Queue lines are a fundamental inevitably of the modern theme park. Parks have begun to introduce various systems for combating the normal queue, some of which are at no extra cost to guests and some of which are an extra cost. These systems feature a variety of methods by which guests can bypass the normal queue and enter one featuring a minimal wait. Parks have also started to introduce elements within queues that make waiting in them easier and change guests’ perception of time, thus making the waits seem shorter. This thesis attempts to determine the attitudes of guests towards these new trends as well as traditional queuing. Experiences and perceptions of queues from theme park guests were collected and have been compared with existing literature on guest satisfaction, theme parks and queue lines in order to determine relationships between current practices and theory. The findings from these relationships resulted in several suggestions for theme parks to take into account as queues continue to evolve in order to best suit guest needs.

Walking is the oldest and foremost mode of transportation through history and the prevalence of walking has increased. Effective pedestrian model is crucial to evaluate pedestrian facility service level and to enhance pedestrian safety, performance, and satisfaction. The objectives of this study were to: (1) validate the efficacy of utilizing queueing network model, which predicts cognitive information processing time and task performance; (2) develop a generalized queueing network based cognitive information processing model that can be utilized and applied to construct pedestrian cognitive structure and estimate the reaction time with the first moment of service time distribution; (3) investigate pedestrian behavior through naturalistic and experimental observations to analyze the effects of environment settings and psychological factors in pedestrians; and (4) develop pedestrian level of service (LOS) metrics that are quick and practical to identify improvement points in pedestrian facility design. Two empirical and two analytical studies were conducted to address the research objectives. The first study investigated the efficacy of utilizing queueing network in modeling and predicting the cognitive information processing time. Motion capture system was utilized to collect detailed pedestrian movement. The predicted reaction time using queueing network was compared with the results from the empirical study to validate the performance of the model. No significant difference between model and empirical results was found with respect to mean reaction time. The second study endeavored to develop a generalized queueing network system so the task can be modeled with the approximated queueing network and its first moment of any service time distribution. There was no significant difference between empirical study results and the proposed model with respect to mean reaction time. Third study investigated methods to quantify pedestrian traffic behavior, and analyze physical and cognitive behavior from the real-world observation and field experiment. Footage from indoor and outdoor corridor was used to quantify pedestrian behavior. Effects of environmental setting and/or psychological factor on travel performance were tested. Finally, adhoc and tailor-made LOS metrics were presented for simple realistic service level assessments. The proposed methodologies were composed of space revision LOS, delay-based LOS, preferred walking speed-based LOS, and ‘blocking probability’.

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No description available.

<p>We study the server allocation problem for tandem queues in the absence of intermediate buffer space. Servers are assumed to be homogeneous and non-collaborative. We provide policies to maximize the throughput. We break down our work into four stages. First, we assume that all servers are dedicated. We propose an allocation algorithm that assigns servers to stations based on the mean service times and the current number of servers assigned to each station. The algorithm is proposed for stations with exponentially distributed service times, but where the service rate at each station may be different. We further study the impact on the proposed allocation method of including service time distributions with different coecients of variation. Second, we consider tandem queues with both dedicated and flexible servers. We examine policies to dynamically assign flexible servers. When there is one flexible server and two stations each with a dedicated server, we completely characterize the optimal policy. We use the insights gained from applying the Policy Iteration algorithm on systems with three, four, and five stations to devise heuristics for systems of arbitrary size. Third, we study cases where flexibility is constrained such that flexible servers can only service two adjacent stations. We provide optimal policies for tandem queues with three and four stations and compare them with optimal policies for corresponding non-constrained cases. Fourth, we consider two parallel tandem queues with both dedicated servers and vertical flexible servers - servers that can move between corresponding stations of the two tandem queues. The workload allocations are the same for each line and each vertical flexible server moves only between two corresponding stations. We examine policies for dynamic allocation of these vertical flexible servers. When each tandem queue has two stations, each station possesses a dedicated server, and a vertical flexible server exists for each pair of stations, we specify the optimal policy. For cases with more than two stations, heuristic assignments are proposed. We also analyze the throughput improvement gained from adding flexible servers within a tandem queue or between two parallel tandem queues. Numerical results are used to verify the heuristics provided in each of the stages.</p> / Doctor of Philosophy (PhD)

