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...
Chen, Junting; Lau, Vincent K. N.
2013-01-01
Max weighted queue (MWQ) control policy is a widely used cross-layer control policy that achieves queue stability and a reasonable delay performance. In most of the existing literature, it is assumed that optimal MWQ policy can be obtained instantaneously at every time slot. However, this assumption may be unrealistic in time varying wireless systems, especially when there is no closed-form MWQ solution and iterative algorithms have to be applied to obtain the optimal solution. This paper investigates the convergence behavior and the queue delay performance of the conventional MWQ iterations in which the channel state information (CSI) and queue state information (QSI) are changing in a similar timescale as the algorithm iterations. Our results are established by studying the stochastic stability of an equivalent virtual stochastic dynamic system (VSDS), and an extended Foster-Lyapunov criteria is applied for the stability analysis. We derive a closed form delay bound of the wireless network in terms of the CSI fading rate and the sensitivity of MWQ policy over CSI and QSI. Based on the equivalent VSDS, we propose a novel MWQ iterative algorithm with compensation to improve the tracking performance. We demonstrate that under some mild conditions, the proposed modified MWQ algorithm converges to the optimal MWQ control despite the time-varying CSI and QSI.
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...
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...
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....
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 ...
The Remaining Service Time Upon Reaching a High Level in M/G/1 Queues
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,
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...
Large deviations for sojourn times in processor sharing queues.
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.
First in line waiting times as a tool for analyzing queueing systems
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
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...
Predicting clinical image delivery time by monitoring PACS queue behavior.
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.
Gombolay, Matthew; Golen, Toni; Shah, Neel; Shah, Julie
2017-09-04
Childbirth is a complex clinical service requiring the coordinated support of highly trained healthcare professionals as well as management of a finite set of critical resources (such as staff and beds) to provide safe care. The mode of delivery (vaginal delivery or cesarean section) has a significant effect on labor and delivery resource needs. Further, resource management decisions may impact the amount of time a physician or nurse is able to spend with any given patient. In this work, we employ queueing theory to model one year of transactional patient information at a tertiary care center in Boston, Massachusetts. First, we observe that the M/G/∞ model effectively predicts patient flow in an obstetrics department. This model captures the dynamics of labor and delivery where patients arrive randomly during the day, the duration of their stay is based on their individual acuity, and their labor progresses at some rate irrespective of whether they are given a bed. Second, using our queueing theoretic model, we show that reducing the rate of cesarean section - a current quality improvement goal in American obstetrics - may have important consequences with regard to the resource needs of a hospital. We also estimate the potential financial impact of these resource needs from the hospital perspective. Third, we report that application of our model to an analysis of potential patient coverage strategies supports the adoption of team-based care, in which attending physicians share responsibilities for patients.
A queueing-theoretic analysis of the threshold-based exhaustive data-backup scheduling policy
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.
Care on demand in nursing homes: a queueing theoretic approach.
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.
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...
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.
Single-Server Queueing System with Markov-Modulated Arrivals and Service Times
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...
Time Is Not on Our Side: How Radiology Practices Should Manage Customer Queues.
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.
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...
Real-time prediction of queues at signalized intersections to support eco-driving applications.
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 ...
NPS and the methadone queue: Spillages of space and time.
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.
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.
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.
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.
A two-station queue with dependent preparation and service times
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
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....
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.
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.
Sojourn time asymptotics in Processor Sharing queues with varying service rate
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
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.
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.
International Nuclear Information System (INIS)
Shah, S.A.; Shah, W.; Shaikh, F.K.
2012-01-01
Flow time analysis is a powerful concept to analyze the flow time of any arriving customer in any system at any instant. A load management mechanism can be employed very effectively in any queueing system by utilizing a system which provides probability of dual service rate. In this paper, we develop and demonstrate the flow and service processes transition diagram to determine the flow time of a customer in a load management late arrival state dependent finite discrete time queueing system with dual service rate where customers are hypo geometrically distributed. We compute the probability mass function of each starting state and total probability mass function. The obtained analytical results are validated with simulation results for varying values of arrival and service probabilities. (author)
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....
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.
Directory of Open Access Journals (Sweden)
Vedat Sağlam
2015-01-01
Full Text Available The aim of this paper is to analyze a tandem queueing model with two stages. The arrivals to the first stage are Poisson stream and the service time at this stage is exponential. There is no waiting room at first stage. The service time is hyperexponential and no waiting is allowed at second stage. The transition probabilities and loss probabilities of this model are obtained. In addition, the loss probability at second stage is optimized. Performance measures and the variance of the numbers of customers of this tandem queueing model are found. It is seen that the numbers of customers in first stage and second stage are dependent. Finally we have simulated this queueing model. For different values of parameters, exact values, simulated values, and optimal values of obtained performance measures of this model are numerically shown in tables and graphs.
A heavy-traffic theorem for the GI/G/1 queue with a Pareto-type service time distribution
J.W. Cohen
1997-01-01
textabstractFor the $GI/G/1$-queueing model with traffic load $a<1$, service time distribution $B(t)$ and interarrival time distribution $A(t)$ holds, whenever for $t rightarrow infty$: $$ quad 1-B(t) sim frac{c{(t/ beta)^nu + {rm O ( {rm e^{-delta t ), quad c>0, quad 1< nu < 2, quad delta >
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...
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...
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...
Meng, Tianhui; Li, Xiaofan; Zhang, Sha; Zhao, Yubin
2016-09-28
Wireless sensor networks (WSNs) have recently gained popularity for a wide spectrum of applications. Monitoring tasks can be performed in various environments. This may be beneficial in many scenarios, but it certainly exhibits new challenges in terms of security due to increased data transmission over the wireless channel with potentially unknown threats. Among possible security issues are timing attacks, which are not prevented by traditional cryptographic security. Moreover, the limited energy and memory resources prohibit the use of complex security mechanisms in such systems. Therefore, balancing between security and the associated energy consumption becomes a crucial challenge. This paper proposes a secure scheme for WSNs while maintaining the requirement of the security-performance tradeoff. In order to proceed to a quantitative treatment of this problem, a hybrid continuous-time Markov chain (CTMC) and queueing model are put forward, and the tradeoff analysis of the security and performance attributes is carried out. By extending and transforming this model, the mean time to security attributes failure is evaluated. Through tradeoff analysis, we show that our scheme can enhance the security of WSNs, and the optimal rekeying rate of the performance and security tradeoff can be obtained.
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.
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.
Analysis of queues methods and applications
Gautam, Natarajan
2012-01-01
Introduction Analysis of Queues: Where, What, and How?Systems Analysis: Key ResultsQueueing Fundamentals and Notations Psychology in Queueing Reference Notes Exercises Exponential Interarrival and Service Times: Closed-Form Expressions Solving Balance Equations via Arc CutsSolving Balance Equations Using Generating Functions Solving Balance Equations Using Reversibility Reference Notes ExercisesExponential Interarrival and Service Times: Numerical Techniques and Approximations Multidimensional Birth and Death ChainsMultidimensional Markov Chains Finite-State Markov ChainsReference Notes Exerci
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....
Queues with Choice via Delay Differential Equations
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.
Monotonicity in the limited processor sharing queue
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
A tandem queue with delayed server release
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
A geometric process model for M/PH(M/PH)/1/K queue with new service machine procurement lead time
Yu, Miaomiao; Tang, Yinghui; Fu, Yonghong
2013-06-01
In this article, we consider a geometric process model for M/PH(M/PH)/1/K queue with new service machine procurement lead time. A maintenance policy (N - 1, N) based on the number of failures of the service machine is introduced into the system. Assuming that a failed service machine after repair will not be 'as good as new', and the spare service machine for replacement is only available by an order. More specifically, we suppose that the procurement lead time for delivering the spare service machine follows a phase-type (PH) distribution. Under such assumptions, we apply the matrix-analytic method to develop the steady state probabilities of the system, and then we obtain some system performance measures. Finally, employing an important Lemma, the explicit expression of the long-run average cost rate for the service machine is derived, and the direct search method is also implemented to determine the optimal value of N for minimising the average cost rate.
Queueing networks a fundamental approach
Dijk, Nico
2011-01-01
This handbook aims to highlight fundamental, methodological and computational aspects of networks of queues to provide insights and to unify results that can be applied in a more general manner. The handbook is organized into five parts: Part 1 considers exact analytical results such as of product form type. Topics include characterization of product forms by physical balance concepts and simple traffic flow equations, classes of service and queue disciplines that allow a product form, a unified description of product forms for discrete time queueing networks, insights for insensitivity, and aggregation and decomposition results that allow subnetworks to be aggregated into single nodes to reduce computational burden. Part 2 looks at monotonicity and comparison results such as for computational simplification by either of two approaches: stochastic monotonicity and ordering results based on the ordering of the proces generators, and comparison results and explicit error bounds based on an underlying Markov r...
Jaiswal, N.K
1968-01-01
In this book, we study theoretical and practical aspects of computing methods for mathematical modelling of nonlinear systems. A number of computing techniques are considered, such as methods of operator approximation with any given accuracy; operator interpolation techniques including a non-Lagrange interpolation; methods of system representation subject to constraints associated with concepts of causality, memory and stationarity; methods of system representation with an accuracy that is the best within a given class of models; methods of covariance matrix estimation;methods for low-rank mat
Markov-modulated M/G/1-type queue in heavy traffic and its application to time-sharing disciplines
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
Queueing systems with constant service time and evaluation of M/D/1,k
DEFF Research Database (Denmark)
Iversen, Villy Bæk
1997-01-01
Systems with constant service times have the particular property that the customers leave the servers in the same order in which they areaccepted for service. Probabilitites of integral waiting times can be expressed by the state probabilities, and non-integral waiting timescan be expressed by in...... by integral waiting times. This in combination by a result by Keilson results in an effective algorithm for evaluating M/D/1,k....
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.
Real-Time Wait-Free Queues using Micro-Transactions
DEFF Research Database (Denmark)
Meawad, Fadi; Iyer, Karthik; Schoeberl, Martin
2011-01-01
This paper evaluates the applicability of transactional mem- ory to the implementation of dierent non-blocking data structures in the context of the Real-time Specication for Java. In particular, we argue that hardware support for micro-transaction allows us to implement eciently data structures...
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
Fundamentals of queueing theory
Gross, Donald; Thompson, James M; Harris, Carl M
2013-01-01
Praise for the Third Edition ""This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented.""-IIE Transactions on Operations Engineering Thoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than pre
Near optimal admission control for multiserver loss queues in series
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...
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.
Interacting queues in heavy traffic
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
The symmetric longest queue system
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
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....
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.
Analysis of the asymmetrical shortest two-server queueing model
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
Note on a tandem queue with delayed server release
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
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.
A tandem queue with delayed server release
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...
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.
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
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.
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....
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
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...
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.
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 ...
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
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...
Electromagnetic nuclear life time - theoretical context
International Nuclear Information System (INIS)
Niez, J.J.
2000-01-01
One describes here the theoretical tools which are needed for evaluating the nuclear lifetime of a nucleus dipped into electromagnetic surroundings which are composed of electrons and photons. The case where this environment is a material or a cavity will be treated in a following report. (Author)
Numbers or apologies? Customer reactions to telephone waiting time fillers.
Munichor, Nira; Rafaeli, Anat
2007-03-01
The authors examined the effect of time perception and sense of progress in telephone queues on caller reactions to 3 telephone waiting time fillers: music, apologies, and information about location in the queue. In Study 1, conducted on 123 real calls, call abandonment was lowest, and call evaluations were most positive with information about location in the queue as the time filler. In Study 2, conducted with 83 participants who experienced a simulated telephone wait experience, sense of progress in the queue rather than perceived waiting time mediated the relationship between telephone waiting time filler and caller reactions. The findings provide insight for the management and design of telephone queues, as well as theoretical insight into critical cognitive processes that underlie telephone waiting, opening up an important new research agenda. (c) 2007 APA, all rights reserved.
DEFF Research Database (Denmark)
Kozlowski, Dawid; Worthington, Dave
2015-01-01
Many public healthcare systems struggle with excessive waiting lists for elective patient treatment. Different countries address this problem in different ways, and one interesting method entails a maximum waiting time guarantee. Introduced in Denmark in 2002, it entitles patients to treatment...... chain and discrete event simulation models, to provide an insightful analysis of the public hospital performance under the policy rules. The aim of this paper is to support the enhancement of the quality of elective patient care, to be brought about by better understanding of the policy implications...
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
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
A single server queue with batch arrivals and semi-Markov services
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 M^{X}/G/1 queue with semi-Markov service times is the most prominent example in this class and serves as a vehicle to display
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
Probability, statistics, and queueing theory
Allen, Arnold O
1990-01-01
This is a textbook on applied probability and statistics with computer science applications for students at the upper undergraduate level. It may also be used as a self study book for the practicing computer science professional. The successful first edition of this book proved extremely useful to students who need to use probability, statistics and queueing theory to solve problems in other fields, such as engineering, physics, operations research, and management science. The book has also been successfully used for courses in queueing theory for operations research students. This second edit
A Central Limit Theorem for Markov-Modulated Infinite-Server Queues
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
Central Limit Theorems for Markov-modulated infinite-server queues
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
Queueing system analysis of multi server model at XYZ insurance company in Tasikmalaya city
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.
Slowdown in the $M/M/1$ discriminatory processor-sharing queue
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
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.
Vacation queueing models theory and applications
Tian, Naishuo
2006-01-01
A classical queueing model consists of three parts - arrival process, service process, and queue discipline. However, a vacation queueing model has an additional part - the vacation process which is governed by a vacation policy - that can be characterized by three aspects: 1) vacation start-up rule; 2) vacation termination rule, and 3) vacation duration distribution. Hence, vacation queueing models are an extension of classical queueing theory. Vacation Queueing Models: Theory and Applications discusses systematically and in detail the many variations of vacation policy. By allowing servers to take vacations makes the queueing models more realistic and flexible in studying real-world waiting line systems. Integrated in the book's discussion are a variety of typical vacation model applications that include call centers with multi-task employees, customized manufacturing, telecommunication networks, maintenance activities, etc. Finally, contents are presented in a "theorem and proof" format and it is invaluabl...
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.
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 ...
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.
Efficient estimation of overflow probabilities in queues with breakdowns
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
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 ...
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 ...
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.
GPS queues with heterogeneous traffic classes
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
Gaussian queues in light and heavy traffic
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,
The WIYN Queue: Theory Meets Reality
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.
Tandem queue with server slow-down
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
Conservative parallel simulation of priority class queueing networks
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.
Study on the Calculation Models of Bus Delay at Bays Using Queueing Theory and Markov Chain
Directory of Open Access Journals (Sweden)
Feng Sun
2015-01-01
Full Text Available Traffic congestion at bus bays has decreased the service efficiency of public transit seriously in China, so it is crucial to systematically study its theory and methods. However, the existing studies lack theoretical model on computing efficiency. Therefore, the calculation models of bus delay at bays are studied. Firstly, the process that buses are delayed at bays is analyzed, and it was found that the delay can be divided into entering delay and exiting delay. Secondly, the queueing models of bus bays are formed, and the equilibrium distribution functions are proposed by applying the embedded Markov chain to the traditional model of queuing theory in the steady state; then the calculation models of entering delay are derived at bays. Thirdly, the exiting delay is studied by using the queueing theory and the gap acceptance theory. Finally, the proposed models are validated using field-measured data, and then the influencing factors are discussed. With these models the delay is easily assessed knowing the characteristics of the dwell time distribution and traffic volume at the curb lane in different locations and different periods. It can provide basis for the efficiency evaluation of bus bays.
On a generic class of two-node queueing systems
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
MQCC: Maximum Queue Congestion Control for Multipath Networks with Blockage
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
Theoretical information measurement in nonrelativistic time-dependent approach
Najafizade, S. A.; Hassanabadi, H.; Zarrinkamar, S.
2018-02-01
The information-theoretic measures of time-dependent Schrödinger equation are investigated via the Shannon information entropy, variance and local Fisher quantities. In our calculations, we consider the two first states n = 0,1 and obtain the position Sx (t) and momentum Sp (t) Shannon entropies as well as Fisher information Ix (t) in position and momentum Ip (t) spaces. Using the Fourier transformed wave function, we obtain the results in momentum space. Some interesting features of the information entropy densities ρs (x,t) and γs (p,t), as well as the probability densities ρ (x,t) and γ (p,t) for time-dependent states are demonstrated. We establish a general relation between variance and Fisher's information. The Bialynicki-Birula-Mycielski inequality is tested and verified for the states n = 0,1.
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.
Notes on economic time series analysis system theoretic perspectives
Aoki, Masanao
1983-01-01
In seminars and graduate level courses I have had several opportunities to discuss modeling and analysis of time series with economists and economic graduate students during the past several years. These experiences made me aware of a gap between what economic graduate students are taught about vector-valued time series and what is available in recent system literature. Wishing to fill or narrow the gap that I suspect is more widely spread than my personal experiences indicate, I have written these notes to augment and reor ganize materials I have given in these courses and seminars. I have endeavored to present, in as much a self-contained way as practicable, a body of results and techniques in system theory that I judge to be relevant and useful to economists interested in using time series in their research. I have essentially acted as an intermediary and interpreter of system theoretic results and perspectives in time series by filtering out non-essential details, and presenting coherent accounts of wha...
Queues and Lévy fluctuation theory
Dębicki, Krzysztof
2015-01-01
The book provides an extensive introduction to queueing models driven by Lévy-processes as well as a systematic account of the literature on Lévy-driven queues. The objective is to make the reader familiar with the wide set of probabilistic techniques that have been developed over the past decades, including transform-based techniques, martingales, rate-conservation arguments, change-of-measure, importance sampling, and large deviations. On the application side, it demonstrates how Lévy traffic models arise when modelling current queueing-type systems (as communication networks) and includes applications to finance. Queues and Lévy Fluctuation Theory will appeal to graduate/postgraduate students and researchers in mathematics, computer science, and electrical engineering. Basic prerequisites are probability theory and stochastic processes.
Exclusive queueing model including the choice of service windows
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.
Bachmat, Eitan
2014-01-01
This monograph describes problems in the field of performance analysis, primarily the study of storage systems and the diverse mathematical techniques that are required for solving such problems. Topics covered include best practices for scheduling I/O requests to a disk drive, how this problem is related to airplane boarding, and how both problems can be modeled using space-time geometry. The author also explains how Riemann's proof of the analytic continuation and functional equation of the Riemann zeta function can be used to analyze express-line queues in a minimarket. Overall, the book reveals the surprising applicability of abstract mathematical ideas that are not usually associated with applied topics. Advanced undergraduate students or graduate students with an interest in the applications of mathematics will find this book a useful resource. It will also be of interest to professional mathematicians who want exposure to the surprising ways that theoretical mathematics may be applied to engineering pr...
A Closed Network Queue Model of Underground Coal Mining Production, Failure, and Repair
Lohman, G. M.
1978-01-01
Underground coal mining system production, failures, and repair cycles were mathematically modeled as a closed network of two queues in series. The model was designed to better understand the technological constraints on availability of current underground mining systems, and to develop guidelines for estimating the availability of advanced mining systems and their associated needs for spares as well as production and maintenance personnel. It was found that: mine performance is theoretically limited by the maintainability ratio, significant gains in availability appear possible by means of small improvements in the time between failures the number of crews and sections should be properly balanced for any given maintainability ratio, and main haulage systems closest to the mine mouth require the most attention to reliability.
Pricing Analysis in Geo/Geo/1 Queueing System
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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.
Preventing messaging queue deadlocks in a DMA environment
Blocksome, Michael A; Chen, Dong; Gooding, Thomas; Heidelberger, Philip; Parker, Jeff
2014-01-14
Embodiments of the invention may be used to manage message queues in a parallel computing environment to prevent message queue deadlock. A direct memory access controller of a compute node may determine when a messaging queue is full. In response, the DMA may generate and interrupt. An interrupt handler may stop the DMA and swap all descriptors from the full messaging queue into a larger queue (or enlarge the original queue). The interrupt handler then restarts the DMA. Alternatively, the interrupt handler stops the DMA, allocates a memory block to hold queue data, and then moves descriptors from the full messaging queue into the allocated memory block. The interrupt handler then restarts the DMA. During a normal messaging advance cycle, a messaging manager attempts to inject the descriptors in the memory block into other messaging queues until the descriptors have all been processed.
Queueing network model for obstetric patient flow in a hospital.
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.
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
The WorkQueue project - a task queue for the CMS workload management system
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
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
Diagonal queue medical image steganography with Rabin cryptosystem.
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.
Queueing models for token and slotted ring networks. Thesis
Peden, Jeffery H.
1990-01-01
Currently the end-to-end delay characteristics of very high speed local area networks are not well understood. The transmission speed of computer networks is increasing, and local area networks especially are finding increasing use in real time systems. Ring networks operation is generally well understood for both token rings and slotted rings. There is, however, a severe lack of queueing models for high layer operation. There are several factors which contribute to the processing delay of a packet, as opposed to the transmission delay, e.g., packet priority, its length, the user load, the processor load, the use of priority preemption, the use of preemption at packet reception, the number of processors, the number of protocol processing layers, the speed of each processor, and queue length limitations. Currently existing medium access queueing models are extended by adding modeling techniques which will handle exhaustive limited service both with and without priority traffic, and modeling capabilities are extended into the upper layers of the OSI model. Some of the model are parameterized solution methods, since it is shown that certain models do not exist as parameterized solutions, but rather as solution methods.
Computing moving and intermittent queue propagation in highway work zones.
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...
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.
Stochastic network optimization with application to communication and queueing systems
Neely, Michael
2010-01-01
This text presents a modern theory of analysis, control, and optimization for dynamic networks. Mathematical techniques of Lyapunov drift and Lyapunov optimization are developed and shown to enable constrained optimization of time averages in general stochastic systems. The focus is on communication and queueing systems, including wireless networks with time-varying channels, mobility, and randomly arriving traffic. A simple drift-plus-penalty framework is used to optimize time averages such as throughput, throughput-utility, power, and distortion. Explicit performance-delay tradeoffs are prov
Some reflections on the Renewal-theory paradox in queueing theory
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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.
Difference and differential equations with applications in queueing theory
Haghighi, Aliakbar Montazer
2013-01-01
A Useful Guide to the Interrelated Areas of Differential Equations, Difference Equations, and Queueing Models Difference and Differential Equations with Applications in Queueing Theory presents the unique connections between the methods and applications of differential equations, difference equations, and Markovian queues. Featuring a comprehensive collection of
Cost sharing of cooperating queues in a Jackson network
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
State-dependent importance sampling for a slowdown tandem queue
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
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.
Method and apparatus for efficiently tracking queue entries relative to a timestamp
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.
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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.
Open problems in Gaussian fluid queueing theory
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
Unreliable Retrial Queues in a Random Environment
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
Dobrushin's approach to queueing network theory
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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.
Joint distributions for interacting fluid queues
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
Markov-modulated and feedback fluid queues
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
Labour costs and queueing theory in retailing
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
Adaptive Importance Sampling Simulation of Queueing Networks
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
Decomposition and aggregation in queueing networks
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
Adaptive Filtering Queueing for Improving Fairness
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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.
A queueing model for error control of partial buffer sharing in ATM
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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.
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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.
Reachability in continuous-time Markov reward decision processes
Baier, Christel; Haverkort, Boudewijn R.H.M.; Hermanns, H.; Katoen, Joost P.; Flum, J.; Graedel, E.; Wilke, Th.
Continuous-time Markov decision processes (CTMDPs) are widely used for the control of queueing systems, epidemic and manufacturing processes. Various results on optimal schedulers for discounted and average reward optimality criteria in CTMDPs are known, but the typical game-theoretic winning
Analysis of Fuzzy Queue Characteristics by Flexible Alpha-cuts Method
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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.
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.
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.
Simple and efficient importance sampling scheme for a tandem queue with server slow-down
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
THEORETICAL REVIEW The Hippocampus, Time, and Memory Across Scales
Howard, Marc W.; Eichenbaum, Howard
2014-01-01
A wealth of experimental studies with animals have offered insights about how neural networks within the hippocampus support the temporal organization of memories. These studies have revealed the existence of “time cells” that encode moments in time, much as the well-known “place cells” map locations in space. Another line of work inspired by human behavioral studies suggests that episodic memories are mediated by a state of temporal context that changes gradually over long time scales, up to at least a few thousand seconds. In this view, the “mental time travel” hypothesized to support the experience of episodic memory corresponds to a “jump back in time” in which a previous state of temporal context is recovered. We suggest that these 2 sets of findings could be different facets of a representation of temporal history that maintains a record at the last few thousand seconds of experience. The ability to represent long time scales comes at the cost of discarding precise information about when a stimulus was experienced—this uncertainty becomes greater for events further in the past. We review recent computational work that describes a mechanism that could construct such a scale-invariant representation. Taken as a whole, this suggests the hippocampus plays its role in multiple aspects of cognition by representing events embedded in a general spatiotemporal context. The representation of internal time can be useful across nonhippocampal memory systems. PMID:23915126
Interevent time distribution in seismicity: A theoretical approach
International Nuclear Information System (INIS)
Molchan, G.
2004-09-01
This paper presents an analysis of the distribution of the time τ between two consecutive events in a stationary point process. The study is motivated by the discovery of unified scaling laws for τ for the case of seismic events. We demonstrate that these laws cannot exist simultaneously in a seismogenic area. Under very natural assumptions we show that if, after resealing to ensure Eτ = 1, the interevent time has a universal distribution F, then F must be exponential. In other words, Corral's unified scaling law cannot exist in the whole range of time. In the framework of a general cluster model we discuss the parameterization of an empirical unified law and the physical meaning of the parameters involved
Handbook of Time Series Analysis Recent Theoretical Developments and Applications
Schelter, Björn; Timmer, Jens
2006-01-01
This handbook provides an up-to-date survey of current research topics and applications of time series analysis methods written by leading experts in their fields. It covers recent developments in univariate as well as bivariate and multivariate time series analysis techniques ranging from physics' to life sciences' applications. Each chapter comprises both methodological aspects and applications to real world complex systems, such as the human brain or Earth's climate. Covering an exceptionally broad spectrum of topics, beginners, experts and practitioners who seek to understand the latest de
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.
Large deviations for tandem queueing systems
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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.
Care on demand in nursing homes: a queueing theoretic approach
Van Eeden, K.; Moeke, D.; Bekker, R.
2014-01-01
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
On the Control of a Queueing System with Aging State Information
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
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
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 ...
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.
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.
Space and Time as Relations: The Theoretical Approach of Leibniz
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Basil Evangelidis
2018-04-01
Full Text Available The epistemological rupture of Copernicus, the laws of planetary motions of Kepler, the comprehensive physical observations of Galileo and Huygens, the conception of relativity, and the physical theory of Newton were components of an extremely fertile and influential cognitive environment that prompted the restless Leibniz to shape an innovative theory of space and time. This theory expressed some of the concerns and intuitions of the scientific community of the seventeenth century, in particular the scientific group of the Academy of Sciences of Paris, but remained relatively unknown until the twentieth century. After Einstein, however, the relational theory of Leibniz gained wider respect and fame. The aim of this article is to explain how Leibniz foresaw relativity, through his critique of contemporary mechanistic philosophy.
