The classical n-bugs problem has attracted considerable attention from researchers. This problem stems from the study of movement of a group of animals. In the context of multi- agent systems the problem has been modelled as cyclic pursuit. Under this paradigm, every agent, indexed i, chases its unique leader, agent i + 1 (modulo n), with n being the total number of agents. In the existing literature, cyclic pursuit has been studied for homogeneous agents where each agent’s velocity is proportional to the distance separating it from its leader and is directed along the line joining it to its leader. The constant of proportionality, initially chosen to be the same for all the agents, resulted in consensus in position, without the need for any centralized controller. Later, the constant of proportionality, alternately called the gain, was allowed to be heterogeneous and positional consensus was still achieved. Moreover, it was shown that the point of convergence, where the agents rendezvous, could be chosen at will, except for some diagnostic cases. In this thesis, besides admitting heterogeneous gains, the agents are assumed to pursue their respective leaders with an angle of deviation from the line joining them to their corresponding leaders. This expands the reachability set (set of points where the agents can rendezvous) for the system of agents to include points that were hitherto unreachable. Sufficient conditions for stability of such systems have been derived in this thesis. Detailed analysis of the reachability set has also been carried out. Some researchers have also investigated hierarchical cyclic pursuit, where there are multiple levels of pursuit. For instance, in the two level hierarchical pursuit, the agents are divided into m groups of n agents each, where each agent in a group chases its leader within the group as well as a similarly indexed agent in its leading group. Thus, groups of agents are also in cyclic pursuit. So far, only homogeneous gains were considered under this paradigm. The present thesis admits heterogeneous gains and establishes necessary and sufficient conditions for the stability of heterogeneous hierarchical cyclic pursuit, that generalize existing results. Reachable sets are also derived for this case. It is proved that the existing results can be derived as special cases of the ones considered in this thesis. As an extension to a realistic application, the importance of expansion in reachable set vis-a`-vis capturing a moving target is highlighted in this thesis. It has been shown that if the target’s initial position is reachable, then using a control law proposed in the thesis, the target can be captured. This control law is essentially an augmented cyclic pursuit law with the target’s velocity information fed to each agent in addition to the conventional cyclic pursuit command. Analysis has been carried out for agents with double integrator dynamics as well. A control law in conjunction with an algorithm is proposed that helps ensure global reachability of agents, with double integrator dynamics, in cyclic pursuit. Another application, in which cyclic pursuit and a closely related topology called platooning have been coupled together to track the boundaries of unknown regions and constantly monitor them, is addressed in this thesis. This problem is especially important in monitoring forest fire, marine contamination, volcanic ash eruptions, etc., and can protect human life by cordoning off unsafe regions using multiple autonomous agents. Lastly, discrete time cyclic pursuit laws are analyzed to obtain results similar to the continuous time counterparts that exist in the literature. Moreover, heterogeneous gains and deviations are admitted similar to the continuous time version considered in this thesis. Gershgorin’s theorem is used extensively to arrive at sufficient conditions for the stability of such discrete time deviated cyclic pursuit systems. Reachability sets are also derived. In case of discrete time systems, loss of synchronization due to no common clock for autonomous agents is a very realistic scenario. This thesis obtains some results on the stability of such asynchronous cyclic pursuit systems and indicates that special precautions are needed for dealing with heterogeneous cyclic pursuit systems even when one gain is negative, since the system may not converge, depending on the initial positions of the agents and the sequence of updates.

