[pt] Cada vez mais os aparelhos móveis estão se aperfeiçoando, com aumentos em suas capacidades de processamento e memória. Essa tendência acaba tornando o processamento móvel uma alternativa interessante. Este trabalho visa explorar esse mundo mobile e o seu potencial através do paralelismo, tanto localmente, na forma de exploração multicore, quanto distribuida, na forma de exploração multidispositivo. Exploramos isto através de uma biblioteca de paralelismo da linguagem de programação Lua, chamada Luaproc. Propomos um novo modelo de comunicação para esta biblioteca, para incluir esse cenário multidispositivo e combinar as facilidades de um serviço de enfileiramento de mensagens com o suporte para paralelismo já existente. Apresentamos algumas aplicações da biblioteca desenvolvida, avaliando sua utilização e desempenho em diferentes cenários. / [en] Mobile devices are undergoing constant increases in their processing and memory capabilities. This tendency is making mobile processing an interesting alternative. This work aims to support the programmer in exploring this potential by using parallelism, both local, in the form of multicore exploitation, as well as distributed, in the form of multidevice exploration. We explored this through a parallel library for the Lua programming language, called Luaproc. We propose an extension to this library and its communication model, to include this multidevice scenario and combine the facilities of a message queuing service with the existing facilities for multicore programming. We then present some applications to show different use cases with distribution and their performance.

Orientador: Marina Vachkovskaia / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-21T12:11:37Z (GMT). No. of bitstreams: 1 Oliveira_HeloisaMariade_D.pdf: 1371327 bytes, checksum: 1913d92f9ff81812cfbf5b4fab73215d (MD5) Previous issue date: 2012 / Resumo: Considere as redes de filas com N servidores e K tipos de trabalho. Suponha que os tipos de trabalho i chegam independentemente à rede de acordo com o processo de Poisson com taxa...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: Consider a queueing network with N servers and K types of jobs (or customer classes). The types of jobs i, i = 1; ¿ ;K, arrive at the system accordingly to independent Poisson process with rate...Note: The complete abstract is available with the full electronic document / Doutorado / Estatistica / Doutora em Estatística

(i) The thesis sets out to address the problematic phenomenon of Systems of Congestion via Basic Queueing Theory. The theory, and its application in practice, appears to be a field of study which is the common domain of “theorists” and “practitioners”. (ii) This professional dichotomy has come about due to diverging interests in that one group is mainly interested in the purity of mathematical modelling, and the other group is motivated to use modelling, which conveniently employs applications oriented solutions. (iii) The schism between the groups has been accentuated by the “practitioners” who in addition to having an interest in steady state system behaviour make use of methods of modelling of the transient operation of complex Systems of Congestion. (iv) At the outset the thesis demonstrates how closed form solutions are obtained for steady state and transient state operation of a selection of Systems of Congestion. The attendant mathematical derivations are elegant and intricate. (v) Having revealed the limited utility of closed-form solutions the thesis proceeds to investigate the feasibility of using dynamical systems theory to study the transient behaviour of complex Systems of Congestion. (vi) The creation of Chaos Theory in recent decades suggests that it may be employed as a useful tool in analysing Systems of Congestion. Iterative Chaos Theory methods of orbit generation for complete Systems of Congestion are therefore examined. The use of such orbit generation methods is found to be satisfactory for simple Systems of Congestion. More than a perfunctory knowledge of chaos mapping is however required. The simplicity of modelling is emphasized. (vii) Based on the results of benchmarking the creation of dynamic system orbits against an existing simulation method, the research advances to modelling of the transient operation of complex systems. Once again the iterative method of orbit generation displays the ease of modelling while simultaneously unfolding system dynamics graphically. (viii) One may hopefully contend that a tool of eminent utility has been developed to aid practitioners in studying and optimizing Systems of Congestion. / Thesis (PhD (Industrial Engineering))--University of Pretoria, 2006. / Industrial and Systems Engineering / Unrestricted

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The objective of this master thesis is to optimize a number of service desk operators in Atos IT Solutions and Services s.r.o. The thesis introduces a general and ITIL methodology definition of the service desk. The practical analysis section covers data mining in order to carry out an analysis and propose measures leading to optimal utilization of service desk employees. The method applied in the thesis allows a creation of service desk services demand predictions for any given period of time.