Proposal for optimal placement platform of bikes using queueing networks.
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.
Fokker-Planck description for the queue dynamics of large tick stocks
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.
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.
Korelin, Ivan A.; Porshnev, Sergey V.
2018-01-01
The paper demonstrates the possibility of calculating the characteristics of the flow of visitors to objects carrying out mass events passing through checkpoints. The mathematical model is based on the non-stationary queuing system (NQS) where dependence of requests input rate from time is described by the function. This function was chosen in such way that its properties were similar to the real dependencies of speed of visitors arrival on football matches to the stadium. A piecewise-constant approximation of the function is used when statistical modeling of NQS performing. Authors calculated the dependencies of the queue length and waiting time for visitors to service (time in queue) on time for different laws. Time required to service the entire queue and the number of visitors entering the stadium at the beginning of the match were calculated too. We found the dependence for macroscopic quantitative characteristics of NQS from the number of averaging sections of the input rate.
A game-theoretic approach to real-time system testing
DEFF Research Database (Denmark)
David, Alexandre; Larsen, Kim Guldstrand; Li, Shuhao
2008-01-01
This paper presents a game-theoretic approach to the testing of uncontrollable real-time systems. By modelling the systems with Timed I/O Game Automata and specifying the test purposes as Timed CTL formulas, we employ a recently developed timed game solver UPPAAL-TIGA to synthesize winning...
Adaptive optimization for active queue management supporting TCP flows
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
A unifying conservation law for single server queues.
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
A tandem queue with server slow-down and blocking
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
A tandem queue with server slow-down and blocking.
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
Quasi-stationary analysis for queues with temporary overload
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
Decomposability queueing and computer system applications
Courtois, P J
1977-01-01
Decomposability: Queueing and Computer System Applications presents a set of powerful methods for systems analysis. This 10-chapter text covers the theory of nearly completely decomposable systems upon which specific analytic methods are based.The first chapters deal with some of the basic elements of a theory of nearly completely decomposable stochastic matrices, including the Simon-Ando theorems and the perturbation theory. The succeeding chapters are devoted to the analysis of stochastic queuing networks that appear as a type of key model. These chapters also discuss congestion problems in
On the calculation of steady-state loss probabilities in the GI/G/2/0 queue
Directory of Open Access Journals (Sweden)
Igor N. Kovalenko
1994-01-01
Full Text Available This paper considers methods for calculating the steady-state loss probability in the GI/G/2/0 queue. A previous study analyzed this queue in discrete time and this led to an efficient, numerical approximation scheme for continuous-time systems. The primary aim of the present work is to provide an alternative approach by analyzing the GI/ME/2/0 queue; i.e., assuming that the service time can be represented by a matrix-exponential distribution. An efficient computational scheme based on this method is developed and some numerical examples are studied. Some comparisons are made with the discrete-time approach, and the two methods are seen to be complementary.
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.
A spectral theory approach for extreme value analysis in a tandem of fluid queues
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.
Transient solution of an M/M/1 vacation queue with a waiting server and impatient customers
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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.
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...
Performance optimization of queueing systems with perturbation realization
Xia, Li
2012-04-01
After the intensive studies of queueing theory in the past decades, many excellent results in performance analysis have been obtained, and successful examples abound. However, exploring special features of queueing systems directly in performance optimization still seems to be a territory not very well cultivated. Recent progresses of perturbation analysis (PA) and sensitivity-based optimization provide a new perspective of performance optimization of queueing systems. PA utilizes the structural information of queueing systems to efficiently extract the performance sensitivity information from a sample path of system. This paper gives a brief review of PA and performance optimization of queueing systems, focusing on a fundamental concept called perturbation realization factors, which captures the special dynamic feature of a queueing system. With the perturbation realization factors as building blocks, the performance derivative formula and performance difference formula can be obtained. With performance derivatives, gradient-based optimization can be derived, while with performance difference, policy iteration and optimality equations can be derived. These two fundamental formulas provide a foundation for performance optimization of queueing systems from a sensitivity-based point of view. We hope this survey may provide some inspirations on this promising research topic. © 2011 Elsevier B.V. All rights reserved.
Probability, statistics and queueing theory, with computer science applications
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
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...
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...
Fast distributed strategic learning for global optima in queueing access games
Tembine, Hamidou
2014-08-24
In this paper we examine combined fully distributed payoff and strategy learning (CODIPAS) in a queue-aware access game over a graph. The classical strategic learning analysis relies on vanishing or small learning rate and uses stochastic approximation tool to derive steady states and invariant sets of the underlying learning process. Here, the stochastic approximation framework does not apply due to non-vanishing learning rate. We propose a direct proof of convergence of the process. Interestingly, the convergence time to one of the global optima is almost surely finite and we explicitly characterize the convergence time. We show that pursuit-based CODIPAS learning is much faster than the classical learning algorithms in games. We extend the methodology to coalitional learning and proves a very fast formation of coalitions for queue-aware access games where the action space is dynamically changing depending on the location of the user over a graph.
On buffer overflow duration in a finite-capacity queueing system with multiple vacation policy
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.
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.
Simple queueing approach to segregation dynamics in Schelling model
Sobkowicz, Pawel
2007-01-01
A simple queueing approach for segregation of agents in modified one dimensional Schelling segregation model is presented. The goal is to arrive at simple formula for the number of unhappy agents remaining after the segregation.
A Report on Stochastic Fairness Queueing (SFQ) Experiments
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
An asymptotic analysis of closed queueing networks with branching populations
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...
A message queue based event notification system : football lottery system
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. ...
Consciousness induced restoration of time symmetry (CIRTS): a psychophysical theoretical perspective
Bierman, D.J.
2010-01-01
A theoretical framework is proposed that starts from the assumption that information processing by a brain, while it is sustaining consciousness, is restoring the break in time symmetry in physics. No specifics are given with regard to which physical formalism, either quantum or classical, is the
International Nuclear Information System (INIS)
Lee, W.W.
2003-01-01
Particle simulation has played an important role for the recent investigations on turbulence in magnetically confined plasmas. In this paper, theoretical and numerical properties of a gyrokinetic plasma as well as its relationship with magnetohydrodynamics (MHD) are discussed with the ultimate aim of simulating microturbulence in transport time scale using massively parallel computers
Theoretical analysis of time delays and streaking effects in XUV photoionization
Su, Jing; Ni, Hongcheng; Becker, Andreas; Jaron-Becker, Agnieszka
2013-01-01
We apply a recently proposed theoretical concept and numerical approach to obtain time delays in extreme ultraviolet (XUV) photoionization of an electron in a short- or long-range potential. The results of our numerical simulations on a space-time grid are compared to those for the well-known Wigner-Smith time delay and different methods to obtain the latter time delay are reviewed. We further use our numerical method to analyze the effect of a near-infrared streaking field on the time delay ...
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.
Increasing available FIFO space to prevent messaging queue deadlocks in a DMA environment
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.
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.
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
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.
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.
DEFF Research Database (Denmark)
Fosgerau, Mogens
2010-01-01
This paper investigates the distribution of delays during a repeatedly occurring demand peak in a congested facility with random capacity and demand, such as an airport or an urban road. Congestion is described in the form of a dynamic queue using the Vickrey bottleneck model and assuming Nash...... phenomenon that has now been observed a number of times. Empirical illustration is provided....
Directory of Open Access Journals (Sweden)
LIU Xin-you
2011-06-01
Full Text Available Theoretical prediction provides basic understanding and guidance to correctly implement a certaintechnology in the production process. The present study uses a differential equation to predict the heattransfer time between the surface and core layer of wood during the heat treatment, with applicability inestimating the duration of heat treatments at high temperatures. The obtained prediction was compared withthe result of an experimental study performed on Chinese poplar wood with various thicknesses (20, 40 and60mm. During this experiment, the time necessary for the core of wood to reach a temperature of 100°C,130°C and finally 180°C was monitored and the recorded values were compared with the predicted ones.The result of this comparison proved that the experimental values matched the theoretically predicted times,validating thus the applicability of the proposed equation as prediction tool.
Yang, Run-Qiu; Niu, Chao; Zhang, Cheng-Yong; Kim, Keun-Young
2018-02-01
We compute the time-dependent complexity of the thermofield double states by four different proposals: two holographic proposals based on the "complexity-action" (CA) conjecture and "complexity-volume" (CV) conjecture, and two quantum field theoretic proposals based on the Fubini-Study metric (FS) and Finsler geometry (FG). We find that four different proposals yield both similarities and differences, which will be useful to deepen our understanding on the complexity and sharpen its definition. In particular, at early time the complexity linearly increase in the CV and FG proposals, linearly decreases in the FS proposal, and does not change in the CA proposal. In the late time limit, the CA, CV and FG proposals all show that the growth rate is 2 E/(πℏ) saturating the Lloyd's bound, while the FS proposal shows the growth rate is zero. It seems that the holographic CV conjecture and the field theoretic FG method are more correlated.
Modeling an Application's Theoretical Minimum and Average Transactional Response Times
Energy Technology Data Exchange (ETDEWEB)
Paiz, Mary Rose [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-04-01
The theoretical minimum transactional response time of an application serves as a ba- sis for the expected response time. The lower threshold for the minimum response time represents the minimum amount of time that the application should take to complete a transaction. Knowing the lower threshold is beneficial in detecting anomalies that are re- sults of unsuccessful transactions. On the converse, when an application's response time falls above an upper threshold, there is likely an anomaly in the application that is causing unusual performance issues in the transaction. This report explains how the non-stationary Generalized Extreme Value distribution is used to estimate the lower threshold of an ap- plication's daily minimum transactional response time. It also explains how the seasonal Autoregressive Integrated Moving Average time series model is used to estimate the upper threshold for an application's average transactional response time.
A queueing theory description of fat-tailed price returns in imperfect financial markets
Lamba, H.
2010-09-01
In a financial market, for agents with long investment horizons or at times of severe market stress, it is often changes in the asset price that act as the trigger for transactions or shifts in investment position. This suggests the use of price thresholds to simulate agent behavior over much longer timescales than are currently used in models of order-books. We show that many phenomena, routinely ignored in efficient market theory, can be systematically introduced into an otherwise efficient market, resulting in models that robustly replicate the most important stylized facts. We then demonstrate a close link between such threshold models and queueing theory, with large price changes corresponding to the busy periods of a single-server queue. The distribution of the busy periods is known to have excess kurtosis and non-exponential decay under various assumptions on the queue parameters. Such an approach may prove useful in the development of mathematical models for rapid deleveraging and panics in financial markets, and the stress-testing of financial institutions.
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.
Sample correlations of infinite variance time series models: an empirical and theoretical study
Directory of Open Access Journals (Sweden)
Jason Cohen
1998-01-01
Full Text Available When the elements of a stationary ergodic time series have finite variance the sample correlation function converges (with probability 1 to the theoretical correlation function. What happens in the case where the variance is infinite? In certain cases, the sample correlation function converges in probability to a constant, but not always. If within a class of heavy tailed time series the sample correlation functions do not converge to a constant, then more care must be taken in making inferences and in model selection on the basis of sample autocorrelations. We experimented with simulating various heavy tailed stationary sequences in an attempt to understand what causes the sample correlation function to converge or not to converge to a constant. In two new cases, namely the sum of two independent moving averages and a random permutation scheme, we are able to provide theoretical explanations for a random limit of the sample autocorrelation function as the sample grows.
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.
Parallel discrete-event simulation of FCFS stochastic queueing networks
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.
Research on a Queue Scheduling Algorithm in Wireless Communications Network
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.
An introduction to queueing theory modeling and analysis in applications
Bhat, U Narayan
2015-01-01
This introductory textbook is designed for a one-semester course on queueing theory that does not require a course on stochastic processes as a prerequisite. By integrating the necessary background on stochastic processes with the analysis of models, the work provides a sound foundational introduction to the modeling and analysis of queueing systems for a wide interdisciplinary audience of students in mathematics, statistics, and applied disciplines such as computer science, operations research, and engineering. This edition includes additional topics in methodology and applications. Key features: • An introductory chapter including a historical account of the growth of queueing theory in more than 100 years. • A modeling-based approach with emphasis on identification of models. • Rigorous treatment of the foundations of basic models commonly used in applications with appropriate references for advanced topics. • Applications in manufacturing and, computer and communication systems. • A chapter on ...
Approximate Analysis of an Unreliable M/M/2 Retrial Queue
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
International Nuclear Information System (INIS)
Avenhaus, R.
1992-01-01
In the beginning of nuclear material safeguards, emphasis was placed on safe detection of diversion of nuclear material. Later, the aspect of timely detection became equally important. Since there is a trade-off between these two objectives, the question of an appropriate compromise was raised. In this paper, a decision theoretical framework is presented in which the objectives of the two players, inspector and inspectee, are expressed in terms of general utility functions. Within this framework, optimal safeguards strategies are defined, and furthermore, conditions are formulated under which the optimization criteria corresponding to the objectives mentioned above can be justified
Exploring super-gaussianity towards robust information-theoretical time delay estimation
DEFF Research Database (Denmark)
Petsatodis, Theodoros; Talantzis, Fotios; Boukis, Christos
2013-01-01
Time delay estimation (TDE) is a fundamental component of speaker localization and tracking algorithms. Most of the existing systems are based on the generalized cross-correlation method assuming gaussianity of the source. It has been shown that the distribution of speech, captured with far...... the effect upon TDE when modeling the source signal with different speech-based distributions. An information theoretical TDE method indirectly encapsulating higher order statistics (HOS) formed the basis of this work. The underlying assumption of Gaussian distributed source has been replaced...
Bender, Andrea; Beller, Sieghard
2014-09-01
When speaking and reasoning about time, people around the world tend to do so with vocabulary and concepts borrowed from the domain of space. This raises the question of whether the cross-linguistic variability found for spatial representations, and the principles on which these are based, may also carry over to the domain of time. Real progress in addressing this question presupposes a taxonomy for the possible conceptualizations in one domain and its consistent and comprehensive mapping onto the other-a challenge that has been taken up only recently and is far from reaching consensus. This article aims at systematizing the theoretical and empirical advances in this field, with a focus on accounts that deal with frames of reference (FoRs). It reviews eight such accounts by identifying their conceptual ingredients and principles for space-time mapping, and it explores the potential for their integration. To evaluate their feasibility, data from some thirty empirical studies, conducted with speakers of sixteen different languages, are then scrutinized. This includes a critical assessment of the methods employed, a summary of the findings for each language group, and a (re-)analysis of the data in view of the theoretical questions. The discussion relates these findings to research on the mental time line, and explores the psychological reality of temporal FoRs, the degree of cross-domain consistency in FoR adoption, the role of deixis, and the sources and extent of space-time mapping more generally. Copyright © 2014 Elsevier B.V. All rights reserved.
A game theoretic approach to a finite-time disturbance attenuation problem
Rhee, Ihnseok; Speyer, Jason L.
1991-01-01
A disturbance attenuation problem over a finite-time interval is considered by a game theoretic approach where the control, restricted to a function of the measurement history, plays against adversaries composed of the process and measurement disturbances, and the initial state. A zero-sum game, formulated as a quadratic cost criterion subject to linear time-varying dynamics and measurements, is solved by a calculus of variation technique. By first maximizing the quadratic cost criterion with respect to the process disturbance and initial state, a full information game between the control and the measurement residual subject to the estimator dynamics results. The resulting solution produces an n-dimensional compensator which expresses the controller as a linear combination of the measurement history. A disturbance attenuation problem is solved based on the results of the game problem. For time-invariant systems it is shown that under certain conditions the time-varying controller becomes time-invariant on the infinite-time interval. The resulting controller satisfies an H(infinity) norm bound.
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.
Overflow behavoir in queues with many long-tailed inputs
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
Estimation of the workload correlation in a Markov fluid queue
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
Multi-Resource Fair Queueing for Packet Processing
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
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 ...
Arrival first queueing networks with applications in kanban production systems
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
Arrival first queueing networks with applications in kanban production systems
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
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:
Efficient Simulation of Population Overflow in Parallel Queues
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
Method, apparatus and system for managing queue operations of a test bench environment
Ostler, Farrell Lynn
2016-07-19
Techniques and mechanisms for performing dequeue operations for agents of a test bench environment. In an embodiment, a first group of agents are each allocated a respective ripe reservation and a second set of agents are each allocated a respective unripe reservation. Over time, queue management logic allocates respective reservations to agents and variously changes one or more such reservations from unripe to ripe. In another embodiment, an order of servicing agents allocated unripe reservations is based on relative priorities of the unripe reservations with respect to one another. An order of servicing agents allocated ripe reservations is on a first come, first served basis.
Computational Approach to Profit Optimization of a Loss-Queueing System
Directory of Open Access Journals (Sweden)
Dinesh Kumar Yadav
2010-01-01
Full Text Available Objective of the paper is to deal with the profit optimization of a loss queueing system with the finite capacity. Here, we define and compute total expected cost (TEC, total expected revenue (TER and consequently we compute the total optimal profit (TOP of the system. In order to compute the total optimal profit of the system, a computing algorithm has been developed and a fast converging N-R method has been employed which requires least computing time and lesser memory space as compared to other methods. Sensitivity analysis and its observations based on graphics have added a significant value to this model.
A Game-Theoretic Approach to Branching Time Abstract-Check-Refine Process
Wang, Yi; Tamai, Tetsuo
2009-01-01
Since the complexity of software systems continues to grow, most engineers face two serious problems: the state space explosion problem and the problem of how to debug systems. In this paper, we propose a game-theoretic approach to full branching time model checking on three-valued semantics. The three-valued models and logics provide successful abstraction that overcomes the state space explosion problem. The game style model checking that generates counter-examples can guide refinement or identify validated formulas, which solves the system debugging problem. Furthermore, output of our game style method will give significant information to engineers in detecting where errors have occurred and what the causes of the errors are.
Efficient simulation of finite horizon problems in queueing and insurance risk
DEFF Research Database (Denmark)
Rojas-Nandayapa, Leonardo; Asmussen, Søren
Let ψ(u, t) be the probability that the workload in an initially empty M/G/1 queue exceeds u at time t < ∞, or, equivalently, the ruin probability in the classical Crámer-Lundberg model. Assuming service times/claim sizes to be subexponential, various Monte Carlo estimators for ψ(u, t) are sugges......Let ψ(u, t) be the probability that the workload in an initially empty M/G/1 queue exceeds u at time t classical Crámer-Lundberg model. Assuming service times/claim sizes to be subexponential, various Monte Carlo estimators for ψ(u, t......) are suggested. A key idea behind the estimators is conditional Monte Carlo. Variance estimates are derived in the regularly varying case, the eﬃciencies are compared numerically and also one of the estimators is shown to have bounded relative error. In part, also extensions to general Lévy processes are treated....
Design of Active Queue Management for Robust Control on Access Router for Heterogeneous Networks
Directory of Open Access Journals (Sweden)
Åhlund Christer
2011-01-01
Full Text Available The Internet architecture is a packet switching technology that allows dynamic sharing of bandwidth among different flows with in an IP network. Packets are stored and forwarded from one node to the next until reaching their destination. Major issues in this integration are congestion control and how to meet different quality of service requirements associated with various services. In other words streaming media quality degrades with increased packet delay and jitter caused by network congestion. To mitigate the impact of network congestion, various techniques have been used to improve multimedia quality and one of those techniques is Active Queue Management (AQM. Access routers require a buffer to hold packets during times of congestion. A large buffer can absorb the bursty arrivals, and this tends to increase the link utilizations but results in higher queuing delays. Traffic burstiness has a considerable negative impact on network performance. AQM is now considered an effective congestion control mechanism for enhancing transport protocol performance over wireless links. In order to have good link utilization, it is necessary for queues to adapt to varying traffic loads. This paper considers a particular scheme which is called Adaptive AQM (AAQM and studies its performance in the presence of feedback delays and its ability to maintain a small queue length as well as its robustness in the presence of traffic burstiness. The paper also presents a method based on the well-known Markov Modulated Poisson Process (MPP to capture traffic burstiness and buffer occupancy. To demonstrate the generality of the presented method, an analytic model is described and verified by extensive simulations of different adaptive AQM algorithms. The analysis and simulations show that AAQM outperforms the other AQMs with respect to responsiveness and robustness.
Competing for jobs: labor queues and gender sorting in the hiring process.
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.
Theoretical determination of chemical rate constants using novel time-dependent methods
Dateo, Christopher E.
1994-01-01
The work completed within the grant period 10/1/91 through 12/31/93 falls primarily in the area of reaction dynamics using both quantum and classical mechanical methodologies. Essentially four projects have been completed and have been or are in preparation of being published. The majority of time was spent in the determination of reaction rate coefficients in the area of hydrocarbon fuel combustion reactions which are relevant to NASA's High Speed Research Program (HSRP). These reaction coefficients are important in the design of novel jet engines with low NOx emissions, which through a series of catalytic reactions contribute to the deterioration of the earth's ozone layer. A second area of research studied concerned the control of chemical reactivity using ultrashort (femtosecond) laser pulses. Recent advances in pulsed-laser technologies have opened up a vast new field to be investigated both experimentally and theoretically. The photodissociation of molecules adsorbed on surfaces using novel time-independent quantum mechanical methods was a third project. And finally, using state-of-the-art, high level ab initio electronic structure methods in conjunction with accurate quantum dynamical methods, the rovibrational energy levels of a triatomic molecule with two nonhydrogen atoms (HCN) were calculated to unprecedented levels of agreement between theory and experiment.
Elements of queueing theory palm martingale calculus and stochastic recurrences
Baccelli, François
2003-01-01
The Palm theory and the Loynes theory of stationary systems are the two pillars of the modern approach to queuing. This book, presenting the mathematical foundations of the theory of stationary queuing systems, contains a thorough treatment of both of these. This approach helps to clarify the picture, in that it separates the task of obtaining the key system formulas from that of proving convergence to a stationary state and computing its law. The theory is constantly illustrated by classical results and models: Pollaczek-Khintchin and Tacacs formulas, Jackson and Gordon-Newell networks, multiserver queues, blocking queues, loss systems etc., but it also contains recent and significant examples, where the tools developed turn out to be indispensable. Several other mathematical tools which are useful within this approach are also presented, such as the martingale calculus for point processes, or stochastic ordering for stationary recurrences. This thoroughly revised second edition contains substantial addition...
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.
Do Informal Workers Queue For Formal Jobs in Brazil ?
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 ...
The queue as a social statement / Maria-Kristiina Soomre
Soomre, Maria-Kristiina, 1978-
2010-01-01
Tallinna Lauluväljakul veebruaris 2010 olnud töötute järjekorrast, kus 5000-st said alternatiivse töö reisisaatjatena 400. Keskerakonna kampaaniatest, mida võib vaadata sotsiaalse kunsti kontekstis. Sügisel 2010 Tallinna Kunstihoone juures korraldatud kunstiprojektist "Art Queue 100x100 EEK", millega sooviti tõmmata tähelepanu kunstiinstitutsioonile. Seoses kunstiga tekkinud järjekordadest, masside valmidusest kampaania korras rünnata kunsti
A Game Theoretic Approach to Minimize the Completion Time of Network Coded Cooperative Data Exchange
Douik, Ahmed S.
2014-05-11
In this paper, we introduce a game theoretic framework for studying the problem of minimizing the completion time of instantly decodable network coding (IDNC) for cooperative data exchange (CDE) in decentralized wireless network. In this configuration, clients cooperate with each other to recover the erased packets without a central controller. Game theory is employed herein as a tool for improving the distributed solution by overcoming the need for a central controller or additional signaling in the system. We model the session by self-interested players in a non-cooperative potential game. The utility function is designed such that increasing individual payoff results in a collective behavior achieving both a desirable system performance in a shared network environment and the Pareto optimal solution. Through extensive simulations, our approach is compared to the best performance that could be found in the conventional point-to-multipoint (PMP) recovery process. Numerical results show that our formulation largely outperforms the conventional PMP scheme in most practical situations and achieves a lower delay.
Tijms, H.C.; van der Duyn Schouten, F.A.
1978-01-01
This paper deals with inventory control in a class of M/G/1 queueing systems. At each point of time the system can be switched from one of two possible stages to another. The rate of arrival process and the service rate depend on the stage of the system. The cost structure imposed on the model
International Nuclear Information System (INIS)
Soumya, Elabed; Saad, Ibnsouda Koraichi; Abdellah, Houari; Hassan, Latrache
2013-01-01
In this study, the adhesion of 4 Penicillium strains (Penicillium granulatum, Penicillium crustosum, Penicillium commune and Penicillium chrysogenum) on cedar wood was examined qualitatively and quantitatively by using the extended DLVO (XDLVO) approach and the environmental scanning electronic microscopy (ESEM) technique. A comparison between the XDLVO theories and the ESEM technique was also investigated. The adhesion tests revealed that P. chrysogenum was not able to adhere on the cedar wood substrata, as predicted by the XDLVO approach. We have also found by ESEM that the three Penicillium strains (P. granulatum, P. crustosum, P. commune) adhered on wood, as not predicted theoretically. Moreover, the time of adhesion (3 h and 24 h) was used not only to compare the capacity of adhesion according to contact time but also to explain the discrepancies between the XDLVO approach prediction and the adhesion experiments. A positive relationship between the XDLVO approach and adhesion experiments has been observed after 3 h of adhesion. In contrast, a contradiction between the XDLVO predictions and the adhesion test results has been noted after 24 h of adhesion of Penicillium strains to the wood surface. Highlights: ► Calculation of free energy of adhesion to cedar wood of Penicillium by XDLVO approach ► Adhesion is not favorable for all Penicillium spores–cedar wood combinations. ► Adhesion tests demonstrated the ability of Penicillium spores to adhere to cedar wood. ► XDLVO approach correlated well with the results obtained after 3 h of adhesion. ► Discrepancy between XDLVO predictions and experimental observations at 24 h of adhesion
Energy Technology Data Exchange (ETDEWEB)
Soumya, Elabed [Laboratoire de Biotechnologie Microbienne, Faculté des Sciences et Techniques de Fès-Saïs (Morocco); Université Sidi Mohamed Ben Abdellah, Centre Universitaire Régional d' Interface-Fès (Morocco); Saad, Ibnsouda Koraichi, E-mail: ibnsouda@hotmail.com [Laboratoire de Biotechnologie Microbienne, Faculté des Sciences et Techniques de Fès-Saïs (Morocco); Université Sidi Mohamed Ben Abdellah, Centre Universitaire Régional d' Interface-Fès (Morocco); Abdellah, Houari [Laboratoire de Biotechnologie Microbienne, Faculté des Sciences et Techniques de Fès-Saïs (Morocco); Hassan, Latrache [Laboratoire de Valorisation et de Sécurité des Produits Agroalimentaires, Faculté des Sciences et Techniques de Beni Mellal (Morocco)
2013-04-01
In this study, the adhesion of 4 Penicillium strains (Penicillium granulatum, Penicillium crustosum, Penicillium commune and Penicillium chrysogenum) on cedar wood was examined qualitatively and quantitatively by using the extended DLVO (XDLVO) approach and the environmental scanning electronic microscopy (ESEM) technique. A comparison between the XDLVO theories and the ESEM technique was also investigated. The adhesion tests revealed that P. chrysogenum was not able to adhere on the cedar wood substrata, as predicted by the XDLVO approach. We have also found by ESEM that the three Penicillium strains (P. granulatum, P. crustosum, P. commune) adhered on wood, as not predicted theoretically. Moreover, the time of adhesion (3 h and 24 h) was used not only to compare the capacity of adhesion according to contact time but also to explain the discrepancies between the XDLVO approach prediction and the adhesion experiments. A positive relationship between the XDLVO approach and adhesion experiments has been observed after 3 h of adhesion. In contrast, a contradiction between the XDLVO predictions and the adhesion test results has been noted after 24 h of adhesion of Penicillium strains to the wood surface. Highlights: ► Calculation of free energy of adhesion to cedar wood of Penicillium by XDLVO approach ► Adhesion is not favorable for all Penicillium spores–cedar wood combinations. ► Adhesion tests demonstrated the ability of Penicillium spores to adhere to cedar wood. ► XDLVO approach correlated well with the results obtained after 3 h of adhesion. ► Discrepancy between XDLVO predictions and experimental observations at 24 h of adhesion.
