    Adverse cardiac events have been reported in patients waiting for either coronary surgery or angioplasty. However, data on the risk of adverse events while awaiting coronary angiography are limited, and none are available from a US population. To quantify cardiac outcomes in patients waiting for elective coronary angiography. Observational cohort study of 381 adult outpatients (mean [SD] age, 55 [12] years; 64% male; 61% white) on a waiting list for coronary angiography at a US tertiary care public teaching hospital during 1993-1994. Rates of cardiac death, nonfatal myocardial infarction, and hospitalizations for unstable angina or heart failure as a function of amount of time spent on a waiting list. Sixty-six patients were dropped from the waiting list but were included in the study analysis. During a mean (SD) follow-up of 8.4 (6.5) months, cardiac death, myocardial infarction, and hospitalization occurred in 6 (1.6%), 4 (1.0%), and 26 (6.8%) patients, respectively. The probability of events was minimal in the first 2 weeks and increased steadily between 3 and 13 weeks. By Cox multivariate analysis, 2 variables independently identified an increased risk of adverse events: a strongly positive treadmill exercise electrocardiogram or positive stress imaging result at referral (odds ratio [OR], 2.32; 95% confidence interval [CI], 1.22-4.16; P=.01) and the use of 2 to 3 anti-ischemic medications (OR, 1.98; 95% CI, 1.19-3.96; P=.04). Among 311 patients who ultimately underwent angiography, those with adverse events had a higher prevalence of coronary disease (96% vs 60%; P<.001), more frequently required revascularization (93% vs 53%; P<.001), and had longer hospital stays (mean [SD], 6.2 [4.3] vs 1.3 [0.7] days; P=.001). Our data suggest that in a cohort referred for coronary angiography, delaying the procedure places some patients at risk for death, myocardial infarction, unplanned hospitalization, a longer hospital stay, and, potentially, a poorer prognosis. Waits longer than 2 weeks should be avoided, and patients with strongly positive stress test results and those who require 2 to 3 anti-ischemic medications should be prioritized for early intervention.

  13. ANALYSIS OF THE ARBITRATION ALGORITHMS BASED ON SWITCHING FABRIC WITH VIRTUAL OUTPUT QUEUED%基于VOQ交换结构的仲裁算法分析

    Institute of Scientific and Technical Information of China (English)

    鄂大伟

    2002-01-01

    信头阻塞(HOL)限制了采用FIFO输入队列交换机的吞吐率,而使用虚输出队列(VOQ)技术可以完全消除HOL阻塞.给出了VOQ交换机模型,提出了对VOQ仲裁算法的分类方法和评价指标,分析了基于VOQ交换结构的MSM和MWM近似算法,并对其性能进行了分析比较.

  14. ELIMINATING HOL BLOCKING WITHMULTIPLE FIFO INPUT- BUFFERED QUEUED%用多FIFO输入缓冲队列消除HOL阻塞

    Institute of Scientific and Technical Information of China (English)

    鄂大伟

    2001-01-01

    对于输入端口具有单输入FIFO(先入先出)队列的输入缓冲信元交换机(如ATM),影响交换吞吐率的主要因素是信头阻塞(HOL).本文分析了在单FIFO队列情况下的信元阻塞的原因及解决办法,给出了输入端口具有多FIFO队列的信元交换结构,描述了基于NFIFO输入缓冲的排队策略和迭代匹配算法,并对它们的性能进行了分析.

  15. 基于消息队列遥测传输的推送系统%Push System Based on Message Queuing Telemetry Transport

    Institute of Scientific and Technical Information of China (English)

    姜妮; 张宇; 赵志军

    2015-01-01

    现有消息推送系统存在安全漏洞、个性化智能推送不足等问题.为此,基于消息队列遥测传输(MQTT)技术,提出一种消息推送系统,采用轻量的MQTT协议实现消息推送,包括安全认证和多样化智能推送设计,既能保证系统安全,又能根据用户个性化需求和消息传递性能要求,智能选择合理的消息发送方式和消息通信模式.测试结果表明该系统推送成功率高,消息发送和接收时间短.

  16. Streams of events and performance of queuing systems: The basic anatomy of arrival/departure processes, when the focus is set on autocorrelation

    DEFF Research Database (Denmark)

    Nielsen, Erland Hejn

    2004-01-01

    some arrival processes for some simulation study a thorough preliminary analysis has to be undertaken in order to uncover the basic time series nature of the interacting processes. Flexible methods for generating streams of autocorrelated variates of any desired distributional type, such as the ARTA...... method or some autocorrelation extended descriptive sampling method, can then easily be applied. The results from the Livny, Melamed and Tsiolis (1993) study as well as the results from this work both indicates that system performance measures as for instance average waiting time or average time...

  17. Performance Improvement of Embedded Web System Based on Queuing Theory%基于排队论的嵌入式Web系统性能优化

    Institute of Scientific and Technical Information of China (English)

    习博; 方彦军

    2007-01-01

    以嵌入式Web技术的广泛应用为背景,探讨了一种在嵌入式Web系统中,利用单服务窗等待式M/M/1排队理论,建立嵌入式Web系统性能评估模型的方法.就如何利用该模型对ARM+uCLinux实现的嵌入式Web系统进行网络性能评估,对嵌入式Web服务器的改进设计等问题进行了描述.

  18. Green Supply Chain Management Using the Queuing Theory to Handle Congestion and Reduce Energy Consumption and Emissions From Supply Chain Transportation Fleet

    OpenAIRE

    Arvin Aziziankohan; Fariborz Jolai; Mohammad Khalilzadeh; Roya Soltani; Reza Tavakkoli-Moghaddam

    2017-01-01

    Purpose: Nowadays, governments and people pay more attention to use green products due to environmental pollution, irreplaceable energy and shortage of resources. Green products are resulted from the application of green supply chain management strategies to the organizations' performance strategies, so that we can reduce environmental pollutants and wastes and take a step towards saving energy with limited resources. Methodology:  In this paper, the effect of reducing energy consumption ...

  19. 基于Edmonds-Karp算法的输入排队调度%Input-queued Crossbar Scheduling Based on Edmonds-Karp Algorithm

    Institute of Scientific and Technical Information of China (English)

    法拉

    2005-01-01

    输入排队Crossbar调度算法是以获得交换机的输入端口和输出端口最大匹配,从而得到高吞吐量为目的.因而在调度算法理论研究中把应用了二部图最大匹配的Maximum Size Matching和 Maximum Weight Matching算法作为目前各种调度算法性能评价标准.Edmonds-Karp算法是图论中求解网络最大流的经典算法之一.该文介绍了如何使用Edmonds-Karp算法求解二部图的最大匹配问题,并且应用算法于输入排队调度算法仿真中,得出经典MSM和MWM算法的性能仿真曲线,为进一步研究调度算法打下了理论基础.

  20. Streams of events and performance of queuing systems: The basic anatomy of arrival/departure processes, when the focus is set on autocorrelation

    DEFF Research Database (Denmark)

    Nielsen, Erland Hejn

    2004-01-01

    significant nature or (2) aggregate system behaviour is in general very different from just the summing-up (even for finite sets of micro-behavioural patterns) and/or (3) it is simply a wrong assumption that in many cases is chosen by mere convention or plain convenience. It is evident that before choosing...... some arrival processes for some simulation study a thorough preliminary analysis has to be undertaken in order to uncover the basic time series nature of the interacting processes. Flexible methods for generating streams of autocorrelated variates of any desired distributional type, such as the ARTA...

  1. Study on Planning of Inbound Tally Area Based on Queuing Theory%基于排队论的入库理货区规划研究

    Institute of Scientific and Technical Information of China (English)

    于占泉; 鲁晓春; 付近近

    2013-01-01

    把排队论的原理应用于仓库入库理货区规划研究,建立了入库理货区规划模型;用蒙特卡洛模拟来进行大量的数据分析,减弱随机性对结果造成的影响.结果显示利用排队论原理来规划仓库入库理货区面积,可以使得理货区的利用率达到71.2%,证明该种方法是合理有效的.

  2. A Scheduling Algorithm for Input-queued Crossbar%一种基于输入缓冲交叉开关的调度算法

    Institute of Scientific and Technical Information of China (English)

    宣二勇; 王蕴珠

    2010-01-01

    研究了交叉(Crossbar)开关的架构和缓冲策略.在已有的循环优先级多次匹配(RRM)算法和指针滑动多次迭代循环优先级匹配(iSLIP)算法的基础上提出了一种基于优先级列表的轮询调度(PB-RRM2)算法,该算法每次迭代只需要2步,减少了算法的调度时间,提高了Crossbar开关的运行速度.同时采用优先级列表的轮询(Round Robin)指针修改方式消除了指针的同步,提高了吞吐量.理论分析和仿真试验表明,算法在吞吐量和平均信元时延方面与iSLIP算法相当.

  3. Pointer Strategy Optimized Scheduling Algorithm for Input Queued Switches%一种优化指针策略的输入排队调度算法

    Institute of Scientific and Technical Information of China (English)

    申宁; 李俊; 倪宏

    2010-01-01

    针对FIRM(fcfs in round-robin matching)算法在处理非均匀业务时,延时和丢包性能出现缺陷的问题,在FIRM算法的基础上设计并实现了一种优化指针策略的low-FIRM(longest oldest weighted FIRM)算法.该算法根据队列长度和队首信元等待时间的权值修改输入端口的轮询指针,使得权值大的队列趋于优先服务,从而优化了在非均匀业务下的调度性能.接着给出了low-FIRM算法的性能分析和仿真,与iSLIP(iterative round-robin matching with slip)算法、FIRM算法进行了比较.仿真结果表明,low-FIRM与经典算法相比,在均匀业务下的性能近似,而在非均匀业务下性能有了较大的提升.

  4. 基于云平台SLA监视的混合制排队系统%A Mixed Queuing System of SLA Monitoring Based on Cloud Platform

    Institute of Scientific and Technical Information of China (English)

    孙亮; 陈宏伟

    2016-01-01

    云平台SLA监视是云服务代理中的一个重要功能.云平台SLA监视涉及三个角色,即云用户、云服务代理和云市场,并由云服务代理完成最终实现云平台的SLA监视功能.在这种情况下,应用排队论来实现SLA监视,本文将提出适合SLA监视的排队系统,研究用于云平台SLA监视的混合制排队系统,最终实现云用户排队和云服务代理处理.

  5. Queuing Machine Used in Bank Service Management%银行排队机在金融管理中的应用

    Institute of Scientific and Technical Information of China (English)

    深圳市来邦电子有限公司

    2003-01-01

    @@ 1引述 行为科学家发现:无序排队是导致客户流失的一条主要原因.研究结果表明:等候超过10分钟,情绪开始急躁;超过20分钟,情绪表现厌烦;超过40分钟,常因恼火而离去,而其中如出现"加塞"、"插队"现象,情况还将更加糟糕.

  6. System of vehicular dynamic spectrum access via queuing theory%基于排队论的车辆动态频谱接入系统研究

    Institute of Scientific and Technical Information of China (English)

    张伟; 刘南杰; 赵海涛

    2014-01-01

    This paper discusses dynamic spectrum access technology in the area of vehicular communication network , proposing a model of vehicular dynamic spectrum access over vacant TV channels. This model divides the communication needs of users for emergency and general service requests, and constructs the Markov chain model to analysis the service processes of them. As a result, an analytical model to meet different needs is constructed. The simulation results show that there is a significant reduction in the average queue waiting time with the increases number of available channels, and the average waiting time and queue length of the emergency service requests are far smaller than the general service requests.%将动态频谱接入技术引入到车辆通信网络中,提出了一种使用空闲广播电视信道进行车辆动态频谱接入的模型。该模型将用户通信需求分为紧急和普通服务请求,构建马尔科夫链分析其服务过程,得到了能够满足不同需求的分析模型。仿真结果表明,该模型能准确分析车辆动态频谱接入的过程,当空闲信道数增加时平均等待时间减少,紧急服务请求的平均等待时间和平均队列长度都远小于普通服务请求。

  7. The Analysis of the Queuing System Mx/Gn/1%关于Mx/Gn/1排队系统的分析

    Institute of Scientific and Technical Information of China (English)

    侯玉梅

    2001-01-01

    By means of imbedded Markov chain,we considered the M/Gn/l system in which the service time depends on the system size.We obtained the P.G.F.of the stationary system size and showed the conclusion is correct.%利用嵌入马尔可夫链法研究了M/Gn/l排队系统,求得了Mk/Gn/l系统的稳态队长的母函数,并验证了该结果的正确性。

  8. 基于仿真的可重入排队网络灵敏度分析%Simulation Based Sensitivity Analysis of Re-entrant Queuing Networks

    Institute of Scientific and Technical Information of China (English)

    王利存; 郑应平

    2001-01-01

    Based on the Poisson equation of Markov chain, the formula of derivatives of system performance with respect to system parameters is presented. Corresponding algorithm to estimate the derivatives is given. Then, Markov models of some re-entrant manufacturing systems are established. After simulating single sample paths of these models, the sensitivity of system performance to parameters of these re-entrant manufacturing systems is investiguted. The robustness of some priority scheduling policies is analyzed. Simulation results demonstrate the practicality and efficiency of the algorithm.%由马尔可夫链的Poisson方程推导了系统平均费用型品质指标对参数的导数公式,并给出了相应的估计算法。对可重入排队系统建立马尔可夫模型,通过仿真单个样本轨迹,应用给出的算法求出系统品质对参数的灵敏度,并分析了某些优先级调度策略的鲁棒性。仿真结果证明了该算法的实用性和有效性。

  9. 医院门诊药房Markov链排队模型研究%Research on Markov Chain Queuing Model in Hospital Outpatient Pharmacy

    Institute of Scientific and Technical Information of China (English)

    艾育华; 刘一强; 严静东

    2009-01-01

    随着国家医药卫生体制改革的推进,提高医疗卫生运行效率、服务水平和质量,成为医院改革的目标.对于医院中"常排队、排长队"的现象,特别是针对医院门诊就医最后一个环节门诊药房窗口,尝试利用医院信息化的数据与排队论相结合,研究适合于医院门诊药房的排队模型,探索医院该环节的工作效率与流程问题.

  10. Green supply chain management using the queuing theory to handle congestion and reduce energy consumption and emissions from supply chain transportation fleet

    National Research Council Canada - National Science Library

    Arvin Aziziankohan; Fariborz Jolai; Mohammad Khalilzadeh; Roya Soltani; Reza Tavakkoli-Moghaddam

    2017-01-01

    .... Green products are resulted from the application of green supply chain management strategies to the organizations' performance strategies, so that we can reduce environmental pollutants and wastes...

  11. Analysis of the algorithms for congestion management in computer networks

    Directory of Open Access Journals (Sweden)

    S. Szilágyi

    2013-06-01

    Full Text Available This paper presents one of the features of DS (Differentiated Services architecture, namely the queuing or congestion management. Packets can be placed into separate buffer queues, on the basis of the DS value. Several forwarding policies can be used to favor high priority packets in different ways. The major reason for queuing is that the router must hold the packet in its memory while the outgoing interface is busy with sending another packet. Our main goal is to compare the performance of the following queuing mechanisms: FIFO (First- In First-Out, CQ (Custom Queuing, PQ (Priority Queuing, WFQ (Weighted Fair Queuing, CBWFQ (Class Based Weighted Fair Queuing and LLQ (Low Latency Queuing.

  12. The Effects of Different Congestion Management Algorithms over Voip Performance

    Directory of Open Access Journals (Sweden)

    Szabolcs Szilágyi

    2015-02-01

    Full Text Available This paper presents one of the features of DS (Differentiated Services architecture, namely the queuing or congestion management. Packets can be placed into separate buffer queues, on the basis of the DS value. Several forwarding policies can be used to favor high priority packets in different ways. The major reason for queuing is that the router must hold the packet in its memory while the outgoing interface is busy with sending another packet. The main goal is to compare the performance of the following queuing mechanisms using a laboratory environment: FIFO (First-In First-Out, CQ (Custom Queuing, PQ (Priority Queuing, WFQ (Weighted Fair Queuing, CBWFQ (Class Based Weighted Fair Queuing and LLQ (Low Latency Queuing. The research is empirical and qualitative, the results are useful both in infocommunication and in education.

  13. Очікування обслуговування та коефіцієнт використання в системі масового обслуговування марківського типу

    OpenAIRE

    2014-01-01

    In many cases two variables such as utilization ratio (relative characteristic) and queuing time (absolute characteristic) are enough to assess the efficiency of a queuing system. The literature contains formulas for calculating utilization and downtime ratios as constants.In the paper, queuing time and utilization ratio are obtained as a function of time. This allows to investigate them in dynamics.For the queuing system S, set as a Markov chain with continuous time and finite number of stat...

  14. A Maximum Expected Covering Problem for Locating and Dispatching Two Classes of Military Medical Evacuation Air Assets

    Science.gov (United States)

    2014-01-01

    Fulton’s papers also account for the stochastic nature of military medical systems, this paper is distinct because it leverages queuing theory to derive...incorporating a simulation model, this paper uses queuing theory and binary linear programming to model and examine military medical systems. There has...spatial queuing approximation model is derived to provide inputs to the BLP model, which thus reflects the underlying queuing dynamics of the system. We

  15. An Approximate Dynamic Programming Mode for Optimal MEDEVAC Dispatching

    Science.gov (United States)

    2015-03-26

    but also the queuing of calls via the Hypercube model. Silva & Serra (2008) expand upon covering problems by incorporating queuing theory as well as...casualty category is used as the reward function. We incorporate queuing in the model to allow multiple casualty events to occur and the decision to wait...different priorities: the priority queuing covering location problem. Journal of the Opera- tional Research Society, 59(9), 1229–1238. Spurgeon, Neel. 1991

  16. The Analysis on Translation System Based on Asymmetric Cyclic Polling

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By the imbedded Markov chain theory and the probability generating function method, this paper discusses the queuing model of the switch node at the router and analyzes the derivative characters of first and second order of discrete asymmetric tri-queuing gate polling system. The average waiting time and the average queuing length are explicitly obtained and these results are verified by simulation.

  17. THE RESEARCH ON DISTRIBUTED PACKET SCHEDULING METHOD FOR AN INPUT AND OUTPUT QUEUING SWITCH%一种输入输出排队交换机中分布式分组调度方法的研究

    Institute of Scientific and Technical Information of China (English)

    涂晓东; 李乐民

    2003-01-01

    针对采用共享缓存(shared memory)做为交换机构(switching fabric)的输入输出排队交换机,该文给出了一个分布式分组调度方法DHIOS(Distributed Hierarchical Ingress and OutputScheduling)并做了详细的仿真.表明DHIOS可以支持变长分组,能够确保业务流的QoS,性能优良.

  18. Havalimanında Kuyruk Simülasyonu: İzmir-Gaziemir Adnan Menderes Havalimanı Uygulaması (Queuing Line Simulation in Airport: Application of İzmir Gaziemir Adnan Menderes Airport

    Directory of Open Access Journals (Sweden)

    Bülent TATAR

    2009-07-01

    Full Text Available 23rd International Universiade Olympic Games will be held in Izmir between July 6 and 16 and is the second largest organisation after World Olympic Games. Almost 8000 athletes from 170 different countries will attend to the games and a well organised airway transportation traffic is one of the major concerns. Thus optimization of the airway traffic is needed also because of the expected increase of the density of Adnan Menderes Airport due to continuing national air traffic. Waiting time optimization of the incoming and outgoing planes is a necessity. So it will be examined if a new landing field is need or not. In order to do this the most crowded day 08 30 2002 is selected as a reference and analysis has been carried. Data have been collected from the observation of 100 planes that had been used on the selected date.