Les files d'attente fluides sont des processus markoviens à deux dimensions, où la première composante, appelée le niveau, représente le contenu d'un réservoir et prend des valeurs continues, et la deuxième composante, appelée la phase, est l'état d'un processus markovien dont l'évolution contrôle celle du niveau. Le niveau de la file fluide varie linéairement avec un taux qui dépend de la phase et qui peut prendre n'importe quelle valeur réelle. Dans cette thèse, nous explorons le lien entre les files fluides et les processus QBD, et nous appliquons des arguments utilisés en théorie des processus de renouvellement pour obtenir la distribution stationnaire de plusieurs modèles fluides. Nous commençons par l'étude d'une file fluide avec un réservoir de taille infinie; nous déterminons sa distribution stationnaire, et nous présentons un algorithme permettant de calculer cette distribution de manière très efficace. Nous observons que la distribution stationnaire de la file fluide de capacité infinie est très semblable à celle d'un processus QBD avec une infinité de niveaux. Nous poursuivons la recherche des similarités entre les files fluides et les processus QBD, et nous étudions ensuite la distribution stationnaire d'une file fluide de capacité finie. Nous montrons que l'algorithme valable pour le cas du réservoir infini permet de calculer toutes les quantités importantes du modèle avec un réservoir fini. Nous considérons ensuite des modèles fluides plus complexes, de capacité finie ou infinie, où le comportement du processus markovien des phases peut changer lorsque le niveau du réservoir atteint certaines valeurs seuils. Nous montrons que les méthodes développées pour des modèles classiques s'étendent de manière naturelle à ces modèles plus complexes. Pour terminer, nous étudions les conditions nécessaires et suffisantes qui mènent à l'indépendance du niveau et de la phase d'une file fluide de capacité infinie en régime stationnaire. Ces résultats s'appuient sur des résultats semblables concernant des processus QBD. Markov modulated fluid queues are two-dimensional Markov processes, of which the first component, called the level, represents the content of a buffer or reservoir and takes real values; the second component, called the phase, is the state of a Markov process which controls the evolution of the level in the following manner: the level varies linearly at a rate which depends on the phase and which can take any real value. In this thesis, we explore the link between fluid queues and Quasi Birth-and-Death (QBD) processes, and we apply Markov renewal techniques in order to derive the stationary distribution of various fluid models. To begin with, we study a fluid queue with an infinite capacity buffer; we determine its stationary distribution and we present an algorithm which performs very efficiently in the determination of this distribution. We observe that the equilibrium distribution of the fluid queue is very similar to that of a QBD process with infinitely many levels. We further exploit the similarity between the two processes, and we determine the stationary distribution of a finite capacity fluid queue. We show that the algorithm available in the infinite case allows for the computation of all the important quantities entering in the expression of this distribution. We then consider more complex models, of either finite or infinite capacities, in which the behaviour ff the phase process may change whenever the buffer is empty or full, or when it reaches certain thresholds. We show that the techniques that we develop for the simpler models can be extended quite naturally in this context. Finally, we study the necessary and sufficient conditions that lead to the independence between the level and the phase of an infinite capacity fluid queue in the stationary regime. These results are based on similar developments for QBD processes.

