WorldWideScience

Sample records for single server queues

  1. A unifying conservation law for single server queues.

    NARCIS (Netherlands)

    U. Ayesta (Urtzi)

    2005-01-01

    textabstractIn this paper we develop a conservation law for a work conserving multi-class $GI/GI/1$ queue operating under a general scheduling discipline. In the context of single-class queues, conservation laws have been obtained for both non-anticipating and anticipating disciplines with general

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

    Directory of Open Access Journals (Sweden)

    Najeeb Al-Matar

    2009-01-01

    examine a single-server queue with bulk input and secondary work during server's multiple vacations. When the buffer contents become exhausted the server leaves the system to perform some diagnostic service of a minimum of L jobs clustered in packets of random sizes (event A. The server is not supposed to stay longer than T units of time (event B. The server returns to the system when A or B occurs, whichever comes first. On the other hand, he may not break service of a packet in a middle even if A or B occurs. Furthermore, the server waits for batches of customers to arrive if upon his return the queue is still empty. We obtain a compact and explicit form functional for the queueing process in equilibrium.

  3. Iterative method of analysis of single queue, multi-server with limited ...

    African Journals Online (AJOL)

    In this paper, analysis of single queue, multi-server with limited system capacity under first come first served discipline was carried out using iterative method. The arrivals of customers and service times of customers are assumed poisson and exponential distributions respectively. This queuing model is an extension of ...

  4. A single-server queue with random accumulation level

    Directory of Open Access Journals (Sweden)

    Jewgeni H. Dshalalow

    1991-01-01

    The author establishes an ergodicity criterion for both the queueing process with continuous time parameter and the imbedded process. Under this criterion, the author obtains explicit formulas for the stationary distributions of both processes by using semi-regenerative techniques.

  5. A tandem queue with delayed server release

    NARCIS (Netherlands)

    Nawijn, W.M.

    1997-01-01

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

  6. Computation of a near-optimal service policy for a single-server queue with homogeneous jobs

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Larsen, Christian

    2000-01-01

    We present an algorithm for computing a near optimal service policy for a single-server queueing system when the service cost is a convex function of the service time. The policy has state-dependent service times, and it includes the options to remove jobs from the system and to let the server...

  7. Computation of a near-optimal service policy for a single-server queue with homogeneous jobs

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Larsen, Christian

    2001-01-01

    We present an algorithm for computing a near-optimal service policy for a single-server queueing system when the service cost is a convex function of the service time. The policy has state-dependent service times, and it includes the options to remove jobs from the system and to let the server...

  8. A tandem queue with delayed server release

    OpenAIRE

    Nawijn, W.M.

    1997-01-01

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

  9. Computing a constrained control policy for a single-server queueing system

    DEFF Research Database (Denmark)

    Larsen, Christian

    n different processing times. Hence, we must subdivide the infinite state space into n disjoint sets and for each set decide which processing time to use. We show how to derive a mathematical expression for the long-run average cost per time unit. We also present an algorithm to find the optimal......We consider a single-server queueing system designed to serve homogeneous jobs. The jobs arrive to the system after a Poisson process and all processing times are deterministic. There is a set-up cost for starting up production and a holding cost rate is incurred for each job present. Also......, there is a service cost per job, which is a convex function of the service time. The control policy specifies when the server is on or off. It also specifies the state-dependent processing times. In order to avoid a very detailed control policy (which could be hard to implement) we will only allow the server to use...

  10. Single-Server Queueing System with Markov-Modulated Arrivals and Service Times

    OpenAIRE

    Dimitrov, Mitko

    2011-01-01

    Key words: Markov-modulated queues, waiting time, heavy traffic. Markov-modulated queueing systems are those in which the input process or service mechanism is influenced by an underlying Markov chain. Several models for such systems have been investigated. In this paper we present heavy traffic analysis of single queueing system with Poisson arrival process whose arrival rate is a function of the state of Markov chain and service times depend on the state of the same Markov chain at the e...

  11. Note on a tandem queue with delayed server release

    NARCIS (Netherlands)

    Nawijn, W.M.

    2000-01-01

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

  12. Tandem queue with server slow-down

    NARCIS (Netherlands)

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

    2007-01-01

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

  13. Computation of a near-optimal service policy for a single-server queue with homogeneous jobs

    DEFF Research Database (Denmark)

    Johansen, Søren Glud; Larsen, Christian

    2001-01-01

    We present an algorithm for computing a near-optimal service policy for a single-server queueing system when the service cost is a convex function of the service time. The policy has state-dependent service times, and it includes the options to remove jobs from the system and to let the server...... be off. The systems' semi-Markov decision model has infinite action sets for the positive states. We design a new tailor-made policy-iteration algorithm for computing a policy for which the long-run average cost is at most a positive tolerance above the minimum average cost. For any positive tolerance...... our algorithm computes the desired policy in a finite (and small) number of iterations. The number is five for the numerical example used in the paper to illustrate results obtained by the algorithm....

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

    NARCIS (Netherlands)

    Abhishek; M.A.A. Boon (Marko); O.J. Boxma (Onno); R. Núñez Queija (Rudesindo)

    2017-01-01

    htmlabstractWe investigate the transient and stationary queue-length distributions of a class of service systems with correlated service times. The classical MX/G/1 queue with semi-Markov service times is the most prominent example in this class and serves as a vehicle to display

  15. Analysis of Single-Server Queue with Phase-Type Service and Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Sergey A. Dudin

    2016-01-01

    Full Text Available We propose a queueing model suitable, for example, for modelling operation of nodes of sensor networks. The sensor node senses a random field and generates packets to be transmitted to the central node. The sensor node has a battery of a finite capacity and harvests energy during its operation from outside (using solar cells, wind turbines, piezoelectric cells, etc.. We assume that, generally speaking, service (transmission of a packet consists of a random number of phases and implementation of each phase requires a unit of energy. If the battery becomes empty, transmission is failed. To reduce the probability of forced transmission termination, we suggest that the packet can be accepted for transmission only when the number of energy units is greater than or equal to some threshold. Under quite general assumptions about the pattern of the arrival processes of packets and energy, we compute the stationary distributions of the system states and the waiting time of a packet in the system and numerically analyze performance measures of the system as functions of the threshold. Validity of Little’s formula and its counterpart is verified.

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

    NARCIS (Netherlands)

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

    2005-01-01

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

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

    NARCIS (Netherlands)

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

    2005-01-01

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

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

    NARCIS (Netherlands)

    J.W. Cohen

    1995-01-01

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

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  20. A Central Limit Theorem for Markov-Modulated Infinite-Server Queues

    NARCIS (Netherlands)

    J.G. Blom (Joke); K.E.E.S deTurck; M.R.H. Mandjes (Michel); A. Dudin; K.E.E.S deTurck

    2013-01-01

    textabstractThis paper studies an infinite-server queue in a Markov environment, that is, an infinite-server queue with arrival rates and service times depending on the state of a Markovian background process. Scaling the arrival rates $\\lambda_i$ by a factor $N$ and the rate $q_{ij}$ of the

  1. Central Limit Theorems for Markov-modulated infinite-server queues

    NARCIS (Netherlands)

    J.G. Blom (Joke); K.E.E.S deTurck; M.R.H. Mandjes (Michel)

    2013-01-01

    textabstractThis paper studies an infinite-server queue in a Markov environment, that is, an infinite-server queue with arrival rates and service times depending on the state of an independently evolving Markovian background process. Scaling the arrival rates $\\lambda_i$ by a factor $N$ and the

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

    Science.gov (United States)

    Kempa, Wojciech M.

    2017-12-01

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

  3. Many-server queues with customer abandonment: Numerical analysis of their diffusion model

    OpenAIRE

    Dai, J. G.; He, Shuangchi

    2013-01-01

    We use a multidimensional diffusion process to approximate the dynamics of a queue served by many parallel servers. Waiting customers in this queue may abandon the system without service. To analyze the diffusion model, we develop a numerical algorithm for computing its stationary distribution. A crucial part of the algorithm is choosing an appropriate reference density. Using a conjecture on the tail behavior of the limit queue length process, we propose a systematic approach to constructing...

  4. Queueing system analysis of multi server model at XYZ insurance company in Tasikmalaya city

    Science.gov (United States)

    Muhajir, Ahmad; Binatari, Nikenasih

    2017-08-01

    Queueing theory or waiting line theory is a theory that deals with the queue process from the customer comes, queue to be served, served and left on service facilities. Queue occurs because of a mismatch between the numbers of customers that will be served with the available number of services, as an example at XYZ insurance company in Tasikmalaya. This research aims to determine the characteristics of the queue system which then to optimize the number of server in term of total cost. The result shows that the queue model can be represented by (M/M/4):(GD/∞/∞), where the arrivals are Poisson distributed while the service time is following exponential distribution. The probability of idle customer service is 2,39% of the working time, the average number of customer in the queue is 3 customers, the average number of customer in a system is 6 customers, the average time of a customer spent in the queue is 15,9979 minutes, the average time a customer spends in the system is 34,4141 minutes, and the average number of busy customer servicer is 3 server. The optimized number of customer service is 5 servers, and the operational cost has minimum cost at Rp 4.323.

  5. A note on many-server queueing systems with ordered entry, with an application to conveyor theory

    NARCIS (Netherlands)

    Nawijn, W.M.

    1983-01-01

    Consider a many-server queueing system in which the servers are numbered. If a customer arrives when two or more servers are idle he selects the server with lowest index (this is called the ordered entry selection rule). An explicit expression for the traffic handled by the various servers in a

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

    Directory of Open Access Journals (Sweden)

    Sung J. Kim

    2013-01-01

    Full Text Available We consider the discrete-time GeoX/G/1 queue under N-policy with single and multiple vacations. In this queueing system, the server takes multiple vacations and a single vacation whenever the system becomes empty and begins to serve customers only if the queue length is at least a predetermined threshold value N. Using the well-known property of stochastic decomposition, we derive the stationary queue-length distributions for both vacation models in a simple and unified manner. In addition, we derive their busy as well as idle-period distributions. Some classical vacation models are considered as special cases.

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

    African Journals Online (AJOL)

    K Ramanath & P Lakshmi distributed service time. This paper is an extension of their work to the case where the service times are generally distributed. We obtain Markov regenerative stochastic Petri net (MRSPN) representations of the. M/G/1/N queueing systems with server vacations under a limited service discipline. For.

  8. Analysis of Markov-modulated infinite-server queues in the central-limit regime

    NARCIS (Netherlands)

    J.G. Blom (Joke); K. de Turck (Koen); M.R.H. Mandjes (Michel)

    2014-01-01

    textabstractThis paper focuses on an infinite-server queue modulated by an independently evolving finite-state Markovian background process, with transition rate matrix $Q\\equiv(q_{ij})_{i,j=1}^d$. {Both arrival rates and service rates are depending on the state of the background

  9. Analysis of Markov-modulated infinite-server queues in the central-limit regime

    NARCIS (Netherlands)

    J.G. Blom (Joke); K. de Turck (Koen); M.R.H. Mandjes (Michel)

    2014-01-01

    textabstractThis paper focuses on an infinite-server queue modulated by an independently evolving finite-state Markovian background process, with transition rate matrix $Q\\equiv(q_{ij})_{i,j=1}^d$. Both arrival rates and service rates are depending on the state of the background process. The

  10. Analysis of Markov-modulated infinite-server queues in the central-limit regime

    NARCIS (Netherlands)

    J.G. Blom (Joke); K. de Turck (Koen); M.R.H. Mandjes (Michel)

    2015-01-01

    textabstractThis paper focuses on an infinite-server queue modulated by an independently evolving finite-state Markovian background process, with transition rate matrix $Q\\equiv(q_{ij})_{i,j=1}^d$. {Both arrival rates and service rates are depending on the state of the background

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

    Directory of Open Access Journals (Sweden)

    U. C. Gupta

    2015-01-01

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

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

    Science.gov (United States)

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

    2017-11-01

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

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

    International Nuclear Information System (INIS)

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

    1982-01-01

    In the paper the problem of the discretized cluster length probability determination based on the scanning in the track chambers is considered. This problem is solved in the frame of the queueing system with infinitely many servers as a discretized busy period probability determination of this system. The precise formulae of a probability are given and it is proved that those probabilities converge weakly to the probability distribution of the nondiscretized cluster when the discretization steps are diminished

  14. Batch arrival discrete time queue with gated vacation system ...

    African Journals Online (AJOL)

    A class of single server vacation queues, which have batch arrivals and single server, is considered in discrete time. Here the server goes on vacation of random length as soon as the system becomes empty. On return from vacation, if he finds any customers waiting in the queue, the server starts serving the customers one ...

  15. Analysis of Multiserver Queueing System with Opportunistic Occupation and Reservation of Servers

    Directory of Open Access Journals (Sweden)

    Bin Sun

    2014-01-01

    Full Text Available We consider a multiserver queueing system with two input flows. Type-1 customers have preemptive priority and are lost during arrival only if all servers are occupied by type-1 customers. If all servers are occupied, but some provide service to type-2 customers, service of type-2 customer is terminated and type-1 customer occupies the server. If the number of busy servers is less than the threshold M during type-2 customer arrival epoch, this customer is accepted. Otherwise, it is lost or becomes a retrial customer. It will retry to obtain service. Type-2 customer whose service is terminated is lost or moves to the pool of retrial customers. The service time is exponentially distributed with the rate dependent on the customer’s type. Such queueing system is suitable for modeling cognitive radio. Type-1 customers are interpreted as requests generated by primary users. Type-2 customers are generated by secondary or cognitive users. The problem of optimal choice of the threshold M is the subject of this paper. Behavior of the system is described by the multidimensional Markov chain. Its generator, ergodicity condition, and stationary distribution are given. The system performance measures are obtained. The numerical results show the effectiveness of considered admission control.

  16. Transient solution of an M/M/1 vacation queue with a waiting server and impatient customers

    Directory of Open Access Journals (Sweden)

    Sherif I. Ammar

    2017-07-01

    Full Text Available Recently, Ammar [1] has discussed the transient behavior of a multiple vacations queue with impatient customers. In this paper, a similar technique is used to derive a new elegant explicit solution for an M/M/1 vacation queue with impatient customers and a waiting server, where the server is allowed to take a vacation whenever the system is empty after waiting for a random period of time. If the server does not return from the vacation before the expiry of the customer impatience time, the customer abandons the system forever. Moreover, the formulas of mean and variance expressed in terms of the obtained possibilities for this model.

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

    Directory of Open Access Journals (Sweden)

    S. Chakravarthy

    1994-01-01

    Full Text Available In this paper we consider a finite capacity queuing system in which arrivals are governed by a Markovian arrival process. The system is attended by two exponential servers, who offer services in groups of varying sizes. The service rates may depend on the number of customers in service. Using Markov theory, we study this finite capacity queuing model in detail by obtaining numerically stable expressions for (a the steady-state queue length densities at arrivals and at arbitrary time points; (b the Laplace-Stieltjes transform of the stationary waiting time distribution of an admitted customer at points of arrivals. The stationary waiting time distribution is shown to be of phase type when the interarrival times are of phase type. Efficient algorithmic procedures for computing the steady-state queue length densities and other system performance measures are discussed. A conjecture on the nature of the mean waiting time is proposed. Some illustrative numerical examples are presented.

  18. ANALYSIS OF MULTI-SERVER QUEUEING SYSTEM WITH PREEMPTIVE PRIORITY AND REPEATED CALLS

    Directory of Open Access Journals (Sweden)

    S. A. Dudin

    2015-01-01

    Full Text Available Multi-server retrial queueing system with no buffer and two types of customers is analyzed as the model of cognitive radio system. Customers of type 1 have a preemptive priority. Customers of both types arrive according to Markovian Arrival Processes. Service times have exponential distribution with parameter depending on the customer type. Type 2 customers are admitted for service only if the number of busy servers is less than the predefined threshold. The rejected type 2 customers retry for the service. Existence condition of the stationary mode of system operation is derived. Formulas for computing key performance measures of the system are presented.

  19. Analysis on preemptive priority retrial queue with two types of customers, balking, optional re-service, single vacation and service interruption

    Science.gov (United States)

    Yuvarani, S.; Saravanarajan, M. C.

    2017-11-01

    This paper concerned with performance analysis of single server preemptive priority retrial queue with a single vacation where two types of customers are considered and they are called priority customers and ordinary customers. The ordinary customers arrive in batch into the system. The priority customers do not form any queue. After the completion of regular service, the customers may demand re-service for the previous service without joining the orbit or may leave the system. As soon as the system is empty, the server goes for vacation and the regular busy server can be subjected to breakdown. By using the supplementary variable technique, we obtain the steady-state probability generating functions for the system/orbit size. Some important system performance measures and the stochastic decomposition are discussed. Finally, numerical examples are presented to visualize the effect of parameters on system performance measures.

  20. Efficient estimation of overflow probabilities in queues with breakdowns

    NARCIS (Netherlands)

    Kroese, Dirk; Nicola, V.F.

    1999-01-01

    Efficient importance sampling methods are proposed for the simulation of a single server queue with server breakdowns. The server is assumed to alternate between the operational and failure states according to a continuous time Markov chain. Both, continuous (fluid flow) and discrete (single

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

    African Journals Online (AJOL)

    The theory of non-Markovian stochastic Petri nets is employed in this paper to derive an alternative method for studying the steady state behaviour of the M/G/1 vacation queueing system with a limited service discipline. Three types of vacation schemes are considered, and sytems with both a finite population and those with ...

  2. A group arrival retrial G - queue with multi optional stages of service, orbital search and server breakdown

    Science.gov (United States)

    Radha, J.; Indhira, K.; Chandrasekaran, V. M.

    2017-11-01

    A group arrival feedback retrial queue with k optional stages of service and orbital search policy is studied. Any arriving group of customer finds the server free, one from the group enters into the first stage of service and the rest of the group join into the orbit. After completion of the i th stage of service, the customer under service may have the option to choose (i+1)th stage of service with θi probability, with pI probability may join into orbit as feedback customer or may leave the system with {q}i=≤ft\\{\\begin{array}{l}1-{p}i-{θ }i,i=1,2,\\cdots k-1\\ 1-{p}i,i=k\\end{array}\\right\\} probability. Busy server may get to breakdown due to the arrival of negative customers and the service channel will fail for a short interval of time. At the completion of service or repair, the server searches for the customer in the orbit (if any) with probability α or remains idle with probability 1-α. By using the supplementary variable method, steady state probability generating function for system size, some system performance measures are discussed.

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

    DEFF Research Database (Denmark)

    Platz, Trine Tornøe; Østerdal, Lars Peter Raahave

    2017-01-01

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

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

    Directory of Open Access Journals (Sweden)

    K Ramanath

    2006-12-01

    Full Text Available The theory of non-Markovian stochastic Petri nets is employed in this paper to derive an alternative method for studying the steady state behaviour of the M/G/1 vacation queueing system with a limited service discipline. Three types of vacation schemes are considered, and sytems with both a finite population and those with an infinite population (but finite capacity are considered. Simple numerical examples are also provided to illustrate the functionality of the methods and some useful performance measures for the system are obtained.

  5. Analysis and Adaptive Control of a Discrete-Time Single-Server Network with Random Routing

    National Research Council Canada - National Science Library

    Makowski, Armand M; Shwartz, Adam

    1989-01-01

    .... Customers arrive in i.i.d batches and are served according to a server allocation policy. Upon completing service, customers either leave the system or are routed instantaneously to another queue according to some random mechnism...

  6. Analysis and Adaptive Control of a Discrete-Time Single-Server Network with Random Routing

    National Research Council Canada - National Science Library

    Makowski, Armand M; Shwartz, Adam

    1989-01-01

    .... Customers arrive in i.i,d batches and are served according to a server allocation policy. Upon completing service, customers either leave the system or are routed instantaneously to another queue according to some random mechanism...

  7. Single Sign-on Authentication server (part of CLARIN infrastructure)

    NARCIS (Netherlands)

    de Jong, H.A.; Maas, M.

    2013-01-01

    The Huygens Single Sign-on server allows federated logins (authentication) via SURFconext affiliates thus facilitating all connected (academic / research) institutes to use online Huygens ING software services.

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

    Directory of Open Access Journals (Sweden)

    Woźniak Marcin

    2014-12-01

    Full Text Available In this paper, application of an evolutionary strategy to positioning a GI/M/1/N-type finite-buffer queueing system with exhaustive service and a single vacation policy is presented. The examined object is modeled by a conditional joint transform of the first busy period, the first idle time and the number of packets completely served during the first busy period. A mathematical model is defined recursively by means of input distributions. In the paper, an analytical study and numerical experiments are presented. A cost optimization problem is solved using an evolutionary strategy for a class of queueing systems described by exponential and Erlang distributions.

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

    Directory of Open Access Journals (Sweden)

    David C. R. Muh

    1993-01-01

    Full Text Available The author studies the queueing process in a single-server, bulk arrival and batch service queueing system with a compound Poisson input, bilevel service delay discipline, start-up time, and a fixed accumulation level with control operating policy. It is assumed that when the queue length falls below a predefined level r(≥1, the system, with server capacity R, immediately stops service until the queue length reaches or exceeds the second predefined accumulation level N(≥r. Two cases, with N≤R and N≥R, are studied.

  10. discouraged by queue length

    Directory of Open Access Journals (Sweden)

    P. R. Parthasarathy

    2001-01-01

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

  11. 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.

  12. Queues with waiting time dependent service

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  13. A polling model with an autonomous server

    NARCIS (Netherlands)

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

    2009-01-01

    This paper considers polling systems with an autonomous server that remain at a queue for an exponential amount of time before moving to a next queue incurring a generally distributed switch-over time. The server remains at a queue until the exponential visit time expires, also when the queue

  14. Bulk input queues with quorum and multiple vacations

    Directory of Open Access Journals (Sweden)

    Dshalalow Jewgeni H.

    1996-01-01

    Full Text Available The authors study a single-server queueing system with bulk arrivals and batch service in accordance to the general quorum discipline: a batch taken for service is not less than r and not greater than R ( ≥ r . The server takes vacations each time the queue level falls below r ( ≥ 1 in accordance with the multiple vacation discipline. The input to the system is assumed to be a compound Poisson process. The analysis of the system is based on the theory of first excess processes developed by the first author. A preliminary analysis of such processes enabled the authors to obtain all major characteristics for the queueing process in an analytically tractable form. Some examples and applications are given.

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

    Directory of Open Access Journals (Sweden)

    Bart Steyaert

    2011-01-01

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

  16. 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.

  17. 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.

  18. The optimal look-ahead policy for admission to a single server system

    NARCIS (Netherlands)

    Nawijn, W.M.

    1985-01-01

    This paper considers a service system with a single server, finite waiting room, and a renewal arrival process. Customers who arrive while the server is busy are lost. Upon completing service, the server chooses between two actions: either he immediately starts a new service, provided a customer is

  19. Look-ahead policies for admission to a single server loss system

    NARCIS (Netherlands)

    Nawijn, W.M.

    1990-01-01

    Consider a single server loss system in which the server, being idle, may reject or accept an arriving customer for service depending on the state at the arrival epoch. It is assumed that at every arrival epoch the server knows the service time of the arriving customer, the arrival time of the next

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

    Directory of Open Access Journals (Sweden)

    F. S. Q. Alves

    2011-01-01

    Full Text Available In many real-life queueing systems, the servers are often heterogeneous, namely they work at different rates. This paper provides a simple method to compute tight upper bounds on two important performance measures of single-class heterogeneous multi-server Markovian queueing systems, namely the average number in queue and the average waiting time in queue. This method is based on an expansion of the state space that is followed by an approximate reduction of the state space, only considering the most probable states. In most cases tested, we were able to approximate the actual behavior of the system with smaller errors than those obtained from traditional homogeneous multiserver Markovian queues, as shown by GPSS simulations. In addition, we have correlated the quality of the approximation with the degree of heterogeneity of the system, which was evaluated using its Gini index. Finally, we have shown that the bounds are robust and still useful, even considering quite different allocation strategies. A large number of simulation results show the accuracy of the proposed method that is better than that of classical homogeneous multiserver Markovian formulae in many situations.

  1. On the Two-Moment Approximation of the Discrete-Time GI/G/1 Queue with a Single Vacation

    Directory of Open Access Journals (Sweden)

    Doo Ho Lee

    2016-01-01

    Full Text Available We consider a discrete-time GI/G/1 queue in which the server takes exactly one vacation each time the system becomes empty. The interarrival times of arriving customers, the service times, and the vacation times are all generic discrete random variables. Under our study, we derive an exact transform-free expression for the stationary system size distribution through the modified supplementary variable technique. Utilizing obtained results, we introduce a simple two-moment approximation for the system size distribution. From this, approximations for the mean system size along with the system size distribution could be obtained. Finally, some numerical examples are given to validate the proposed approximation method.

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

    NARCIS (Netherlands)

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

    2007-01-01

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

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

    NARCIS (Netherlands)

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

    2009-01-01

    We discuss a single-server multi-station alternating queue where the preparation times and the service times are auto- and cross-correlated. We examine two cases. In the first case, preparation and service times depend on a common discrete time Markov chain. In the second case, we assume that the

  4. Vacation queueing models theory and applications

    CERN Document Server

    Tian, Naishuo

    2006-01-01

    A classical queueing model consists of three parts - arrival process, service process, and queue discipline. However, a vacation queueing model has an additional part - the vacation process which is governed by a vacation policy - that can be characterized by three aspects: 1) vacation start-up rule; 2) vacation termination rule, and 3) vacation duration distribution. Hence, vacation queueing models are an extension of classical queueing theory. Vacation Queueing Models: Theory and Applications discusses systematically and in detail the many variations of vacation policy. By allowing servers to take vacations makes the queueing models more realistic and flexible in studying real-world waiting line systems. Integrated in the book's discussion are a variety of typical vacation model applications that include call centers with multi-task employees, customized manufacturing, telecommunication networks, maintenance activities, etc. Finally, contents are presented in a "theorem and proof" format and it is invaluabl...

  5. Cost sharing of cooperating queues in a Jackson network

    NARCIS (Netherlands)

    Timmer, Judith B.; Scheinhardt, Willem R.W.

    2012-01-01

    We consider networks of queues in which the independent operators of individual queues may cooperate to reduce the amount of waiting. More specifically, we focus on Jackson networks in which the total capacity of the servers can be redistributed over all queues in any desired way. If we associate a

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  7. Optimal control of two queues in series

    International Nuclear Information System (INIS)

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

    1994-08-01

    In this paper we give a fairly complete survey of the available results on the control of arrival and service rates for both single queue and networks of queues. We also study two M/M/1 queues in series. At the first queue, the arrival and the service rates are chosen in pair from a finite set whenever the queue lengths at both queues change. Each choice has a switching cost depending on the chosen rates and the queue lengths. At the second queue, the arrival and the service rates are fixed. Our objective is to find a policy for dynamically choosing rates, based on the current rates and queues lengths that minimizes the expected total discounted cost over a finite horizon, numerical results are given. (author). 8 refs, 1 fig

  8. Markov-modulated M/G/1-type queue in heavy traffic and its application to time-sharing disciplines

    NARCIS (Netherlands)

    H. Thorsdottir (Halldora); I.M. Verloop (Maaike)

    2016-01-01

    textabstractThis paper deals with a single-server queue with modulated arrivals, service requirements and service capacity. In our first result, we derive the mean of the total workload assuming generally distributed service requirements and any service discipline which does not depend on the

  9. A Capacity Supply Model for Virtualized Servers

    Directory of Open Access Journals (Sweden)

    Alexander PINNOW

    2009-01-01

    Full Text Available This paper deals with determining the capacity supply for virtualized servers. First, a server is modeled as a queue based on a Markov chain. Then, the effect of server virtualization on the capacity supply will be analyzed with the distribution function of the server load.

  10. Effect of information, uncertainty and parameter variability on profits in a queue with various pricing strategies

    Science.gov (United States)

    Sun, Wei; Li, Shiyong

    2014-08-01

    This paper presents an unobservable single-server queueing system with three types of uncertainty, where the service rate, or waiting cost or service quality is random variable that may obtain n(n > 2) values. The information about the realised values of parameters is only known to the server. We are concerned about the server's behaviour: revealing or concealing the information to customers. The n-value assumption and the server's behaviour enable us to consider various pricing strategies. In this paper, we analyse the effect of information and uncertainty on profits and make comparisons between the profits under different pricing strategies. Moreover, as for parameter variability reflected by the number of each parameter's possible choices n, we observe the effect of variable n on all types of profits and find that revealing the parameter information can much more benefit the server with the increase of n.

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

    Directory of Open Access Journals (Sweden)

    Veena Goswami

    2014-01-01

    Full Text Available This paper presents an analysis of balking and reneging in finite-buffer discrete-time single server queue with single and multiple working vacations. An arriving customer may balk with a probability or renege after joining according to a geometric distribution. The server works with different service rates rather than completely stopping the service during a vacation period. The service times during a busy period, vacation period, and vacation times are assumed to be geometrically distributed. We find the explicit expressions for the stationary state probabilities. Various system performance measures and a cost model to determine the optimal service rates are presented. Moreover, some queueing models presented in the literature are derived as special cases of our model. Finally, the influence of various parameters on the performance characteristics is shown numerically.

  12. Applied discrete-time queues

    CERN Document Server

    Alfa, Attahiru S

    2016-01-01

    This book introduces the theoretical fundamentals for modeling queues in discrete-time, and the basic procedures for developing queuing models in discrete-time. There is a focus on applications in modern telecommunication systems. It presents how most queueing models in discrete-time can be set up as discrete-time Markov chains. Techniques such as matrix-analytic methods (MAM) that can used to analyze the resulting Markov chains are included. This book covers single node systems, tandem system and queueing networks. It shows how queues with time-varying parameters can be analyzed, and illustrates numerical issues associated with computations for the discrete-time queueing systems. Optimal control of queues is also covered. Applied Discrete-Time Queues targets researchers, advanced-level students and analysts in the field of telecommunication networks. It is suitable as a reference book and can also be used as a secondary text book in computer engineering and computer science. Examples and exercises are includ...

  13. On a bulk queueing system with impatient customers

    Directory of Open Access Journals (Sweden)

    Tadj Lotfi

    1997-01-01

    Full Text Available We consider a bulk arrival, bulk service queueing system. Customers are served in batches of r units if the queue length is not less than r . Otherwise, the server delays the service until the number of units in the queue reaches or exceeds level r . We assume that unserved customers may get impatient and leave the system. An ergodicity condition and steady-state probabilities are derived. Various system characteristics are also computed.

  14. On a bulk queueing system with impatient customers

    Directory of Open Access Journals (Sweden)

    Lotfi Tadj

    1998-01-01

    Full Text Available We consider a bulk arrival, bulk service queueing system. Customers are served in batches of r units if the queue length is not less than r. Otherwise, the server delays the service until the number of units in the queue reaches or exceeds level r. We assume that unserved customers may get impatient and leave the system. An ergodicity condition and steady-state probabilities are derived. Various system characteristics are also computed.

  15. Analysis of Fuzzy Queue Characteristics by Flexible Alpha-cuts Method

    Directory of Open Access Journals (Sweden)

    J. P. Mukeba K.

    2017-03-01

    Full Text Available This article is a contribution to papers applying two kinds of fuzzy arithmetics to analyze fuzzy queues characteristics, namely, fuzzy arithmetic based on Zadeh's extension principle and fuzzy arithmetic based on alpha-cuts and intervals arithmetic. The two arithmetics being compatible, the paper shows that without reference to arithmetic based on Zadeh's extension principle, fuzzy queues characteristics can be analyzed normally by an other technique called flexible $\\alpha-cuts$ method following which all calculations are based only on alpha-cuts approach. To accomplish this task, the paper brings out all mathematical optimization programs contained in intervals arithmetic, which is one of ineluctable tools of $\\alpha-cuts$ approach, and shows how these programs are solved progressively. To illustrate this approach, the expected customer waiting time and the expected customers number in a single server fuzzy retrial queue are computed at steady state through an example in the next to last section.

  16. Quasi-stationary analysis for queues with temporary overload

    NARCIS (Netherlands)

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

    2010-01-01

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

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

    National Research Council Canada - National Science Library

    Chapin, Patrick

    2004-01-01

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

  18. Approximate Analysis of an Unreliable M/M/2 Retrial Queue

    Science.gov (United States)

    2007-03-01

    retrial queue studied most recently was by Abramov in 2006 [1] in which customers arrive according to a general renewal process with m servers whose...retrial queues in which the phase-merging algorithm can be applied. 5-2 Bibliography 1. Abramov , V. M. (2006). Analysis of multiserver retrial queueing

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

    Directory of Open Access Journals (Sweden)

    S. R. Chakravarthy

    1997-01-01

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

  20. Publishing E-RDF linked data for many agents by single third-party server

    DEFF Research Database (Denmark)

    Wang, Dongsheng; Zhang, Yongyuan; Wang, Zhengjun

    2017-01-01

    do not have the ability or do not want to make an additional effort to publish linked data. Thus, for agents who are willing to open part of their data but do not want to make an effort, the task can be undertaken by a professional third-party server (together with professional experts......) that publishes linked data for these agents. Consequently, when a single third-party server is on behalf of multiple agents, it is also responsible to organize these multiple-source URIs (data) in a systematic way to make them referable, satisfying the 4-star data principles, as well as protect the confidential...

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

    Science.gov (United States)

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

    2017-06-01

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

  2. Queueing networks a fundamental approach

    CERN Document Server

    Dijk, Nico

    2011-01-01

    This handbook aims to highlight fundamental, methodological and computational aspects of networks of queues to provide insights and to unify results that can be applied in a more general manner.  The handbook is organized into five parts: Part 1 considers exact analytical results such as of product form type. Topics include characterization of product forms by physical balance concepts and simple traffic flow equations, classes of service and queue disciplines that allow a product form, a unified description of product forms for discrete time queueing networks, insights for insensitivity, and aggregation and decomposition results that allow subnetworks to be aggregated into single nodes to reduce computational burden. Part 2 looks at monotonicity and comparison results such as for computational simplification by either of two approaches: stochastic monotonicity and ordering results based on the ordering of the proces generators, and comparison results and explicit error bounds based on an underlying Markov r...

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

    Directory of Open Access Journals (Sweden)

    Charles Knessl

    2011-01-01

    Full Text Available We consider two coupled queues with a generalized processor sharing service discipline. The second queue has a much smaller Poisson arrival rate than the first queue, while the customer service times are of comparable magnitude. The processor sharing server devotes most of its resources to the first queue, except when it is empty. The fraction of resources devoted to the second queue is small, of the same order as the ratio of the arrival rates. We assume that the primary queue is heavily loaded and that the secondary queue is critically loaded. If we let the small arrival rate to the secondary queue be O(ε, where 0≤ε≪1, then in this asymptotic limit the number of customers in the first queue will be large, of order O(ε-1, while that in the second queue will be somewhat smaller, of order O(ε-1/2. We obtain a two-dimensional diffusion approximation for this model and explicitly solve for the joint steady state probability distribution of the numbers of customers in the two queues. This work complements that in (Morrison, 2010, which the second queue was assumed to be heavily or lightly loaded, leading to mean queue lengths that were O(ε-1 or O(1, respectively.

  4. Approximate analysis of non-stationary loss queues and networks of loss queues with general service time distributions

    OpenAIRE

    Izady, N; Worthington, D J

    2011-01-01

    A Fixed Point Approximation (FPA) method has recently been suggested for non-stationary analysis of loss queues and networks of loss queues with Exponential service times. Deriving exact equations relating time-dependent mean numbers of busy servers to blocking probabilities, we generalize the FPA method to loss systems with general service time distributions. These equations are combined with associated formulae for stationary analysis of loss systems in steady state through a carried load t...

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

    Science.gov (United States)

    Bent, John M.; Faibish, Sorin

    2015-08-18

    Interactive requests are processed from users of log-in nodes. A metadata server node is provided for use in a file system shared by one or more interactive nodes and one or more batch nodes. The interactive nodes comprise interactive clients to execute interactive tasks and the batch nodes execute batch jobs for one or more batch clients. The metadata server node comprises a virtual machine monitor; an interactive client proxy to store metadata requests from the interactive clients in an interactive client queue; a batch client proxy to store metadata requests from the batch clients in a batch client queue; and a metadata server to store the metadata requests from the interactive client queue and the batch client queue in a metadata queue based on an allocation of resources by the virtual machine monitor. The metadata requests can be prioritized, for example, based on one or more of a predefined policy and predefined rules.