Many-server queues with customer abandonment: Numerical analysis of their diffusion model
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...
On a tandem queue with batch service and its applications in wireless sensor networks
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
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.
Energy Technology Data Exchange (ETDEWEB)
Niez, J.J
2000-07-01
One describes here the theoretical tools which are needed for evaluating the nuclear lifetime of a nucleus dipped into electromagnetic surroundings which are composed of electrons and photons. The case where this environment is a material or a cavity will be treated in a following report. (Author)
Time To Speak Up: A Theoretical Framework of Situated Pedagogy and Practice for Communication.
Dannels, Deanna P.
2001-01-01
Discusses a theoretical framework of situated pedagogy and practice for communication across the curriculum (CXC). Gives principles of a situated communication pedagogy. Examines implications of a situated communication pedagogy for communication in the disciplines (CID) practice. Notes the benefits of a situated communication pedagogy and…
Directory of Open Access Journals (Sweden)
Dusan Popov
2013-09-01
Full Text Available In the paper, the reverberation phenomenon produced by the harmonic emission of a sound source is theoretically examined, taking into consideration the absorption of the sound in the air. We obtain a formula which contains, as particular cases, the similar formulae presented in the literature.
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 ...
Analysis of a generalized shortest queue system by flexible bound models
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.
On a tandem queue with batch service and its applications in wireless sensor networks
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 μ_{0}, ⋯ , μ_{s} _{-} _{1}. Service process i, i= 0 , ⋯ , s- 1 , at rate
Efficient Heuristics for the Simulation of Buffer Overflow in Series and Parallel Queueing Networks
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 overï¬‚ow 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
Request queues for interactive clients in a shared file system of a parallel computing system
Bent, John M.; Faibish, Sorin
2015-08-18
Interactive requests are processed from users of log-in nodes. A metadata server node is provided for use in a file system shared by one or more interactive nodes and one or more batch nodes. The interactive nodes comprise interactive clients to execute interactive tasks and the batch nodes execute batch jobs for one or more batch clients. The metadata server node comprises a virtual machine monitor; an interactive client proxy to store metadata requests from the interactive clients in an interactive client queue; a batch client proxy to store metadata requests from the batch clients in a batch client queue; and a metadata server to store the metadata requests from the interactive client queue and the batch client queue in a metadata queue based on an allocation of resources by the virtual machine monitor. The metadata requests can be prioritized, for example, based on one or more of a predefined policy and predefined rules.
Delay Variation Model with Two Service Queues
Directory of Open Access Journals (Sweden)
Filip Rezac
2010-01-01
Full Text Available Delay in VoIP technology is very unpleasant issue and therefore a voice packets prioritization must be ensured. To maintain the high call quality a maximum information delivery time from the sender to the recipient is set to 150 ms. This paper focuses on the design of a mathematical model of end-to-end delay of a VoIP connection, in particular on a delay variation. It describes all partial delay components and mechanisms, their generation, facilities and mathematical formulations. A new approach to the delay variation model is presented and its validation has been done by experimention.
Ito, Masahito; Shimizu, Katsutoshi; Nakatani, Kiyoharu
2018-01-01
There has been considerable discussion of the speed performance of HPLC separation, especially regarding the relationship between theoretical plates and hold-up time. The fundamental discussion focuses on the optimal velocity, u 0,opt , which gives a minimal height equivalent to a theoretical plate of the van Deemter plot. On the other hand, Desmet's method, using the kinetic performance limit (KPL), calculates the highest performance with a constant pressure drop, without focusing solely on the optimal velocity. In this paper, a precise method based on the KPL is proposed, to understand how increasing pressure enhances both theoretical plates and hold-up time. A three-dimensional representation method that combines the pressure drop with two axes of time and theoretical plates will be useful for discussing the effect of pressure in pressure-driven chromatography. Using three dimensions, the methods based on u 0,opt and the KPL can be combined, because u 0,opt can be visualized three-dimensionally, including the neighbor of u 0,opt ; and the question of whether the KPL is an asymptotic or effective limit can be investigated. Three performances of high resolution, high speed, and low pressure can be understood on different packing supports at a glance.
Razumchik, Rostislav R.
2017-07-01
Consideration is given to M|G|1 queueing system with inverse service order and probabilistic priority. Customers arrive in batches and the arrival rate depends on the total number of customers in the system. The size of the batch and the service times of the customers in the batch are governed by a given joint probability distribution. It is shown that the joint probability distribution of the total number of customers in the system and the remaining service time of the customer in service can be obtained as a solution of the system of integro-differential equations. The solution can be performed in a recursive way.
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...
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.
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.
Theoretical study of built-in-polarization effect on relaxation time and ...
Indian Academy of Sciences (India)
tion. The combined relaxation time due to above-mentioned scattering mechanisms has also been computed as a function of phonon frequency for various Al compositions at room temperature. It is found that combined relaxation time is enhanced due to built-in-polarization effect and makes phonon mean free path longer, ...
Goren, Liran
2016-10-01
The fluvial response time dictates the duration of fluvial channel adjustment in response to changing climatic and tectonic conditions. However, when these conditions vary continuously, the channel cannot equilibrate and the response time is not well defined. Here I develop an analytical solution to the linear stream power model of fluvial incision that predicts the channel topography as a function of time-dependent climatic and tectonic conditions. From this solution, a general definition of the fluvial response time emerges: the duration over which the tectonic history needs to be known to evaluate channel topography. This new definition is used in linear inversion schemes for inferring climatic or tectonic histories from river long profiles. The analytic solution further reveals that high-frequency climatic oscillations, such as Milankovitch cycles, are not expected to leave significant fingerprints on the long profiles of fluvially incised detachment-limited rivers.
System-theoretic analysis of due-time performance in production systems
Directory of Open Access Journals (Sweden)
Jacobs David
1995-01-01
Full Text Available Along with the average production rate, the due-time performance is an important characteristic of manufacturing systems. Unlike the production rate, the due-time performance has received relatively little attention in the literature, especially in the context of large volume production. This paper is devoted to this topic. Specifically, the notion of due-time performance is formalized as the probability that the number of parts produced during the shipping period reaches the required shipment size. This performance index is analyzed for both lean and mass manufacturing environments. In particular, it is shown that, to achieve a high due-time performance in a lean environment, the production system should be scheduled for a sufficiently small fraction of its average production rate. In mass production, due-time performance arbitrarily close to one can be achieved for any scheduling practice, up to the average production rate.
Autonomous Hybrid Priority Queueing for Scheduling Residential Energy Demands
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.
An emergency department patient flow model based on queueing theory principles.
Wiler, Jennifer L; Bolandifar, Ehsan; Griffey, Richard T; Poirier, Robert F; Olsen, Tava
2013-09-01
The objective was to derive and validate a novel queuing theory-based model that predicts the effect of various patient crowding scenarios on patient left without being seen (LWBS) rates. Retrospective data were collected from all patient presentations to triage at an urban, academic, adult-only emergency department (ED) with 87,705 visits in calendar year 2008. Data from specific time windows during the day were divided into derivation and validation sets based on odd or even days. Patient records with incomplete time data were excluded. With an established call center queueing model, input variables were modified to adapt this model to the ED setting, while satisfying the underlying assumptions of queueing theory. The primary aim was the derivation and validation of an ED flow model. Chi-square and Student's t-tests were used for model derivation and validation. The secondary aim was estimating the effect of varying ED patient arrival and boarding scenarios on LWBS rates using this model. The assumption of stationarity of the model was validated for three time periods (peak arrival rate = 10:00 a.m. to 12:00 p.m.; a moderate arrival rate = 8:00 a.m. to 10:00 a.m.; and lowest arrival rate = 4:00 a.m. to 6:00 a.m.) and for different days of the week and month. Between 10:00 a.m. and 12:00 p.m., defined as the primary study period representing peak arrivals, 3.9% (n = 4,038) of patients LWBS. Using the derived model, the predicted LWBS rate was 4%. LWBS rates increased as the rate of ED patient arrivals, treatment times, and ED boarding times increased. A 10% increase in hourly ED patient arrivals from the observed average arrival rate increased the predicted LWBS rate to 10.8%; a 10% decrease in hourly ED patient arrivals from the observed average arrival rate predicted a 1.6% LWBS rate. A 30-minute decrease in treatment time from the observed average treatment time predicted a 1.4% LWBS. A 1% increase in patient arrivals has the same effect on LWBS rates as a 1
Theoretical study of time-dependent, ultrasound-induced acoustic streaming in microchannels
DEFF Research Database (Denmark)
Muller, Peter Barkholt; Bruus, Henrik
2015-01-01
Based on first- and second-order perturbation theory, we present a numerical study of the temporal buildup and decay of unsteady acoustic fields and acoustic streaming flows actuated by vibrating walls in the transverse cross-sectional plane of a long straight microchannel under adiabatic...... conditions and assuming temperature-independent material parameters. The unsteady streaming flow is obtained by averaging the time-dependent velocity field over one oscillation period, and as time increases, it is shown to converge towards the well-known steady time-averaged solution calculated...... in the frequency domain. Scaling analysis reveals that the acoustic resonance builds up much faster than the acoustic streaming, implying that the radiation force may dominate over the drag force from streaming even for small particles. However, our numerical time-dependent analysis indicates that pulsed actuation...
Theoretical study of time-dependent, ultrasound-induced acoustic streaming in microchannels.
Muller, Peter Barkholt; Bruus, Henrik
2015-12-01
Based on first- and second-order perturbation theory, we present a numerical study of the temporal buildup and decay of unsteady acoustic fields and acoustic streaming flows actuated by vibrating walls in the transverse cross-sectional plane of a long straight microchannel under adiabatic conditions and assuming temperature-independent material parameters. The unsteady streaming flow is obtained by averaging the time-dependent velocity field over one oscillation period, and as time increases, it is shown to converge towards the well-known steady time-averaged solution calculated in the frequency domain. Scaling analysis reveals that the acoustic resonance builds up much faster than the acoustic streaming, implying that the radiation force may dominate over the drag force from streaming even for small particles. However, our numerical time-dependent analysis indicates that pulsed actuation does not reduce streaming significantly due to its slow decay. Our analysis also shows that for an acoustic resonance with a quality factor Q, the amplitude of the oscillating second-order velocity component is Q times larger than the usual second-order steady time-averaged velocity component. Consequently, the well-known criterion v(1)≪c(s) for the validity of the perturbation expansion is replaced by the more restrictive criterion v(1)≪c(s)/Q. Our numerical model is available as supplemental material in the form of comsol model files and matlab scripts.
International Nuclear Information System (INIS)
Grohs, B.
1983-01-01
The ALOK-technique allows the simultaneous detection of flaws and their evaluation with respect to type, location and dimension by interpretation of the transit time behaviour during scanning of the reflector. The accuracy of information obtained by means of this technique can be further improved both during interference elimination and reconstruction owing to the ability of exact calculation of possible transit time locus curves of given reflectors. The mathematical solution of transit time locus curve calculations refers here to pulse echo testing in consideration of the refraction of sound on the forward wedge/test object - interface. The method of solving the problem is equivalent to the Fermat's principle in optics. (orig.) [de
First photon detection in time-resolved transillumination imaging: a theoretical evaluation
International Nuclear Information System (INIS)
Behin-Ain, S; Doorn, T van; Patterson, J R
2004-01-01
First photon detection, as a special case of time-resolved transillumination imaging, is studied through the derivation of the temporal probability density function (pdf) for the first arriving photon. The pdf for different laser intensities, media and second and later arriving photons were generated. The arrival time of the first detected photon reduced as the laser power increased and also when the scattering and absorption coefficients decreased. The pdf for an imbedded totally absorbing 3 mm inhomogeneity may be distinguished from the pdf of a homogeneous turbid medium similar to that of human breast in dimensions and optical properties
Calculation of Additional Lost Green Time at Closely Spaced Intersections
Directory of Open Access Journals (Sweden)
Zhen Zhang
2013-06-01
Full Text Available At closely spaced signalized intersections or interchanges, additional lost green time can occur at upstream intersections when there is a queue spillback. For an accurate estimation of capacities and delays at closely spaced intersections, it is necessary to account such additional lost time. The Highway Capacity Manual (HCM 2010 provides a model for the estimation of the additional lost time due to the presence of a downstream queue. However, case studies indicate that the HCM model does not provide a very accurate estimation when the distance to the downstream queue is short. In this paper, a new model is developed for the estimation of additional lost time considering queue discharge patterns and traffic flow patterns. Simulation results show that the proposed model provides a more accurate estimation of additional lost time compared with the HCM model when the distance to the downstream queue is limited.
Theoretical study of built-in-polarization effect on relaxation time and ...
Indian Academy of Sciences (India)
It is found that combined relaxation time is enhanced due to built-in-polarization effect and makes phonon mean free path longer, which is required forhigher optical, electrical and thermal transport processes. The result can be used to determine the effect of built-inpolarization field on optical and thermal properties of Al x ...
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 ...
Theoretical treatment of photodissociation of water by time-dependent quantum mechanical methods
International Nuclear Information System (INIS)
Weide, K.
1993-01-01
An algorithm for wavepacket propagation, based on Kosloff's method of expansion of the time evolution operator in terms of Chebychev polynomials, and some details of its implementation are described. With the programs developed, quantum-mechanical calculations for up to three independent molecular coordinates are possible and feasible and therefore photodissociation of non-rotating triatomic molecules can be treated exactly. The angular degree of freedom here is handled by expansion in terms of free diatomic rotor states. The time-dependent wave packet picture is compared with the more traditional view of stationary wave functions, and both are used to interpret computational results where appropriate. Two-dimensional calculations have been performed to explain several experimental observations about water photodissociation. All calculations are based on ab initio potential energy surfaces, and it is explained in each case why it is reasonable to neglect the third degree of freedom. Many experimental results are reproduced quantitatively. (orig.) [de
An Excursion-Theoretic Approach to Stability of Discrete-Time Stochastic Hybrid Systems
Energy Technology Data Exchange (ETDEWEB)
Chatterjee, Debasish, E-mail: chatterjee@control.ee.ethz.ch [ETH Zuerich, ETL I19 (Switzerland); Pal, Soumik, E-mail: soumik@math.washington.edu [University of Washington, Department of Mathematics (United States)
2011-04-15
We address stability of a class of Markovian discrete-time stochastic hybrid systems. This class of systems is characterized by the state-space of the system being partitioned into a safe or target set and its exterior, and the dynamics of the system being different in each domain. We give conditions for L{sub 1}-boundedness of Lyapunov functions based on certain negative drift conditions outside the target set, together with some more minor assumptions. We then apply our results to a wide class of randomly switched systems (or iterated function systems), for which we give conditions for global asymptotic stability almost surely and in L{sub 1}. The systems need not be time-homogeneous, and our results apply to certain systems for which functional-analytic or martingale-based estimates are difficult or impossible to get.
Time Analysis of Building Dynamic Response Under Seismic Action. Part 1: Theoretical Propositions
Ufimtcev, E. M.
2017-11-01
The first part of the article presents the main provisions of the analytical approach – the time analysis method (TAM) developed for the calculation of the elastic dynamic response of rod structures as discrete dissipative systems (DDS) and based on the investigation of the characteristic matrix quadratic equation. The assumptions adopted in the construction of the mathematical model of structural oscillations as well as the features of seismic forces’ calculating and recording based on the data of earthquake accelerograms are given. A system to resolve equations is given to determine the nodal (kinematic and force) response parameters as well as the stress-strain state (SSS) parameters of the system’s rods.
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...
Optimization of the ionization time of an atom with tailored laser pulses: a theoretical study
Kammerlander, David; Castro, Alberto; Marques, Miguel A. L.
2017-05-01
How fast can a laser pulse ionize an atom? We address this question by considering pulses that carry a fixed time-integrated energy per-area, and finding those that achieve the double requirement of maximizing the ionization that they induce, while having the shortest duration. We formulate this double-objective quantum optimal control problem by making use of the Pareto approach to multi-objective optimization, and the differential evolution genetic algorithm. The goal is to find out how a precise time-profiling of ultra-fast, large-bandwidth pulses may speed up the ionization process. We work on a simple one-dimensional model of hydrogen-like atoms (the Pöschl-Teller potential) that allows to tune the number of bound states that play a role in the ionization dynamics. We show how the detailed shape of the pulse accelerates the ionization, and how the presence or absence of bound states influences the velocity of the process.
Queueing-theoretic solution methods for models of parallel and distributed systems
O.J. Boxma (Onno); G.M. Koole (Ger); Z. Liu
1994-01-01
textabstractThis paper aims to give an overview of solution methods for the performance analysis of parallel and distributed systems. After a brief review of some important general solution methods, we discuss key models of parallel and distributed systems, and optimization issues, from the
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.
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.
Theoretical study of time-resolved luminescence in semiconductors. III. Trap states in the band gap
International Nuclear Information System (INIS)
Maiberg, Matthias; Hölscher, Torsten; Zahedi-Azad, Setareh; Scheer, Roland
2015-01-01
In the third part of this series, we study the influence of trap states in the band gap of semiconductors on the time-resolved luminescence decay (TRL) after a pulsed excitation. The results based on simulations with Synopsys TCAD ® and analytical approximations are given for p-doped Cu(In,Ga)Se 2 as a working example. We show that a single trap can be mostly described by two parameters which are assigned to minority carrier capture and emission. We analyze their influence on the luminescence decay and study the difference between a single trap and an energetic Gaussian trap distribution. It is found that trap states artificially increase the TRL decay and obscure the recombination dynamics. Thus, there is a demand for experimental methods which can reveal the recombination of minority carriers in a TRL experiment without trapping effect. In this regard, a variation of the device temperature, the excitation frequency, the injection level, as well as a bias illumination may be promising approaches. We study these methods, discuss advantages and disadvantages, and show experimental TRL for prove of concept. At the end, we validate our approach of simulating only band-to-band radiative recombination although photoluminescence spectra often exhibit free-to-bound radiative recombination of charge carriers
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.
Graphene-Based FET Detector for E. coli K12 Real-Time Monitoring and Its Theoretical Analysis
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Jieyi Zhu
2016-01-01
Full Text Available This paper presents a theoretical analysis for a graphene-based FET real-time detector of the target bacteria E. coli K12. The motivation for this study is to design a sensor device for detection of bacteria in food and water in order to guarantee food safety. Graphene is chosen as our material for sensor design, which has outstanding electrical, physical, and optical performance. In our sensor structure, graphene-based solution gate field effect transistor (FET is the device model; fabrication and functionalization protocol are presented together in this paper. What is more, a real-time signal display system is the accompanied equipment for our designed biosensor device. In this system, the sensor bias current signal Ids would change obviously when the target bacteria are attached to the sensor surface. And the bias current Ids increases when the E. coli concentration increases. In the latter part, a theoretical interpretation of the sensor signal is to explain the bias current Ids increasing after the E. coli K12 attachment.
The impact of aviation checkpoint queues on optimizing security screening effectiveness
International Nuclear Information System (INIS)
Lee, Adrian J.; Jacobson, Sheldon H.
2011-01-01
Passenger screening at aviation security checkpoints is a critical component in protecting airports and aircraft from terrorist threats. Recent developments in screening device technology have increased the ability to detect these threats; however, the average amount of time it takes to screen a passenger still remains a concern. This paper models the queueing process for a multi-level airport checkpoint security system, where multiple security classes are formed through subsets of specialized screening devices. An optimal static assignment policy is obtained which minimizes the steady-state expected amount of time a passenger spends in the security system. Then, an optimal dynamic assignment policy is obtained through a transient analysis that balances the expected number of true alarms with the expected amount of time a passenger spends in the security system. Performance of a two-class system is compared to that of a selective security system containing primary and secondary levels of screening. The key contribution is that the resulting optimal assignment policies increase security and passenger throughput by efficiently and effectively utilizing available screening resources.
Wei, Xiaohui; Sun, Bingyi; Cui, Jiaxu; Xu, Gaochao
2016-01-01
As a result of the greatly increased use of mobile devices, the disadvantages of portable devices have gradually begun to emerge. To solve these problems, the use of mobile cloud computing assisted by cloud data centers has been proposed. However, cloud data centers are always very far from the mobile requesters. In this paper, we propose an improved multi-objective local mobile cloud model: Compounded Local Mobile Cloud Architecture with Dynamic Priority Queues (LMCpri). This new architecture could briefly store jobs that arrive simultaneously at the cloudlet in different priority positions according to the result of auction processing, and then execute partitioning tasks on capable helpers. In the Scheduling Module, NSGA-II is employed as the scheduling algorithm to shorten processing time and decrease requester cost relative to PSO and sequential scheduling. The simulation results show that the number of iteration times that is defined to 30 is the best choice of the system. In addition, comparing with LMCque, LMCpri is able to effectively accommodate a requester who would like his job to be executed in advance and shorten execution time. Finally, we make a comparing experiment between LMCpri and cloud assisting architecture, and the results reveal that LMCpri presents a better performance advantage than cloud assisting architecture.
Hartzler, A L; Patel, R A; Czerwinski, M; Pratt, W; Roseway, A; Chandrasekaran, N; Back, A
2014-01-01
This article is part of the focus theme of Methods of Information in Medicine on "Pervasive Intelligent Technologies for Health". Effective nonverbal communication between patients and clinicians fosters both the delivery of empathic patient-centered care and positive patient outcomes. Although nonverbal skill training is a recognized need, few efforts to enhance patient-clinician communication provide visual feedback on nonverbal aspects of the clinical encounter. We describe a novel approach that uses social signal processing technology (SSP) to capture nonverbal cues in real time and to display ambient visual feedback on control and affiliation--two primary, yet distinct dimensions of interpersonal nonverbal communication. To examine the design and clinician acceptance of ambient visual feedback on nonverbal communication, we 1) formulated a model of relational communication to ground SSP and 2) conducted a formative user study using mixed methods to explore the design of visual feedback. Based on a model of relational communication, we reviewed interpersonal communication research to map nonverbal cues to signals of affiliation and control evidenced in patient-clinician interaction. Corresponding with our formulation of this theoretical framework, we designed ambient real-time visualizations that reflect variations of affiliation and control. To explore clinicians' acceptance of this visual feedback, we conducted a lab study using the Wizard-of-Oz technique to simulate system use with 16 healthcare professionals. We followed up with seven of those participants through interviews to iterate on the design with a revised visualization that addressed emergent design considerations. Ambient visual feedback on non- verbal communication provides a theoretically grounded and acceptable way to provide clinicians with awareness of their nonverbal communication style. We provide implications for the design of such visual feedback that encourages empathic patient
Multi stage unreliable retrial Queueing system with Bernoulli vacation
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.
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.
THREE-MOMENT BASED APPROXIMATION OF PROBABILITY DISTRIBUTIONS IN QUEUEING SYSTEMS
Directory of Open Access Journals (Sweden)
T. I. Aliev
2014-03-01
Full Text Available The paper deals with the problem of approximation of probability distributions of random variables defined in positive area of real numbers with coefficient of variation different from unity. While using queueing systems as models for computer networks, calculation of characteristics is usually performed at the level of expectation and variance. At the same time, one of the main characteristics of multimedia data transmission quality in computer networks is delay jitter. For jitter calculation the function of packets time delay distribution should be known. It is shown that changing the third moment of distribution of packets delay leads to jitter calculation difference in tens or hundreds of percent, with the same values of the first two moments – expectation value and delay variation coefficient. This means that delay distribution approximation for the calculation of jitter should be performed in accordance with the third moment of delay distribution. For random variables with coefficients of variation greater than unity, iterative approximation algorithm with hyper-exponential two-phase distribution based on three moments of approximated distribution is offered. It is shown that for random variables with coefficients of variation less than unity, the impact of the third moment of distribution becomes negligible, and for approximation of such distributions Erlang distribution with two first moments should be used. This approach gives the possibility to obtain upper bounds for relevant characteristics, particularly, the upper bound of delay jitter.
Approximate anlysis of an unreliable $M/M/c$ retrial queue with phase merging algorithm.
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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.
Traffic Regulation on Wireless 802.11 Networks Using Multiple Queue Technique
Dhanal, Radhika J.; Patil, G. A.
2010-11-01
WLAN technologies are becoming increasingly popular and are platform for many future applications. IEEE 802.11 Wireless LAN (WLAN) is an excellent solution for the broadband wireless networking. This paper presents a simple approach to enhance the performance of real time (RT) and non-real time (NRT) services over the 802.11 WLAN by using some special queues. This requires the system to first identify the type of service and then use the appropriate scheduling algorithm. The admission control algorithm is used first to determine the admission of particular station. Deficit round robin algorithm is used to set the priorities to RT and NRT packets in order to increase the QoS of WLAN. So we can combine both these algorithms by implementing them one after another. The proposed scheme can improve Voice/Data/Video services through simple software upgrades by reducing the delay, jitter and increasing the throughput. Through simulation, we show that the proposed scheme can give better QoS than existing schemes.