  19. 信道保护策略在LEO卫星通信系统中的应用%Guard channel with queuing strategy in the LEO satellite communication system

    Institute of Scientific and Technical Information of China (English)

    吕智勇; 丁锐

    2005-01-01

    信道预留策略可以降低通信业务的中断概率,提高整个系统的性能.但由于在地面蜂窝通信系统中,小区业务量的变化较为复杂,使得该策略的应用十分困难.在此根据LEO卫星的特点,对信道预留策略加以改进,使其可以根据小区中业务量的大小动态的调整预留的信道数量,取得了良好的效果.此外,还采用了新到达业务排队策略,进一步提高了LEO卫星移动通信系统的整体性能.

  20. 基于Virtual Output Queued交换结构的最大权重匹配算法%The Maximu m Weight Matching Algorithms Based on Switching Fabric with Virtual Output Queued

    Institute of Scientific and Technical Information of China (English)

    鄂大伟

    2001-01-01

    信头阻塞(HOL)限制了采用FIFO输入队列交换机的吞吐率,而使用虚输出队列(VOQ)技术可以完全消除HOL阻塞.文章给出了VOQ的交换机模型,介绍了基于最大权重匹配的算法LQF、OCF、LPF及其性能,还描述了更加实用的并行迭代算法i-LQF、i- OCF和i-LPF.文章的结论对于构造高带宽的交换机具有实际意义.

  1. 模糊随机需求下应急救援中心排队选址模型及算法%Queuing location model and algorithm for emergency relief centers under fuzzy random demand

    Institute of Scientific and Technical Information of China (English)

    陈鑫; 汪传旭; 石刘红

    2011-01-01

    In order to solve the location problem of emergency relief centers, on the basis of assumption that demands from disaster areas are fuzzy random variable, and the factor that transportation speed changes with time is considered at the same time, a model for optimizing emergency relief center location is set up by combining location theory with queue theory. The model aims to achieve minimization of total transportation cost and guarantees response time. A hybrid intelligent algorithm which combines fuzzy random simulation with genetic algorithm is introduced to solve the proposed model. A numerical example is given to demonstrate the practicability of the model and effectiveness of the algorithm. Sensitivity analysis for the numerical example shows that the proposed algorithm is robust and the total relief cost rises with the increase of the number of disaster areas and relief centers as well as demand rates from disaster areas.%为解决应急救援中心的选址问题,在假定受灾点需求为模糊随机变量的基础上,考虑运输速度随时间的演变而变化,结合排队论和选址理论,建立带有响应时间承诺的以总运输成本最小为目标的应急救援中心选址优化模型,并结合模糊随机模拟和遗传算法提出求解上述模型的混合智能算法.通过算例验证模型的实用性和算法的有效性.通过对算例进行灵敏度分析得出:所提出的算法具有很好的鲁棒性;应急救援总成本随着受灾点数量、救援中心的个数和各受灾点需求发生率的增加而上升.

  2. Research on Capacity of Locks on the Grand Canal With Queuing Theory%基于排队理论的京杭运河船闸通过能力研究

    Institute of Scientific and Technical Information of China (English)

    黄海鸥; 张玮; 李骁春

    2009-01-01

    通过对船闸营运方式的调查,结合苏北部分船闸的营运情况,将排队服务系统模型研究方法引入船闸系统的研究中,建立带有两个顾客等级的M/G/K服务系统排队模型,通过模型的求解,得出船队过闸等待时间、船舶排队长度等与船闸服务能力的关系,在此基础上分析了到船的随机性对船闸最大通过量的影响情况,并引出船闸基本通过能力的计算方法.

  3. GENETIC ALGORITHM AND QUEUING NETWORK BASED CARD NUMBER DETERMINATION METHOD FOR SERIAL CONWIP SYSTEM%基于遗传算法和排队网的串联CONWIP系统流通卡数的确定方法

    Institute of Scientific and Technical Information of China (English)

    黄敏; 汪定伟

    2002-01-01

    在CONWIP(constant work in process)系统中,流通卡数是系统有效运行的关键因素.文中针对串联CONWIP系统,提出了非线性整数规划模型和排队网模型相结合的问题描述模型,以及遗传算法与排队网络分析相结合的问题求解算法.实例仿真验证了该方法的有效性.

  4. 时隙间迭代的输入队列交换机Round-Robin调度算法%A Round-Robin Scheduling Algorithm by Iterating Between Slots for Input- Queued Switches

    Institute of Scientific and Technical Information of China (English)

    吴俊; 陈晴; 罗军舟

    2005-01-01

    输入队列因具有良好的可扩展性而广泛应用于高速交换机和路由器中,但输入队列需要精心设计调度算法以获取较好的性能.Round-Robin算法因其简单性和并行性而得到广泛的研究,但现有的Round-Robin算法在突发流量和非均匀流量下的负荷-延迟性能较差.提出了调度决策在时隙间进行迭代的思想,并利用队列长度具有随机性的特点设计了能近似最大匹配的Round-Robin算法--iSLOT.仿真结果表明,iSLOT不仅在均匀流量下是稳定的,在非均匀流量和突发流量下的吞吐率及延迟性能均远好于现有的Round-Robin算法.

  5. iRSDRR:一种全异步的基于输入排队Crossbar交换结构的调度算法%iRSDRR:A Fully Desynchronized Scheduling Algorithm for Input Queued Crossbar Switching Fabric

    Institute of Scientific and Technical Information of China (English)

    严敬; 邱智亮; 杨君刚

    2005-01-01

    DRR(Dual Round-Robin)[1]调度算法是一种公平、高效、硬件实现简单的基于输入排队Crossbar交换结构的信元调度算法.为了进一步改善这种算法的性能,该文提出了一种全异步的多次迭代DRR算法,即iRSDRR(iterative Rotating Static Dual Round-Robin).该算法在开始时,将所有的输入、输出仲裁器的指针全部设置为异步的,以后每个时隙静态地更新所有的仲裁器的指针.仿真结果表明该算法在不同业务流条件下的性能都优于DRR调度算法.

  6. 多业务网络中一种新队列调度算法的研究%A new queuing scheduling algorithm for multi-service network

    Institute of Scientific and Technical Information of China (English)

    张春风; 钱学荣

    2015-01-01

    In this paper, an improved algorithm was proposed based on the traditional weighted round robin algorithm, the strict priority scheduling algorithm and the token bucket mechanism. In coexistence of multi-service network , this algorithm can guarantee the QoS (Quality of Service) requirements of different types of traffic. Mean while, when the traffic changes, the algorithm can adjust the bandwidth corresponding service dynamically, and does not affect the high priority queue. Simulation results show that the algorithm can adapt to the changes in the network within a certain range, and the algorithm can alleviate the problem of packet loss caused by burst traffic effectively, improving network performance greatly.%在传统加权轮询调度算法和严格优先级调度算法的基础上,加入令牌桶机制,实现了一种改进算法。在多业务并存网络中,该算法能够对不同等级的业务实现不同的 QoS (服务质量),同时,在业务流量发生变化时,能够动态调整相应业务的带宽,且不会对高优先级队列造成影响。仿真实验表明,该算法可以在一定范围内适应网络的变化,有效缓解了突发流量所造成的报文丢包问题,大大提高了网络性能。

  7. The Lattice Path for Embedded Markov Chain of M/M/1 Queuing System%M/M/1排队系统嵌入Markov链瞬态解的格路径算法

    Institute of Scientific and Technical Information of China (English)

    刘海宁; 屈明双

    2009-01-01

    在定义了生灭过程状态转移的单格与升降格和降升格的基础上,证明了M/M/1排队系统{X(t)t≥0}的嵌入Markov链{X(n)n≥0}的转移概率弱收敛于系统的瞬态解,并利用随机游动的格路径算法求出了该链的转移概率P(i,j,n)的显式算法表达式,从而达到确定M/M/1排队系统{X(t)t≥0}瞬态解的转移概率的目的.

  8. Markov Chain Queuing Model for Signalized Intersections with Stochastic Vehicle Arrivals%随机到达车辆信号交叉路口的Markov链排队模型

    Institute of Scientific and Technical Information of China (English)

    蒋阳升; 胡路; 蒲云

    2010-01-01

    为了克服现有交叉口排队分析模型中车流到达均服从特定规律这一假定的局限性,用嵌入马尔科夫链技术建立了定周期信号交叉口车辆随机到达的Markov链排队模型,在Excel环境下嵌入LINGO软件,编写了相应的模型程序和用于验证模型的仿真模拟程序.算例表明: 本文模型计算的平均排队长度与实际调查结果很接近,与随机模拟结果的误差为0.14%;在50%~65%分位范围内,用Markov链排队模型计算的排队长度与实际样本结果和随机模拟结果相同,在其他分位最大相对误差为3.85%.

  9. Research on Replacement Model for Queuing System with Deteriorative Repairable Service Station Including Delay Repair%带延迟修理的退化服务台排队系统更换模型研究

    Institute of Scientific and Technical Information of China (English)

    贾积身; 侯江华

    2011-01-01

    针对带有延迟修理的退化可修服务台的排队系统,提出了一种新的维修更换模型。假定服务台逐次故障后的维修时间构成随机递增的几何过程,工作时间构成随机递增的几何过程,在服务台每次故障以概率P需要延迟修理和延迟修理时间为随机变量的情况下,选取被服务的顾客数N为其更换策略,以系统长期运行单位时间内的期望效益为目标函数,通过更新过程和几何过程理论建立数学模型,导出了目标函数的解析表达式。并根据目标函数情况,通过最大化目标函数来获取系统最优的更换策略N^*,最后还对结果进行了讨论。%To study queueing system with deteriorative repairable service station including delay repair, this paper proposes a kind of new maintenance and replacement model. Supposing that the successive survival time of the system constitute a decreasing geometric process stochastically, while the consecutive repair time of the system constitute an increasing geometric process, under the conditions that the delay repair time is random variable and the failure service station needs delay repair with probability , we take the number N of the customer that have been serv- iced at the service station as its replacement policy and choose the long - run expected profit per unit time as objec- tive function. By using renewal process and geometric process theory, mathematic model is established and the ex- plicit expressions of the objective function is derived. According objective function, the optimal replacement policy is obtained by maximizing the objective function. Finally, we discuss the result also.

  10. The dynamics of urban traffic congestion and the price of parking

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; de Palma, André

    2013-01-01

    We consider commuting in a congested urban area. While an efficient time-varying toll may eliminate queuing, a toll may not be politically feasible. We study the benefit of a substitute: a parking fee at the workplace. An optimal time-varying parking fee is charged at zero rate when...... there is queuing and eliminates queuing when the rate is non-zero. Within certain limits, inability to charge some drivers for parking does not reduce the potential welfare gain. Drivers who cannot be charged travel when there is queuing. In some cases, interaction between morning and evening commutes can...

  11. Optimal queue-size scaling in switched networks

    NARCIS (Netherlands)

    Shah, D.; Walton, N.S.; Zhong, Y.J.

    2014-01-01

    We consider a switched (queuing) network in which there are constraints on which queues may be served simultaneously; such networks have been used to effectively model input-queued switches and wireless networks. The scheduling policy for such a network specifies which queues to serve at any point i

  12. Performance Approximation and Design of Pick-and-Pass Order Picking Systems

    NARCIS (Netherlands)

    M. Yu (Mengfei); M.B.M. de Koster (René)

    2007-01-01

    textabstractIn this paper, we discuss an approximation method based on G/G/m queuing network modeling using Whitt’s (1983) queuing network analyzer to analyze pick-and-pass order picking systems. The objective of this approximation method is to provide an instrument for obtaining rapid performance

  13. 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.

  14. Working memory capacity and dual-task interference in picture naming

    NARCIS (Netherlands)

    Piai, V.; Roelofs, A.P.A.

    2013-01-01

    Researchers have found no agreement on whether dual-task interference in language performance, such as dual-task interference from tone discrimination on picture naming, reflects passive queuing or active scheduling of processes for each task. According to a passive-queuing account, while a central

  15. Tutorial in medical decision modeling incorporating waiting lines and queues using discrete event simulation.

    Science.gov (United States)

    Jahn, Beate; Theurl, Engelbert; Siebert, Uwe; Pfeiffer, Karl-Peter

    2010-01-01

    In most decision-analytic models in health care, it is assumed that there is treatment without delay and availability of all required resources. Therefore, waiting times caused by limited resources and their impact on treatment effects and costs often remain unconsidered. Queuing theory enables mathematical analysis and the derivation of several performance measures of queuing systems. Nevertheless, an analytical approach with closed formulas is not always possible. Therefore, simulation techniques are used to evaluate systems that include queuing or waiting, for example, discrete event simulation. To include queuing in decision-analytic models requires a basic knowledge of queuing theory and of the underlying interrelationships. This tutorial introduces queuing theory. Analysts and decision-makers get an understanding of queue characteristics, modeling features, and its strength. Conceptual issues are covered, but the emphasis is on practical issues like modeling the arrival of patients. The treatment of coronary artery disease with percutaneous coronary intervention including stent placement serves as an illustrative queuing example. Discrete event simulation is applied to explicitly model resource capacities, to incorporate waiting lines and queues in the decision-analytic modeling example.

  16. Design of an IPTV Multicast System for Internet Backbone Networks

    OpenAIRE

    T. H. Szymanski; Gilbert, D

    2010-01-01

    The design of an IPTV multicast system for the Internet backbone network is presented and explored through extensive simulations. In the proposed system, a resource reservation algorithm such as RSVP, IntServ, or DiffServ is used to reserve resources (i.e., bandwidth and buffer space) in each router in an IP multicast tree. Each router uses an Input-Queued, Output-Queued, or Crosspoint-Queued switch architecture with unity speedup. A recently proposed Recursive Fair Stochastic Matrix Decompos...

  17. Switching Processes in Queueing Models

    CERN Document Server

    Anisimov, Vladimir V

    2008-01-01

    Switching processes, invented by the author in 1977, is the main tool used in the investigation of traffic problems from automotive to telecommunications. The title provides a new approach to low traffic problems based on the analysis of flows of rare events and queuing models. In the case of fast switching, averaging principle and diffusion approximation results are proved and applied to the investigation of transient phenomena for wide classes of overloading queuing networks.  The book is devoted to developing the asymptotic theory for the class of switching queuing models which covers  mode

  18. The Analysis and Comparison of Iterative matching Arbitration Algorithm for Switching Fabrics with Multiple FIFO Input Queued%基于多FIFO输入队列交换结构的迭代匹配算法性能分析与比较

    Institute of Scientific and Technical Information of China (English)

    鄂大伟

    2001-01-01

    对于输入端口具有单FIF0(先入先出)队列的输入缓冲交换机(如ATM),影响交换吞吐率的主要因素是信头阻塞(HOL).文章给出了输入端口具有多FIFOl队列的信元交换机结构,阐述了PIM、iSLIP、iLRU、iLQF等多种迭代匹配算法,并对它们的性能进行了分析和比较.

  19. Efecto del uso de tiempos de atención heavy-tailed sobre el modelo básico de líneas de espera y sus medidas de desempeño The consequences of heavy-tailed service time distribution on a basic queuing model and its performance indicators

    Directory of Open Access Journals (Sweden)

    Rangel Martínez Lina M.

    2010-08-01

    Full Text Available La reciente aparición de modelos generatrices de líneas de espera con tiempos de atención heavy-tailed y su comprobación empírica implican la necesidad de conocer el comportamiento de las medidas clásicas de desempeño de una línea de espera bajo estas condiciones. El objetivo del estudio fue el de analizar el comportamiento de Lq (longitud promedio de la fila y Wq (tiempo promedio de espera en fila variando los parámetros capacidad del sistema, nivel de utilización promedio ( ρ y número de servidores para líneas de espera con tiempos de atención heavy-tailed, y contrastar dicho comportamiento con los resultados clásicos basados en procesos de Poisson, usando para ello la simulación de eventos discretos. Los resultados mostraron que la sensibilidad de los modelos con tiempos de atención heavy-tailed a variaciones en los parámetros es mayor que la de los modelos basados en procesos de Poisson. En particular, a partir de capacidades de sistema de 1.000 entidades ciertos procesos heay-tailed pueden considerarse infinitos, y la importancia del número de servidores es mayor en los procesos heavy-tailed analizados que en los procesos de Poisson. Por último, la utilización de Lq y Wq como medidas de desempeño es inadecuada para tiempos de atención heavy-tailed al generar resultados inestables y contraintuitivos.Recent research showing theoretical generative models for heavy-tailed service time queues and its empirical validation implies the need for a better knowledge of the key performance indicators’ behavior under such assumption. The behavior of the average length of the queue ( and the average waiting-time (Wq were analyzed through simulation, varying system capacity, average service utilization factor ( ρ and the number of servers in the systems as parameters. Comparisons were also made with service times based on Poisson processes. The results showed more sensitive variations of Lq and Wq for heavy-tailed service times than for Poisson-based service times. Systems having a capacity of over 1,000 entities might be considered as being systems having infinity capacity and the number of servers has a greater importance in heavy-tailed ruled processes than in Poisson processes. There was a lack of adequacy of Lq and Wq as key performance indicators for heavy-tailed service times, lea- ding to unexpected and unstable results.

  20. Integrating Unmanned Aerial Vehicles into Surveillance Systems in Complex Maritime Environments

    Science.gov (United States)

    2013-09-01

    These methods may involve algebra, calculus , probability theory, linear programming, decision analysis, Markov chain analysis and queuing theory... Pearson Addison Wesley. Dickerson, L. (2007). UAVs on the rise: Global investment in unmanned systems quickens. Aviation Week & Space Technology

  1. International Journal of Science and Technology (STECH) Bahir Dar ...

    African Journals Online (AJOL)

    Nneka Umera-Okeke

    in a queuing system are the customers (those demanding for service) and the servers. (those providing the ... cases where the discipline of service within each customer type is FCFS or LCFS. Mor ...... Supported by NSF career Grant CCR-.

  2. non -governmental organisations' response to substance abuse and ...

    African Journals Online (AJOL)

    User

    This research was undergirded by the human rights approach. .... other homeless people were queuing for food rations at the Anglican Cathedral. .... De Melo Resend, V. (2012) Critical discourse analysis and ethnography: The crisis in the.

  3. THE WORK SIMULATION OF FLOW RATE FOR CARRIAGES' REPAIR AS A MULTIPHASE, MULTIPLEX AND MULTIDISCIPLINARY SYSTEM OF MASS SERVICE

    Directory of Open Access Journals (Sweden)

    V. V. Myamlin

    2011-04-01

    Full Text Available The algorithm of computer simulation of the flexible flow for repair of cars as a multiphase polychannel manyobject queuing system is presented. The basic operators of the model are given and their work is described.

  4. Maximum Entropy Principle Based Estimation of Performance Distribution in Queueing Theory

    Science.gov (United States)

    He, Dayi; Li, Ran; Huang, Qi; Lei, Ping

    2014-01-01

    In related research on queuing systems, in order to determine the system state, there is a widespread practice to assume that the system is stable and that distributions of the customer arrival ratio and service ratio are known information. In this study, the queuing system is looked at as a black box without any assumptions on the distribution of the arrival and service ratios and only keeping the assumption on the stability of the queuing system. By applying the principle of maximum entropy, the performance distribution of queuing systems is derived from some easily accessible indexes, such as the capacity of the system, the mean number of customers in the system, and the mean utilization of the servers. Some special cases are modeled and their performance distributions are derived. Using the chi-square goodness of fit test, the accuracy and generality for practical purposes of the principle of maximum entropy approach is demonstrated. PMID:25207992

  5. Railway Network Timetabling and Dynamic Traffic Management

    NARCIS (Netherlands)

    Hansen, I.A.