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

    International Nuclear Information System (INIS)

    Dvurecenskij, A.; Ososkov, G.A.

    1982-01-01

    The problem of determining the distribution of the busy period, i. e., of the time when at least one customer is served, of the discretized queueing system with infinitely many servers is investigated. Moreover, the idle period and the cycle of a queue are studied. The recurrent formulae are determined and in particular case of a queue with the geometric input the simpler recurrent formulae are given. Those problems arise in the discrete blob length determination in track chambers in high energy physics

  7. Analysis of a generalized shortest queue system by flexible bound models

    NARCIS (Netherlands)

    van Houtum, G.J.; Klein Haneveld, W.K.; Vrieze, O.J.; Kallenberg, L.C.M.

    1997-01-01

    Motivated by a practical situation for the production/assembly of printed circuit boards, we study a generalized shortest queue system. This system consists of parallel servers, which all have their own queue. The system serves several types of jobs, which arrive according to Poisson processes.

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

    Directory of Open Access Journals (Sweden)

    Yan Ma

    2015-01-01

    Full Text Available This paper studies the equilibrium behavior of customers and optimal pricing strategies of servers in a Geo/Geo/1 queueing system. Two common pricing mechanisms are considered. The first one is called ex-post payment (EPP scheme where the server collects tolls proportional to queue times, and the second one is called ex-ante payment (EAP scheme where the server charges a flat fee for the total service. The server sets the toll price to maximize its own profit. It is found that, under a customer’s choice equilibrium, the two toll mechanisms are equivalent from the economic point of view. Finally, we present several numerical experiments to investigate the effects of system parameters on the equilibrium customer joining rate and servers’ profits.

  9. Fast meldable priority queues

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting

    1995-01-01

    We present priority queues that support the operations Find-Min, Insert, MakeQueue and Meld in worst case time O(1) and Delete and DeleteMin in worst case time O(log n). They can be implemented on the pointer machine and require linear space. The time bounds are optimal for all implementations...... where Meld takes worst case time o(n). To our knowledge this is the first priority queue implementation that supports Meld in worst case constant time and DeleteMin in logarithmic time....

  10. Queueing Theory With Reneging

    Science.gov (United States)

    2005-09-01

    Strategic Logistics Doc Data Sheet Intelligence and Security Group DGSTA Defence Intelligence Organisation 1 Printed Manager , Information Centre......particularly in situations where queueing theory forms only a part of the model of a defence system. RELEASE LIMITATION Approved for

  11. Fundamentals of queueing theory

    CERN Document Server

    Gross, Donald; Thompson, James M; Harris, Carl M

    2013-01-01

    Praise for the Third Edition ""This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented.""-IIE Transactions on Operations Engineering Thoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than pre

  12. Analysis of Queue-Length Dependent Vacations and P-Limited Service in BMAP/G/1/N Systems: Stationary Distributions and Optimal Control

    Directory of Open Access Journals (Sweden)

    A. D. Banik

    2013-01-01

    Full Text Available We consider a finite-buffer single server queueing system with queue-length dependent vacations where arrivals occur according to a batch Markovian arrival process (BMAP. The service discipline is P-limited service, also called E-limited with limit variation (ELV where the server serves until either the system is emptied or a randomly chosen limit of L customers has been served. Depending on the number of customers present in the system, the server will monitor his vacation times. Queue-length distributions at various epochs such as before, arrival, arbitrary and after, departure have been obtained. Several other service disciplines like Bernoulli scheduling, nonexhaustive service, and E-limited service can be treated as special cases of the P-limited service. Finally, the total expected cost function per unit time is considered to determine locally optimal values N* of N or a maximum limit L^* of L^ as the number of customers served during a service period at a minimum cost.

  13. A queueing theory description of fat-tailed price returns in imperfect financial markets

    Science.gov (United States)

    Lamba, H.

    2010-09-01

    In a financial market, for agents with long investment horizons or at times of severe market stress, it is often changes in the asset price that act as the trigger for transactions or shifts in investment position. This suggests the use of price thresholds to simulate agent behavior over much longer timescales than are currently used in models of order-books. We show that many phenomena, routinely ignored in efficient market theory, can be systematically introduced into an otherwise efficient market, resulting in models that robustly replicate the most important stylized facts. We then demonstrate a close link between such threshold models and queueing theory, with large price changes corresponding to the busy periods of a single-server queue. The distribution of the busy periods is known to have excess kurtosis and non-exponential decay under various assumptions on the queue parameters. Such an approach may prove useful in the development of mathematical models for rapid deleveraging and panics in financial markets, and the stress-testing of financial institutions.

  14. CPU Server

    CERN Multimedia

    The CERN computer centre has hundreds of racks like these. They are over a million times more powerful than our first computer in the 1960's. This tray is a 'dual-core' server. This means it effectively has two CPUs in it (eg. two of your home computers minimised to fit into a single box). Also note the copper cooling fins, to help dissipate the heat.

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

    Directory of Open Access Journals (Sweden)

    Charan Jeet Singh

    2016-03-01

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

  16. Interacting queues in heavy traffic

    NARCIS (Netherlands)

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

    2010-01-01

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

  17. The symmetric longest queue system

    NARCIS (Netherlands)

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

    1997-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Jewgeni H. Dshalalow

    1996-01-01

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

  19. Game server

    OpenAIRE

    Čermák, Miroslav

    2007-01-01

    Main goal of this work is to create new web application "game server" in PHP programming language. Server consists of Main module and extension modules: Chess module and Fun module. It also enables user to share pictures, videos and funny texts, chat and play chess. Part of the application is system of user roles that is used to manage and apply rights for common operations and administrative interface to manage server users and modules. Extension of server functionality can be done by adding...

  20. Effect of queue discipline on the performance of a queueing system ...

    African Journals Online (AJOL)

    LIFO) and service in random order (SIRO) on some measures of performance of a single sever queue are examined. The measures of performance are average waiting time and queuing time. The comparison of the systems were carried out by ...

  1. Analysis of an MAP/PH/1 Queue with Flexible Group Service

    Directory of Open Access Journals (Sweden)

    Brugno Arianna

    2017-03-01

    Full Text Available A novel customer batch service discipline for a single server queue is introduced and analyzed. Service to customers is offered in batches of a certain size. If the number of customers in the system at the service completion moment is less than this size, the server does not start the next service until the number of customers in the system reaches this size or a random limitation of the idle time of the server expires, whichever occurs first. Customers arrive according to a Markovian arrival process. An individual customer’s service time has a phase-type distribution. The service time of a batch is defined as the maximum of the individual service times of the customers which form the batch. The dynamics of such a system are described by a multi-dimensional Markov chain. An ergodicity condition for this Markov chain is derived, a stationary probability distribution of the states is computed, and formulas for the main performance measures of the system are provided. The Laplace–Stieltjes transform of the waiting time is obtained. Results are numerically illustrated.

  2. Priority-queue framework: Programs

    DEFF Research Database (Denmark)

    Katajainen, Jyrki

    2009-01-01

    This is an electronic appendix to the article "Generic-programming framework for benchmarking weak queues and its relatives". The report contains the programs related to our priority-queue framework. Look at the CPH STL reports 2009-3 and 2009-4 to see examples of other component frameworks....

  3. Lévy-driven queues

    NARCIS (Netherlands)

    Dębicki, K.; Mandjes, M.

    2012-01-01

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

  4. A Survey on Priority Queues

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting

    2013-01-01

    Back in 1964 Williams introduced the binary heap as a basic priority queue data structure supporting the operations Insert and ExtractMin in logarithmic time. Since then numerous papers have been published on priority queues. This paper tries to list some of the directions research on priority...

  5. Optimal purely functional priority queues

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Okasaki, Chris

    1996-01-01

    Brodal's data structure to a purely functional setting. In doing so, we both simplify the data structure and clarify its relationship to the binomial queues of Vuillemin, which support all four operations in O(log n) time. Specifically, we derive our implementation from binomial queues in three steps...

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

    NARCIS (Netherlands)

    Cheung, S.-K.; Berg, H. van den; Boucherie, R.J.

    2005-01-01

    We obtain a decomposition result for the steady state queue length distribution in egalitarian processor-sharing (PS) models. In particular, for multi-class egalitarian PS queues, we show that the marginal queue length distribution for each class equals the queue length distribution of an equivalent

  7. The busy period of order n in the GI/D/infinity queue

    International Nuclear Information System (INIS)

    Dvurecenskij, A.

    1982-01-01

    The problem of determination of the distribution function, integral equation and all moments of the busy period of order n, that is, the period when at least n servers are busy from infinitely many servers of the GI/D/infinity queueing system are investigated. The idle period of order n, i. e., the period between two neighbouring busy periods of order n is also studied. Those problems arise in the blob length determination in track chambers in high energy physics

  8. A Report on Stochastic Fairness Queueing (SFQ) Experiments

    Science.gov (United States)

    Denny, Barbara A.

    1993-01-01

    SRI International (SRI) has developed an improved queueing algorithm, known as Stochastic Fairness Queueing (SFQ), for best-effort traffic (i.e., traffic that does not require any guaranteed service). SFQ is a probablistic variant of strict fair queueing where instead of a single queue being allocated per flow, a fixed number of queues are used and a hash function maps the IP source and destination to a particular queue. A seed to the hash function is also perturbed occasionally to help distribute the flows amongst different queues when more than one flow maps to the same queue during the lifetime of the flow. SFQ provides 'fair' access by trying to ensure that each flow from source to destination host obtains equal access to the available bandwidth. This report covers a series of experiments performed on DARTnet evaluating the behavior and performance of SFQ against a FIFO queueing discipline. These experiments were designed to show SFQ's advantages and performance, and include tests demonstrating: Fair utilization of available resources; Starvation prevention; Graceful degradation under overload conditions; and Resource usage. In general, the experiments do show that SFQ is better than FIFO queueing at allocating bandwidth equally among a set of flows. SFQ also prevents a stream from dominating the available bandwidth, which seems to be a tendency with FIFO queueing (i.e., if a flow demands more than its share of the available bandwidth, with FIFO queueing that stream receives a disproportionate amount when compared to flows demanding less than their share). Furthermore, SFQ seems to reward 'nice' users of the network by providing a lower variance in delay and more throughput when their resource demand is less than their available share. Both SFQ and FIFO queueing seem to degrade fairly well as the network becomes saturated and to recover well as the network becomes less congested. Not unexpectedly, FIFO queueing is a little more efficient than SFQ-the delays are

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  10. State dependent arrival in bulk retrial queueing system with immediate Bernoulli feedback, multiple vacations and threshold

    Science.gov (United States)

    Niranjan, S. P.; Chandrasekaran, V. M.; Indhira, K.

    2017-11-01

    The objective of this paper is to analyse state dependent arrival in bulk retrial queueing system with immediate Bernoulli feedback, multiple vacations, threshold and constant retrial policy. Primary customers are arriving into the system in bulk with different arrival rates λ a and λ b . If arriving customers find the server is busy then the entire batch will join to orbit. Customer from orbit request service one by one with constant retrial rate γ. On the other hand if an arrival of customers finds the server is idle then customers will be served in batches according to general bulk service rule. After service completion, customers may request service again with probability δ as feedback or leave from the system with probability 1 ‑ δ. In the service completion epoch, if the orbit size is zero then the server leaves for multiple vacations. The server continues the vacation until the orbit size reaches the value ‘N’ (N > b). At the vacation completion, if the orbit size is ‘N’ then the server becomes ready to provide service for customers from the main pool or from the orbit. For the designed queueing model, probability generating function of the queue size at an arbitrary time will be obtained by using supplementary variable technique. Various performance measures will be derived with suitable numerical illustrations.

  11. Multi stage unreliable retrial Queueing system with Bernoulli vacation

    Science.gov (United States)

    Radha, J.; Indhira, K.; Chandrasekaran, V. M.

    2017-11-01

    In this work we considered the Bernoulli vacation in group arrival retrial queues with unreliable server. Here, a server providing service in k stages. Any arriving group of units finds the server free, one from the group entering the first stage of service and the rest are joining into the orbit. After completion of the i th, (i=1,2,…k) stage of service, the customer may go to (i+1)th stage with probability θi , or leave the system with probability qi = 1 – θi , (i = 1,2,…k – 1) and qi = 1, (i = k). The server may enjoy vacation (orbit is empty or not) with probability v after finishing the service or continuing the service with probability 1-v. After finishing the vacation, the server search for the customer in the orbit with probability θ or remains idle for new arrival with probability 1-θ. We analyzed the system using the method of supplementary variable.

  12. Random queues and risk averse users

    DEFF Research Database (Denmark)

    de Palma, André; Fosgerau, Mogens

    2013-01-01

    We analyze Nash equilibrium in time of use of a congested facility. Users are risk averse with general concave utility. Queues are subject to varying degrees of random sorting, ranging from strict queue priority to a completely random queue. We define the key “no residual queue” property, which...

  13. A course on queueing models

    CERN Document Server

    Jain, Joti Lal; Böhm, Walter

    2006-01-01

    The application of engineering principles in divergent fields such as management science and communications as well as the advancement of several approaches in theory and computation have led to growing interest in queueing models, creating the need for a comprehensive text. Emphasizing Markovian structures and the techniques that occur in different models, A Course on Queueing Models discusses recent developments in the field, different methodological tools - some of which are not available elsewhere - and computational techniques.While most books essentially address the classical methods of

  14. Probability, statistics, and queueing theory

    CERN Document Server

    Allen, Arnold O

    1990-01-01

    This is a textbook on applied probability and statistics with computer science applications for students at the upper undergraduate level. It may also be used as a self study book for the practicing computer science professional. The successful first edition of this book proved extremely useful to students who need to use probability, statistics and queueing theory to solve problems in other fields, such as engineering, physics, operations research, and management science. The book has also been successfully used for courses in queueing theory for operations research students. This second edit

  15. 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.

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

    Directory of Open Access Journals (Sweden)

    Tamas Berczes

    2012-06-01

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

  17. An application of queueing theory to the design of channel requirements for special purpose communications satellites. Ph.D. Thesis

    Science.gov (United States)

    Hein, G. F.

    1974-01-01

    Special purpose satellites are very cost sensitive to the number of broadcast channels, usually will have Poisson arrivals, fairly low utilization (less than 35%), and a very high availability requirement. To solve the problem of determining the effects of limiting C the number of channels, the Poisson arrival, infinite server queueing model will be modified to describe the many server case. The model is predicated on the reproductive property of the Poisson distribution.

  18. Equilibrium Arrival Times to Queues

    DEFF Research Database (Denmark)

    Breinbjerg, Jesper; Østerdal, Lars Peter

    a symmetric (mixed) Nash equilibrium, and show that there is at most one symmetric equilibrium. We provide a numerical method to compute this equilibrium and demonstrate by a numerical example that the social effciency can be lower than the effciency induced by a similar queueing system that serves customers...

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

    Directory of Open Access Journals (Sweden)

    Robert B. Cooper

    1998-01-01

    Full Text Available The classical renewal-theory (waiting time, or inspection paradox states that the length of the renewal interval that covers a randomly-selected time epoch tends to be longer than an ordinary renewal interval. This paradox manifests itself in numerous interesting ways in queueing theory, a prime example being the celebrated Pollaczek-Khintchine formula for the mean waiting time in the M/G/1 queue. In this expository paper, we give intuitive arguments that “explain” why the renewal-theory paradox is ubiquitous in queueing theory, and why it sometimes produces anomalous results. In particular, we use these intuitive arguments to explain decomposition in vacation models, and to derive formulas that describe some recently-discovered counterintuitive results for polling models, such as the reduction of waiting times as a consequence of forcing the server to set up even when no work is waiting.

  20. Analysis of queues methods and applications

    CERN Document Server

    Gautam, Natarajan

    2012-01-01

    Introduction Analysis of Queues: Where, What, and How?Systems Analysis: Key ResultsQueueing Fundamentals and Notations Psychology in Queueing Reference Notes Exercises Exponential Interarrival and Service Times: Closed-Form Expressions Solving Balance Equations via Arc CutsSolving Balance Equations Using Generating Functions Solving Balance Equations Using Reversibility Reference Notes ExercisesExponential Interarrival and Service Times: Numerical Techniques and Approximations Multidimensional Birth and Death ChainsMultidimensional Markov Chains Finite-State Markov ChainsReference Notes Exerci

  1. Priority Queues Resilient to Memory Faults

    DEFF Research Database (Denmark)

    Jørgensen, Allan Grønlund; Moruz, Gabriel; Mølhave, Thomas

    2007-01-01

    In the faulty-memory RAM model, the content of memory cells can get corrupted at any time during the execution of an algorithm, and a constant number of uncorruptible registers are available. A resilient data structure in this model works correctly on the set of uncorrupted values. In this paper we...... introduce a resilient priority queue. The deletemin operation of a resilient priority queue returns either the minimum uncorrupted element or some corrupted element. Our resilient priority queue uses $O(n)$ space to store $n$ elements. Both insert and deletemin operations are performed in $O(\\log n...... queues storing only structural information in the uncorruptible registers between operations....

  2. Queues with Choice via Delay Differential Equations

    Science.gov (United States)

    Pender, Jamol; Rand, Richard H.; Wesson, Elizabeth

    Delay or queue length information has the potential to influence the decision of a customer to join a queue. Thus, it is imperative for managers of queueing systems to understand how the information that they provide will affect the performance of the system. To this end, we construct and analyze two two-dimensional deterministic fluid models that incorporate customer choice behavior based on delayed queue length information. In the first fluid model, customers join each queue according to a Multinomial Logit Model, however, the queue length information the customer receives is delayed by a constant Δ. We show that the delay can cause oscillations or asynchronous behavior in the model based on the value of Δ. In the second model, customers receive information about the queue length through a moving average of the queue length. Although it has been shown empirically that giving patients moving average information causes oscillations and asynchronous behavior to occur in U.S. hospitals, we analytically and mathematically show for the first time that the moving average fluid model can exhibit oscillations and determine their dependence on the moving average window. Thus, our analysis provides new insight on how operators of service systems should report queue length information to customers and how delayed information can produce unwanted system dynamics.

  3. TCP/IP Communication between Server and Client in Multi User Remote Lab Applications

    Directory of Open Access Journals (Sweden)

    Andreas Pester

    2008-07-01

    Full Text Available Remote labs in difference to virtual labs allow as usual only a single user access. To manage the user access for such remote experiments a reservation system is used. The aim of this work is to develop a simultaneous multi user access to the lab server and the remote experiment. This approach was tested for the READ remote lab and a Microcontroller remote lab, installed at the CUAS. The system controlled by LabView has been implemented using a Data Acquisition Card from National instruments. The performance of the simultaneous access was tested under load with a variable number of users. For the MRL a queue gives access to the peripherals to the main user, while the others wait for their time slot to use the system. This was implemented in such a way due to the synchronous characteristics of this lab.

  4. WMS Server 2.0

    Science.gov (United States)

    Plesea, Lucian; Wood, James F.

    2012-01-01

    This software is a simple, yet flexible server of raster map products, compliant with the Open Geospatial Consortium (OGC) Web Map Service (WMS) 1.1.1 protocol. The server is a full implementation of the OGC WMS 1.1.1 as a fastCGI client and using Geospatial Data Abstraction Library (GDAL) for data access. The server can operate in a proxy mode, where all or part of the WMS requests are done on a back server. The server has explicit support for a colocated tiled WMS, including rapid response of black (no-data) requests. It generates JPEG and PNG images, including 16-bit PNG. The GDAL back-end support allows great flexibility on the data access. The server is a port to a Linux/GDAL platform from the original IRIX/IL platform. It is simpler to configure and use, and depending on the storage format used, it has better performance than other available implementations. The WMS server 2.0 is a high-performance WMS implementation due to the fastCGI architecture. The use of GDAL data back end allows for great flexibility. The configuration is relatively simple, based on a single XML file. It provides scaling and cropping, as well as blending of multiple layers based on layer transparency.

  5. Monotonicity in the limited processor sharing queue

    NARCIS (Netherlands)

    M. Nuyens; W. van der Weij (Wemke)

    2008-01-01

    htmlabstractWe study a processor sharing queue with a limited number of service positions and an infinite buffer. The occupied service positions share an underlying resource. We prove that for service times with a decreasing failure rate, the queue length is stochastically decreasing in the number

  6. GPS queues with heterogeneous traffic classes

    NARCIS (Netherlands)

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

    2002-01-01

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

  7. Gaussian queues in light and heavy traffic

    NARCIS (Netherlands)

    Dębicki, K.; Kosiński, K.M.; Mandjes, M.

    2012-01-01

    In this paper we investigate Gaussian queues in the light-traffic and in the heavy-traffic regime. Let $Q^{(c)}_{X}\\equiv\\{Q^{(c)}_{X}(t):t\\ge0\\}$ denote a stationary buffer content process for a fluid queue fed by the centered Gaussian process X≡{X(t):t∈ℝ} with stationary increments, X(0)=0,

  8. The WIYN Queue: Theory Meets Reality

    Science.gov (United States)

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

    1998-07-01

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

  9. Openlobby: an open game server for lobby and matchmaking

    Science.gov (United States)

    Zamzami, E. M.; Tarigan, J. T.; Jaya, I.; Hardi, S. M.

    2018-03-01

    Online Multiplayer is one of the most essential feature in modern games. However, while developing a multiplayer feature can be done with a simple computer networking programming, creating a balanced multiplayer session requires more player management components such as game lobby and matchmaking system. Our objective is to develop OpenLobby, a server that available to be used by other developers to support their multiplayer application. The proposed system acts as a lobby and matchmaker where queueing players will be matched to other player according to a certain criteria defined by developer. The solution provides an application programing interface that can be used by developer to interact with the server. For testing purpose, we developed a game that uses the server as their multiplayer server.

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

    Directory of Open Access Journals (Sweden)

    faiza BELARBI

    2016-06-01

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

  11. On a generic class of two-node queueing systems

    NARCIS (Netherlands)

    Adan, Ivo; Mandjes, M.R.H.; Scheinhardt, Willem R.W.; Tzenova, Elena

    2009-01-01

    This paper analyzes a generic class of two-node queueing systems. A first queue is fed by an on–off Markov fluid source; the input of a second queue is a function of the state of the Markov fluid source as well, but now also of the first queue being empty or not. This model covers the classical

  12. Sojourn time approximations for a multi-server processor sharing system with priorities

    NARCIS (Netherlands)

    van der Mei, R.D.; van den Berg, Hans Leo; Vranken, R.; Gijsen, B.M.M.

    2003-01-01

    We study mean sojourn times in a multi-server processor sharing system with two priority classes and with general service-time distributions. For high-priority customers, the mean sojourn time follows directly from classical results on symmetric queues. For low-priority customers, in the absence of

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

    Directory of Open Access Journals (Sweden)

    Longyue Li

    2016-01-01

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

  14. GEOM/GEOM[a]/1/ queue with late arrival system with delayed access and delayed multiple working vacations

    Directory of Open Access Journals (Sweden)

    Cheng Jiang

    2014-01-01

    Full Text Available This paper considers a discrete-time bulk-service queue with infinite buffer space and delay multiple working vacations. Considering a late arrival system with delayed access (LAS-AD, it is assumed that the inter-arrival times, service times, vacation times are all geometrically distributed. The server does not take a vacation immediately at service complete epoch but keeps idle period. According to a bulk-service rule, at least one customer is needed to start a service with a maximum serving capacity 'a'. Using probability analysis method and displacement operator method, the queue length and the probability generating function of waiting time at pre-arrival epochs are obtained. Furthermore, the outside observer’s observation epoch queue length distributions are given. Finally, computational examples with numerical results in the form of graphs and tables are discussed.

  15. Queues and Lévy fluctuation theory

    CERN Document Server

    Dębicki, Krzysztof

    2015-01-01

    The book provides an extensive introduction to queueing models driven by Lévy-processes as well as a systematic account of the literature on Lévy-driven queues. The objective is to make the reader familiar with the wide set of probabilistic techniques that have been developed over the past decades, including transform-based techniques, martingales, rate-conservation arguments, change-of-measure, importance sampling, and large deviations. On the application side, it demonstrates how Lévy traffic models arise when modelling current queueing-type systems (as communication networks) and includes applications to finance. Queues and Lévy Fluctuation Theory will appeal to graduate/postgraduate students and researchers in mathematics, computer science, and electrical engineering. Basic prerequisites are probability theory and stochastic processes.

  16. An unreliable group arrival queue with k stages of service, retrial under variant vacation policy

    Science.gov (United States)

    Radha, J.; Indhira, K.; Chandrasekaran, V. M.

    2017-11-01

    In this research work we considered repairable retrial queue with group arrival and the server utilize the variant vacations. A server gives service in k stages. Any arriving group of units finds the server free, one from the group entering the first stage of service and the rest are joining into the orbit. After completion of the i th stage of service, the customer may have the option to choose (i+1)th stage of service with probability θi , with probability pi may join into orbit as feedback customer or may leave the system with probability {q}i=≤ft\\{\\begin{array}{l}1-{p}i-{θ }i,i=1,2,\\cdots k-1\\ 1-{p}i,i=k\\end{array}\\right\\}. If the orbit is empty at the service completion of each stage service, the server takes modified vacation until at least one customer appears in the orbit on the server returns from a vacation. Busy server may get to breakdown and the service channel will fail for a short interval of time. By using the supplementary variable method, steady state probability generating function for system size, some system performance measures are discussed.

  17. Preventing messaging queue deadlocks in a DMA environment

    Science.gov (United States)

    Blocksome, Michael A; Chen, Dong; Gooding, Thomas; Heidelberger, Philip; Parker, Jeff

    2014-01-14

    Embodiments of the invention may be used to manage message queues in a parallel computing environment to prevent message queue deadlock. A direct memory access controller of a compute node may determine when a messaging queue is full. In response, the DMA may generate and interrupt. An interrupt handler may stop the DMA and swap all descriptors from the full messaging queue into a larger queue (or enlarge the original queue). The interrupt handler then restarts the DMA. Alternatively, the interrupt handler stops the DMA, allocates a memory block to hold queue data, and then moves descriptors from the full messaging queue into the allocated memory block. The interrupt handler then restarts the DMA. During a normal messaging advance cycle, a messaging manager attempts to inject the descriptors in the memory block into other messaging queues until the descriptors have all been processed.

  18. On the number of observable customers, served during he busy period of GI/GI/infinity queue

    International Nuclear Information System (INIS)

    Dvurechenskij, A.

    1982-01-01

    It is proved that the number of observable customers, served during the busy period of the GI/GI infinity queue with infinitely many servers has a geometric distribution. The parameter of this distribution is determined, too. It is shown that the normalized distributions converge to the exponential distribution. As a particular result is obtained that the distribution of the number of nonabsorbing streamers in a streamer blob has a geometric distribution

  19. Queueing System with Heterogeneous Customers as a Model of a Call Center with a Call-Back for Lost Customers

    OpenAIRE

    Dudin, Sergey; Kim, Chesoong; Dudina, Olga; Baek, Janghyun

    2013-01-01

    A multiserver queueing system with infinite and finite buffers, two types of customers, and two types of servers as a model of a call center with a call-back for lost customers is investigated. Type 1 customers arrive to the system according to a Markovian arrival process. All rejected type 1 customers become type 2 customers. Type r, r=1,2, servers serve type r customers if there are any in the system and serve type r′, r′=1,2,  r′≠r, customers if there are no type r customers in the system....

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-01-01

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

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

    Science.gov (United States)

    Ryu, S.; Wakefield, S.

    2012-12-01

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

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

    International Nuclear Information System (INIS)

    Ryu, S; Wakefield, S

    2012-01-01

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

  3. GeoServer cookbook

    CERN Document Server

    Iacovella, Stefano

    2014-01-01

    This book is ideal for GIS experts, developers, and system administrators who have had a first glance at GeoServer and who are eager to explore all its features in order to configure professional map servers. Basic knowledge of GIS and GeoServer is required.

  4. A Parallel Priority Queue with Constant Time Operations

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  5. Mastering Lync Server 2010

    CERN Document Server

    Winters, Nathan

    2012-01-01

    An in-depth guide on the leading Unified Communications platform Microsoft Lync Server 2010 maximizes communication capabilities in the workplace like no other Unified Communications (UC) solution. Written by experts who know Lync Server inside and out, this comprehensive guide shows you step by step how to administer the newest and most robust version of Lync Server. Along with clear and detailed instructions, learning is aided by exercise problems and real-world examples of established Lync Server environments. You'll gain the skills you need to effectively deploy Lync Server 2010 and be on

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

    Science.gov (United States)

    2012-07-01

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

  7. Difference and differential equations with applications in queueing theory

    CERN Document Server

    Haghighi, Aliakbar Montazer

    2013-01-01

      A Useful Guide to the Interrelated Areas of Differential Equations, Difference Equations, and Queueing Models Difference and Differential Equations with Applications in Queueing Theory presents the unique connections between the methods and applications of differential equations, difference equations, and Markovian queues. Featuring a comprehensive collection of

  8. Personalized Pseudonyms for Servers in the Cloud

    Directory of Open Access Journals (Sweden)

    Xiao Qiuyu

    2017-10-01

    Full Text Available A considerable and growing fraction of servers, especially of web servers, is hosted in compute clouds. In this paper we opportunistically leverage this trend to improve privacy of clients from network attackers residing between the clients and the cloud: We design a system that can be deployed by the cloud operator to prevent a network adversary from determining which of the cloud’s tenant servers a client is accessing. The core innovation in our design is a PoPSiCl (pronounced “popsicle”, a persistent pseudonym for a tenant server that can be used by a single client to access the server, whose real identity is protected by the cloud from both passive and active network attackers. When instantiated for TLS-based access to web servers, our design works with all major browsers and requires no additional client-side software and minimal changes to the client user experience. Moreover, changes to tenant servers can be hidden in supporting software (operating systems and web-programming frameworks without imposing on web-content development. Perhaps most notably, our system boosts privacy with minimal impact to web-browsing performance, after some initial setup during a user’s first access to each web server.

  9. Server virtualization solutions

    OpenAIRE

    Lodziņš, Gunārs Ernests

    2007-01-01

    Currently in the information technology sector that is responsible for a server infrastructure is a huge development in the field of server virtualization on x86 computer architecture. As a prerequisite for such a virtualization development is growth in server productivity and underutilization of available computing power. Several companies in the market are working on two virtualization architectures – hypervizor and hosting. In this paper several of virtualization products that use host...

  10. Disk Storage Server

    CERN Multimedia

    This model was a disk storage server used in the Data Centre up until 2012. Each tray contains a hard disk drive (see the 5TB hard disk drive on the main disk display section - this actually fits into one of the trays). There are 16 trays in all per server. There are hundreds of these servers mounted on racks in the Data Centre, as can be seen.

  11. Open problems in Gaussian fluid queueing theory

    NARCIS (Netherlands)

    Dȩbicki, K.; Mandjes, M.

    2011-01-01

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

  12. QUEUEING DISCIPLINES BASED ON PRIORITY MATRIX

    Directory of Open Access Journals (Sweden)

    Taufik I. Aliev

    2014-11-01

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

  13. Unreliable Retrial Queues in a Random Environment

    Science.gov (United States)

    2007-09-01

    Visual inspection of (4.1) does not help us discern if Q∗ is a QBD. How- ever, we observe that the diagonal blocks repeat in cycles of length three...1985). Mnogokanalcprime naya sistema massovogo obsluzhivaniya v sluchaui noui srede. (Russian) [A multichannel queueing system in a random environment

  14. Dobrushin's approach to queueing network theory

    Directory of Open Access Journals (Sweden)

    F. I. Karpelevich

    1996-01-01

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

  15. Joint distributions for interacting fluid queues

    NARCIS (Netherlands)

    Kroese, Dirk; Scheinhardt, Willem R.W.

    Motivated by recent traffic control models in ATM systems, we analyse three closely related systems of fluid queues, each consisting of two consecutive reservoirs, in which the first reservoir is fed by a two-state (on and off) Markov source. The first system is an ordinary two-node fluid tandem

  16. Markov-modulated and feedback fluid queues

    NARCIS (Netherlands)

    Scheinhardt, Willem R.W.

    1998-01-01

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

  17. Labour costs and queueing theory in retailing

    NARCIS (Netherlands)

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

    1991-01-01

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

  18. Adaptive Importance Sampling Simulation of Queueing Networks

    NARCIS (Netherlands)

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

    2000-01-01

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

  19. Decomposition and aggregation in queueing networks

    NARCIS (Netherlands)

    Huisman, Tijs; Boucherie, Richardus J.; van Dijk, Nico; van Dijk, Nico M.

    2011-01-01

    This chapter considers the decomposition and aggregation of multiclass queueing networks with state-dependent routing. Combining state-dependent generalisations of quasi-reversibility and biased local balance, sufficient conditions are obtained under which the stationary distribution of the network

  20. Adaptive Filtering Queueing for Improving Fairness

    Directory of Open Access Journals (Sweden)

    Jui-Pin Yang

    2015-06-01

    Full Text Available In this paper, we propose a scalable and efficient Active Queue Management (AQM scheme to provide fair bandwidth sharing when traffic is congested dubbed Adaptive Filtering Queueing (AFQ. First, AFQ identifies the filtering level of an arriving packet by comparing it with a flow label selected at random from the first level to an estimated level in the filtering level table. Based on the accepted traffic estimation and the previous fair filtering level, AFQ updates the fair filtering level. Next, AFQ uses a simple packet-dropping algorithm to determine whether arriving packets are accepted or discarded. To enhance AFQ’s feasibility in high-speed networks, we propose a two-layer mapping mechanism to effectively simplify the packet comparison operations. Simulation results demonstrate that AFQ achieves optimal fairness when compared with Rotating Preference Queues (RPQ, Core-Stateless Fair Queueing (CSFQ, CHOose and Keep for responsive flows, CHOose and Kill for unresponsive flows (CHOKe and First-In First-Out (FIFO schemes under a variety of traffic conditions.

  1. Markov queue game with virtual reality strategies | Nwobi-Okoye ...

    African Journals Online (AJOL)

    A non cooperative markov game with several unique characteristics was introduced. Some of these characteristics include: the existence of a single phase multi server queuing model and markovian transition matrix/matrices for each game, introduction of virtual situations (virtual reality) or dummies to improve the chances ...

  2. Migrasi dari Windows Server ke Linux Server Studi Kasus: Server POLY050

    OpenAIRE

    Winoto, Basuki; Wardani, Deni

    2005-01-01

    File, as an important aspect of personal computer USAge, can be managed personally by the ownerhimself or centralized in file storage servers. File storage server in Windows network environment use a specificcommunication protocol called SMB. This protocol, instead of being used by Windows Server, can also used bya server application called Samba which runs on Linux. Therefore, file storage server migration from WindowsServer to Linux Server is possible.

  3. Network characteristics for server selection in online games

    Science.gov (United States)

    Claypool, Mark

    2008-01-01

    Online gameplay is impacted by the network characteristics of players connected to the same server. Unfortunately, the network characteristics of online game servers are not well-understood, particularly for groups that wish to play together on the same server. As a step towards a remedy, this paper presents analysis of an extensive set of measurements of game servers on the Internet. Over the course of many months, actual Internet game servers were queried simultaneously by twenty-five emulated game clients, with both servers and clients spread out on the Internet. The data provides statistics on the uptime and populations of game servers over a month long period an an in-depth look at the suitability for game servers for multi-player server selection, concentrating on characteristics critical to playability--latency and fairness. Analysis finds most game servers have latencies suitable for third-person and omnipresent games, such as real-time strategy, sports and role-playing games, providing numerous server choices for game players. However, far fewer game servers have the low latencies required for first-person games, such as shooters or race games. In all cases, groups that wish to play together have a greatly reduced set of servers from which to choose because of inherent unfairness in server latencies and server selection is particularly limited as the group size increases. These results hold across different game types and even across different generations of games. The data should be useful for game developers and network researchers that seek to improve game server selection, whether for single or multiple players.

  4. Large deviations for tandem queueing systems

    Directory of Open Access Journals (Sweden)

    Roland L. Dobrushin

    1994-01-01

    Full Text Available The crude asymptotics of the large delay probability in a tandem queueing system is considered. The main result states that one of the two channels in the tandem system defines the crude asymptotics. The constant that determines the crude asymptotics is given. The results obtained are based on the large deviation principle for random processes with independent increments on an infinite interval recently established by the authors.