The analysis of sequential data is important in business, science, and engineering, for tasks such as signal processing, user behavior mining, and commercial transactions analysis. In this dissertation, we build upon the Collective Dynamical Modeling and Clustering (CDMC) framework for discrete time series modeling, by making contributions to clustering initialization, dynamical modeling, and scaling. We first propose a modified Dynamic Time Warping (DTW) approach for clustering initialization within CDMC. The proposed approach provides DTW metrics that penalize deviations of the warping path from the path of constant slope. This reduces over-warping, while retaining the efficiency advantages of global constraint approaches, and without relying on domain dependent constraints. Second, we investigate the use of semi-Markov chains as dynamical models of temporal sequences in which state changes occur infrequently. Semi-Markov chains allow explicitly specifying the distribution of state visit durations. This makes them superior to traditional Markov chains, which implicitly assume an exponential state duration distribution. Third, we consider convergence properties of the CDMC framework. We establish convergence by viewing CDMC from an Expectation Maximization (EM) perspective. We investigate the effect on the time to convergence of our efficient DTW-based initialization technique and selected dynamical models. We also explore the convergence implications of various stopping criteria. Fourth, we consider scaling up CDMC to process big data, using Storm, an open source distributed real-time computation system that supports batch and distributed data processing. We performed experimental evaluation on human sleep data and on user web navigation data. Our results demonstrate the superiority of the strategies introduced in this dissertation over state-of-the-art techniques in terms of modeling quality and efficiency.

Well logs and formation testers are routinely used for detection and quantification of hydrocarbon reserves. Overbalanced drilling causes invasion of mud filtrate into permeable rocks, hence radial displacement of in-situ saturating fluids away from the wellbore. The spatial distribution of fluids in the near-wellbore region remains affected by a multitude of petrophysical and fluid factors originating from the process of mud-filtrate invasion. Consequently, depending on the type of drilling mud (e.g. water- and oil-base muds) and the influence of mud filtrate, well logs and formation-tester measurements are sensitive to a combination of in-situ (original) fluids and mud filtrate in addition to petrophysical properties of the invaded formations. This behavior can often impair the reliable assessment of hydrocarbon saturation and formation storage/mobility. The effect of mud-filtrate invasion on well logs and formation-tester measurements acquired in vertical wells has been extensively documented in the past. Much work is still needed to understand and quantify the influence of mud-filtrate invasion on well logs acquired in horizontal and deviated wells, where the spatial distribution of fluids in the near-wellbore region is not axial-symmetric in general, and can be appreciably affected by gravity segregation, permeability anisotropy, capillary pressure, and flow barriers. This dissertation develops a general algorithm to simulate the process of mud-filtrate invasion in vertical and deviated wells for drilling conditions that involve water- and oil-base mud. The algorithm is formulated in cylindrical coordinates to take advantage of the geometrical embedding imposed by the wellbore in the spatial distribution of fluids within invaded formations. In addition, the algorithm reproduces the formation of mudcake due to invasion in permeable formations and allows the simulation of pressure and fractional flow-rate measurements acquired with dual-packer and point-probe formation testers after the onset of invasion. An equation-of-state (EOS) formulation is invoked to simulate invasion with both water- and oil-base muds into rock formations saturated with water, oil, gas, or stable combinations of the three fluids. The algorithm also allows the simulation of physical dispersion, fluid miscibility, and wettability alteration. Discretized fluid flow equations are solved with an implicit pressure and explicit concentration (IMPEC) scheme. Thermodynamic equilibrium and mass balance, together with volume constraint equations govern the time-space evolution of molar and fluid-phase concentrations. Calculations of pressure-volume-temperature (PVT) properties of the hydrocarbon phase are performed with Peng-Robinson's equation of state. A full-tensor permeability formulation is implemented with mass balance equations to accurately model fluid flow behavior in horizontal and deviated wells. The simulator is rigorously and successfully verified