    2009-01-01

    The paper discusses the current state of research concerning railway network timetabling and traffic management. Timetable effectiveness is governed by frequency, regularity, accurate running, recovery and layover times, as well as minimal headway, buffer times and waiting times. Analytic (queuing)

  6. Modeling Human Supervisory Control in Heterogeneous Unmanned Vehicle Systems

    Science.gov (United States)

    2009-02-01

    events through a queue, nominally due to another queue having reached its capacity limitation (Balsamo, Persone, & Onvural, 2001; Onvural, 1990; Perros ...Communication and Coordination, Athens, Greece. Perros , H. G. (1984). Queuing Networks with Blocking: A Bibliography. ACM Sigmetrics, Performance Evaluation

  7. Maximum entropy principle based estimation of performance distribution in queueing theory.

    Science.gov (United States)

    He, Dayi; Li, Ran; Huang, Qi; Lei, Ping

    2014-01-01

    In related research on queuing systems, in order to determine the system state, there is a widespread practice to assume that the system is stable and that distributions of the customer arrival ratio and service ratio are known information. In this study, the queuing system is looked at as a black box without any assumptions on the distribution of the arrival and service ratios and only keeping the assumption on the stability of the queuing system. By applying the principle of maximum entropy, the performance distribution of queuing systems is derived from some easily accessible indexes, such as the capacity of the system, the mean number of customers in the system, and the mean utilization of the servers. Some special cases are modeled and their performance distributions are derived. Using the chi-square goodness of fit test, the accuracy and generality for practical purposes of the principle of maximum entropy approach is demonstrated.

  8. Optimization

    CERN Document Server

    Pearce, Charles

    2009-01-01

    Focuses on mathematical structure, and on real-world applications. This book includes developments in several optimization-related topics such as decision theory, linear programming, turnpike theory, duality theory, convex analysis, and queuing theory.

  9. Maximum entropy principle based estimation of performance distribution in queueing theory.

    Directory of Open Access Journals (Sweden)

    Dayi He

    Full Text Available In related research on queuing systems, in order to determine the system state, there is a widespread practice to assume that the system is stable and that distributions of the customer arrival ratio and service ratio are known information. In this study, the queuing system is looked at as a black box without any assumptions on the distribution of the arrival and service ratios and only keeping the assumption on the stability of the queuing system. By applying the principle of maximum entropy, the performance distribution of queuing systems is derived from some easily accessible indexes, such as the capacity of the system, the mean number of customers in the system, and the mean utilization of the servers. Some special cases are modeled and their performance distributions are derived. Using the chi-square goodness of fit test, the accuracy and generality for practical purposes of the principle of maximum entropy approach is demonstrated.

  10. ECE6010 - Stochastic Processes, Spring 2006

    OpenAIRE

    Moon, Todd K.

    2006-01-01

    This course provides an introduction to stochastic processes in communications, signal processing, digital and computer systems, and control. Topics include continuous and discrete random processes, correlation and power spectral density, optimal filtering, Markov chains, and queuing theory. Technical Requirements: MATLAB

  11. Aspects of Information Feedback and Parameter Update Design for a Seismic Surveillance System

    Science.gov (United States)

    1974-12-31

    deployment (RSD) are collected by the data col- lection processor (DCP) and stored on the remote storage element ( RSE ). The USE is shared by the...detection bulletins, and other parameters and messages destined for central facility processing or storage are queued on the RSE for transmission to...central facility are queued on the RSE by the RCP for processing and use by DCP and SDP. The RSE furthermore holds Lha processing algorithm and

  12. Characterizing the Efficacy of the NRL Network Pump in Mitigating Covert Timing Channels

    Science.gov (United States)

    2012-02-01

    optimal causal coding-decoding problems,” http://arxiv.org/abs/1102.0250, 2010. [37] S. Gorantla and T. Coleman, “On reversible markov chains and...information by encoding it in the timings of the packets sent through a queuing system was investigated in [18]. In [19], the authors study an...adversarial queuing setup, where a jammer has control of the queueing discipline. Most recently Askarov et al. adapting the periodic quantization methodology

  13. Robust Analysis of the Joint Strike Fighter Integrated Training Center Pilot Scheduling

    Science.gov (United States)

    2011-09-01

    models weather using Markov chains and a weather resource, since weather conditions for consecutive events are not independent (Dummar, 2011). He...justification for procurement or as an explanation for bottlenecks in the system. The ITC model is a discrete-event, first-in first-out, queuing -based...Unfortunately, queuing theory tells us that this will likely bias the results (Ross, 2007). In robust analysis, the intent is to look at the effect of

  14. Parametric Estimation of Load for Air Force Data Centers

    Science.gov (United States)

    2015-03-27

    solution to the data center sizing problem. By analogy, Erlang’s formulae for the probability of blocking and queuing should be applicable to...number of phone calls made to a telephone switch, it has general applicability to many traffic engineering and queuing problems. This thesis will...Central Limit Theorem is a theory that states, convolution of a sufficiently large number of independent random variables will be approximately

  15. From Onions to Shallots: Rewarding Tor Relays with TEARS

    Science.gov (United States)

    2014-07-18

    12. Jakobsson, M.: Ripping coins for a fair exchange. In: Conference on the Theory and Applications of Cryptographic Techniques (EUROCRYPT) (1995) 13...proportions. Dovrolis et al. design a scheduler under the proportional differentiation model using a queuing delay metric [10], which in our case...corresponds to Tor cell waiting times. For class i, the quality metric qi combines the queuing delay Di(t) of the longest waiting cell with the long-term

  16. Performance Analysis of DiffServ based Quality of Service in a Multimedia Wired Network and VPN effect using OPNET

    Directory of Open Access Journals (Sweden)

    Muhammad Aamir

    2012-05-01

    Full Text Available Quality of Service (QoS techniques are applied in IP networks to utilize available network resources in the most efficient manner to minimize delays and delay variations (jitters in network traffic having multiple type of services. Multimedia services may include voice, video and database. Researchers have done considerable work on queuing disciplines to analyze and improve QoS performance in wired and wireless IP networks. This paper highlights QoS analysis in a wired IP network with more realistic enterprise modeling and presents simulation results of a few statistics not presented and discussed before. Four different applications are used i.e. FTP, Database, Voice over IP (VoIP and Video Conferencing (VC. Two major queuing disciplines are evaluated i.e. Priority Queuing and Weighted Fair Queuing for packet identification under Differentiated Services Code Point (DSCP. The simulation results show that WFQ has an edge over PQ in terms of queuing delays and jitters experienced by low priority services. For high priority traffic, dependency of Traffic Drop, Buffer Usage and Packet Delay Variation on selected buffer sizes is simulated and discussed to evaluate QoS deeper. In the end, it is also analyzed how networks database service with applied Quality of Service may be affected in terms of throughput (average rate of data receivedfor internal network users when the server is also accessed by external user(s through Virtual Private Network (VPN.

  17. MULTIPATH VIRTUAL QUEUE MANAGEMENT SYSTEM FOR EFFECTIVE PACKET SCHEDULING IN MPLS NETWORKS

    Directory of Open Access Journals (Sweden)

    V. Ramachandran

    2012-09-01

    Full Text Available With the rapid development of communication and networking technologies VOIP has become an alternate to traditional telephony. These applications prefer timeliness in packet delivery. To perform load balancing, link utilization and to minimize the packet loss rate Multipath virtual Queue Management System for Effective Packet Scheduling in MPLS networks is proposed. The VoIP flows are dispersed into multiple available label switched paths to perform load balancing and link utilization. Virtual queues are maintained in all output ports to avoid queuing delay and HOL blocking. The proposed system ensures the arrival order of all the packets and plays back in the order of transmission. The performance of the proposed Virtual queuing system is compared with single path CSFQ queuing system with no virtual queue and Simulation results are proposed to show theefficiency of the proposed system.

  18. Simulation of High-Level Way Toll Systemunder the Condition of Mixed Traffic Flow

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Parking-toll on main-line is one of toll models on high-level ways in our country at present. This paper analyzes the flow' s distributing function, queuing model, and vehicle passing time. Through computer simulation, the negative index relationships between carrying capacity and serving time, and the index relationships between the queuing delay and flow are gained under the condition of different serving time and different vehicle type composition. When the flow density is low, the vehicle type composing has less influence on system serving level. Contrarily, also. Disposing toll station by roadway where flow density is high, we can save transection areas of toll station, reduce system queuing delay time, and enhance carrying capacity of toll station.

  19. Modeling and performance analysis of QoS data

    Science.gov (United States)

    Strzeciwilk, Dariusz; Zuberek, Włodzimierz M.

    2016-09-01

    The article presents the results of modeling and analysis of data transmission performance on systems that support quality of service. Models are designed and tested, taking into account multiservice network architecture, i.e. supporting the transmission of data related to different classes of traffic. Studied were mechanisms of traffic shaping systems, which are based on the Priority Queuing with an integrated source of data and the various sources of data that is generated. Discussed were the basic problems of the architecture supporting QoS and queuing systems. Designed and built were models based on Petri nets, supported by temporal logics. The use of simulation tools was to verify the mechanisms of shaping traffic with the applied queuing algorithms. It is shown that temporal models of Petri nets can be effectively used in the modeling and analysis of the performance of computer networks.

  20. Queueing model for an ATM multiplexer with unequal input/output link capacities

    Science.gov (United States)

    Long, Y. H.; Ho, T. K.; Rad, A. B.; Lam, S. P. S.

    1998-10-01

    We present a queuing model for an ATM multiplexer with unequal input/output link capacities in this paper. This model can be used to analyze the buffer behaviors of an ATM multiplexer which multiplexes low speed input links into a high speed output link. For this queuing mode, we assume that the input and output slot times are not equal, this is quite different from most analysis of discrete-time queues for ATM multiplexer/switch. In the queuing analysis, we adopt a correlated arrival process represented by the Discrete-time Batch Markovian Arrival Process. The analysis is based upon M/G/1 type queue technique which enables easy numerical computation. Queue length distributions observed at different epochs and queue length distribution seen by an arbitrary arrival cell when it enters the buffer are given.

  1. Performance measurements of single server fuzzy queues with unreliable server using left and right method

    Science.gov (United States)

    Mueen, Zeina; Ramli, Razamin; Zaibidi, Nerda Zura

    2015-12-01

    There are a number of real life systems that can be described as a queuing system, and this paper presents a queuing system model applied in a manufacturing system example. The queuing model considered is depicted in a fuzzy environment with retrial queues and unreliable server. The stability condition state of this model is investigated and the performance measurement is obtained by adopting the left and right method. The new approach adopted in this study merges the existing α-cut interval and nonlinear programming techniques and a numerical example was considered to explain the methodology of this technique. From the numerical example, the flexibility of the method was shown graphically showing the exact real mean value of customers in the system and also the expected waiting times.

  2. Development of machine interference system in industries

    Directory of Open Access Journals (Sweden)

    Rodina Veronika Igorevna

    2013-09-01

    Full Text Available The aim of this work is to improve the control effectiveness of cell-type system due to solving the problem of optimal allocation of labor force. An optimality criterion was created as a result of this work. It allows to characterize the operation of the system and choose the best option of its organization which has maximized output. The main sections of the work: 1 The main directions of queuing theory in the analysis of production processes; 2 Optimality criterion in the production task of queuing; 3 Determination of the optimal number of operators in production units.

  3. ANALYSIS OF MULTI-SERVER SINGLE QUEUE

    OpenAIRE

    2011-01-01

    Queuing properties such as expected total service time and its variance and some performance measures like the expected number of phases in the system, expected number of phases in the queue, expected number of customers in the queue, expected waiting time in the queue and in the system as well as the number of customers in the system have been derived for an  M/Ek/s: ( /FCFS) queuing model with k identified stages in series, each with average service time of . Also, numerical illustrati...

  4. 光分组交换节点中串扰特性的研究%Study of Crosstalk Property in an Optical Packet Switching Node

    Institute of Scientific and Technical Information of China (English)

    王春华; 李力; 贾潞华; 黄肇明

    2002-01-01

    The effect of queuing delay of output buffer on the crosstalk property in optical packet switching nodes is investigated. The relationship between crosstalk and buffer length is obtained. From the calculation and simulation results, it is concluded that the crosstalk power penalty predominantly depends on the buffer length, the longer the buffer, the greater the penalty, as well as the random range of the penalty. While comparing with the effect of queuing delay, the effect of random routing path delay takes very little proportion in the total power penalty.

  5. Study of Crosstalk propoerty in an Optical Packet Switching Node

    Institute of Scientific and Technical Information of China (English)

    王春华; 李力; 等

    2002-01-01

    The effect of queuing delay of output buffer on the crosstalk property in optical packel switching nodes in investigated.The relationship between crosstalk and buffer length is obtained.From the calculation and simulation results,it is concluded that the corsstalk power penalty predominantly depends on the buffer length,the longer the buffer,the greater the penalty,as well as the random range of the penalty.While comparing with the effect of queuing delay,the effect of random routing path delay takes very little proportion in the total power penalty.

  6. ANALYSIS OF MULTI-SERVER SINGLE QUEUE

    Directory of Open Access Journals (Sweden)

    Emmanuel John Ekpenyong

    2011-04-01

    Full Text Available Queuing properties such as expected total service time and its variance and some performance measures like the expected number of phases in the system, expected number of phases in the queue, expected number of customers in the queue, expected waiting time in the queue and in the system as well as the number of customers in the system have been derived for an  M/Ek/s: ( /FCFS queuing model with k identified stages in series, each with average service time of . Also, numerical illustrations have also been used to illustrate the results.

  7. An Optimal Capacity Planning Model for General Cargo Seaport

    Directory of Open Access Journals (Sweden)

    Čedomir Dundović

    2012-10-01

    Full Text Available In this paper the application of the queuing the01y in optimalcapacity planning for general cargo seaport is presented.The seaport as a queuing syslem is defined and tlws, on the basisof the arrival and serviced number of ships in an obsen•edtime unit, the appropriate operating indicators of a port systemare calculated. Using the model of total port costs, the munberof berths and cranes on the berth can be determined wherebythe optimal port system functioning is achieved.

  8. AN ADAPTIVE AQM TO PROVIDE DELAY GUARANTEES FOR DIFFERENTIATED SERVICES

    Institute of Scientific and Technical Information of China (English)

    Yang Zongkai; Liu Wei; He Jianhua; Chou Chuntung

    2005-01-01

    RIO(RED with IN and OUT) is the primary queue management mechanism proposed for assured forwarding in the DiffServ (Differentiated Service) framework. Although RIO can generally provide bandwidth guarantees, its queuing delay is sensitive to the traffic load. This paper presents a qualitative explanation for its origin. As a solution, an Adaptive RIO for Delay (ARIO-D) is proposed to provide guaranteed delay for multimedia traffic. Simulation results show that by trading loss for delay, ARIO-D can effectively improve the robustness of RIO under different and dynamic traffic, and provide stable and differentiated performance of queuing delay without any degradation in performance of throughput.

  9. On multi-class multi-server queueing and spare parts management

    NARCIS (Netherlands)

    Harten, van Aart; Sleptchenko, Andrei

    2000-01-01

    Multi-class multi-server queuing problems are a generalization of the wellknown M/M/k situation to arrival processes with clients of N types that require exponentially distributed service with different averaged service time. Problems of this sort arise naturally in various applications, such as spa

  10. ANALYSING SURFACE MOVEMENT DELAYS IN AN AIRPORT

    Directory of Open Access Journals (Sweden)

    Volodymyr Kharchenko

    2014-07-01

    Full Text Available Queuing effect can be in the different components of ground operations. Causes of surface – movement delays are long taxi – in and taxi – out operations during departure and arrival of aircraft. Surface movement delays in an airport are analyzed

  11. parallelization, Hadoop, Google File Systems, Map Reduce, Distributed File System

    Directory of Open Access Journals (Sweden)

    Jitendra Saxena

    2012-02-01

    Full Text Available Eminence of service is a extremely significant and critical concern for maintaining optical network with respect signal degradation. Queuing theory is an vital parameter to maintain voice video and data eminence of service. The network consists of different type of eminence of service model with priority of service with special reference to delay, speed and jitter

  12. Analysis and implementation of packet preemption for Time Sensitive Networks

    DEFF Research Database (Denmark)

    Zhou, Zifan; Yan, Ying; Ruepp, Sarah Renée

    2017-01-01

    level simulation in Riverbed Modeler. The simulation is complemented by numerical analysis which provides the average queuing delay for both types of traffic (preemptable and express). Furthermore, the paper describes an approach to implement the packet preemption solution on an FPGA in VHDL, which...

  13. Schedulability Analysis and Optimization for the Synthesis of Multi-Cluster Distributed Embedded Systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    2003-01-01

    An approach to schedulability analysis for the synthesis of multi-cluster distributed embedded systems consisting of time-triggered and event-triggered clusters, interconnected via gateways, is presented. A buffer size and worst case queuing delay analysis for the gateways, responsible for routing...

  14. Minimizing the Delay at Traffic Lights

    Science.gov (United States)

    Van Hecke, Tanja

    2009-01-01

    Vehicles holding at traffic lights is a typical queuing problem. At crossings the vehicles experience delay in both directions. Longer periods with green lights in one direction are disadvantageous for the vehicles coming from the other direction. The total delay for getting through the traffic point is what counts. This article presents an…

  15. Modelling delay propagation within an airport network

    NARCIS (Netherlands)

    Pyrgiotis, N.; Malone, K.M.; Odoni, A.

    2013-01-01

    We describe an analytical queuing and network decomposition model developed to study the complex phenomenon of the propagation of delays within a large network of major airports. The Approximate Network Delays (AND) model computes the delays due to local congestion at individual airports and capture

  16. Status of the French photovoltaic fleet on the 30 September 2011; Etat des lieux du parc photovoltaique francais au 30 septembre 2011

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-01-15

    This publication first present some key data regarding photovoltaic energy production in France (connected and to be connected), and then presents the photovoltaic fleet (geographical distribution, installed power in metropolitan France, Corsica and ultramarine territories). It gives an overview of the evolution of connection request and queuing management in France and at the regional level

  17. A Strategic Approach to Optimizing the U.S. Army’s Aeromedical Evacuation System in Afghanistan

    Science.gov (United States)

    2009-07-10

    and providing various other health and preventive medicine services. Furthermore, the HSS system incorporates the maximum use of emerging technology...Priorities: The Priority Queuing Covering Location Problem.” Ministerio de Ciencia y Tecnologia . Snyder, L. (2006) Facility Location Under

  18. AMOS Phase 3 Program. Volume 1

    Science.gov (United States)

    1978-03-01

    drive sprockets did not mesh well with the chain due, primarily, to the out-of-round condition of the dome. This condition caused rough...possible with the Phase III system. Improved servo performance was achieved as a function of the rede - sign of task scheduling, queuing and interrupt

  19. Cross-training workers in dual resource constrained systems with heterogeneous processing times

    NARCIS (Netherlands)

    Bokhorst, J. A. C.; Gaalman, G. J. C.

    2009-01-01

    In this paper, we explore the effect of cross-training workers in Dual Resource Constrained (DRC) systems with machines having different mean processing times. By means of queuing and simulation analysis, we show that the detrimental effects of pooling (cross-training) previously found in single res

  20. Social influence, agent heterogeneity and the emergence of the urban informal sector

    NARCIS (Netherlands)

    Garcia-Diaz, Cesar; Moreno-Monroy, Ana I.

    2012-01-01

    We develop an agent-based computational model in which the urban informal sector acts as a buffer where rural migrants can earn some income while queuing for higher paying modern-sector jobs. In the model, the informal sector emerges as a result of rural-urban migration decisions of heterogeneous ag

  1. Surprise as a design strategy

    NARCIS (Netherlands)

    Ludden, G.D.S.; Schifferstein, H.N.J.; Hekkert, P.P.M.

    2008-01-01

    Imagine yourself queuing for the cashier’s desk in a supermarket. Naturally, you have picked the wrong line, the one that does not seem to move at all. Soon, you get tired of waiting. Now, how would you feel if the cashier suddenly started to sing? Many of us would be surprised and, regardless of

  2. Surprise as a design strategy

    NARCIS (Netherlands)

    Ludden, G.D.S.; Schifferstein, H.N.J.; Hekkert, P.P.M.