La génération aléatoire d'objets combinatoires est un problème qui se pose dans de nombreux domaines de recherche (réseaux de communications, physique statistique, informatique théorique, combinatoire, etc.). Couramment, la distribution des échantillons est définie comme la distribution stationnaire d'une chaîne de Markov ergodique. En 1996, Propp et Wilson ont proposé un algorithme permettant l'échantillonnage sans biais de la distribution stationnaire. Ce dernier appelé aussi algorithme de simulation parfaite, requiert la simulation en parallèle de tous les états possibles de la chaîne. Plusieurs stratégies ont été mises en œuvre afin de ne pas avoir à simuler toutes les trajectoires. Elles sont intrinsèquement liées à la structure de la chaîne considérée et reposent essentiellement sur la propriété de monotonie, la construction de processus bornants qui exploitent la structure de treillis de l'espace d'états ou le caractère local des transitions. Dans le domaine des réseaux de communications, on s'intéresse aux performances des réseaux de files d'attente. Ces derniers se distinguent en deux groupes : ceux dont la distribution stationnaire possède une forme produit qui est facile à évaluer par le calcul et les autres. Pour ce dernier groupe, on utilise la génération aléatoire pour l'évaluation de performances. De par la structure des chaînes qui leurs sont associées, les réseaux ouverts de files d'attente se prêtent bien à la simulation via l'algorithme de simulation parfaite mais pas les réseaux fermés. La difficulté réside dans la taille de l'espace des états qui est exponentielle en le nombre de files à laquelle s'ajoute une contrainte globale à savoir le nombre constant de clients. La contribution principale de cette thèse est une nouvelle structure de données appelée diagramme. Cette structure est inspirée de la programmation dynamique et introduit une nouvelle technique de construction de processus bornant. La première partie du manuscrit est consacrée à la mise en œuvre de l'algorithme de Propp et Wilson pour des réseaux fermés n'étant pas nécessairement à forme produit. La représentation des états par un diagramme et l'opération de transition pour le processus bornant a dès lors une complexité polynomiale en le nombre de files et de clients. Cette technique est ensuite étendue aux réseaux fermés multiclasses ainsi qu'aux réseaux possédant des synchronisations. Une spécification des ensembles d'objets pouvant être représentés par un diagramme ainsi que des algorithmes agissant sur cette structure de données sont également proposés dans cette thèse. La méthode de Botzmann est une autre technique de simulation sans biais. Basée sur la combinatoire analytique, elle permet l'échantillonnage uniforme d'objets appartenant à une même classe combinatoire. Elle est employée dans la seconde partie de cette thèse afin d'échantillonner la distribution stationnaire de réseaux fermés à forme produit et pour la génération des multi-ensembles de taille fixe. Dans ce cadre, les diagrammes sont une nouvelle fois mis à profit. Enfin, la troisième partie présente les logiciels découlant des travaux présentés tout au long de ce travail, et qui implémentent les diagrammes et mettent en œuvre la simulation parfaite de réseaux fermés de files d'attente. / Random generation of combinatorial objects is an important problem in many fields of research (communications networks, theoretical computing, combinatorics, statistical physics, ...). This often requires sampling the stationary distribution of an ergodic Markov chain. In 1996, Propp and Wilson introduced an algorithm to produce unbiased samples of the stationary distribution, also called a perfect sampling algorithm. It requires parallel simulation of all possible states of the chain. To avoid simulating all the trajectories, several strategies have been implemented. But they are related to the structure of the chain and require a monotonicity property, or a construction of a bounding chain that exploits the lattice structure of the state space or the local character of the transitions.In the field of communications networks, attention is paid to the performance of queueing networks, that can be distinguished into two groups: the networks that have a product form stationary distribution which is easy to compute. Random generation can be used for the others. Perfect sampling algorithms can be used for open queueing networks, thanks to the lattice structure of their state space. Unfortunately, that is not the case for closed queueing networks, due to the size of the state space which is exponential in the number of queues and a global constraint (a constant number of customers). The main contribution of this thesis is a new data structure called a diagram. It is inspired by dynamic programming and allows a new technique of construction of bounding processes. The first part of the manuscript is devoted to the implementation of the Propp and Wilson algorithm for closed queueing networks. The representation of a set of states by a diagram and the transition operation for the bounding process has a polynomial complexity in the number of queues and customers. This technique is extended to closed multi-class networks and to networks with synchronizations. Specification of sets of objects that can be represented by a diagram and generic algorithms that use this data structure are proposed in this manuscript. The Boltzmann method is another unbiased sampling technique. It is based on analytical combinatorics and produces uniform samples from objects that belong to the same combinatorial class. It is used in the second part of this thesis in order to sample the stationary distribution of closed networks with product form and for the generation of multisets of fixed cardinality. Diagrams are used again in this context. Finally, the third part presents the software produced during this thesis, implementing diagrams and perfect simulation of closed queueing networks.