  5. Linux Server Security

    CERN Document Server

    Bauer, Michael D

    2005-01-01

    Linux consistently appears high up in the list of popular Internet servers, whether it's for the Web, anonymous FTP, or general services such as DNS and delivering mail. But security is the foremost concern of anyone providing such a service. Any server experiences casual probe attempts dozens of time a day, and serious break-in attempts with some frequency as well. This highly regarded book, originally titled Building Secure Servers with Linux, combines practical advice with a firm knowledge of the technical tools needed to ensure security. The book focuses on the most common use of Linux--

  6. Improving SQL Server Perform

    Directory of Open Access Journals (Sweden)

    Nicolae MERCIOIU

    2010-01-01

    Full Text Available With the development of client server technology and multilayer architectures the systems ef-ficiency issue has been increasingly discussed. Lacking knowledge in optimization methods and tools offered by DBMS's, database administrators and developers of applications based on Microsoft technologies cannot optimally design and service performing systems. In this article we review the objectives that should be considered (in order to improve performance of SQL Server instances and we describe the techniques used to optimize queries. Also, we explain and illustrate the new optimization features offered by SQL Server 2008.

  7. Learning Zimbra Server essentials

    CERN Document Server

    Kouka, Abdelmonam

    2013-01-01

    A standard tutorial approach which will guide the readers on all of the intricacies of the Zimbra Server.If you are any kind of Zimbra user, this book will be useful for you, from newbies to experts who would like to learn how to setup a Zimbra server. If you are an IT administrator or consultant who is exploring the idea of adopting, or have already adopted Zimbra as your mail server, then this book is for you. No prior knowledge of Zimbra is required.

  8. Compute Server Performance Results

    Science.gov (United States)

    Stockdale, I. E.; Barton, John; Woodrow, Thomas (Technical Monitor)

    1994-01-01

    Parallel-vector supercomputers have been the workhorses of high performance computing. As expectations of future computing needs have risen faster than projected vector supercomputer performance, much work has been done investigating the feasibility of using Massively Parallel Processor systems as supercomputers. An even more recent development is the availability of high performance workstations which have the potential, when clustered together, to replace parallel-vector systems. We present a systematic comparison of floating point performance and price-performance for various compute server systems. A suite of highly vectorized programs was run on systems including traditional vector systems such as the Cray C90, and RISC workstations such as the IBM RS/6000 590 and the SGI R8000. The C90 system delivers 460 million floating point operations per second (FLOPS), the highest single processor rate of any vendor. However, if the price-performance ration (PPR) is considered to be most important, then the IBM and SGI processors are superior to the C90 processors. Even without code tuning, the IBM and SGI PPR's of 260 and 220 FLOPS per dollar exceed the C90 PPR of 160 FLOPS per dollar when running our highly vectorized suite,

  9. Near optimal admission control for multiserver loss queues in series

    OpenAIRE

    Ku, Cheng-Yuan; Jordan, Scott

    2003-01-01

    This paper considers access control policies in multiserver loss queues in series such as might arise in the context of computer and telecommunication networks. Each queue is presented with both served upstream customers and Poisson arrivals from outside the network, and it may route serviced customers out of the network or to the downstream queue. Service times of each customer are i.i.d. and exponentially distributed. Revenue is earned by each station when it serves a customer, but the amou...

  10. Locating Hidden Servers

    National Research Council Canada - National Science Library

    Oeverlier, Lasse; Syverson, Paul F

    2006-01-01

    .... Announced properties include server resistance to distributed DoS. Both the EFF and Reporters Without Borders have issued guides that describe using hidden services via Tor to protect the safety of dissidents as well as to resist censorship...

  11. Server hardware trends

    CERN Multimedia

    CERN. Geneva

    2014-01-01

    This talk will cover the status of the current and upcoming offers on server platforms, focusing mainly on the processing and storage parts. Alternative solutions like Open Compute (OCP) will be quickly covered.

  12. Remote diagnosis server

    Science.gov (United States)

    Deb, Somnath (Inventor); Ghoshal, Sudipto (Inventor); Malepati, Venkata N. (Inventor); Kleinman, David L. (Inventor); Cavanaugh, Kevin F. (Inventor)

    2004-01-01

    A network-based diagnosis server for monitoring and diagnosing a system, the server being remote from the system it is observing, comprises a sensor for generating signals indicative of a characteristic of a component of the system, a network-interfaced sensor agent coupled to the sensor for receiving signals therefrom, a broker module coupled to the network for sending signals to and receiving signals from the sensor agent, a handler application connected to the broker module for transmitting signals to and receiving signals therefrom, a reasoner application in communication with the handler application for processing, and responding to signals received from the handler application, wherein the sensor agent, broker module, handler application, and reasoner applications operate simultaneously relative to each other, such that the present invention diagnosis server performs continuous monitoring and diagnosing of said components of the system in real time. The diagnosis server is readily adaptable to various different systems.

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

    DEFF Research Database (Denmark)

    Raovic, Nevena

    into account (Bliemer, 2008). Yperman (2007) indicates that there is a significant difference in queue-propagation and queue-dissipation between the LTM and DQM. This results in different route travel times, and can further affect route choice. In this paper, different approaches to represent queue propagation...... and dissipation through the CTM, LTM and DQM are studied. A simple network allows to show how these approaches influence route travel time. Furthermore, the possibility of changing the existing DQM is considered in order to more realistically represent queue propagation and dissipation, which would lead to more...... accurate route travel times....

  14. An Application Server for Scientific Collaboration

    Science.gov (United States)

    Cary, John R.; Luetkemeyer, Kelly G.

    1998-11-01

    Tech-X Corporation has developed SciChat, an application server for scientific collaboration. Connections are made to the server through a Java client, that can either be an application or an applet served in a web page. Once connected, the client may choose to start or join a session. A session includes not only other clients, but also an application. Any client can send a command to the application. This command is executed on the server and echoed to all clients. The results of the command, whether numerical or graphical, are then distributed to all of the clients; thus, multiple clients can interact collaboratively with a single application. The client is developed in Java, the server in C++, and the middleware is the Common Object Request Broker Architecture. In this system, the Graphical User Interface processing is on the client machine, so one does not have the disadvantages of insufficient bandwidth as occurs when running X over the internet. Because the server, client, and middleware are object oriented, new types of servers and clients specialized to particular scientific applications are more easily developed.

  15. Design and Implementation of Streaming Media Server Cluster Based on FFMpeg

    Science.gov (United States)

    Zhao, Hong; Zhou, Chun-long; Jin, Bao-zhao

    2015-01-01

    Poor performance and network congestion are commonly observed in the streaming media single server system. This paper proposes a scheme to construct a streaming media server cluster system based on FFMpeg. In this scheme, different users are distributed to different servers according to their locations and the balance among servers is maintained by the dynamic load-balancing algorithm based on active feedback. Furthermore, a service redirection algorithm is proposed to improve the transmission efficiency of streaming media data. The experiment results show that the server cluster system has significantly alleviated the network congestion and improved the performance in comparison with the single server system. PMID:25734187

  16. Design and implementation of streaming media server cluster based on FFMpeg.

    Science.gov (United States)

    Zhao, Hong; Zhou, Chun-long; Jin, Bao-zhao

    2015-01-01

    Poor performance and network congestion are commonly observed in the streaming media single server system. This paper proposes a scheme to construct a streaming media server cluster system based on FFMpeg. In this scheme, different users are distributed to different servers according to their locations and the balance among servers is maintained by the dynamic load-balancing algorithm based on active feedback. Furthermore, a service redirection algorithm is proposed to improve the transmission efficiency of streaming media data. The experiment results show that the server cluster system has significantly alleviated the network congestion and improved the performance in comparison with the single server system.

  17. Analisis Perbandingan Load Balancing Web Server Tunggal Dengan Web Server Cluster Menggunakan Linux Virtual Server

    OpenAIRE

    Lukitasari, Desy; Oklilas, Ahmad Fali

    2010-01-01

    Virtual server adalah server yang mempunyai skalabilitas dan ketersedian yang tinggi yang dibangun diatas sebuah cluster dari beberapa real server. Real server dan load balancer akan saling terkoneksi baik dalam jaringan lokal kecepatan tinggi atau yang terpisah secara geografis. Load balancer dapat mengirim permintaan-permintaan ke server yang berbeda dan membuat paralel service dari sebuah cluster pada sebuah alamat IP tunggal dan meminta pengiriman dapat menggunakan teknologi IP load...

  18. Adaptive optimization for active queue management supporting TCP flows

    NARCIS (Netherlands)

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

    2016-01-01

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

  19. 2-Layered Architecture of Vague Logic Based Multilevel Queue Scheduler

    Directory of Open Access Journals (Sweden)

    Supriya Raheja

    2014-01-01

    Full Text Available In operating system the decisions which CPU scheduler makes regarding the sequence and length of time the task may run are not easy ones, as the scheduler has only a limited amount of information about the tasks. A good scheduler should be fair, maximizes throughput, and minimizes response time of system. A scheduler with multilevel queue scheduling partitions the ready queue into multiple queues. While assigning priorities, higher level queues always get more priorities over lower level queues. Unfortunately, sometimes lower priority tasks get starved, as the scheduler assures that the lower priority tasks may be scheduled only after the higher priority tasks. While making decisions scheduler is concerned only with one factor, that is, priority, but ignores other factors which may affect the performance of the system. With this concern, we propose a 2-layered architecture of multilevel queue scheduler based on vague set theory (VMLQ. The VMLQ scheduler handles the impreciseness of data as well as improving the starvation problem of lower priority tasks. This work also optimizes the performance metrics and improves the response time of system. The performance is evaluated through simulation using MatLab. Simulation results prove that the VMLQ scheduler performs better than the classical multilevel queue scheduler and fuzzy based multilevel queue scheduler.

  20. 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

  1. Discrete-time retrial queue with Bernoulli vacation, preemptive resume and feedback customers

    Directory of Open Access Journals (Sweden)

    Peishu Chen

    2015-09-01

    Full Text Available Purpose: We consider a discrete-time Geo/G/1 retrial queue where the retrial time follows a general distribution, the server subject to Bernoulli vacation policy and the customer has preemptive resume priority, Bernoulli feedback strategy. The main purpose of this paper is to derive the generating functions of the stationary distribution of the system state, the orbit size and some important performance measures. Design/methodology: Using probability generating function technique, some valuable and interesting performance measures of the system are obtained. We also investigate two stochastic decomposition laws and present some numerical results. Findings: We obtain the probability generating functions of the system state distribution as well as those of the orbit size and the system size distributions. We also obtain some analytical expressions for various performance measures such as idle and busy probabilities, mean orbit and system sizes. Originality/value: The analysis of discrete-time retrial queues with Bernoulli vacation, preemptive resume and feedback customers is interesting and to the best of our knowledge, no other scientific journal paper has dealt with this question. This fact gives the reason why efforts should be taken to plug this gap.

  2. STATIONARY DISTRIBUTION OF A TANDEM QUEUE WITH ADDITIONAL FLOWS ON THE STATIONS OF THE TANDEM

    Directory of Open Access Journals (Sweden)

    V. I. Klimenok

    2017-01-01

    Full Text Available A tandem queueing system consisting of a finite number of multi-server stations without buffers is analized. The input flow at the first station is a ???????????? (Markovian arrival process. The customers from this flow aim to be served at all stations of the tandem. For any station, besides transit customers proceeding from the previous station, an additional ???????????? flow of new customers arrives at this station directly. Customers from this flow aim to be served at this station and all subsequent stations of the tandem. The service times of customer at the stations are exponentially distributed with the service rate depending of number of the station. The algorithms for culculation of stationary distributions and the loss probabilities associated with the tandem are given.

  3. The RNAsnp web server

    DEFF Research Database (Denmark)

    Radhakrishnan, Sabarinathan; Tafer, Hakim; Seemann, Ernst Stefan

    2013-01-01

    , are derived from extensive pre-computed tables of distributions of substitution effects as a function of gene length and GC content. Here, we present a web service that not only provides an interface for RNAsnp but also features a graphical output representation. In addition, the web server is connected...... to a local mirror of the UCSC genome browser database that enables the users to select the genomic sequences for analysis and visualize the results directly in the UCSC genome browser. The RNAsnp web server is freely available at: http://rth.dk/resources/rnasnp/....

  4. Windows Terminal Servers Orchestration

    Science.gov (United States)

    Bukowiec, Sebastian; Gaspar, Ricardo; Smith, Tim

    2017-10-01

    Windows Terminal Servers provide application gateways for various parts of the CERN accelerator complex, used by hundreds of CERN users every day. The combination of new tools such as Puppet, HAProxy and Microsoft System Center suite enable automation of provisioning workflows to provide a terminal server infrastructure that can scale up and down in an automated manner. The orchestration does not only reduce the time and effort necessary to deploy new instances, but also facilitates operations such as patching, analysis and recreation of compromised nodes as well as catering for workload peaks.

  5. SHADE3 server

    DEFF Research Database (Denmark)

    Madsen, Anders Østergaard; Hoser, Anna Agnieszka

    2014-01-01

    A major update of the SHADE server (http://shade.ki.ku.dk) is presented. In addition to all of the previous options for estimating H-atom anisotropic displacement parameters (ADPs) that were offered by SHADE2, the newest version offers two new methods. The first method combines the original....... Tools are provided to set up the ab initio calculations and to derive the internal motion from the calculations. The new server was tested on a range of compounds where neutron diffraction data were available. In most cases, the results are significantly better than previous estimates, and for strong...

  6. NExT server

    CERN Multimedia

    1989-01-01

    The first website at CERN - and in the world - was dedicated to the World Wide Web project itself and was hosted on Berners-Lee's NeXT computer. The website described the basic features of the web; how to access other people's documents and how to set up your own server. This NeXT machine - the original web server - is still at CERN. As part of the project to restore the first website, in 2013 CERN reinstated the world's first website to its original address.

  7. Professional SQL Server 2005 administration

    CERN Document Server

    Knight, Brian; Snyder, Wayne; Armand, Jean-Claude; LoForte, Ross; Ji, Haidong

    2007-01-01

    SQL Server 2005 is the largest leap forward for SQL Server since its inception. With this update comes new features that will challenge even the most experienced SQL Server DBAs. Written by a team of some of the best SQL Server experts in the industry, this comprehensive tutorial shows you how to navigate the vastly changed landscape of the SQL Server administration. Drawing on their own first-hand experiences to offer you best practices, unique tips and tricks, and useful workarounds, the authors help you handle even the most difficult SQL Server 2005 administration issues, including blockin

  8. HexServer: an FFT-based protein docking server powered by graphics processors.

    Science.gov (United States)

    Macindoe, Gary; Mavridis, Lazaros; Venkatraman, Vishwesh; Devignes, Marie-Dominique; Ritchie, David W

    2010-07-01

    HexServer (http://hexserver.loria.fr/) is the first Fourier transform (FFT)-based protein docking server to be powered by graphics processors. Using two graphics processors simultaneously, a typical 6D docking run takes approximately 15 s, which is up to two orders of magnitude faster than conventional FFT-based docking approaches using comparable resolution and scoring functions. The server requires two protein structures in PDB format to be uploaded, and it produces a ranked list of up to 1000 docking predictions. Knowledge of one or both protein binding sites may be used to focus and shorten the calculation when such information is available. The first 20 predictions may be accessed individually, and a single file of all predicted orientations may be downloaded as a compressed multi-model PDB file. The server is publicly available and does not require any registration or identification by the user.

  9. Scheduling of multi-class multi-server queueing systems with abandonments

    Czech Academy of Sciences Publication Activity Database

    Ayesta, U.; Jacko, P.; Novák, Vladimír

    2017-01-01

    Roč. 20, č. 2 (2017), s. 129-145 ISSN 1094-6136 R&D Projects: GA MŠk(CZ) SVV260475 Institutional support: Progres-Q24 Keywords : stochastic scheduling * abandonment * restless bandits Subject RIV: AH - Economics OBOR OECD: Economic Theory Impact factor: 1.281, year: 2016

  10. A closed-form solution for a two-server heterogeneous retrial queue ...

    Indian Academy of Sciences (India)

    Division of Knowledge and System Engineering for ICT, Faculty of Information Technology, Ton Duc Thang University, Ho Chi Minh City, Vietnam; Department of Networked Systems and Services, Budapest University of Technology and Economics, H-117, Magyar tudo ´sok ko ¨ru ´tja 2, Budapest, Hungary; RGM College of ...

  11. DNS BIND Server Configuration

    Directory of Open Access Journals (Sweden)

    Radu MARSANU

    2011-01-01

    Full Text Available After a brief presentation of the DNS and BIND standard for Unix platforms, the paper presents an application which has a principal objective, the configuring of the DNS BIND 9 server. The general objectives of the application are presented, follow by the description of the details of designing the program.

  12. DNS BIND Server Configuratio

    OpenAIRE

    Radu MARSANU

    2011-01-01

    After a brief presentation of the DNS and BIND standard for Unix platforms, the paper presents an application which has a principal objective, the configuring of the DNS BIND 9 server. The general objectives of the application are presented, follow by the description of the details of designing the program.

  13. DNS BIND Server Configuration

    OpenAIRE

    Radu MARSANU

    2011-01-01

    After a brief presentation of the DNS and BIND standard for Unix platforms, the paper presents an application which has a principal objective, the configuring of the DNS BIND 9 server. The general objectives of the application are presented, follow by the description of the details of designing the program.

  14. Dali server update.

    Science.gov (United States)

    Holm, Liisa; Laakso, Laura M

    2016-07-08

    The Dali server (http://ekhidna2.biocenter.helsinki.fi/dali) is a network service for comparing protein structures in 3D. In favourable cases, comparing 3D structures may reveal biologically interesting similarities that are not detectable by comparing sequences. The Dali server has been running in various places for over 20 years and is used routinely by crystallographers on newly solved structures. The latest update of the server provides enhanced analytics for the study of sequence and structure conservation. The server performs three types of structure comparisons: (i) Protein Data Bank (PDB) search compares one query structure against those in the PDB and returns a list of similar structures; (ii) pairwise comparison compares one query structure against a list of structures specified by the user; and (iii) all against all structure comparison returns a structural similarity matrix, a dendrogram and a multidimensional scaling projection of a set of structures specified by the user. Structural superimpositions are visualized using the Java-free WebGL viewer PV. The structural alignment view is enhanced by sequence similarity searches against Uniprot. The combined structure-sequence alignment information is compressed to a stack of aligned sequence logos. In the stack, each structure is structurally aligned to the query protein and represented by a sequence logo. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

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

    NARCIS (Netherlands)

    Bosman, J.W.; Núñez-Queija, R.

    2014-01-01

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

  16. Performance optimization of queueing systems with perturbation realization

    KAUST Repository

    Xia, Li

    2012-04-01

    After the intensive studies of queueing theory in the past decades, many excellent results in performance analysis have been obtained, and successful examples abound. However, exploring special features of queueing systems directly in performance optimization still seems to be a territory not very well cultivated. Recent progresses of perturbation analysis (PA) and sensitivity-based optimization provide a new perspective of performance optimization of queueing systems. PA utilizes the structural information of queueing systems to efficiently extract the performance sensitivity information from a sample path of system. This paper gives a brief review of PA and performance optimization of queueing systems, focusing on a fundamental concept called perturbation realization factors, which captures the special dynamic feature of a queueing system. With the perturbation realization factors as building blocks, the performance derivative formula and performance difference formula can be obtained. With performance derivatives, gradient-based optimization can be derived, while with performance difference, policy iteration and optimality equations can be derived. These two fundamental formulas provide a foundation for performance optimization of queueing systems from a sensitivity-based point of view. We hope this survey may provide some inspirations on this promising research topic. © 2011 Elsevier B.V. All rights reserved.

  17. Probability, statistics and queueing theory, with computer science applications

    CERN Document Server

    Allen, Arnold O

    1978-01-01

    Probability, Statistics, and Queueing Theory: With Computer Science Applications focuses on the use of statistics and queueing theory for the design and analysis of data communication systems, emphasizing how the theorems and theory can be used to solve practical computer science problems. This book is divided into three parts. The first part discusses the basic concept of probability, probability distributions commonly used in applied probability, and important concept of a stochastic process. Part II covers the discipline of queueing theory, while Part III deals with statistical inference. T

  18. A study on M/G/1 retrial G - queue with two phases of service, immediate feedback and working vacations

    Science.gov (United States)

    Varalakshmi, M.; Chandrasekaran, V. M.; Saravanarajan, M. C.

    2017-11-01

    In this paper, we discuss about the steady state behaviour of M/G/1 retrial queueing system with two phases of services and immediate feedbacks under working vacation policy where the regular busy server is affected due to the arrival of negative customers. Upon arrival if the customer finds the server busy, breakdown or on working vacation it enters an orbit; otherwise the customer enters into the service area immediately. After service completion, the customer is allowed to make finite number of immediate feedback. The feedback service also consists of two phases. At the service completion epoch of a positive customer, if the orbit is empty the server goes for a working vacation. The server works at a lower service rate during working vacation (WV) period. Using the supplementary variable technique, we found out the steady state probability generating function for the system and in orbit. System performance measures and reliability measures are discussed. Finally, some numerical examples are presented to validate the analyticalresults.

  19. Rancang Bangun Server Learning Management System Menggunakan Load Balancer dan Reverse Proxy

    Directory of Open Access Journals (Sweden)

    Sirajuddin Sirajuddin

    2012-09-01

    Full Text Available Salah satu solusi untuk mengatasi masalah beban pada web server adalah dengan menggunakan lebih dari satu web server. Trafik internet akan dikendalikan oleh load balancer yang akan membagi request yang diterimanya ke masing-masing web server. Selain load balancer bisa juga dipasang reverse proxy untuk men-cache halaman web sehingga bisa di-load lebih cepat lagi. Rancang bangun sistem yang diuji dalam tugas akhir ini meliputi dua web server Learning Management System (LMS yang dikontrol oleh satu load balancer dan reverse proxy (cluster. Pengujian juga dilakukan pada server LMS single untuk dijadikan tolok ukur perbandingan. Pengujian dilakukan untuk mengamati perbedaan performansi yang dicapai server LMS cluster dibandingkan dengan server LMS single. Dari hasil pengujian didapatkan bahwa server LMS cluster mampu meningkatkan performansi secara signifikan ketika jumlah user yang mengakses berjumlah lebih dari 40 user. Peningkatan tersebut terutama terlihat pada parameter throughput, packet retransmission dan page load time yang mampu meningkat sampai 57.93%.

  20. Windows Home Server users guide

    CERN Document Server

    Edney, Andrew

    2008-01-01

    Windows Home Server brings the idea of centralized storage, backup and computer management out of the enterprise and into the home. Windows Home Server is built for people with multiple computers at home and helps to synchronize them, keep them updated, stream media between them, and back them up centrally. Built on a similar foundation as the Microsoft server operating products, it's essentially Small Business Server for the home.This book details how to install, configure, and use Windows Home Server and explains how to connect to and manage different clients such as Windows XP, Windows Vist

  1. Microsoft SQL Server 2012 bible

    CERN Document Server

    Jorgensen, Adam; LeBlanc, Patrick; Cherry, Denny; Nelson, Aaron

    2012-01-01

    Harness the powerful new SQL Server 2012 Microsoft SQL Server 2012 is the most significant update to this product since 2005, and it may change how database administrators and developers perform many aspects of their jobs. If you're a database administrator or developer, Microsoft SQL Server 2012 Bible teaches you everything you need to take full advantage of this major release. This detailed guide not only covers all the new features of SQL Server 2012, it also shows you step by step how to develop top-notch SQL Server databases and new data connections and keep your databases performing at p

  2. Mastering Microsoft Exchange Server 2010

    CERN Document Server

    McBee, Jim

    2010-01-01

    A top-selling guide to Exchange Server-now fully updated for Exchange Server 2010. Keep your Microsoft messaging system up to date and protected with the very newest version, Exchange Server 2010, and this comprehensive guide. Whether you're upgrading from Exchange Server 2007 SP1 or earlier, installing for the first time, or migrating from another system, this step-by-step guide provides the hands-on instruction, practical application, and real-world advice you need.: Explains Microsoft Exchange Server 2010, the latest release of Microsoft's messaging system that protects against spam and vir

  3. Beginning SQL Server 2008 Administration

    CERN Document Server

    Walters, R

    2009-01-01

    Beginning SQL Server 2008 Administration is essential for anyone wishing to learn about implementing and managing SQL Server 2008 database. From college students, to experienced database administrators from other platforms, to those already familiar with SQL Server and wanting to fill in some gaps of knowledge, this book will bring all readers up to speed on the enterprise platform Microsoft SQL Server 2008. * Clearly describes relational database concepts* Explains the SQL Server database engine and supporting tools* Shows various database maintenance scenarios What you'll learn* Understand c

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

    Science.gov (United States)

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

    2018-01-01

    Delay Tolerant Network (DTN) multi-copy routing protocols are privileged to create and transmit multiple copies of each message that causes congestion and some messages are dropped. This process is known as reactive drop because messages were dropped re-actively to overcome buffer overflows. The existing reactive buffer management policies apply a single metric to drop source, relay and destine messages. Hereby, selection to drop a message is dubious because each message as source, relay or destine may have consumed dissimilar magnitude of network resources. Similarly, DTN has included time to live (ttl) parameter which defines lifetime of message. Hence, when ttl expires then message is automatically destroyed from relay nodes. However, time-to-live (ttl) is not applicable on messages reached at their destinations. Moreover, nodes keep replicating messages till ttl expires even-though large number of messages has already been dispersed. In this paper, we have proposed Priority Queue Based Reactive Buffer Management Policy (PQB-R) for DTN under City Based Environments. The PQB-R classifies buffered messages into source, relay and destine queues. Moreover, separate drop metric has been applied on individual queue. The experiment results prove that proposed PQB-R has reduced number of messages transmissions, message drop and increases delivery ratio. PMID:29438438

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

    Directory of Open Access Journals (Sweden)

    Qaisar Ayub

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

  6. Simple queueing approach to segregation dynamics in Schelling model

    OpenAIRE

    Sobkowicz, Pawel

    2007-01-01

    A simple queueing approach for segregation of agents in modified one dimensional Schelling segregation model is presented. The goal is to arrive at simple formula for the number of unhappy agents remaining after the segregation.

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

    OpenAIRE

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

    1995-01-01

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

  8. A message queue based event notification system : football lottery system

    OpenAIRE

    Xu, Yunpeng

    2010-01-01

    Master's thesis in Computer science The event notification service enables user of getting informed about the occurrence of their events of interest. Message queue technology provides asynchronous message exchange functions between computer processes. This thesis presents a solution of building event notification system using the message queue approach. The events in the experiment are generated during the football match and used for both stateless and stateful processing. ...

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

    Science.gov (United States)

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

    2012-02-07

    Embodiments of the invention may be used to manage message queues in a parallel computing environment to prevent message queue deadlock. A direct memory access controller of a compute node may determine when a messaging queue is full. In response, the DMA may generate an interrupt. An interrupt handler may stop the DMA and swap all descriptors from the full messaging queue into a larger queue (or enlarge the original queue). The interrupt handler then restarts the DMA. Alternatively, the interrupt handler stops the DMA, allocates a memory block to hold queue data, and then moves descriptors from the full messaging queue into the allocated memory block. The interrupt handler then restarts the DMA. During a normal messaging advance cycle, a messaging manager attempts to inject the descriptors in the memory block into other messaging queues until the descriptors have all been processed.

  10. The transient M/G/1/0 queue: some bounds and approximations for light traffic with application to reliability

    Directory of Open Access Journals (Sweden)

    J. Ben Atkinson

    1995-01-01

    Full Text Available We consider the transient analysis of the M/G/1/0 queue, for which Pn(t denotes the probability that there are no customers in the system at time t, given that there are n(n=0,1 customers in the system at time 0. The analysis, which is based upon coupling theory, leads to simple bounds on Pn(t for the M/G/1/0 and M/PH/1/0 queues and improved bounds for the special case M/Er/1/0. Numerical results are presented for various values of the mean arrival rate λ to demonstrate the increasing accuracy of approximations based upon the above bounds in light traffic, i.e., as λ→0. An important area of application for the M/G/1/0 queue is as a reliability model for a single repairable component. Since most practical reliability problems have λ values that are small relative to the mean service rate, the approximations are potentially useful in that context. A duality relation between the M/G/1/0 and GI/M/1/0 queues is also described.

  11. Client/server study

    Science.gov (United States)

    Dezhgosha, Kamyar; Marcus, Robert; Brewster, Stephen

    1995-01-01

    The goal of this project is to find cost-effective and efficient strategies/solutions to integrate existing databases, manage network, and improve productivity of users in a move towards client/server and Integrated Desktop Environment (IDE) at NASA LeRC. The project consisted of two tasks as follows: (1) Data collection, and (2) Database Development/Integration. Under task 1, survey questionnaires and a database were developed. Also, an investigation on commercially available tools for automated data-collection and net-management was performed. As requirements evolved, the main focus has been task 2 which involved the following subtasks: (1) Data gathering/analysis of database user requirements, (2) Database analysis and design, making recommendations for modification of existing data structures into relational database or proposing a common interface to access heterogeneous databases(INFOMAN system, CCNS equipment list, CCNS software list, USERMAN, and other databases), (3) Establishment of a client/server test bed at Central State University (CSU), (4) Investigation of multi-database integration technologies/ products for IDE at NASA LeRC, and (5) Development of prototypes using CASE tools (Object/View) for representative scenarios accessing multi-databases and tables in a client/server environment. Both CSU and NASA LeRC have benefited from this project. CSU team investigated and prototyped cost-effective/practical solutions to facilitate NASA LeRC move to a more productive environment. CSU students utilized new products and gained skills that could be a great resource for future needs of NASA.

  12. SQL Server Integration Services

    CERN Document Server

    Hamilton, Bill

    2007-01-01

    SQL Server 2005 Integration Services (SSIS) lets you build high-performance data integration solutions. SSIS solutions wrap sophisticated workflows around tasks that extract, transform, and load (ETL) data from and to a wide variety of data sources. This Short Cut begins with an overview of key SSIS concepts, capabilities, standard workflow and ETL elements, the development environment, execution, deployment, and migration from Data Transformation Services (DTS). Next, you'll see how to apply the concepts you've learned through hands-on examples of common integration scenarios. Once you've

  13. Microsoft Windows Server Administration Essentials

    CERN Document Server

    Carpenter, Tom

    2011-01-01

    The core concepts and technologies you need to administer a Windows Server OS Administering a Windows operating system (OS) can be a difficult topic to grasp, particularly if you are new to the field of IT. This full-color resource serves as an approachable introduction to understanding how to install a server, the various roles of a server, and how server performance and maintenance impacts a network. With a special focus placed on the new Microsoft Technology Associate (MTA) certificate, the straightforward, easy-to-understand tone is ideal for anyone new to computer administration looking t

  14. Mastering Microsoft Exchange Server 2013

    CERN Document Server

    Elfassy, David

    2013-01-01

    The bestselling guide to Exchange Server, fully updated for the newest version Microsoft Exchange Server 2013 is touted as a solution for lowering the total cost of ownership, whether deployed on-premises or in the cloud. Like the earlier editions, this comprehensive guide covers every aspect of installing, configuring, and managing this multifaceted collaboration system. It offers Windows systems administrators and consultants a complete tutorial and reference, ideal for anyone installing Exchange Server for the first time or those migrating from an earlier Exchange Server version.Microsoft

  15. Sending servers to Morocco

    CERN Multimedia

    Joannah Caborn Wengler

    2012-01-01

    Did you know that computer centres are like people? They breathe air in and out like a person, they have to be kept at the right temperature, and they can even be organ donors. As part of a regular cycle of equipment renewal, the CERN Computer Centre has just donated 161 retired servers to universities in Morocco.   Prof. Abdeslam Hoummada and CERN DG Rolf Heuer seeing off the servers on the beginning of their journey to Morocco. “Many people don’t realise, but the Computer Centre is like a living thing. You don’t just install equipment and it runs forever. We’re continually replacing machines, broken parts and improving things like the cooling.” Wayne Salter, Leader of the IT Computing Facilities Group, watches over the Computer Centre a bit like a nurse monitoring a patient’s temperature, especially since new international recommendations for computer centre environmental conditions were released. “A new international s...

  16. Cluster Server IPTV dengan Penjadwalan Algoritma Round Robin

    Directory of Open Access Journals (Sweden)

    Didik Aribowo

    2016-03-01

    Full Text Available Perkembangan teknologi informasi yang pesat, otomatis seiring juga dengan meningkatnya para pengguna yang terhubung pada jaringan internet. Berawal dari sebuah single server yang selalu mendapatkan request dari banyak user, perlahan tapi pasti akan terjadi overload dan crash sehingga berdampak pada request yang tidak dapat dilayani oleh single server. Desain arsitektur cluster dapat dibangun dengan menggunakan konsep network load balancing yang memungkinkan proses pengolahan data di share ke dalam beberapa komputer. Dalam penelitian ini menggunakan algoritma penjadwalan round robin sebagai solusi alternatif mengatasi permasalah overload data pada server yang dapat mempengaruhi kinerja sistem IPTV. Untuk  jumlah request yang digunakan dalam penelitian ini adalah 5000, 15000, 25000, dan 50000 request. Dengan metode tersebut, maka performansi algoritma penjawalan dapat diamati dengan menekankan pada parameter sebagai berikut, yaitu throughput, respon time, reply connection, dan error connection sehingga didapatkan algoritma penjadwalan terbaik dalam rangka optimalisasi cluster server IPTV. Secara otomatis dalam proses load balancing mampu mengurangi beban kerja setiap server sehingga tidak ada server yang overload dan memungkinkan server  menggunakan bandwidth  yang tersedia secara lebih efektif serta menyediakan akses yang cepat ke web browser yang dihosting. Implementasi webserver cluster dengan skema load balancing dapat memberikan alvalaibilitas sistem yang tetap terjaga dan skalabilitas yang cukup untuk dapat tetap melayani setiap request dari pengguna

  17. Secure entanglement distillation for double-server blind quantum computation.

    Science.gov (United States)

    Morimae, Tomoyuki; Fujii, Keisuke

    2013-07-12

    Blind quantum computation is a new secure quantum computing protocol where a client, who does not have enough quantum technologies at her disposal, can delegate her quantum computation to a server, who has a fully fledged quantum computer, in such a way that the server cannot learn anything about the client's input, output, and program. If the client interacts with only a single server, the client has to have some minimum quantum power, such as the ability of emitting randomly rotated single-qubit states or the ability of measuring states. If the client interacts with two servers who share Bell pairs but cannot communicate with each other, the client can be completely classical. For such a double-server scheme, two servers have to share clean Bell pairs, and therefore the entanglement distillation is necessary in a realistic noisy environment. In this Letter, we show that it is possible to perform entanglement distillation in the double-server scheme without degrading the security of blind quantum computing.

  18. Modeling and Optimization of M/G/1-Type Queueing Networks: An Efficient Sensitivity Analysis Approach

    Directory of Open Access Journals (Sweden)

    Liang Tang

    2010-01-01

    Full Text Available A mathematical model for M/G/1-type queueing networks with multiple user applications and limited resources is established. The goal is to develop a dynamic distributed algorithm for this model, which supports all data traffic as efficiently as possible and makes optimally fair decisions about how to minimize the network performance cost. An online policy gradient optimization algorithm based on a single sample path is provided to avoid suffering from a “curse of dimensionality”. The asymptotic convergence properties of this algorithm are proved. Numerical examples provide valuable insights for bridging mathematical theory with engineering practice.

  19. Universal Server - Informix al CILEA

    OpenAIRE

    Camnasio, Maurizio; Trombetta, Laura

    1998-01-01

    Viene presentato il nuovo prodotto Universal Server di INFORMIX installato al CILEA su macchina SUN Server ultra-2. Si tratta di un database relazionale ad oggetti capace di memorizzare e gestire in modo efficace dati alfanumerici, immagini, video, pagine Web e dati diversi definiti dall'utente, all'interno di un'unico repository.

  20. Server farms with setup costs

    NARCIS (Netherlands)

    Gandhi, A.; Harchol-Balter, M.; Adan, I.

    2010-01-01

    In this paper we consider server farms with a setup cost. This model is common in manufacturing systems and data centers, where there is a cost to turn servers on. Setup costs always take the form of a time delay, and sometimes there is additionally a power penalty, as in the case of data centers.