    2008-01-01

    Imagine yourself queuing for the cashier’s desk in a supermarket. Naturally, you have picked the wrong line, the one that does not seem to move at all. Soon, you get tired of waiting. Now, how would you feel if the cashier suddenly started to sing? Many of us would be surprised and, regardless of th

  3. The Good and the Bad – Bicyclists’ Experiences In Copenhagen

    DEFF Research Database (Denmark)

    Snizek, Bernhard; Skov-Petersen, Hans; Nielsen, Thomas Alexander Sick

    The Good and the Bad – Bicyclists’ Experiences In Copenhagen In order to design livable cities, a strategy of substituting motorized travel modes with non-motorized ones can be a solution to the problems of crowding/queuing and CO2 emissions. Prior to investing into bike infrastructure, knowledge...

  4. Combining hardware and simulation for datacenter scaling studies

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Pilimon, Artur; Thrane, Jakob

    2017-01-01

    and simulation to illustrate the scalability and performance of datacenter networks. We simulate a Datacenter network and interconnect it with real world traffic generation hardware. Analysis of the introduced packet conversion and virtual queueing delays shows that the conversion efficiency is at the order...... of a few microseconds, but the virtual queuing may have significant implication on the performance analysis results....

  5. Modeling, Analysis, and Design Insights for Shuttle-based Compact Storage Systems

    NARCIS (Netherlands)

    E. Tappia (Elena); D. Roy (Debjit); M.B.M. de Koster (René); M. Melacini (Marco)

    2015-01-01

    textabstractShuttle-based compact systems are new automated multi-deep unit-load storage systems with lifts that promise both low operational cost and large volume flexibility. In this paper, we develop novel queuing network models to estimate the performance of both single-tier and multi-tier shutt

  6. A Fuzzy Logic Classification of Incoming Packet for VoIP

    Directory of Open Access Journals (Sweden)

    Suardinata

    2010-08-01

    Full Text Available The Voice over Internet Protocol (VoIP technology is cheaper and does not need new infrastructure because it has available in the global computer (IP network. Unfortunately, transition from PSTN to VoIP networks have emerged new problems in voice quality. Furthermore, the transmission of voice over IP networks can generate network congestion due to weak supervision of the traffic incoming packet, queuing and scheduling. This congestion affects the Quality of Service (QoS such as delay, packet drop and packet loss. Packet delay effects will affect the other QoS such as: unstable voice packet delivery, packet jitter, packet loss and echo. Priority Queuing (PQ algorithm is a popular technique used in the VoIP network to reduce delays. But, the method can result in repetition. This recursive leads to the next queue starved. To solving problems, there are three phases namely queuing, classifying and scheduling. It will be applied to the fuzzy inference system to classify the queuing incoming packet (voice, video and text. To justify the research of the improved PQ algorithm be compared against the algorithm existing.

  7. Hypercongestion in downtown metropolis

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Small, Kenneth A.

    2013-01-01

    Engineering studies demonstrate that traffic in dense downtown areas obeys a stable functional relationship between average speed and density, including a region of ‘hypercongestion’, where flow decreases with density. This situation can be described as queuing behind a bottleneck whose capacity...

  8. Nigerian journal of technology

    African Journals Online (AJOL)

    student1

    2013-07-02

    Jul 2, 2013 ... It was also observed that the waiting time in the queue and service time at the five petrol filling stations ... engineering, computing and the design of factories, shops ... associated with the buffer queuing process at each node ...

  9. Phenomena of drag reduction on saltating sediment in shallow, supercritical flows

    Science.gov (United States)

    ABSTRACT: When a group of objects move through a fluid, it often exhibits coordinated behavior in which bodies in the wake of a leader generally experience reduced drag. Locomotion provides well known examples including the maneuvering and clustering of racing automobiles and bicyclists and queuing...

  10. "I Don't Feel Right Sized; I Feel Out-of-Work Sized." Gender, Race, Ethnicity, and the Unequal Costs of Displacement.

    Science.gov (United States)

    Spalter-Roth, Roberta; Deitch, Cynthia

    1999-01-01

    Application of queuing theory to displaced-worker data indicates that White men head the queue in reemployment after displacement. White women experience gender discrimination, Black men are racially disadvantaged and do not benefit from gender, Black women are doubly disadvantaged, and Hispanic men benefit from gender. (SK)

  11. 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

  12. Modelling delay propagation within an airport network

    NARCIS (Netherlands)

    Pyrgiotis, N.; Malone, K.M.; Odoni, A.

    2013-01-01

    We describe an analytical queuing and network decomposition model developed to study the complex phenomenon of the propagation of delays within a large network of major airports. The Approximate Network Delays (AND) model computes the delays due to local congestion at individual airports and

  13. Teaching Mathematical Modelling: Demonstrating Enrichment and Elaboration

    Science.gov (United States)

    Warwick, Jon

    2015-01-01

    This paper uses a series of models to illustrate one of the fundamental processes of model building--that of enrichment and elaboration. The paper describes how a problem context is given which allows a series of models to be developed from a simple initial model using a queuing theory framework. The process encourages students to think about the…

  14. 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 o

  15. Large deviations for Gaussian queues modelling communication networks

    CERN Document Server

    Mandjes, Michel

    2007-01-01

    Michel Mandjes, Centre for Mathematics and Computer Science (CWI) Amsterdam, The Netherlands, and Professor, Faculty of Engineering, University of Twente. At CWI Mandjes is a senior researcher and Director of the Advanced Communications Network group.  He has published for 60 papers on queuing theory, networks, scheduling, and pricing of networks.

  16. A novel round-robin based multicast scheduling algorithm for 100 Gigabit Ethernet switches

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2010-01-01

    This paper proposes a round-robin based multicast scheduling algorithm for high-speed input-queued switches. Fan-out information of each head-of-line cell is examined by the packet scheduler to form a matrix called Traffic Matrix. A subscheduler for each column executes the round-robin scheduling...

  17. Packet Delay Variation Analysis of the CQ Switch

    OpenAIRE

    I. Radusinović; I. Maljević; M. Radonjić

    2012-01-01

    Packet delay variation analysis for a 32x32 crosspoint queued switch under uniform and IBP arrival traffic is presented in this paper. Different buffer sizes and several scheduling algorithms are observed: longest queue first, round robin, exhaustive round robin and frame based round robin matching. Results show that the least packet delay variation, among observed algorithms, causes round robin algorithm.

  18. Packet Delay Variation Analysis of the CQ Switch

    Directory of Open Access Journals (Sweden)

    I. Radusinović

    2012-06-01

    Full Text Available Packet delay variation analysis for a 32x32 crosspoint queued switch under uniform and IBP arrival traffic is presented in this paper. Different buffer sizes and several scheduling algorithms are observed: longest queue first, round robin, exhaustive round robin and frame based round robin matching. Results show that the least packet delay variation, among observed algorithms, causes round robin algorithm.

  19. Statistical Analysis of Random Simulations : Bootstrap Tutorial

    NARCIS (Netherlands)

    Deflandre, D.; Kleijnen, J.P.C.

    2002-01-01

    The bootstrap is a simple but versatile technique for the statistical analysis of random simulations.This tutorial explains the basics of that technique, and applies it to the well-known M/M/1 queuing simulation.In that numerical example, different responses are studied.For some responses, bootstrap

  20. Congestion Control for ATM Networks Based on Diagonal Recurrent Neural Networks

    Institute of Scientific and Technical Information of China (English)

    HuangYunxian; YanWei

    1997-01-01

    An adaptive control model and its algorithms based on simple diagonal recurrent neural networks are presented for the dynamic congestion control in broadband ATM networks.Two simple dynamic queuing models of real networks are used to test the performance of the suggested control scheme.

  1. Bayesian Inference and Prediction in an M/G/1 with Optional Second Service

    NARCIS (Netherlands)

    Mohammadi, A.; Salehi-Rad, M. R.

    2012-01-01

    In this article, we exploit the Bayesian inference and prediction for an M/G/1 queuing model with optional second re-service. In this model, a service unit attends customers arriving following a Poisson process and demanding service according to a general distribution and some of customers need to r

  2. High Performance Parallel Java with JavaParty

    Science.gov (United States)

    2008-06-01

    42 b. Queuing and Scheduling Configuration................................43 4. RayTracer Revisited...49 1. RayTracer Execution Times (From Chapter IV) ...........................49 2. RayTracer Execution...addresses for the internal cluster along with the external network information are shown in the figure.............25 Figure 7. RayTracer Benchmark

  3. Models for Planning. Analysis of Literature and Selected Bibliography. Analysis and Bibliography Series, No. 5.

    Science.gov (United States)

    ERIC Clearinghouse on Educational Management, Eugene, OR.

    This review analyzes current research trends in the application of planning models to broad educational systems. Planning models reviewed include systems approach models, simulation models, operational gaming, linear programing, Markov chain analysis, dynamic programing, and queuing techniques. A 77-item bibliography of recent literature is…

  4. A Multi-Step Simulation Approach Toward Secure Fault Tolerant System Evaluation

    Science.gov (United States)

    2010-01-01

    its current state of development. When the system architecture is not established, researchers generally use CTMC (Continuous time Markov chains ...stochastic va bandwidth, etc.) that are statistically derived experimentations. It can also be defined analysis, like the use of queuing theory in case The

  5. About Nested Circuits Markov in one Parametric Queueing Model

    Directory of Open Access Journals (Sweden)

    Rafik A. Simonyan

    2013-01-01

    Full Text Available In operation the single-channel queuing system with several Poisson entering flows and with Kleynrok's parametric discipline is considered. The Markov circuit which is received on a basis a vector of processes of the maximum priorities of flows of calls is completely studied

  6. Inhomogeneous CTMC Model of a Call Center with Balking and Abandonment

    OpenAIRE

    2015-01-01

    This paper considers a nonstationary multiserver queuing model with abandonment and balking for inbound call centers. We present a continuous time Markov chain (CTMC) model which captures the important characteristics of an inbound call center and obtain a numerical solution for its transient state probabilities using uniformization method with steady-state detection. Keywords: call center, transient, Markov processes, numerical methods, uniformization, abandonment, balking

  7. WEEKLY WATCH

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    OPINION Emergency Training Can Avert Tragedy Three people died and 31 others were injured,seven severely, in a stampede triggered by sales promotion in a Canefour outlet in southwest China’s Chongqing Municipality on November 11. People began queuing at the entrance around 4 a.m.that day,

  8. Reconfigurable layout problem

    NARCIS (Netherlands)

    Meng, G.; Heragu, S.S.; Zijm, H.

    2004-01-01

    This paper addresses the reconfigurable layout problem, which differs from traditional, robust and dynamic layout problems mainly in two aspects: first, it assumes that production data are available only for the current and upcoming production period. Second, it considers queuing performance measure

  9. THE APPLICATION OF ECONOMIC AND MATHEMATICAL METHODS FOR OPTIMIZATION OF ACTIVITIES OF ADVERTISING AGENCY

    Directory of Open Access Journals (Sweden)

    Andrei A. Romanov

    2016-01-01

    Full Text Available The accumulated experience in solving practical problems in the organization of advertising activity allows allocating four classes of problems focused on ap-plication of economic and mathematical methods - resource allocation, queuing problem, network planning and combina-torial problems

  10. Probabilistic modeling of nodal electric vehicle load due to fast charging stations

    DEFF Research Database (Denmark)

    Tang, Difei; Wang, Peng; Wu, Qiuwei

    2016-01-01

    station into consideration. Fuzzy logic inference system is applied to simulate the charging decision of EV drivers at fast charging station. Due to increasing EV loads in power system, the potential traffic congestion in fast charging stations is modeled and evaluated by queuing theory with spatial...

  11. Based on Regular Expression Matching of Evaluation of the Task Performance in WSN: A Queue Theory Approach

    Directory of Open Access Journals (Sweden)

    Jie Wang

    2014-01-01

    Full Text Available Due to the limited resources of wireless sensor network, low efficiency of real-time communication scheduling, poor safety defects, and so forth, a queuing performance evaluation approach based on regular expression match is proposed, which is a method that consists of matching preprocessing phase, validation phase, and queuing model of performance evaluation phase. Firstly, the subset of related sequence is generated in preprocessing phase, guiding the validation phase distributed matching. Secondly, in the validation phase, the subset of features clustering, the compressed matching table is more convenient for distributed parallel matching. Finally, based on the queuing model, the sensor networks of task scheduling dynamic performance are evaluated. Experiments show that our approach ensures accurate matching and computational efficiency of more than 70%; it not only effectively detects data packets and access control, but also uses queuing method to determine the parameters of task scheduling in wireless sensor networks. The method for medium scale or large scale distributed wireless node has a good applicability.

  12. Simulating Mission Command for Planning and Analysis

    Science.gov (United States)

    2015-06-01

    parameters do not change. A good example of parameters is the number of servers in a queuing system. 4. Next Event Algorithm In DES systems, next...I Finish 98 THIS PAGE INTENTIONALLY LEFT BLANK 99 LIST OF REFERENCES Ben-Shalom, U., & Shamir, E. (2011). Mission command between theory and

  13. Letter to the Editor: Electric Vehicle Demand Model for Load Flow Studies

    DEFF Research Database (Denmark)

    Garcia-Valle, Rodrigo; Vlachogiannis, Ioannis (John)

    2009-01-01

    This paper introduces specific and simple model for electric vehicles suitable for load flow studies. The electric vehicles demand system is modelled as PQ bus with stochastic characteristics based on the concept of queuing theory. All appropriate variables of stochastic PQ buses are given...

  14. Finding External Indicators of Load on a Web Server via Analysis of Black-Box Performance Measurements

    Science.gov (United States)

    Chiarini, Marc A.

    2010-01-01

    Traditional methods for system performance analysis have long relied on a mix of queuing theory, detailed system knowledge, intuition, and trial-and-error. These approaches often require construction of incomplete gray-box models that can be costly to build and difficult to scale or generalize. In this thesis, we present a black-box analysis…

  15. Teaching Mathematical Modelling: Demonstrating Enrichment and Elaboration

    Science.gov (United States)

    Warwick, Jon

    2015-01-01

    This paper uses a series of models to illustrate one of the fundamental processes of model building--that of enrichment and elaboration. The paper describes how a problem context is given which allows a series of models to be developed from a simple initial model using a queuing theory framework. The process encourages students to think about the…

  16. On the reliability of a renewable multiple cold standby system

    Directory of Open Access Journals (Sweden)

    Vanderperre E. J.

    2005-01-01

    Full Text Available We present a general reliability analysis of a renewable multiple cold standby system attended by a single repairman. Our analysis is based on a refined methodology of queuing theory. The particular case of deterministic failures provides an explicit exact result for the survival function of the duplex system.

  17. The Optimal Management of Informational Servicing Logistic Systems

    Directory of Open Access Journals (Sweden)

    Safwan Al SALAIMEH

    2007-01-01

    Full Text Available This paper reviews optimization problems of informational servicing logistic systems (ISLS management in problems class, which can be solved by the queuing system (QS theory. Examples of mathematics models building and effective algorithm development for quasi-optimal management of informational servicing logistic systems are presented.

  18. Based on regular expression matching of evaluation of the task performance in WSN: a queue theory approach.

    Science.gov (United States)

    Wang, Jie; Cui, Kai; Zhou, Kuanjiu; Yu, Yanshuo

    2014-01-01

    Due to the limited resources of wireless sensor network, low efficiency of real-time communication scheduling, poor safety defects, and so forth, a queuing performance evaluation approach based on regular expression match is proposed, which is a method that consists of matching preprocessing phase, validation phase, and queuing model of performance evaluation phase. Firstly, the subset of related sequence is generated in preprocessing phase, guiding the validation phase distributed matching. Secondly, in the validation phase, the subset of features clustering, the compressed matching table is more convenient for distributed parallel matching. Finally, based on the queuing model, the sensor networks of task scheduling dynamic performance are evaluated. Experiments show that our approach ensures accurate matching and computational efficiency of more than 70%; it not only effectively detects data packets and access control, but also uses queuing method to determine the parameters of task scheduling in wireless sensor networks. The method for medium scale or large scale distributed wireless node has a good applicability.

  19. Cache-based memory copy hardware accelerator for multicore systems

    NARCIS (Netherlands)

    Duarte, F.; Wong, S.

    2010-01-01

    In this paper, we present a new architecture of the cache-based memory copy hardware accelerator in a multicore system supporting message passing. The accelerator is able to accelerate memory data movements, in particular memory copies. We perform an analytical analysis based on open-queuing theory

  20. Reconfigurable layout problem

    NARCIS (Netherlands)

    Meng, G.; Heragu, S.S.; Heragu, S.S.; Zijm, Willem H.M.

    2004-01-01

    This paper addresses the reconfigurable layout problem, which differs from traditional, robust and dynamic layout problems mainly in two aspects: first, it assumes that production data are available only for the current and upcoming production period. Second, it considers queuing performance measure

  1. Capacitated two-echelon inventory models for repairable item systems

    NARCIS (Netherlands)

    Avsar, Z.M.; Zijm, Willem H.M.; Gershwin, S.B.; Dallery, Y.; Papadopoulos, C.; Smith, J.M.

    2002-01-01

    In this paper, we consider two-echelon maintenance systems with repair facilities both at a number of local service centers (called bases) and at a central location. Each repair facility may be considered to be a job shop and is modeled as a (limited capacity) open queuing network, while any

  2. End-to-end Configuration of Wireless Realtime Communication over Heterogeneous Protocols

    DEFF Research Database (Denmark)

    Malinowsky, B.; Grønbæk, Jesper; Schwefel, Hans-Peter

    2015-01-01

    This paper describes a wireless real-time communication system design using two Time Division Multiple Access (TDMA) protocols. Messages are subject to prioritization and queuing. For this interoperation scenario, we show a method for end-to-end configuration of protocols and queue sizes. Such co...

  3. Occupational Feminization and Pay: Assessing Causal Dynamics Using 1950-2000 U.S. Census Data

    Science.gov (United States)

    Levanon, Asaf; England, Paula; Allison, Paul

    2009-01-01

    Occupations with a greater share of females pay less than those with a lower share, controlling for education and skill. This association is explained by two dominant views: devaluation and queuing. The former views the pay offered in an occupation to affect its female proportion, due to employers' preference for men--a gendered labor queue. The…

  4. Cross-layer resource allocation for QoS guarantee with finite queue constraint in multirate OFDMA wireless networks

    Institute of Scientific and Technical Information of China (English)

    XU Hai-bo; TIAN Hui; FENG Yuan

    2008-01-01

    Efficient radio resource allocation is essential to provide quality of service (QoS) for wireless networks. In this article, a cross-layer resource allocation scheme is presented with the objective of maximizing system throughput, while providing guaranteed QoS for users. With the assumption of a finite queue for arrival packets, the proposed scheme dynamically allocates radio resources based on user's channel characteristic and QoS metrics derived from a queuing model, which considers a packet arrival process modeled by discrete Markov modulated Poisson process (dMMPP), and a multirate transmission scheme achieved through adaptive modulation. The cross-layer resource allocation scheme operates over two steps. Specifically, the amount of bandwidth allocated to each user is first derived from a queuing analytical model, and then the algorithm finds the best subcarrier assignment for users. Simulation results show that the proposed scheme maximizes the system throughput while guaranteeing QoS for users.

  5. Improving Internet Quality of Service through Active Queue Management in Routers

    Directory of Open Access Journals (Sweden)

    Gamal Attiya

    2012-01-01

    Full Text Available The traffic characteristics of real-time and non real-time applications require a certain Quality of Service (QoS from the Internet in terms of bandwidth, delay, packet loss, fairness and jitter. However, most of the current Active Queue Management (AQM algorithms at the internet routers do not guarantee QoS for real time traffics such as video and audio. This is because; most of the algorithms handle different packets of different traffics by the same strategy. In this paper, we propose a new AQM strategy to guarantee QoS for real time traffics. The proposed strategy uses three queues at the internet routers, each of which handles a single class of traffic. Where, the arriving packets are queued according to their class type. Additionally, the queued packets are scheduled according to a predefined weight. The proposed algorithm is evaluated and compared with the most recent algorithms by using the Network simulator NS-2.