Energy Technology Data Exchange (ETDEWEB)
Pabst, Stefan Ulf
2013-04-15
The concept of atoms as the building blocks of matter has existed for over 3000 years. A revolution in the understanding and the description of atoms and molecules has occurred in the last century with the birth of quantum mechanics. After the electronic structure was understood, interest in studying the dynamics of electrons, atoms, and molecules increased. However, time-resolved investigations of these ultrafast processes were not possible until recently. The typical time scale of atomic and molecular processes is in the picosecond to attosecond realm. Tremendous technological progress in recent years makes it possible to generate light pulses on these time scales. With such ultrashort pulses, atomic and molecular dynamics can be triggered, watched, and controlled. Simultaneously, the need rises for theoretical models describing the underlying mechanisms. This doctoral thesis focuses on the development of theoretical models which can be used to study the dynamical behavior of electrons, atoms, and molecules in the presence of ultrashort light pulses. Several examples are discussed illustrating how light pulses can trigger and control electronic, atomic, and molecular motions. In the first part of this work, I focus on the rotational motion of asymmetric molecules, which happens on picosecond and femtosecond time scales. Here, the aim is to align all three axes of the molecule as well as possible. To investigate theoretically alignment dynamics, I developed a program that can describe alignment motion ranging from the impulsive to the adiabatic regime. The asymmetric molecule SO{sub 2} is taken as an example to discuss strategies of optimizing 3D alignment without the presence of an external field (i.e., field-free alignment). Field-free alignment is particularly advantageous because subsequent experiments on the aligned molecule are not perturbed by the aligning light pulse. Wellaligned molecules in the gas phase are suitable for diffraction experiments. From the
International Nuclear Information System (INIS)
Pabst, Stefan Ulf
2013-04-01
The concept of atoms as the building blocks of matter has existed for over 3000 years. A revolution in the understanding and the description of atoms and molecules has occurred in the last century with the birth of quantum mechanics. After the electronic structure was understood, interest in studying the dynamics of electrons, atoms, and molecules increased. However, time-resolved investigations of these ultrafast processes were not possible until recently. The typical time scale of atomic and molecular processes is in the picosecond to attosecond realm. Tremendous technological progress in recent years makes it possible to generate light pulses on these time scales. With such ultrashort pulses, atomic and molecular dynamics can be triggered, watched, and controlled. Simultaneously, the need rises for theoretical models describing the underlying mechanisms. This doctoral thesis focuses on the development of theoretical models which can be used to study the dynamical behavior of electrons, atoms, and molecules in the presence of ultrashort light pulses. Several examples are discussed illustrating how light pulses can trigger and control electronic, atomic, and molecular motions. In the first part of this work, I focus on the rotational motion of asymmetric molecules, which happens on picosecond and femtosecond time scales. Here, the aim is to align all three axes of the molecule as well as possible. To investigate theoretically alignment dynamics, I developed a program that can describe alignment motion ranging from the impulsive to the adiabatic regime. The asymmetric molecule SO 2 is taken as an example to discuss strategies of optimizing 3D alignment without the presence of an external field (i.e., field-free alignment). Field-free alignment is particularly advantageous because subsequent experiments on the aligned molecule are not perturbed by the aligning light pulse. Wellaligned molecules in the gas phase are suitable for diffraction experiments. From the
DEFF Research Database (Denmark)
Chen, Gang; GOVINDAN, Kannan; Golias, Mihalis M.
2012-01-01
This study proposes a methodology to optimize truck arrival patterns to reduce emissions from idling truck engines at marine container terminals. A bi-objective model is developed minimizing both truck waiting times and truck arrival pattern change. The truck waiting time is estimated via...... a queueing network. Based on the waiting time, truck idling emissions are estimated. The proposed methodology is evaluated with a case study, where truck arrival rates vary over time. We propose a Genetic Algorithm based heuristic to solve the resulting problem. Result shows that, a small shift of truck...... arrivals can significantly reduce truck emissions, especially at the gate....
Efficient Redundancy Techniques in Cloud and Desktop Grid Systems using MAP/G/c-type Queues
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.
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.
Analysis of Single-Server Queue with Phase-Type Service and Energy Harvesting
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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.
An unreliable group arrival queue with k stages of service, retrial under variant vacation policy
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.
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....
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...
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...
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.
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.
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.
Chaotic queue-based genetic algorithm for design of a self-tuning fuzzy logic controller
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.
Directory of Open Access Journals (Sweden)
Irina IOSUB
2016-06-01
Full Text Available In the context of increasingly accelerated development of technology and particularly of the Internet, mass communication acquires new meanings. This article proposes a brief theoretical approach to the study of mass communication as it was treated in the specific literature of the 50s and 60s, when there was little talk about new technologies. However, many features identified since then still retain their topicality and for this reason it is interesting to note the evolution over time of the main communication models that were and some of them still are used for the study of mass communication. They are relevant to the context in which a complete study of mass communication is required, not only from the perspective of the present, but also from the period in which it was outlined. Thus, this article is divided into three main sections: the first part represents the meaning of communication in a general sense, so that the second part to represent the mass communication process and its characteristics, and the last part to represent the main models of communication in the order in which they have occurred, and especially aiming at new features that each of them brought.
Groenewegen, P.P.; Westert, G.P.
2004-01-01
The aim of this study was to review the research evidence for a decreasing time trend in medical practice variation and to contribute to our theoretical understanding of trends in medical practice variations. We searched Pubmed for articles reporting on time trends in medical practice variations.
On the correlation structure of a Lévy-driven queue
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
Queueing networks with string transitions of mixed vector additions and vector removals
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
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.
Optimal hysteretic control for a BMAP/SM/1/N queue with two operation modes
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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.
Analysis of Markov-modulated infinite-server queues in the central-limit regime
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
Analysis of Markov-modulated infinite-server queues in the central-limit regime
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
Analysis of Markov-modulated infinite-server queues in the central-limit regime
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
On first-come first-served versus random service discipline in multiclass closed queueing networks
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
A new, analysis-based, change of measure for tandem queues
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
A computational approach for fluid queues driven by truncated birth-death processes.
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
A queueing model of pilot decision making in a multi-task flight management situation
Walden, R. S.; Rouse, W. B.
1977-01-01
Allocation of decision making responsibility between pilot and computer is considered and a flight management task, designed for the study of pilot-computer interaction, is discussed. A queueing theory model of pilot decision making in this multi-task, control and monitoring situation is presented. An experimental investigation of pilot decision making and the resulting model parameters are discussed.
Research on elastic resource management for multi-queue under cloud computing environment
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.
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 ...
Active Methodologies in a Queueing Systems Course for Telecommunication Engineering Studies
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…
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.
The queueing perspective of asynchronous network coding in two-way relay network
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.
Multicast Services of QoS-Aware Active Queue Management over IP Multimedia Applications
Hwang, I.-Shyan; Hwang, Bor-Jiunn; Chang, Pen-Ming
2010-10-01
Recently, the multimedia services such as IPTV, video conference emerges to be the main traffic source. When UDP coexists with TCP, it induces not only congestion collapse but also unfairness problem. In this paper, a new Active Queue Management (AQM) algorithm, called Traffic Sensitive Active Queue Management (TSAQM), is proposed for providing multimedia services. The TSAQM comprise Dynamic Weight Allocate Scheme (DWAS) and Service Guarantee Scheme (SGS), the purpose of DWAS is to allocate resource with fairness and high end-user utility, and the purpose of SGS is to determine the satisfactory threshold (TH) and threshold region (TR). Several objectives of this proposed scheme include achieving high end-user utility for video service, considering the multicast as well as unicast proprieties to meet inter-class fairness and achieving the QoS requirement by adjusting the thresholds adaptively based on traffic situations.
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.
Impact of sensing errors on the queueing delay and transmit power in cognitive radio access
Hamza, Doha R.
2011-03-01
We study a multiple-access system with a primary user (PU) and a secondary user (SU) utilizing the same frequency band and communicating with a common receiver. Both users transmit with a fixed transmission rate by employing a channel inversion power control scheme. The SU transmits with a certain probability that depends on the sensing outcome, its queue length and whether it has a new packet arrival. We consider the case of erroneous sensing. The goal of the SU is to find the optimal transmission scheduling policy so as to minimize its queueing delay under constraints on its average transmit power and the maximum tolerable primary outage probability caused by miss-detection. The access probabilities are obtained efficiently using linear programming. © 2011 IEEE.
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.
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
An Active Queue Management for QoS Guarantee of the High Priority Service Class
Kim, Hyun Jong; Shim, Jae Chan; Kim, Hwa-Suk; Cho, Kee Seong; Choi, Seong Gon
In this paper, we propose the active queue management mechanism (Active-WRED) for guaranteeing the quality of the high priority service class (VoIP or IPTV) in the multi-class traffic service environment. In the congestion situation, this mechanism increases the drop probability of the low priority traffic and reduces the drop probability of the high priority traffic; therefore it can guarantee the quality of the high priority service class from the poor quality by the packet loss.
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
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.
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
Predictive functional control for active queue management in congested TCP/IP networks.
Bigdeli, N; Haeri, M
2009-01-01
Predictive functional control (PFC) as a new active queue management (AQM) method in dynamic TCP networks supporting explicit congestion notification (ECN) is proposed. The ability of the controller in handling system delay along with its simplicity and low computational load makes PFC a privileged AQM method in the high speed networks. Besides, considering the disturbance term (which represents model/process mismatches, external disturbances, and existing noise) in the control formulation adds some level of robustness into the PFC-AQM controller. This is an important and desired property in the control of dynamically-varying computer networks. In this paper, the controller is designed based on a small signal linearized fluid-flow model of the TCP/AQM networks. Then, closed-loop transfer function representation of the system is derived to analyze the robustness with respect to the network and controller parameters. The analytical as well as the packet-level ns-2 simulation results show the out-performance of the developed controller for both queue regulation and resource utilization. Fast response, low queue fluctuations (and consequently low delay jitter), high link utilization, good disturbance rejection, scalability, and low packet marking probability are other features of the developed method with respect to other well-known AQM methods such as RED, PI, and REM which are also simulated for comparison.
A spatiotemporal model for the LTE uplink: Spatially interacting tandem queues approach
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.
Polidori, G; Marreiro, A; Pron, H; Lestriez, P; Boyer, F C; Quinart, H; Tourbah, A; Taïar, R
2016-11-01
This article establishes the basics of a theoretical model for the constitutive law that describes the skin temperature and thermolysis heat losses undergone by a subject during a session of whole-body cryotherapy (WBC). This study focuses on the few minutes during which the human body is subjected to a thermal shock. The relationship between skin temperature and thermolysis heat losses during this period is still unknown and have not yet been studied in the context of the whole human body. The analytical approach here is based on the hypothesis that the skin thermal shock during a WBC session can be thermally modelled by the sum of both radiative and free convective heat transfer functions. The validation of this scientific approach and the derivation of temporal evolution thermal laws, both on skin temperature and dissipated thermal power during the thermal shock open many avenues of large scale studies with the aim of proposing individualized cryotherapy protocols as well as protocols intended for target populations. Furthermore, this study shows quantitatively the substantial imbalance between human metabolism and thermolysis during WBC, the explanation of which remains an open question. Copyright © 2016 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Zhu, Y.T.; Lowe, T.C.; Asaro, R.J.
1997-01-01
The rule of additivity was first proposed by Scheil and Steinberg for predicting the incubation time for nucleation of solid phases during continuous-cooling phase transformations, and has since been widely used for both the nucleation incubation and the entire process of phase transformation. While having been successfully used to calculate the transformed volume fraction during continuous cooling in many steel alloy systems, there is experimental evidence that shows rule of additivity to be invalid for describing the incubation time for nucleation. Attempts to prove the validity of the rule of additivity for the incubation time have not met with much success, and much confusion still exists about its applicability to the incubation time. This article investigates the additivity of the consumption of the incubation time for nucleation during continuous cooling through an analysis based upon classical nucleation theory. It is rigorously demonstrated that the rule of additivity is invalid for the incubation time for nucleation. However, in practice, the relative error caused by using the rule of additivity could be very small in many cases due to the resolution limit of current experimental techniques. The present theory provides an explanation for the failure of the rule of additivity in predicting the incubation time for nucleation during continuous cooling. copyright 1997 American Institute of Physics
National Research Council Canada - National Science Library
Gates, Ordway
1951-01-01
A method is presented for determining the control gearing and time lag necessary for a specified damping of the motions of an aircraft equipped with an autopilot having constant-time-lag characteristics...
Directory of Open Access Journals (Sweden)
Borkowski Andrzej
2015-12-01
Full Text Available The paper presents a summary of research activities concerning theoretical geodesy performed in Poland in the period of 2011-2014. It contains the results of research on new methods of the parameter estimation, a study on robustness properties of the M-estimation, control network and deformation analysis, and geodetic time series analysis. The main achievements in the geodetic parameter estimation involve a new model of the M-estimation with probabilistic models of geodetic observations, a new Shift-Msplit estimation, which allows to estimate a vector of parameter differences and the Shift-Msplit(+ that is a generalisation of Shift-Msplit estimation if the design matrix A of a functional model has not a full column rank. The new algorithms of the coordinates conversion between the Cartesian and geodetic coordinates, both on the rotational and triaxial ellipsoid can be mentioned as a highlights of the research of the last four years. New parameter estimation models developed have been adopted and successfully applied to the control network and deformation analysis.
Makabe, Toshiaki
2018-03-01
A time-varying low-temperature plasma sustained by electrical powers with various kinds of fRequencies has played a key role in the historical development of new technologies, such as gas lasers, ozonizers, micro display panels, dry processing of materials, medical care, and so on, since World War II. Electrons in a time-modulated low-temperature plasma have a proper velocity spectrum, i.e. velocity distribution dependent on the microscopic quantum characteristics of the feed gas molecule and on the external field strength and the frequency. In order to solve and evaluate the time-varying velocity distribution, we have mostly two types of theoretical methods based on the classical and linear Boltzmann equations, namely, the expansion method using the orthogonal function and the procedure of non-expansional temporal evolution. Both methods have been developed discontinuously and progressively in synchronization with those technological developments. In this review, we will explore the historical development of the theoretical procedure to evaluate the electron velocity distribution in a time-varying low-temperature plasma over the past 70 years.
Theoretical Time Dependent Thermal Neutron Spectra and Reaction Rates in H{sub 2}O and D{sub 2}O
Energy Technology Data Exchange (ETDEWEB)
Purohit, S.N.
1966-04-15
The early theoretical and experimental time dependent neutron thermalization studies were limited to the study of the transient spectrum in the diffusion period. The recent experimental measurements of the time dependent thermal neutron spectra and reaction rates, for a number of moderators, have generated considerable interest in the study of the time dependent Boltzmann equation. In this paper we present detailed results for the time dependent spectra and the reaction rates for resonance detectors using several scattering models of H{sub 2}O and D{sub 2}O. This study has been undertaken in order to interpret the integral time dependent neutron thermalization experiments in liquid moderators which have been performed at the AB Atomenergi. The proton gas and the deuteron gas models are inadequate to explain the measured reaction rates in H{sub 2}O and D{sub 2}O. The bound models of Nelkin for H{sub 2}O and of Butler for D{sub 2}O give much better agreement with the experimental results than the gas models. Nevertheless, some disagreement between theoretical and experimental results still persists. This study also indicates that the bound model of Butler and the effective mass 3. 6 gas model of Brown and St. John give almost identical reaction rates. It is also surprising to note that the calculated reaction rate for Cd for the Butler model appears to be in better agreement with the experimental results of D{sub 2}O than of the Nelkin model with H{sub 2}O experiments. The present reaction rate studies are sensitive enough so as to distinguish between the gas model and the bound model of a moderator. However, to investigate the details of a scattering law (such as the effect of the hindered rotations in H{sub 2}O and D{sub 2}O and the weights of different dynamical modes) with the help of these studies would require further theoretical as well as experimental investigations. Theoretical results can be further improved by improving the source for thermal neutrons, the
Tolis, Athanasios; Rentizelas, Athanasios; Aravossis, Konstantin; Tatsiopoulos, Ilias
2010-11-01
Waste management has become a great social concern for modern societies. Landfill emissions have been identified among the major contributors of global warming and climate changes with significant impact in national economies. The energy industry constitutes an additional greenhouse gas emitter, while at the same time it is characterized by significant costs and uncertain fuel prices. The above implications have triggered different policies and measures worldwide to address the management of municipal solid wastes on the one hand and the impacts from energy production on the other. Emerging methods of energy recovery from waste may address both concerns simultaneously. In this work a comparative study of co-generation investments based on municipal solid waste is presented, focusing on the evolution of their economical performance over time. A real-options algorithm has been adopted investigating different options of energy recovery from waste: incineration, gasification and landfill biogas exploitation. The financial contributors are identified and the impact of greenhouse gas trading is analysed in terms of financial yields, considering landfilling as the baseline scenario. The results indicate an advantage of combined heat and power over solely electricity production. Gasification, has failed in some European installations. Incineration on the other hand, proves to be more attractive than the competing alternatives, mainly due to its higher power production efficiency, lower investment costs and lower emission rates. Although these characteristics may not drastically change over time, either immediate or irreversible investment decisions might be reconsidered under the current selling prices of heat, power and CO(2) allowances.
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.
Yamazaki, M.; Nakayama, S.; Zhu, C. Y.; Takahashi, M.
2017-11-01
We report on theoretical progress in time-resolved (e, 2e) electron momentum spectroscopy of photodissociation dynamics of the deuterated acetone molecule at 195 nm. We have examined the predicted minimum energy reaction path to investigate whether associated (e, 2e) calculations meet the experimental results. A noticeable difference between the experiment and calculations has been found at around binding energy of 10 eV, suggesting that the observed difference may originate, at least partly, in ever-unconsidered non-minimum energy paths.
Pereverzev, Andrey; Sewell, Tommy
2018-03-01
Lattice heat-current time correlation functions for insulators and semiconductors obtained using molecular dynamics (MD) simulations exhibit features of both pure exponential decay and oscillatory-exponential decay. For some materials the oscillatory terms contribute significantly to the lattice heat conductivity calculated from the correlation functions. However, the origin of the oscillatory terms is not well understood, and their contribution to the heat conductivity is accounted for by fitting them to empirical functions. Here, a translationally invariant expression for the heat current in terms of creation and annihilation operators is derived. By using this full phonon-picture definition of the heat current and applying the relaxation-time approximation we explain, at least in part, the origin of the oscillatory terms in the lattice heat-current correlation function. We discuss the relationship between the crystal Hamiltonian and the magnitude of the oscillatory terms. A solvable one-dimensional model is used to illustrate the potential importance of terms that are omitted in the commonly used phonon-picture expression for the heat current. While the derivations are fully quantum mechanical, classical-limit expressions are provided that enable direct contact with classical quantities obtainable from MD.
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.
Queueing Network Models for Parallel Processing of Task Systems: an Operational Approach
Mak, Victor W. K.
1986-01-01
Computer performance modeling of possibly complex computations running on highly concurrent systems is considered. Earlier works in this area either dealt with a very simple program structure or resulted in methods with exponential complexity. An efficient procedure is developed to compute the performance measures for series-parallel-reducible task systems using queueing network models. The procedure is based on the concept of hierarchical decomposition and a new operational approach. Numerical results for three test cases are presented and compared to those of simulations.
Analysis of the Optimal Resource Allocation for a Tandem Queueing System
Zaiming, Liu; Gang, Chen; Jinbiao, Wu
2015-01-01
We study a controllable two-station tandem queueing system, where customers (jobs) must first be processed at upstream station and then the downstream station. A manager dynamically allocates the service resource to each station to adjust the service rate, leading to a tradeoff between the holding cost and resource cost. The goal of the manager is to find the optimal policy to minimize the long-run average costs. The problem is constructed as a Markov decision process (MDP). In this paper, we...
Performance Analysis Of Active Queue Management AQM In VOIP Using Different Voice Encoder Scheme
Samir Eid Mohammed; Mohamed H. M. Nerma
2015-01-01
Abstract Voice over Internet Protocol VoIP is a rapidly growing technology that enables transport of voice over data networks such as Ethernet Wide area networks WANs due to this important different codec scheme is developed to meet the QoS requirements. This thesis presents a comprehensive study about the impact of active queue management AQM on Voice over Internet Protocol VoIP quality of service using different codec scheme such as G711 G723 G729 and GSM using simulations tools. The evalua...
Queued Service Observing (QSO) at CFHT II. Queue Preparation and Observation Tools
Vermeulen, T.; Savalle, R.; Martin, P.; Shapiro, J.
In order to maximize the scientific productivity of the CFH12K mosaic wide-field imager, a Queued Service Observing (QSO) mode of operations was implemented at CFHT . To support this new operational model, a two-tiered system consisting of a Swing-based Java client and a relational database was developed. The various software components were designed to handle selection, scheduling, execution, and validation of programs submitted by the investigators through the CFHT Phase 2 Tool (PH2). This paper will discuss the technical architecture, the reasons behind our choice of technology, and our experience implementing this system during the first two semesters of Queue observing.
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.
Energy Technology Data Exchange (ETDEWEB)
Freericks, J. K.; Krishnamurthy, H. R.; Sentef, M. A.; Devereaux, T. P.
2015-10-01
Nonequilibrium calculations in the presence of an electric field are usually performed in a gauge, and need to be transformed to reveal the gauge-invariant observables. In this work, we discuss the issue of gauge invariance in the context of time-resolved angle-resolved pump/probe photoemission. If the probe is applied while the pump is still on, one must ensure that the calculations of the observed photocurrent are gauge invariant. We also discuss the requirement of the photoemission signal to be positive and the relationship of this constraint to gauge invariance. We end by discussing some technical details related to the perturbative derivation of the photoemission spectra, which involve processes where the pump pulse photoexcites electrons due to nonequilibrium effects.
Utter, Garth H
2013-12-01
Clinicians place chest tubes approximately 1 million times each year in the United States, but little information is available to guide their management. Specifically, use of the rate of pleural fluid drainage as a criterion for tube removal is not standardized. Absent such tubes, pleural fluid drains primarily through parietal pleural lymphatics at rates approaching 500 mL of fluid per day or more for each hemithorax. Early removal of tubes does not appear to be harmful. A noninferiority randomized trial currently in progress comparing removal without considering the drainage rate to a conservative threshold (2 mL/kg body weight in 24 hours) may better inform tube management. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.
Trapman, Pieter; Bootsma, Martinus Christoffel Jozef
2009-05-01
In this paper we establish a relation between the spread of infectious diseases and the dynamics of so called M/G/1 queues with processor sharing. The relation between the spread of epidemics and branching processes, which is well known in epidemiology, and the relation between M/G/1 queues and birth death processes, which is well known in queueing theory, will be combined to provide a framework in which results from queueing theory can be used in epidemiology and vice versa. In particular, we consider the number of infectious individuals in a standard SIR epidemic model at the moment of the first detection of the epidemic, where infectious individuals are detected at a constant per capita rate. We use a result from the literature on queueing processes to show that this number of infectious individuals is geometrically distributed.
Nagar, Swati; Jones, Jeffrey P.
2014-01-01
Inhibition of cytochromes P450 by time-dependent inhibitors (TDI) is a major cause of clinical drug-drug interactions. It is often difficult to predict in vivo drug interactions based on in vitro TDI data. In part 1 of these manuscripts, we describe a numerical method that can directly estimate TDI parameters for a number of kinetic schemes. Datasets were simulated for Michaelis-Menten (MM) and several atypical kinetic schemes. Ordinary differential equations were solved directly to parameterize kinetic constants. For MM kinetics, much better estimates of KI can be obtained with the numerical method, and even IC50 shift data can provide meaningful estimates of TDI kinetic parameters. The standard replot method can be modified to fit non-MM data, but normal experimental error precludes this approach. Non-MM kinetic schemes can be easily incorporated into the numerical method, and the numerical method consistently predicts the correct model at errors of 10% or less. Quasi-irreversible inactivation and partial inactivation can be modeled easily with the numerical method. The utility of the numerical method for the analyses of experimental TDI data is provided in our companion manuscript in this issue of Drug Metabolism and Disposition (Korzekwa et al., 2014b). PMID:24939654
A queueing theory based model for business continuity in hospitals.
Miniati, R; Cecconi, G; Dori, F; Frosini, F; Iadanza, E; Biffi Gentili, G; Niccolini, F; Gusinu, R
2013-01-01
Clinical activities can be seen as results of precise and defined events' succession where every single phase is characterized by a waiting time which includes working duration and possible delay. Technology makes part of this process. For a proper business continuity management, planning the minimum number of devices according to the working load only is not enough. A risk analysis on the whole process should be carried out in order to define which interventions and extra purchase have to be made. Markov models and reliability engineering approaches can be used for evaluating the possible interventions and to protect the whole system from technology failures. The following paper reports a case study on the application of the proposed integrated model, including risk analysis approach and queuing theory model, for defining the proper number of device which are essential to guarantee medical activity and comply the business continuity management requirements in hospitals.
Reproductive queue without overt conflict in the primitively eusocial wasp Ropalidia marginata.
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.
QoS-Aware Active Queue Management for Multimedia Services over the Internet
Directory of Open Access Journals (Sweden)
Hwang I-Shyan
2011-01-01
Full Text Available Recently, with multimedia services such as IPTV, video conferencing has emerged as a main traffic source. When UDP coexists with TCP, it induces not only congestion collapse but also an unfairness problem. In this paper, a new Active Queue Management algorithm, called Traffic Sensitive Active Queue Management (TSAQM, is proposed for providing multimedia services in routers. The TSAQM is comprised of Dynamic Weight Allocate Scheme (DWAS and Service Guarantee Scheme (SGS. The purpose of DWAS is to fairly allocate resources with high end-user utility, and the SGS is to determine the satisfactory threshold (TH and threshold region (TR. Besides, a multiqueue design for different priority traffic, and threshold TH and threshold region TR is proposed to achieve the different QoS requirements. Several objectives of this proposed scheme include achieving high end user utility for video services, considering the multicast as well as unicast proprieties to meet interclass fairness, and achieving the QoS requirement by adaptively adjusting the thresholds based on the traffic situations. Performance comparisons with the GRED-I are in terms of packet dropping rate and throughput to highlight the better behavior of the proposed schemes due to taking into account the fairness and different weights for video layers.
Survival of the Fittest: An Active Queue Management Technique for Noisy Packet Flows
Directory of Open Access Journals (Sweden)
Shirish S. Karande
2007-01-01
Full Text Available We present a novel active queue management (AQM technique to demonstrate the efficacy of practically harnessing the predictive utility of SSR indications for improved video communication. We consider a network within which corrupted packets are relayed over multiple hops, but a certain percentage of packets needs to be dropped at an intermediate node due to congestion. We propose an AQM technique, survival of the fittest (SOTF, to be employed at the relay node, within which we use packet state information, available from SSR indications and checksums, to drop packets with the highest corruption levels. On the basis of actual 802.11b measurements we show that such a side information (SI aware processing within the network can provide significant performance benefits over an SI-unaware scheme, random queue management (RQM, which is forced to randomly discard packets. With trace-based simulations, we show the utility of the proposed AQM technique in improving the error recovery performance of cross-layer FEC schemes. Finally, with the help of H.264-based video simulations these improvements are shown to translate into a significant improvement in video quality.