  1. First in line waiting times as a tool for analyzing queueing systems

    NARCIS (Netherlands)

    Koole, G.M.; Nielsen, B.; Nielsen, T.

    2012-01-01

    We introduce a new approach to modelling queueing systems where the priority or the routing of customers depends on the time the first customer has waited in the queue. This past waiting time of the first customer in line, W

  2. Universal fingerprinting chip server.

    Science.gov (United States)

    Casique-Almazán, Janet; Larios-Serrato, Violeta; Olguín-Ruíz, Gabriela Edith; Sánchez-Vallejo, Carlos Javier; Maldonado-Rodríguez, Rogelio; Méndez-Tenorio, Alfonso

    2012-01-01

    The Virtual Hybridization approach predicts the most probable hybridization sites across a target nucleic acid of known sequence, including both perfect and mismatched pairings. Potential hybridization sites, having a user-defined minimum number of bases that are paired with the oligonucleotide probe, are first identified. Then free energy values are evaluated for each potential hybridization site, and if it has a calculated free energy of equal or higher negative value than a user-defined free energy cut-off value, it is considered as a site of high probability of hybridization. The Universal Fingerprinting Chip Applications Server contains the software for visualizing predicted hybridization patterns, which yields a simulated hybridization fingerprint that can be compared with experimentally derived fingerprints or with a virtual fingerprint arising from a different sample. The database is available for free at http://bioinformatica.homelinux.org/UFCVH/

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

    Science.gov (United States)

    Nicol, David M.

    1988-01-01

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

  4. Research on a Queue Scheduling Algorithm in Wireless Communications Network

    Science.gov (United States)

    Yang, Wenchuan; Hu, Yuanmei; Zhou, Qiancai

    This paper proposes a protocol QS-CT, Queue Scheduling Mechanism based on Multiple Access in Ad hoc net work, which adds queue scheduling mechanism to RTS-CTS-DATA using multiple access protocol. By endowing different queues different scheduling mechanisms, it makes networks access to the channel much more fairly and effectively, and greatly enhances the performance. In order to observe the final performance of the network with QS-CT protocol, we simulate it and compare it with MACA/C-T without QS-CT protocol. Contrast to MACA/C-T, the simulation result shows that QS-CT has greatly improved the throughput, delay, rate of packets' loss and other key indicators.

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

    CERN Document Server

    Bhat, U Narayan

    2015-01-01

    This introductory textbook is designed for a one-semester course on queueing theory that does not require a course on stochastic processes as a prerequisite. By integrating the necessary background on stochastic processes with the analysis of models, the work provides a sound foundational introduction to the modeling and analysis of queueing systems for a wide interdisciplinary audience of students in mathematics, statistics, and applied disciplines such as computer science, operations research, and engineering. This edition includes additional topics in methodology and applications. Key features: • An introductory chapter including a historical account of the growth of queueing theory in more than 100 years. • A modeling-based approach with emphasis on identification of models. • Rigorous treatment of the foundations of basic models commonly used in applications with appropriate references for advanced topics. • Applications in manufacturing and, computer and communication systems. • A chapter on ...

  6. Strategic behavior and social outcomes in a bottleneck queue

    DEFF Research Database (Denmark)

    Breinbjerg, Jesper Breinbjerg; Sebald, Alexander Christopher; Østerdal, Lars Peter

    2016-01-01

    We theoretically and experimentally study the differential incentive effects of three well known queue disciplines in a strategic environment in which a bottleneck facility opens and impatient players decide when to arrive. For a class of three-player games, we derive equilibrium arrivals under...... the first-in-first-out (FIFO), last-in-first-out (LIFO), and service-in-random-order (SIRO) queue disciplines and compare these predictions to outcomes from a laboratory experiment. In line with our theoretical predictions, we find that people arrive with greater dispersion when participating under the LIFO...

  7. AUTOMATED TESTING OF OPC SERVERS

    CERN Document Server

    Farnham, B

    2011-01-01

    CERN relies on OPC Server implementations from 3rd party device vendors to provide a software interface to their respective hardware. Each time a vendor releases a new OPC Server version it is regression tested internally to verify that existing functionality has not been inadvertently broken during the process of adding new features. In addition bugs and problems must be communicated to the vendors in a reliable and portable way. This presentation covers the automated test approach used at CERN to cover both cases: Scripts are written in a domain specific language specifically created for describing OPC tests and executed by a custom software engine driving the OPC Server implementation.

  8. SQL Server 2014 development essentials

    CERN Document Server

    Masood-Al-Farooq, Basit A

    2014-01-01

    This book is an easy-to-follow, comprehensive guide that is full of hands-on examples, which you can follow to successfully design, build, and deploy mission-critical database applications with SQL Server 2014. If you are a database developer, architect, or administrator who wants to learn how to design, implement, and deliver a successful database solution with SQL Server 2014, then this book is for you. Existing users of Microsoft SQL Server will also benefit from this book as they will learn what's new in the latest version.

  9. Medical video server construction.

    Science.gov (United States)

    Dańda, Jacek; Juszkiewicz, Krzysztof; Leszczuk, Mikołaj; Loziak, Krzysztof; Papir, Zdzisław; Sikora, Marek; Watza, Rafal

    2003-01-01

    The paper discusses two implementation options for a Digital Video Library, a repository used for archiving, accessing, and browsing of video medical records. Two crucial issues to be decided on are a video compression format and a video streaming platform. The paper presents numerous decision factors that have to be taken into account. The compression formats being compared are DICOM as a format representative for medical applications, both MPEGs, and several new formats targeted for an IP networking. The comparison includes transmission rates supported, compression rates, and at least options for controlling a compression process. The second part of the paper presents the ISDN technique as a solution for provisioning of tele-consultation services between medical parties that are accessing resources uploaded to a digital video library. There are several backbone techniques (like corporate LANs/WANs, leased lines or even radio/satellite links) available, however, the availability of network resources for hospitals was the prevailing choice criterion pointing to ISDN solutions. Another way to provide access to the Digital Video Library is based on radio frequency domain solutions. The paper describes possibilities of both, wireless and cellular network's data transmission service to be used as a medical video server transport layer. For the cellular net-work based solution two communication techniques are used: Circuit Switched Data and Packet Switched Data.

  10. CERN Document Server (CDS): Introduction

    CERN Multimedia

    CERN. Geneva; Costa, Flavio

    2017-01-01

    A short online tutorial introducing the CERN Document Server (CDS). Basic functionality description, the notion of Revisions and the CDS test environment. Links: CDS Production environment CDS Test environment  

  11. ENERGY STAR Certified Enterprise Servers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 2.1 ENERGY STAR Program Requirements for Enterprise Servers that are effective as of...

  12. Large deviations for sojourn times in processor sharing queues.

    NARCIS (Netherlands)

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

    2006-01-01

    Abstract: This paper presents a large deviation analysis of the steady-state sojourn time distribution in the GI/G/1 PS queue. Logarithmic estimates are obtained under the assumption of the service time distribution having a light tail, thus supplementing recent results for the heavy-tailed setting.

  13. On Some Compound Random Variables Motivated by Bulk Queues

    Directory of Open Access Journals (Sweden)

    Romeo Meštrović

    2015-01-01

    Full Text Available We consider the distribution of the number of customers that arrive in an arbitrary bulk arrival queue system. Under certain conditions on the distributions of the time of arrival of an arriving group (Y(t and its size (X with respect to the considered bulk queue, we derive a general expression for the probability mass function of the random variable Q(t which expresses the number of customers that arrive in this bulk queue during any considered period t. Notice that Q(t can be considered as a well-known compound random variable. Using this expression, without the use of generating function, we establish the expressions for probability mass function for some compound distributions Q(t concerning certain pairs (Y(t,X of discrete random variables which play an important role in application of batch arrival queues which have a wide range of applications in different forms of transportation. In particular, we consider the cases when Y(t and/or X are some of the following distributions: Poisson, shifted-Poisson, geometrical, or uniform random variable.

  14. Simulated queues in dynamic situations | Ojarikre | Journal of the ...

    African Journals Online (AJOL)

    Discrete event simulation of dynamic situation of queuing systems has been carried out using the next-event simulated time procedure for the Monte Carlo and Area ... The dynamic nature of the periods will change the status of a number of random variables like the length of each queue, the time delay of each customer and ...

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

    Directory of Open Access Journals (Sweden)

    Vladimiras Dolgopolovas

    2014-01-01

    Full Text Available In this paper, we present the methodology for the introduction to scientific computing based on model-centered learning. We propose multiphase queueing systems as a basis for learning objects. We use Python and parallel programming for implementing the models and present the computer code and results of stochastic simulations.

  16. Overflow behavoir in queues with many long-tailed inputs

    NARCIS (Netherlands)

    M.R.H. Mandjes (Michel); S.C. Borst (Sem)

    1999-01-01

    textabstractWe consider a fluid queue fed by a superposition of $n$ homogeneous on-off sources with generally distributed on- and off-periods. We scale buffer space $B$ and link rate $C$ by $n$, such that we get $nb$ and $nc$, respectively. Then we let $n$ grow large. In this regime, the overflow

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  18. Queueing and Service Patterns in a University Teaching Hospital FO

    African Journals Online (AJOL)

    acer

    ABSTRACT: Analysis of queueing and service times is essential for designing effective congestion control at a service point. The objective of this is to be able to offer satisfactory service to waiting customers with minimum delay. In this study, using University of Abuja Teaching Hospital as a case study, we compared the ...

  19. Multi-Resource Fair Queueing for Packet Processing

    Science.gov (United States)

    2012-06-19

    flows were active [24]. This memoryless property is key to guaranteeing that flows cannot be starved in a work- conserving system. We design a new...2011. [17] S. J. Golestani. A self-clocked fair queueing scheme for broadband applications. In INFOCOM, pages 636–646, 1994. [18] P. Goyal, H. Vin

  20. Predicting clinical image delivery time by monitoring PACS queue behavior.

    Science.gov (United States)

    King, Nelson E; Documet, Jorge; Liu, Brent

    2006-01-01

    The expectation of rapid image retrieval from PACS users contributes to increased information technology (IT) infrastructure investments to increase performance as well as continuing demands upon PACS administrators to respond to "slow" system performance. The ability to provide predicted delivery times to a PACS user may curb user expectations for "fastest" response especially during peak hours. This, in turn, could result in a PACS infrastructure tailored to more realistic performance demands. A PACS with a stand-alone architecture under peak load typically holds study requests in a queue until the DICOM C-Move command can take place. We investigate the contents of a stand-alone architecture PACS RetrieveSend queue and identified parameters and behaviors that enable a more accurate prediction of delivery time. A prediction algorithm for studies delayed in a stand-alone PACS queue can be extendible to other potential bottlenecks such as long-term storage archives. Implications of a queue monitor in other PACS architectures are also discussed.

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

    African Journals Online (AJOL)

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

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

    DEFF Research Database (Denmark)

    Iversen, Villy Bæk; Staalhagen, Lars

    1999-01-01

    The well-known formula for the waiting time distribution of M/D/1 queueing systems is numerically unsuitable when the load is close to 1.0 and/or the results for a large waiting time are required. An algorithm for any load and waiting time is presented, based on the state probabilities of M/D/1...

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

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 6. Algorithms - Data Structures: Lists, Queues, Stacks and Arrays. R K Shyamasundar ... Author Affiliations. R K Shyamasundar1. Computer Science Group, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India ...

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

    NARCIS (Netherlands)

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

    2001-01-01

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

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

    NARCIS (Netherlands)

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

    2003-01-01

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

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

    Indian Academy of Sciences (India)

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

  7. Efficient Simulation of Population Overflow in Parallel Queues

    NARCIS (Netherlands)

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

    2006-01-01

    In this paper we propose a state-dependent importance sampling heuristic to estimate the probability of population overflow in networks of parallel queues. This heuristic approximates the “optimal��? state-dependent change of measure without the need for dif��?cult mathematical analysis or costly

  8. Analisis Perbandingan Unjuk Kerja Sistem Penyeimbang Beban Web Server dengan HAProxy dan Pound Links

    Directory of Open Access Journals (Sweden)

    Dite Ardian

    2013-04-01

    Full Text Available The development of internet technology has many organizations that expanded service website. Initially used single web server that is accessible to everyone through the Internet, but when the number of users that access the web server is very much the traffic load to the web server and the web server anyway. It is necessary for the optimization of web servers to cope with the overload received by the web server when traffic is high. Methodology of this final project research include the study of literature, system design, and testing of the system. Methods from the literature reference books related as well as from several sources the internet. The design of this thesis uses Haproxy and Pound Links as a load balancing web server. The end of this reaserch is testing the network system, where the system will be tested this stage so as to create a web server system that is reliable and safe. The result is a web server system that can be accessed by many user simultaneously rapidly as load balancing Haproxy and Pound Links system which is set up as front-end web server performance so as to create a web server that has performance and high availability.

  9. Mastering Citrix XenServer

    CERN Document Server

    Reed, Martez

    2014-01-01

    If you are an administrator who is looking to gain a greater understanding of how to design and implement a virtualization solution based on Citrix® XenServer®, then this book is for you. The book will serve as an excellent resource for those who are already familiar with other virtualization platforms, such as Microsoft Hyper-V or VMware vSphere.The book assumes that you have a good working knowledge of servers, networking, and storage technologies.

  10. Building server capabilities in China

    DEFF Research Database (Denmark)

    Adeyemi, Oluseyi; Slepniov, Dmitrij; Wæhrens, Brian Vejrum

    2012-01-01

    The purpose of this paper is to further our understanding of multinational companies building server capabilities in China. The paper is based on the cases of two western companies with operations in China. The findings highlight a number of common patterns in the 1) managerial challenges related...... to the development of server capabilities at offshore sites, and 2) means of how these challenges can be handled....

  11. Windows Server 2012 R2 administrator cookbook

    CERN Document Server

    Krause, Jordan

    2015-01-01

    This book is intended for system administrators and IT professionals with experience in Windows Server 2008 or Windows Server 2012 environments who are looking to acquire the skills and knowledge necessary to manage and maintain the core infrastructure required for a Windows Server 2012 and Windows Server 2012 R2 environment.

  12. Efficient Redundancy Techniques in Cloud and Desktop Grid Systems using MAP/G/c-type Queues

    Science.gov (United States)

    Chakravarthy, Srinivas R.; Rumyantsev, Alexander

    2018-03-01

    Cloud computing is continuing to prove its flexibility and versatility in helping industries and businesses as well as academia as a way of providing needed computing capacity. As an important alternative to cloud computing, desktop grids allow to utilize the idle computer resources of an enterprise/community by means of distributed computing system, providing a more secure and controllable environment with lower operational expenses. Further, both cloud computing and desktop grids are meant to optimize limited resources and at the same time to decrease the expected latency for users. The crucial parameter for optimization both in cloud computing and in desktop grids is the level of redundancy (replication) for service requests/workunits. In this paper we study the optimal replication policies by considering three variations of Fork-Join systems in the context of a multi-server queueing system with a versatile point process for the arrivals. For services we consider phase type distributions as well as shifted exponential and Weibull. We use both analytical and simulation approach in our analysis and report some interesting qualitative results.

  13. Remote data access, analysis and visualization with the Live Access Server

    Science.gov (United States)

    Callahan, J.; Hankin, S.

    2006-05-01

    The Live Access Server (LAS) is a highly configurable Web server designed to provide flexible access to geo- referenced scientific data. It can present distributed data sets as a unified virtual data base through the use of OPeNDAP networking. This talk will describe the configurable features of LAS that allow data providers to unify access to multiple types of data in a single interface and provide thematic data servers from distributed data sources.

  14. QlikView Server and Publisher

    CERN Document Server

    Redmond, Stephen

    2014-01-01

    This is a comprehensive guide with a step-by-step approach that enables you to host and manage servers using QlikView Server and QlikView Publisher.If you are a server administrator wanting to learn about how to deploy QlikView Server for server management,analysis and testing, and QlikView Publisher for publishing of business content then this is the perfect book for you. No prior experience with QlikView is expected.

  15. Reproductive queue without overt conflict in the primitively eusocial wasp Ropalidia marginata.

    Science.gov (United States)

    Bang, Alok; Gadagkar, Raghavendra

    2012-09-04

    Colonies of the primitively eusocial wasp Ropalidia marginata consist of a single egg layer (queen) and a number of non-egg-laying workers. Although the queen is a docile individual, not at the top of the behavioral dominance hierarchy of the colony, she maintains complete reproductive monopoly. If the queen is lost or removed, one and only one of the workers [potential queen (PQ)] becomes hyperaggressive and will become the next queen of the colony. The PQ is almost never challenged because she first becomes hyperaggressive and then gradually loses her aggression, develops her ovaries, and starts laying eggs. Although we are unable to identify the PQ when the queen is present, she appears to be a "cryptic heir designate." Here, we show that there is not just one heir designate but a long reproductive queue and that PQs take over the role of egg-laying, successively, without overt conflict, as the queen or previous PQs are removed. The dominance rank of an individual is not a significant predictor of its position in the succession hierarchy. The age of an individual is a significant predictor, but it is not a perfect predictor because PQs often bypass older individuals to become successors. We suggest that such a predesignated reproductive queue that is implemented without overt conflict is adaptive in the tropics, where conspecific usurpers from outside the colony, which can take advantage of the anarchy prevailing in a queenless colony and invade it, are likely to be present throughout the year.

  16. Getting started with Microsoft Lync server 2013

    CERN Document Server

    Volpe, Fabrizio

    2013-01-01

    This book has a practical approach with a lot of step-by-step guides and explanations as to where and why we're doing the various operations.Getting Started with Microsoft Lync Server 2013 is a starting point for system administrators, IT pros, unified communication technicians, and decision makers in companies or in the consultancy business. For people who have never managed Lync (or a U.C. product), the book will guide you through the basic concepts and mistakes. If you are already managing a Lync deployment you will find important explanations and ideas put together in a single text. If you

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

    Science.gov (United States)

    Fernandez, Roberto M; Mors, Marie Louise

    2008-12-01

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

  18. Group-oriented coordination models for distributed client-server computing

    Science.gov (United States)

    Adler, Richard M.; Hughes, Craig S.

    1994-01-01

    This paper describes group-oriented control models for distributed client-server interactions. These models transparently coordinate requests for services that involve multiple servers, such as queries across distributed databases. Specific capabilities include: decomposing and replicating client requests; dispatching request subtasks or copies to independent, networked servers; and combining server results into a single response for the client. The control models were implemented by combining request broker and process group technologies with an object-oriented communication middleware tool. The models are illustrated in the context of a distributed operations support application for space-based systems.

  19. Conservative parallel simulation of priority class queueing networks

    Science.gov (United States)

    Nicol, David

    1992-01-01

    A conservative synchronization protocol is described for the parallel simulation of queueing networks having C job priority classes, where a job's class is fixed. This problem has long vexed designers of conservative synchronization protocols because of its seemingly poor ability to compute lookahead: the time of the next departure. For, a job in service having low priority can be preempted at any time by an arrival having higher priority and an arbitrarily small service time. The solution is to skew the event generation activity so that the events for higher priority jobs are generated farther ahead in simulated time than lower priority jobs. Thus, when a lower priority job enters service for the first time, all the higher priority jobs that may preempt it are already known and the job's departure time can be exactly predicted. Finally, the protocol was analyzed and it was demonstrated that good performance can be expected on the simulation of large queueing networks.

  20. 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...

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

    Directory of Open Access Journals (Sweden)

    Lan Li

    2003-12-01

    Full Text Available This paper proposes an adaptive queue management scheme (adaptive RED to improve Random Early Detection (RED on restraining non-responsive flows. Due to a lack of flow control mechanism, non-responsive flows can starve responsive flows for buffer and bandwidth at the gateway. In order to solve the disproportionate resource problem, RED framework is modified in this way: on detecting when the non-responsive flows starve the queue, packet-drop intensity (Max_p in RED can be adaptively adjusted to curb non-responsive flows for resource fair-sharing, such as buffer and bandwidth fair-sharing. Based on detection of traffic behaviors, intentionally restraining nonresponsive flows is to increase the throughput and decrease the drop rate of responsive flows. Our experimental results based on adaptive RED shows that the enhancement of responsive traffic and the better sharing of buffer and bandwidth can be achieved under a variety of traffic scenarios.

  2. GeoServer beginner's guide

    CERN Document Server

    Youngblood, Brian

    2013-01-01

    Step-by-step instructions are included and the needs of a beginner are totally satisfied by the book. The book consists of plenty of examples with accompanying screenshots and code for an easy learning curve. You are a web developer with knowledge of server side scripting, and have experience with installing applications on the server. You have a desire to want more than Google maps, by offering dynamically built maps on your site with your latest geospatial data stored in MySQL, PostGIS, MsSQL or Oracle. If this is the case, this book is meant for you.

  3. Professional Team Foundation Server 2010

    CERN Document Server

    Blankenship, Ed; Holliday, Grant; Keller, Brian

    2011-01-01

    Authoritative guide to TFS 2010 from a dream team of Microsoft insiders and MVPs!Microsoft Visual Studio Team Foundation Server (TFS) has evolved until it is now an essential tool for Microsoft?s Application Lifestyle Management suite of productivity tools, enabling collaboration within and among software development teams. By 2011, TFS will replace Microsoft?s leading source control system, VisualSourceSafe, resulting in an even greater demand for information about it. Professional Team Foundation Server 2010, written by an accomplished team of Microsoft insiders and Microsoft MVPs, provides

  4. Professional Team Foundation Server 2012

    CERN Document Server

    Blankenship, Ed; Holliday, Grant; Keller, Brian

    2012-01-01

    A comprehensive guide to using Microsoft Team Foundation Server 2012 Team Foundation Server has become the leading Microsoft productivity tool for software management, and this book covers what developers need to know to use it effectively. Fully revised for the new features of TFS 2012, it provides developers and software project managers with step-by-step instructions and even assists those who are studying for the TFS 2012 certification exam. You'll find a broad overview of TFS, thorough coverage of core functions, a look at extensibility options, and more, written by Microsoft ins

  5. MQCC: Maximum Queue Congestion Control for Multipath Networks with Blockage

    Science.gov (United States)

    2015-10-19

    loss or round trip time (RTT)) and updates the transmission rate of each source to avoid network congestion. This allows us to design a congestion...maximum measured queue lengths and round trip time (RTT) measurements to prevent congestion. We present each phase of the congestion controller...7] L Brakmo and L Peterson, “Tcp vegas: End to end congestion avoidance on a global internet,” IEEE Journal on Selected Areas in Communica- tions, vol

  6. Do Informal Workers Queue For Formal Jobs in Brazil ?

    OpenAIRE

    Fábio Veras Soares

    2004-01-01

    This paper investigates the existence of a job queue for formal (registered) jobs in the Brazilian labour market in an endogenous switching regression framework. This approach aims at correctly specifying the allocation process in the presence of queuing and getting unbiased wage equation estimates in order evaluate the role of wage differential between formal and informal sector in determining sector allocation. We estimate three types of bivariate probit specifications in order to evaluate ...

  7. Diagonal queue medical image steganography with Rabin cryptosystem.

    Science.gov (United States)

    Jain, Mamta; Lenka, Saroj Kumar

    2016-03-01

    The main purpose of this work is to provide a novel and efficient method to the image steganography area of research in the field of biomedical, so that the security can be given to the very precious and confidential sensitive data of the patient and at the same time with the implication of the highly reliable algorithms will explode the high security to the precious brain information from the intruders. The patient information such as patient medical records with personal identification information of patients can be stored in both storage and transmission. This paper describes a novel methodology for hiding medical records like HIV reports, baby girl fetus, and patient's identity information inside their Brain disease medical image files viz. scan image or MRI image using the notion of obscurity with respect to a diagonal queue least significant bit substitution. Data structure queue plays a dynamic role in resource sharing between multiple communication parties and when secret medical data are transferred asynchronously (secret medical data not necessarily received at the same rate they were sent). Rabin cryptosystem is used for secret medical data writing, since it is computationally secure against a chosen-plaintext attack and shows the difficulty of integer factoring. The outcome of the cryptosystem is organized in various blocks and equally distributed sub-blocks. In steganography process, various Brain disease cover images are organized into various blocks of diagonal queues. The secret cipher blocks and sub-blocks are assigned dynamically to selected diagonal queues for embedding. The receiver gets four values of medical data plaintext corresponding to one ciphertext, so only authorized receiver can identify the correct medical data. Performance analysis was conducted using MSE, PSNR, maximum embedding capacity as well as by histogram analysis between various Brain disease stego and cover images.

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

    Index Scriptorium Estoniae

    Soomre, Maria-Kristiina, 1978-

    2010-01-01

    Tallinna Lauluväljakul veebruaris 2010 olnud töötute järjekorrast, kus 5000-st said alternatiivse töö reisisaatjatena 400. Keskerakonna kampaaniatest, mida võib vaadata sotsiaalse kunsti kontekstis. Sügisel 2010 Tallinna Kunstihoone juures korraldatud kunstiprojektist "Art Queue 100x100 EEK", millega sooviti tõmmata tähelepanu kunstiinstitutsioonile. Seoses kunstiga tekkinud järjekordadest, masside valmidusest kampaania korras rünnata kunsti

  9. Implementing Citrix XenServer Quickstarter

    CERN Document Server

    Ahmed, Gohar

    2013-01-01

    Implementing Citrix XenServer Quick Starter is a practical, hands-on guide that will help you get started with the Citrix XenServer Virtualization technology with easy-to-follow instructions.Implementing Citrix XenServer Quick Starter is for system administrators who have little to no information on virtualization and specifically Citrix XenServer Virtualization. If you're managing a lot of physical servers and are tired of installing, deploying, updating, and managing physical machines on a daily basis over and over again, then you should probably explore your option of XenServer Virtualizati

  10. Beginning Microsoft SQL Server 2012 Programming

    CERN Document Server

    Atkinson, Paul

    2012-01-01

    Get up to speed on the extensive changes to the newest release of Microsoft SQL Server The 2012 release of Microsoft SQL Server changes how you develop applications for SQL Server. With this comprehensive resource, SQL Server authority Robert Vieira presents the fundamentals of database design and SQL concepts, and then shows you how to apply these concepts using the updated SQL Server. Publishing time and date with the 2012 release, Beginning Microsoft SQL Server 2012 Programming begins with a quick overview of database design basics and the SQL query language and then quickly proceeds to sho

  11. Learning SQL Server Reporting Services 2012

    CERN Document Server

    Krishnaswamy, Jayaram

    2013-01-01

    The book is packed with clear instructions and plenty of screenshots, providing all the support and guidance you will need as you begin to generate reports with SQL Server 2012 Reporting Services.This book is for those who are new to SQL Server Reporting Services 2012 and aspiring to create and deploy cutting edge reports. This book is for report developers, report authors, ad-hoc report authors and model developers, and Report Server and SharePoint Server Integrated Report Server administrators. Minimal knowledge of SQL Server is assumed and SharePoint experience would be helpful.

  12. Open client/server computing and middleware

    CERN Document Server

    Simon, Alan R

    2014-01-01

    Open Client/Server Computing and Middleware provides a tutorial-oriented overview of open client/server development environments and how client/server computing is being done.This book analyzes an in-depth set of case studies about two different open client/server development environments-Microsoft Windows and UNIX, describing the architectures, various product components, and how these environments interrelate. Topics include the open systems and client/server computing, next-generation client/server architectures, principles of middleware, and overview of ProtoGen+. The ViewPaint environment

  13. Usage of Thin-Client/Server Architecture in Computer Aided Education

    Science.gov (United States)

    Cimen, Caghan; Kavurucu, Yusuf; Aydin, Halit

    2014-01-01

    With the advances of technology, thin-client/server architecture has become popular in multi-user/single network environments. Thin-client is a user terminal in which the user can login to a domain and run programs by connecting to a remote server. Recent developments in network and hardware technologies (cloud computing, virtualization, etc.)…

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

    Science.gov (United States)

    Peden, Jeffery H.

    1990-01-01

    Currently the end-to-end delay characteristics of very high speed local area networks are not well understood. The transmission speed of computer networks is increasing, and local area networks especially are finding increasing use in real time systems. Ring networks operation is generally well understood for both token rings and slotted rings. There is, however, a severe lack of queueing models for high layer operation. There are several factors which contribute to the processing delay of a packet, as opposed to the transmission delay, e.g., packet priority, its length, the user load, the processor load, the use of priority preemption, the use of preemption at packet reception, the number of processors, the number of protocol processing layers, the speed of each processor, and queue length limitations. Currently existing medium access queueing models are extended by adding modeling techniques which will handle exhaustive limited service both with and without priority traffic, and modeling capabilities are extended into the upper layers of the OSI model. Some of the model are parameterized solution methods, since it is shown that certain models do not exist as parameterized solutions, but rather as solution methods.

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

    Science.gov (United States)

    Takagi, Hideaki; Kanai, Yuta; Misue, Kazuo

    2016-03-03

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

  16. Exclusive queueing model including the choice of service windows

    Science.gov (United States)

    Tanaka, Masahiro; Yanagisawa, Daichi; Nishinari, Katsuhiro

    2018-01-01

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

  17. On a tandem queue with batch service and its applications in wireless sensor networks

    NARCIS (Netherlands)

    Mitici, Michaela; Goseling, Jasper; van Ommeren, Jan C.W.; de Graaf, Maurits; Boucherie, Richard

    2017-01-01

    We present a tandem network of queues 0, …, s -1. Customers arrive at queue 0 according to a Poisson process with rate λ. There are s independent batch service processes at exponential rates μ0, …, μs−1. Service process i , i = 0, … , s -1, at rate μi is such that all customers of all queues 0, …, i

  18. Team Foundation Server 2013 customization

    CERN Document Server

    Beeming, Gordon

    2014-01-01

    This book utilizes a tutorial based approach, focused on the practical customization of key features of the Team Foundation Server for collaborative enterprise software projects.This practical guide is intended for those who want to extend TFS. This book is for intermediate users who have an understanding of TFS, and basic coding skills will be required for the more complex customizations.

  19. Client-Server Password Recovery

    NARCIS (Netherlands)

    Chmielewski, L.; Hoepman, J.H.; Rossum, P. van

    2009-01-01

    Human memory is not perfect – people constantly memorize new facts and forget old ones. One example is forgetting a password, a common problem raised at IT help desks. We present several protocols that allow a user to automatically recover a password from a server using partial knowledge of the

  20. Client-server password recovery

    NARCIS (Netherlands)

    Chmielewski, Ł.; Hoepman, J.H.; Rossum, P. van

    2009-01-01

    Human memory is not perfect - people constantly memorize new facts and forget old ones. One example is forgetting a password, a common problem raised at IT help desks. We present several protocols that allow a user to automatically recover a password from a server using partial knowledge of the

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

    Science.gov (United States)

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

    2017-11-01

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

  2. Web Server Configuration for an Academic Intranet

    National Research Council Canada - National Science Library

    Baltzis, Stamatios

    2000-01-01

    .... One of the factors that boosted this ability was the evolution of the Web Servers. Using the web server technology man can be connected and exchange information with the most remote places all over the...

  3. Implementation of SRPT Scheduling in Web Servers

    National Research Council Canada - National Science Library

    Harchol-Balter, Mor

    2000-01-01

    .... Experiments use the Linux operating system and the Flash web server. All experiments are repeated under a range of server loads and under both trace-based workloads and those generated by a Web workload generator...

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

    KAUST Repository

    Showail, Ahmad

    2014-08-17

    Choosing the right buffer size in Wi-Fi networks is challenging due to the dynamic nature of the wireless environment. Over buffering or \\'bufferbloat\\' may produce unacceptable end-to-end delays, while static small buffers may limit the performance gains that can be achieved with various 802.11n enhancements, such as frame aggregation. We propose WQM, a queue management scheme customized for wireless networks. WQM adapts the buffer size based on measured link characteristics and network load. Furthermore, it accounts for aggregate length when deciding about the optimal buffer size. We implement WQM on Linux and evaluate it on a wireless testbed. WQM reduces the end-to-end delay by up to 8x compared to Linux default buffer size, and 2x compared to CoDel, the state-of-the-art bufferbloat solution, while achieving comparable network goodput. Further, WQM improves fairness as it limits the ability of a single flow to saturate the buffer.

  5. A polling model with an autonomous server

    NARCIS (Netherlands)

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

    Polling models are used as an analytical performance tool in several application areas. In these models, the focus often is on controlling the operation of the server as to optimize some performance measure. For several applications, controlling the server is not an issue as the server moves

  6. NRSAS: Nuclear Receptor Structure Analysis Servers.

    NARCIS (Netherlands)

    Bettler, E.J.M.; Krause, R.; Horn, F.; Vriend, G.

    2003-01-01

    We present a coherent series of servers that can perform a large number of structure analyses on nuclear hormone receptors. These servers are part of the NucleaRDB project, which provides a powerful information system for nuclear hormone receptors. The computations performed by the servers include

  7. OPeNDAP servers like Hyrax and TDS can easily support common single-sign-on authentication protocols using the Apache httpd and related software; adding support for these protocols to clients can be more challenging

    Science.gov (United States)

    Gallagher, J. H. R.; Potter, N.; Evans, B. J. K.

    2016-12-01

    OPeNDAP, in conjunction with the Australian National University, documented the installation process needed to add authentication to OPeNDAP-enabled data servers (Hyrax, TDS, etc.) and examined 13 OPeNDAP clients to determine how best to add authentication using LDAP, Shibboleth and OAuth2 (we used NASA's URS). We settled on a server configuration (architecture) that uses the Apache web server and a collection of open-source modules to perform the authentication and authorization actions. This is not the only way to accomplish those goals, but using Apache represents a good balance between functionality, leveraging existing work that has been well vetted and includes support for a wide variety of web services, include those that depend on a servlet engine such as tomcat (which both Hyrax and TDS do). Or work shows how LDAP, OAuth2 and Shibboleth can all be accommodated using this readily available software stack. Also important is that the Apache software is very widely used and is fairly robust - extremely important for security software components. In order to make use of a server requiring authentication, clients must support the authentication process. Because HTTP has included authentication for well over a decade, and because HTTP/HTTPS can be used by simply linking programs with a library, both the LDAP and OAuth2/URS authentication schemes have almost universal support within the OPeNDAP client base. The clients, i.e. the HTTP client libraries they employ, understand how to submit the credentials to the correct server when confronted by an HTTP/S Unauthorized (401) response. Interestingly OAuth2 can achieve it's SSO objectives while relying entirely on normative HTTP transport. All 13 of the clients examined worked.The situation with Shibboleth is different. While Shibboleth does use HTTP, it also requires the client to either scrape a web page or support the SAML2.0 ECP profile, which, for programmatic clients, means using SOAP messages. Since working with

  8. Adventures in the evolution of a high-bandwidth network for central servers

    International Nuclear Information System (INIS)

    Swartz, K.L.; Cottrell, L.; Dart, M.