  6. Effective usage of shortest paths promotes transportation efficiency on scale-free networks

    Science.gov (United States)

    Du, Wen-Bo; Wu, Zhi-Xi; Cai, Kai-Quan

    2013-09-01

    With rapid economic and social development, the problem of traffic congestion is getting more and more serious. Accordingly, network traffic models have attracted extensive attention. In this paper, we introduce a shortest-remaining-path-first queuing strategy into a network traffic model on Barabási-Albert scale-free networks under efficient routing protocol, where one packet’s delivery priority is related to its current distance to the destination. Compared with the traditional first-in-first-out queuing strategy, although the network capacity has no evident changes, some other indexes reflecting transportation efficiency are significantly improved in the congestion state. Extensive simulation results and discussions are carried out to explain the phenomena. Our work may be helpful for the designing of optimal networked-traffic systems.

  7. Packet transfer delay analysis of the RPR rings in the store-and-forward architecture

    Science.gov (United States)

    Yang, Yi; Cao, Mingcui; Huang, Ping

    2005-02-01

    RRP has two means to transmit data: store-and-forward and cut-through. In this paper, the high and low priority packet transfer delay of the N nodes Resilient Packet Rings (RPR) in store-and-forward architecture is analyzed based on the queuing theory. According to queuing theory, we set up the nodes model and analyzed the factors that influenced the packet transfer delay in a constrained condition. By calculation and simulation, the result indicates that both high priority and low priority packets" delay increase with the node number N of the RPR rings. The high priority traffic has less packet delay than the low priority traffic at the same node number N. The increase of the low priority transfer delay is much larger than the high priority traffic with the increase of the node number.

  8. The classification and analysis of dynamic networks

    Institute of Scientific and Technical Information of China (English)

    Guo Jin-Li

    2007-01-01

    In this paper we, firstly, classify the complex networks in which the nodes are of the lifetime distribution. Secondly, in order to study complex networks in terms of queuing system and homogeneous Markov chain, we establish the relation between the complex networks and queuing system, providing a new way of studying complex networks. Thirdly, we prove that there exist stationary degree distributions of M-G-P network, and obtain the analytic expression of the distribution by means of Markov chain theory. We also obtain the average path length and clustering coefficient of the network. The results show that M-G-P network is not only scale-free but also of a small-world feature in proper conditions.

  9. Performance analysis of fault-tolerant systems in parallel execution of conversations

    Science.gov (United States)

    Kim, K. H.; Heu, Shin; Yang, Seung M.

    1989-01-01

    The execution overhead inherent in the conversation scheme, which is a scheme for realizing fault-tolerant cooperating processes free of the domino effect, is analyzed. Multiprocessor/multicomputer systems capable of parallel execution of conversation components are considered and a queuing network model of such systems is adopted. Based on the queuing model, various performance indicators, including system throughput, average number of processors idling inside a conversation due to the synchronization required, and average time spent in the conversation, have been evaluated numerically for several application environments. The numeric results are discussed and several essential performance characteristics of the conversation scheme are derived. For example, when the number of participant processes is not large, say less than six, the system performance is highly affected by the synchronization required on the processes in a conversation, and not so much by the probability of acceptance-test failure.

  10. Data Processing Model of Coalmine Gas Early-Warning System

    Institute of Scientific and Technical Information of China (English)

    QIAN Jian-sheng; YIN Hong-sheng; LIU Xiu-rong; HUA Gang; XU Yong-gang

    2007-01-01

    The data processing mode is vital to the performance of an entire coalmine gas early-warning system, especially in real-time performance. Our objective was to present the structural features of coalmine gas data, so that the data could be processed at different priority levels in C language. Two different data processing models, one with priority and the other without priority, were built based on queuing theory. Their theoretical formulas were determined via a M/M/1 model in order to calculate average occupation time of each measuring point in an early-warning program. We validated the model with the gas early-warning system of the Huaibei Coalmine Group Corp. The results indicate that the average occupation time for gas data processing by using the queuing system model with priority is nearly 1/30 of that of the model without priority..

  11. On the impact of TCP and per-flow scheduling on Internet performance (extended version)

    CERN Document Server

    Carofiglio, Giovanna

    2009-01-01

    Internet performance is tightly related to the properties of TCP and UDP protocols, jointly responsible for the delivery of the great majority of Internet traffic. It is well understood how these protocols behave under FIFO queuing and what the network congestion effects. However, no comprehensive analysis is available when flow-aware mechanisms such as per-flow scheduling and dropping policies are deployed. Previous simulation and experimental results leave a number of unanswered questions. In the paper, we tackle this issue by modeling via a set of fluid non-linear ODEs the instantaneous throughput and the buffer occupancy of N long-lived TCP sources under three per-flow scheduling disciplines (Fair Queuing, Longest Queue First, Shortest Queue First) and with longest queue drop buffer management. We study the system evolution and analytically characterize the stationary regime: closed-form expressions are derived for the stationary throughput/sending rate and buffer occupancy which give thorough understandi...

  12. Transient and stationary characteristics of a packet buffer modelled as an MAP/SM/1/b system

    Directory of Open Access Journals (Sweden)

    Rusek Krzysztof

    2014-06-01

    Full Text Available A packet buffer limited to a fixed number of packets (regardless of their lengths is considered. The buffer is described as a finite FIFO queuing system fed by a Markovian Arrival Process (MAP with service times forming a Semi-Markov (SM process (MAP /SM /1/b in Kendall’s notation. Such assumptions allow us to obtain new analytical results for the queuing characteristics of the buffer. In the paper, the following are considered: the time to fill the buffer, the local loss intensity, the loss ratio, and the total number of losses in a given time interval. Predictions of the proposed model are much closer to the trace-driven simulation results compared with the prediction of the MAP /G/1/b model.

  13. Reliable routing algorithm in marine ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    LIN Wei; YANG Yong-Tian

    2004-01-01

    A routing algorithm called DNH for increasing efficiency of mobile ad hoc network is presented, which is based on a new criterion called TSS ( Temporarily Steady State) , combining with wireless transmission theory that makes networks topology correspondingly stabilization. Also the DNH algorithm has the characteristics of giving up queuing in a node, but selecting another idle node instead of the node for forwarding data packets if the node has a full throughput. Simulation evaluation shows that selecting another node is better than queuing in a full throughout node if some conditions are satisfied, especially during a sea battle, every warship in ad hoc network wants to contest time and increase propagation reliability. The DNH algorithm can help decrease routing time, and raise efficiency of marine ad hoc networks.

  14. Assessment of Active Queue Management algorithms by using NS2 simulator

    Directory of Open Access Journals (Sweden)

    Kamal Preet Kaur

    2014-03-01

    Full Text Available Network security has become very important and foremost issue for the personal computer users, organizations, business and military. With the advent of internet, security has become the major concern. The main objective of this research is to simulate and analyze the effect of queuing algorithms RED and DROPTAIL with CPR on the TCP targeted LDDoS attack flows. LDDoS attack is more vulnerable to the network traffic than the classic DDoS attacks as they are difficult to identify. We use network simulator ns-2 to implement the network and investigate the behaviors of queuing algorithms in the network. The performance metrics of the comparison are average delay and packet drop. CPR based approach is used to detect and filter attacks. The test-bed experiments are conducted to analyze the performance of this approach which is compared to the existing DFT approach.

  15. Parameter Estimation for Generalized Brownian Motion with Autoregressive Increments

    CERN Document Server

    Fendick, Kerry

    2011-01-01

    This paper develops methods for estimating parameters for a generalization of Brownian motion with autoregressive increments called a Brownian ray with drift. We show that a superposition of Brownian rays with drift depends on three types of parameters - a drift coefficient, autoregressive coefficients, and volatility matrix elements, and we introduce methods for estimating each of these types of parameters using multidimensional times series data. We also cover parameter estimation in the contexts of two applications of Brownian rays in the financial sphere: queuing analysis and option valuation. For queuing analysis, we show how samples of queue lengths can be used to estimate the conditional expectation functions for the length of the queue and for increments in its net input and lost potential output. For option valuation, we show how the Black-Scholes-Merton formula depends on the price of the security on which the option is written through estimates not only of its volatility, but also of a coefficient ...

  16. 高考阅读理解解析一则(英文)

    Institute of Scientific and Technical Information of China (English)

    黄华斌

    2005-01-01

    In1837,the historian Carlyle m ade the firstrecorded use of the word“queue”(排队).H e spoke ofthe French and their“habit of standing in a queue”.Forty years later Paris was the best place to wait inline.H owever,queuing becam e popular in Britain too.The Second W orld W ar was the golden age of queuing,and people joined any line in the hope that it was aqueue for som ething to buy.This was the source ofm any Second W orld W ar jokes:Shopkeeper to custom er:Excuse m e,m iss,are youpregnant(怀孕)?Custom er:W ell,...

  17. A novel crowd flow model based on linear fractional stable motion

    Science.gov (United States)

    Wei, Juan; Zhang, Hong; Wu, Zhenya; He, Junlin; Guo, Yangyong

    2016-03-01

    For the evacuation dynamics in indoor space, a novel crowd flow model is put forward based on Linear Fractional Stable Motion. Based on position attraction and queuing time, the calculation formula of movement probability is defined and the queuing time is depicted according to linear fractal stable movement. At last, an experiment and simulation platform can be used for performance analysis, studying deeply the relation among system evacuation time, crowd density and exit flow rate. It is concluded that the evacuation time and the exit flow rate have positive correlations with the crowd density, and when the exit width reaches to the threshold value, it will not effectively decrease the evacuation time by further increasing the exit width.

  18. An Efficient Multitask Scheduling Model for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Hongsheng Yin

    2014-01-01

    Full Text Available The sensor nodes of multitask wireless network are constrained in performance-driven computation. Theoretical studies on the data processing model of wireless sensor nodes suggest satisfying the requirements of high qualities of service (QoS of multiple application networks, thus improving the efficiency of network. In this paper, we present the priority based data processing model for multitask sensor nodes in the architecture of multitask wireless sensor network. The proposed model is deduced with the M/M/1 queuing model based on the queuing theory where the average delay of data packets passing by sensor nodes is estimated. The model is validated with the real data from the Huoerxinhe Coal Mine. By applying the proposed priority based data processing model in the multitask wireless sensor network, the average delay of data packets in a sensor nodes is reduced nearly to 50%. The simulation results show that the proposed model can improve the throughput of network efficiently.

  19. 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.

  20. TWO PARALLEL RUNWAYS CAPACITY ACCORDING TO DIFFERENT ORGANIZATION OF AIRPLANES FLIGHTS AT THE AERODROME

    Directory of Open Access Journals (Sweden)

    В. Золотоперий

    2011-02-01

    Full Text Available The capacity of the runways of  the aerodrome is one of the  most important performance  characteristics of the airport. In theory, the system of runways can be seen as queuing system with the expectation that is used for  servicing of different kinds of airplane's take off and landing  operations. By using the apparatus of the queuing theory derived mathematical relations for  determining the rated capacity of the system  of two parallel independent non-specialized, two  parallel independent specialized and two parallel dependent specialized runways. The obtained mathematical relations allow us to determine the most appropriate organization of airplanes flights at the aerodrome

  1. Predictive analysis of shaft station radon concentrations in underground uranium mine: A case study.

    Science.gov (United States)

    Zhao, Guoyan; Hong, Changshou; Li, Xiangyang; Lin, Chunping; Hu, Penghua

    2016-07-01

    This paper presented a method for predicting shaft station radon concentrations in a uranium mine of China through theoretical analysis, mathematical derivation and Monte-Carlo simulation. Based upon the queuing model for tramcars, the average waiting time of tramcars and average number of waiting tramcars were determined, which were further used in developing the predictive model for calculating shaft station radon concentrations. The results exhibit that the extent of variation of shaft station radon concentration in the case study mine is not significantly affected by the queuing process of tramcars, and is always within the allowable limit of 200 Bq m(-3). Thus, the empirical limit of 100,000 T annual ore-hoisting yields has no value in ensuring radiation safety for this mine. Moreover, the developed model has been validated and proved useful in assessing shaft station radon levels for any uranium mine with similar situations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. 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...

  3. An agent-based model for queue formation of powered two-wheelers in heterogeneous traffic

    Science.gov (United States)

    Lee, Tzu-Chang; Wong, K. I.

    2016-11-01

    This paper presents an agent-based model (ABM) for simulating the queue formation of powered two-wheelers (PTWs) in heterogeneous traffic at a signalized intersection. The main novelty is that the proposed interaction rule describing the position choice behavior of PTWs when queuing in heterogeneous traffic can capture the stochastic nature of the decision making process. The interaction rule is formulated as a multinomial logit model, which is calibrated by using a microscopic traffic trajectory dataset obtained from video footage. The ABM is validated against the survey data for the vehicular trajectory patterns, queuing patterns, queue lengths, and discharge rates. The results demonstrate that the proposed model is capable of replicating the observed queue formation process for heterogeneous traffic.

  4. Ribosome collisions and Translation efficiency: Optimization by codon usage and mRNA destabilization

    DEFF Research Database (Denmark)

    Mitarai, Namiko; Sneppen, Kim; Pedersen, Steen

    2008-01-01

    Individual mRNAs are translated by multiple ribosomes that initiate translation with an interval of a few seconds. The ribosome speed is codon dependent, and ribosome queuing has been suggested to explain specific data for translation of some mRNAs in vivo. By modeling the stochastic translation...... process as a traffic problem, we here analyze conditions and consequences of collisions and queuing. The model allowed us to determine the on-rate (0.8 to 1.1 initiations/s) and the time (1 s) the preceding ribosome occludes initiation for Escherichia coli lacZ mRNA in vivo. We find that ribosome...... collisions and queues are inevitable consequences of a stochastic translation mechanism that reduce the translation efficiency substantially on natural mRNAs. The cells minimize collisions by having its mRNAs being unstable and by a highly selected codon usage in the start of the mRNA. The cost of m...

  5. A Model for the Handover Traffic and Channel Occupancy Time in LEO Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    WangJingyu; YaoYongyang

    1995-01-01

    This paper presents a method to determine the parameters of the traffic model for the LEO satellite networks-the handover traffic and the mean channel occupancy time.The main idea is that the handover traffic is mainly due to the movement of the satellites and the velocity of the mobile terminals and earth rotation is ignored.The performance level can be calculated accord-ing to different handover queuing model.

  6. Analyzing and Comparing Biomass Feedstock Supply Systems in China: Corn Stover and Sweet Sorghum Case Studies

    OpenAIRE

    Lantian Ren; Kara Cafferty; Mohammad Roni; Jacob Jacobson; Guanghui Xie; Leslie Ovard; Christopher Wright

    2015-01-01

    This paper analyzes the rural Chinese biomass supply system and models supply chain operations according to U.S. concepts of logistical unit operations: harvest and collection, storage, transportation, preprocessing, and handling and queuing. In this paper, we quantify the logistics cost of corn stover and sweet sorghum in China under different scenarios. We analyze three scenarios of corn stover logistics from northeast China and three scenarios of sweet sorghum stalks logistics from Inner M...

  7. 基于M/G/C排队模型的地铁人行通道宽度设置%Determined Method of Subway Footway Width Based on M/G/C Gueuing Model

    Institute of Scientific and Technical Information of China (English)

    金瑞俊; 陈京荣; 尉陇亮; 崔笑川

    2013-01-01

    通过分析地铁人行通道内的客流特性,依据行人流将整个通道划分为相反方向的2个独立通道,每个通道构成一个排队系统.分析排队系统的参数特性,建立M/G/C排队优化模型,得出地铁通道宽度的设置方法.利用专业的Simio仿真软件,建立地铁通道内的客流仿真模型,并对所建立的排队优化模型进行验证,使得对满足最大客流需求的地铁通道的设置具有理论依据和实际操作性.%The footway is divided into 2 channels whose directions are opposite based on passenger flow by analyzing the characteristics of passenger flow in subway, and each channel was described as a queuing system. The M/G/C queuing optimization model was built based on the analysis of parameter characteristics of queuing system, and an approach for determining subway footway width was obtained. A simulation model was built by using professional Simio simulation software, which was proposed to testify the queuing optimization model, and it makes the approach for determining subway footway width which meets the maximum value of passenger flow with theoretical basis and practical operation.

  8. Mobile Location Sharing: An Energy Consumption Study

    OpenAIRE

    Vergara Alonso, Ekhiotz Jon; Prihodko, Mihails; Nadjm-Tehrani, Simin

    2013-01-01

    The use of a mobile device's battery for frequent transmissions of position data in a location sharing application can be more expensive than the location retrieval itself. This is in part due to energy-agnostic application development and in part dependent on choice of protocols. This paper studies the lightweight Message Queuing Telemetry Transport protocol (MQTT) as an application layer protocol on top of the third generation cellular communication. The energy efficiency and amount of data...

  9. Federal Plan for Cyber Security and Information Assurance Research and Development

    Science.gov (United States)

    2006-04-01

    attribution 1.1 Authentication, Authorization, and Trust Management Definition Authentication is the process of verifying the identity or authority of a...November 2005, for elaboration). Functional Cyber Security 33 1.2 Access Control and Privilege Management Definition Access control and privilege...management and real-time queuing theory. 5.11 Integrated, Enterprise-Wide Security Monitoring and Management Definition An enterprise consists of one or

  10. Use your phone to build a simple laparoscopic trainer

    Directory of Open Access Journals (Sweden)

    B H van Duren

    2014-01-01

    Full Text Available Simulation is becoming increasingly integral to surgical training with progressive restrictions on working hours. This paper describes a unique, cable free, laparoscopic trainer that can be constructed using items readily available to the average surgical trainee. The trainer described is not a substitute for surgical practice but, nonetheless, a useful tool in developing skills such as hand-eye co-ordination, triangulation and depth queuing.

  11. Analysis and Modeling of Pedestrian Walking Behaviors Involving Individuals with Disabilities

    OpenAIRE

    Sharifi, Mohammad Sadra

    2016-01-01

    The objective of this dissertation was to study walking behaviors of pedestrian groups involving individuals with disabilities. To this end, large scale controlled walking experiments were conducted at Utah State University (USU) to examine walking behaviors in various walking facility types, such as passageway, right angle, oblique angle, queuing area, bottleneck, and stairs. Walking experiments were conducted over four days involving participants with and without disabilities. Automated vid...

  12. Renewal processes

    CERN Document Server

    Mitov, Kosto V

    2014-01-01

    This monograph serves as an introductory text to classical renewal theory and some of its applications for graduate students and researchers in mathematics and probability theory. Renewal processes play an important part in modeling many phenomena in insurance, finance, queuing systems, inventory control and other areas. In this book, an overview of univariate renewal theory is given and renewal processes in the non-lattice and lattice case are discussed. A pre-requisite is a basic knowledge of probability theory.

  13. Waiting Lines and Customer Satisfaction

    OpenAIRE

    Sridhar, M. S.

    2001-01-01

    The paper points out certain quantitative methods largely ignored by library service providers, highlights the importance of customer participation in service delivery process, examines the concepts service quality and customer satisfaction, emphasizes the need for appropriately handling waiting lines in service organisations, presents briefly the theory of waiting lines (queuing theory), psychology of customers in waiting lines with illustrations from library situations, discusses ways and m...

  14. The Optimizing QoS Miss Rate Scheme for the Data Centers

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, we discuss quality of service requirements and impacts of different workloads of each service class on the resource proportion allocation scheme, and formulize the problem of minimizing the quality of service miss rate of service requests by using the queuing theory. The optimally allocating resource proportion scheme is obtained by the Lagrangian optimization approach. Our simulation results show that our scheme is efficient.