Handover Management for VoWLAN Based on Estimation of AP Queue Length and Frame Retries
Niswar, Muhammad; Kashihara, Shigeru; Tsukamoto, Kazuya; Kadobayashi, Youki; Yamaguchi, Suguru
Switching a communication path from one Access Point (AP) to another in inter-domain WLANs is a critical challenge for delay-sensitive applications such as Voice over IP (VoIP) because communication quality during handover (HO) is more likely to be deteriorated. To maintain VoIP quality during HO, we need to solve many problems. In particular, in bi-directional communication such as VoIP, an AP becomes a bottleneck with the increase of VoIP calls. As a result, packets queued in the AP buffer may experience a large queuing delay or packet losses due to increase in queue length or buffer overflow, thereby causing the degradation of VoIP quality for the Mobile Nodes (MNs) side. To avoid this degradation, MNs need to appropriately and autonomously execute HO in response to the change in wireless network condition, i.e., the deterioration of wireless link quality and the congestion state at the AP. In this paper, we propose an HO decision strategy considering frame retries, AP queue length, and transmission rate at an MN for maintaining VoIP quality during HO. Through simulation experiments, we then show that our proposed method can maintain VoIP quality during HO by properly detecting the wireless network condition.
Directory of Open Access Journals (Sweden)
Wenqing Wu
2014-05-01
Full Text Available This paper studies an M/G/1 repairable queueing system with multiple vacations and N-policy, in which the service station is subject to occasional random breakdowns. When the service station breaks down, it is repaired by a repair facility. Moreover, the repair facility may fail during the repair period of the service station. The failed repair facility resumes repair after completion of its replacement. Under these assumptions, applying a simple method, the probability that the service station is broken, the rate of occurrence of breakdowns of the service station, the probability that the repair facility is being replaced and the rate of occurrence of failures of the repair facility along with other performance measures are obtained. Following the construction of the long-run expected cost function per unit time, the direct search method is implemented for determining the optimum threshold N* that minimises the cost function.
A note on many-server queueing systems with ordered entry, with an application to conveyor theory
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
International Nuclear Information System (INIS)
Anon.
1975-01-01
Work in theoretical chemistry was organized under the following topics: scattering theory and dynamics (elastic scattering of the rare gas hydrides, inelastic scattering in Li + H 2 , statistical theory for bimolecular collisions, model study of dissociative scattering, comparative study of elastic scattering computational methods), studies of atmospheric diatomic and triatomic species, structure and spectra of diatomic molecules, the evaluation of van der Waals forces, potential energy surfaces and structure and dynamics, calculation of molecular polarizabilities, and development of theoretical techniques and computing systems. Spectroscopic parameters are tabulated for NO 2 , N 2 O, H 2 O + , VH, and NH. Self-consistent-field wave functions were computed for He 2 in two-center and three-center bases. Rare gas hydride intermolecular potentials are shown. (9 figures, 14 tables) (U.S.)
Hartzell, S.; Guatteri, Mariagiovanna; Mai, P.M.; Liu, P.-C.; Fisk, M. R.
2005-01-01
In the evolution of methods for calculating synthetic time histories of ground motion for postulated earthquakes, kinematic source models have dominated to date because of their ease of application. Dynamic models, however, which incorporate a physical relationship between important faulting parameters of stress drop, slip, rupture velocity, and rise time, are becoming more accessible. This article compares a class of kinematic models based on the summation of a fractal distribution of subevent sizes with a dynamic model based on the slip-weakening friction law. Kinematic modeling is done for the frequency band 0.2 to 10.0. Hz, dynamic models are calculated from 0.2 to 2.0. Hz. The strong motion data set for the 1994 Northridge earthquake is used to evaluate and compare the synthetic time histories. Source models are propagated to the far field by convolution with 1D and 3D theoretical Green’s functions. In addition, the kinematic model is used to evaluate the importance of propagation path effects: velocity structure, scattering, and nonlinearity. At present, the kinematic model gives a better broadband fit to the Northridge ground motion than the simple slip-weakening dynamic model. In general, the dynamic model overpredicts rise times and produces insufficient shorter-period energy. Within the context of the slip-weakening model, the Northridge ground motion requires a short slip-weakening distance, on the order of 0.15 m or less. A more complex dynamic model including rate weakening or one that allows shorter rise times near the hypocenter may fit the data better.
WQM: An Aggregation-aware Queue Management Scheme for IEEE 802.11n based Networks
Showail, Ahmad
2014-08-17
Choosing the right buffer size in Wi-Fi networks is challenging due to the dynamic nature of the wireless environment. Over buffering or \\'bufferbloat\\' may produce unacceptable end-to-end delays, while static small buffers may limit the performance gains that can be achieved with various 802.11n enhancements, such as frame aggregation. We propose WQM, a queue management scheme customized for wireless networks. WQM adapts the buffer size based on measured link characteristics and network load. Furthermore, it accounts for aggregate length when deciding about the optimal buffer size. We implement WQM on Linux and evaluate it on a wireless testbed. WQM reduces the end-to-end delay by up to 8x compared to Linux default buffer size, and 2x compared to CoDel, the state-of-the-art bufferbloat solution, while achieving comparable network goodput. Further, WQM improves fairness as it limits the ability of a single flow to saturate the buffer.
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.
Analysis of the Optimal Resource Allocation for a Tandem Queueing System
Directory of Open Access Journals (Sweden)
Zaiming Liu
2017-01-01
Full Text Available We study a controllable two-station tandem queueing system, where customers (jobs must first be processed at upstream station and then the downstream station. A manager dynamically allocates the service resource to each station to adjust the service rate, leading to a tradeoff between the holding cost and resource cost. The goal of the manager is to find the optimal policy to minimize the long-run average costs. The problem is constructed as a Markov decision process (MDP. In this paper, we consider the model in which the resource cost and service rate functions are more general than linear. We derive the monotonicity of the optimal allocation policy by the quasiconvexity properties of the value function. Furthermore, we obtain the relationship between the two stations’ optimal policy and conditions under which the optimal policy is unique and has the bang-bang control property. Finally, we provide some numerical experiments to illustrate these results.
Joos, Georg
1986-01-01
Among the finest, most comprehensive treatments of theoretical physics ever written, this classic volume comprises a superb introduction to the main branches of the discipline and offers solid grounding for further research in a variety of fields. Students will find no better one-volume coverage of so many essential topics; moreover, since its first publication, the book has been substantially revised and updated with additional material on Bessel functions, spherical harmonics, superconductivity, elastomers, and other subjects.The first four chapters review mathematical topics needed by theo
Directory of Open Access Journals (Sweden)
Yasser Abduallah
2017-01-01
Full Text Available Gene regulation is a series of processes that control gene expression and its extent. The connections among genes and their regulatory molecules, usually transcription factors, and a descriptive model of such connections are known as gene regulatory networks (GRNs. Elucidating GRNs is crucial to understand the inner workings of the cell and the complexity of gene interactions. To date, numerous algorithms have been developed to infer gene regulatory networks. However, as the number of identified genes increases and the complexity of their interactions is uncovered, networks and their regulatory mechanisms become cumbersome to test. Furthermore, prodding through experimental results requires an enormous amount of computation, resulting in slow data processing. Therefore, new approaches are needed to expeditiously analyze copious amounts of experimental data resulting from cellular GRNs. To meet this need, cloud computing is promising as reported in the literature. Here, we propose new MapReduce algorithms for inferring gene regulatory networks on a Hadoop cluster in a cloud environment. These algorithms employ an information-theoretic approach to infer GRNs using time-series microarray data. Experimental results show that our MapReduce program is much faster than an existing tool while achieving slightly better prediction accuracy than the existing tool.
Applying a foil queue micro-electrode in micro-EDM to fabricate a 3D micro-structure
Xu, Bin; Guo, Kang; Wu, Xiao-yu; Lei, Jian-guo; Liang, Xiong; Guo, Deng-ji; Ma, Jiang; Cheng, Rong
2018-05-01
Applying a 3D micro-electrode in a micro electrical discharge machining (micro-EDM) can fabricate a 3D micro-structure with an up and down reciprocating method. However, this processing method has some shortcomings, such as a low success rate and a complex process for fabrication of 3D micro-electrodes. By focusing on these shortcomings, this paper proposed a novel 3D micro-EDM process based on the foil queue micro-electrode. Firstly, a 3D micro-electrode was discretized into several foil micro-electrodes and these foil micro-electrodes constituted a foil queue micro-electrode. Then, based on the planned process path, foil micro-electrodes were applied in micro-EDM sequentially and the micro-EDM results of each foil micro-electrode were able to superimpose the 3D micro-structure. However, the step effect will occur on the 3D micro-structure surface, which has an adverse effect on the 3D micro-structure. To tackle this problem, this paper proposes to reduce this adverse effect by rounded corner wear at the end of the foil micro-electrode and studies the impact of machining parameters on rounded corner wear and the step effect on the micro-structure surface. Finally, using a wire cutting voltage of 80 V, a current of 0.5 A and a pulse width modulation ratio of 1:4, the foil queue micro-electrode was fabricated by wire electrical discharge machining. Also, using a pulse width of 100 ns, a pulse interval of 200 ns, a voltage of 100 V and workpiece material of 304# stainless steel, the foil queue micro-electrode was applied in micro-EDM for processing of a 3D micro-structure with hemispherical features, which verified the feasibility of this process.
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.
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
Skripnikov, L. V.; Titov, A. V.
2016-08-01
An experiment towards the search for the interaction of the Schiff moment (S) of the 207Pb nuclei with electrons in PbTiO3 crystal which violates the time reversal (T) and space parity (P) symmetries was proposed by Mukhamedjanov and Sushkov [Phys. Rev. A 72, 034501 (2005)]. The interpretation of the experiment in terms of the Schiff moment requires knowledge of an electronic density gradient parameter (usually designated as X) on the Pb nucleus in the crystal, which is determined by the electronic structure of the crystal. Here we propose a theoretical approach to calculate the properties in solids which are directly sensitive to the changes of valence electron densities in atomic cores but not in the valence spatial regions (Mössbauer parameters, hyperfine structure (HFS) constants, parameters of T,P-odd Hamiltonians, etc. [L. V. Skripnikov and A. V. Titov, Phys. Rev. A 91, 042504 (2015)]). It involves constructing the crystalline orbitals via the linear combination of atomic orbitals and employs a two-step concept of calculating such properties that was earlier proposed by us for the case of heavy-atom molecules. The application of the method to the PbTiO3 crystal results in the energy shift, Δ ɛ = 0 . 82 × 1 0 6 /S ( 207 Pb ) e aB 3 eV , due to the T,P-odd interactions. The value is compared to the corresponding parameter in diatomic molecules (TlF, RaO, PbO), which have been proposed and used in the past decades in the search for the nuclear Schiff moment. We also present the calculation of the electric field gradient at the Pb nucleus in PbTiO3 for the comparison with other solid-state electronic structure approaches.
Skripnikov, L V; Titov, A V
2016-08-07
An experiment towards the search for the interaction of the Schiff moment (S) of the (207)Pb nuclei with electrons in PbTiO3 crystal which violates the time reversal (T) and space parity (P) symmetries was proposed by Mukhamedjanov and Sushkov [Phys. Rev. A 72, 034501 (2005)]. The interpretation of the experiment in terms of the Schiff moment requires knowledge of an electronic density gradient parameter (usually designated as X) on the Pb nucleus in the crystal, which is determined by the electronic structure of the crystal. Here we propose a theoretical approach to calculate the properties in solids which are directly sensitive to the changes of valence electron densities in atomic cores but not in the valence spatial regions (Mössbauer parameters, hyperfine structure (HFS) constants, parameters of T,P-odd Hamiltonians, etc. [L. V. Skripnikov and A. V. Titov, Phys. Rev. A 91, 042504 (2015)]). It involves constructing the crystalline orbitals via the linear combination of atomic orbitals and employs a two-step concept of calculating such properties that was earlier proposed by us for the case of heavy-atom molecules. The application of the method to the PbTiO3 crystal results in the energy shift, Δε=0.82×10(6)S((207)Pb)eaB (3)eV, due to the T,P-odd interactions. The value is compared to the corresponding parameter in diatomic molecules (TlF, RaO, PbO), which have been proposed and used in the past decades in the search for the nuclear Schiff moment. We also present the calculation of the electric field gradient at the Pb nucleus in PbTiO3 for the comparison with other solid-state electronic structure approaches.
Theoretical Mechanics Theoretical Physics 1
Dreizler, Reiner M
2011-01-01
After an introduction to basic concepts of mechanics more advanced topics build the major part of this book. Interspersed is a discussion of selected problems of motion. This is followed by a concise treatment of the Lagrangian and the Hamiltonian formulation of mechanics, as well as a brief excursion on chaotic motion. The last chapter deals with applications of the Lagrangian formulation to specific systems (coupled oscillators, rotating coordinate systems, rigid bodies). The level of this textbook is advanced undergraduate. The authors combine teaching experience of more than 40 years in all fields of Theoretical Physics and related mathematical disciplines and thorough knowledge in creating advanced eLearning content. The text is accompanied by an extensive collection of online material, in which the possibilities of the electronic medium are fully exploited, e.g. in the form of applets, 2D- and 3D-animations. - A collection of 74 problems with detailed step-by-step guidance towards the solutions. - A col...
Performance Analysis Of Active Queue Management AQM In VOIP Using Different Voice Encoder Scheme
Directory of Open Access Journals (Sweden)
Samir Eid Mohammed
2015-08-01
Full Text Available Abstract Voice over Internet Protocol VoIP is a rapidly growing technology that enables transport of voice over data networks such as Ethernet Wide area networks WANs due to this important different codec scheme is developed to meet the QoS requirements. This thesis presents a comprehensive study about the impact of active queue management AQM on Voice over Internet Protocol VoIP quality of service using different codec scheme such as G711 G723 G729 and GSM using simulations tools. The evaluation is done using the OPNET Modeler which provides a convenient and easy-to-use platform for simulating large scale networks and this also give a power to go through different levels of designing a network even with the ability to program the mechanism you want which is used here to implement two types of AQM mechanism which is not included by default in the OPNET and these two mechanisms are ARED and GRED. The performance metrics used in the study are jitter throughput and delay. The study shows that G.711 and G729 codecs in a simulation gives a significant result for the performance of VoIP that codec G711 and G.729A has acceptable throughput and less deviation of received to transmit packet as compared to GSM and G.723 also average delay like end to end delay and Voice jitter is lesser in codec G711 and G.729 as compared to the other two referenced codecs.
Three-dimensional flow structure measurements behind a queue of studied model vehicles
International Nuclear Information System (INIS)
Huang, J.F.; Chan, T.L.; Zhou, Y.
2009-01-01
The three-dimensional flow structures of a queue of studied model vehicles (i.e., one-, two- and three-vehicle cases) were investigated comprehensively in a closed-circuit wind tunnel using particle image velocimetry (PIV) for the typical urban vehicle speeds (i.e., 10, 30 and 50 km/h). In this three-dimensional vehicle wake, a pair of longitudinal vortices is characterized by counter-rotating and moving downstream at relatively low velocity than their surrounding flow. The flow structures of multiple studied model vehicles are dominated by the wake generated from the last studied model vehicle but the preceding studied model vehicle(s) also has/have some minor effects. Cross-sectional turbulence distribution is non-uniform in the far-wake region for all studied cases. The lowest turbulence occurs at the center part of the vehicle wake while high turbulence occurs at its two sides. As such, it may lead to considerable underestimation in turbulence magnitude if the measurement is only taken along the centerline of the vehicle wake.
DEFF Research Database (Denmark)
Bruus, Henrik
introducing microfluidics, the governing equations for mass, momentum and energy, and some basic flow solutions, the following 14 chapters treat hydraulic resistance/compliance, diffusion/dispersion, time-dependent flow, capillarity, electro- and magneto-hydrodynamics, thermal transport, two-phase flow......, complex flow patterns and acousto-fluidics, as well as the new fields of opto- and nano-fluidics. Throughout the book simple models with analytical solutions are presented to provide the student with a thorough physical understanding of order of magnitudes and various selected microfluidic phenomena...
Van Speybroeck, V.; Hemelsoet, K.L.J.; De Wispelaere, K.; Qian, Q.; Van der Mynsbrugge, J.; De Sterck, B.; Weckhuysen, B.M.; Waroquier, M.
2013-01-01
The formation and nature of active sites for methanol conversion over solid acid catalyst materials are studied by using a unique combined spectroscopic and theoretical approach. A working catalyst for the methanol-to-olefin conversion has a hybrid organic–inorganic nature in which a cocatalytic
MARKETING MIX THEORETICAL ASPECTS
Margarita Išoraitė
2016-01-01
Aim of article is to analyze marketing mix theoretical aspects. The article discusses that marketing mix is one of the main objectives of the marketing mix elements for setting objectives and marketing budget measures. The importance of each element depends not only on the company and its activities, but also on the competition and time. All marketing elements are interrelated and should be seen in the whole of their actions. Some items may have greater importance than others; it depends main...
Building a High Performance Metadata Broker using Clojure, NoSQL and Message Queues
Truslove, I.; Reed, S.
2013-12-01
In practice, Earth and Space Science Informatics often relies on getting more done with less: fewer hardware resources, less IT staff, fewer lines of code. As a capacity-building exercise focused on rapid development of high-performance geoinformatics software, the National Snow and Ice Data Center (NSIDC) built a prototype metadata brokering system using a new JVM language, modern database engines and virtualized or cloud computing resources. The metadata brokering system was developed with the overarching goals of (i) demonstrating a technically viable product with as little development effort as possible, (ii) using very new yet very popular tools and technologies in order to get the most value from the least legacy-encumbered code bases, and (iii) being a high-performance system by using scalable subcomponents, and implementation patterns typically used in web architectures. We implemented the system using the Clojure programming language (an interactive, dynamic, Lisp-like JVM language), Redis (a fast in-memory key-value store) as both the data store for original XML metadata content and as the provider for the message queueing service, and ElasticSearch for its search and indexing capabilities to generate search results. On evaluating the results of the prototyping process, we believe that the technical choices did in fact allow us to do more for less, due to the expressive nature of the Clojure programming language and its easy interoperability with Java libraries, and the successful reuse or re-application of high performance products or designs. This presentation will describe the architecture of the metadata brokering system, cover the tools and techniques used, and describe lessons learned, conclusions, and potential next steps.
Directory of Open Access Journals (Sweden)
Sarow Saeedi
2015-04-01
Full Text Available This paper considers the capacity determination in a closed-loop supply chain network when a queueing system is established in the reverse flow. Since the queueing system imposes costs on the model, the decision maker faces the challenge of determining the capacity of facilities in such a way that a compromise between the queueing costs and the fixed costs of opening new facilities could be obtained. We develop a De Novo programming approach to determine the capacity of recovery facilities in the reverse flow. To this aim, a mixed integer nonlinear programming (MINLP model is integrated with the De Novo programming and the robust counterpart of this model is proposed to cope with the uncertainty of the parameters. To solve the model, an interactive fuzzy programming approach is combined with the hard worst case robust programming. Numerical results show the performance of the developed model in determining the capacity of facilities.
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....
Theoretical developments in SUSY
Energy Technology Data Exchange (ETDEWEB)
Shifman, M. [University of Minnesota, William I. Fine Theoretical Physics Institute, Minneapolis, MN (United States)
2009-01-15
I am proud that I was personally acquainted with Julius Wess. We first met in 1999 when I was working on the Yuri Golfand Memorial Volume (The Many Faces of the Superworld, World Scientific, Singapore, 2000). I invited him to contribute, and he accepted this invitation with enthusiasm. After that, we met many times, mostly at various conferences in Germany and elsewhere. I was lucky to discuss with Julius questions of theoretical physics, and hear his recollections on how supersymmetry was born. In physics Julius was a visionary, who paved the way to generations of followers. In everyday life he was a kind and modest person, always ready to extend a helping hand to people who were in need of his help. I remember him telling me how concerned he was about the fate of theoretical physicists in Eastern Europe after the demise of communism. His ties with Israeli physicists bore a special character. I am honored by the opportunity to contribute an article to the Julius Wess Memorial Volume. I review theoretical developments of the recent years in non-perturbative supersymmetry. (orig.)
Theoretical Developments in SUSY
Shifman, M.
2009-01-01
I am proud that I was personally acquainted with Julius Wess. We first met in 1999 when I was working on the Yuri Golfand Memorial Volume (The Many Faces of the Superworld, World Scientific, Singapore, 2000). I invited him to contribute, and he accepted this invitation with enthusiasm. After that, we met many times, mostly at various conferences in Germany and elsewhere. I was lucky to discuss with Julius questions of theoretical physics, and hear his recollections on how supersymmetry was born. In physics Julius was a visionary, who paved the way to generations of followers. In everyday life he was a kind and modest person, always ready to extend a helping hand to people who were in need of his help. I remember him telling me how concerned he was about the fate of theoretical physicists in Eastern Europe after the demise of communism. His ties with Israeli physicists bore a special character. I am honored by the opportunity to contribute an article to the Julius Wess Memorial Volume. I will review theoretical developments of the recent years in non-perturbative supersymmetry.
Sojourn time approximations for a multi-server processor sharing system with priorities
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
International Nuclear Information System (INIS)
Schall, Dominik L.; Wolf, Menas; Mohnen, Alwine
2016-01-01
Increasing energy efficiency is a cornerstone of policy initiatives to tackle climate change and increase corporate sustainability. Convincing people to drive more fuel-efficiently (“eco-driving”) is often an integral part of these approaches, especially in the transport sector. But there is a lack of studies on the long-term persistence and potential interaction of the effects of incentives and training on energy conservation behavior in general and eco-driving behavior in particular. We address this gap with a twelve months long natural field experiment in a logistics company to analyze the time-dependent and potentially interacting effects of rewards and theoretical training for eco-driving on fuel consumption in a real-world setting. We find an immediate reduction of fuel consumption following the introduction of a non-monetary reward and an attenuation of this effect over time. Theoretical eco-driving training shows no effect, neither short-term nor long-term, highlighting the often neglected necessity to include practical training elements. Contrary to common assumptions, the interaction of incentives and theoretical training does not show an additional reduction effect. Our results demonstrate the difficulty of changing engrained behavior and habits, and underline the need for a careful selection and combination of interventions. Policy implications for public and private actors are discussed. - Highlights: • Natural field experiment on training and incentives for fuel-efficient driving. • Focus on long-term and interaction effects over twelve months. • Immediate reduction effect of non-monetary reward that attenuates over time. • Theoretical eco-driving training shows no effect, neither short-term nor long-term. • Interaction of incentives and training shows no additional reduction effect.
Enhanced round robin CPU scheduling with burst time based time quantum
Indusree, J. R.; Prabadevi, B.
2017-11-01
Process scheduling is a very important functionality of Operating system. The main-known process-scheduling algorithms are First Come First Serve (FCFS) algorithm, Round Robin (RR) algorithm, Priority scheduling algorithm and Shortest Job First (SJF) algorithm. Compared to its peers, Round Robin (RR) algorithm has the advantage that it gives fair share of CPU to the processes which are already in the ready-queue. The effectiveness of the RR algorithm greatly depends on chosen time quantum value. Through this research paper, we are proposing an enhanced algorithm called Enhanced Round Robin with Burst-time based Time Quantum (ERRBTQ) process scheduling algorithm which calculates time quantum as per the burst-time of processes already in ready queue. The experimental results and analysis of ERRBTQ algorithm clearly indicates the improved performance when compared with conventional RR and its variants.
International Nuclear Information System (INIS)
Orlov, V.V.; Slesarev, I.S.; Zaritskij, S.M.; Subbotin, S.A.; Alekseev, P.N.; Zverkov, Yu.A.
1980-01-01
The authors have derived approximate expressions relating the doubling time of a fast reactor using various types of fuel simultaneously to the doubling time of traditional (homogeneous) reactors in which these types of fuel are used separately. These relationships afford a means of determining the conditions in which the use of various types of fuel can result in an improved doubling time. It was established that the use of heterogeneous compositions formed from assemblies of homogeneous systems gives a notable gain in doubling time over that of any of the original homogeneous systems if the doubling times were similar to each other. This gain is fairly large even in the case of BN reactors with high fuel volume fractions. The size of the gain depends on the degree of ''differentiation'' in the neutron and thermal properties of the components of the heterogeneous reactor. An optimum proportion has been found for the assemblies taken from the original homogeneous systems, governed primarily by the ratio of fuel densities. Estimates were made of the advantages of metallic oxide compositions over the traditional compositions used in large, fast reactors of the BN type. These estimates indicate that the former can be considered as alternative homogeneous compositions with carbide or nitride fuel as far as breeding characteristics are concerned. (author)
Directory of Open Access Journals (Sweden)
O. V. Nevdachyna
2016-01-01
Full Text Available The paper presents an approach to solving the overloading problem in TCP/IP networks. Offered fuzzy controller with two inputs for system of active queue management packages in TCP/IP networks, and investigated its use in these systems with a random change of traffic load. Proposed controller has two inputs, one of which is the value of the difference between the current queue length and the second – the difference between the current level of usage of the buffer. The output of the fuzzy controller calculates the probability of discarding packet.Mathematical model system of active queue management that is studied is presented in an interactive MATLAB system, in wherein also is demonstrated the processes occurring in the system with a random change of traffic load. The research results show that the AQM-system with fuzzy controller with two entrances stable enough maintains the desired current length the queue for sufficiently small values of the probability of dropping/marking packets (at acceptable size of queue q0= 200 packets, the average probability of dropping / marking is not more than 3,5×10–3 or less 0,35% packets is discarded or marked from the total number of incoming packets. The results obtained will help improve the efficiency of the functioning and operation of TCP / IP networks by increasing data transmission quality. this happens due introduction of the proposed controller at the design of new, more efficient routers for networks to minimize the delay of information.
Analysis of Two-Level Support Systems with Time-Dependent Overflow - A Banking Application
DEFF Research Database (Denmark)
Barth, Wolfgang; Manitz, Michael; Stolletz, Raik
2010-01-01
In this paper, we analyze the performance of call centers of financial service providers with two levels of support and a time-dependent overflow mechanism. Waiting calls from the front-office queue flow over to the back office if a waiting-time limit is reached and at least one back-office agent...
International Nuclear Information System (INIS)
Heintze, E.
1993-01-01
The aim of this report is to present a method for solving the time-domain three-dimensional Maxwell equations. This method is based on a variational formulation and can be easily coupled with a particle solver for the Vlasov equation. The necessity to take into account complex three-dimensional geometries and to have a spatial resolution fitted to the various computation zones, leads to choose a finite element method built on tetrahedral unstructured meshes. 12 refs
Liu, Nan; D'Aunno, Thomas
2012-04-01
To develop simple stylized models for evaluating the productivity and cost-efficiencies of different practice models to involve nurse practitioners (NPs) in primary care, and in particular to generate insights on what affects the performance of these models and how. The productivity of a practice model is defined as the maximum number of patients that can be accounted for by the model under a given timeliness-to-care requirement; cost-efficiency is measured by the corresponding annual cost per patient in that model. Appropriate queueing analysis is conducted to generate formulas and values for these two performance measures. Model parameters for the analysis are extracted from the previous literature and survey reports. Sensitivity analysis is conducted to investigate the model performance under different scenarios and to verify the robustness of findings. Employing an NP, whose salary is usually lower than a primary care physician, may not be cost-efficient, in particular when the NP's capacity is underutilized. Besides provider service rates, workload allocation among providers is one of the most important determinants for the cost-efficiency of a practice model involving NPs. Capacity pooling among providers could be a helpful strategy to improve efficiency in care delivery. The productivity and cost-efficiency of a practice model depend heavily on how providers organize their work and a variety of other factors related to the practice environment. Queueing theory provides useful tools to take into account these factors in making strategic decisions on staffing and panel size selection for a practice model. © Health Research and Educational Trust.