    1994-08-01

    In a small network, clients and servers may all be connected to a single Ethernet without significant performance concerns. As the number of clients on a network grows, the necessity of splitting the network into multiple sub-networks, each with a manageable number of clients, becomes clear. Less obvious is what to do with the servers. Group file servers on subnets and multihomed servers offer only partial solutions -- many other types of servers do not lend themselves to a decentralized model, and tend to collect on another, well-connected but overloaded Ethernet. The higher speed of FDDI seems to offer an easy solution, but in practice both expense and interoperability problems render FDDI a poor choice. Ethernet switches appear to permit cheaper and more reliable networking to the servers while providing an aggregate network bandwidth greater than a simple Ethernet. This paper studies the evolution of the server networks at SLAC. Difficulties encountered in the deployment of FDDI are described, as are the tools and techniques used to characterize the traffic patterns on the server network. Performance of Ethernet, FDDI, and switched Ethernet networks is analyzed, as are reliability and maintainability issues for these alternatives. The motivations for re-designing the SLAC general server network to use a switched Ethernet instead of FDDI are described, as are the reasons for choosing FDDI for the farm and firewall networks at SLAC. Guidelines are developed which may help in making this choice for other networks

  9. Professional Microsoft SQL Server 2012 Administration

    CERN Document Server

    Jorgensen, Adam; LoForte, Ross; Knight, Brian

    2012-01-01

    An essential how-to guide for experienced DBAs on the most significant product release since 2005! Microsoft SQL Server 2012 will have major changes throughout the SQL Server and will impact how DBAs administer the database. With this book, a team of well-known SQL Server experts introduces the many new features of the most recent version of SQL Server and deciphers how these changes will affect the methods that administrators have been using for years. Loaded with unique tips, tricks, and workarounds for handling the most difficult SQL Server admin issues, this how-to guide deciphers topics s

  10. Mastering Microsoft Windows Server 2008 R2

    CERN Document Server

    Minasi, Mark; Finn, Aidan

    2010-01-01

    The one book you absolutely need to get up and running with Windows Server 2008 R2. One of the world's leading Windows authorities and top-selling author Mark Minasi explores every nook and cranny of the latest version of Microsoft's flagship network operating system, Windows Server 2008 R2, giving you the most in-depth coverage in any book on the market.: Focuses on Windows Windows Server 2008 R2, the newest version of Microsoft's Windows' server line of operating system, and the ideal server for new Windows 7 clients; Author Mark Minasi is one of the world's leading Windows authorities and h

  11. PERANCANGAN APLIKASI FRONTDESK SERVER ASSISTANT (FOSA

    Directory of Open Access Journals (Sweden)

    Dahlan Abdullah

    2014-01-01

    Full Text Available Perkembangan teknologi informasi yang sangat pesat turut memajukan media komunikasi sebagai media penyampaian informasi dari suatu tempat ke tempat lainnya, sehingga memudahkan orang dalam mengakses media komunikasi.Dalam faktor keamanan ini biasanya perusahaan menempatkan administrator untuk menjaga tetapi fungsi administrator tentunya akan terbatas waktunya, saat jam kerja.perancangan aplikasi yang melayani para administrator server dalam hal menjaga dan memelihara kestabilan server  tanpa membutuhkan keahlian tertentu dalam  memanfaatkan aplikasi tersebut oleh penulis system tersebut diberi nama Frontdesk Server Assistant (Fosa. Kata kunci : Server, Client, Administrator, Frontdeks Server Assistan (Fosa

  12. CERN servers go to Mexico

    CERN Multimedia

    Stefania Pandolfi

    2015-01-01

    On Wednesday, 26 August, 384 servers from the CERN Computing Centre were donated to the Faculty of Science in Physics and Mathematics (FCFM) and the Mesoamerican Centre for Theoretical Physics (MCTP) at the University of Chiapas, Mexico.   CERN’s Director-General, Rolf Heuer, met the Mexican representatives in an official ceremony in Building 133, where the servers were prepared for shipment. From left to right: Frédéric Hemmer, CERN IT Department Head; Raúl Heredia Acosta, Deputy Permanent Representative of Mexico to the United Nations and International Organizations in Geneva; Jorge Castro-Valle Kuehne, Ambassador of Mexico to the Swiss Confederation and the Principality of Liechtenstein; Rolf Heuer, CERN Director-General; Luis Roberto Flores Castillo, President of the Swiss Chapter of the Global Network of Qualified Mexicans Abroad; Virginia Romero Tellez, Coordinator of Institutional Relations of the Swiss Chapter of the Global Network of Qualified Me...

  13. PENGEMBANGAN ANTIVIRUS BERBASIS CLIENT SERVER

    Directory of Open Access Journals (Sweden)

    Richki Hardi

    2015-07-01

    Full Text Available The era of globalization is included era where the komputer virus has been growing rapidly, not only of mere academic research but has become a common problem for komputer users in the world. The effect of this loss is increasingly becoming the widespread use of the Internet as a global communication line between komputer users around the world, based on the results of the survey CSI / FB. Along with the progress, komputer viruses undergo some evolution in shape, characteristics and distribution medium such as Worms, Spyware Trojan horse and program Malcodelain. Through the development of server-based antivirus clien then the user can easily determine the behavior of viruses and worms, knowing what part of an operating system that is being attacked by viruses and worms, making itself a development of network-based antivirus client server and can also be relied upon as an engine fast and reliable scanner to recognize the virus and saving in memory management.

  14. Matrix-Geometric Solution for Two Node Tandem Queueing Systems with Phase-Type Servers Subject to Blocking and Failures

    National Research Council Canada - National Science Library

    Guen, Levent; Makowski, Armand M

    1987-01-01

    .... The corresponding rate matrix is given explicitly in terms of the modA parameters and the resulting closed-form expression provides the basis for an efficient calculation of the invariant probability vector...

  15. Client-Server Password Recovery

    Science.gov (United States)

    Chmielewski, Łukasz; Hoepman, Jaap-Henk; van Rossum, Peter

    Human memory is not perfect - people constantly memorize new facts and forget old ones. One example is forgetting a password, a common problem raised at IT help desks. We present several protocols that allow a user to automatically recover a password from a server using partial knowledge of the password. These protocols can be easily adapted to the personal entropy setting [7], where a user can recover a password only if he can answer a large enough subset of personal questions.

  16. PostgreSQL server programming

    CERN Document Server

    Krosing, Hannu

    2013-01-01

    This practical guide leads you through numerous aspects of working with PostgreSQL. Step by step examples allow you to easily set up and extend PostgreSQL. ""PostgreSQL Server Programming"" is for moderate to advanced PostgreSQL database professionals. To get the best understanding of this book, you should have general experience in writing SQL, a basic idea of query tuning, and some coding experience in a language of your choice.

  17. Creating Large Scale Database Servers

    Energy Technology Data Exchange (ETDEWEB)

    Becla, Jacek

    2001-12-14

    The BaBar experiment at the Stanford Linear Accelerator Center (SLAC) is designed to perform a high precision investigation of the decays of the B-meson produced from electron-positron interactions. The experiment, started in May 1999, will generate approximately 300TB/year of data for 10 years. All of the data will reside in Objectivity databases accessible via the Advanced Multi-threaded Server (AMS). To date, over 70TB of data have been placed in Objectivity/DB, making it one of the largest databases in the world. Providing access to such a large quantity of data through a database server is a daunting task. A full-scale testbed environment had to be developed to tune various software parameters and a fundamental change had to occur in the AMS architecture to allow it to scale past several hundred terabytes of data. Additionally, several protocol extensions had to be implemented to provide practical access to large quantities of data. This paper will describe the design of the database and the changes that we needed to make in the AMS for scalability reasons and how the lessons we learned would be applicable to virtually any kind of database server seeking to operate in the Petabyte region.

  18. Creating Large Scale Database Servers

    International Nuclear Information System (INIS)

    Becla, Jacek

    2001-01-01

    The BaBar experiment at the Stanford Linear Accelerator Center (SLAC) is designed to perform a high precision investigation of the decays of the B-meson produced from electron-positron interactions. The experiment, started in May 1999, will generate approximately 300TB/year of data for 10 years. All of the data will reside in Objectivity databases accessible via the Advanced Multi-threaded Server (AMS). To date, over 70TB of data have been placed in Objectivity/DB, making it one of the largest databases in the world. Providing access to such a large quantity of data through a database server is a daunting task. A full-scale testbed environment had to be developed to tune various software parameters and a fundamental change had to occur in the AMS architecture to allow it to scale past several hundred terabytes of data. Additionally, several protocol extensions had to be implemented to provide practical access to large quantities of data. This paper will describe the design of the database and the changes that we needed to make in the AMS for scalability reasons and how the lessons we learned would be applicable to virtually any kind of database server seeking to operate in the Petabyte region

  19. On a tandem queue with batch service and its applications in wireless sensor networks

    NARCIS (Netherlands)

    Mitici, M.A.; Goseling, Jasper; van Ommeren, Jan Kees; de Graaf, Maurits; Boucherie, Richard J.

    2017-01-01

    We present a tandem network of queues 0 , ⋯ , s- 1. Customers arrive at queue 0 according to a Poisson process with rate λ. There are s independent batch service processes at exponential rates μ0, ⋯ , μs - 1. Service process i, i= 0 , ⋯ , s- 1 , at rate

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

    NARCIS (Netherlands)

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

    2006-01-01

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

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

    CERN Document Server

    Neely, Michael

    2010-01-01

    This text presents a modern theory of analysis, control, and optimization for dynamic networks. Mathematical techniques of Lyapunov drift and Lyapunov optimization are developed and shown to enable constrained optimization of time averages in general stochastic systems. The focus is on communication and queueing systems, including wireless networks with time-varying channels, mobility, and randomly arriving traffic. A simple drift-plus-penalty framework is used to optimize time averages such as throughput, throughput-utility, power, and distortion. Explicit performance-delay tradeoffs are prov

  2. Studying Pensions Funds Through an Infinite Servers Nodes Network: A Theoretical Problem

    International Nuclear Information System (INIS)

    Ferreira, M A M; Andrade, M; Filipe, J A

    2012-01-01

    This study intends to present a representation of a pensions fund through a stochastic network with two infinite servers nodes. With this representation it is allowed to deduce an equilibrium condition of the system with basis on the identity of the random rates expected values, for which the contributions arrive to the fund and the pensions are paid by the fund. In our study a stochastic network is constructed where traffic is represented. This network allows to study the equilibrium in the system and it is admissible to get a balance to a pensions fund. A specific case is studied. When the arrivals from outside at nodes A and B are according to a Poisson process, with rates λ A and λ B , respectively, the system may be seen as a two nodes network where the first node is a M/G/∞ queue and second a M t /G/∞ queue. For this case in the long term the conditions of equilibrium are as follows: m A λ A α A = m B (ρλ A + λ B )α B . In this formula it is established a relationship among the two nodes. Several examples are given in the study.

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

    Science.gov (United States)

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

    2016-01-01

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

  4. Worst-case efficient external-memory priority queues

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Katajainen, Jyrki

    1998-01-01

    A priority queue Q is a data structure that maintains a collection of elements, each element having an associated priority drawn from a totally ordered universe, under the operations Insert, which inserts an element into Q, and DeleteMin, which deletes an element with the minimum priority from Q....... In this paper a priority-queue implementation is given which is efficient with respect to the number of block transfers or I/Os performed between the internal and external memories of a computer. Let B and M denote the respective capacity of a block and the internal memory measured in elements. The developed...... data structure handles any intermixed sequence of Insert and DeleteMin operations such that in every disjoint interval of B consecutive priorityqueue operations at most clogM/B N/M I/Os are performed, for some positive constant c. These I/Os are divided evenly among the operations: if B ≥ clogM/B N...

  5. Measuring SIP proxy server performance

    CERN Document Server

    Subramanian, Sureshkumar V

    2013-01-01

    Internet Protocol (IP) telephony is an alternative to the traditional Public Switched Telephone Networks (PSTN), and the Session Initiation Protocol (SIP) is quickly becoming a popular signaling protocol for VoIP-based applications. SIP is a peer-to-peer multimedia signaling protocol standardized by the Internet Engineering Task Force (IETF), and it plays a vital role in providing IP telephony services through its use of the SIP Proxy Server (SPS), a software application that provides call routing services by parsing and forwarding all the incoming SIP packets in an IP telephony network.SIP Pr

  6. The weighted 2-server problem

    Czech Academy of Sciences Publication Activity Database

    Chrobak, M.; Sgall, Jiří

    2004-01-01

    Roč. 324, 2-3 (2004), s. 289-319 ISSN 0304-3975 R&D Projects: GA MŠk ME 103; GA MŠk ME 476; GA ČR GA201/01/1195; GA MŠk LN00A056; GA AV ČR IAA1019901; GA AV ČR IAA1019401 Institutional research plan: CEZ:AV0Z1019905 Keywords : online algorithms * k- server problem Subject RIV: BA - General Mathematics Impact factor: 0.676, year: 2004

  7. An Overview of Multimedia Proxy Servers

    Directory of Open Access Journals (Sweden)

    Philip Tse

    2004-08-01

    Full Text Available This paper gives an overview of the functions of the proxy servers in accessing multimedia objects over the Internet. The proxy servers use the cache replacement policies to select the cold objects to be removed from cache to release space. They use the object partitioning methods to divide each multimedia object into cacheable and non-cacheable parts. When the client bandwidth is insufficient to receive the original object, the proxy servers convert multimedia objects into objects of lower resolution in order to adapt to the client characteristics. When multiple proxy servers are present, they may work together in a cooperative manner to further enhance the cache efficiency or in a distributed manner to evenly spread the load. In summary, proxy servers become the centre of management with respect to the delivery of multimedia objects from web servers to clients over the Internet.

  8. Implementasi Proxy Server Dengan Linux Clear OS 5.2

    OpenAIRE

    Setiadi, Aprian

    2013-01-01

    Tugas Akhir ini membahas mengenai cara untuk membangun sebuah proxy server dalam jaringan LAN. Jaringan LAN yang dibangun menggunakan arsitektur topologi star dengan menjadikan komputer server sebagai Gateway Server dan Proxy Server, sehingga tidak membutuhkan perangkat tambahan Router yang berfungsi sebagai Gateway Server. Proxy Server yang yang dibangun menggunakan metode Transparent Mode, sehingga pada komputer klien tidak perlu mengkonfigurasi port proxy server pada Web Browser. Hasil ya...

  9. When Should a Roving Server Be Patient?

    OpenAIRE

    Mandyam M. Srinivasan; Diwakar Gupta

    1996-01-01

    When polling systems are used to model real-world systems, it is typically assumed that the server switches continuously ("roves") even when there are no waiting jobs in the system. However, requiring the server to be patient, instead of having it rove, might be more realistic. Furthermore, operational control of these systems can be improved by knowing answers to questions like "under what circumstances should be roving server be patient?" and "at which stations?". This paper analyzes the pa...

  10. Microsoft SQL Server 2012 with Hadoop

    CERN Document Server

    Sarkar, Debarchan

    2013-01-01

    This book will be a step-by-step tutorial, which practically teaches working with big data on SQL Server through sample examples in increasing complexity.Microsoft SQL Server 2012 with Hadoop is specifically targeted at readers who want to cross-pollinate their Hadoop skills with SQL Server 2012 business intelligence and data analytics. A basic understanding of traditional RDBMS technologies and query processing techniques is essential.

  11. Microsoft Windows Server 2012 administration instant reference

    CERN Document Server

    Hester, Matthew

    2013-01-01

    Fast, accurate answers for common Windows Server questions Serving as a perfect companion to all Windows Server books, this reference provides you with quick and easily searchable solutions to day-to-day challenges of Microsoft's newest version of Windows Server. Using helpful design features such as thumb tabs, tables of contents, and special heading treatments, this resource boasts a smooth and seamless approach to finding information. Plus, quick-reference tables and lists provide additional on-the-spot answers. Covers such key topics as server roles and functionality, u

  12. WSKE: Web Server Key Enabled Cookies

    Science.gov (United States)

    Masone, Chris; Baek, Kwang-Hyun; Smith, Sean

    In this paper, we present the design and prototype of a new approach to cookie management: if a server deposits a cookie only after authenticating itself via the SSL handshake, the browser will return the cookie only to a server that can authenticate itself, via SSL, to the same keypair. This approach can enable usable but secure client authentication. This approach can improve the usability of server authentication by clients. This approach is superior to the prior work on Active Cookies in that it defends against both DNS spoofing and IP spoofing—and does not require binding a user's interaction with a server to individual IP addresses.

  13. Mastering Microsoft Windows Small Business Server 2008

    CERN Document Server

    Johnson, Steven

    2010-01-01

    A complete, winning approach to the number one small business solution. Do you have 75 or fewer users or devices on your small-business network? Find out how to integrate everything you need for your mini-enterprise with Microsoft's new Windows Server 2008 Small Business Server, a custom collection of server and management technologies designed to help small operations run smoothly without a giant IT department. This comprehensive guide shows you how to master all SBS components as well as handle integration with other Microsoft technologies.: Focuses on Windows Server 2008 Small Business Serv

  14. Mastering Windows Server 2008 Networking Foundations

    CERN Document Server

    Minasi, Mark; Mueller, John Paul

    2011-01-01

    Find in-depth coverage of general networking concepts and basic instruction on Windows Server 2008 installation and management including active directory, DNS, Windows storage, and TCP/IP and IPv4 networking basics in Mastering Windows Server 2008 Networking Foundations. One of three new books by best-selling author Mark Minasi, this guide explains what servers do, how basic networking works (IP basics and DNS/WINS basics), and the fundamentals of the under-the-hood technologies that support staff must understand. Learn how to install Windows Server 2008 and build a simple network, security co

  15. Windows Server 2012 : Uudet ominaisuudet ja muutokset

    OpenAIRE

    Oksanen, Joni

    2013-01-01

    Tämän opintyön tarkoituksena on valottaa Windows Server 2012 -käyttöjärjestelmän muutoksia verrattuna vanhaan Windows Server 2008 R2 -versioon. Työ aloitettiin ennen Windows Server 2012 -julkaisua Release Candidate -version testauksella ja myöhemmin julkaisun jälkeen Windows Serverin kokeiluversiolla. Työssä on silti ajankohtaista tietoa Windows Server 2012:sta. Aluksi käsitellään Windows Servereiden kehityskaarta lyhyesti ja käsitellään uusinta Windows Serveriä tuotteena se...

  16. UniTree Name Server internals

    Energy Technology Data Exchange (ETDEWEB)

    Mecozzi, D.; Minton, J.

    1996-01-01

    The UniTree Name Server (UNS) is one of several servers which make up the UniTree storage system. The Name Server is responsible for mapping names to capabilities Names are generally human readable ASCII strings of any length. Capabilities are unique 256-bit identifiers that point to files, directories, or symbolic links. The Name Server implements a UNIX style hierarchical directory structure to facilitate name-to-capability mapping. The principal task of the Name Server is to manage the directories which make up the UniTree directory structure. The principle clients of the Name Server are the FTP Daemon, NFS and a few UniTree utility routines. However, the Name Server is a generalized server and will accept messages from any client. The purpose of this paper is to describe the internal workings of the UniTree Name Server. In cases where it seems appropriate, the motivation for a particular choice of algorithm as description of the algorithm itself will be given.

  17. CERN servers donated to Ghana

    CERN Document Server

    CERN Bulletin

    2012-01-01

    Cutting-edge research requires a constantly high performance of the computing equipment. At the CERN Computing Centre, computers typically need to be replaced after about four years of use. However, while servers may be withdrawn from cutting-edge use, they are still good for other uses elsewhere. This week, 220 servers and 30 routers were donated to the Kwame Nkrumah University of Science and Technology (KNUST) in Ghana.   “KNUST will provide a good home for these computers. The university has also developed a plan for using them to develop scientific collaboration with CERN,” said John Ellis, a professor at King’s College London and a visiting professor in CERN’s Theory Group.  John Ellis was heavily involved in building the relationship with Ghana, which started in 2006 when a Ghanaian participated in the CERN openlab student programme. Since 2007 CERN has hosted Ghanaians especially from KNUST in the framework of the CERN Summer Student Progr...

  18. The NASA Technical Report Server

    Science.gov (United States)

    Nelson, Michael L.; Gottlich, Gretchen L.; Bianco, David J.; Paulson, Sharon S.; Binkley, Robert L.; Kellogg, Yvonne D.; Beaumont, Chris J.; Schmunk, Robert B.; Kurtz, Michael J.; Accomazzi, Alberto

    1995-01-01

    The National Aeronautics and Space Act of 1958 established NASA and charged it to "provide for the widest practicable and appropriate dissemination of information concerning its activities and the results thereof." The search for innovative methods to distribute NASA's information lead a grass-roots team to create the NASA Technical Report Server (NTRS), which uses the World Wide Web and other popular Internet-based information systems as search engines. The NTRS is an inter-center effort which provides uniform access to various distributed publication servers residing on the Internet. Users have immediate desktop access to technical publications from NASA centers and institutes. The NTRS is comprised of several units, some constructed especially for inclusion in NTRS, and others that are existing NASA publication services that NTRS reuses. This paper presents the NTRS architecture, usage metrics, and the lessons learned while implementing and maintaining the service. The NTRS is largely constructed with freely available software running on existing hardware. NTRS builds upon existing hardware and software, and the resulting additional exposure for the body of literature contained ensures that NASA's institutional knowledge base will continue to receive the widest practicable and appropriate dissemination.

  19. HDF-EOS Web Server

    Science.gov (United States)

    Ullman, Richard; Bane, Bob; Yang, Jingli

    2008-01-01

    A shell script has been written as a means of automatically making HDF-EOS-formatted data sets available via the World Wide Web. ("HDF-EOS" and variants thereof are defined in the first of the two immediately preceding articles.) The shell script chains together some software tools developed by the Data Usability Group at Goddard Space Flight Center to perform the following actions: Extract metadata in Object Definition Language (ODL) from an HDF-EOS file, Convert the metadata from ODL to Extensible Markup Language (XML), Reformat the XML metadata into human-readable Hypertext Markup Language (HTML), Publish the HTML metadata and the original HDF-EOS file to a Web server and an Open-source Project for a Network Data Access Protocol (OPeN-DAP) server computer, and Reformat the XML metadata and submit the resulting file to the EOS Clearinghouse, which is a Web-based metadata clearinghouse that facilitates searching for, and exchange of, Earth-Science data.

  20. Studying the co-evolution of protein families with the Mirrortree web server.

    Science.gov (United States)

    Ochoa, David; Pazos, Florencio

    2010-05-15

    The Mirrortree server allows to graphically and interactively study the co-evolution of two protein families, and investigate their possible interactions and functional relationships in a taxonomic context. The server includes the possibility of starting from single sequences and hence it can be used by non-expert users. The web server is freely available at http://csbg.cnb.csic.es/mtserver. It was tested in the main web browsers. Adobe Flash Player is required at the client side to perform the interactive assessment of co-evolution. pazos@cnb.csic.es Supplementary data are available at Bioinformatics online.

  1. Integrating multiple data types into a useful whole with the Live Access Server

    Science.gov (United States)

    Callahan, J.; Hankin, S.

    2006-05-01

    The Live Access Server (LAS) is a highly configurable Web server designed to provide flexible access to geo- referenced scientific data. It can be used to unify access to multiple types of data in a single interface and to create thematic data servers from distributed data sources. Much of the focus of LAS has been on creating configurable solutions that can adapt to the changing needs of observational networks. This talk will discuss recent examples where LAS has been used as a data integrator for collections of observational data of various types as well as satellite products and model output.

  2. Autonomous Hybrid Priority Queueing for Scheduling Residential Energy Demands

    Science.gov (United States)

    Kalimullah, I. Q.; Shamroukh, M.; Sahar, N.; Shetty, S.

    2017-05-01

    The advent of smart grid technologies has opened up opportunities to manage the energy consumption of the users within a residential smart grid system. Demand response management is particularly being employed to reduce the overall load on an electricity network which could in turn reduce outages and electricity costs. The objective of this paper is to develop an intelligible scheduler to optimize the energy available to a micro grid through hybrid queueing algorithm centered around the consumers’ energy demands. This is achieved by shifting certain schedulable load appliances to light load hours. Various factors such as the type of demand, grid load, consumers’ energy usage patterns and preferences are considered while formulating the logical constraints required for the algorithm. The algorithm thus obtained is then implemented in MATLAB workspace to simulate its execution by an Energy Consumption Scheduler (ECS) found within smart meters, which automatically finds the optimal energy consumption schedule tailor made to fit each consumer within the micro grid network.

  3. Genonets server-a web server for the construction, analysis and visualization of genotype networks.

    Science.gov (United States)

    Khalid, Fahad; Aguilar-Rodríguez, José; Wagner, Andreas; Payne, Joshua L

    2016-07-08

    A genotype network is a graph in which vertices represent genotypes that have the same phenotype. Edges connect vertices if their corresponding genotypes differ in a single small mutation. Genotype networks are used to study the organization of genotype spaces. They have shed light on the relationship between robustness and evolvability in biological systems as different as RNA macromolecules and transcriptional regulatory circuits. Despite the importance of genotype networks, no tool exists for their automatic construction, analysis and visualization. Here we fill this gap by presenting the Genonets Server, a tool that provides the following features: (i) the construction of genotype networks for categorical and univariate phenotypes from DNA, RNA, amino acid or binary sequences; (ii) analyses of genotype network topology and how it relates to robustness and evolvability, as well as analyses of genotype network topography and how it relates to the navigability of a genotype network via mutation and natural selection; (iii) multiple interactive visualizations that facilitate exploratory research and education. The Genonets Server is freely available at http://ieu-genonets.uzh.ch. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  4. What's New in Apache Web Server 22?

    CERN Document Server

    Bowen, Rich

    2007-01-01

    What's New in Apache Web Server 2.2? shows you all the new features you'll know to set up and administer the Apache 2.2 web server. Learn how to take advantage of its improved caching, proxying, authentication, and other improvements in your Web 2.0 applications.

  5. Racing toward client-server solutions.

    Science.gov (United States)

    Cupito, M C

    1998-08-01

    If mainframe computing is like driving a reliable sedan, some experts say client-server computing is like driving a fast, maneuverable sports car. But until you understand and fine-tune a client-server system, performance can be disappointing.

  6. Performance of a distributed superscalar storage server

    Science.gov (United States)

    Finestead, Arlan; Yeager, Nancy

    1993-01-01

    The RS/6000 performed well in our test environment. The potential exists for the RS/6000 to act as a departmental server for a small number of users, rather than as a high speed archival server. Multiple UniTree Disk Server's utilizing one UniTree Disk Server's utilizing one UniTree Name Server could be developed that would allow for a cost effective archival system. Our performance tests were clearly limited by the network bandwidth. The performance gathered by the LibUnix testing shows that UniTree is capable of exceeding ethernet speeds on an RS/6000 Model 550. The performance of FTP might be significantly faster if asked to perform across a higher bandwidth network. The UniTree Name Server also showed signs of being a potential bottleneck. UniTree sites that would require a high ratio of file creations and deletions to reads and writes would run into this bottleneck. It is possible to improve the UniTree Name Server performance by bypassing the UniTree LibUnix Library altogether and communicating directly with the UniTree Name Server and optimizing creations. Although testing was performed in a less than ideal environment, hopefully the performance statistics stated in this paper will give end-users a realistic idea as to what performance they can expect in this type of setup.

  7. You're a What? Process Server

    Science.gov (United States)

    Torpey, Elka

    2012-01-01

    In this article, the author talks about the role and functions of a process server. The job of a process server is to hand deliver legal documents to the people involved in court cases. These legal documents range from a summons to appear in court to a subpoena for producing evidence. Process serving can involve risk, as some people take out their…

  8. Building mail server on distributed computing system

    International Nuclear Information System (INIS)

    Akihiro Shibata; Osamu Hamada; Tomoko Oshikubo; Takashi Sasaki

    2001-01-01

    The electronic mail has become the indispensable function in daily job, and the server stability and performance are required. Using DCE and DFS we have built the distributed electronic mail sever, that is, servers such as SMTP, IMAP are distributed symmetrically, and provides the seamless access

  9. Analisis Perbandingan Respons Time Squid Proxy Pada Windows Server dan Linux Server

    OpenAIRE

    Sirait, Parulian

    2016-01-01

    In the development of information technology, information is obtained quickly through technology computer network known as the Internet. The use bandwidth for Internet access can be maximized by using a proxy server. One of the proxy server is squid. The use squid as the proxy server need to consider the operating system on the server and have not known its best performance on any operating system yet. For that it is necessary to analyze the performance of squid proxy server on a different op...

  10. CentroidFold: a web server for RNA secondary structure prediction

    OpenAIRE

    Sato, Kengo; Hamada, Michiaki; Asai, Kiyoshi; Mituyama, Toutai

    2009-01-01

    The CentroidFold web server (http://www.ncrna.org/centroidfold/) is a web application for RNA secondary structure prediction powered by one of the most accurate prediction engine. The server accepts two kinds of sequence data: a single RNA sequence and a multiple alignment of RNA sequences. It responses with a prediction result shown as a popular base-pair notation and a graph representation. PDF version of the graph representation is also available. For a multiple alignment sequence, the ser...

  11. NCI's Distributed Geospatial Data Server

    Science.gov (United States)

    Larraondo, P. R.; Evans, B. J. K.; Antony, J.

    2016-12-01

    Earth systems, environmental and geophysics datasets are an extremely valuable source of information about the state and evolution of the Earth. However, different disciplines and applications require this data to be post-processed in different ways before it can be used. For researchers experimenting with algorithms across large datasets or combining multiple data sets, the traditional approach to batch data processing and storing all the output for later analysis rapidly becomes unfeasible, and often requires additional work to publish for others to use. Recent developments on distributed computing using interactive access to significant cloud infrastructure opens the door for new ways of processing data on demand, hence alleviating the need for storage space for each individual copy of each product. The Australian National Computational Infrastructure (NCI) has developed a highly distributed geospatial data server which supports interactive processing of large geospatial data products, including satellite Earth Observation data and global model data, using flexible user-defined functions. This system dynamically and efficiently distributes the required computations among cloud nodes and thus provides a scalable analysis capability. In many cases this completely alleviates the need to preprocess and store the data as products. This system presents a standards-compliant interface, allowing ready accessibility for users of the data. Typical data wrangling problems such as handling different file formats and data types, or harmonising the coordinate projections or temporal and spatial resolutions, can now be handled automatically by this service. The geospatial data server exposes functionality for specifying how the data should be aggregated and transformed. The resulting products can be served using several standards such as the Open Geospatial Consortium's (OGC) Web Map Service (WMS) or Web Feature Service (WFS), Open Street Map tiles, or raw binary arrays under

  12. Client-server Sistem Informasi Ulam Bebantenan

    Directory of Open Access Journals (Sweden)

    A.A. Gede Brampramana Putra

    2016-01-01

    Full Text Available Sistem Informasi ulam bebantenan adalah sistem informasi yangmelangsungkan hubungan antaraclientdanserverdalam proses perpindahana data informasi. Ulam bebantenan adalah sarana pelengkap yang digunakan pada beberapa jenis banten. Informasi yang disajikan dalam sistem adalah berupa deksripsi ulam hingga pada proses pengolahannya. Aplikasi client dibangun pada perangkat mobile dengan sistem operasi Android.Aplikasi client memberikan informasi terkait teks deskripsi, gambar, serta video mengenai Ulam Bebantenan di Bali.Sisi server dibangun dengan berbasiskan web.Server memiliki peran dalam mengelola data master pada basis data sistem. Hubungan yang terjadi pada client-server ini berperan dalam agar pada sisi client dapat mengakses data pada basis data sistem yang terdapat pada sisi server secara berkala.   Kata kunci: Client-server, Informasi, Ulam Bebantenan, Android.

  13. MISTIC: mutual information server to infer coevolution

    DEFF Research Database (Denmark)

    Simonetti, Franco L.; Teppa, Elin; Chernomoretz, Ariel

    2013-01-01

    MISTIC (mutual information server to infer coevolution) is a web server for graphical representation of the information contained within a MSA (multiple sequence alignment) and a complete analysis tool for Mutual Information networks in protein families. The server outputs a graphical visualization...... containing all results can be downloaded. The server is available at http://mistic.leloir.org.ar. In summary, MISTIC allows for a comprehensive, compact, visually rich view of the information contained within an MSA in a manner unique to any other publicly available web server. In particular, the use...... of several information-related quantities using a circos representation. This provides an integrated view of the MSA in terms of (i) the mutual information (MI) between residue pairs, (ii) sequence conservation and (iii) the residue cumulative and proximity MI scores. Further, an interactive interface...

  14. A Scalability Model for ECS's Data Server

    Science.gov (United States)

    Menasce, Daniel A.; Singhal, Mukesh

    1998-01-01

    This report presents in four chapters a model for the scalability analysis of the Data Server subsystem of the Earth Observing System Data and Information System (EOSDIS) Core System (ECS). The model analyzes if the planned architecture of the Data Server will support an increase in the workload with the possible upgrade and/or addition of processors, storage subsystems, and networks. The approaches in the report include a summary of the architecture of ECS's Data server as well as a high level description of the Ingest and Retrieval operations as they relate to ECS's Data Server. This description forms the basis for the development of the scalability model of the data server and the methodology used to solve it.

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

    Directory of Open Access Journals (Sweden)

    Charles Knessl

    1996-01-01

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

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

    Science.gov (United States)

    2015-06-01

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

  17. Real-time prediction of queues at signalized intersections to support eco-driving applications.

    Science.gov (United States)

    2014-10-01

    The overall objective of this research is to develop models for predicting queue lengths at signalized intersections based on : the data from probe vehicles. The time and space coordinates of the probe vehicles going through signalized intersections ...

  18. IntFOLD: an integrated server for modelling protein structures and functions from amino acid sequences.

    Science.gov (United States)

    McGuffin, Liam J; Atkins, Jennifer D; Salehe, Bajuna R; Shuid, Ahmad N; Roche, Daniel B

    2015-07-01

    IntFOLD is an independent web server that integrates our leading methods for structure and function prediction. The server provides a simple unified interface that aims to make complex protein modelling data more accessible to life scientists. The server web interface is designed to be intuitive and integrates a complex set of quantitative data, so that 3D modelling results can be viewed on a single page and interpreted by non-expert modellers at a glance. The only required input to the server is an amino acid sequence for the target protein. Here we describe major performance and user interface updates to the server, which comprises an integrated pipeline of methods for: tertiary structure prediction, global and local 3D model quality assessment, disorder prediction, structural domain prediction, function prediction and modelling of protein-ligand interactions. The server has been independently validated during numerous CASP (Critical Assessment of Techniques for Protein Structure Prediction) experiments, as well as being continuously evaluated by the CAMEO (Continuous Automated Model Evaluation) project. The IntFOLD server is available at: http://www.reading.ac.uk/bioinf/IntFOLD/. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  19. SciServer Compute brings Analysis to Big Data in the Cloud

    Science.gov (United States)

    Raddick, Jordan; Medvedev, Dmitry; Lemson, Gerard; Souter, Barbara

    2016-06-01

    SciServer Compute uses Jupyter Notebooks running within server-side Docker containers attached to big data collections to bring advanced analysis to big data "in the cloud." SciServer Compute is a component in the SciServer Big-Data ecosystem under development at JHU, which will provide a stable, reproducible, sharable virtual research environment.SciServer builds on the popular CasJobs and SkyServer systems that made the Sloan Digital Sky Survey (SDSS) archive one of the most-used astronomical instruments. SciServer extends those systems with server-side computational capabilities and very large scratch storage space, and further extends their functions to a range of other scientific disciplines.Although big datasets like SDSS have revolutionized astronomy research, for further analysis, users are still restricted to downloading the selected data sets locally - but increasing data sizes make this local approach impractical. Instead, researchers need online tools that are co-located with data in a virtual research environment, enabling them to bring their analysis to the data.SciServer supports this using the popular Jupyter notebooks, which allow users to write their own Python and R scripts and execute them on the server with the data (extensions to Matlab and other languages are planned). We have written special-purpose libraries that enable querying the databases and other persistent datasets. Intermediate results can be stored in large scratch space (hundreds of TBs) and analyzed directly from within Python or R with state-of-the-art visualization and machine learning libraries. Users can store science-ready results in their permanent allocation on SciDrive, a Dropbox-like system for sharing and publishing files. Communication between the various components of the SciServer system is managed through SciServer‘s new Single Sign-on Portal.We have created a number of demos to illustrate the capabilities of SciServer Compute, including Python and R scripts

  20. KEAMANAN JARINGAN MENGGUNAKAN UNIFIED THREAT MANAGEMENT PADA SERVER BERBASISKAN LINUX

    Directory of Open Access Journals (Sweden)

    Bambang Heru

    2007-05-01

    Full Text Available UTM is an application which integrated many security features become a single hardware platform. The reasonbehind this research is to build a system that protects the network in St. Bellarminus school. Research method that hasbeen used in this research is spiral method, whereas the development of the application is continues and can be modifiedeasily if there is new version of the security tools implemented in the application, or if there is a better security tools to beused. The outcome of the system is very good, because it can protects the network: cross-platform firewall, IntrusionDetection System, Proxy Server, email protection against virus and spam. In conclusion, the application can producehigh effectiveness with low cost and this application is very useful in monitoring and configuring the network in St.Bellarminus school.Keywords: security network, unified threat management, anti virus, server, proxy, firewall

  1. The SDSS data archive server

    Energy Technology Data Exchange (ETDEWEB)

    Neilsen, Eric H., Jr.; /Fermilab

    2007-10-01

    The Sloan Digital Sky Survey (SDSS) Data Archive Server (DAS) provides public access to data files produced by the SDSS data reduction pipeline. This article discusses challenges in public distribution of data of this volume and complexity, and how the project addressed them. The Sloan Digital Sky Survey (SDSS)1 is an astronomical survey of covering roughly one quarter of the night sky. It contains images of this area, a catalog of almost 300 million objects detected in those images, and spectra of more than a million of these objects. The catalog of objects includes a variety of data on each object. These data include not only basic information but also fit parameters for a variety of models, classifications by sophisticated object classification algorithms, statistical parameters, and more. If the survey contains the spectrum of an object, the catalog includes a variety of other parameters derived from its spectrum. Data processing and catalog generation, described more completely in the SDSS Early Data Release2 paper, consists of several stages: collection of imaging data, processing of imaging data, selection of spectroscopic targets from catalogs generated from the imaging data, collection of spectroscopic data, processing of spectroscopic data, and loading of processed data into a database. Each of these stages is itself a complex process. For example, the software that processes the imaging data determines and removes some instrumental signatures in the raw images to create 'corrected frames', models the point spread function, models and removes the sky background, detects objects, measures object positions, measures the radial profile and other morphological parameters for each object, measures the brightness of each object using a variety of methods, classifies the objects, calibrates the brightness measurements against survey standards, and produces a variety of quality assurance plots and diagnostic tables. The complexity of the spectroscopic

  2. Server for experimental data from LHD

    International Nuclear Information System (INIS)

    Emoto, M.; Ohdachi, S.; Watanabe, K.; Sudo, S.; Nagayama, Y.