  15. Car Delay Model near Bus Stops with Mixed Traffic Flow

    OpenAIRE

    Yang Xiaobao; Huan Mei; Gao Ziyou

    2013-01-01

    This paper proposes a model for estimating car delays at bus stops under mixed traffic using probability theory and queuing theory. The roadway is divided to serve motorized and nonmotorized traffic streams. Bus stops are located on the nonmotorized lanes. When buses dwell at the stop, they block the bicycles. Thus, two conflict points between car stream and other traffic stream are identified. The first conflict point occurs as bicycles merge to the motorized lane to avoid waiting behind the...

  16. Delivery Commitments in Stochastic Service Networks: Case of Automobile Service

    OpenAIRE

    Sandeep Dulluri; Ganesh Muthusamy

    2013-01-01

    Service firms have become highly competitive in terms of providing the delivery. The delivery quality in terms of delivery commitments. Delivery commitments impact the customer in deciding for the service. Computing the delivery commitments in stochastic service systems is a real challenge. Delivery commitment forms a key parameter in formulating the service level agreements in B2B markets. In our current work we propose a queuing theoretic approach for computing the delivery commitments. The...

  17. Modeling and simulation for a new virtual-clock-based collision resolution algorithm

    Institute of Scientific and Technical Information of China (English)

    Yin rupo; Cai yunze; He xing; Zhang weidong; Xu xiaoming

    2006-01-01

    Virtual time Ethernet is a multiple access protocol proposed to provide FCFS transmission service over the predominant Ethernet bus. It incorporates a novel message-rescheduling algorithm based on the virtual clock mechanism. By manipulating virtual clocks back up over a common virtual time axis and performing timely collision resolution, the algorithm guarantees the system's queuing strictness. The protocol is particularly modeled as a finite state machine and implemented using OPNET tools. Simulation studies prove its correctness and effectiveness.

  18. Delivery Commitments in Stochastic Service Networks: Case of Automobile Service

    OpenAIRE

    Sandeep Dulluri; Ganesh Muthusamy

    2013-01-01

    Service firms have become highly competitive in terms of providing the delivery. The delivery quality in terms of delivery commitments. Delivery commitments impact the customer in deciding for the service. Computing the delivery commitments in stochastic service systems is a real challenge. Delivery commitment forms a key parameter in formulating the service level agreements in B2B markets. In our current work we propose a queuing theoretic approach for computing the delivery commitments. The...

  19. "The tail wags the dog": A study of anomaly detection in commercial application performance

    OpenAIRE

    Gow, Richard; Venugopal, Srikumar; Ray, Pradeep

    2013-01-01

    The IT industry needs systems management models that leverage available application information to detect quality of service, scalability and health of service. Ideally this technique would be common for varying application types with different n-tier architectures under normal production conditions of varying load, user session traffic, transaction type, transaction mix, and hosting environment. This paper shows that a whole of service measurement paradigm utilizing a black box M/M/1 queuing...

  20. The Network effects of Railway Investments

    DEFF Research Database (Denmark)

    Hansen, Sten; Landex, Alex; Kaas, Anders H.

    2006-01-01

    Network effects is when a change at one place in the railway network results in changes elsewhere in the network – maybe even far away from the original change. Railway investments have network effects, and therefore, this paper describes the network effects and how these network effects can...... be examined by queuing time. This paper gives examples of network effects and describes the importance of the size of the analysis area and the connections between trains in the railway network....

  1. Analysis of Mean Transfer Delay on SCI Ring

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The scalable coherent interface (SCI) is an IEEE standard whose basic topology is ringlet, a kind of buffer insertion ring. SCI ring allows more than one message transfer concurrently, which brings difficulty on modeling SCI ring analytically.This paper presents an analytic expression on mean transfer delay using M/G/1 queuing model with non-preemptive priority. A preliminary performance study is also presented.

  2. A High-Speed Active Switch Routing Architecture

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, combining with active networks, we design a new kind of programmable routing switch architecture to provide a common intelligent switch platform for multi-protocol switching and multi-service accessing. We elaborate how programmable switch and network intelligence are achieved, and how packets are classified, queued and scheduled. We point out that edge intelligence and network software are the tendency for the development of future networks.

  3. Rationing with baselines

    DEFF Research Database (Denmark)

    Hougaard, Jens Leth; Moreno-Ternero, Juan D.; Østerdal, Lars Peter Raahave

    2013-01-01

    We introduce a new operator for general rationing problems in which, besides conflicting claims, individual baselines play an important role in the rationing process. The operator builds onto ideas of composition, which are not only frequent in rationing, but also in related problems...... such as bargaining, choice, and queuing. We characterize the operator and show how it preserves some standard axioms in the literature on rationing. We also relate it to recent contributions in such literature....

  4. Formalisms for Specifying Markovian Population Models

    Science.gov (United States)

    Henzinger, Thomas A.; Jobstmann, Barbara; Wolf, Verena

    We compare several languages for specifying Markovian population models such as queuing networks and chemical reaction networks. These languages —matrix descriptions, stochastic Petri nets, stoichiometric equations, stochastic process algebras, and guarded command models— all describe continuous-time Markov chains, but they differ according to important properties, such as compositionality, expressiveness and succinctness, executability, ease of use, and the support they provide for checking the well-formedness of a model and for analyzing a model.

  5. Chaotic nature of mesh networks with distributed routing

    Science.gov (United States)

    Rucinski, Andrzej; Drexel, Peter G.; Dziurla, Barbara

    1991-04-01

    This paper proposes a new formalism to classify distributed systems. Traditional tools like queuing theory Markov chains and perturbance analysis assume linear system behaviors and are used to characterize steady state operation meaningful only if the dynamic transients are disregarded. An approach based upon methodology used to characterize nonlinear chaotic systems is introduced. A simulation model a mesh of processors with distributed routing is used to demonstrate typical behaviors including chaos.

  6. Covert Bits Through Queues

    OpenAIRE

    Mukherjee, Pritam; Ulukus, Sennur

    2016-01-01

    We consider covert communication using a queuing timing channel in the presence of a warden. The covert message is encoded using the inter-arrival times of the packets, and the legitimate receiver and the warden observe the inter-departure times of the packets from their respective queues. The transmitter and the legitimate receiver also share a secret key to facilitate covert communication. We propose achievable schemes that obtain non-zero covert rate for both exponential and general queues...

  7. Optimizing Decisions in Web Services Orchestrations

    OpenAIRE

    Kattepur, Ajay; Benveniste, Albert; Jard, Claude

    2011-01-01

    International audience; Web services orchestrations conventionally employ exhaustive comparison of runtime quality of service (QoS) metrics for decision making. The ability to incorporate more complex mathematical packages are needed, especially in case of workflows for resource allocation and queuing systems. By modeling such optimization routines as service calls within orchestration specifications, techniques such as linear programming can be conveniently invoked by non-specialist workflow...

  8. Request Stream Control for the Access to Broadband Multimedia Educational Resources in the Distance Learning System

    Directory of Open Access Journals (Sweden)

    Irina Pavlovna Bolodurina

    2013-10-01

    Full Text Available This article presents a model of queuing system for broadband multimedia educational resources, as well as a model of access to a hybrid cloud system storage. These models are used to enhance the efficiency of computing resources in a distance learning system. An additional OpenStack control module has been developed to achieve the distribution of request streams and balance the load between cloud nodes.

  9. Marrakesh International Conference on Probability and Statistics

    CERN Document Server

    Ouassou, Idir; Rachdi, Mustapha

    2015-01-01

    This volume, which highlights recent advances in statistical methodology and applications, is divided into two main parts. The first part presents theoretical results on estimation techniques in functional statistics, while the second examines three key areas of application: estimation problems in queuing theory, an application in signal processing, and the copula approach to epidemiologic modelling. The book’s peer-reviewed contributions are based on papers originally presented at the Marrakesh International Conference on Probability and Statistics held in December 2013.

  10. Methods for Intelligent Mapping of the IPV6 Address Space

    Science.gov (United States)

    2015-03-01

    result in larger gains. To test this theory , RSI6 is modified to combine the previous two targeted probing techniques, which may provide a large... theory that organizations are subnetting on nibble boundaries, RSI6 is modified to operate under this premise. The goal is to see whether this method...notification is given to the user that the probe will not complete or return a result. Essentially, the probe request is queued waiting for the downed

  11. Detailed Maintenance Planning for Military Systems with Random Lead Times and Cannibalization

    Science.gov (United States)

    2014-12-01

    with IID-featured PE failures are studied using Queuing Theory [3, 4, 10]. However, this method cannot be used for detailed operational decision making...constant failure rates and therefore they were able to apply queue theory on maintenance and reliability study [3–7]. In the CAF reality, however, the...in a time period depends on the number of functioning PEs at the beginning of the period. Using the theory of Markov decision process (MDP), Zhang [8

  12. Distributed System of Processing of Data of Physical Experiments

    Science.gov (United States)

    Nazarov, A. A.; Moiseev, A. N.

    2014-11-01

    Complication of physical experiments and increasing volumes of experimental data necessitate the application of supercomputer and distributed computing systems for data processing. Design and development of such systems, their mathematical modeling, and investigation of their characteristics and functional capabilities is an urgent scientific and practical problem. In the present work, the characteristics of operation of such distributed system of processing of data of physical experiments are investigated using the apparatus of theory of queuing networks.

  13. A QoS-Aware Routing Protocol for Real-time Applications in Wireless Sensor Networks

    CERN Document Server

    Cherian, Mary

    2012-01-01

    The paper presents a quality of service aware routing protocol which provides low latency for high priority packets. Packets are differentiated based on their priority by applying queuing theory. Low priority packets are transferred through less energy paths. The sensor nodes interact with the pivot nodes which in turn communicate with the sink node. This protocol can be applied in monitoring context aware physical environments for critical applications.

  14. Research trends in existing technologies that are building blocks to the internet of things

    CSIR Research Space (South Africa)

    Dlodlo, N

    2013-07-01

    Full Text Available (FTP), Simple Mail Transfer Protocol (SMTP), Advanced Message Queuing protocol (AMQP), Extensible Messaging and Presence Protocol (XMPP), Message Queue Telemetry Transport (MQTT), Real Time Streaming Protocol (RTSP) and Simple Object Access... IP address but are allocated IP addresses at any point in time when a transaction has to occur. Network Address Translation (NAT) translates private addresses in one network into a public address going into another network. In dual stacking, IPv6...

  15. Broadcasting XORs: On the Application of Network Coding in Access Point-to-Multipoint Networks

    OpenAIRE

    Fouli, Kerim; Sergeev, Ivan; Maier, Martin; Casse, Jerome; Medard, Muriel

    2012-01-01

    We investigate network coding (NC) in access point-to-multi-point (PMP) broadcast networks. Characterized by a shared unicast upstream channel and a time-shared broadcast downstream channel, PMP networks are widely deployed in optical and wireless access networks. We develop a queuing-theoretic model of NC at the medium access control (MAC) sublayer and analyze the impact of NC on packet delay. Our analysis is validated through discrete-event simulation and demonstrates significant delay adva...

  16. Evaluating on Performance of Single-source Single-relay Sr-carq protocol in Tdma Networks with Raleigh Fading

    Directory of Open Access Journals (Sweden)

    Yongqiang Zhou

    2012-09-01

    Full Text Available This paper analyzes the performance of single-source and single-relay SR-CARQ protocol in TDMA wireless communication system. We establish its M/G/1 queuing model with vacations, and provide the expressions of its system time delay and saturation throughput. Then the analysis of theory and simulation results under the slow Raleigh fading channel show that under what conditions the SR-CARQ protocol is superior to its non-cooperative counterpart.

  17. Performance Comparison and Analysis of IP and MPLS Networks

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With the increasing need for Quality of Service(QoS),the traditional IP network is becoming less competitive. In order to give readers quantitative and convictive performance comparisons between IP and MPLS network,we choose Berkeleys NS-2 simulator[1] in our research on network throughput and end-to-end TCP behavior. Using NS-2 simulator,we analyze the performance of a network with MPLS Traffic Engineering(MPLS-TE).Specifically,the throughput and TCP end-to-end delay time under two different queuing algorithms are obtained and compared between the MPLS network and traditional IP network. We find that in the IP network using SFQ queuing algorithm will help traffic balance compared to the simple FIFO scheme,but it still can not utilize the available bandwidth,which in turn leads to the poor performance as in the FIFO case.With MPLS-TE, the throughput will be higher and the end-to-end TCP delay time remains almost the same even in heavy load case.We notice that if flows are isolated partially,using SFQ scheme will have a comparable performance as the fully isolation case using FIFO scheme in a MPLS network,and that if flows are isolated fully for FIFO and SFQ schemes,both will have the same result.Finally,we conclude that a better queuing algorithm will help reduce the label space requirement.

  18. Performance Comparison and Analysis of IP and MPLS Networks

    Institute of Scientific and Technical Information of China (English)

    LIUEr-wu; CAOMing-cui; 等

    2001-01-01

    With the increasing need for Quality of Service(QoS), the traditional IP network is becoming less com-petitive.In order to give readers quantitative and convictive performance comparisons between IP and MPLS net-work, we choose Berkeley's NS-2 simulator[1] in our research on network throughput and end-to-end TCP behavior.Using NS-2 simulator,we analyze the performance of a network with MPLS Traffic Engineering (MPLS-TE).Specifically, the throughput and TCP end-to-end delay time under two different queuing algorithms are obtained and compared between the MPLS network and traditional IP network .We find that in the IP network using SFQ queuing algorithm will help traffic balance compared to the simple FIFO scheme,but it still can ont utilize the available bandwidth,which in turn leads to the poor performance as in the FIFO case.With MPLS-TE,the throughput will be higher and the end-to-end TCP delay time remains almost the same even in heavy load case.We notice that if flows are isolated partially,using SFQ scheme will have a comparable performance as the fully isola-tion case using FIFO scheme in a MPLS network, and that if flows are isolated fully for FIFO and SFQ schemes, both will have the same result.Finally,we conclude that a better queuing algorithm will help reduce the label space requirement.

  19. Applied probability and stochastic processes. 2. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Feldman, Richard M. [Texas A and M Univ., College Station, TX (United States). Industrial and Systems Engineering Dept.; Valdez-Flores, Ciriaco [Sielken and Associates Consulting, Inc., Bryan, TX (United States)

    2010-07-01

    This book presents applied probability and stochastic processes in an elementary but mathematically precise manner, with numerous examples and exercises to illustrate the range of engineering and science applications of the concepts. The book is designed to give the reader an intuitive understanding of probabilistic reasoning, in addition to an understanding of mathematical concepts and principles. The initial chapters present a summary of probability and statistics and then Poisson processes, Markov chains, Markov processes and queuing processes are introduced. Advanced topics include simulation, inventory theory, replacement theory, Markov decision theory, and the use of matrix geometric procedures in the analysis of queues. Included in the second edition are appendices at the end of several chapters giving suggestions for the use of Excel in solving the problems of the chapter. Also new in this edition are an introductory chapter on statistics and a chapter on Poisson processes that includes some techniques used in risk assessment. The old chapter on queues has been expanded and broken into two new chapters: one for simple queuing processes and one for queuing networks. Support is provided through the web site http://apsp.tamu.edu where students will have the answers to odd numbered problems and instructors will have access to full solutions and Excel files for homework. (orig.)

  20. 城铁安全检查通过率分析及建模研究%Analysis and Modeling of Urban Rail Transit Safety Inspection Passing Rate

    Institute of Scientific and Technical Information of China (English)

    马玉姣; 刘凯

    2011-01-01

    Using queue theory, the paper elaborates on the principle and methods for the establishment of a queuing system model for urban rail transit passengers, focuses on optimizing the in-flowing passenger behavioral pattern and inbound queuing system to minimize expenditure, maximize operational benefit, and guarantee the passing capacity of incoming passenger safety inspection, and at the end applies the model to other of queuing system scenarios.%应用排队论原理,阐述建立乘客乘坐轨道交通过程的排队系统模型原理及思想,重点论述了高峰时期客流进站行为规律及进站排队系统的优化,以期最小的费用成本支出和最高的运营效益,解决进站安检通过能力问题,并应用该模型算法到其他服务问题的排队系统中.

  1. Hybrid Systems Modeling in Non Standard Queue and Optimization with the Simulation Approach in CNG Stations

    Directory of Open Access Journals (Sweden)

    Meysam Haddadi

    2012-07-01

    Full Text Available Modeling line in non standard way occurs when layout constraints and inappropriate placing customer is limited for taking customer service by the servant. The aim of this study is providing a mixed model for analyzing the system of non-standard line with Considering the limitations of the layout with Using the concepts and principles of queuing theory So that the main parameters of the model for this type of system can be calculated and The basis of queuing systems with non-standard parameters may be considered. In these nonstandard systems, because of special arrangement of servants, there are some delay times for giving services and exit. The use of simulation tools to demonstrate the relatively low efficiency of CNG (Compressed Natural Gas stations in Iran, To provide an optimum combination of servers (Fuel nozzle Also more efficient layout for the CNG stations has Studied. Manufacturing firms and service managers can use this model and evaluate and analysis their own system and get a better recognition of their system. One of the most widely used queuing systems in the country are CNG stations, in consideration high investment cost and land value in large cities, so we decided to studied on this area as one of the servicing activities.

  2. Performance Analysis of a Cluster-Based MAC Protocol for Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Jesús Alonso-Zárate

    2010-01-01

    Full Text Available An analytical model to evaluate the non-saturated performance of the Distributed Queuing Medium Access Control Protocol for Ad Hoc Networks (DQMANs in single-hop networks is presented in this paper. DQMAN is comprised of a spontaneous, temporary, and dynamic clustering mechanism integrated with a near-optimum distributed queuing Medium Access Control (MAC protocol. Clustering is executed in a distributed manner using a mechanism inspired by the Distributed Coordination Function (DCF of the IEEE 802.11. Once a station seizes the channel, it becomes the temporary clusterhead of a spontaneous cluster and it coordinates the peer-to-peer communications between the clustermembers. Within each cluster, a near-optimum distributed queuing MAC protocol is executed. The theoretical performance analysis of DQMAN in single-hop networks under non-saturation conditions is presented in this paper. The approach integrates the analysis of the clustering mechanism into the MAC layer model. Up to the knowledge of the authors, this approach is novel in the literature. In addition, the performance of an ad hoc network using DQMAN is compared to that obtained when using the DCF of the IEEE 802.11, as a benchmark reference.

  3. SISTEMUL DE AŞTEPTARE [SM / M /∞] CU FLUX SEMI-MARKOV. CRITERIUL DE MEDIERE

    Directory of Open Access Journals (Sweden)

    Iulia DAMIAN

    2015-12-01

    Full Text Available În articol sunt analizate reţelele semimarkoviene de servire şi este studiată convergenţa slabă în procesele de aşteptare în schema de mediere. De asemenea, este studiat criteriul de mediere a sistemului de aşteptare semi-Markov [SM / M /∞] prin evoluţia aleatoare şi folosind operatorul de compensaţie a procesului extins Markov de reînnoire.QUEUING SYSTEM WITH SEMI-MARKOV FLOW  [SM / M /∞]. AVERAGE SCHEME In this article study the queuing system where the input flow is described by a semi-Markov process, the service time is exponentially distributed. This article is about of the weak convergence in average scheme. It is study average scheme for semi-Markov queuing systems  [SM / M /∞] by a random evolution approach and using compensating operator of the corresponding extended Markov process.