Fawzy, Diaa E.; Stȩpień, K.
2018-03-01
In the current study we present ab initio numerical computations of the generation and propagation of longitudinal waves in magnetic flux tubes embedded in the atmospheres of late-type stars. The interaction between convective turbulence and the magnetic structure is computed and the obtained longitudinal wave energy flux is used in a self-consistent manner to excite the small-scale magnetic flux tubes. In the current study we reduce the number of assumptions made in our previous studies by considering the full magnetic wave energy fluxes and spectra as well as time-dependent ionization (TDI) of hydrogen, employing multi-level Ca II atomic models, and taking into account departures from local thermodynamic equilibrium. Our models employ the recently confirmed value of the mixing-length parameter α=1.8. Regions with strong magnetic fields (magnetic filling factors of up to 50%) are also considered in the current study. The computed Ca II emission fluxes show a strong dependence on the magnetic filling factors, and the effect of time-dependent ionization (TDI) turns out to be very important in the atmospheres of late-type stars heated by acoustic and magnetic waves. The emitted Ca II fluxes with TDI included into the model are decreased by factors that range from 1.4 to 5.5 for G0V and M0V stars, respectively, compared to models that do not consider TDI. The results of our computations are compared with observations. Excellent agreement between the observed and predicted basal flux is obtained. The predicted trend of Ca II emission flux with magnetic filling factor and stellar surface temperature also agrees well with the observations but the calculated maximum fluxes for stars of different spectral types are about two times lower than observations. Though the longitudinal MHD waves considered here are important for chromosphere heating in high activity stars, additional heating mechanism(s) are apparently present.
2014-01-01
WE RECOMMEND Nuclear Radiation DVD is an excellent introduction to nuclear radiation WORTH A LOOK The Theoretical Minimum and Time Reborn Can mathematics be the key to reality? Cobra4 Data Logger Apparatus provides an extensive collection of sensors Stuff Matters Materials book deserves a wide readership Hunting the Higgs Higgs book a bit light on detail but good for visits to CERN My Brief History Hawking's book is readable but inconclusive APPS Using apps to help students visualize fields WEB WATCH Vintage film of Eric Laithwaite ... induction hobs as an example of electromagnetic induction ... the deconstruction of a CRO tube ... the Brocken spectre ... the Square Kilometre Array telescope
Manning, Robert M.
2016-01-01
As satellite communications systems become both more complex and reliant with respect to their operating environment, it has become imperative to be able to identify, during real-time operation, the onset of one or more impairments to the quality of overall communications system integrity. One of the most important aspects to monitor of a satellite link operating within the Earth's atmosphere is the signal fading due to the occurrence of rain and/or phase scintillations. This, of course, must be done in the presence of the associated measurement uncertainty or potentially faulty measurement equipment such as in the Advanced Communication Technology Satellite (ACTS) experiment. In the present work, an approach originally suggested in 1991, and apparently still considered iconoclastic, will be significantly developed and applied to the satellite communications link on which the deleterious composite signal fade is the result of one or many component fade mechanisms. Through the measurement (with the attendant uncertainty or 'error' in the measurement) of such a composite fading satellite signal, it is desired to extract the level of each of the individual fading mechanisms so they can be appropriately mitigated before they impact the overall performance of the communications network. Rather than employing simple-minded deterministic filtering to the real-time fading, the present approach is built around all the models and/or descriptions used to describe the individual fade components, including their dynamic evolution. The latter is usually given by a first-order Langevin equation. This circumstance allows the description of the associated temporal transition probability densities of each of the component processes. By using this description, along with the real-time measurements of the composite fade (along with the measurement errors), one can obtain statistical estimates of the levels of each of the component fading mechanisms as well as their predicted values
International Nuclear Information System (INIS)
Amin, Mohammed A.; Ahmed, M.A.; Arida, H.A.; Kandemirli, Fatma; Saracoglu, Murat; Arslan, Taner; Basaran, Murat A.
2011-01-01
Graphical abstract: . Display Omitted Research highlights: → The inhibition effect of TX-100, TX-165 and TX-305 on iron corrosion in 1.0 M HCl was studied. → TX-305 inhibited iron corrosion more effectively than TX-100 and TX-165. → In most cases, inhibition efficiency increased with time during the first 60 min of immersion, then decreased. → Calculated quantum chemical parameters confirmed the experimental inhibition efficiencies of the tested surfactants. - Abstract: The inhibition performance of three selected non-ionic surfactants of the TRITON-X series, namely TRITONX-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on the corrosion of iron was studied in 1.0 M HCl solutions as a function of inhibitor concentration (0.01-0.20 g L -1 ) and immersion time (0.0-8 h) at 298 K. Measurements were conducted based on Tafel polarization, LPR and impedance studies. At high frequencies, the impedance spectrum showed a depressed capacitive loop in the complex impedance plane, whose diameter is a function of the immersion time and the type and concentration of the introduced surfactant. In all cases, an inductive loop was observed in the low frequency and this could be attributed to the adsorption behavior. The inhibition efficiency increased with immersion time, reached a maximum and then decreased. This was attributed to the orientation change of adsorbed surfactant molecules. TX-305 inhibited iron corrosion more effectively than TX-100 and TX-165. The frontier orbital energies, the energy gap between frontier orbitals, dipole moments (μ), charges on the C and O atoms, the polarizabilities, and the quantum chemical descriptors were calculated. The quantum chemical calculation results inferred that for the HOMO representing the condensed Fukui function for an electrophilic attack (f k + ), the contributions belong to the phenyl group and the oxygen atom attached to the phenyl group for each tested surfactant. Quantitative structure
Directory of Open Access Journals (Sweden)
Pryo Utomo
2017-06-01
Full Text Available One Time Pad (OTP is a cryptographic algorithm that is quite easy to be implemented. This algorithm works by converting plaintext and key into decimal then converting into binary number and calculating Exclusive-OR logic. In this paper, the authors try to make the comparison of OTP cryptography using KPI and KCT so that the ciphertext will be generated more difficult to be known. In the Key and Plaintext Insertion (KPI Method, we modify the OTP algorithm by adding the key insertion in the plaintext that has been splitted. Meanwhile in the Key Coloumnar Transposition (KCT Method, we modify the OTP algorithm by dividing the key into some parts in matrix of rows and coloumns. Implementation of the algorithms using PHP programming language.
2010-03-01
Incidents account for a large portion of all congestion and a need clearly exists for tools to predict and estimate incident effects. This study examined (1) congestion back propagation to estimate the length of the queue and travel time from upstrea...
Palm theory for random time changes
Directory of Open Access Journals (Sweden)
Masakiyo Miyazawa
2001-01-01
Full Text Available Palm distributions are basic tools when studying stationarity in the context of point processes, queueing systems, fluid queues or random measures. The framework varies with the random phenomenon of interest, but usually a one-dimensional group of measure-preserving shifts is the starting point. In the present paper, by alternatively using a framework involving random time changes (RTCs and a two-dimensional family of shifts, we are able to characterize all of the above systems in a single framework. Moreover, this leads to what we call the detailed Palm distribution (DPD which is stationary with respect to a certain group of shifts. The DPD has a very natural interpretation as the distribution seen at a randomly chosen position on the extended graph of the RTC, and satisfies a general duality criterion: the DPD of the DPD gives the underlying probability P in return.
Marchese, Anthony J.; Dryer, Fredrick L.; Choi, Mun Y.
1994-01-01
In order to develop an extensive envelope of test conditions for NASA's space-based Droplet Combustion Experiment (DCE) as well those droplet experiments which can be performed using a drop tower, the transient vaporization and combustion of methanol and n-heptane droplets were simulated using a recently developed fully time-dependent, spherically symmetric droplet combustion model. The transient vaporization of methanol and n-heptane was modeled to characterize the instantaneous gas phase composition surrounding the droplet prior to the introduction of an ignition source. The results for methanol/air showed that the entire gas phase surrounding a 2 mm methanol droplet deployed in zero-g .quickly falls outside the lean flammability limit. The gas phase surrounding an identically-sized n-heptane droplet, on the other hand, remains flammable. The combustion of methanol was then modeled considering a detailed gas phase chemical kinetic mechanism (168 steps, 26 species) and the effect of the dissolution of flame-generated water into the liquid droplet. These results were used to determine the critical ignition diameter required to achieve quasi-steady droplet combustion in a given oxidizing environment. For droplet diameters greater than the critical ignition diameter, the model predicted a finite diameter at which the flame would extinguish. These extinction diameters were found to vary significantly with initial droplet diameter. This phenomenon appears to be unique to the transient heat transfer, mass transfer and chemical kinetics of the system and thus has not been reported elsewhere to date. The extinction diameter was also shown to vary significantly with the liquid phase Lewis number since the amount of water present in the droplet at extinction is largely governed by the rate at which water is transported into the droplet via mass diffusion. Finally, the numerical results for n-heptane combustion were obtained using both 2 step and 96 step semi
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.
Optimal hysteretic control for a B M A P / S M / 1 / N queue with two operation modes
Directory of Open Access Journals (Sweden)
Dudin Alexander N.
1999-01-01
Full Text Available We consider B M A P / S M / 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 B M A P -input, the kernel of the semi-Markovian service process, and utilization cost. An algorithm for determining the optimal hysteresis strategy is presented.
Theoretical solid state physics
International Nuclear Information System (INIS)
Anon.
1977-01-01
Research activities at ORNL in theoretical solid state physics are described. Topics covered include: surface studies; particle-solid interactions; electronic and magnetic properties; and lattice dynamics
Natsume, Takahiro; Ishida, Masaki; Kitagawa, Kakuya; Nagata, Motonori; Sakuma, Hajime; Ichihara, Takashi
2015-11-01
The purpose of this study was to develop a method to determine time discrepancies between input and myocardial time-signal intensity (TSI) curves for accurate estimation of myocardial perfusion with first-pass contrast-enhanced MRI. Estimation of myocardial perfusion with contrast-enhanced MRI using kinetic models requires faithful recording of contrast content in the blood and myocardium. Typically, the arterial input function (AIF) is obtained by setting a region of interest in the left ventricular cavity. However, there is a small delay between the AIF and the myocardial curves, and such time discrepancies can lead to errors in flow estimation using Patlak plot analysis. In this study, the time discrepancies between the arterial TSI curve and the myocardial tissue TSI curve were estimated based on the compartment model. In the early phase after the arrival of the contrast agent in the myocardium, the relationship between rate constant K1 and the concentrations of Gd-DTPA contrast agent in the myocardium and arterial blood (LV blood) can be described by the equation K1={dCmyo(tpeak)/dt}/Ca(tpeak), where Cmyo(t) and Ca(t) are the relative concentrations of Gd-DTPA contrast agent in the myocardium and in the LV blood, respectively, and tpeak is the time corresponding to the peak of Ca(t). In the ideal case, the time corresponding to the maximum upslope of Cmyo(t), tmax, is equal to tpeak. In practice, however, there is a small difference in the arrival times of the contrast agent into the LV and into the myocardium. This difference was estimated to correspond to the difference between tpeak and tmax. The magnitudes of such time discrepancies and the effectiveness of the correction for these time discrepancies were measured in 18 subjects who underwent myocardial perfusion MRI under rest and stress conditions. The effects of the time discrepancies could be corrected effectively in the myocardial perfusion estimates. Copyright © 2015 Elsevier Inc. All rights
International Nuclear Information System (INIS)
This report is a survey of the studies done in the Theoretical Physics Division of the Nuclear Physics Institute; the subjects studied in theoretical nuclear physics were the few-nucleon problem, nuclear structure, nuclear reactions, weak interactions, intermediate energy and high energy physics. In this last field, the subjects studied were field theory, group theory, symmetry and strong interactions [fr
Theoretical Approaches to Coping
Directory of Open Access Journals (Sweden)
Sofia Zyga
2013-01-01
Full Text Available Introduction: Dealing with stress requires conscious effort, it cannot be perceived as equal to individual's spontaneous reactions. The intentional management of stress must not be confused withdefense mechanisms. Coping differs from adjustment in that the latter is more general, has a broader meaning and includes diverse ways of facing a difficulty.Aim: An exploration of the definition of the term "coping", the function of the coping process as well as its differentiation from other similar meanings through a literature review.Methodology: Three theoretical approaches of coping are introduced; the psychoanalytic approach; approaching by characteristics; and the Lazarus and Folkman interactive model.Results: The strategic methods of the coping approaches are described and the article ends with a review of the approaches including the functioning of the stress-coping process , the classificationtypes of coping strategies in stress-inducing situations and with a criticism of coping approaches.Conclusions: The comparison of coping in different situations is difficult, if not impossible. The coping process is a slow process, so an individual may select one method of coping under one set ofcircumstances and a different strategy at some other time. Such selection of strategies takes place as the situation changes.
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.
Blatt, John M
1979-01-01
A classic work by two leading physicists and scientific educators endures as an uncommonly clear and cogent investigation and correlation of key aspects of theoretical nuclear physics. It is probably the most widely adopted book on the subject. The authors approach the subject as ""the theoretical concepts, methods, and considerations which have been devised in order to interpret the experimental material and to advance our ability to predict and control nuclear phenomena.""The present volume does not pretend to cover all aspects of theoretical nuclear physics. Its coverage is restricted to
International Nuclear Information System (INIS)
Anon.
1980-01-01
Research activities of the theoretical physics division for 1979 are described. Short summaries are given of specific research work in the following fields: nuclear structure, nuclear reactions, intermediate energy physics, elementary particles [fr
DEFF Research Database (Denmark)
2002-01-01
The proceedings contains 8 papers from the Conference on Theoretical Computer Science. Topics discussed include: query by committee, linear separation and random walks; hardness results for neural network approximation problems; a geometric approach to leveraging weak learners; mind change...
International Nuclear Information System (INIS)
Anon.
The studies in 1977 are reviewed. In theoretical nuclear physics: nuclear structure, nuclear reactions, intermediate energy physics; in elementary particle physics: field theory, strong interactions dynamics, nucleon-nucleon interactions, new particles, current algebra, symmetries and quarks are studied [fr
Theoretical physics and astrophysics
Ginzburg, Vitalii Lazarevich
1979-01-01
The aim of this book is to present, on the one hand various topics in theoretical physics in depth - especially topics related to electrodynamics - and on the other hand to show how these topics find applications in various aspects of astrophysics. The first text on theoretical physics and astrophysical applications, it covers many recent advances including those in X-ray, &ggr;-ray and radio-astronomy, with comprehensive coverage of the literature
Extremes of Markov-additive processes with one-sided jumps, with queueing applications
A.B. Dieker (Ton); M.R.H. Mandjes (Michel)
2009-01-01
htmlabstractThrough Laplace transforms, we study the extremes of a continuous-time Markov-additive pro- cess with one-sided jumps and a finite-state background Markovian state-space, jointly with the epoch at which the extreme is ‘attained’. For this, we investigate discrete-time Markov-additive
Convergence of a Queueing System in Heavy Traffic with General Abandonment Distributions
2010-10-08
on the limiting diffusion. One key ingredient in our proof of Theorem 4.8 is the martingale functional central limit theorem, and this approach helps...intensity dependent on offered waiting time, and introduce the key martingale relevant to the arrival process. Such a martingale formulation is used...diffusion limit for the scaled offered waiting time process. Main result in this section is Theorem 4.8, and we use martingale functional central limit
Response Time Analysis of Distributed Web Systems Using QPNs
Directory of Open Access Journals (Sweden)
Tomasz Rak
2015-01-01
Full Text Available A performance model is used for studying distributed Web systems. Performance evaluation is done by obtaining load test measurements. Queueing Petri Nets formalism supports modeling and performance analysis of distributed World Wide Web environments. The proposed distributed Web systems modeling and design methodology have been applied in the evaluation of several system architectures under different external loads. Furthermore, performance analysis is done to determine the system response time.
Directory of Open Access Journals (Sweden)
Yi Zhao
2015-01-01
Full Text Available This study aimed to calibrate saturation flow rate (SFR and start-up lost time (SLT when developing signal timing. In current commonly used methods, SFR for one given lane is usually calibrated from many subjective adjustment factors and a fixed result. SLT is calculated based on the fixed SFR, which prevents local applications in China. Considering the importance of traffic behavior (headway in determining SFR and SLT, this study started from headway distribution and attempted to specify the relationships between headway and vehicle position directly. A common intersection in Nanjing, China, was selected to implement field study and data from 920 queues was collected. Headway distribution was explored and the 78th percentile of headway at each position was selected to build model. Based on the developed relationships, SFR and SLT were calibrated. The results showed that SFR and SLT were correlated with queue length. Moreover, the results showed that it was difficult to reach saturated state even with a long queue length. This paper provides a new perspective on calibrating important parameters in signal timing, which will be useful for traffic agencies to complete signal timing by making the process simpler.
Information Theoretic Subspace Clustering.
He, Ran; Wang, Liang; Sun, Zhenan; Zhang, Yingya; Li, Bo
2016-12-01
This paper addresses the problem of grouping the data points sampled from a union of multiple subspaces in the presence of outliers. Information theoretic objective functions are proposed to combine structured low-rank representations (LRRs) to capture the global structure of data and information theoretic measures to handle outliers. In theoretical part, we point out that group sparsity-induced measures ( l 2,1 -norm, l α -norm, and correntropy) can be justified from the viewpoint of half-quadratic (HQ) optimization, which facilitates both convergence study and algorithmic development. In particular, a general formulation is accordingly proposed to unify HQ-based group sparsity methods into a common framework. In algorithmic part, we develop information theoretic subspace clustering methods via correntropy. With the help of Parzen window estimation, correntropy is used to handle either outliers under any distributions or sample-specific errors in data. Pairwise link constraints are further treated as a prior structure of LRRs. Based on the HQ framework, iterative algorithms are developed to solve the nonconvex information theoretic loss functions. Experimental results on three benchmark databases show that our methods can further improve the robustness of LRR subspace clustering and outperform other state-of-the-art subspace clustering methods.
Analysis of Queues with Rational Arrival Process Components - A General Approach
DEFF Research Database (Denmark)
Bean, Nigel; Nielsen, Bo Friis
the matrix-geometric form for a certain kind of operators on the stationary measure for discrete time Markov chains of GI/M/1 type. We apply this result to an embedded chain with RAP components. We then discuss the straight- forward modification of the standard algorithms for calculating the matrix R...
Theoretical Chemistry Symposium 2006
Indian Academy of Sciences (India)
WINTEC
This special issue of the Journal of Chemical Sciences contains 29 original papers presented at the Theoretical Chemistry Symposium (TCS 2006) held at Bharathi- dasan University during December 11–13, 2006. Earlier meetings on this theme were organized in various parts of the country viz. Chandigarh (1986), IIT ...
DEFF Research Database (Denmark)
2002-01-01
The proceedings contains 8 papers from the Conference on Theoretical Computer Science. Topics discussed include: query by committee, linear separation and random walks; hardness results for neural network approximation problems; a geometric approach to leveraging weak learners; mind change...... complexity of learning logic programs and avoiding coding tricks by hyperrobust learning....
Riemann and Theoretical Physics
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 11. Riemann and Theoretical Physics. Joseph Samuel. General Article Volume 11 Issue 11 November 2006 pp 56-60. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/011/11/0056-0060. Keywords.
Spectrum Handoffs Based on Preemptive Repeat Priority Queue in Cognitive Radio Networks.
Yang, Xiaolong; Tan, Xuezhi; Ye, Liang; Ma, Lin
2016-07-20
Cognitive radio can significantly improve the spectrum efficiency, and spectrum handoff is considered as an important functionality to guarantee the quality of service (QoS) of primary users (PUs) and the continuity of data transmission of secondary users (SUs). In this paper, we propose an analytical framework based on a preemptive repeat identical (PRI) M/G/1 queuing network model to characterize spectrum handoff behaviors with general service time distribution of both primary and secondary connections, multiple interruptions and transmission delay resulting from the appearance of primary connections. Then, we derive the close-expression of the extended data delivery and the system sojourn time in both staying and changing scenarios. In addition, based on analysis of spectrum handoff behaviors resulting from multiple interruptions caused by the appearance of the primary connections, we investigate the traffic-adaptive policy, by which the considered SU will optimally adjust its handoff spectrum policy. Moreover, we investigate the admissible region and provide the reference for designing the admission control rule for the arriving secondary connection requests. Finally, simulation results verify that our proposed analytical framework is reasonable and can provide the reference for executing the optimal spectrum handoff strategy and designing the admission control rule for the SU in cognitive radio networks.
A RED modified weighted moving average for soft real-time application
Directory of Open Access Journals (Sweden)
Domanśka Joanna
2014-09-01
Full Text Available The popularity of TCP/IP has resulted in an increase in usage of best-effort networks for real-time communication. Much effort has been spent to ensure quality of service for soft real-time traffic over IP networks. The Internet Engineering Task Force has proposed some architecture components, such as Active Queue Management (AQM. The paper investigates the influence of the weighted moving average on packet waiting time reduction for an AQM mechanism: the RED algorithm. The proposed method for computing the average queue length is based on a difference equation (a recursive equation. Depending on a particular optimality criterion, proper parameters of the modified weighted moving average function can be chosen. This change will allow reducing the number of violations of timing constraints and better use of this mechanism for soft real-time transmissions. The optimization problem is solved through simulations performed in OMNeT++ and later verified experimentally on a Linux implementation
Investigations on the discrete Gi(G)1 queue with and without loss
International Nuclear Information System (INIS)
Gergely, T.; Toeroek, T.L.
1975-12-01
A comprehensive discussion of the method for investigating queuing systems characterized by random variables of integer values is given. Specially the discrete GI(G)1 queuing systems are considered. The first part of the paper takes a short summary on the theory of discrete stochastic processes. In the second part the properties of the fundamental characteristics of the queuing system as the busy period, the waiting time and the output processes are discussed. In the last section some remarks are added to show the direction of further investigations. To demonstrated the simplicity of the relations verified in the paper some computed examples are presented in the appendix. The computations were performed with a mini-computer of 8K words memory. (Sz.Z.)
Energy Technology Data Exchange (ETDEWEB)
Cohen, Andrew [Boston Univ., MA (United States); Schmaltz, Martin [Boston Univ., MA (United States); Katz, Emmanuel [Boston Univ., MA (United States); Rebbi, Claudio [Boston Univ., MA (United States); Glashow, Sheldon [Boston Univ., MA (United States); Brower, Richard [Boston Univ., MA (United States); Pi, So-Young [Boston Univ., MA (United States)
2016-09-30
interactions between quark and gluon particles, we have no clear idea how to express the proton state in terms of these quarks and gluons. This is because the proton, though a bound state of quarks and gluons, is not a state of a fixed number of particles due to strong interactions. Yet, understanding the proton state is very important in order to theoretically predict the reaction rates observed at the LHC in Geneva, which is a proton-proton collider. Katz has formulated a new approach to QFT, which among other things offers a way to adequately approximate the quantum wave function of a bound state at strong coupling. The approximation scheme is related to the fact that any sensible QFT (including that of the strong interactions) is at short distances approximately self-similar upon rescaling of space and time. It turns out that keeping track of the response upon this rescaling is important in efficiently parameterizing the state. Katz and collaborators have used this observation to approximate the state of the proton in toy versions of the strong force. In the late 60s Sheldon Glashow, Abdus Salam and Steven Weinberg (1979 Nobel Prize awardees) proposed a theory unifying weak and electromagnetic interaction which assumed the existence of new particles, the W and Z bosons. The W and Z bosons were eventually detected in high-energy collision in a particle accelerator at CERN, and the recent discovery of the Higgs meson at the Large Hadron Collider (LHC), always at CERN, completed the picture. However, deep theoretical considerations indicate that the theory by Glashow, Weinberg and Salam, often referred to as "the standard model" cannot be the whole story: the existence of new particles and new interactions at yet higher energies is widely anticipated. The experiments at the LHC are looking for these, while theorists, like Brower, Rebbi and collaborators, are investigating models for these new interactions. Working in a large national collaboration with access to the most
Zero-Error Capacity of a Class of Timing Channels
DEFF Research Database (Denmark)
Kovacevic, M.; Popovski, Petar
2014-01-01
We analyze the problem of zero-error communication through timing channels that can be interpreted as discrete-time queues with bounded waiting times. The channel model includes the following assumptions: 1) time is slotted; 2) at most N particles are sent in each time slot; 3) every particle is ...... constructed, and a linear-time decoding algorithm for these codes devised. In the particular case N = 1, K = 1, the capacity is equal to φ, where φ = (1 + √5)/2 is the golden ratio, and constructed codes give another interpretation of the Fibonacci sequence....
Max-Min Optimality of Service Rate Control in Closed Queueing Networks
Xia, Li
2013-04-01
In this technical note, we discuss the optimality properties of service rate control in closed Jackson networks. We prove that when the cost function is linear to a particular service rate, the system performance is monotonic w.r.t. (with respect to) that service rate and the optimal value of that service rate can be either maximum or minimum (we call it Max-Min optimality); When the second-order derivative of the cost function w.r.t. a particular service rate is always positive (negative), which makes the cost function strictly convex (concave), the optimal value of such service rate for the performance maximization (minimization) problem can be either maximum or minimum. To the best of our knowledge, this is the most general result for the optimality of service rates in closed Jackson networks and all the previous works only involve the first conclusion. Moreover, our result is also valid for both the state-dependent and load-dependent service rates, under both the time-average and customer-average performance criteria.
Friedrich, Harald
2017-01-01
This expanded and updated well-established textbook contains an advanced presentation of quantum mechanics adapted to the requirements of modern atomic physics. It includes topics of current interest such as semiclassical theory, chaos, atom optics and Bose-Einstein condensation in atomic gases. In order to facilitate the consolidation of the material covered, various problems are included, together with complete solutions. The emphasis on theory enables the reader to appreciate the fundamental assumptions underlying standard theoretical constructs and to embark on independent research projects. The fourth edition of Theoretical Atomic Physics contains an updated treatment of the sections involving scattering theory and near-threshold phenomena manifest in the behaviour of cold atoms (and molecules). Special attention is given to the quantization of weakly bound states just below the continuum threshold and to low-energy scattering and quantum reflection just above. Particular emphasis is laid on the fundamen...
Concluding theoretical remarks
International Nuclear Information System (INIS)
Ellis, J.