    2006-01-01

    In order to unify various types of data, the Kaiseki Server was developed. This server provides physical experimental data of large helical device (LHD) experiments. Many types of data acquisition systems currently exist in operation, and they produce files of various formats. Therefore, it has been difficult to analyze different types of acquisition data at the same time because the data of each system should be read in a particular manner. To facilitate the usage of this data by researchers, the authors have developed a new server system, which provides a unified data format and a unique data retrieval interface. Although the Kaiseki Server satisfied the initial demand, new requests arose from researchers, one of which was the remote usage of the server. The current system cannot be used remotely because of security issues. Another request was group ownership, i.e., users belonging to the same group should have equal access to data. To satisfy these demands, the authors modified the server. However, since other requests may arise in the future, the new system must be flexible so that it can satisfy future demands. Therefore, the authors decided to develop a new server using a three-tier structure

  3. Server for experimental data from LHD

    Energy Technology Data Exchange (ETDEWEB)

    Emoto, M. [National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292 (Japan)]. E-mail: emo@nifs.ac.jp; Ohdachi, S. [National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292 (Japan); Watanabe, K. [National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292 (Japan); Sudo, S. [National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292 (Japan); Nagayama, Y. [National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292 (Japan)

    2006-07-15

    In order to unify various types of data, the Kaiseki Server was developed. This server provides physical experimental data of large helical device (LHD) experiments. Many types of data acquisition systems currently exist in operation, and they produce files of various formats. Therefore, it has been difficult to analyze different types of acquisition data at the same time because the data of each system should be read in a particular manner. To facilitate the usage of this data by researchers, the authors have developed a new server system, which provides a unified data format and a unique data retrieval interface. Although the Kaiseki Server satisfied the initial demand, new requests arose from researchers, one of which was the remote usage of the server. The current system cannot be used remotely because of security issues. Another request was group ownership, i.e., users belonging to the same group should have equal access to data. To satisfy these demands, the authors modified the server. However, since other requests may arise in the future, the new system must be flexible so that it can satisfy future demands. Therefore, the authors decided to develop a new server using a three-tier structure.

  4. Sistem Pengukur Suhu dan Kelembaban Ruang Server

    Directory of Open Access Journals (Sweden)

    Muhammad Fahmi Awaj

    2014-01-01

    Full Text Available Makalah ini membahas tentang perancangan sistem pengukur suhu dan kelembaban ruang server yang dapat meningkatkan efisiensi daya listrik dengan menggunakan arduino. Sistem terdiri dari sensor DHT 11 yang berfungsi untuk mengambil data berupa suhu dan kelembaban ruang server kemudian ditampilkan dalam LCD 16x2. Data suhu dan kelembaban ditampilkan juga ke dalam website dengan menggunakan IP address tertentu yang sebelumnya board arduino telah terhubung dengan ethernet shield. Suhu yang melebihi 270C akan menyalakan relay dan kipas serta sistem akan mengirim peringatan sms secara otomatis kepada administrator ruang server melalui sistem sms secara periodik hanya setiap tiga detik. Sistem peringatan sms akan berhenti jika suhu kurang 270C.

  5. Getting started with SQL Server 2014 administration

    CERN Document Server

    Ellis, Gethyn

    2014-01-01

    This is an easytofollow handson tutorial that includes real world examples of SQL Server 2014's new features. Each chapter is explained in a stepbystep manner which guides you to implement the new technology.If you want to create an highly efficient database server then this book is for you. This book is for database professionals and system administrators who want to use the added features of SQL Server 2014 to create a hybrid environment, which is both highly available and allows you to get the best performance from your databases.

  6. Optimizing queries in SQL Server 2008

    Directory of Open Access Journals (Sweden)

    Ion LUNGU

    2010-05-01

    Full Text Available Starting from the need to develop efficient IT systems, we intend to review theoptimization methods and tools that can be used by SQL Server database administratorsand developers of applications based on Microsoft technology, focusing on the latestversion of the proprietary DBMS, SQL Server 2008. We’ll reflect on the objectives tobe considered in improving the performance of SQL Server instances, we will tackle themostly used techniques for analyzing and optimizing queries and we will describe the“Optimize for ad hoc workloads”, “Plan Freezing” and “Optimize for unknown" newoptions, accompanied by relevant code examples.

  7. Windows Server 2012 ja Active Directory

    OpenAIRE

    Eteläaho, Antti

    2015-01-01

    Opinnäytetyön aiheena oli tutustua Windows Server 2012–ohjelmiston sisältämiin palveluihin sekä perehtyä tarkemmin Active Directoryn peruskäyttöön. Tavoitteena oli antaa lukijalle ymmärrys Windows Server 2012–ohjelmiston tarjoamista käyttömahdollisuuksista ja Active Directoryn käytöstä. Opinnäytetyön tietoperusta koostui virtuaaliympäristön käytöstä ja erilaisista Windows Server 2012–ohjelman palveluista. Tietoperusta kattoi esimerkiksi seuraavat käsitteet: Virtuaalisointi, Emulointi, Ohj...

  8. Personalized Pseudonyms for Servers in the Cloud

    OpenAIRE

    Xiao Qiuyu; Reiter Michael K.; Zhang Yinqian

    2017-01-01

    A considerable and growing fraction of servers, especially of web servers, is hosted in compute clouds. In this paper we opportunistically leverage this trend to improve privacy of clients from network attackers residing between the clients and the cloud: We design a system that can be deployed by the cloud operator to prevent a network adversary from determining which of the cloud’s tenant servers a client is accessing. The core innovation in our design is a PoPSiCl (pronounced “popsicle”), ...

  9. Web server with ATMEGA 2560 microcontroller

    Science.gov (United States)

    Răduca, E.; Ungureanu-Anghel, D.; Nistor, L.; Haţiegan, C.; Drăghici, S.; Chioncel, C.; Spunei, E.; Lolea, R.

    2016-02-01

    This paper presents the design and building of a Web Server to command, control and monitor at a distance lots of industrial or personal equipments and/or sensors. The server works based on a personal software. The software can be written by users and can work with many types of operating system. The authors were realized the Web server based on two platforms, an UC board and a network board. The source code was written in "open source" language Arduino 1.0.5.

  10. WEB-server for search of a periodicity in amino acid and nucleotide sequences

    Science.gov (United States)

    E Frenkel, F.; Skryabin, K. G.; Korotkov, E. V.

    2017-12-01

    A new web server (http://victoria.biengi.ac.ru/splinter/login.php) was designed and developed to search for periodicity in nucleotide and amino acid sequences. The web server operation is based upon a new mathematical method of searching for multiple alignments, which is founded on the position weight matrices optimization, as well as on implementation of the two-dimensional dynamic programming. This approach allows the construction of multiple alignments of the indistinctly similar amino acid and nucleotide sequences that accumulated more than 1.5 substitutions per a single amino acid or a nucleotide without performing the sequences paired comparisons. The article examines the principles of the web server operation and two examples of studying amino acid and nucleotide sequences, as well as information that could be obtained using the web server.

  11. RCD+: Fast loop modeling server.

    Science.gov (United States)

    López-Blanco, José Ramón; Canosa-Valls, Alejandro Jesús; Li, Yaohang; Chacón, Pablo

    2016-07-08

    Modeling loops is a critical and challenging step in protein modeling and prediction. We have developed a quick online service (http://rcd.chaconlab.org) for ab initio loop modeling combining a coarse-grained conformational search with a full-atom refinement. Our original Random Coordinate Descent (RCD) loop closure algorithm has been greatly improved to enrich the sampling distribution towards near-native conformations. These improvements include a new workflow optimization, MPI-parallelization and fast backbone angle sampling based on neighbor-dependent Ramachandran probability distributions. The server starts by efficiently searching the vast conformational space from only the loop sequence information and the environment atomic coordinates. The generated closed loop models are subsequently ranked using a fast distance-orientation dependent energy filter. Top ranked loops are refined with the Rosetta energy function to obtain accurate all-atom predictions that can be interactively inspected in an user-friendly web interface. Using standard benchmarks, the average root mean squared deviation (RMSD) is 0.8 and 1.4 Å for 8 and 12 residues loops, respectively, in the challenging modeling scenario in where the side chains of the loop environment are fully remodeled. These results are not only very competitive compared to those obtained with public state of the art methods, but also they are obtained ∼10-fold faster. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

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

    Directory of Open Access Journals (Sweden)

    Xinhua He

    2017-01-01

    Full Text Available Extreme rainstorm is a main factor to cause urban floods when urban drainage system cannot discharge stormwater successfully. This paper investigates distribution feature of rainstorms and draining process of urban drainage systems and uses a two-stage single-counter queue method M/M/1→M/D/1 to model urban drainage system. The model emphasizes randomness of extreme rainstorms, fuzziness of draining process, and construction and operation cost of drainage system. Its two objectives are total cost of construction and operation and overall sojourn time of stormwater. An improved genetic algorithm is redesigned to solve this complex nondeterministic problem, which incorporates with stochastic and fuzzy characteristics in whole drainage process. A numerical example in Shanghai illustrates how to implement the model, and comparisons with alternative algorithms show its performance in computational flexibility and efficiency. Discussions on sensitivity of four main parameters, that is, quantity of pump stations, drainage pipe diameter, rainstorm precipitation intensity, and confidence levels, are also presented to provide guidance for designing urban drainage system.

  13. Care on demand in nursing homes: a queueing theoretic approach.

    Science.gov (United States)

    van Eeden, Karin; Moeke, Dennis; Bekker, René

    2016-09-01

    Nursing homes face ever-tightening healthcare budgets and are searching for ways to increase the efficiency of their healthcare processes without losing sight of the needs of their residents. Optimizing the allocation of care workers plays a key role in this search as care workers are responsible for the daily care of the residents and account for a significant proportion of the total labor expenses. In practice, the lack of reliable data makes it difficult for nursing home managers to make informed staffing decisions. The focus of this study lies on the 'care on demand' process in a Belgian nursing home. Based on the analysis of real-life 'call button' data, a queueing model is presented which can be used by nursing home managers to determine the number of care workers required to meet a specific service level. Based on numerical experiments an 80/10 service level is proposed for this nursing home, meaning that at least 80 percent of the clients should receive care within 10 minutes after a call button request. To the best of our knowledge, this is the first attempt to develop a quantitative model for the 'care on demand' process in a nursing home.

  14. Mastering Windows Server 2012 R2

    CERN Document Server

    Minasi, Mark; Booth, Christian; Butler, Robert; McCabe, John; Panek, Robert; Rice, Michael; Roth, Stefan

    2013-01-01

    Check out the new Hyper-V, find new and easier ways to remotely connect back into the office, or learn all about Storage Spaces-these are just a few of the features in Windows Server 2012 R2 that are explained in this updated edition from Windows authority Mark Minasi and a team of Windows Server experts led by Kevin Greene. This book gets you up to speed on all of the new features and functions of Windows Server, and includes real-world scenarios to put them in perspective. If you're a system administrator upgrading to, migrating to, or managing Windows Server 2012 R2, find what you need to

  15. Miniaturized Airborne Imaging Central Server System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is a miniaturized airborne imaging central server system (MAICSS). MAICSS is designed as a high-performance-computer-based electronic backend that...

  16. Miniaturized Airborne Imaging Central Server System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is a miniaturized airborne imaging central server system (MAICSS). MAICSS is designed as a high-performance computer-based electronic backend that...

  17. PlanetServer/EarthServer: Big Data analytics in Planetary Science

    Science.gov (United States)

    Pio Rossi, Angelo; Oosthoek, Jelmer; Baumann, Peter; Beccati, Alan; Cantini, Federico; Misev, Dimitar; Orosei, Roberto; Flahaut, Jessica; Campalani, Piero; Unnithan, Vikram

    2014-05-01

    Planetary data are freely available on PDS/PSA archives and alike (e.g. Heather et al., 2013). Their exploitation by the community is somewhat limited by the variable availability of calibrated/higher level datasets. An additional complexity of these multi-experiment, multi-mission datasets is related to the heterogeneity of data themselves, rather than their volume. Orbital - so far - data are best suited for an inclusion in array databases (Baumann et al., 1994). Most lander- or rover-based remote sensing experiment (and possibly, in-situ as well) are suitable for similar approaches, although the complexity of coordinate reference systems (CRS) is higher in the latter case. PlanetServer, the Planetary Service of the EC FP7 e-infrastructure project EarthServer (http://earthserver.eu) is a state-of-art online data exploration and analysis system based on the Open Geospatial Consortium (OGC) standards for Mars orbital data. It provides access to topographic, panchromatic, multispectral and hyperspectral calibrated data. While its core focus has been on hyperspectral data analysis through the OGC Web Coverage Processing Service (Oosthoek et al., 2013; Rossi et al., 2013), the Service progressively expanded to host also sounding radar data (Cantini et al., this volume). Additionally, both single swath and mosaicked imagery and topographic data are being added to the Service, deriving from the HRSC experiment (e.g. Jaumann et al., 2007; Gwinner et al., 2009) The current Mars-centric focus can be extended to other planetary bodies and most components are general purpose ones, making possible its application to the Moon, Mercury or alike. The Planetary Service of EarthServer is accessible on http://www.planetserver.eu References: Baumann, P. (1994) VLDB J. 4 (3), 401-444, Special Issue on Spatial Database Systems. Cantini, F. et al. (2014) Geophys. Res. Abs., Vol. 16, #EGU2014-3784, this volume Heather, D., et al.(2013) EuroPlanet Sci. Congr. #EPSC2013-626 Gwinner, K

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

    Directory of Open Access Journals (Sweden)

    Abdullah ÖZÇİL

    2015-06-01

    Full Text Available Despite the appreciable increase in the number of bank branches every year, nowadays queues for services don’t decrease and even become parts of our daily lives. By minimizing waiting processes the least, increasing customer satisfaction should be one of branch managers’ main goals. A quick and also customer oriented service with high quality is the most important factor for customer loyalty. In this study, Queueing theory, one of Operation Research techniques, is handled and in application, the data are obtained related to waiting in queue of customer in six different branches of two banks operating in Denizli and then they are analyzed by Queueing theory and also calculated the average effectiveness of the system. The study’s data are obtained by six branches of two banks called as A1, A2, A3, B1, B2 and B3. At the end of study it is presented to the company some advices that can bring benefits to the staff and customers. In this study, Queueing theory, one of Operation Research techniques, is handled and in application, the data are obtained related to waiting in queue of customer in three different branches of a bank operating in Denizli and then they are analyzed by Queueing theory and also calculated the average effectiveness of the system. The study’s data are obtained by three branches of the bank called A1, A2 and A3. At last it is presented to the company some advices that can bring more benefits to the staff and clients.

  19. Conversation Threads Hidden within Email Server Logs

    Science.gov (United States)

    Palus, Sebastian; Kazienko, Przemysław

    Email server logs contain records of all email Exchange through this server. Often we would like to analyze those emails not separately but in conversation thread, especially when we need to analyze social network extracted from those email logs. Unfortunately each mail is in different record and those record are not tided to each other in any obvious way. In this paper method for discussion threads extraction was proposed together with experiments on two different data sets - Enron and WrUT..

  20. ENHANCING THE IMPREGNABILITY OF LINUX SERVERS

    OpenAIRE

    Rama Koteswara Rao G; Satya Prasad R; Pathanjali Sastri A; P. E. S. N. Prasad

    2014-01-01

    Worldwide IT industry is experiencing a rapid shift towards Service Oriented Architecture (SOA). As a response to the current trend, all the IT firms are adopting business models such as cloud based services which rely on reliable and highly available server platforms. Linux servers are known to be highly secure. Network security thus becomes a major concern to all IT organizations offering cloud based services. The fundamental form of attack on network security is Denial of S...

  1. Measurement and Evaluation of ENUM Server Performance

    OpenAIRE

    Shen, Charles; Schulzrinne, Henning

    2008-01-01

    ENUM is a DNS-based protocol standard for mapping E.164 telephone numbers to Internet Uniform Resource Identifiers (URIs). It places unique requirements on the existing DNS infrastructure, such as data scalability, query throughput, response time, and database update rates. This paper measures and evaluates the performance of existing name server implementation as ENUM servers. We compared PowerDNS (PDNS), BIND and Navitas. Results show that BIND is not suitable for ENUM due to its poor scali...

  2. Microsoft SQL Server OLAP Solution - A Survey

    OpenAIRE

    Badiozamany, Sobhan

    2010-01-01

    Microsoft SQL Server 2008 offers technologies for performing On-Line Analytical Processing (OLAP), directly on data stored in data warehouses, instead of moving the data into some offline OLAP tool. This brings certain benefits, such as elimination of data copying and better integration with the DBMS compared with off-line OLAP tools. This report reviews SQL Server support for OLAP, solution architectures, tools and components involved. Standard storage options are discussed but the focus of ...

  3. APLIKASI SERVER VIRTUAL IP UNTUK MIKROKONTROLER

    OpenAIRE

    Ashari, Ahmad

    2008-01-01

    Selama ini mikrokontroler yang terhubung ke satu komputer hanya dapat diakses melalui satu IP saja, padahal kebanyakan sistem operasi sekarang dapat memperjanjikan lebih dari satu IP untuk setiap komputer dalam bentuk virtual IP. Penelitian ini mengkaji pemanfaatan virtual IP dari IP aliasing pada sistem operasi Linux sebagai Server Virtual IP untuk mikrokontroler. Prinsip dasar Server Virtual IP adalah pembuatan Virtual Host pada masing-masing IP untuk memproses paket-paket data dan menerjem...

  4. An Erlang Loss Queue with Time-Phased Batch Arrivals as a Model for Traffic Control in Communication Networks

    Directory of Open Access Journals (Sweden)

    Moon Ho Lee

    2008-01-01

    Full Text Available A multiserver queueing model that does not have a buffer but has batch arrival of customers is considered. In contrast to the standard batch arrival, in which the entire batch arrives at the system during a single epoch, we assume that the customers of a batch (flow arrive individually in exponentially distributed times. The service time is exponentially distributed. Flows arrive according to a stationary Poisson arrival process. The flow size distribution is geometric. The number of flows that can be simultaneously admitted to the system is under control. The loss of any customer from an admitted flow, with a fixed probability, implies termination of the flow arrival. Analysis of the sojourn time and loss probability of an arbitrary flow is performed.

  5. Beginning SQL Server Modeling Model-driven Application Development in SQL Server

    CERN Document Server

    Weller, Bart

    2010-01-01

    Get ready for model-driven application development with SQL Server Modeling! This book covers Microsoft's SQL Server Modeling (formerly known under the code name "Oslo") in detail and contains the information you need to be successful with designing and implementing workflow modeling. Beginning SQL Server Modeling will help you gain a comprehensive understanding of how to apply DSLs and other modeling components in the development of SQL Server implementations. Most importantly, after reading the book and working through the examples, you will have considerable experience using SQL M

  6. FFAS server: novel features and applications.

    Science.gov (United States)

    Jaroszewski, Lukasz; Li, Zhanwen; Cai, Xiao-hui; Weber, Christoph; Godzik, Adam

    2011-07-01

    The Fold and Function Assignment System (FFAS) server [Jaroszewski et al. (2005) FFAS03: a server for profile-profile sequence alignments. Nucleic Acids Research, 33, W284-W288] implements the algorithm for protein profile-profile alignment introduced originally in [Rychlewski et al. (2000) Comparison of sequence profiles. Strategies for structural predictions using sequence information. Protein Science: a Publication of the Protein Society, 9, 232-241]. Here, we present updates, changes and novel functionality added to the server since 2005 and discuss its new applications. The sequence database used to calculate sequence profiles was enriched by adding sets of publicly available metagenomic sequences. The profile of a user's protein can now be compared with ∼20 additional profile databases, including several complete proteomes, human proteins involved in genetic diseases and a database of microbial virulence factors. A newly developed interface uses a system of tabs, allowing the user to navigate multiple results pages, and also includes novel functionality, such as a dotplot graph viewer, modeling tools, an improved 3D alignment viewer and links to the database of structural similarities. The FFAS server was also optimized for speed: running times were reduced by an order of magnitude. The FFAS server, http://ffas.godziklab.org, has no log-in requirement, albeit there is an option to register and store results in individual, password-protected directories. Source code and Linux executables for the FFAS program are available for download from the FFAS server.

  7. Analisis Kinerja Penerapan Container untuk Load Balancing Web Server

    Directory of Open Access Journals (Sweden)

    Muhammad Agung Nugroho

    2016-12-01

    Full Text Available Container merupakan teknologi virtualisasi terbaru. Container memudahkan system administrator dalam mengelola aplikasi pada server. Docker container dapat digunakan untuk membangun, mempersiapkan, dan menjalankan aplikasi. Dapat membuat aplikasi dari bahasa pemrograman yang berbeda pada lapisan apapun. Aplikasi dapat di bungkus dalam container, dan aplikasi dapat berjalan pada lingkungan apapun dimana saja.  Dalam perkembangannya container ini dapat digunakan untuk load balancing, dengan memanfaatkan HA Proxy. Load Balancing dapat digunakan untuk menyelesaikan permasalahan beban kinerja web server yang terlalu berat (overload terhadap permintaan. Load Balancing merupakan salah satu metode untuk meningkatkan skalabilitas web server sekaligus mengurangi beban kerja web server. Ujicoba dilakukan dengan memberikan beban request pada single container dan multi container, dan membandingkan kinerjanya. Analisis kinerja dapat dilakukan dengan menggunakan parameter performance pada processor, memori dan proses layanan. Penerapan ujicoba dilakukan pada raspberry pi. Hasil yang diperoleh multi container dapat digunakan untuk mengembangkan metode load balancing, hasil ujicoba menunjukkan performance raspberry pi dapat optimum karena pembagian beban processor.

  8. Exam 70-411 administering Windows Server 2012

    CERN Document Server

    Course, Microsoft Official Academic

    2014-01-01

    Microsoft Windows Server is a multi-purpose server designed to increase reliability and flexibility of  a network infrastructure. Windows Server is the paramount tool used by enterprises in their datacenter and desktop strategy. The most recent versions of Windows Server also provide both server and client virtualization. Its ubiquity in the enterprise results in the need for networking professionals who know how to plan, design, implement, operate, and troubleshoot networks relying on Windows Server. Microsoft Learning is preparing the next round of its Windows Server Certification program

  9. Novel cluster proxy server system for Internet applications

    Science.gov (United States)

    Chao, HanChieh; Chen, Weiming; Ong, Jong Jeen; Tsuei, T. K.

    1999-08-01

    The population using Internet is increased rapidly in the recent years. Thus the network bandwidth is not enough accordingly causing the information transmitted by slowly. Therefore, the function of proxy server is more and more important. The cluster proxy server system is composed of many independent proxy servers which can enlarge the disk cache by combing each independent proxy server and balance them. Cluster proxy servers can provide a higher cache `hit rate' than any independent proxy server. In the traditional cluster proxy server schemes such as Internet cache protocol or Hashing Routing Protocols, clients can not select proxy server location dynamically and it will increase the time of searching the related documents. In this paper, a new cluster proxy server structure is proposed and called the dispatching cluster proxy server system.

  10. Method and apparatus for efficiently tracking queue entries relative to a timestamp

    Science.gov (United States)

    Blumrich, Matthias A.; Chen, Dong; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Ohmacht, Martin; Salapura, Velentina; Vranas, Pavlos

    2014-06-17

    An apparatus and method for tracking coherence event signals transmitted in a multiprocessor system. The apparatus comprises a coherence logic unit, each unit having a plurality of queue structures with each queue structure associated with a respective sender of event signals transmitted in the system. A timing circuit associated with a queue structure controls enqueuing and dequeuing of received coherence event signals, and, a counter tracks a number of coherence event signals remaining enqueued in the queue structure and dequeued since receipt of a timestamp signal. A counter mechanism generates an output signal indicating that all of the coherence event signals present in the queue structure at the time of receipt of the timestamp signal have been dequeued. In one embodiment, the timestamp signal is asserted at the start of a memory synchronization operation and, the output signal indicates that all coherence events present when the timestamp signal was asserted have completed. This signal can then be used as part of the completion condition for the memory synchronization operation.

  11. Reliability-based server selection for heterogeneous VANETs

    OpenAIRE

    Seyedali Hosseininezhad; Victor C. M. Leung

    2011-01-01

    Heterogeneous wireless networks are capable of providing customers with better services while service providers can offer more applications to more customers with lower costs. To provide services, some applications rely on existing servers in the network. In a vehicular ad-hoc network (VANET) some mobile nodes may function as servers. Due to high mobility of nodes and short lifetime of links, server-to-client and server-to-server communications become challenging. In this paper we propose to ...

  12. DelPhiPKa web server: predicting pKa of proteins, RNAs and DNAs.

    Science.gov (United States)

    Wang, Lin; Zhang, Min; Alexov, Emil

    2016-02-15

    A new pKa prediction web server is released, which implements DelPhi Gaussian dielectric function to calculate electrostatic potentials generated by charges of biomolecules. Topology parameters are extended to include atomic information of nucleotides of RNA and DNA, which extends the capability of pKa calculations beyond proteins. The web server allows the end-user to protonate the biomolecule at particular pH based on calculated pKa values and provides the downloadable file in PQR format. Several tests are performed to benchmark the accuracy and speed of the protocol. The web server follows a client-server architecture built on PHP and HTML and utilizes DelPhiPKa program. The computation is performed on the Palmetto supercomputer cluster and results/download links are given back to the end-user via http protocol. The web server takes advantage of MPI parallel implementation in DelPhiPKa and can run a single job on up to 24 CPUs. The DelPhiPKa web server is available at http://compbio.clemson.edu/pka_webserver. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  13. Mixed gated/exhaustive service in a polling model with priorities

    NARCIS (Netherlands)

    Boon, M.A.A.; Adan, I.J.B.F.

    2008-01-01

    In this paper we consider a single-server polling system with switch-over times. We introduce a new service discipline, mixed gated/exhaustive service, that can be used for queues with two types of customers: high and low priority customers. At the beginning of a visit of the server to such a queue,

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

    Science.gov (United States)

    Alexandrescu, Liviu

    2017-02-01

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

  15. Terminal appointment system design by non-stationary M(t)/E /c(t) queueing model and genetic algorithm

    DEFF Research Database (Denmark)

    Chen, G.; Govindan, Kannan; Yang, Z.-Z.

    2013-01-01

    Long truck queue is a common problem at big marine container terminals, where the resources and equipment are usually scheduled to serve ships prior to trucks. To reduce truck queues, some container terminals adopt terminal appointment system (TAS) to manage truck arrivals. This paper addresses t...

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    We designed a queue-based model, and investigated which parameters are of importance when predicting stroke outcome. Medical record forms have been collected for 57 ischemic stroke patients, including medical history and vital sign measurement along with neurological scores for the first twenty-f......, where outcome for patients were 36.75 ± 10.99. The queue-based model integrating multiple linear regression shows promising results for automatic selection of significant medically relevant parameters.......-four hours of admission. The importance of each parameter is identified using multiple regression combined with a circular queue to iteratively fit outcome. Out of 39 parameters, the model isolated 14 which combined could estimate outcome with a root mean square error of 1.69 on the Scandinavian Stroke Scale...

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

    Directory of Open Access Journals (Sweden)

    Dhruba Das

    2015-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Nguyen Kim Quoc

    2015-08-01

    Full Text Available The bottleneck control by active queue management mechanisms at network nodes is essential. In recent years, some researchers have used fuzzy argument to improve the active queue management mechanisms to enhance the network performance. However, the projects using the fuzzy controller depend heavily on professionals and their parameters cannot be updated according to changes in the network, so the effectiveness of this mechanism is not high. Therefore, we propose a model combining the fuzzy controller with neural network (FNN to overcome the limitations above. Results of the training of the neural networks will find the optimal parameters for the adaptive fuzzy controller well to changes of the network. This improves the operational efficiency of the active queue management mechanisms at network nodes.

  19. On the Discrete-Time Geo/G/1 Queue with Vacations in Random Environment

    Directory of Open Access Journals (Sweden)

    Jianjun Li

    2016-01-01

    Full Text Available A discrete-time Geo/G/1 queue with vacations in random environment is analyzed. Using the method of supplementary variable, we give the probability generating function (PGF of the stationary queue length distribution at arbitrary epoch. The PGF of the stationary sojourn time distribution is also derived. And we present the various performance measures such as mean number of customers in the system, mean length of the type-i cycle, and mean time that the system resides in phase 0. In addition, we show that the M/G/1 queue with vacations in random environment can be approximated by its discrete-time counterpart. Finally, we present some special cases of the model and numerical examples.

  20. Installing and Testing a Server Operating System

    Directory of Open Access Journals (Sweden)

    Lorentz JÄNTSCHI

    2003-08-01

    Full Text Available The paper is based on the experience of the author with the FreeBSD server operating system administration on three servers in use under academicdirect.ro domain.The paper describes a set of installation, preparation, and administration aspects of a FreeBSD server.First issue of the paper is the installation procedure of FreeBSD operating system on i386 computer architecture. Discussed problems are boot disks preparation and using, hard disk partitioning and operating system installation using a existent network topology and a internet connection.Second issue is the optimization procedure of operating system, server services installation, and configuration. Discussed problems are kernel and services configuration, system and services optimization.The third issue is about client-server applications. Using operating system utilities calls we present an original application, which allows displaying the system information in a friendly web interface. An original program designed for molecular structure analysis was adapted for systems performance comparisons and it serves for a discussion of Pentium, Pentium II and Pentium III processors computation speed.The last issue of the paper discusses the installation and configuration aspects of dial-in service on a UNIX-based operating system. The discussion includes serial ports, ppp and pppd services configuration, ppp and tun devices using.

  1. MISTIC: Mutual information server to infer coevolution.

    Science.gov (United States)

    Simonetti, Franco L; Teppa, Elin; Chernomoretz, Ariel; Nielsen, Morten; Marino Buslje, Cristina

    2013-07-01

    MISTIC (mutual information server to infer coevolution) is a web server for graphical representation of the information contained within a MSA (multiple sequence alignment) and a complete analysis tool for Mutual Information networks in protein families. The server outputs a graphical visualization of several information-related quantities using a circos representation. This provides an integrated view of the MSA in terms of (i) the mutual information (MI) between residue pairs, (ii) sequence conservation and (iii) the residue cumulative and proximity MI scores. Further, an interactive interface to explore and characterize the MI network is provided. Several tools are offered for selecting subsets of nodes from the network for visualization. Node coloring can be set to match different attributes, such as conservation, cumulative MI, proximity MI and secondary structure. Finally, a zip file containing all results can be downloaded. The server is available at http://mistic.leloir.org.ar. In summary, MISTIC allows for a comprehensive, compact, visually rich view of the information contained within an MSA in a manner unique to any other publicly available web server. In particular, the use of circos representation of MI networks and the visualization of the cumulative MI and proximity MI concepts is novel.

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

    Directory of Open Access Journals (Sweden)

    Florin-Catalin ENACHE

    2015-10-01

    Full Text Available The growing character of the cloud business has manifested exponentially in the last 5 years. The capacity managers need to concentrate on a practical way to simulate the random demands a cloud infrastructure could face, even if there are not too many mathematical tools to simulate such demands.This paper presents an introduction into the most important stochastic processes and queueing theory concepts used for modeling computer performance. Moreover, it shows the cases where such concepts are applicable and when not, using clear programming examples on how to simulate a queue, and how to use and validate a simulation, when there are no mathematical concepts to back it up.

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

    DEFF Research Database (Denmark)

    Saffari, Mohammad; Asmussen, Søren; Haji, Rasoul

    We consider an M/M/1 queueing system with inventory under the (r,Q) policy and with lost sales, in which demands occur according to a Poisson process and service times are exponentially distributed. All arriving customers during stockout are lost. We derive the stationary distributions of the joint...... queue length (number of customers in the system) and on-hand inventory when lead times are random variables and can take various distributions. The derived stationary distributions are used to formulate long-run average performance measures and cost functions in some numerical examples....

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

    Directory of Open Access Journals (Sweden)

    Ahn Boo Yong

    1999-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Parminderjeet Singh

    2014-12-01

    Full Text Available The comparison of throughput for TEAR (TCP emulation at receivers and TFRC TCP friendly rate control in MANETs is done with varying Active queue Management Techniques. The analysis reveals that for bandwidth constraint links, TEAR and TFRC perform far better than normal traffic propagation through TCP. In case of TEAR, the processing and route congestion algorithm load is shared by the receiver resulting in lesser load at the transmitters. In TFRC the TCP traffic is propagated via an algorithm to curb acknowledgement congestions. The effect of these two techniques is monitored on Droptail and RED, two of the most common Active Queue Management Techniques.

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

    Science.gov (United States)

    Saini, Sanju; Saini, J. S.

    2012-11-01

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

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

    Directory of Open Access Journals (Sweden)

    Zhao Yi Fan

    2016-01-01

    Full Text Available paper presents a new use of double queues asymmetric gated service polling system in the intelligent traffic light control system.Usually there are more vehicles in main road than minor road,so there are more green light time be needed in the main road.From the computer simulation and theory analysis,we can find that the application of double queues asymmetric gated service polling theory in intelligent traffic system can balance intersections load and set suitable passing time for vehicles to assure the roads open.

  8. An efficient biometric and password-based remote user authentication using smart card for Telecare Medical Information Systems in multi-server environment.

    Science.gov (United States)

    Maitra, Tanmoy; Giri, Debasis

    2014-12-01

    The medical organizations have introduced Telecare Medical Information System (TMIS) to provide a reliable facility by which a patient who is unable to go to a doctor in critical or urgent period, can communicate to a doctor through a medical server via internet from home. An authentication mechanism is needed in TMIS to hide the secret information of both parties, namely a server and a patient. Recent research includes patient's biometric information as well as password to design a remote user authentication scheme that enhances the security level. In a single server environment, one server is responsible for providing services to all the authorized remote patients. However, the problem arises if a patient wishes to access several branch servers, he/she needs to register to the branch servers individually. In 2014, Chuang and Chen proposed an remote user authentication scheme for multi-server environment. In this paper, we have shown that in their scheme, an non-register adversary can successfully logged-in into the system as a valid patient. To resist the weaknesses, we have proposed an authentication scheme for TMIS in multi-server environment where the patients can register to a root telecare server called registration center (RC) in one time to get services from all the telecare branch servers through their registered smart card. Security analysis and comparison shows that our proposed scheme provides better security with low computational and communication cost.

  9. Manajemen Server Jaringan Komputer Berbasis Teknologi Virtualisasi Menggunakan Proxmox

    Directory of Open Access Journals (Sweden)

    Hendi Suhendi

    2017-04-01

    Abstract Based on research conducted by the authors, there are two server machines that have less resources well as using personal computer with a specification is not for the server, so it can not serve clients well. In addition, there is no central server data storage for data sharing. The solution to the problem is to replace the server resources with one unit of PC servers with high specification. And because there are two servers, the method used for this problem is Virtualization Technology. All machines are built in server virtualization technology by using Proxmox. Proxmox is open source software for running Virtual Machine. With proxmox can minimize the use of hardware and ease in maintenance due to using the Web Base Management for the organization. And with the construction of a data center server for data storage and sharing of data values.   Keywords: Virtualization, Proxmox, Server.