with both analytical solutions and commercial simulators. Numerical simulations performed over a wide range of fluid and petrophysical conditions confirm the strong influence that well deviation angle can have on the spatial distribution of fluid saturation resulting from invasion, especially in the vicinity of flow barriers. Analysis on the effect of physical dispersion on the radial distribution of salt concentration shows that electrical resistivity logs could be greatly affected by salt dispersivity when the invading fluid has lower salinity than in-situ water. The effect of emulsifiers and oil-wetting agents present in oil-base mud was studied to quantify wettability alteration and changes in residual water saturation. It was found that wettability alteration releases a fraction of otherwise irreducible water during invasion and this causes electrical resistivity logs to exhibit an abnormal trend from shallow- to deep-sensing apparent resistivity. Simulation of formation-tester measurements acquired in deviated wells indicates that (i) invasion increases the pressure drop during both drawdown and buildup regimes, (ii) bed-boundary effects increase as the wellbore deviation angle increases, and (iii) a probe facing upward around the perimeter of the wellbore achieves the fastest fluid clean-up when the density of invading fluid is larger than that of in-situ fluid. / text

Le proverbe est un matériau linguistique fréquemment employé mais qui, aujourd’hui encore, soulève de vifs débats. Notre thèse a donc pour vocation d’étudier les caractères principaux de ce type de phrase pour en dégager les caractéristiques essentielles. Ainsi, nous analyserons des éléments d’ordre purement formel mais aussi des éléments liés à la nature de ce matériau. De plus, certaines questions fondamentales sont soulevées par l’existence de formes dérivées de proverbes, à savoir les variantes et les proverbes détournés. Que dire de ces phrases ? Remettent-elles en question le caractère figé du proverbe ? Enfin, nous analyserons le sens du proverbe. En effet, il est parfois malaisé de comprendre le lien entre ce que déclare explicitement le proverbe et le sens qui lui est attaché. Nos réflexions poseront donc une définition argumentée du proverbe qui servira de base à l’élaboration d’un dictionnaire thématique bilingue espagnol-français sur le thème de l’argent. / Proverb is frequently used as a linguistically material that, still nowadays, raises lively discussions. Therefore, our thesis has for goal to study main characteristics of this kind of sentence in order to extract fundamental particularities. Thus, we are going to analyse purely formal elements as well as linked elements to it’s nature. In addition to this, some fundamental questions arise due to revised proverbs existence like “variants” and “deviated proverbs”. What can we say about these sentences? Do they modify proverbs’ formal structure? At last, we shall analyse proverb’s meaning because sometimes it is not obvious to understand the link between it’s literal sense and it’s meaning. Our reflections have to argue proverb’s meaning through a definition we will use in order to elaborate a bilingual French-Spanish dictionary whose theme will be money.

Made available in DSpace on 2017-07-21T20:32:01Z (GMT). No. of bitstreams: 1 Rosemeri Hoffmann.pdf: 512979 bytes, checksum: 6c456bc7dee5969a77390a9302ec13d4 (MD5) Previous issue date: 2006-03-30 / This research aims to evidence the importance of the language conceptions to be taken as the beginning in the definition of teaching/learning methodologies of the Portuguese language and to have the teacher to be aware that his pedagogic practice in the Portuguese teaching has direct relation with his language conception. This research aimed to investigate which language teaching conception that is according to the pedagogic practice of the deviated student and the Portuguese language teacher former of the language course of the State University of Ponta Grossa. Through this research, it was checked how the deviated students evaluate the language course and the questions releated to the theories and practices that give support to the initial formation of the teacher. The research is devided into five chapters structured this way: the first one regards the theories related to Bakhthin, Geraldi, Suassuna and Travaglia, among others; the second reagards a brief historical of the language course; the third covers the conceptions of the former teachers; the fourth treats the methodological matters; the fifth, the teaching conceptions of the deviated students, the, and the last one focuses the final considerations. This work developed from the methodological paths described by Triviños, that align the procedures with qualitative and quantitative focus, even though, the major enfasis is in the qualitative research, considering that one assists better