1986-01-01
My task in this talk is to review the happenings of this workshop from a theoretical perspective, and to emphasize lines for possible future research. My remarks are organized into a theoretical overview of the what, why, (mainly the hierarchy problem) how, (supersymmetry must be broken: softly or spontaneously, and if the latter, by means of a new U tilde(1) gauge group or through the chiral superfields) when (how heavy are supersymmetric partner particles in different types of theories) and where (can one find evidence for) supersymmetry. In the last part are discussed various ongoing and future searches for photinos γ tilde, gravitinos G tilde, the U vector boson, shiggses H tilde, squarks q tilde and sleptons l tilde, gluinos g tilde, winos W tilde and other gauginos, as well as hunts for indirect effects of supersymmetry, such as for example in baryon decay. Finally there is a little message of encouragement to our experimental colleagues, based on historical precedent. (orig.)
Compendium of theoretical physics
Wachter, Armin
2006-01-01
Mechanics, Electrodynamics, Quantum Mechanics, and Statistical Mechanics and Thermodynamics comprise the canonical undergraduate curriculum of theoretical physics. In Compendium of Theoretical Physics, Armin Wachter and Henning Hoeber offer a concise, rigorous and structured overview that will be invaluable for students preparing for their qualifying examinations, readers needing a supplement to standard textbooks, and research or industrial physicists seeking a bridge between extensive textbooks and formula books. The authors take an axiomatic-deductive approach to each topic, starting the discussion of each theory with its fundamental equations. By subsequently deriving the various physical relationships and laws in logical rather than chronological order, and by using a consistent presentation and notation throughout, they emphasize the connections between the individual theories. The reader’s understanding is then reinforced with exercises, solutions and topic summaries. Unique Features: Every topic is ...
Silicene: Recent theoretical advances
Lew Yan Voon, L. C.
2016-04-14
Silicene is a two-dimensional allotrope of silicon with a puckered hexagonal structure closely related to the structure of graphene and that has been predicted to be stable. To date, it has been successfully grown in solution (functionalized) and on substrates. The goal of this review is to provide a summary of recent theoretical advances in the properties of both free-standing silicene as well as in interaction with molecules and substrates, and of proposed device applications.
3. Theoretical Physics Division
International Nuclear Information System (INIS)
For the period September 1980 - Aug 1981, the studies in theoretical physics divisions have been compiled under the following headings: in nuclear physics, nuclear structure, nuclear reactions and intermediate energies; in particle physics, NN and NantiN interactions, dual topological unitarization, quark model and quantum chromodynamics, classical and quantum field theories, non linear integrable equations and topological preons and Grand unified theories. A list of publications, lectures and meetings is included [fr
Theoretical high energy physics
International Nuclear Information System (INIS)
Lee, T.D.
1990-05-01
This report discusses progress on theoretical high energy physics at Columbia University in New York City. Some of the topics covered are: Chern-Simons gauge field theories; dynamical fermion QCD calculations; lattice gauge theory; the standard model of weak and electromagnetic interactions; Boson-fermion model of cuprate superconductors; S-channel theory of superconductivity and axial anomaly and its relation to spin in the parton model
A microscopic investigation into capacity drop: impacts of a bunded acceleration and reaction time
Yuan, K.; Knoop, V.L.; Hoogendoorn, S.P.
2016-01-01
Capacity drop indicates that the queue discharge rate is lower than the road capacity. Due to the capacity drop, traffic delays increase once queues form. Researchers find that queue discharge rates vary in different traffic conditions. Empirical data shows that the queue discharge rate increases as
Information theoretic preattentive saliency
DEFF Research Database (Denmark)
Loog, Marco
2011-01-01
Employing an information theoretic operational definition of bottom-up attention from the field of computational visual perception a very general expression for saliency is provided. As opposed to many of the current approaches to determining a saliency map there is no need for an explicit data...... of which features, image information is described. We illustrate our result by determining a few specific saliency maps based on particular choices of features. One of them makes the link with the mapping underlying well-known Harris interest points, which is a result recently obtained in isolation...
Institute for Theoretical Physics
Energy Technology Data Exchange (ETDEWEB)
Giddings, S.B.; Ooguri, H.; Peet, A.W.; Schwarz, J.H.
1998-06-01
String theory is the only serious candidate for a unified description of all known fundamental particles and interactions, including gravity, in a single theoretical framework. Over the past two years, activity in this subject has grown rapidly, thanks to dramatic advances in understanding the dynamics of supersymmetric field theories and string theories. The cornerstone of these new developments is the discovery of duality which relates apparently different string theories and transforms difficult strongly coupled problems of one theory into weakly coupled problems of another theory.
Theoretical solid state physics
Haug, Albert
2013-01-01
Theoretical Solid State Physics, Volume 1 focuses on the study of solid state physics. The volume first takes a look at the basic concepts and structures of solid state physics, including potential energies of solids, concept and classification of solids, and crystal structure. The book then explains single-electron approximation wherein the methods for calculating energy bands; electron in the field of crystal atoms; laws of motion of the electrons in solids; and electron statistics are discussed. The text describes general forms of solutions and relationships, including collective electron i
Theoretical Optics An Introduction
Römer, Hartmann
2004-01-01
Starting from basic electrodynamics, this volume provides a solid, yet concise introduction to theoretical optics, containing topics such as nonlinear optics, light-matter interaction, and modern topics in quantum optics, including entanglement, cryptography, and quantum computation. The author, with many years of experience in teaching and research, goes way beyond the scope of traditional lectures, enabling readers to keep up with the current state of knowledge. Both content and presentation make it essential reading for graduate and phD students as well as a valuable reference for researche
Theoretical high energy physics
International Nuclear Information System (INIS)
Lee, T.D.
1991-01-01
This report discusses theoretical research in high energy physics at Columbia University. Some of the research topics discussed are: quantum chromodynamics with dynamical fermions; lattice gauge theory; scattering of neutrinos by photons; atomic physics constraints on the properties of ultralight-ultraweak gauge bosons; black holes; Chern- Simons physics; S-channel theory of superconductivity; charged boson system; gluon-gluon interactions; high energy scattering in the presence of instantons; anyon physics; causality constraints on primordial magnetic manopoles; charged black holes with scalar hair; properties of Chern-Aimona-Higgs solitons; and extended inflationary universe
Theoretical astrophysics an introduction
Bartelmann, Matthias
2013-01-01
A concise yet comprehensive introduction to the central theoretical concepts of modern astrophysics, presenting hydrodynamics, radiation, and stellar dynamics all in one textbook. Adopting a modular structure, the author illustrates a small number of fundamental physical methods and principles, which are sufficient to describe and understand a wide range of seemingly very diverse astrophysical phenomena and processes. For example, the formulae that define the macroscopic behavior of stellar systems are all derived in the same way from the microscopic distribution function. This function it
Shivamoggi, Bhimsen K
1998-01-01
"Although there are many texts and monographs on fluid dynamics, I do not know of any which is as comprehensive as the present book. It surveys nearly the entire field of classical fluid dynamics in an advanced, compact, and clear manner, and discusses the various conceptual and analytical models of fluid flow." - Foundations of Physics on the first edition. Theoretical Fluid Dynamics functions equally well as a graduate-level text and a professional reference. Steering a middle course between the empiricism of engineering and the abstractions of pure mathematics, the author focuses
Directory of Open Access Journals (Sweden)
Yi Zhao
2017-01-01
Full Text Available The aim of this paper is to study the headway distribution of queued vehicles (less than 16 vehicles at signalized intersections. Existing studies usually take the average statistics of headway at any queuing place. When different percentile points of statistical data are assigned to headway, the passing rate (the rate of all queued vehicles passing the stop line under the ideal signal timing scheme varies. When selecting the mean value, the passing rate of a queue of fewer than 16 vehicles is no more than 65%. When selecting 75% as the percentile, the passing rate is up to 94%. The queue length also decides the assigned percentile of headway to ensure the passing rate reaches a certain level. The value assignation of headway directly affects lane capacity and start-up loss time. This paper provides a new perspective on parameter calibration and will make the signal timing algorithm method more effective.
Baër, Niek
2015-01-01
Traffic jams are everywhere, some are caused by constructions or accidents but a large portion occurs naturally. These "natural" traffic jams are a result of variable driving speeds combined with a high number of vehicles. To prevent these traffic jams, we must understand traffic in general, and to
Theoretical physics. Quantum mechanics
International Nuclear Information System (INIS)
Rebhan, Eckhard
2008-01-01
From the first in two comprehensive volumes appeared Theoretical Physics of the author by this after Mechanics and Electrodynamics also Quantum mechanics appears as thinner single volume. First the illustrative approach via wave mechanics is reproduced. The more abstract Hilbert-space formulation introduces the author later by postulates, which are because of the preceding wave mechanics sufficiently plausible. All concepts of quantum mechanics, which contradict often to the intuitive understanding formed by macroscopic experiences, are extensively discussed and made by means of many examples as well as problems - in the largest part provided with solutions - understandable. To the interpretation of quantum mechanics an extensive special chapter is dedicated. this book arose from courses on theoretical physics, which the author has held at the Heinrich-Heine University in Duesseldorf, and was in numerous repetitions fitted to the requirement of the studyings. it is so designed that it is also after the study suited as reference book or for the renewing. All problems are very thoroughly and such extensively studied that each step is separately reproducible. About motivation and good understandability is cared much
Dark matter: Theoretical perspectives
International Nuclear Information System (INIS)
Turner, M.S.
1993-01-01
The author both reviews and makes the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that (i) there are no dark-matter candidates within the open-quotes standard modelclose quotes of particle physics, (ii) there are several compelling candidates within attractive extensions of the standard model of particle physics, and (iii) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for open-quotes new physics.close quotes The compelling candidates are a very light axion (10 -6 --10 -4 eV), a light neutrino (20--90 eV), and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. The author briefly mentions more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos. 119 refs
Dark matter: Theoretical perspectives
Energy Technology Data Exchange (ETDEWEB)
Turner, M.S. (Chicago Univ., IL (United States). Enrico Fermi Inst. Fermi National Accelerator Lab., Batavia, IL (United States))
1993-01-01
I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for new physics.'' The compelling candidates are: a very light axion ( 10[sup [minus]6] eV--10[sup [minus]4] eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos.
Dark matter: Theoretical perspectives
Energy Technology Data Exchange (ETDEWEB)
Turner, M.S. [Chicago Univ., IL (United States). Enrico Fermi Inst.]|[Fermi National Accelerator Lab., Batavia, IL (United States)
1993-01-01
I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for ``new physics.`` The compelling candidates are: a very light axion ( 10{sup {minus}6} eV--10{sup {minus}4} eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos.
Near Theoretical Gigabit Link Efficiency for Distributed Data Acquisition Systems.
Abu-Nimeh, Faisal T; Choong, Woon-Seng
2017-03-01
Link efficiency, data integrity, and continuity for high-throughput and real-time systems is crucial. Most of these applications require specialized hardware and operating systems as well as extensive tuning in order to achieve high efficiency. Here, we present an implementation of gigabit Ethernet data streaming which can achieve 99.26% link efficiency while maintaining no packet losses. The design and implementation are built on OpenPET, an opensource data acquisition platform for nuclear medical imaging, where (a) a crate hosting multiple OpenPET detector boards uses a User Datagram Protocol over Internet Protocol (UDP/IP) Ethernet soft-core, that is capable of understanding PAUSE frames, to stream data out to a computer workstation; (b) the receiving computer uses Netmap to allow the processing software (i.e., user space), which is written in Python, to directly receive and manage the network card's ring buffers, bypassing the operating system kernel's networking stack; and (c) a multi-threaded application using synchronized queues is implemented in the processing software (Python) to free up the ring buffers as quickly as possible while preserving data integrity and flow continuity.
Theoretical Characterizaiton of Visual Signatures
Kashinski, D. O.; Chase, G. M.; di Nallo, O. E.; Scales, A. N.; Vanderley, D. L.; Byrd, E. F. C.
2015-05-01
We are investigating the accuracy of theoretical models used to predict the visible, ultraviolet, and infrared spectra, as well as other properties, of product materials ejected from the muzzle of currently fielded systems. Recent advances in solid propellants has made the management of muzzle signature (flash) a principle issue in weapons development across the calibers. A priori prediction of the electromagnetic spectra of formulations will allow researchers to tailor blends that yield desired signatures and determine spectrographic detection ranges. Quantum chemistry methods at various levels of sophistication have been employed to optimize molecular geometries, compute unscaled vibrational frequencies, and determine the optical spectra of specific gas-phase species. Electronic excitations are being computed using Time Dependent Density Functional Theory (TD-DFT). A full statistical analysis and reliability assessment of computational results is currently underway. A comparison of theoretical results to experimental values found in the literature is used to assess any affects of functional choice and basis set on calculation accuracy. The status of this work will be presented at the conference. Work supported by the ARL, DoD HPCMP, and USMA.
Theoretical physics 5 thermodynamics
Nolting, Wolfgang
2017-01-01
This concise textbook offers a clear and comprehensive introduction to thermodynamics, one of the core components of undergraduate physics courses. It follows on naturally from the previous volumes in this series, defining macroscopic variables, such as internal energy, entropy and pressure,together with thermodynamic principles. The first part of the book introduces the laws of thermodynamics and thermodynamic potentials. More complex themes are covered in the second part of the book, which describes phases and phase transitions in depth. Ideally suited to undergraduate students with some grounding in classical mechanics, the book is enhanced throughout with learning features such as boxed inserts and chapter summaries, with key mathematical derivations highlighted to aid understanding. The text is supported by numerous worked examples and end of chapter problem sets. About the Theoretical Physics series Translated from the renowned and highly successful German editions, the eight volumes of this series cove...
Theoretical physics 3 electrodynamics
Nolting, Wolfgang
2016-01-01
This textbook offers a clear and comprehensive introduction to electrodynamics, one of the core components of undergraduate physics courses. It follows on naturally from the previous volumes in this series. The first part of the book describes the interaction of electric charges and magnetic moments by introducing electro- and magnetostatics. The second part of the book establishes deeper understanding of electrodynamics with the Maxwell equations, quasistationary fields and electromagnetic fields. All sections are accompanied by a detailed introduction to the math needed. Ideally suited to undergraduate students with some grounding in classical and analytical mechanics, the book is enhanced throughout with learning features such as boxed inserts and chapter summaries, with key mathematical derivations highlighted to aid understanding. The text is supported by numerous worked examples and end of chapter problem sets. About the Theoretical Physics series Translated from the renowned and highly successful Germa...
Theoretical Particle Astrophysics
Energy Technology Data Exchange (ETDEWEB)
Kamionkowski, Marc [Johns Hopkins Univ., Baltimore, MD (United States)
2013-08-07
Abstract: Theoretical Particle Astrophysics. The research carried out under this grant encompassed work on the early Universe, dark matter, and dark energy. We developed CMB probes for primordial baryon inhomogeneities, primordial non-Gaussianity, cosmic birefringence, gravitational lensing by density perturbations and gravitational waves, and departures from statistical isotropy. We studied the detectability of wiggles in the inflation potential in string-inspired inflation models. We studied novel dark-matter candidates and their phenomenology. This work helped advance the DoE's Cosmic Frontier (and also Energy and Intensity Frontiers) by finding synergies between a variety of different experimental efforts, by developing new searches, science targets, and analyses for existing/forthcoming experiments, and by generating ideas for new next-generation experiments.
Theoretical Molecular Biophysics
Scherer, Philipp
2010-01-01
"Theoretical Molecular Biophysics" is an advanced study book for students, shortly before or after completing undergraduate studies, in physics, chemistry or biology. It provides the tools for an understanding of elementary processes in biology, such as photosynthesis on a molecular level. A basic knowledge in mechanics, electrostatics, quantum theory and statistical physics is desirable. The reader will be exposed to basic concepts in modern biophysics such as entropic forces, phase separation, potentials of mean force, proton and electron transfer, heterogeneous reactions coherent and incoherent energy transfer as well as molecular motors. Basic concepts such as phase transitions of biopolymers, electrostatics, protonation equilibria, ion transport, radiationless transitions as well as energy- and electron transfer are discussed within the frame of simple models.
CUSTOMER LOYALTY THEORETICAL ASPECTS
Margarita IŠORAITĖ
2016-01-01
Customer loyalty - is a voluntary user solution for a long time to build relationships with the company. Loyalty is the user's desire for a long time to continue their relationship with a particular company, because loyal customers are those who purchase goods/services of the company from time to time. Loyalty can be treated as a customer desire, willingness to be a regular customer for a long time, buying and using the goods of the chosen companies by recommending them to friends and colleag...
Online Self-Organizing Network Control with Time Averaged Weighted Throughput Objective
Directory of Open Access Journals (Sweden)
Zhicong Zhang
2018-01-01
Full Text Available We study an online multisource multisink queueing network control problem characterized with self-organizing network structure and self-organizing job routing. We decompose the self-organizing queueing network control problem into a series of interrelated Markov Decision Processes and construct a control decision model for them based on the coupled reinforcement learning (RL architecture. To maximize the mean time averaged weighted throughput of the jobs through the network, we propose a reinforcement learning algorithm with time averaged reward to deal with the control decision model and obtain a control policy integrating the jobs routing selection strategy and the jobs sequencing strategy. Computational experiments verify the learning ability and the effectiveness of the proposed reinforcement learning algorithm applied in the investigated self-organizing network control problem.
Managing truck arrivals with time windows to alleviate gate congestion at container terminals
DEFF Research Database (Denmark)
Chen, G.; Govindan, Kannan; Yang, Z.
2013-01-01
Long truck queues at gates often limit the efficiency of a container terminal and generate serious air pollution. To reduce the gate congestion, this paper proposes a method called'vessel dependent time windows (VDTWs)' to control truck arrivals, which involves partitioning truck entries into gro......Long truck queues at gates often limit the efficiency of a container terminal and generate serious air pollution. To reduce the gate congestion, this paper proposes a method called'vessel dependent time windows (VDTWs)' to control truck arrivals, which involves partitioning truck entries...... in the system. A conventional Genetic Algorithm (GA), a multi-society GA, and a hybrid algorithm using GA and Simulated Annealing are used to solve the optimization problem. A case study based on a real container terminal in China is performed, which shows the VDTWs method can flatten the truck arrivals...
Theoretical nuclear and subnuclear physics
Walecka, John Dirk
1995-01-01
This comprehensive text expertly details the numerous theoretical techniques central to the discipline of nuclear physics. It is based on lecture notes from a three-lecture series given at CEBAF (the Continuous Electron Beam Accelerator Facility), where John Dirk Walecka at the time was Scientific Director: "Graduate Quantum Mechanics", "Advanced Quantum Mechanics and Field Theory" and "Special Topics in Nuclear Physics". The primary goal of this text is pedagogical; providing a clear, logical, in-depth, and unifying treatment of many diverse aspects of modern nuclear theory ranging from the non-relativistic many-body problem to the standard model of the strong, electromagnetic, and weak interactions. Four key topics are emphasised in this text: basic nuclear structure, the relativistic nuclear many-body problem, strong-coupling QCD, and electroweak interactions with nuclei. The text is designed to provide graduate students with a basic level of understanding of modern nuclear physics so that they in turn can...
Strongly Correlated Systems Theoretical Methods
Avella, Adolfo
2012-01-01
The volume presents, for the very first time, an exhaustive collection of those modern theoretical methods specifically tailored for the analysis of Strongly Correlated Systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and materials science, belong to this class of systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognized main contributors. The exposition has a clear pedagogical cut and fully reports on the most relevant case study where the specific technique showed to be very successful in describing and enlightening the puzzling physics of a particular strongly correlated system. The book is intended for advanced graduate students and post-docs in the field as textbook and/or main reference, but also for other researchers in the field who appreciates consulting a single, but comprehensive, source or wishes to get acquainted, in a as painless as po...
Just-in-time connectivity for large spiking networks.
Lytton, William W; Omurtag, Ahmet; Neymotin, Samuel A; Hines, Michael L
2008-11-01
The scale of large neuronal network simulations is memory limited due to the need to store connectivity information: connectivity storage grows as the square of neuron number up to anatomically relevant limits. Using the NEURON simulator as a discrete-event simulator (no integration), we explored the consequences of avoiding the space costs of connectivity through regenerating connectivity parameters when needed: just in time after a presynaptic cell fires. We explored various strategies for automated generation of one or more of the basic static connectivity parameters: delays, postsynaptic cell identities, and weights, as well as run-time connectivity state: the event queue. Comparison of the JitCon implementation to NEURON's standard NetCon connectivity method showed substantial space savings, with associated run-time penalty. Although JitCon saved space by eliminating connectivity parameters, larger simulations were still memory limited due to growth of the synaptic event queue. We therefore designed a JitEvent algorithm that added items to the queue only when required: instead of alerting multiple postsynaptic cells, a spiking presynaptic cell posted a callback event at the shortest synaptic delay time. At the time of the callback, this same presynaptic cell directly notified the first postsynaptic cell and generated another self-callback for the next delay time. The JitEvent implementation yielded substantial additional time and space savings. We conclude that just-in-time strategies are necessary for very large network simulations but that a variety of alternative strategies should be considered whose optimality will depend on the characteristics of the simulation to be run.
Information Theoretic Shape Matching.
Hasanbelliu, Erion; Giraldo, Luis Sanchez; Príncipe, José C
2014-12-01
In this paper, we describe two related algorithms that provide both rigid and non-rigid point set registration with different computational complexity and accuracy. The first algorithm utilizes a nonlinear similarity measure known as correntropy. The measure combines second and high order moments in its decision statistic showing improvements especially in the presence of impulsive noise. The algorithm assumes that the correspondence between the point sets is known, which is determined with the surprise metric. The second algorithm mitigates the need to establish a correspondence by representing the point sets as probability density functions (PDF). The registration problem is then treated as a distribution alignment. The method utilizes the Cauchy-Schwarz divergence to measure the similarity/distance between the point sets and recover the spatial transformation function needed to register them. Both algorithms utilize information theoretic descriptors; however, correntropy works at the realizations level, whereas Cauchy-Schwarz divergence works at the PDF level. This allows correntropy to be less computationally expensive, and for correct correspondence, more accurate. The two algorithms are robust against noise and outliers and perform well under varying levels of distortion. They outperform several well-known and state-of-the-art methods for point set registration.
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.
CUSTOMER LOYALTY THEORETICAL ASPECTS
Directory of Open Access Journals (Sweden)
Margarita IŠORAITĖ
2016-08-01
Full Text Available Customer loyalty - is a voluntary user solution for a long time to build relationships with the company. Loyalty is the user's desire for a long time to continue their relationship with a particular company, because loyal customers are those who purchase goods/services of the company from time to time. Loyalty can be treated as a customer desire, willingness to be a regular customer for a long time, buying and using the goods of the chosen companies by recommending them to friends and colleagues. Loyalty can be seen as a multi-dimension, covering behavioral and positional components, where positional aspect reflects customers' approach to business, while the behavioral dimension reveals a frequent and regular shopping, purchase quantity, size, range, availability, etc.
Climate Change: a Theoretical Review
Directory of Open Access Journals (Sweden)
Muhammad Ishaq-ur Rahman
2013-01-01
Full Text Available Climate Change has been undoubtedly the most illustrious environmental issue since late 20th century. But neither the discourse merely emerged during that time, nor it was problematized in the same way since its onset. History of Climate Change discourse reveals that from a purely scientific concern it has turned into a public agenda that is nowadays more inclined to be development problem. Transformations have brought about a complete new paradigm every time. This article presents a theoretical analysis of the Climate Change discourse and to do so it captured the underlying philosophy of the issue using Thomas Kuhn’s well-known thesis of ‘paradigm shift’. In particular it discusses about the crisis that lead the issue towards transformations; explores key perspectives around the crisis thus representation of the issue in the environmental discourse over the time. While this paper establishes that with the beginning of the 21st century, the discourse entered into a new paradigm and will reach to a critical point by the end of 2012, it finally postulates some measures that the discourse might integrate with the existing to advance beyond that point.
Directory of Open Access Journals (Sweden)
Jian Zhang
2016-12-01
Full Text Available In the environment of intelligent transportation systems, traffic condition data would have higher resolution in time and space, which is especially valuable for managing the interrupted traffic at signalized intersections. There exist a lot of algorithms for offset tuning, but few of them take the advantage of modern traffic detection methods such as probe vehicle data. This study proposes a method using probe trajectory data to optimize and adjust offsets in real time. The critical point, representing the changing vehicle dynamics, is first defined as the basis of this approach. Using the critical points related to different states of traffic conditions, such as free flow, queue formation, and dissipation, various traffic status parameters can be estimated, including actual travel speed, queue dissipation rate, and standing queue length. The offset can then be adjusted on a cycle-by-cycle basis. The performance of this approach is evaluated using a simulation network. The results show that the trajectory-based approach can reduce travel time of the coordinated traffic flow when compared with using well-defined offline offset.
Methods for determining unimpeded aircraft taxiing time and evaluating airport taxiing performance
Directory of Open Access Journals (Sweden)
Yu Zhang
2017-04-01
Full Text Available The objective of this study is to improve the methods of determining unimpeded (nominal taxiing time, which is the reference time used for estimating taxiing delay, a widely accepted performance indicator of airport surface movement. After reviewing existing methods used widely by different air navigation service providers (ANSP, new methods relying on computer software and statistical tools, and econometrics regression models are proposed. Regression models are highly recommended because they require less detailed data and can serve the needs of general performance analysis of airport surface operations. The proposed econometrics model outperforms existing ones by introducing more explanatory variables, especially taking aircraft passing and over-passing into the considering of queue length calculation and including runway configuration, ground delay program, and weather factors. The length of the aircraft queue in the taxiway system and the interaction between queues are major contributors to long taxi-out times. The proposed method provides a consistent and more accurate method of calculating taxiing delay and it can be used for ATM-related performance analysis and international comparison.
Theoretical Division progress report
International Nuclear Information System (INIS)
Cooper, N.G.
1979-04-01
This report presents highlights of activities in the Theoretical (T) Division from October 1976-January 1979. The report is divided into three parts. Part I presents an overview of the Division: its unique function at the Los Alamos Scientific Laboratory (LASL) and within the scientific community as a whole; the organization of personnel; the main areas of research; and a survey of recent T-Division initiatives. This overview is followed by a survey of the 13 groups within the Division, their main responsibilities, interests, and expertise, consulting activities, and recent scientific accomplisments. The remainder of the report, Parts II and III, is devoted to articles on selected research activities. Recent efforts on topics of immediate interest to energy and weapons programs at LASL and elsewhere are described in Part II, Major National Programs. Separate articles present T-Divison contributions to weapons research, reactor safety and reactor physics research, fusion research, laser isotope separation, and other energy research. Each article is a compilation of independent projects within T Division, all related to but addressing different aspects of the major program. Part III is organized by subject discipline, and describes recent scientific advances of fundamental interest. An introduction, defining the scope and general nature of T-Division efforts within a given discipline, is followed by articles on the research topics selected. The reporting is done by the scientists involved in the research, and an attempt is made to communicate to a general audience. Some data are given incidentally; more technical presentations of the research accomplished may be found among the 47 pages of references. 110 figures, 5 tables
A theoretical framework of organizational change
Jacobs, G.; Polos, L.; van Witteloostuijn, A.; Christe-Zyse, J.