  10. Measurement of Energy Performances for General-Structured Servers

    Science.gov (United States)

    Liu, Ren; Chen, Lili; Li, Pengcheng; Liu, Meng; Chen, Haihong

    2017-11-01

    Energy consumption of servers in data centers increases rapidly along with the wide application of Internet and connected devices. To improve the energy efficiency of servers, voluntary or mandatory energy efficiency programs for servers, including voluntary label program or mandatory energy performance standards have been adopted or being prepared in the US, EU and China. However, the energy performance of servers and testing methods of servers are not well defined. This paper presents matrices to measure the energy performances of general-structured servers. The impacts of various components of servers on their energy performances are also analyzed. Based on a set of normalized workload, the author proposes a standard method for testing energy efficiency of servers. Pilot tests are conducted to assess the energy performance testing methods of servers. The findings of the tests are discussed in the paper.

  11. The ProFunc Function Prediction Server.

    Science.gov (United States)

    Laskowski, Roman A

    2017-01-01

    The ProFunc web server is a tool for helping identify the function of a given protein whose 3D coordinates have been experimentally determined or homology modeled. It uses a cocktail of both sequence- and structure-based methods to identify matches to other proteins that may, in turn, suggest the query protein's most likely function. The server was originally developed to aid the worldwide structural genomics effort at the start of the millennium. It accepts a file containing the protein's 3D coordinates in PDB format, and, when processing is complete, sends an email containing a link to the password-protected result pages. The results include an at-a-glance summary, as well as separate pages containing more detailed analyses. The server can be found at: http://www.ebi.ac.uk/thornton-srv/databases/profunc .

  12. ProTSAV: A protein tertiary structure analysis and validation server.

    Science.gov (United States)

    Singh, Ankita; Kaushik, Rahul; Mishra, Avinash; Shanker, Asheesh; Jayaram, B

    2016-01-01

    Quality assessment of predicted model structures of proteins is as important as the protein tertiary structure prediction. A highly efficient quality assessment of predicted model structures directs further research on function. Here we present a new server ProTSAV, capable of evaluating predicted model structures based on some popular online servers and standalone tools. ProTSAV furnishes the user with a single quality score in case of individual protein structure along with a graphical representation and ranking in case of multiple protein structure assessment. The server is validated on ~64,446 protein structures including experimental structures from RCSB and predicted model structures for CASP targets and from public decoy sets. ProTSAV succeeds in predicting quality of protein structures with a specificity of 100% and a sensitivity of 98% on experimentally solved structures and achieves a specificity of 88%and a sensitivity of 91% on predicted protein structures of CASP11 targets under 2Å.The server overcomes the limitations of any single server/method and is seen to be robust in helping in quality assessment. ProTSAV is freely available at http://www.scfbio-iitd.res.in/software/proteomics/protsav.jsp. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Professional Microsoft SQL Server 2012 Integration Services

    CERN Document Server

    Knight, Brian; Moss, Jessica M; Davis, Mike; Rock, Chris

    2012-01-01

    An in-depth look at the radical changes to the newest release of SISS Microsoft SQL Server 2012 Integration Services (SISS) builds on the revolutionary database product suite first introduced in 2005. With this crucial resource, you will explore how this newest release serves as a powerful tool for performing extraction, transformation, and load operations (ETL). A team of SQL Server experts deciphers this complex topic and provides detailed coverage of the new features of the 2012 product release. In addition to technical updates and additions, the authors present you with a new set of SISS b

  14. SQL Server Management Studio Express 02

    OpenAIRE

    Suárez Cueto, Armando; Moreda Pozo, Paloma; Mingot Latorre, Iván

    2013-01-01

    Segunda parte de los primeros pasos en el uso de este programa cliente de acceso y administración de SQL Server. Este cliente, en su versión Express, es gratuito. El ejemplo del vídeo se conecta con un servidor remoto SQL Server 2008 R2. Modificar tablas. Exportar definiciones del esquema. Resultados a cuadrícula o texto. Guardar resultados. Captura: BB Flashback Express Recorder 4.1.0. Edición vídeo: Adobe Premiere Pro CS5.5. Edición audio: Adobe Audition CS5.5.

  15. Saving Money and Time with Virtual Server

    CERN Document Server

    Sanders, Chris

    2006-01-01

    Microsoft Virtual Server 2005 consistently proves to be worth its weight in gold, with new implementations thought up every day. With this product now a free download from Microsoft, scores of new users are able to experience what the power of virtualization can do for their networks. This guide is aimed at network administrators who are interested in ways that Virtual Server 2005 can be implemented in their organizations in order to save money and increase network productivity. It contains information on setting up a virtual network, virtual consolidation, virtual security, virtual honeypo

  16. Optimizing the NASA Technical Report Server

    Science.gov (United States)

    Nelson, Michael L.; Maa, Ming-Hokng

    1996-01-01

    The NASA Technical Report Server (NTRS), a World Wide Web report distribution NASA technical publications service, is modified for performance enhancement, greater protocol support, and human interface optimization. Results include: Parallel database queries, significantly decreasing user access times by an average factor of 2.3; access from clients behind firewalls and/ or proxies which truncate excessively long Uniform Resource Locators (URLs); access to non-Wide Area Information Server (WAIS) databases and compatibility with the 239-50.3 protocol; and a streamlined user interface.

  17. Instant Hyper-v Server Virtualization starter

    CERN Document Server

    Eguibar, Vicente Rodriguez

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks.The approach would be in a tutorial manner that will guide the users in an orderly manner toward virtualization.This book is conceived for system administrator and advanced PC enthusiasts who want to venture into the virtualization world. Although this book goes from scratch up, knowledge on server Operative Systems, LAN and networking has to be in place. Having a good background on server administration is desirable, including networking service

  18. Windows Server® 2008 Inside Out

    CERN Document Server

    Stanek, William R

    2009-01-01

    Learn how to conquer Windows Server 2008-from the inside out! Designed for system administrators, this definitive resource features hundreds of timesaving solutions, expert insights, troubleshooting tips, and workarounds for administering Windows Server 2008-all in concise, fast-answer format. You will learn how to perform upgrades and migrations, automate deployments, implement security features, manage software updates and patches, administer users and accounts, manage Active Directory® directory services, and more. With INSIDE OUT, you'll discover the best and fastest ways to perform core a

  19. Instant Team Foundation Server 2012 and Project Server 2010 integration how-to

    CERN Document Server

    Gauvin, Gary P

    2013-01-01

    Filled with practical, step-by-step instructions and clear explanations for the most important and useful tasks. Get the job done and learn as you go. A how-To book with practical recipes accompanied with rich screenshots for easy comprehension.The How-to style is a very practical book which will take the reader through the process of garnering a basic understanding of TFS and Project Server with practical tutorials and recipes.This book is for users who want to integrate TFS 2012 and Project Server 2010. Readers are expected to know some basic Windows Server commands and account management, a

  20. RANCANG BANGUN PERANGKAT LUNAK MANAJEMEN DATABASE SQL SERVER BERBASIS WEB

    Directory of Open Access Journals (Sweden)

    Muchammad Husni

    2005-01-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Microsoft SQL Server merupakan aplikasi desktop database server yang bersifat client/server, karena memiliki komponen client, yang  berfungsi menampilkan dan memanipulasi data; serta komponen server yang berfungsi menyimpan, memanggil, dan mengamankan database. Operasi-operasi manajemen semua server database dalam jaringan dilakukan administrator database dengan menggunakan tool administratif utama SQL Server yang bernama Enterprise Manager. Hal ini mengakibatkan administrator database hanya bisa  melakukan operasi-operasi tersebut di komputer yang telah diinstalasi Microsoft SQL Server. Pada penelitian ini, dirancang suatu aplikasi berbasis web dengan menggunakan ASP.Net untuk melakukan pengaturan database server. Aplikasi ini menggunakan ADO.NET yang memanfaatkan Transact-SQL dan stored procedure pada server untuk melakukan operasi-operasi manajemen database pada suatu server database SQL, dan menampilkannya ke dalam web. Administrator database bisa menjalankan aplikasi berbasis web tersebut dari komputer mana saja pada jaringan dan melakukan koneksi ke server database SQL dengan menggunakan web browser. Dengan demikian memudahkan administrator melakukan tugasnya tanpa harus menggunakan komputer server.   Kata Kunci : Transact-SQL, ASP.Net, ADO.NET, SQL Server

  1. Mastering SQL Server 2014 data mining

    CERN Document Server

    Bassan, Amarpreet Singh

    2014-01-01

    If you are a developer who is working on data mining for large companies and would like to enhance your knowledge of SQL Server Data Mining Suite, this book is for you. Whether you are brand new to data mining or are a seasoned expert, you will be able to master the skills needed to build a data mining solution.

  2. Solarwinds Server & Application Monitor deployment and administration

    CERN Document Server

    Brant, Justin

    2013-01-01

    A concise and practical guide to using SolarWinds Server & Application Monitor.If you are an IT professionals ranging from an entry-level technician to a more advanced network or system administrator who is new to network monitoring services and/or SolarWinds SAM, this book is ideal for you.

  3. Creating a Data Warehouse using SQL Server

    DEFF Research Database (Denmark)

    Sørensen, Jens Otto; Alnor, Karl

    1999-01-01

    In this paper we construct a Star Join Schema and show how this schema can be created using the basic tools delivered with SQL Server 7.0. Major objectives are to keep the operational database unchanged so that data loading can be done with out disturbing the business logic of the operational...... database....

  4. The accuracy of protein structure alignment servers

    Directory of Open Access Journals (Sweden)

    Naeem Aslam

    2016-03-01

    Conclusion: Overall none of the structural alignment servers showed 100% success rate. Studies of overall performance, effect of mainly alpha and effect of mainly beta showed consistent performance. CE, DALI, FatCat and PhyreStorm showed more than 90% success rate.

  5. Client/Server Architecture Promises Radical Changes.

    Science.gov (United States)

    Freeman, Grey; York, Jerry

    1991-01-01

    This article discusses the emergence of the client/server paradigm for the delivery of computer applications, its emergence in response to the proliferation of microcomputers and local area networks, the applicability of the model in academic institutions, and its implications for college campus information technology organizations. (Author/DB)

  6. Server-side Statistics Scripting in PHP

    Directory of Open Access Journals (Sweden)

    Jan de Leeuw

    1997-06-01

    Full Text Available On the UCLA Statistics WWW server there are a large number of demos and calculators that can be used in statistics teaching and research. Some of these demos require substantial amounts of computation, others mainly use graphics. These calculators and demos are implemented in various different ways, reflecting developments in WWW based computing. As usual, one of the main choices is between doing the work on the client-side (i.e. in the browser or on the server-side (i.e. on our WWW server. Obviously, client-side computation puts fewer demands on the server. On the other hand, it requires that the client downloads Java applets, or installs plugins and/or helpers. If JavaScript is used, client-side computations will generally be slow. We also have to assume that the client is installed properly, and has the required capabilities. Requiring too much on the client-side has caused browsing machines such as Netscape Communicator to grow beyond all reasonable bounds, both in size and RAM requirements. Moreover requiring Java and JavaScript rules out such excellent browsers as Lynx or Emacs W3. For server-side computing, we can configure the server and its resources ourselves, and we need not worry about browser capabilities and configuration. Nothing needs to be downloaded, except the usual HTML pages and graphics. In the same way as on the client side, there is a scripting solution, where code is interpreted, or a ob ject-code solution using compiled code. For the server-side scripting, we use embedded languages, such as PHP/FI. The scripts in the HTML pages are interpreted by a CGI program, and the output of the CGI program is send to the clients. Of course the CGI program is compiled, but the statistics procedures will usually be interpreted, because PHP/FI does not have the appropriate functions in its scripting language. This will tend to be slow, because embedded languages do not deal efficiently with loops and similar constructs. Thus a first

  7. Client/server power attracts healthcare markets.

    Science.gov (United States)

    Kellerhals, S; Wheeler, M F; Dunbar, C; Lee, S

    1993-08-01

    Client/server architecture has become the darling of I/S professionals. The intelligence is spread among several processors, creating enormous flexibility. But are C/S systems easier, cheaper and faster than the good old mainframe? Not quite yet.

  8. Implementing bioinformatic workflows within the bioextract server

    Science.gov (United States)

    Computational workflows in bioinformatics are becoming increasingly important in the achievement of scientific advances. These workflows typically require the integrated use of multiple, distributed data sources and analytic tools. The BioExtract Server (http://bioextract.org) is a distributed servi...

  9. Microsoft Exchange Server PowerShell cookbook

    CERN Document Server

    Andersson, Jonas

    2015-01-01

    This book is for messaging professionals who want to build real-world scripts with Windows PowerShell 5 and the Exchange Management Shell. If you are a network or systems administrator responsible for managing and maintaining Exchange Server 2013, you will find this highly useful.

  10. Queueing networks with string transitions of mixed vector additions and vector removals

    NARCIS (Netherlands)

    Boucherie, Richardus J.; Chao, Xiuli

    2001-01-01

    Product form queueing networks with string transitions have been studied in the literature as a model incorporating several features of the existing networks. That model includes state-dependent transition rates at the cost of a restrictive form of the string transitions:First a sequence of

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

    Directory of Open Access Journals (Sweden)

    Ganesh Patil

    2011-06-01

    Full Text Available There are many factors that are important in the design of queue management schemes for routers in the Internet: for example, queuing delay, link utilization, packet loss, energy consumption and the impact of router buffer size. By considering a fluid model for the congestion avoidance phase of Additive Increase Multiplicative Decrease (AIMD TCP, in a small buffer regime, we argue that stability should also be a desirable feature for network performance. The queue management schemes we study are Drop Tail and Random Early Detection (RED. For Drop Tail, the analytical arguments are based on local stability and bifurcation theory. As the buffer size acts as a bifurcation parameter, variations in it can readily lead to the emergence of limit cycles. We then present NS2 simulations to study the effect of changing buffer size on queue dynamics, utilization, window size and packet loss for three different flow scenarios. The simulations corroborate the analysis which highlights that performance is coupled with the notion of stability. Our work suggests that, in a small buffer regime, a simple Drop Tail queue management serves to enhance stability and appears preferable to the much studied RED scheme.

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

    NARCIS (Netherlands)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Alexander N. Dudin

    2000-01-01

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

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

    NARCIS (Netherlands)

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

    2007-01-01

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

  15. 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.

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

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

    NARCIS (Netherlands)

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

    1997-01-01

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

  18. A new, analysis-based, change of measure for tandem queues

    NARCIS (Netherlands)

    de Boer, Pieter-Tjerk; Scheinhardt, Willem R.W.

    In this paper, we introduce a simple analytical approximation for the overflow probability of a two-node tandem queue. From this, we derive a change of measure, which turns out to have good performance in almost the entire parameter space. The form of our new change of measure sheds an interesting

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

    NARCIS (Netherlands)

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

    2000-01-01

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

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

    DEFF Research Database (Denmark)

    Breinbjerg, Jesper

    2017-01-01

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

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

    Science.gov (United States)

    Walden, R. S.; Rouse, W. B.

    1977-01-01

    Allocation of decision making responsibility between pilot and computer is considered and a flight management task, designed for the study of pilot-computer interaction, is discussed. A queueing theory model of pilot decision making in this multi-task, control and monitoring situation is presented. An experimental investigation of pilot decision making and the resulting model parameters are discussed.

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

    Science.gov (United States)

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

    2017-10-01

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

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

    Science.gov (United States)

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

    2013-09-01

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

  4. A queueing-theoretic analysis of the threshold-based exhaustive data-backup scheduling policy

    Science.gov (United States)

    Claeys, Dieter; Dorsman, Jan-Pieter; Saxena, Apoorv; Walraevens, Joris; Bruneel, Herwig

    2017-07-01

    We analyse the threshold-based exhaustive data backup scheduling mechanism by means of a queueing-theoretic approach. Data packets that have not yet been backed up are modelled by customers waiting for service (back-up). We obtain the probability generating function of the system content (backlog size) at random slot boundaries in steady state.

  5. Active Methodologies in a Queueing Systems Course for Telecommunication Engineering Studies

    Science.gov (United States)

    Garcia, J.; Hernandez, A.

    2010-01-01

    This paper presents the results of a one-year experiment in incorporating active methodologies in a Queueing Systems course as part of the Telecommunication Engineering degree at the University of Zaragoza, Spain, during the period of adaptation to the European Higher Education Area. A problem-based learning methodology has been introduced, and…

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

    NARCIS (Netherlands)

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

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

  7. ModFOLD6: an accurate web server for the global and local quality estimation of 3D protein models.

    Science.gov (United States)

    Maghrabi, Ali H A; McGuffin, Liam J

    2017-07-03

    Methods that reliably estimate the likely similarity between the predicted and native structures of proteins have become essential for driving the acceptance and adoption of three-dimensional protein models by life scientists. ModFOLD6 is the latest version of our leading resource for Estimates of Model Accuracy (EMA), which uses a pioneering hybrid quasi-single model approach. The ModFOLD6 server integrates scores from three pure-single model methods and three quasi-single model methods using a neural network to estimate local quality scores. Additionally, the server provides three options for producing global score estimates, depending on the requirements of the user: (i) ModFOLD6_rank, which is optimized for ranking/selection, (ii) ModFOLD6_cor, which is optimized for correlations of predicted and observed scores and (iii) ModFOLD6 global for balanced performance. The ModFOLD6 methods rank among the top few for EMA, according to independent blind testing by the CASP12 assessors. The ModFOLD6 server is also continuously automatically evaluated as part of the CAMEO project, where significant performance gains have been observed compared to our previous server and other publicly available servers. The ModFOLD6 server is freely available at: http://www.reading.ac.uk/bioinf/ModFOLD/. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  8. Efficient Server-Aided 2PC for Mobile Phones

    Directory of Open Access Journals (Sweden)

    Mohassel Payman

    2016-04-01

    Full Text Available Secure Two-Party Computation (2PC protocols allow two parties to compute a function of their private inputs without revealing any information besides the output of the computation. There exist low cost general-purpose protocols for semi-honest parties that can be efficiently executed even on smartphones. However, for the case of malicious parties, current 2PC protocols are significantly less efficient, limiting their use to more resourceful devices. In this work we present an efficient 2PC protocol that is secure against malicious parties and is light enough to be used on mobile phones. The protocol is an adaptation of the protocol of Nielsen et al. (Crypto, 2012 to the Server-Aided setting, a natural relaxation of the plain model for secure computation that allows the parties to interact with a server (e.g., a cloud who is assumed not to collude with any of the parties. Our protocol has two stages: In an offline stage - where no party knows which function is to be computed, nor who else is participating - each party interacts with the server and downloads a file. Later, in the online stage, when two parties decide to execute a 2PC together, they can use the files they have downloaded earlier to execute the computation with cost that is lower than the currently best semi-honest 2PC protocols. We show an implementation of our protocol for Android mobile phones, discuss several optimizations and report on its evaluation for various circuits. For example, the online stage for evaluating a single AES circuit requires only 2.5 seconds and can be further reduced to 1 second (amortized time with multiple executions.

  9. Server virtualization management of corporate network with hyper-v

    OpenAIRE

    Kovalenko, Taras

    2012-01-01

    On a paper main tasks and problems of server virtualization are considerate. Practical value of virtualization in a corporate network, advantages and disadvantages of application of server virtualization are also considerate.

  10. Il nuovo server per il calcolo parallelo al CILEA: HP 9000 Enterprise Server K580

    OpenAIRE

    Bonini, Francesca

    1999-01-01

    In questo articolo è presentato il nuovo server ad alte prestazioni, per il calcolo parallelo, disponibile al Cilea. In particolare, viene fornita una breve descrizione dei pacchetti software disponibili, della configurazione e delle modalità di utilizzo della macchina.

  11. A proposal for improving data center management through strategic implementation of Server virtualization technology to support Malaysian Nuclear Agency's activities

    International Nuclear Information System (INIS)

    Mohamad Safuan Sulaiman; Abdul Muin Abdul Rahman; Raja Murzaferi Raja Moktar; Saaidi Ismail

    2010-01-01

    Management of servers in Nuclear Malaysia's data center poses a big challenge to IT Center as well as to the general management. Traditional server management techniques have been used to provide reliable and continuous support for the ever increasing services and applications demanded by researchers and the other staffs of Nuclear Malaysia. Data centers are cost centers which need logistical support such as electricity, air conditioning, room space, manpower and other resources. To save cost and comply with Green Technology while maintaining or improving the level of services, a new concept called server virtualization is proposed and a feasibility study of this technology has been initiated to explore its potential to accommodate IT centers ever demanding services while reducing the need for such logistical supports, hence adhering to the Green IT concept. Server virtualization is a new technology where a single high performance physical server can host multiple high processing services, and different types operating systems with different hardware and software requirements which are traditionally performed by multiple server machines. This paper briefly explains server virtualization concepts, tools and techniques and proposes an implementation strategy of the technology for Nuclear Malaysia's data center. (author)

  12. Reliability-based server selection for heterogeneous VANETs

    Directory of Open Access Journals (Sweden)

    Seyedali Hosseininezhad

    2011-09-01

    Full Text Available Heterogeneous wireless networks are capable of providing customers with better services while service providers can offer more applications to more customers with lower costs. To provide services, some applications rely on existing servers in the network. In a vehicular ad-hoc network (VANET some mobile nodes may function as servers. Due to high mobility of nodes and short lifetime of links, server-to-client and server-to-server communications become challenging. In this paper we propose to enhance the performance of server selection by taking link reliability into consideration in the server selection mechanism, thereby avoiding extra client-to-server hand-offs and reducing the need of server-to-server synchronization. As a case study we focus on location management service in a heterogeneous VANET. We provide a routing algorithm for transactions between location servers and mobile nodes. We assume that location servers are vehicles equipped with at least one long- range and one short-range radio interfaces, whereas regular nodes (clients are only equipped with a short-range radio interface. The primary goal of our design is to minimize hand-offs between location servers while limiting the delays of location updates. Taking advantage of vehicle mobility patterns, we propose a mobility-aware server selection scheme and show that it can reduce the number of hand-offs and yet avoid large delays during location updates. We present simulation results to show that proposed scheme significantly lowers the costs of signaling and rate of server hand-offs by increasing the connection lifetimes between clients and servers.

  13. Web server's reliability improvements using recurrent neural networks

    DEFF Research Database (Denmark)

    Madsen, Henrik; Albu, Rǎzvan-Daniel; Felea, Ioan

    2012-01-01

    In this paper we describe an interesting approach to error prediction illustrated by experimental results. The application consists of monitoring the activity for the web servers in order to collect the specific data. Predicting an error with severe consequences for the performance of a server (t...... usage, network usage and memory usage. We collect different data sets from monitoring the web server's activity and for each one we predict the server's reliability with the proposed recurrent neural network. © 2012 Taylor & Francis Group...

  14. The Client Server Design of the Gemini Data Handling System

    Science.gov (United States)

    Hill, Norman; Gaudet, Séverin; Dunn, Jennifer; Jaeger, Shannon; Cockayne, Steve

    The Gemini Telescopes Data Handling System (DHS) developed by the Canadian Astronomy Data Centre (CADC) has diverse requirements to support the operation of the Gemini telescopes. The DHS is implemented as a group of servers, where each performs separate functions. The servers use a client server model to communicate between themselves and with other Gemini software systems. This paper describes the client server model of the Gemini Data Handling System.

  15. Client-server architecture applied to system automation radioactivity sampling in atmosphere

    Science.gov (United States)

    Hubbard, C. W.; McKinnon, A. D.

    1997-06-01

    Control software for an automated particulate air sampler is described. The software is divided into a number of small, cooperating server processes, each of which is responsible for the control of a particular device or subsystem. For each process, an effort was made to isolate the details of the underlying device or subsystem from the server interface. This made it possible to change the hardware without making changes to any of the server's client processes. A single supervisor process is responsible for overall system control. The design of the control algorithm was facilitated by employing a state machine model. Such a model is easy to study, easy to modify, and provides a clear understanding of the control mechanism to programmers and non-programmers alike. A state machine library was developed which greatly eased the task of implementing the design and ensured that the control algorithm detailed by the state machine model was the same algorithm that was actually employed.

  16. Perancangan Sistem Proxy Server Menggunakan Protokol WCCPv2 dengan Konfigurasi Multi Router

    Directory of Open Access Journals (Sweden)

    Fatah Mumtaz Al'Ala

    2016-04-01

    Full Text Available Numbers of internet users are increasing incredibly fast. Ideally, this increasing numbers of users are also supported by capacity uplift, in this case an increase in bandwidth to maintain the standard services that received by the users. However, increasing the bandwidth not always becomes the first option since it is quite expensive. Implementing proxy server as content/cache engine is the other option available. It will cache the content that user requested and keep it for a while for servicing the other users that will request the same content in the future. WCCP protocol is used to redirect user’s traffic to the proxy server. The standard proxy server configurations are using single router with one or more proxy servers. This thesis is aims to design and implement proxy server system with multi routers configuration. Multi routers configuration is used as a failover mechanism to provide network high availability. It will use HSRP protocol to provide the high availability services. Tests that conducted after implementation shows the increase in transaction and successful transaction by 296% and 284% also a decrease in response time as well as failed transaction by 18% and 99% consecutively. Failover test shows the percentage of packet loss amounted to 31,3% and 26,3% for clients in VLAN 10 and VLAN 20 consecutively. The average time required for clients to reconnect to the internet after router failure is 7 seconds for clients in VLAN 10 and 6 seconds for client in VLAN 20.

  17. KoBaMIN: a knowledge-based minimization web server for protein structure refinement.

    Science.gov (United States)

    Rodrigues, João P G L M; Levitt, Michael; Chopra, Gaurav

    2012-07-01

    The KoBaMIN web server provides an online interface to a simple, consistent and computationally efficient protein structure refinement protocol based on minimization of a knowledge-based potential of mean force. The server can be used to refine either a single protein structure or an ensemble of proteins starting from their unrefined coordinates in PDB format. The refinement method is particularly fast and accurate due to the underlying knowledge-based potential derived from structures deposited in the PDB; as such, the energy function implicitly includes the effects of solvent and the crystal environment. Our server allows for an optional but recommended step that optimizes stereochemistry using the MESHI software. The KoBaMIN server also allows comparison of the refined structures with a provided reference structure to assess the changes brought about by the refinement protocol. The performance of KoBaMIN has been benchmarked widely on a large set of decoys, all models generated at the seventh worldwide experiments on critical assessment of techniques for protein structure prediction (CASP7) and it was also shown to produce top-ranking predictions in the refinement category at both CASP8 and CASP9, yielding consistently good results across a broad range of model quality values. The web server is fully functional and freely available at http://csb.stanford.edu/kobamin.

  18. FPGA-based TESLA cavity SIMCON DOOCS server design, implementation, and application

    Science.gov (United States)

    Rutkowski, Piotr Z.; Romaniuk, Ryszard S.; Pozniak, Krzysztof T.; Jezynski, Tomasz; Pucyk, Piotr D.; Pietrusinski, Michal; Simrock, Stefan

    2004-07-01

    A concise overview of the laboratory solution of the FPGA based TESLA cavity simulator and controller (SIMCON) is presented. The major emphasis is put in this paper on the high level part of the system. There were described the following steps of the system design and realization: solution choice, design of system components, implementing the solutions, introduction of the application, initial analysis of the working application. The paper is a first description of the working DOOCS server for the FPGA based TESLA cavity SIMCON (which is a part of the LLRF subsystem). The data gathered from the work of the DOOCS server promise for the system optimization possibilities. The server will be supplemented with the GUI in the next step of this effort. Throughout the work we will refer to the debated system as to the TESLA SIMCON DOOCS server or in short the "simcon server." The hardware layer of the TESLA cavity SIMCON (to which the designed software refers to) was realized in a single FPGA Virtex chip by Xilinx (XC2V3000 development board by Nallatech).

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

    Directory of Open Access Journals (Sweden)

    Ho Woo Lee

    2003-01-01

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

  20. Client/server approach to image capturing

    Science.gov (United States)

    Tuijn, Chris; Stokes, Earle

    1998-01-01

    The diversity of the digital image capturing devices on the market today is quite astonishing and ranges from low-cost CCD scanners to digital cameras (for both action and stand-still scenes), mid-end CCD scanners for desktop publishing and pre- press applications and high-end CCD flatbed scanners and drum- scanners with photo multiplier technology. Each device and market segment has its own specific needs which explains the diversity of the associated scanner applications. What all those applications have in common is the need to communicate with a particular device to import the digital images; after the import, additional image processing might be needed as well as color management operations. Although the specific requirements for all of these applications might differ considerably, a number of image capturing and color management facilities as well as other services are needed which can be shared. In this paper, we propose a client/server architecture for scanning and image editing applications which can be used as a common component for all these applications. One of the principal components of the scan server is the input capturing module. The specification of the input jobs is based on a generic input device model. Through this model we make abstraction of the specific scanner parameters and define the scan job definitions by a number of absolute parameters. As a result, scan job definitions will be less dependent on a particular scanner and have a more universal meaning. In this context, we also elaborate on the interaction of the generic parameters and the color characterization (i.e., the ICC profile). Other topics that are covered are the scheduling and parallel processing capabilities of the server, the image processing facilities, the interaction with the ICC engine, the communication facilities (both in-memory and over the network) and the different client architectures (stand-alone applications, TWAIN servers, plug-ins, OLE or Apple-event driven

  1. PENGUKURAN KINERJA ROUND-ROBIN SCHEDULER UNTUK LINUX VIRTUAL SERVER PADA KASUS WEB SERVER

    Directory of Open Access Journals (Sweden)

    Royyana Muslim Ijtihadie

    2005-07-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Dengan meningkatnya perkembangan jumlah pengguna internet dan mulai diadopsinya penggunaan internet dalam kehidupan sehari-hari, maka lalulintas data di Internet telah meningkat secara signifikan. Sejalan dengan itu pula beban kerja server-server yang memberikan service di Internet juga mengalami kenaikan yang cukup signifikan. Hal tersebut dapat mengakibatkan suatu server mengalami kelebihan beban pada suatu saat. Untuk mengatasi hal tersebut maka diterapkan skema konfigurasi server cluster menggunakan konsep load balancing. Load balancing server menerapkan algoritma dalam melakukan pembagian tugas. Algoritma round robin telah digunakan pada Linux Virtual Server. Penelitian ini melakukan pengukuran kinerja terhadap Linux Virtual Server yang menggunakan algoritma round robin untuk melakukan penjadwalan pembagian beban terhadap server. Penelitian ini mengukur performa dari sisi client yang mencoba mengakses web server.performa yang diukur adalah jumlah request yang bisa diselesaikan perdetik (request per second, waktu untuk menyelesaikan per satu request, dan   throughput yang dihasilkan. Dari hasil percobaan didapatkan bahwa penggunaan LVS bisa meningkatkan performa, yaitu menaikkan jumlah request per detik

  2. Securing SQL server protecting your database from attackers

    CERN Document Server

    Cherry, Denny

    2015-01-01

    SQL server is the most widely-used database platform in the world, and a large percentage of these databases are not properly secured, exposing sensitive customer and business data to attack. In Securing SQL Server, Third Edition, you will learn about the potential attack vectors that can be used to break into SQL server databases as well as how to protect databases from these attacks. In this book, Denny Cherry - a Microsoft SQL MVP and one of the biggest names in SQL server - will teach you how to properly secure an SQL server database from internal and external threats using best practic

  3. Securing SQL Server Protecting Your Database from Attackers

    CERN Document Server

    Cherry, Denny

    2012-01-01

    Written by Denny Cherry, a Microsoft MVP for the SQL Server product, a Microsoft Certified Master for SQL Server 2008, and one of the biggest names in SQL Server today, Securing SQL Server, Second Edition explores the potential attack vectors someone can use to break into your SQL Server database as well as how to protect your database from these attacks. In this book, you will learn how to properly secure your database from both internal and external threats using best practices and specific tricks the author uses in his role as an independent consultant while working on some of the largest

  4. Experience with Server Self Service Center (S3C)

    CERN Multimedia

    Sucik, J

    2009-01-01

    CERN has a successful experience with running Server Self Service Center (S3C) for virtual server provisioning which is based on Microsoft® Virtual Server 2005. With the introduction of Windows Server 2008 and its built-in hypervisor based virtualization (Hyper-V) there are new possibilities for the expansion of the current service. This paper describes the architecture of the redesigned virtual Server Self Service based on Hyper-V which provides dynamically scalable virtualized resources on demand as needed and outlines the possible implications on the future use of virtual machines at CERN.

  5. Experience with Server Self Service Center (S3C)

    International Nuclear Information System (INIS)

    Sucik, Juraj; Bukowiec, Sebastian

    2010-01-01

    CERN has a successful experience with running Server Self Service Center (S3C) for virtual server provisioning which is based on Microsoft (registered) Virtual Server 2005. With the introduction of Windows Server 2008 and its built-in hypervisor based virtualization (Hyper-V) there are new possibilities for the expansion of the current service. This paper describes the architecture of the redesigned virtual Server Self Service based on Hyper-V which provides dynamically scalable virtualized resources on demand as needed and outlines the possible implications on the future use of virtual machines at CERN.

  6. Energy Servers Deliver Clean, Affordable Power

    Science.gov (United States)

    2010-01-01

    K.R. Sridhar developed a fuel cell device for Ames Research Center, that could use solar power to split water into oxygen for breathing and hydrogen for fuel on Mars. Sridhar saw the potential of the technology, when reversed, to create clean energy on Earth. He founded Bloom Energy, of Sunnyvale, California, to advance the technology. Today, the Bloom Energy Server is providing cost-effective, environmentally friendly energy to a host of companies such as eBay, Google, and The Coca-Cola Company. Bloom's NASA-derived Energy Servers generate energy that is about 67-percent cleaner than a typical coal-fired power plant when using fossil fuels and 100-percent cleaner with renewable fuels.

  7. Client-server modes of GTVGIS

    Science.gov (United States)

    Faust, Nickolas L.; Ribarsky, Bill; Jiang, Frank T. Y.

    2001-08-01

    The capabilities of the Georgia Tech Virtual Geographic Information System (GTVGIS) have been extended recently to fake full advantage of the internal client-server internal structure that we have used in our stand-alone visualization capabilities. Research is underway in the creation of 2 additional client-server modes that will allow GTVGIS capabilities to be accessed by laptop client systems with high quality rendering capability and by very inexpensive lightweight client laptop and possibly hand held computing platforms that need only to support standard web browsers. Interface to large, remote, databases is over IP protocols is necessary for these new GTVGIS modes. This paper describes each mode of GTVGIS and the capabilities and requirements for hardware and software for each of the modes.

  8. Preprint server seeks way to halt plagiarists

    CERN Document Server

    Giles, J

    2003-01-01

    "An unusual case of plagiarism has struck ArXiv, the popular physics preprint server at Cornell University in Ithaca, New York, resulting in the withdrawal of 22 papers...The plagiarism case traces its origins to June 2002, when Yasushi Watanabe, a high-energy physicist at the Tokyo Insitute of Technology, was contacted by Ramy Noboulsi, who said he was a mathematical physicist" (1 page)

  9. SQL Server 2012 reporting services blueprints

    CERN Document Server

    Ribunal, Marlon

    2013-01-01

    Follow the fictional John Kirkland through a series of real-world reporting challenges based on actual business conditions. Use his detailed blueprints to develop your own reports for every requirement.This book is for report developers, data analysts, and database administrators struggling to master the complex world of effective reporting in SQL Server 2012. Knowledge of how data sources and data sets work will greatly help readers to speed through the tutorials.

  10. Reporting with Microsoft SQL Server 2012

    CERN Document Server

    Serra, James

    2014-01-01

    This is a step-by-step tutorial that deals with Microsoft Server 2012 reporting tools:SSRS and Power View.If you are a BI developer, consultant, or architect who wishes to learn how to use SSRS and Power View, and want to understand the best use for each tool, then this book will get you up and running quickly. No prior experience is required with either tool!

  11. Descriptors of server capabilities in China

    DEFF Research Database (Denmark)

    Adeyemi, Oluseyi; Slepniov, Dmitrij; Wæhrens, Brian Vejrum

    China with the huge market potential it possesses is an important issue for subsidiaries of western multinational companies. The objective of this paper is therefore to strengthen researchers’ and practitioners’ perspectives on what are the descriptors of server capabilities. The descriptors...... are relevant to determine subsidiary roles and as an indication of the capabilities required. These descriptors are identified through extensive literature review and validated by case studies of two Danish multinational companies subsidiaries operating in China. They provided the empirical basis...