proposed objectives. This research was classified how the case study, it was used as data gathering a half-structed interwiew with deviated students from the language course with were graduated by the State University of Ponta Grossa in the period of 1993 to 2003 and with teachers from the methodoly and teaching practice subject. The data gathering was performed in 2004 which lasted a year. / Esta pesquisa visa a ressaltar a importância de as concepções de linguagem serem tomadas como ponto de partida na definição de metodologias de ensino/aprendizagem de Língua Portuguesa e de conscientizar o professor de que a sua prática pedagógica no ensino do Português tem relação direta com a sua concepção de linguagem.Objetivou-se nesta pesquisa investigar qual a concepção de ensino de linguagem que subjaz a prática pedagógica do aluno egresso e do professor-formador de Língua Portuguesa do Curso de Letras da Universidade Estadual de Ponta Grossa.Por meio desta pesquisa, verificou-se como os egressos avaliam o Curso de Letras e as questões relacionadas às teorias e práticas que dão suporte à formação inicial do professor.A pesquisa está dividida em cinco capítulos assim estruturados: o primeiro capítulo contempla os referenciais teóricos que privilegiaram as obras de Bakthin, Geraldi, Suassuna e Travaglia entre outros; o segundo, trata de um breve histórico do Curso de Letras; o terceiro aborda as concepções dos professores formadores; o quarto trata das questões metodológicas; o quinto, as concepções de ensino dos alunos egressos e por último, as considerações finais. Este trabalho desenvolveu-se a partir dos caminhos metodológicos descrito por Triviños, delineamento esse que mescla os procedimentos com caráter qualitativo e quantitativo, mesmo assim a ênfase maior se dá aos pressupostos da pesquisa qualitativa, considerando que esta atenderia melhor aos objetivos propostos. Classificou-se esta pesquisa como um Estudo de Caso, foi utilizado como instrumento de coleta de dados a entrevista semi-estruturada com alunos egressos do Curso de Letras (Licenciatura em Língua Portuguesa) que se formaram pela Universidade Estadual de Ponta Grossa no período de 1993 a 2003 e com os professoresformadores da Disciplina de Metodologia e Prática de Ensino dessa Instituição. A coleta de dados foi realizada no ano de 2004, com a duração de um ano.

This study aims to investigate hydraulics and the flow characteristics of drilling fluids inside annulus and to understand the mechanism of cuttings transport in horizontal and deviated wellbores. For this purpose, initially, extensive experimental studies have been conducted at Middle East Technical University, Petroleum &amp / Natural Gas Engineering Flow Loop using water and numerous drilling fluids for hole inclinations from horizontal to 60 degrees, flow velocities from 0.64 m/s to 3.05 m/s, rate of penetrations from 0.00127 to 0.0038 m/s, and pipe rotations from 0 to 120 rpm. Pressure loss within the test section and stationary and/or moving bed thickness are recorded. New friction factor charts and correlations as a function of Reynolds number and cuttings bed thickness with the presence of pipe rotation for water and drilling fluids in horizontal and deviated wellbores are developed by using experimental data. Meanwhile empirical correlations that can be used easily at the field are proposed for predicting stationary bed thickness and frictional pressure loss using dimensional analysis and the effect of the drilling parameters on hole cleaning is discussed. It has been observed that, the major variable influencing cuttings transport is fluid velocity. Moreover, pipe rotation drastically decreases the critical fluid velocity that is required to prevent the stationary cuttings bed development, especially if the pipe is making an orbital motion. A decrease in the pressure loss is observed due to the bed erosion while rotating the pipe. Cuttings transport in horizontal annulus is modeled using a CFD software for different fluid velocities, pipe rotation speeds and rate of penetrations. The CFD model is verified by using cuttings transport experiments. A mathematical model is also proposed to predict the flow characteristics of Newtonian fluids in concentric horizontal annulus with drillpipe rotation. The Navier-Stokes equations of turbulent flow are numerically solved using finite differences technique. A computer code is developed in Matlab 2007b for the proposed model. The performance of the proposed model is compared with the experimental data which were available in the literature and gathered at METU-PETE Flow Loop as well as Computational Fluids Dynamics (CFD) software. The results showed that the mechanistic model accurately predicts the frictional pressure loss and the velocity profile inside the annuli. The model&rsquo / s frictional pressure loss estimations are within an error range of &plusmn / 10%.