Made available in DSpace on 2016-08-10T10:40:33Z (GMT). No. of bitstreams: 1 ALAN FERREIRA DA ENCARNACAO.pdf: 2933331 bytes, checksum: c35f4b9fb1427d754df19f35454d444e (MD5) Previous issue date: 2015-08-18 / This paper discusses the application of discrete simulation for the management of queues in the service sector. Some service providers do not correctly dimensioning its service capacity generating queues. The efficient management of queues assists managers in making decisions. The characteristics of services and their important activities are addressed, aiming to demonstrate the Computational Simulation utility to find a balance that satisfies the customer and is economically viable for the service manager. The study object is a self-service restaurant. Through the Software ARENA was developed a model of discrete type and stochastic to play everyday restaurant setting. It concludes that the discrete simulation software has modeling elements that meets the application requirements. The studied restaurant has different characteristics from traditional self-service with layout in series, and it was necessary to provide the model a route for the flow of customers. The study concluded that the queues occur in the mass preparation process, special meat preparation and boxes, with average waiting times of up to 5 minutes. In the other processes, which are trim service, salad - dessert, scale and location of a table - chair is available, the queues have a very agile flow. The operating model obtained allowed the evaluation of some scenarios aiming to reduce the queue time. / Este trabalho discute a aplicação da simulação discreta para a gestão de filas no setor de serviços. Alguns prestadores de serviços não dimensionam corretamente sua capacidade de atendimento gerando assim as filas. A gestão eficiente das filas auxilia os gestores na tomada de decisões. São abordadas as características das atividades de serviços e sua importância, tendo como objetivo demonstrar a utilidade da Simulação Computacional para se encontrar um ponto de equilíbrio que satisfaça o cliente e seja viável economicamente para o gestor do serviço. O objeto de estudo é um restaurante selfservice. Através do Software ARENA foi desenvolvido um modelo do tipo discreto e estocástico para reproduzir o ambiente diário do Restaurante. Conclui-se que o software de simulação discreta possui elementos de modelagem que atende as necessidades da aplicação. O restaurante estudado possui características diferentes do tradicional selfservice com layout em série, e foi necessário prever no modelo um roteamento para o fluxo de clientes. O estudo concluiu que as filas ocorrem nos processos de preparo de massas, preparo de carnes especiais e caixas, com tempos médios de espera de até 5min. Nos demais processos, que são serviço de guarnição, salada-sobremesa, balança e localização de uma mesa-com cadeira disponível, as filas possuem um fluxo bem ágil. O modelo operacional obtido permitiu a avaliação de alguns cenários visando diminuição do tempo de fila.

<p>In this project we illustrate how queueing simulation may be used to find the optimal interval for checkpointing problems and compare results with theoretical computations for simple systems that may be treated analytically.</p><p>We consider a relatively simple model for an internet banking facility. From time to time, the application server breaks down. The information at the time of the breakdown has to be passed onto the back up server before service may be resumed. To make the change over as efficient as possible, information of the state of user’s accounts is saved at regular intervals. This is known as checkpointing.</p><p>Firstly, we use GPSS (a queueing simulation tool) to find, by simulation, an optimal checkpointing interval, which maximises the efficiency of the server. Two measures of efficiency are considered; the availability of the server and the average time a customer spends in the system. Secondly, we investigate how far the queueing theory can go to providing an analytic solution to the problem and see whether or not this is in line with the results obtained through simulation.</p><p>The analysis shows that checkpointing is not necessary if breakdowns occur frequently and log reading after failure does not take much time. Otherwise, checkpointing is necessary and the analysis shows how GPSS may be used to obtain the optimal checkpointing interval. Relatively complicated systems may be simulated, where there are no analytic tools available. In simple cases, where theoretical methods may be used, the results from our simulations correspond with the theoretical calculations.</p>

In this project we illustrate how queueing simulation may be used to find the optimal interval for checkpointing problems and compare results with theoretical computations for simple systems that may be treated analytically. We consider a relatively simple model for an internet banking facility. From time to time, the application server breaks down. The information at the time of the breakdown has to be passed onto the back up server before service may be resumed. To make the change over as efficient as possible, information of the state of user’s accounts is saved at regular intervals. This is known as checkpointing. Firstly, we use GPSS (a queueing simulation tool) to find, by simulation, an optimal checkpointing interval, which maximises the efficiency of the server. Two measures of efficiency are considered; the availability of the server and the average time a customer spends in the system. Secondly, we investigate how far the queueing theory can go to providing an analytic solution to the problem and see whether or not this is in line with the results obtained through simulation. The analysis shows that checkpointing is not necessary if breakdowns occur frequently and log reading after failure does not take much time. Otherwise, checkpointing is necessary and the analysis shows how GPSS may be used to obtain the optimal checkpointing interval. Relatively complicated systems may be simulated, where there are no analytic tools available. In simple cases, where theoretical methods may be used, the results from our simulations correspond with the theoretical calculations.

Consider two Markovian N-policy queueing models in discrete time, one with batch arrival, the other with batch service. In this paper the transient behaviour of both models is studied and the analogous continuous time results are achieved by a limiting process. The steady state solution for the model with batch arrival is derived. (author's abstract) / Series: Forschungsberichte / Institut für Statistik