abstract: Modern manufacturing systems are part of a complex supply chain where customer preferences are constantly evolving. The rapidly evolving market demands manufacturing organizations to be increasingly agile and flexible. Medium term capacity planning for manufacturing systems employ queueing network models based on stationary demand assumptions. However, these stationary demand assumptions are not very practical for rapidly evolving supply chains. Nonstationary demand processes provide a reasonable framework to capture the time-varying nature of modern markets. The analysis of queues and queueing networks with time-varying parameters is mathematically intractable. In this dissertation, heuristics which draw upon existing steady state queueing results are proposed to provide computationally efficient approximations for dynamic multi-product manufacturing systems modeled as time-varying queueing networks with multiple customer classes (product types). This dissertation addresses the problem of performance evaluation of such manufacturing systems. This dissertation considers the two key aspects of dynamic multi-product manufacturing systems - namely, performance evaluation and optimal server resource allocation. First, the performance evaluation of systems with infinite queueing room and a first-come first-serve service paradigm is considered. Second, systems with finite queueing room and priorities between product types are considered. Finally, the optimal server allocation problem is addressed in the context of dynamic multi-product manufacturing systems. The performance estimates developed in the earlier part of the dissertation are leveraged in a simulated annealing algorithm framework to obtain server resource allocations. / Dissertation/Thesis / Doctoral Dissertation Industrial Engineering 2020

The master’s thesis solves models of queueing systems, which use the property of Markov chains. The queueing system is a system, where the objects enter into this system in random moments and require the service. This thesis solves specifically such models of queueing systems, in which the intervals between the objects incomings and service time have exponential distribution. In the theoretical part of the master’s thesis I deal with the topics stochastic process, queueing theory, classification of models and description of the models having Markovian property. In the practical part I describe realization and function of the program, which solves simulation of chosen model M/M/m. At the end I compare results which were calculated in analytic way and by simulation of the model M/M/m.

Hospital systems in the United States are facing a dilemma regarding capacity management in the emergency department (ED) and the inpatient care setting. The average wait time in EDs across the United States exceeds 98 minutes, which is also the point at which patients begin to abandon healthcare treatment. The purpose of this quantitative study was to examine the use of queueing theory in capacity management on length-of-stay (LOS) rates, left-without-being-seen (LWBS) rates, and boarding rates in the ED and inpatient setting. The boarding rates represent the rate in which patients were roomed in the ED but required inpatient care. This study assessed the relationships between capacity management using queueing theory and a reduction in the aforementioned rates compared to traditional processes across systems within the continental United States. A linear regression analysis with a confidence interval 95% paired with an independent sample t test was used to analyze the secondary datasets. A sample size of approximately 33,000 patients was tested in the areas of LOS, LWBS, and boarding. The results of the analysis determined that access was improved in the ED and inpatient setting when queueing theory was deployed within the hospital system compared to traditional processes for managing capacity within the system. Queuing theory used for capacity management resulted in lower LOS, LWBS, and boarding rates. The implications of this study for positive social change include the opportunity to provide greater access to care for the population as a whole, and better health outcomes for the promotion of population health.

<div>My dissertation consists of three chapters in the field of managerial economics and experimental economics. The first chapter studies the ratchet effect and the possible ways to mitigate it. Specifically, I conduct a controlled experiment to test the effectiveness of job rotation in eliminating the ratchet effect. Additionally, I compare effort provision between the situation where agents are rotated exogenously and the situation where the principal rotates agents endogenously. The experiment shows that the ratchet effect is effectively reduced both when workers are informed that they will be rotated in the future and when a principal has a costly option of rotating agents.</div><div> </div><div><br></div><div>The second and third chapter are based on joint work with Prof. Yaroslav Rosokha. In the second chapter, we study a single-queue system in which human servers have discretion over the effort with which to process orders that arrive stochastically. We show theoretically that the efficient outcome in the form of high effort can be sustained in the subgame perfect equilibrium if the interactions are long term (even when each server has a short-term incentive to free ride). In addition, we show that queue visibility plays an important role in the type of strategies that can sustain high-effort equilibrium. In particular, we show that limiting feedback about the current state of the queue is beneficial if servers are patient enough. We conduct a controlled lab experiment to test the theoretical predictions and find that when the queue is visible, human subjects cooperate if the queue is long, but defect if the queue is short. We also find that cooperation is hard to achieve when the queue is not visible. </div><div><br></div><div>In the third chapter, we report another lab experiment to test the theory developed in the second chapter. In the new experiment, we provide a more natural queueing frame for the subjects rather than the neutral language used in the second chapter. We also increase the number of matches in each treatment. We find that effort increases with the expected duration of the interaction. We also find that visibility has a strong impact on the strategies that human subjects use to provide effort. As a result, providing less visibility makes servers more willing to provide high effort if they are patient enough.</div>