Electrical Submersible Pumping (ESP) is a well known artificial lift technique in reservoirs having high-water cut and low gas-oil ratio. It is known as an effective and economical method of producing large volumes of fluid under different well conditions. ESP equipments are capable of producing in a range of 200 b/d to 60.000 b/d. A case study was done, by designing 10 deviated or horizontal wells selected from the Y-oilfield in Western Siberia. SubPUMP software developed by IHS Energy is used for designing the ESP systems of these wells. These 10 wells will be working with variable speed drives. After selecting the available equipment from the inventory, the best running frequencies are selected for these wells. Evaluations of the designs are made from the pump performance graphs of each well. The pumps should work within their optimum efficiency ranges. These ranges can be seen from the pump performance curves. If the designs made are not within these efficiency ranges, designs should be evaluated and selecting new equipment should be should be an option. Because working outside the optimum efficiency ranges will decrease the production, shorten the runlifes of the pumps and the production will not be stable.

[pt] A ocorrência de eventos de perfuração em poços de óleo e gás é frequente, porém indesejada, uma vez que acarreta aumento no tempo e custo das operações. Sua ocorrência pode levar à perda de circulação do fluido, desmoronamento da parede do poço, restrição da sua funcionalidade, danos à plataforma, problemas ambientais e mesmo a perda de vidas humanas. Desta forma, o conhecimento das tensões é essencial para a estimativa da estabilidade do poço e aumento da segurança da perfuração. Existem diversos métodos para prever a tensão horizontal mínima, entretanto, para a máxima, ainda há dificuldades na sua determinação. No caso de poços inclinados, este cálculo se torna ainda mais complexo, uma vez que as tensões regionais não são alinhadas com o eixo do poço. Identificada essa necessidade, e partindo do princípio de que ao menos um poço já tenha sido perfurado em um campo e que este apresentou instabilidades do tipo colapso ou fraturamento induzido, esta dissertação trabalha na implementação de um algoritmo capaz de obter a magnitude da tensão horizontal máxima que levou ao surgimento dos mesmos. As fraturas Induzidas são falhas de tração, enquanto os Breakouts são gerados pelo colapso da parede do poço por falhas de compressão. Ambos devem ser devidamente identificados a partir de perfis de imagem. Os algoritmos implementados envolvem solução analítica, calculada através de métodos implícito e explícito. O procedimento para a rotação das tensões para poços inclinados é baseado em formulação presente na literatura, e os cálculos das tensões ao redor da parede do poço, nas equações de Kirsch. O fraturamento do material é avaliado de acordo com a tensão de cut-off, e o de ruptura, a partir do critério de Mohr-Coulomb ou Lade-Ewy. Os métodos desenvolvidos são comparados entre si, relatando suas vantagens e desvantagens. Aplicando uma vasta variação de inclinação e azimute do poço, os resultados alcançados apresentam uma diferença pequena com relação aos obtidos por meio de pacotes comerciais, sendo considerados satisfatórios. / [en] The occurrence of oil and gas well drilling events is common, but undesirable, once it increases time and cost of operations. Its occurence can lead to loss of fluid circulation, wellbore wall collapse, restriction of its functionality, platform damage, environmental issues and even the lost of human lives. stresses knowledge is essential to wellbore stability estimation and to the improvement of drilling safety. In fact, there are some methods and tests to compute the minimum horizontal stress, but there still exist difficulties on maximum horizontal stress determination. In the case of deviated wells, the calculations are even more complexes due to the lack of alignment between the regional stresses and well axis. Identified that problem, and considering that at least one wellbore has been drilled in a field and presented compressive or tensile instabilities, this dissertation works on the implementation of algorithms capable of obtaining the maximum horizontal stress magnitude that lead the appearance of breakout or induced fracture. The instability problems are identified and previously interpreted through image logs. The implemented algorithms involve an analytical solution, which is calculated by an explicit method and an implicit one, to the stated problem. The procedure to the stresses rotation on deviated wells used at this work is based on the formulation presented on technical literature, and the calculation of the stresses around the wellbore wall, on Kirsch s equation. The failure of the material is evaluated using a tensile cutoff for induced fractures and Mohr-Coulomb or Lade-Ewy criteria for breakouts. The developed methods are compared between each other, presenting the advantages and disadvantages of then. The results, applying a large variation on the wellbore inclination and azimuth, show that the values accomplished a low difference in relation to the obtained by using a commercial software, being considered as satisfactory.