  12. Implementing a secure client/server application

    Energy Technology Data Exchange (ETDEWEB)

    Kissinger, B.A.

    1994-08-01

    There is an increasing rise in attacks and security breaches on computer systems. Particularly vulnerable are systems that exchange user names and passwords directly across a network without encryption. These kinds of systems include many commercial-off-the-shelf client/server applications. A secure technique for authenticating computer users and transmitting passwords through the use of a trusted {open_quotes}broker{close_quotes} and public/private keys is described in this paper.

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

    Directory of Open Access Journals (Sweden)

    Mina Ghanbarikarekani

    2016-06-01

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

  14. Windows Server 2012 vulnerabilities and security

    Directory of Open Access Journals (Sweden)

    Gabriel R. López

    2015-09-01

    Full Text Available This investigation analyses the history of the vulnerabilities of the base system Windows Server 2012 highlighting the most critic vulnerabilities given every 4 months since its creation until the current date of the research. It was organized by the type of vulnerabilities based on the classification of the NIST. Next, given the official vulnerabilities of the system, the authors show how a critical vulnerability is treated by Microsoft in order to countermeasure the security flaw. Then, the authors present the recommended security approaches for Windows Server 2012, which focus on the baseline software given by Microsoft, update, patch and change management, hardening practices and the application of Active Directory Rights Management Services (AD RMS. AD RMS is considered as an important feature since it is able to protect the system even though it is compromised using access lists at a document level. Finally, the investigation of the state of the art related to the security of Windows Server 2012 shows an analysis of solutions given by third parties vendors, which offer security products to secure the base system objective of this study. The recommended solution given by the authors present the security vendor Symantec with its successful features and also characteristics that the authors considered that may have to be improved in future versions of the security solution.

  15. SPEER-SERVER: a web server for prediction of protein specificity determining sites.

    Science.gov (United States)

    Chakraborty, Abhijit; Mandloi, Sapan; Lanczycki, Christopher J; Panchenko, Anna R; Chakrabarti, Saikat

    2012-07-01

    Sites that show specific conservation patterns within subsets of proteins in a protein family are likely to be involved in the development of functional specificity. These sites, generally termed specificity determining sites (SDS), might play a crucial role in binding to a specific substrate or proteins. Identification of SDS through experimental techniques is a slow, difficult and tedious job. Hence, it is very important to develop efficient computational methods that can more expediently identify SDS. Herein, we present Specificity prediction using amino acids' Properties, Entropy and Evolution Rate (SPEER)-SERVER, a web server that predicts SDS by analyzing quantitative measures of the conservation patterns of protein sites based on their physico-chemical properties and the heterogeneity of evolutionary changes between and within the protein subfamilies. This web server provides an improved representation of results, adds useful input and output options and integrates a wide range of analysis and data visualization tools when compared with the original standalone version of the SPEER algorithm. Extensive benchmarking finds that SPEER-SERVER exhibits sensitivity and precision performance that, on average, meets or exceeds that of other currently available methods. SPEER-SERVER is available at http://www.hpppi.iicb.res.in/ss/.

  16. 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.

  17. Applications of Server Clustering Technology in Sensor Networks

    Science.gov (United States)

    Davis, G.; Foley, S.; Battistuz, B.; Eakins, J.; Vernon, F. L.; Astiz, L.

    2007-12-01

    . - Redundant power and networking connections reduce the chances of a single hardware failure taking down an entire node. - By allowing processing systems to be transferred between cluster nodes, Sun Cluster provides the ability to take servers down for both planned and unplanned maintenance. - This is not a "grid system", there is no single controlling node to fail and take down the entire cluster.

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

    Science.gov (United States)

    Liang, Yaping; Chang, Qing; Li, Xianxu

    2018-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Diwakar Shukla

    2010-01-01

    Full Text Available There are many CPU scheduling algorithms inliterature like FIFO, Round Robin, Shortest-Job-First and so on.The Multilevel-Queue-Scheduling is superior to these due to itsbetter management of a variety of processes. In this paper, aMarkov chain model is used for a general setup of Multilevelqueue-scheduling and the scheduler is assumed to performrandom movement on queue over the quantum of time.Performance of scheduling is examined through a rowdependent data model. It is found that with increasing value of αand d, the chance of system going over the waiting state reduces.At some of the interesting combinations of α and d, it diminishesto zero, thereby, provides us some clue regarding better choice ofqueues over others for high priority jobs. It is found that ifqueue priorities are added in the scheduling intelligently thenbetter performance could be obtained. Data model helpschoosing appropriate preferences.

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

    KAUST Repository

    Tembine, Hamidou

    2014-08-24

    In this paper we examine combined fully distributed payoff and strategy learning (CODIPAS) in a queue-aware access game over a graph. The classical strategic learning analysis relies on vanishing or small learning rate and uses stochastic approximation tool to derive steady states and invariant sets of the underlying learning process. Here, the stochastic approximation framework does not apply due to non-vanishing learning rate. We propose a direct proof of convergence of the process. Interestingly, the convergence time to one of the global optima is almost surely finite and we explicitly characterize the convergence time. We show that pursuit-based CODIPAS learning is much faster than the classical learning algorithms in games. We extend the methodology to coalitional learning and proves a very fast formation of coalitions for queue-aware access games where the action space is dynamically changing depending on the location of the user over a graph.

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

    Science.gov (United States)

    Kempa, Wojciech M.

    2017-12-01

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

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

    Science.gov (United States)

    Hwang, I.-Shyan; Hwang, Bor-Jiunn; Chang, Pen-Ming

    2010-10-01

    Recently, the multimedia services such as IPTV, video conference emerges to be the main traffic source. When UDP coexists with TCP, it induces not only congestion collapse but also unfairness problem. In this paper, a new Active Queue Management (AQM) algorithm, called Traffic Sensitive Active Queue Management (TSAQM), is proposed for providing multimedia services. The TSAQM comprise Dynamic Weight Allocate Scheme (DWAS) and Service Guarantee Scheme (SGS), the purpose of DWAS is to allocate resource with fairness and high end-user utility, and the purpose of SGS is to determine the satisfactory threshold (TH) and threshold region (TR). Several objectives of this proposed scheme include achieving high end-user utility for video service, considering the multicast as well as unicast proprieties to meet inter-class fairness and achieving the QoS requirement by adjusting the thresholds adaptively based on traffic situations.

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

    Directory of Open Access Journals (Sweden)

    Bindu Abraham

    2014-05-01

    Full Text Available In this paper we analyze DAR(1/D/s Queue with Discrete Mittag-Leffler [DML(α] as marginal distribution. Simulation study of the sample path of the arrival process is conducted. For this queueing system, the stationary distribution of the system size and the waiting time distribution of an arbitrary packet is obtained with the help of matrix analytic methods and Markov regenerative theory. The quantitative effect of the stationary distribution on system size, waiting time and  the autocorrelation function as well as the parameters of the input traffic is illustrated empirically. The model is applied to a real data on the passenger arrivals at a subway bus terminal in Santiago de Chile and is established that the model well suits this data.

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

    Science.gov (United States)

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

    2017-06-01

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

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

    KAUST Repository

    Hamza, Doha R.

    2011-03-01

    We study a multiple-access system with a primary user (PU) and a secondary user (SU) utilizing the same frequency band and communicating with a common receiver. Both users transmit with a fixed transmission rate by employing a channel inversion power control scheme. The SU transmits with a certain probability that depends on the sensing outcome, its queue length and whether it has a new packet arrival. We consider the case of erroneous sensing. The goal of the SU is to find the optimal transmission scheduling policy so as to minimize its queueing delay under constraints on its average transmit power and the maximum tolerable primary outage probability caused by miss-detection. The access probabilities are obtained efficiently using linear programming. © 2011 IEEE.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

    On the basis of variable structure control (VSC), an active queue management (AQM) controller is presented for a class of TCP communication networks. In the TCP/IP networks, the packet drop probability is limited between 0 and 1. Therefore, we modeled TCP/AQM as a rate-based non-linear system with a saturated input. The objective of the VSC-based AQM controller is to achieve the desired queue size and to guarantee the asymptotic stability of the closed-loop TCP non-linear system with saturated input. The performance and effectiveness of the proposed control law are then validated for different network scenarios through numerical simulations in both MATLAB and Network Simulator-2 (NS-2). Both sets of simulation results have confirmed that the proposed scheme outperforms other AQM schemes.

  7. A simple client-server system using a personal computer as the server.

    Science.gov (United States)

    Matsumura, K; Hanada, E; Antoku, Y; Kenjo, Y; Shiraishi, K; Kanmura, Y; Nose, Y

    2000-02-01

    Hospital information systems have recently grown into huge, complex systems. As a result, the cost of development and maintenance of application programs has increased and become a serious problem. We have constructed an order entry system using server-client architecture as part of a hospital intranet information system in which a personal computer is used as a server. Using a commercial database management system and software development tools, an easily maintained order entry system was developed within only three months by one programmer. Since slow response when the number of clients increased was possible, we measured turn-around times when one or ten clients accessed simultaneously. Turn-around times were 8 and 10 sec, respectively. Because we expect much better performance from personal computers in the near future, application systems using personal computers as Intranet servers will be cost and time effective and easy to develop and maintain.

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

    OpenAIRE

    Dhruba Das; Hemanta K. Baruah

    2015-01-01

    In this article, based on Zadeh’s extension principle we have apply the parametric programming approach to construct the membership functions of the performance measures when the interarrival time and the service time are fuzzy numbers based on the Baruah’s Randomness- Fuzziness Consistency Principle. The Randomness-Fuzziness Consistency Principle leads to defining a normal law of fuzziness using two different laws of randomness. In this article, two fuzzy queues FM...

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

    Science.gov (United States)

    Kim, Hyun Jong; Shim, Jae Chan; Kim, Hwa-Suk; Cho, Kee Seong; Choi, Seong Gon

    In this paper, we propose the active queue management mechanism (Active-WRED) for guaranteeing the quality of the high priority service class (VoIP or IPTV) in the multi-class traffic service environment. In the congestion situation, this mechanism increases the drop probability of the low priority traffic and reduces the drop probability of the high priority traffic; therefore it can guarantee the quality of the high priority service class from the poor quality by the packet loss.

  10. Modeling of temperatures by using the algorithm of queue burning movement in the UCG Process

    Directory of Open Access Journals (Sweden)

    Milan Durdán

    2015-10-01

    Full Text Available In this contribution, a proposal of the system for indirect measurement temperatures in the underground coal gasification (UCG process is presented. A two-dimensional solution results from the Fourier partial differential equation of the heat conduction was used for the calculation of the temperature field in the real coal seam. An algorithm of queue burning movement for modeling the boundary conditions in gasification channel was created. Indirect measurement temperatures system was verified in the laboratory conditions.

  11. Stochastic Analysis of a Queue Length Model Using a Graphics Processing Unit

    Czech Academy of Sciences Publication Activity Database

    Přikryl, Jan; Kocijan, J.

    2012-01-01

    Roč. 5, č. 2 (2012), s. 55-62 ISSN 1802-971X R&D Projects: GA MŠk(CZ) MEB091015 Institutional support: RVO:67985556 Keywords : graphics processing unit * GPU * Monte Carlo simulation * computer simulation * modeling Subject RIV: BC - Control Systems Theory http://library.utia.cas.cz/separaty/2012/AS/prikryl-stochastic analysis of a queue length model using a graphics processing unit.pdf

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

    Science.gov (United States)

    Bigdeli, N; Haeri, M

    2009-01-01

    Predictive functional control (PFC) as a new active queue management (AQM) method in dynamic TCP networks supporting explicit congestion notification (ECN) is proposed. The ability of the controller in handling system delay along with its simplicity and low computational load makes PFC a privileged AQM method in the high speed networks. Besides, considering the disturbance term (which represents model/process mismatches, external disturbances, and existing noise) in the control formulation adds some level of robustness into the PFC-AQM controller. This is an important and desired property in the control of dynamically-varying computer networks. In this paper, the controller is designed based on a small signal linearized fluid-flow model of the TCP/AQM networks. Then, closed-loop transfer function representation of the system is derived to analyze the robustness with respect to the network and controller parameters. The analytical as well as the packet-level ns-2 simulation results show the out-performance of the developed controller for both queue regulation and resource utilization. Fast response, low queue fluctuations (and consequently low delay jitter), high link utilization, good disturbance rejection, scalability, and low packet marking probability are other features of the developed method with respect to other well-known AQM methods such as RED, PI, and REM which are also simulated for comparison.

  13. A spatiotemporal model for the LTE uplink: Spatially interacting tandem queues approach

    KAUST Repository

    Gharbieh, Mohammad

    2017-07-31

    With the proliferation of the Internet-of-things (IoT), there is an undeniable consensus that cellular LTE networks will have to support a dramatically larger number of uplink connections. This is true since most of the devices to be added incur machine-type communications which is dominantly upstream. Can current LTE network withstand this challenge? To answer this question, the joint performance of random access process and the uplink data transmission should be investigated. These two problems have been classically treated in the literature in a disjoint fashion. In this paper, they are jointly analyzed as an inseparable couple. To do that, a tandem queuing model is adopted whereby devices are represented as spatially interacting queues. The interaction between queues is governed by the mutual inter-cell and intra-cell interference. To that end, a joint stochastic geometry and queueing theory model is exploited to study this problem and a spatiotemporal analytical model is developed accordingly. Network stability and scalability are two prime performance criteria for performance assessment. In light of these two criteria, the developed model is poised to offer valuable insights into efficient access and resource allocation strategies.

  14. Dynamic Performance Optimization for Cloud Computing Using M/M/m Queueing System

    Directory of Open Access Journals (Sweden)

    Lizheng Guo

    2014-01-01

    Full Text Available Successful development of cloud computing has attracted more and more people and enterprises to use it. On one hand, using cloud computing reduces the cost; on the other hand, using cloud computing improves the efficiency. As the users are largely concerned about the Quality of Services (QoS, performance optimization of the cloud computing has become critical to its successful application. In order to optimize the performance of multiple requesters and services in cloud computing, by means of queueing theory, we analyze and conduct the equation of each parameter of the services in the data center. Then, through analyzing the performance parameters of the queueing system, we propose the synthesis optimization mode, function, and strategy. Lastly, we set up the simulation based on the synthesis optimization mode; we also compare and analyze the simulation results to the classical optimization methods (short service time first and first in, first out method, which show that the proposed model can optimize the average wait time, average queue length, and the number of customer.

  15. Hospital Registration Process Reengineering Using Simulation Method

    Directory of Open Access Journals (Sweden)

    Qiang Su

    2010-01-01

    Full Text Available With increasing competition, many healthcare organizations have undergone tremendous reform in the last decade aiming to increase efficiency, decrease waste, and reshape the way that care is delivered. This study focuses on the operational efficiency improvement of hospital’s registration process. The operational efficiency related factors including the service process, queue strategy, and queue parameters were explored systematically and illustrated with a case study. Guided by the principle of business process reengineering (BPR, a simulation approach was employed for process redesign and performance optimization. As a result, the queue strategy is changed from multiple queues and multiple servers to single queue and multiple servers with a prepare queue. Furthermore, through a series of simulation experiments, the length of the prepare queue and the corresponding registration process efficiency was quantitatively evaluated and optimized.

  16. Web server for priority ordered multimedia services

    Science.gov (United States)

    Celenk, Mehmet; Godavari, Rakesh K.; Vetnes, Vermund

    2001-10-01

    In this work, our aim is to provide finer priority levels in the design of a general-purpose Web multimedia server with provisions of the CM services. The type of services provided include reading/writing a web page, downloading/uploading an audio/video stream, navigating the Web through browsing, and interactive video teleconferencing. The selected priority encoding levels for such operations follow the order of admin read/write, hot page CM and Web multicasting, CM read, Web read, CM write and Web write. Hot pages are the most requested CM streams (e.g., the newest movies, video clips, and HDTV channels) and Web pages (e.g., portal pages of the commercial Internet search engines). Maintaining a list of these hot Web pages and CM streams in a content addressable buffer enables a server to multicast hot streams with lower latency and higher system throughput. Cold Web pages and CM streams are treated as regular Web and CM requests. Interactive CM operations such as pause (P), resume (R), fast-forward (FF), and rewind (RW) have to be executed without allocation of extra resources. The proposed multimedia server model is a part of the distributed network with load balancing schedulers. The SM is connected to an integrated disk scheduler (IDS), which supervises an allocated disk manager. The IDS follows the same priority handling as the SM, and implements a SCAN disk-scheduling method for an improved disk access and a higher throughput. Different disks are used for the Web and CM services in order to meet the QoS requirements of CM services. The IDS ouput is forwarded to an Integrated Transmission Scheduler (ITS). The ITS creates a priority ordered buffering of the retrieved Web pages and CM data streams that are fed into an auto regressive moving average (ARMA) based traffic shaping circuitry before being transmitted through the network.

  17. Models of network access using feedback fluid queues

    NARCIS (Netherlands)

    Mandjes, M.R.H.; Mitra, D.; Scheinhardt, Willem R.W.

    2001-01-01

    At the access to networks, in contrast to the core, distances and feedback delays, as well as link capacities are small, which has network engineering implications that are investigated in this paper. We consider a single point in the access network which multiplexes several bursty users. The users

  18. Models of network access using feedback fluid queues

    NARCIS (Netherlands)

    Mandjes, M.R.H.; Mitra, Debasis; Scheinhardt, Willem R.W.

    At the access to networks, in contrast to the core, distances and feedback delays, as well as link capacities are small, which has network engineering implications that are investigated in this paper. We consider a single point in the access network which multiplexes several bursty users. The users

  19. Models of network access using feedback fluid queues

    NARCIS (Netherlands)

    M.R.H. Mandjes (Michel); D. Mitra; W.R.W. Scheinhardt (Werner)

    2002-01-01

    htmlabstractAt the access to networks, in contrast to the core, distances and feedback delay s, as well as link capacities are small, which has network engineering implications that are investigated in this paper. We consider a single point in the access network which multiplexes several bursty

  20. Integrating Live Access Server into Google Earth

    Science.gov (United States)

    Li, J.; Schweitzer, R.; Hankin, S.; O'Brien, K.

    2006-12-01

    The Live Access Server (LAS) is a highly configurable Web server designed to provide flexible access to visualization and analysis products generated from geo-referenced scientific data sets. Now at version 7.0, LAS has been in operation since 1994. The current ~{!0~}Armstrong?release of LAS V7 consists of a set of modular components in a three tiered architecture -- user interface, workflow orchestration and services to access data and generate scientific products. The LAS user interface (UI) helps the user make requests, preventing requests that are impossible or unreasonable. The UI communicates with the LAS Product Server (LPS the workflow orchestration component) via an XML string with an HTTP GET. When a request is received by the LPS, business logic converts this request into a series of Web Service requests invoked via SOAP. The SOAP services perform data access and generate products (visualizations, data subsets, analyses, etc.). LPS packages these outputs into final products via Jakarta Velocity templates for delivery to the end user. Back-end services are most often a legacy application wrapped in a Java class. The Java wrapper classes are deployed as Web Services accessible via SOAP using the AxisServlet and a custom Web Services Deployment Descriptor file. Ferret is the default visualization application used by LAS, though other applications (e.g. Matlab, CDAT, and GrADS) can also be used. This application demonstrates how Keyhole Markup Language (KML) can be used to provide simple integration of LAS and Google Earth. KML makes access to "Virtual Globe" capabilities so simple that it can be added as an option to existing systems. This application is one such example. The ability to package an image in KML was added to the LAS as a new SOAP service. On the LAS user interface, users can select a Google Earth product in the same manner that any other LAS product is requested. The server will dynamically generate a KML file, which contains the 2D plot

  1. Implementing VMware vCenter Server

    CERN Document Server

    Kuminsky, Konstantin

    2013-01-01

    This book is a practical, hands-on guide that will help you learn everything you need to know to administer your environment with VMware vCenter Server. Throughout the book, there are best practices and useful tips and tricks which can be used for day-to-day tasks.If you are an administrator or a technician starting with VMware, with little or no knowledge of virtualization products, this book is ideal for you. Even if you are an IT professional looking to expand your existing environment, you will be able to use this book to help you improve the management of these environments. IT managers w

  2. Instant MDX queries for SQL Server 2012

    CERN Document Server

    Emond, Nicholas

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. This short, focused guide is a great way to get stated with writing MDX queries. New developers can use this book as a reference for how to use functions and the syntax of a query as well as how to use Calculated Members and Named Sets.This book is great for new developers who want to learn the MDX query language from scratch and install SQL Server 2012 with Analysis Services

  3. Map server of Slovak Environmental Agency

    International Nuclear Information System (INIS)

    Koska, M.

    2005-01-01

    The Slovak Environmental Agency (SAZP) is professional organization of the Ministry of Environment of the Slovak Republic. In the area of informatics SAZP is responsible for operation of information system about environment in the Slovak Republic (ISE). The main goal of the ISE is collection, evaluating and accessing of relevant information about environment between organizations of state or administration, public administration, public, scientific institutes etc. SAZP uses technology of publishing of geo-space data so-called WEB maps (dynamic mapping) - maps are formed online. As a technologic part of information system is internet map server

  4. A client/server approach to telemedicine.

    Science.gov (United States)

    Vaughan, B J; Torok, K E; Kelly, L M; Ewing, D J; Andrews, L T

    1995-01-01

    This paper describes the Medical College of Ohio's efforts in developing a client/server telemedicine system. Telemedicine vastly improves the ability of a medical center physician or specialist to interactively consult with a physician at a remote health care facility. The patient receives attention more quickly, he and his family do not need to travel long distances to obtain specialists' services, and the primary care physician can be involved in diagnosis and developing a treatment program [1, 2]. Telemedicine consultations are designed to improve access to health services in underserved urban and rural communities and reduce isolation of rural practitioners [3].

  5. Client-server technology for merging practices.

    Science.gov (United States)

    Blonsley, G

    1998-01-01

    Mergers, acquisitions and multiple care sites have made day-to-day management of information a logistical nightmare for medical group managers. As medical groups consolidate, each care site, typically, joins the new organization using stand-alone billing, accounting and scheduling packages. These legacy systems offer no automated way to transfer information between care sites and a central office. Rather than replacing established operating systems, medical group managers can use rules-based, decision support software and host-based, or client/server, technology. This type of connectivity allows medical groups to collect, process and redistribute key information.

  6. Pro SQL Server 2008 Analysis Services

    CERN Document Server

    Janus, Philo B

    2009-01-01

    Every business has a reams of business data locked away in databases, business systems, and spreadsheets. While you may be able to build some reports by pulling a few of these repositories together, actually performing any kind of analysis on the data that runs your business can range from problematic to impossible. Pro SQL Server 2008 Analysis Services will show you how to pull that data together and present it for reporting and analysis in a way that makes the data accessible to business users, instead of needing to rely on the IT department every time someone needs a different report. * Acc

  7. Query Optimization Techniques in Microsoft SQL Server

    Directory of Open Access Journals (Sweden)

    Costel Gabriel CORLATAN

    2014-09-01

    Full Text Available Microsoft SQL Server is a relational database management system, having MS-SQL and Transact-SQL as primary structured programming languages. They rely on relational algebra which is mainly used for data insertion, modifying, deletion and retrieval, as well as for data access controlling. The problem with getting the expected results is handled by the management system which has the purpose of finding the best execution plan, this process being called optimization. The most frequently used queries are those of data retrieval through SELECT command. We have to take into consideration that not only the select queries need optimization, but also other objects, such as: index, view or statistics.

  8. Publication Life Cycle at CERN Document Server

    CERN Multimedia

    Witowski, Sebastian; Costa, Flavio; Gabancho, Esteban; Marian, Ludmila; Tzovanakis, Harris

    2017-01-01

    This presentation guides listeners through all the stages of publication life cycle at CERN Document Server, from the ingestion using one of the various tools, through curation and processing, until the data is ready to be exported to other systems. It describes different tools that we are using to curate the incoming publications as well as to further improve the existing data on CDS. The second part of the talk goes through various challenges we have faced in the past and how we are going to overcome them in the new version of CDS.

  9. Professional Microsoft SQL Server 2012 Reporting Services

    CERN Document Server

    Turley, Paul; Silva, Thiago; Withee, Ken; Paisley, Grant

    2012-01-01

    A must-have guide for the latest updates to the new release of Reporting Services SQL Server Reporting Services allows you to create reports and business intelligence (BI) solutions. With this updated resource, a team of experts shows you how Reporting Services makes reporting faster, easier and more powerful than ever in web, desktop, and portal solutions. New coverage discusses the new reporting tool called Crescent, BI semantic model's impact on report design and creation, semantic model design, and more. You'll explore the major enhancements to Report Builder and benefit from best practice

  10. BEBAN JARINGAN SAAT MENGAKSES EMAIL DARI BEBERAPA MAIL SERVER

    Directory of Open Access Journals (Sweden)

    Husni Thamrin

    2017-01-01

    Full Text Available Expensive internet facilities require prudent in its use both as a source of information and communication media. This paper discusses observations of the perceived burden of network bandwidth when accessing some of the mail server using a webmail application. Mail server in question consists of three commercial server and 2 non-commercial server. Data when it download home page, while logged in, open the email, and during idle logout recorded with sniffer Wireshark. Observations in various situations and scenarios indicate that access Yahoo email gives the network load is very high while the SquirrelMail gives the network load is very low than 5 other mail servers. For an institution, use a local mail server (institutional is highly recommended in the context of banddwidth savings.

  11. MARSIS data and simulation exploited using array databases: PlanetServer/EarthServer for sounding radars

    Science.gov (United States)

    Cantini, Federico; Pio Rossi, Angelo; Orosei, Roberto; Baumann, Peter; Misev, Dimitar; Oosthoek, Jelmer; Beccati, Alan; Campalani, Piero; Unnithan, Vikram

    2014-05-01

    MARSIS is an orbital synthetic aperture radar for both ionosphere and subsurface sounding on board ESA's Mars Express (Picardi et al. 2005). It transmits electromagnetic pulses centered at 1.8, 3, 4 or 5 MHz that penetrate below the surface and are reflected by compositional and/or structural discontinuities in the subsurface of Mars. MARSIS data are available as a collection of single orbit data files. The availability of tools for a more effective access to such data would greatly ease data analysis and exploitation by the community of users. For this purpose, we are developing a database built on the raster database management system RasDaMan (e.g. Baumann et al., 1994), to be populated with MARSIS data and integrated in the PlanetServer/EarthServer (e.g. Oosthoek et al., 2013; Rossi et al., this meeting) project. The data (and related metadata) are stored in the db for each frequency used by MARSIS radar. The capability of retrieving data belonging to a certain orbit or to multiple orbit on the base of latitute/longitude boundaries is a key requirement of the db design, allowing, besides the "classical" radargram representation of the data, and in area with sufficiently hight orbit density, a 3D data extraction, subset and analysis of subsurface structures. Moreover the use of the OGC WCPS (Web Coverage Processing Service) standard can allow calculations on database query results for multiple echoes and/or subsets of a certain data product. Because of the low directivity of its dipole antenna, MARSIS receives echoes from portions of the surface of Mars that are distant from nadir and can be mistakenly interpreted as subsurface echoes. For this reason, methods have been developed to simulate surface echoes (e.g. Nouvel et al., 2004), to reveal the true origin of an echo through comparison with instrument data. These simulations are usually time-consuming, and so far have been performed either on a case-by-case basis or in some simplified form. A code for

  12. CORAL Server and CORAL Server Proxy: Scalable Access to Relational Databases from CORAL Applications

    CERN Document Server

    Valassi, A; Kalkhof, A; Salnikov, A; Wache, M

    2011-01-01

    The CORAL software is widely used at CERN for accessing the data stored by the LHC experiments using relational database technologies. CORAL provides a C++ abstraction layer that supports data persistency for several backends and deployment models, including local access to SQLite files, direct client access to Oracle and MySQL servers, and read-only access to Oracle through the FroNTier web server and cache. Two new components have recently been added to CORAL to implement a model involving a middle tier "CORAL server" deployed close to the database and a tree of "CORAL server proxy" instances, with data caching and multiplexing functionalities, deployed close to the client. The new components are meant to provide advantages for read-only and read-write data access, in both offline and online use cases, in the areas of scalability and performance (multiplexing for several incoming connections, optional data caching) and security (authentication via proxy certificates). A first implementation of the two new c...

  13. TBI server: a web server for predicting ion effects in RNA folding.

    Directory of Open Access Journals (Sweden)

    Yuhong Zhu

    Full Text Available Metal ions play a critical role in the stabilization of RNA structures. Therefore, accurate prediction of the ion effects in RNA folding can have a far-reaching impact on our understanding of RNA structure and function. Multivalent ions, especially Mg²⁺, are essential for RNA tertiary structure formation. These ions can possibly become strongly correlated in the close vicinity of RNA surface. Most of the currently available software packages, which have widespread success in predicting ion effects in biomolecular systems, however, do not explicitly account for the ion correlation effect. Therefore, it is important to develop a software package/web server for the prediction of ion electrostatics in RNA folding by including ion correlation effects.The TBI web server http://rna.physics.missouri.edu/tbi_index.html provides predictions for the total electrostatic free energy, the different free energy components, and the mean number and the most probable distributions of the bound ions. A novel feature of the TBI server is its ability to account for ion correlation and ion distribution fluctuation effects.By accounting for the ion correlation and fluctuation effects, the TBI server is a unique online tool for computing ion-mediated electrostatic properties for given RNA structures. The results can provide important data for in-depth analysis for ion effects in RNA folding including the ion-dependence of folding stability, ion uptake in the folding process, and the interplay between the different energetic components.

  14. From Server to Desktop: Capital and Institutional Planning for Client/Server Technology.

    Science.gov (United States)

    Mullig, Richard M.; Frey, Keith W.

    1994-01-01

    Beginning with a request for an enhanced system for decision/strategic planning support, the University of Chicago's biological sciences division has developed a range of administrative client/server tools, instituted a capital replacement plan for desktop technology, and created a planning and staffing approach enabling rapid introduction of new…

  15. TBI server: a web server for predicting ion effects in RNA folding.

    Science.gov (United States)

    Zhu, Yuhong; He, Zhaojian; Chen, Shi-Jie

    2015-01-01

    Metal ions play a critical role in the stabilization of RNA structures. Therefore, accurate prediction of the ion effects in RNA folding can have a far-reaching impact on our understanding of RNA structure and function. Multivalent ions, especially Mg²⁺, are essential for RNA tertiary structure formation. These ions can possibly become strongly correlated in the close vicinity of RNA surface. Most of the currently available software packages, which have widespread success in predicting ion effects in biomolecular systems, however, do not explicitly account for the ion correlation effect. Therefore, it is important to develop a software package/web server for the prediction of ion electrostatics in RNA folding by including ion correlation effects. The TBI web server http://rna.physics.missouri.edu/tbi_index.html provides predictions for the total electrostatic free energy, the different free energy components, and the mean number and the most probable distributions of the bound ions. A novel feature of the TBI server is its ability to account for ion correlation and ion distribution fluctuation effects. By accounting for the ion correlation and fluctuation effects, the TBI server is a unique online tool for computing ion-mediated electrostatic properties for given RNA structures. The results can provide important data for in-depth analysis for ion effects in RNA folding including the ion-dependence of folding stability, ion uptake in the folding process, and the interplay between the different energetic components.

  16. Average Delay Guarantee in Server Systems Using Admission Control

    OpenAIRE

    Malrait, Luc; Marchand, Nicolas; Bouchenak, Sara

    2009-01-01

    International audience; Although server technology provides a mean to support a wide range of online services and applications, their ad-hoc conguration poses signicant challenges to the perfor- mance, availability and economical costs of applications. One of the main concerns is that under a heavy load, the delay introduced by a server in the transaction process may grow unbounded. This paper precisely addresses this issue. First, we present the design of a server model as a non-linear conti...

  17. Implementasi Load Balancing Web Server Menggunakan Metode LVS-NAT

    OpenAIRE

    Rabu, Jefry Alvonsius; Purwadi, Joko; Raharjo, Willy Sudiarto

    2012-01-01

    Web server plays a vital role on serving requests from clients. As Internet users grows so fast, the request number increases significantly, thus reducing the overall performance of the web server. One solution is to implement a load balancing system.In this paper, we implement load balancing with Linux Virtual Server to distribute the load to several machines within a cluster. We compared Round Robbin and Least Connection algorithm. The study reveals that load balancing using LVS-NAT can dou...

  18. Remote Sensing Data Analytics for Planetary Science with PlanetServer/EarthServer

    Science.gov (United States)

    Rossi, Angelo Pio; Figuera, Ramiro Marco; Flahaut, Jessica; Martinot, Melissa; Misev, Dimitar; Baumann, Peter; Pham Huu, Bang; Besse, Sebastien

    2016-04-01

    Planetary Science datasets, beyond the change in the last two decades from physical volumes to internet-accessible archives, still face the problem of large-scale processing and analytics (e.g. Rossi et al., 2014, Gaddis and Hare, 2015). PlanetServer, the Planetary Science Data Service of the EC-funded EarthServer-2 project (#654367) tackles the planetary Big Data analytics problem with an array database approach (Baumann et al., 2014). It is developed to serve a large amount of calibrated, map-projected planetary data online, mainly through Open Geospatial Consortium (OGC) Web Coverage Processing Service (WCPS) (e.g. Rossi et al., 2014; Oosthoek et al., 2013; Cantini et al., 2014). The focus of the H2020 evolution of PlanetServer is still on complex multidimensional data, particularly hyperspectral imaging and topographic cubes and imagery. In addition to hyperspectral and topographic from Mars (Rossi et al., 2014), the use of WCPS is applied to diverse datasets on the Moon, as well as Mercury. Other Solar System Bodies are going to be progressively available. Derived parameters such as summary products and indices can be produced through WCPS queries, as well as derived imagery colour combination products, dynamically generated and accessed also through OGC Web Coverage Service (WCS). Scientific questions translated into queries can be posed to a large number of individual coverages (data products), locally, regionally or globally. The new PlanetServer system uses the the Open Source Nasa WorldWind (e.g. Hogan, 2011) virtual globe as visualisation engine, and the array database Rasdaman Community Edition as core server component. Analytical tools and client components of relevance for multiple communities and disciplines are shared across service such as the Earth Observation and Marine Data Services of EarthServer. The Planetary Science Data Service of EarthServer is accessible on http://planetserver.eu. All its code base is going to be available on GitHub, on

  19. Web-Beagle: a web server for the alignment of RNA secondary structures.

    Science.gov (United States)

    Mattei, Eugenio; Pietrosanto, Marco; Ferrè, Fabrizio; Helmer-Citterich, Manuela

    2015-07-01

    Web-Beagle (http://beagle.bio.uniroma2.it) is a web server for the pairwise global or local alignment of RNA secondary structures. The server exploits a new encoding for RNA secondary structure and a substitution matrix of RNA structural elements to perform RNA structural alignments. The web server allows the user to compute up to 10 000 alignments in a single run, taking as input sets of RNA sequences and structures or primary sequences alone. In the latter case, the server computes the secondary structure prediction for the RNAs on-the-fly using RNAfold (free energy minimization). The user can also compare a set of input RNAs to one of five pre-compiled RNA datasets including lncRNAs and 3' UTRs. All types of comparison produce in output the pairwise alignments along with structural similarity and statistical significance measures for each resulting alignment. A graphical color-coded representation of the alignments allows the user to easily identify structural similarities between RNAs. Web-Beagle can be used for finding structurally related regions in two or more RNAs, for the identification of homologous regions or for functional annotation. Benchmark tests show that Web-Beagle has lower computational complexity, running time and better performances than other available methods. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  20. Foundations of SQL Server 2008 R2 Business Intelligence

    CERN Document Server

    Fouche, Guy

    2011-01-01

    Foundations of SQL Server 2008 R2 Business Intelligence introduces the entire exciting gamut of business intelligence tools included with SQL Server 2008. Microsoft has designed SQL Server 2008 to be more than just a database. It's a complete business intelligence (BI) platform. The database is at its core, and surrounding the core are tools for data mining, modeling, reporting, analyzing, charting, and integration with other enterprise-level software packages. SQL Server 2008 puts an incredible amount of BI functionality at your disposal. But how do you take advantage of it? That's what this