  4. Multi-Flow Carrier Aggregation in Heterogeneous Networks: Cross-Layer Performance Analysis

    KAUST Repository

    Alorainy, Abdulaziz

    2017-02-09

    Multi-flow carrier aggregation (CA) has recently been considered to meet the increasing demand for high data rates. In this paper, we investigate the cross-layer performance of multi-flow CA for macro user equipments (MUEs) in the expanded range (ER) of small cells. We develop a fork/join (F/J) queuing analytical model that takes into account the time varying channels, the channel scheduling algorithm, partial CQI feedback and the number of component carriers deployed at each tier. Our model also accounts for stochastic packet arrivals and the packet scheduling mechanism. The analytical model developed in this paper can be used to gauge various packet-level performance parameters e.g., packet loss probability (PLP) and queuing delay. For the queuing delay, our model takes out-of-sequence packet delivery into consideration. The developed model can also be used to find the amount of CQI feedback and the packet scheduling of a particular MUE in order to offload as much traffic as possible from the macrocells to the small cells while maintaining the MUE\\'s quality of service (QoS) requirements.

  5. Proportional-integral and proportional-integral-derivative-based cyclic sleep controllers with anti-windup technique for energy-efficient and delay-aware passive optical networks

    Science.gov (United States)

    Kikuchi, Takahiro; Kubo, Ryogo

    2016-08-01

    In energy-efficient passive optical network (PON) systems, the increase in the queuing delays caused by the power-saving mechanism of optical network units (ONUs) is an important issue. Some researchers have proposed quality-of-service (QoS)-aware ONU cyclic sleep controllers in PON systems. We have proposed proportional (P) and proportional-derivative (PD)-based controllers to maintain the average queuing delay at a constant level regardless of the amount of downstream traffic. However, sufficient performance has not been obtained because of the sleep period limitation. In this paper, proportional-integral (PI) and proportional-integral-derivative (PID)-based controllers considering the sleep period limitation, i.e., using an anti-windup (AW) technique, are proposed to improve both the QoS and power-saving performance. Simulations confirm that the proposed controllers provide better performance than conventional controllers in terms of the average downstream queuing delay and the time occupancy of ONU active periods.

  6. Delay-aware adaptive sleep mechanism for green wireless-optical broadband access networks

    Science.gov (United States)

    Wang, Ruyan; Liang, Alei; Wu, Dapeng; Wu, Dalei

    2017-07-01

    Wireless-Optical Broadband Access Network (WOBAN) is capacity-high, reliable, flexible, and ubiquitous, as it takes full advantage of the merits from both optical communication and wireless communication technologies. Similar to other access networks, the high energy consumption poses a great challenge for building up WOBANs. To shot this problem, we can make some load-light Optical Network Units (ONUs) sleep to reduce the energy consumption. Such operation, however, causes the increased packet delay. Jointly considering the energy consumption and transmission delay, we propose a delay-aware adaptive sleep mechanism. Specifically, we develop a new analytical method to evaluate the transmission delay and queuing delay over the optical part, instead of adopting M/M/1 queuing model. Meanwhile, we also analyze the access delay and queuing delay of the wireless part. Based on such developed delay models, we mathematically derive ONU's optimal sleep time. In addition, we provide numerous simulation results to show the effectiveness of the proposed mechanism.

  7. Study of a New Quick-Charging Strategy for Electric Vehicles in Highway Charging Stations

    Directory of Open Access Journals (Sweden)

    Lixing Chen

    2016-09-01

    Full Text Available To solve the problem, because of which conventional quick-charging strategies (CQCS cannot meet the requirements of quick-charging for multiple types of electric vehicles (EV on highways where vehicle inflow is excessive, this paper proposed a new quick-charging strategy (NQCS for EVs: on the premise of not affecting those EVs being charged, the remaining power of the quick-charging pile with multiple power output interfaces is used to provide a synchronous charging service for EVs waiting in the queue. To verify the effectiveness of this strategy, a power distribution model of charging pile and a queuing model of charging station (CS were constructed. In addition, based on an actual highway service area where vehicle inflow is excessive during the simulation period (0:00–24:00, charging situations of CQCS and NQCS were respectively simulated in a charging station (CS, with different number of chargers, by basic queuing algorithm and an improved queuing algorithm. The simulation results showed that when the relative EV inflow is excessive, compared to CQCS, NQCS not only can reduce user waiting time, charging time, and stay time, but also can improve the utilisation rate of charging infrastructure and service capacity of CS and reduce the queue length of CS. At the same time, NQCS can reduce the impact on the power grid. In addition, in NQCS, the on-demand power distribution method is more efficient than the average power distribution method. Therefore, NQCS is more suitable for quick-charging for multiple types of EVs on highways where vehicle inflow is excessive.

  8. FACTORS INFLUENCING WAITING TIME IN OUTPATIENT PHARMACY OF LAGOS UNIVERSITY TEACHING HOSPITAL

    Directory of Open Access Journals (Sweden)

    Ndukwe Henry C.

    2011-10-01

    Full Text Available Time, money and expertise are resources that are indispensable to productivity, performance, efficiency, success and growth of any health institution. This research was aimed at identifying and measuring some of the factors influencing patient waiting time in an outpatient pharmacy. The study employed the use of time monitoring card and time study analysis to volunteered participants. A situation analysis conducted revealed an average of 167 minutes of waiting time. The dispensing time averaged 17.65 minutes, and 67.97% of total waiting time by the patient was due to delay components. The major delay components included patient queues for billing of prescription sheets, payment to the cashier and subsequent time wait before drugs are dispensed. The total waiting time for the dispensing process averaged 55.11 minutes. Generally, there were undue delays caused by the dispensing procedure with a 32.03% lag of processing components and operations in the pharmacy. Factors indentified to influence the outpatient waiting time included, queuing and queuing characteristics-type and integrity of queue, adherence to hospital visits and medication for special disease programs, dispensing time, average waiting time (service time plus queuing time, nature of illness or disease presentation, admission status of patient(s, accrued time from other health services provided to the patient prior to services provided by the pharmacist, incentives for providing efficient services, management structures and operational procedures of outpatient hospital pharmacy, implementation of legal rights on waiting time, inadequate treatment or dispensing facilities, technological innovations of automation and computerization , service efficiency and internal operational factors.

  9. Design of an IPTV Multicast System for Internet Backbone Networks

    Directory of Open Access Journals (Sweden)

    T. H. Szymanski

    2010-01-01

    Full Text Available The design of an IPTV multicast system for the Internet backbone network is presented and explored through extensive simulations. In the proposed system, a resource reservation algorithm such as RSVP, IntServ, or DiffServ is used to reserve resources (i.e., bandwidth and buffer space in each router in an IP multicast tree. Each router uses an Input-Queued, Output-Queued, or Crosspoint-Queued switch architecture with unity speedup. A recently proposed Recursive Fair Stochastic Matrix Decomposition algorithm used to compute near-perfect transmission schedules for each IP router. The IPTV traffic is shaped at the sources using Application-Specific Token Bucker Traffic Shapers, to limit the burstiness of incoming network traffic. The IPTV traffic is shaped at the destinations using Application-Specific Playback Queues, to remove residual network jitter and reconstruct the original bursty IPTV video streams at each destination. All IPTV traffic flows are regenerated at the destinations with essentially zero delay jitter and essentially-perfect QoS. The destination nodes deliver the IPTV streams to the ultimate end users using the same IPTV multicast system over a regional Metropolitan Area Network. It is shown that all IPTV traffic is delivered with essentially-perfect end-to-end QoS, with deterministic bounds on the maximum delay and jitter on each video frame. Detailed simulations of an IPTV distribution system, multicasting several hundred high-definition IPTV video streams over several essentially saturated IP backbone networks are presented.

  10. A model to create an efficient and equitable admission policy for patients arriving to the cardiothoracic ICU.

    Science.gov (United States)

    Yang, Muer; Fry, Michael J; Raikhelkar, Jayashree; Chin, Cynthia; Anyanwu, Anelechi; Brand, Jordan; Scurlock, Corey

    2013-02-01

    To develop queuing and simulation-based models to understand the relationship between ICU bed availability and operating room schedule to maximize the use of critical care resources and minimize case cancellation while providing equity to patients and surgeons. Retrospective analysis of 6-month unit admission data from a cohort of cardiothoracic surgical patients, to create queuing and simulation-based models of ICU bed flow. Three different admission policies (current admission policy, shortest-processing-time policy, and a dynamic policy) were then analyzed using simulation models, representing 10 yr worth of potential admissions. Important output data consisted of the "average waiting time," a proxy for unit efficiency, and the "maximum waiting time," a surrogate for patient equity. A cardiothoracic surgical ICU in a tertiary center in New York, NY. Six hundred thirty consecutive cardiothoracic surgical patients admitted to the cardiothoracic surgical ICU. None. Although the shortest-processing-time admission policy performs best in terms of unit efficiency (0.4612 days), it did so at expense of patient equity prolonging surgical waiting time by as much as 21 days. The current policy gives the greatest equity but causes inefficiency in unit bed-flow (0.5033 days). The dynamic policy performs at a level (0.4997 days) 8.3% below that of the shortest-processing-time in average waiting time; however, it balances this with greater patient equity (maximum waiting time could be shortened by 4 days compared to the current policy). Queuing theory and computer simulation can be used to model case flow through a cardiothoracic operating room and ICU. A dynamic admission policy that looks at current waiting time and expected ICU length of stay allows for increased equity between patients with only minimum losses of efficiency. This dynamic admission policy would seem to be a superior in maximizing case-flow. These results may be generalized to other surgical ICUs.

  11. The Impact of Increasing Staff Resources on Patient Flow in a Psychiatric Emergency Service.

    Science.gov (United States)

    Chepenik, Lara; Pinker, Edieal

    2017-05-01

    The study illustrates the use of approaches based on queuing theory to understand bottlenecks in patient flow. A queuing simulation was used to predict the potential benefits of additional clinical personnel on patient flow through a psychiatric emergency service (PES). A discrete-event simulation model was calibrated on the basis of two months of data collected in a PES. This model examined the effects of adding between .5 (half-time) and three additional providers to the 8 a.m. to 4 p.m. shift. The model showed that an addition of a half-time clinician produced the biggest change in patient flow metrics. Average length of stay was predicted to drop from 38.1 hours to 33.2 hours for patients who were awaiting hospitalization and from 13.7 to 9.0 hours for patients who were eventually discharged. The number of patients waiting to see a provider decreased by two-thirds between 8 a.m. and 4 p.m., and it decreased by one-half during the rest of the day, even though the number of clinical staff remained the same. Adding more providers failed to reduce these numbers much further. Adding more than a half-time provider also failed to significantly reduce boarding (remaining in the PES while awaiting hospitalization). Queuing simulation predicted a dramatic benefit to patient flow with a fairly small addition in clinician time, a benefit that persisted beyond the time during which the additional staff was on duty, especially when this staff was added during a period of high demand.

  12. Influences of clock resolution of bandwidth measurement on packet pair algorithm

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The packet pair algorithm[1],proposed by VanTacobsonand,was employed to measure the bottle-neck(link)bandwidth of a net work route by Carterand Crovella.The packet pair algorithm was provedcorrect theoretically by Lai and Baker[2].However,the definition of the packet pair algortithn is basedon ideal net work environments.The factors in thereal net work environments,such as queuing[3]andtraffic interference[4],are not considered.Themeasurements using the packet pair algorithm arenot accurate and stable.In th...

  13. Usage of Message Queueing Technologies in the ATLAS Distributed Data Management System

    Science.gov (United States)

    Calfayan, Philippe; Dongsong, Zang; Garonne, Vincent

    2011-12-01

    The ATLAS Distributed Data Management system is composed of semi-autonomous, heterogeneous, and independently designed subsystems. To achieve successful operation of such a system, the activities of the agents controlling the subsystems have to be coordinated. In addition, external applications can require to synchronize on events relative to data availability. A common way to proceed is to implement polling strategies within the distributed components, which leads to an increase of the load in the overall system. We describe an alternative based on notifications using standard message queuing. The application of this technology in the distributed system has been exercised.

  14. Performance Analysis of TCP-Reno and TCP-Sack in the Case of a Single Source

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This work explores the behavior of both TCP-Reno and TCP-Sack under a simple scenario, where a single TCP source transmits the packets continuously over a single bottleneck node characterized by its queue size, bandwidth and propagation delay. The analysis allows to derive the performance of TCP, the utilization tends to 75% of the bottleneck throughput when the bandwidth × propagation delay pipe becomes very large, while it tends to 100% when the queuing delays are predominant because the queue is never empty. In the transient analysis we show how the initial phase of the session can degrade the performances. These results are proved through simulation.

  15. High-performance architectures for high-radix switches.

    OpenAIRE

    2009-01-01

    Para beneficiarse de una reducción en la latencia así como disminuir tanto el consumo como el coste, el número óptimo de puertos de un conmutador ha ido aumentando a lo largo del tiempo. Sin embargo, las arquitecturas tradicionales se han quedado atrás bien por bajo rendimiento o bien por problemas de escalabilidad con el número de puertos. En esta Tesis se propone una nueva arquitectura de conmutador válida para conmutadores de elevado grado llamada Partitioned Crossbar Input Queued (PCI...

  16. Comparing two socially optimal work allocation rules when having a profit optimizing subcontractor with ample capacity

    DEFF Research Database (Denmark)

    Larsen, Christian

    2005-01-01

    We study a service system modelled as a single server queuing system where request for service either can be processed at the service system or by a subcontractor. In the former case the customer is incurred waiting costs but the service is free, while in the latter case the customer must pay....... The two work allocation rules are characterized by one being centralized and randomized while the other is decentralized and deterministic. From the subcontractors point of view the latter is preferred and under this rule he receives lesser requests but can charge a higher price compared to the former. We...

  17. How to Take HRMS Process Management to the Next Level with Workflow Business Event System

    Science.gov (United States)

    Rajeshuni, Sarala; Yagubian, Aram; Kunamaneni, Krishna

    2006-01-01

    Oracle Workflow with the Business Event System offers a complete process management solution for enterprises to manage business processes cost-effectively. Using Workflow event messaging, event subscriptions, AQ Servlet and advanced queuing technologies, this presentation will demonstrate the step-by-step design and implementation of system solutions in order to integrate two dissimilar systems and establish communication remotely. As a case study, the presentation walks you through the process of propagating organization name changes in other applications that originated from the HRMS module without changing applications code. The solution can be applied to your particular business cases for streamlining or modifying business processes across Oracle and non-Oracle applications.

  18. An adaptive linearizer for 16-QAM transmission over non-linear satellite channels

    Science.gov (United States)

    Shanmugan, K. Sam; Ruggles, M. J.

    An adaptive nonlinear equalization scheme that consists of a predistorter located at the transmitting earth station and a linear equalizer at the receiving earth station is described. Algorithms for automatically adjusting the predistorter and the linear equalizer are presented. The effectiveness of the scheme is evaluated using simulations. It is shown that the scheme improves the performance of a 16-queued access memory system operating over a typical satellite channel by minimizing degradations in the signal as it is transmitted over a band-limited satellite channel.

  19. 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

  20. 基于信任管理系统的可信路由器的设计与实现(英文)

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    This paper presents a scheme to perform QoS management and assure network security by using the trusted-router based on the Trust Management System.In this trusted-router,every IP packet is forwarded and queued by its trust value,which is the quantification of the network's expectation for this packet's and its owner's behavior in the network.We outline the algorithms to calculate the trust value of the trusted-router and the IP packet.We also introduce the trust-based QoS management algorithm and the deplo...

  1. Optimal Heavy-Traffic Queue Length Scaling in an Incompletely Saturated Switch

    OpenAIRE

    Maguluri, Siva Theja; Burle, Sai Kiran; Srikant, R.

    2016-01-01

    We consider an input queued switch operating under the MaxWeight scheduling algorithm. This system is interesting to study because it is a model for Internet routers and data center networks. Recently, it was shown that the MaxWeight algorithm has optimal heavy-traffic queue length scaling when all ports are uniformly saturated. Here we consider the case when an arbitrary number of ports are saturated (which we call the incompletely saturated case), and each port is allowed to saturate at a d...

  2. RabbitMQ essentials

    CERN Document Server

    Dossot, David

    2014-01-01

    This book is a quick and concise introduction to RabbitMQ. Follow the unique case study of Clever Coney Media as they progressively discover how to fully utilize RabbitMQ, containing clever examples and detailed explanations.Whether you are someone who develops enterprise messaging products professionally or a hobbyist who is already familiar with open source Message Queuing software and you are looking for a new challenge, then this is the book for you. Although you should be familiar with Java, Ruby, and Python to get the most out of the examples, RabbitMQ Essentials will give you the push y

  3. How Eye Workers Can Help Newly Blind People

    Directory of Open Access Journals (Sweden)

    Geert Vanneste

    2003-01-01

    Full Text Available 8 a.m. The hospital day begins. Eighty people are queuing at the eye clinic. Eye workers, Mary and Gerard, know they’ll be busy until late afternoon. First they must see the post-operative patients. Two older cataract patients have a very good outcome after surgery. A 9-year-old child operated on for congenital cataract has a doubtful result, and cannot see any hand movement. With outpatients beginning to knock at the door, Mary has to find something to say to this child’s mother.

  4. Speech recognition for the anaesthesia record during crisis scenarios

    DEFF Research Database (Denmark)

    Alapetite, Alexandre

    2008-01-01

    Introduction: This article describes the evaluation of a prototype speech-input interface to an anaesthesia patient record, conducted in a full-scale anaesthesia simulator involving six doctor-nurse anaesthetist teams. Objective: The aims of the experiment were, first, to assess the potential...... gathered from a questionnaire. Analysis of data was made by a method inspired by queuing theory in order to compare the delays associated to the two interfaces and to quantify the workload inherent to the memorisation of items to be entered into the anaesthesia record. Results: The experiment showed...

  5. Semi-Markov models control of restorable systems with latent failures

    CERN Document Server

    Obzherin, Yuriy E

    2015-01-01

    Featuring previously unpublished results, Semi-Markov Models: Control of Restorable Systems with Latent Failures describes valuable methodology which can be used by readers to build mathematical models of a wide class of systems for various applications. In particular, this information can be applied to build models of reliability, queuing systems, and technical control. Beginning with a brief introduction to the area, the book covers semi-Markov models for different control strategies in one-component systems, defining their stationary characteristics of reliability and efficiency, and uti

  6. Multi-Level Round-Robin Multicast Scheduling with Look-Ahead Mechanism

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    In this paper, we propose a multi-level round-robin multicast scheduling (MLRRMS) algorithm with look-ahead (LA) mechanism for N×N input-queued switches. Fan-out splitting is applied, where a multicast cell can be transferred to all its destinations over any number of cell times. The scheduler...... constructs the Traffic Matrix before each cell transmission based on the fan-out vectors of the cells in the queues. A scheduling pointer independently moves on each column of the Traffic Matrix in a round-robin fashion and returns the decision to the Decision Matrix. The sync procedure is carried out...

  7. Improved Multicast Traffic Scheduling Scheme in the Packet-Switching Systems

    Institute of Scientific and Technical Information of China (English)

    SONG Mei-na; SONG Jun-de; LI Hong-wen

    2004-01-01

    This paper proposes a new switching scheme of switch fabric, which is named Multicast-enabled Protocol Agnostic Forwarding Engine (M-PAFE). M-PAFE is a central scheduling crossbar-based switch fabric with embedded Combined Input and Output Queue from the queuing view. An extra switching path is dedicated for multicast cell processing in M-PAFE. And the simulation results are provided to evaluate the performance of M-PAFE in comparison with ESLIP, which is a well-known algorithm implemented in Cisco 12000 routers.

  8. Roundabouts Canada case study

    Energy Technology Data Exchange (ETDEWEB)

    Jamieson, M. [Ryerson Polytechnic Univ., Toronto, ON (Canada); Lenters, M. [Roundabouts Canada, Whitby, ON (Canada)

    2002-07-01

    A modern roundabout was constructed in the community of Ancaster, Ontario in response to growing complaints regarding speeding along the major roadway, and queuing on the minor roadway. The roundabout opened on October 25, 2002. The before and after speeds at the roundabout are being studied, and the fastest path characteristics are assessed in an effort to determine whether the predicted fastest path data correlates with the in-service operating speeds. The speed at R1, R2 and R3 locations on the east west, and north south approaches are measured. tabs., figs.