2013-01-01
Purpose – Organizational change is a risky endeavour. Most change initiatives fall short on their goals and produce high opportunity and process costs, which at times outweigh the content benefits of organizational change. This paper seeks to develop a framework, offering a theoretical toolbox to
Theoretical consideration and evaluation of thermal diffusivity ...
African Journals Online (AJOL)
The aim of this study was to theoretically consider and evaluate the transient temperature-time response of resin/ionomer materials between ~2EC (melting ice temperature) and ~50EC, and indicate their suitability as lining materials. Specimens of materials, cylindrical in geometry, (6 mm diameter and 10 mm in length), ...
Arnhajm's 'visual thinking': Theoretical (nonfoundation
Directory of Open Access Journals (Sweden)
Todorović Milorad V.
2012-01-01
Full Text Available In psychology, as in other sciences, surely there are concepts that are not theoretically based and are not consistently thought trough. One of these concepts that has found a significant place in the understanding of artistic creativity and psychology of art overall is Arnheim's term: 'visual perception'. It can be said, as Arnheim does, that any perception is thinking at the same time, all reasoning is also intuition, each observation invention, provided that this approach can be deduced from a psychological theory. Starting from Gestalt psychology that seems to be impossible. Understandably, Arnheim, as Gestalt psychologist, with this term wanted to point out that the whole is different than the sum of its parts. 'A visual thinking' was supposed to add something more to the perceptual experience, a property that the perception does not have. Since Gestalt psychology is not based on the psychic apparatus and deferred system, with different functions and especially those unconscious, it is difficult to talk about the theoretical grounding of this notion. Only after postulating these moments Arnheim could elaborate his view that the process of observing the world is interaction between the properties that certain object provides and observers nature. That 'nature of the observer' can only be viewed within the psychic apparatus. In the creativity (art and science, where it aims to be a basic explanatory principle, 'visual perception' is faced with difficulties such as statements from Goetea and Helmholtz, that what is important and new in their creation was given as a free forethought, and that their knowledge came as something almost complete.
A Place for Theoretical Inconsistency
Directory of Open Access Journals (Sweden)
Janet Newbury PhD Candidate
2011-12-01
Full Text Available The current article articulates how the expectation of theoretical consistency can be constraining for qualitative researchers. The author considers the origins of the tradition of theoretical consistency, and suggests that postmodern research - particularly that which focuses on social justice - might in fact be served by considering possibilities that emerge from multiple theoretical perspectives. To illustrate the application and contribution of theoretical inconsistency, three concrete examples of how these ideas have been applied within qualitative studies are discussed. By pragmatically drawing connections across theoretical differences, it is hoped that researchers will engage critically with their own theoretical commitments and assumptions, thus opening themselves up to new possibilities and to new and creative ways of coming together.
Photography and History: methodological and theoretical issues
Directory of Open Access Journals (Sweden)
Ivo Santos Canabarro
2015-06-01
Full Text Available This article discusses issues related to the relation of photography with the construction of historical knowledge, realizing the theoretical dimensions that encompass a whole field of study about photography. The use of photography with its theoretical and methodological support in history is very recent, as many historians only used it for writing text illustration. Our hypothesis is that photography can be an object and source of investigation and, at the same time, an object that offers notions of its use as a specific problem in the field of visual culture.
Theoretically Optimal Distributed Anomaly Detection
National Aeronautics and Space Administration — A novel general framework for distributed anomaly detection with theoretical performance guarantees is proposed. Our algorithmic approach combines existing anomaly...
The power of theoretical knowledge.
Alligood, Martha Raile
2011-10-01
Nursing theoretical knowledge has demonstrated powerful contributions to education, research, administration and professional practice for guiding nursing thought and action. That knowledge has shifted the primary focus of the nurse from nursing functions to the person. Theoretical views of the person raise new questions, create new approaches and instruments for nursing research, and expand nursing scholarship throughout the world.
Towards A Theoretical Biology: Reminiscences
Indian Academy of Sciences (India)
In 1967 I had decided to broaden my activities beyond the theoretical physics I had been engaged in since the start of my career at the University of Chicago. Theoretical biology was among the possibilities I was considering, though I then had no deep understanding of what it was and what it might become. Jack Cowan, a ...
Directory of Open Access Journals (Sweden)
Cheban Yuliia
2018-01-01
Full Text Available The right to leave is part of the employee’s legal status. It has every employee who works under an employment contract. Ensuring the employee’s right to leave is guaranteed by the state. At the same time, the term “vacation” is a significant range of different phenomena that have features in different sectors of the economy, including agrarian space, different regions, different production conditions, etc. The foregoing complicates not only the basic definition of the term “vacation”, but also its organizational and accounting support. According to the legislation of Ukraine, the holiday is set by law, collective agreement or employment contract a certain number of calendar days of continuous rest, which are provided to the employee by the employer in a calendar year, with or without payment, with the preservation of the place of work (position by the employee at this time. The citizens of Ukraine, who are in labor relations with enterprises, institutions, organizations irrespective of the forms of ownership, type of activity and branch affiliation, are also entitled to leave, as well as work under an employment contract from an individual. The main features that are inherent to the overwhelming majority of the holidays are the following: the employee’s dismissal from performing labor duties, the preservation of the employee during the period of vacations of the place of work (position, payment. Domestic legislation, together with the scientific achievements of researchers, the concept of “vacation” is identified with the concept of “time”. The main characteristic features of the vacation include the guarantee of vacation by law; scope of leave; periodicity of holidays; definition of the length of leave in legislation; continuity of rest during the holiday period; connection of vacation with work experience; the main purpose of vacation; preservation of the place of work at the time of vacations; saving at the time of
THEORETICAL ASPECTS OF SCHOOL TEXTBOOK
Directory of Open Access Journals (Sweden)
Sveriene, Audrone
2006-12-01
Full Text Available School textbook is an important part of general education. Some theoretical works were written on school textbook theory. The question about textbook concept, structure and functions wasunder the dispute a long time in Lithuania and abroad.The main purpose of this article is to analyse and summarize the experience of researchers school textbook theory from Lithuania and foreign countries. The tasks of article are to determineconcept of textbook, describe the structure and the functions of the textbook. Famous scientists in this field are D. Zujev (Russia, P. Weinbrenner, F. Pingel (Germany, J. Mikk (Estonia, E. B. Johnsen (Norway, A. Choppin (France, F. M. Gerard and X. Roegiers Belgium, R. Bamberger (Austria. There are many interpretations of textbook concept, and different suggestions what is a textbook. In Lithuania the textbook concept was discussed with some specialists of Educational Development Centre and the Ministry of Education and Science. The Requirements on textbook development were approved in Lithuania only in 2003. According to the research litterature, the main aspect of the textbook is to meet the requirements of curriculum. The textbook consists of text, paratext and illustrations. All these parts of the textbook play many functions in education. The main function of the textbook is to motivate students. Other important functions of the textbook are: information, systematisation, coordination, differentiation, guidance education, learning strategy, value education, aesthetical.
A Method of Signal Timing Optimization for Spillover Dissipation in Urban Street Networks
Directory of Open Access Journals (Sweden)
Dongfang Ma
2013-01-01
Full Text Available The precise identification and quick dissipation of spillovers are critically important in a traffic control system, especially when heavy congestion occurs. This paper first presents a calculation method for the occupancy per cycle under different traffic conditions and identifies the threshold of occupancy that characterizes the formation of spillovers. Then, capacity adjustments are determined for the incoming and outgoing streams of bottleneck links, with the aim of dissipating the queue to a permissible length within a given period of time, and optimization schemes are defined to calculate splits for the upstream and downstream intersections. Finally, taking average vehicular delay, outputs per cycle, and maximum queue length on the bottleneck link as the evaluation indices, the method of dissipating spillovers proposed in this paper is evaluated using a VISSIM simulation. The results show that the maximum queue length on the bottleneck link and the average vehicular delay at the upstream and downstream intersections decrease significantly under the new signal control plan; meanwhile, the new control schemes have little influence on the outputs of the two intersections per cycle.
Fayolle, Guy; Malyshev, Vadim
2017-01-01
This monograph aims to promote original mathematical methods to determine the invariant measure of two-dimensional random walks in domains with boundaries. Such processes arise in numerous applications and are of interest in several areas of mathematical research, such as Stochastic Networks, Analytic Combinatorics, and Quantum Physics. This second edition consists of two parts. Part I is a revised upgrade of the first edition (1999), with additional recent results on the group of a random walk. The theoretical approach given therein has been developed by the authors since the early 1970s. By using Complex Function Theory, Boundary Value Problems, Riemann Surfaces, and Galois Theory, completely new methods are proposed for solving functional equations of two complex variables, which can also be applied to characterize the Transient Behavior of the walks, as well as to find explicit solutions to the one-dimensional Quantum Three-Body Problem, or to tackle a new class of Integrable Systems. Part II borrows spec...
Theoretical Foundations of Learning Communities
Jessup-Anger, Jody E.
2015-01-01
This chapter describes the historical and contemporary theoretical underpinnings of learning communities and argues that there is a need for more complex models in conceptualizing and assessing their effectiveness.
Energy Technology Data Exchange (ETDEWEB)
Vahala, George M. [College of William and Mary, Williamsburg, VA (United States)
2013-12-31
with the electric field only being about three times higher than in the ideal case. Moreover, the quasi-optical grill was significantly fewer structural elements that the multijunction grill. Nevertheless there has not been much interest from experimental fusion groups to implementing these structures. Hence we have returned to optimizing the multijunction grill so that the large number of coupling matrix elements can be efficiently evaluated using symmetry arguments. In overdense plasmas, the standard electromagnetic waves cannot propagate into the plasma center, but are reflected at the plasma edge. By optimizing mode conversion processes (in particular, the O-X-B wave propagation of Ordinary Mode converting to an Extraordinary mode which then converts into an electrostatic Bernstein wave) one can excite within the plasma an electrostatic Bernstein wave that does not suffer density cutoffs and is absorbed on the electron cyclotron harmonics. Finally we have started looking at other mesoscopic lattice algorithms that involve unitary collision and streaming steps. Because these algorithms are unitary they can be run on quantum computers when they become available – unlike their computational cousin of lattice Boltzmann which is a purely classical code. These quantum lattice gas algorithms have been tested successfully on exact analytic soliton collision solution. These calculations are hoped to be able to study Bose Einstein condensed atomic gases and their ground states in an optical lattice.
Theoretical aspectsof labour evaluation effectiveness
Ivanov, M.
2014-01-01
The article deals with determination of the benchmark for building a system of payment and financial incentives in the agricultural sector. The author theoretically justifies the need for such a measure as a category of “labor efficiency” and gives a theoretical rationale for the use of this category. A method for calculating performance indicators of labor using the coefficients of the quality of work is offered in this article.
Franchise Business Model: Theoretical Insights
Levickaitė, Rasa; Reimeris, Ramojus
2010-01-01
The article is based on literature review, theoretical insights, and deals with the topic of franchise business model. The objective of the paper is to analyse peculiarities of franchise business model and its developing conditions in Lithuania. The aim of the paper is to make an overview on franchise business model and its environment in Lithuanian business context. The overview is based on international and local theoretical insights. In terms of practical meaning, this article should be re...
Bariatric surgery waiting times in Canada.
Christou, Nicolas V; Efthimiou, Evangelos
2009-06-01
Severe obesity is reaching epidemic proportions throughout the world, including Canada. The only permanent treatment of severe or morbid obesity is bariatric surgery. Access to bariatric surgery is very limited in Canada. We sought to collect accurate data on waiting times for the procedure. We carried out a survey of members of the Canadian Association of Bariatric Physicians and Surgeons and performed a more detailed analysis within Quebec and at one Canadian bariatric surgery centre where a prospectively collected bariatric surgery registry has been maintained since 1983. The survey response rate was 85%. All centres determined whether patients were eligible for bariatric surgery based on the National Institutes of Health criteria. Patients entered the queue as "office contacts" and moved through the queue, with the exit point being completion of the procedure. In 2007, a total of 6783 patients were waiting for bariatric surgery and 1313 procedures were performed in Canada. Assuming these trends are maintained, the calculated average waiting time for bariatric surgery in Canada is just over 5 years (6783/1313). The Fraser Institute and the Wait Times Alliance benchmarks for reasonable surgical waiting times vary from 8 weeks for cancer surgery to 18 months for cosmetic surgery. At one Canadian centre, 12 patients died while waiting for bariatric surgery. The waiting times for bariatric surgery are the longest of any surgically treated condition. Given the significant reduction in the relative risk of death with bariatric surgery (40%-89% depending on the study), the current waiting times for the procedure in Canada are unacceptable.
Department of Theoretical Physics - Overview
International Nuclear Information System (INIS)
Kwiecinski, J.
2001-01-01
Full text: Research activity of the Department of Theoretical Physics concerns theoretical high-energy and elementary particle physics, intermediate energy particle physics, theoretical nuclear physics, theory of nuclear matter, theory of quark-gluon plasma and relativistic heavy-ion collisions, theoretical astrophysics and general physics. There is some emphasis on the phenomenological applications of the theoretical research yet more formal problems are also considered. A detailed summary of the research projects and of the results obtained in various field is given in the abstracts. Our Department actively collaborates with other Departments of the Institute as well as with several scientific institutions both in Poland and abroad. In particular, members of our Department participate in the EC network, which stimulates the mobility of researchers. Several members of our Department also participated in the research projects funded by the Polish Committee for Scientific Research (KBN). Besides pure research, members of our Department are also involved in graduate and up graduate teaching activity at our Institute as well as at other academic institution in Cracow. At present nine students are working on their Ph.D. degrees under the supervision of senior members of the Department. (author)
Department of Theoretical Physics - Overview
International Nuclear Information System (INIS)
Kwiecinski, J.
2002-01-01
Full text: Research activity of the Department of Theoretical Physics concerns theoretical high energy and elementary particle physics, intermediate energy particle physics, theoretical nuclear physics, theory of nuclear matter, theory of quark-gluon plasma and of relativistic heavy ion collisions, theoretical astrophysics and general physics. There is some emphasis on the phenomenological applications of the theoretical research yet the more formal problems are also considered. The detailed summary of the research projects and of the results obtained in various fields is given in the abstracts. Our Department successfully collaborates with other Departments of the Institute as well as with several scientific institutions both in Poland and abroad. In particular, members of our Department participate in the EC network which allows for the mobility of researchers. Several members of our Department have also participated in the research projects funded by the State Committee for Scientific Research. Besides pure research, members of our Department are also involved in graduate and undergraduate teaching activity both at our Institute and at other academic institutions in Cracow. At present, eight students are working towards their Ph.D. degrees under the supervision of senior members of the Department. (author)
Department of Theoretical Physics - Overview
International Nuclear Information System (INIS)
Kwiecinski, J.
2000-01-01
Full text: Research activity of the Department of Theoretical Physics concerns theoretical high-energy and elementary particle physics, intermediate energy particle physics, theoretical nuclear physics, theory of nuclear matter, theory of quark-gluon plasma and of relativistic heavy-ion collisions, theoretical astrophysics and general physics. There is some emphasis on the phenomenological applications of the theoretical research, yet the more formal problems are also considered. The detailed summary of the research projects and of the results obtained in various fields is given in the abstracts. Our Department actively collaborates with other Departments of the Institute as well as with several scientific institutions both in Poland and abroad. In particular members of our Department participate in the EC network which allows mobility of researchers. Several members of our Department have also participated in the research projects funded by the Polish Committee for Scientific Research (KBN). The complete list of grants is listed separately. Besides pure research, members of our Department are also involved in graduate and undergraduate teaching activity both at our Institute as well as at other academic institutions in Cracow. At present five students are working for their Ph.D. or MSc degrees under supervision of the senior members from the Department. We continue our participation at the EC SOCRATES-ERASMUS educational programme which allows exchange of graduate students between our Department and the Department of Physics of the University of Durham in the UK. (author)
Theoretical behaviorism meets embodied cognition : Two theoretical analyses of behavior
Keijzer, F.A.
2005-01-01
This paper aims to do three things: First, to provide a review of John Staddon's book Adaptive dynamics: The theoretical analysis of behavior. Second, to compare Staddon's behaviorist view with current ideas on embodied cognition. Third, to use this comparison to explicate some outlines for a
A unified grand tour of theoretical physics
Lawrie, Ian D
2013-01-01
A Unified Grand Tour of Theoretical Physics invites its readers to a guided exploration of the theoretical ideas that shape our contemporary understanding of the physical world at the fundamental level. Its central themes, comprising space-time geometry and the general relativistic account of gravity, quantum field theory and the gauge theories of fundamental forces, and statistical mechanics and the theory of phase transitions, are developed in explicit mathematical detail, with an emphasis on conceptual understanding. Straightforward treatments of the standard models of particle physics and cosmology are supplemented with introductory accounts of more speculative theories, including supersymmetry and string theory. This third edition of the Tour includes a new chapter on quantum gravity, focusing on the approach known as Loop Quantum Gravity, while new sections provide extended discussions of topics that have become prominent in recent years, such as the Higgs boson, massive neutrinos, cosmological perturba...
Theoretical aspects of spatial-temporal modeling
Matsui, Tomoko
2015-01-01
This book provides a modern introductory tutorial on specialized theoretical aspects of spatial and temporal modeling. The areas covered involve a range of topics which reflect the diversity of this domain of research across a number of quantitative disciplines. For instance, the first chapter provides up-to-date coverage of particle association measures that underpin the theoretical properties of recently developed random set methods in space and time otherwise known as the class of probability hypothesis density framework (PHD filters). The second chapter gives an overview of recent advances in Monte Carlo methods for Bayesian filtering in high-dimensional spaces. In particular, the chapter explains how one may extend classical sequential Monte Carlo methods for filtering and static inference problems to high dimensions and big-data applications. The third chapter presents an overview of generalized families of processes that extend the class of Gaussian process models to heavy-tailed families known as alph...
A sign-theoretic approach to biotechnology
DEFF Research Database (Denmark)
Bruni, Luis Emilio
to exemplify what is the relevance of a sign-theoretic approach to biotechnology. In particular, I introduce the notion of digital-analogical consensus as a semiotic pattern for the creation of complex logical products that constitute specific signs. The chapter ends with some examples of conspicuous semiotic......, translation, transformation and transmission of information. The idea is also to investigate how this debate may influence the “integrative agenda” in biology, especially at a time in which biotechnology is considered to be the industrial use of “biological information”. I introduce concepts....... Finally I make a connection between a sign-theoretic approach to biotechnology and sustainability, with a glimpse into the future....
Topics in modern physics theoretical foundations
Walecka, John Dirk
2013-01-01
While the two previous books entitled Introduction to Modern Physics: Theoretical Foundations and Advanced Modern Physics: Theoretical Foundations exposed the reader to the foundations and frontiers of today's physics, the goal of this third volume is to cover in some detail several topics omitted in the essentially linear progression of the first two. This book is divided into three parts. Part 1 is on quantum mechanics. Analytic solutions to the Schrödinger equation are developed for some basic systems. The analysis is then formalized, concluding with a set of postulates for the theory. Part 2 is on applications of quantum mechanics: approximation methods for bound states, scattering theory, time-dependent perturbation theory, and electromagnetic radiation and quantum electrodynamics. Part 3 covers some selected topics in relativistic quantum field theory: discrete symmetries, the Heisenberg picture, and the Feynman rules for quantum chromodynamics. The three volumes in this series taken together provide ...
Mechanics lectures on theoretical physics
Sommerfeld, Arnold Johannes Wilhelm
1952-01-01
Mechanics: Lectures on Theoretical Physics, Volume I covers a general course on theoretical physics. The book discusses the mechanics of a particle; the mechanics of systems; the principle of virtual work; and d'alembert's principle. The text also describes oscillation problems; the kinematics, statics, and dynamics of a rigid body; the theory of relative motion; and the integral variational principles of mechanics. Lagrange's equations for generalized coordinates and the theory of Hamilton are also considered. Physicists, mathematicians, and students taking Physics courses will find the book
Theoretical chemistry advances and perspectives
Eyring, Henry
1977-01-01
Theoretical Chemistry: Advances and Perspectives, Volume 2 covers all aspects of theoretical chemistry.This book reviews the techniques that have been proven successful in the study of interatomic potentials in order to describe the interactions between complex molecules. The ground state properties of the interacting electron gas when a magnetic field is present are also elaborated, followed by a discussion on the Gellman-Brueckner-Macke theory of the correlation energy that has applications in atomic and molecular systems.This volume considers the instability of the Hartree-Fock ground state
Theoretical Framework for Robustness Evaluation
DEFF Research Database (Denmark)
Sørensen, John Dalsgaard
2011-01-01
This paper presents a theoretical framework for evaluation of robustness of structural systems, incl. bridges and buildings. Typically modern structural design codes require that ‘the consequence of damages to structures should not be disproportional to the causes of the damages’. However, although...... the importance of robustness for structural design is widely recognized the code requirements are not specified in detail, which makes the practical use difficult. This paper describes a theoretical and risk based framework to form the basis for quantification of robustness and for pre-normative guidelines...
Theoretical mechanics for sixth forms
Plumpton, C
1971-01-01
Theoretical Mechanics for Sixth Forms, Second Edition is a 14-chapter book that begins by elucidating the nature of theoretical mechanics. The book then describes the statics of a particle in illustration of the techniques of handling vector quantities. Subsequent chapters focus on the principle of moments, parallel forces and centers of gravity; and the application of Newton's second law to the dynamics of a particle and the ideas of work and energy, impulse and momentum, and power. The concept of friction is also explained. This volume concludes with chapters concerning motion in a circle an
Performance Analysis of Statistical Time Division Multiplexing Systems
Directory of Open Access Journals (Sweden)
Johnson A. AJIBOYE
2010-12-01
Full Text Available Multiplexing is a way of accommodating many input sources of a low capacity over a high capacity outgoing channel. Statistical Time Division Multiplexing (STDM is a technique that allows the number of users to be multiplexed over the channel more than the channel can afford. The STDM normally exploits unused time slots by the non-active users and allocates those slots for the active users. Therefore, STDM is appropriate for bursty sources. In this way STDM normally utilizes channel bandwidth better than traditional Time Division Multiplexing (TDM. In this work, the statistical multiplexer is viewed as M/M/1queuing system and the performance is measured by comparing analytical results to simulation results using Matlab. The index used to determine the performance of the statistical multiplexer is the number of packets both in the system and the queue. Comparison of analytical results was also done between M/M/1 and M/M/2 and also between M/M/1 and M/D/1 queue systems. At high utilizations, M/M/2 performs better than M/M/1. M/D/1 also outperforms M/M1.
Teaching Theoretical Criminology to Undergraduates.
Williams, James L.; And Others
1995-01-01
Maintains that U.S. society's emphasis on individuality and pragmatism renders theoretical study of criminal deviance difficult for many students. Presents a structured approach to this problem that includes an emphasis on practical applications, comparative analysis, analytical skills, and the substantive content of theories. Describes teaching…
Refresher Course in Theoretical Physics
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 7. Refresher Course in Theoretical Physics. Information and Announcements Volume 6 Issue 7 July 2001 pp 99-99. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/006/07/0099-0099. Resonance ...
Tau decays: A theoretical perspective
International Nuclear Information System (INIS)
Marciano, W.J.
1992-11-01
Theoretical predictions for various tau decay rates are reviewed. Effects of electroweak radiative corrections are described. Implications for precision tests of the standard model and ''new physics'' searches are discussed. A perspective on the tau decay puzzle and 1-prong problem is given
THEORETICAL INVESTIGATION OF STRESSES DISTRIBUTIONS ...
African Journals Online (AJOL)
The relationship between cavity size and number on one hand and combinations of web thicknesses were investigated theoretically. The least number of cavities was 4 for end-web to centre web ratio of 1:2 at constant shell thickness with the least web thickness equal to 12.5mm. The effects of the number of cavities and ...
Theoretical Framework. The Bartlesville System.
Roberts, Tommy L.; And Others
The theoretical framework underlying the Total Guidance Information Support System is discussed under the following topics: (1) Review of Literature, (2) A Brief History of Guidance and Counseling, (3) Philosophies of Guidance, (4) Decision-Making in Relation to Guidance, (5) The Origins of Information Theory, (6) Various Uses of Information…
Theoretical models of DNA flexibility
Czech Academy of Sciences Publication Activity Database
Dršata, Tomáš; Lankaš, Filip
2013-01-01
Roč. 3, č. 4 (2013), s. 355-363 ISSN 1759-0876 Institutional support: RVO:61388963 Keywords : molecular dynamics simulations * base pair level * indirect readout Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 9.041, year: 2013
Theoretical analysis of rolled joints
International Nuclear Information System (INIS)
Sinha, R.K.
1975-01-01
A procedure for theoretically analysing the case of an externally restrained sandwich joint formed by a hypothetical uniform hydrostatic expansion process is outlined. Reference is made to a computer program based on this theory. Results illustrating the effect of major joint variables on residual contact pressure are presented and analysed. The applicability and limitations of this theory are discussed. (author)
Theoretical Linguistics And Multilingualism Research
African Journals Online (AJOL)
KATEVG
Abstract. This paper tries to construct a bridge between the concerns of theoretical linguistics and those of multilingualism and code-switching (CS) research. It argues that the primary special point of interaction between these fields lies in the question of potential equivalence between elements or categories, bridging across ...
Theoretical Issues in Environmental Psychology
Proshansky, Harold M.
1974-01-01
Author addressed a central task in the development of an interdisciplinary field of inquiry into manenvironment relations: namely, theory development. He decried the lack of comprehensive theoretical reasoning that has characterized environmental research and suggested directions for expanded conceptual work. (Editor/RK)
Lightning Talks 2015: Theoretical Division
Energy Technology Data Exchange (ETDEWEB)
Shlachter, Jack S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-11-25
This document is a compilation of slides from a number of student presentations given to LANL Theoretical Division members. The subjects cover the range of activities of the Division, including plasma physics, environmental issues, materials research, bacterial resistance to antibiotics, and computational methods.
Theoretical Considerations of Peer Tutoring.
Cohen, Jiska
1986-01-01
Addresses the need for a theoretical analysis of the peer tutoring process by discussing: definitions of the process, the psychological and educational processes in peer tutoring as a learning and teaching experience, and the conceptualization of peer tutoring as a cooperative social system and a group reward structure. (Author/ABB)
Infantilism: Theoretical Construct and Operationalization
Sabelnikova, Y. V.; Khmeleva, N. L.
2018-01-01
The aim of this article is to define and operationalize the construct of infantilism. The methods of theoretical research involve analysis and synthesis. Age and content criteria are analyzed for childhood and adulthood. Infantile traits in an adult are described. Results: The characteristics of adult infantilism in the modern world are defined,…