  9. Analysis and optimization of delays in networked control systems

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The minimization problem of time delays in networked control system (NCS) is concered, which is a hot area of such research field. First, some analysis and comments on time-delayed NCS model listed in previous work are given.Then, time delay minimization problem based on average behavior of network queuing delay is presented. Under fixed routing scheme and certain optimization performance indexes, the delay minimization problem is translated into convex optimization problem. And the solution of the delay minimization problems is attained through optimized allocation of flow rates among network links.

  10. Computer-communication networks

    CERN Document Server

    Meditch, James S

    1983-01-01

    Computer- Communication Networks presents a collection of articles the focus of which is on the field of modeling, analysis, design, and performance optimization. It discusses the problem of modeling the performance of local area networks under file transfer. It addresses the design of multi-hop, mobile-user radio networks. Some of the topics covered in the book are the distributed packet switching queuing network design, some investigations on communication switching techniques in computer networks and the minimum hop flow assignment and routing subject to an average message delay constraint

  11. Production Planning with Load Dependent Lead Times

    DEFF Research Database (Denmark)

    Pahl, Julia

    2005-01-01

    Lead times impact the performance of the supply chain significantly. Although there is a large literature concerning queuing models for the analysis of the relationship between capacity utilization and lead times, and there is a substantial literature concerning control and order release policies...... that take lead times into consideration, there have been only few papers describing models at the aggregate planning level that recognize the relationship between the planned utilization of capacity and lead times. In this paper we provide an in-depth discussion of the state-of-the art in this literature...

  12. Researches on Active Queue Management%主动队列管理机制研究

    Institute of Scientific and Technical Information of China (English)

    李方敏; 叶澄清; 李仁发

    2001-01-01

    Currently,there are two methods suggested to handle congestion. The first approach uses packet or link scheduling on multiple logical or physical queues to explicitly reserve and allocate output bandwidth to each class of traffic. The second approach,called Active Queue management,uses advanced packet queuing disciplines on an outbound queue of a router to actively avoid congestion with the help of cooperative traffic sources. On the basis of analyzing the two approaches ,in order to efficiently support flow-controlled contnuous multimedia flows,we compare and analyze RED,FRED,CBT,D-CBT. Finally,we point out the shortcomings and the next research topic.

  13. Data management system performance modeling

    Science.gov (United States)

    Kiser, Larry M.

    1993-01-01

    This paper discusses analytical techniques that have been used to gain a better understanding of the Space Station Freedom's (SSF's) Data Management System (DMS). The DMS is a complex, distributed, real-time computer system that has been redesigned numerous times. The implications of these redesigns have not been fully analyzed. This paper discusses the advantages and disadvantages for static analytical techniques such as Rate Monotonic Analysis (RMA) and also provides a rationale for dynamic modeling. Factors such as system architecture, processor utilization, bus architecture, queuing, etc. are well suited for analysis with a dynamic model. The significance of performance measures for a real-time system are discussed.

  14. Exploratory Analysis of a GGSN’s PDP Context Signaling Load

    Directory of Open Access Journals (Sweden)

    Florian Metzger

    2014-01-01

    Full Text Available This paper takes an exploratory look on control plane signaling in a mobile cellular core network. In contrast to most contributions in this field, our focus does not lie on the wireless or user-oriented parts of the network, but on signaling in the core network. In an investigation of core network data we take a look at statistics related to GTP tunnels and their signaling. Based on the results thereof we propose a definition of load at the GGSN and create an initial load queuing model. We find signs of user devices putting burden on the core network through their behavior.

  15. Impact of Picocells on the Capacity and Energy Efficiency of Mobile Networks

    DEFF Research Database (Denmark)

    Saker, Louai; Micallef, Gilbert; Elayoubi, S. E.;

    2012-01-01

    . In the first section of the study, a theoretical analysis for the Erlang-like capacity of a network, considering a uniform topology and traffic, is performed, using queuing theory analysis, namely Processor Sharing queues. Results show that in all cases the deployment of picocells improve the performance...... of the network, however the energy efficiency is noted to be dependent on the deployment scenario considered. In the second part of the study, a more realistic scenario with non-uniform topology and traffic is considered, which is carried out through a large-scale system level simulator. Results show...

  16. Fast combinative volume rendering by indexed data structure

    Institute of Scientific and Technical Information of China (English)

    孙文武; 王文成; 吴恩华

    2001-01-01

    It is beneficial to study the interesting contents in a data set by combining and rendering variouscontents of the data. In this regard, an indexed data structure is proposed to facilitate the reorganization of data so that the contents of the data can be combined conveniently and only the selected contents in the data are processed for rendering. Based on the structure, the cells of different contents can be queued up easily so that the volume rendering can be conducted more accurately and quickly. Experimental results show that the indexed data structure is very efficient in improving combinative volume rendering.

  17. Banksy: The Bristol legacy

    OpenAIRE

    Gough, P.

    2012-01-01

    In the summer of 2009 Bristol saw a remarkable phenomenon that made international news. An estimated 300,000 people queued for hours, often in pouring rain, for admission to the city’s museum & art gallery. They had been attracted by the media hype surrounding an exhibition ambiguously entitled ‘Banksy vs the Bristol Museum’. There have been many celebratory books about Banksy, but this is the first non-partisan documentation of the Bristol event and an attempt to assess its local and wider i...

  18. Robust Broadcast-Communication Control of Electric Vehicle Charging

    CERN Document Server

    Turitsyn, Konstantin; Backhaus, Scott; Chertkov, Misha

    2010-01-01

    The anticipated increase in the number of plug-in electric vehicles (EV) will put additional strain on electrical distribution circuits. Many control schemes have been proposed to control EV charging. Here, we develop control algorithms based on randomized EV charging start times and simple one-way broadcast communication allowing for a time delay between communication events. Using arguments from queuing theory and statistical analysis, we seek to maximize the utilization of excess distribution circuit capacity while keeping the probability of a circuit overload negligible.

  19. On the Impact of Multi-User Traffic Dynamics on Low Latency Communications

    DEFF Research Database (Denmark)

    Gerardino, Guillermo Andrés Pocovi; Pedersen, Klaus I.; Alvarez, Beatriz Soret;

    2016-01-01

    In this paper we study the downlink latency performance in a multi-user cellular network. We use a flexible 5G radio frame structure, where the TTI size is configurable on a per-user basis according to their specific service requirements. Results show that at low system loads using a short TTI (e...... efficiency) provide better performance as these better cope with the non-negligible queuing delay. The presented results allow to conclude that support for scheduling with different TTI sizes is important for LLC and should be included in the future 5G....

  20. Impact of clinical surveillance during a foot-and-mouth disease epidemic

    DEFF Research Database (Denmark)

    Hisham Beshara Halasa, Tariq; Boklund, Anette

    The objectives of this study were to assess, whether the current surveillance capacity is sufficient to fulfill EU and Danish regulations to control a hypothetical foot-and-mouth disease (FMD) epidemic in Denmark, and whether enlarging the protection and/or surveillance zones could reduce epidemic...... duration, number of infected herds and the economic losses from an epidemic. The stochastic spatial simulation model DTU-DADS was enhanced to include simulation of surveillance of herds within the protection and surveillance zones and the model was used to model spread of FMD between herds. A queuing...

  1. 希捷Barracuda 7200.7 SATA

    Institute of Scientific and Technical Information of China (English)

    吴敌

    2004-01-01

    这款编号为ST3160023AS的希捷Barracuda 7200.7 SATA硬盘容量为160GB,其单碟容量为80GB.采用2碟4磁头物理架构,集成8MB缓存,并且支持NCQ (Native Command Queuing)指令。NCQ指令是一组用于规划磁盘访问的优化指令它可将无序的磁盘访问重新排列顺

  2. A CENTRAL-STAGE BUFFERED THREE-STAGE CLOS SWITCHING FABRIC AND THE SCHEDULING ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    Hu Yuxiang; Ma Xiangjie; Lan Julong; Wang Haoxue

    2009-01-01

    Current MSM switching fabric has poor performance under unbalanced traffic. This paper presents an alternative, novel Central-stage Buffered Three-stage Clos switching (CB-3Clos) fabric and proves that this fabric can emulate output queuing switch without any speedup. By analyzing the condition to satisfy the central-stage load-balance, this paper also proposes a Central-stage Load-balanced-based Distributed Scheduling algorithm (CLDS) for CB-3Clos. The results show that, compared with Concurrent Round-Robin based Dispatching (CRRD) algorithm based on MSM, CLDS algorithm has high throughput irrespective with the traffic model and better performance in mean packet delay.

  3. A SCHEDULING ALGORITHM USING COMPENSATING ROUND ROBIN IN PACKET—SWTICHING BROADBAND NETWORKS

    Institute of Scientific and Technical Information of China (English)

    LanJulong; WangBinqiang; 等

    2002-01-01

    A new approximation of fair queuing called Comensating Round Robin(CRR)ia presented in this paper.The algorithm uses packet-by-packet scheduler with a compensating measure.It achieves good fairness in terms of throrghput ,requires onlyO(1)time complexity to process a packet ,and is simple enough to be implemented in hardware.After the performances are analyzed ,the fairness and is simple enough to be implemented in hardware.After the performances are that the CRR can effectively isolate the effects of contending sources.

  4. A SCHEDULING ALGORITHM USING COMPENSATING ROUND ROBIN IN PACKET-SWTICHING BROADBAND NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Lan Julong; Wang Binqiang; Li Ou; Wu Jiangxing

    2002-01-01

    A new approximation of fair queuing called Compensating Round Robin (CRR)is presented in this paper. The algorithm uses packet-by-packet scheduler with a compensating measure. It achieves good fairness in terms of throughput, requires only O(1) time complexity to process a packet, and is simple enough to be implemented in hardware. After the performances are analyzed, the fairness and packet loss rate of the algorithm are simulated. Simulation results show that the CRR can effectively isolate the effects of contending sources.

  5. Operations Research – Tools & Techniques

    OpenAIRE

    Sreeramana Aithal

    2017-01-01

    Chapter 1 : Introduction to Operations Research   Chapter 2 : Linear Programming (LP)   Chapter  3 : Graphical Method in LP   Chapter  4 :  Simplex Method in LP   Chapter  5 :  Transportation Problems   Chapter  6 :  Assignment Problems   Chapter  7 :  Network Scheduling   Chapter  8 :  Game Theory   Chapter  9 :  Queuing Theory   Chapter  10 :  Markov Analysis   Chapter  11 :  Simulation Techniques   Chap...

  6. Reliability of fiber optic local and the other area networks (Poster Paper)

    Science.gov (United States)

    Grochowski, Lucjan

    1992-10-01

    Fault tolerance determines reliability of local, wide, and metropolitan area networks. Carried- out considerations are addressed to reliability evaluation of the classical, and the enhanced performance double rings, which are configurated according to ShuffleNet interconnection pattern realized by the use of wavelengths dependent signals. The considered multi-channel optical networks are modeled applying the Queuing Theory: the Continuous Time Markov Chains. Introduced models allow to determine in the data networks Mean Time to Failure, Data Throughput, and Time Delay. The results are implemented for performance simulation of advanced fiber optic data networks oriented towards High Speed Data Communications.

  7. A Single-Server Queue with Markov Modulated Service Times

    OpenAIRE

    1999-01-01

    We study an M/MMPP/1 queuing system, where the arrival process is Poisson and service requirements are Markov modulated. When the Markov Chain modulating service times has two states, we show that the distribution of the number-in-system is a superposition of two matrix-geometric series and provide a simple algorithm for computing the rate and coefficient matrices. These results hold for both finite and infinite waiting space systems and extend results obtained in Neuts [5] and Naoumov [4]. N...

  8. Robust broadcast-communication control of electric vehicle charging

    Energy Technology Data Exchange (ETDEWEB)

    Chertkov, Michael [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory; Sulc, Petr [Los Alamos National Laboratory; Backhaus, Scott [Los Alamos National Laboratory

    2010-01-01

    The anticipated increase in the number of plug-in electric vehicles (EV) will put additional strain on electrical distribution circuits. Many control schemes have been proposed to control EV charging. Here, we develop control algorithms based on randomized EV charging start times and simple one-way broadcast communication allowing for a time delay between communication events. Using arguments from queuing theory and statistical analysis, we seek to maximize the utilization of excess distribution circuit capacity while keeping the probability of a circuit overload negligible.

  9. The Joint Control of Variable Speed and On-Ramp Metering for Urban Expressway

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The traffic performance of urban expressway is subject to non-recurring and recurring events, which may cause heavy congestion and vehicles long queuing on ramps. The low performance may bring more traffic delay to the whole network of urban road. This paper presents a new method, the joint control of variable speed control and on-ramp metering, which attempts to improve the level of traffic operations on urban expressway. By analyzing traffic flow on urban expressway, an optimum control strategy of variable speed and on-ramp metering is established in the paper.``

  10. a Markov-Process Inspired CA Model of Highway Traffic

    Science.gov (United States)

    Wang, Fa; Li, Li; Hu, Jian-Ming; Ji, Yan; Ma, Rui; Jiang, Rui

    To provide a more accurate description of the driving behaviors especially in car-following, namely a Markov-Gap cellular automata model is proposed in this paper. It views the variation of the gap between two consequent vehicles as a Markov process whose stationary distribution corresponds to the observed gap distribution. This new model provides a microscopic simulation explanation for the governing interaction forces (potentials) between the queuing vehicles, which cannot be directly measurable for traffic flow applications. The agreement between empirical observations and simulation results suggests the soundness of this new approach.

  11. Stochastic evolutions of dynamic traffic flow modeling and applications

    CERN Document Server

    Chen, Xiqun (Michael); Shi, Qixin

    2015-01-01

    This book reveals the underlying mechanisms of complexity and stochastic evolutions of traffic flows. Using Eulerian and Lagrangian measurements, the authors propose lognormal headway/spacing/velocity distributions and subsequently develop a Markov car-following model to describe drivers’ random choices concerning headways/spacings, putting forward a stochastic fundamental diagram model for wide scattering flow-density points. In the context of highway onramp bottlenecks, the authors present a traffic flow breakdown probability model and spatial-temporal queuing model to improve the stability and reliability of road traffic flows. This book is intended for researchers and graduate students in the fields of transportation engineering and civil engineering.

  12. Delay Bound: Fractal Traffic Passes through Network Servers

    Directory of Open Access Journals (Sweden)

    Ming Li

    2013-01-01

    Full Text Available Delay analysis plays a role in real-time systems in computer communication networks. This paper gives our results in the aspect of delay analysis of fractal traffic passing through servers. There are three contributions presented in this paper. First, we will explain the reasons why conventional theory of queuing systems ceases in the general sense when arrival traffic is fractal. Then, we will propose a concise method of delay computation for hard real-time systems as shown in this paper. Finally, the delay computation of fractal traffic passing through severs is presented.

  13. [Waiting time for treatment shall be calculated correctly].

    Science.gov (United States)

    Pedersen, Jørgen Ejler

    2011-05-23

    Every system is perfectly designed to achieve the results it gets and in the Danish health care system there is a significant waiting time for the patients. If we want this result to change, we have to change something in the system, but before we do that, we need to understand the system. With queuing theory as a frame of reference, the anatomy and physiology of waiting time is illuminated in order to bring additional knowledge into the design of systems in health care.

  14. MATHEMATICAL SOLUTIONS OF VEHIULAR DELAY COMPONENTS AT SIGNALIZED INTERSECTIONS BASED ON APPROXIMATE CALCULATION METHOD

    Directory of Open Access Journals (Sweden)

    Halim CEYLAN

    2007-02-01

    Full Text Available This study develops approximate mathematical expressions for delay components at signalized intersections. Delay components are solved with the coordinate transformation method. The performance indicators for the signalized intersection are determined as an oversaturated and under saturated cases. During the analysis, the steady-state and the deterministic queuing theory are investigated first, and then time-dependent transformation is made. Developed model, called YHM, is applied to an example signalized intersection. Results are compared with the current situation and the Webster method. YHM is improved the intersection performance by about 500 % for this example. Moreover, signal parameters are significantly differs from the current and Webster signal control.

  15. Review of modeling approaches for emergency department patient flow and crowding research.

    Science.gov (United States)

    Wiler, Jennifer L; Griffey, Richard T; Olsen, Tava

    2011-12-01

    Emergency department (ED) crowding is an international phenomenon that continues to challenge operational efficiency. Many statistical modeling approaches have been offered to describe, and at times predict, ED patient load and crowding. A number of formula-based equations, regression models, time-series analyses, queuing theory-based models, and discrete-event (or process) simulation (DES) models have been proposed. In this review, we compare and contrast these modeling methodologies, describe the fundamental assumptions each makes, and outline the potential applications and limitations for each with regard to usability in ED operations and in ED operations and crowding research. © 2011 by the Society for Academic Emergency Medicine.

  16. Quantifying Cyber-Resilience Against Resource-Exhaustion Attacks

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Glenn A.; Griswold, Richard L.; Beech, Zachary W.

    2014-07-11

    Resilience in the information sciences is notoriously difficult to define much less to measure. But in mechanical engi- neering, the resilience of a substance is mathematically defined as the area under the stress vs. strain curve. We took inspiration from mechanics in an attempt to define resilience precisely for information systems. We first examine the meaning of resilience in language and engineering terms and then translate these definitions to information sciences. Then we tested our definitions of resilience for a very simple problem in networked queuing systems. We discuss lessons learned and make recommendations for using this approach in future work.

  17. Network performance analysis

    CERN Document Server

    Bonald, Thomas

    2013-01-01

    The book presents some key mathematical tools for the performance analysis of communication networks and computer systems.Communication networks and computer systems have become extremely complex. The statistical resource sharing induced by the random behavior of users and the underlying protocols and algorithms may affect Quality of Service.This book introduces the main results of queuing theory that are useful for analyzing the performance of these systems. These mathematical tools are key to the development of robust dimensioning rules and engineering methods. A number of examples i

  18. Endogenous scheduling preferences and congestion

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Small, Kenneth

    2010-01-01

    Dynamic models of congestion so far rely on exogenous scheduling preferences of travelers, based for example on disutility of deviation from a preferred departure or arrival time for a trip. This paper provides a more fundamental view in which travelers derive utility just from consumption...... and leisure, but agglomeration economies at home and at work lead to scheduling preferences forming endogenously. Using bottleneck congestion technology, we obtain an equilibrium queuing pattern consistent with a general version of the Vickrey bottleneck model. However, the policy implications are different...

  19. Network Congestion Control with Markovian Multipath Routing

    CERN Document Server

    Cominetti, Roberto

    2011-01-01

    In this paper we consider an integrated model for TCP/IP protocols with multipath routing. The model combines a Network Utility Maximization for rate control based on end-to-end queuing delays, with a Markovian Traffic Equilibrium for routing based on total expected delays. We prove the existence of a unique equilibrium state which is characterized as the solution of an unconstrained strictly convex program. A distributed algorithm for solving this optimization problem is proposed, with a brief discussion of how it can be implemented by adapting the current Internet protocols.

  20. How to Take HRMS Process Management to the Next Level with Workflow Business Event System

    Science.gov (United States)

    Rajeshuni, Sarala; Yagubian, Aram; Kunamaneni, Krishna

    2006-01-01

    Oracle Workflow with the Business Event System offers a complete process management solution for enterprises to manage business processes cost-effectively. Using Workflow event messaging, event subscriptions, AQ Servlet and advanced queuing technologies, this presentation will demonstrate the step-by-step design and implementation of system solutions in order to integrate two dissimilar systems and establish communication remotely. As a case study, the presentation walks you through the process of propagating organization name changes in other applications that originated from the HRMS module without changing applications code. The solution can be applied to your particular business cases for streamlining or modifying business processes across Oracle and non-Oracle applications.