Cálculo de integral indefinida por mudança de variável [Audiodescrição]

Versão com menu acessível para leitores de tela e vídeo com audiodescrição.

Cinemática de partículas em fluidos de viscosidade variável com o tempo e sua aplicação na construção de poços de petróleo: avaliação durante paradas operacionais

The new oil reservoirs discoveries in onshore and ultra deep water offshore fields and complex trajectories require the optimization of procedures to reduce the stops operation during the well drilling, especially because the platforms and equipment high cost, and risks which are inherent to the operation. Among the most important aspects stands out the drilling fluids project and their behavior against different situations that may occur during the process. By means of sedimentation experiments, a correlation has been validated to determe the sedimentation particles velocity in variable viscosity fluids over time, applying the correction due to effective viscosity that is a shear rate and time function. The viscosity evolution over time was obtained by carrying out rheologic tests using a fixed shear rate, small enough to not interfere in the fluid gelling process. With the sedimentation particles velocity and the fluid viscosity over time equations an iterative procedure was proposed to determine the particles displacement over time. These equations were implemented in a case study to simulate the cuttings sedimentation generated in the oil well drilling during stops operation, especially in the connections and tripping, allowing the drilling fluid project in order to maintain the cuttings in suspension, avoiding risks, such as stuck pipe and in more drastic conditions, the loss of the well

Metodologia para avaliação de cinemática de partículas gasosas em fluidos de viscosidade variável com o tempo e sua aplicação na construção de poços de petróleo

Many challenges have been presented in petroleum industry. One of them is the preventing of fluids influx during drilling and cementing. Gas migration can occur as result of pressure imbalance inside the well when well pressure becomes lower than gas zone pressure and in cementing operation this occurs during cement slurry transition period (solid to fluid). In this work it was developed a methodology to evaluate gas migration during drilling and cementing operations. It was considered gel strength concept and through experimental tests determined gas migration initial time. A mechanistic model was developed to obtain equation that evaluates bubble displacement through the fluid while it gels. Being a time-dependant behavior, dynamic rheological measurements were made to evaluate viscosity along the time. For drilling fluids analyzed it was verified that it is desirable fast and non-progressive gelation in order to reduce gas migration without affect operational window (difference between pore and fracture pressure). For cement slurries analyzed, the most appropriate is that remains fluid for more time below critical gel strength, maintaining hydrostatic pressure above gas zone pressure, and after that gels quickly, reducing gas migration. The model developed simulates previously operational conditions and allow changes in operational and fluids design to obtain a safer condition for well construction

Variabilidade espacial de atributos químicos de um argissolo para aplicação de insumos à taxa variável em diferentes formas de relevo

A agricultura de precisão implica análise da variabilidade espacial de fatores de produção e a aplicação de insumos de forma localizada. Várias são as causas que condicionam a variabilidade espacial dos solos, sendo o relevo um dos fatores mais importantes. O presente estudo teve por objetivo analisar a variabilidade espacial dos atributos químicos do solo e a elaboração de mapas de necessidade de aplicação de insumos de forma localizada, em áreas com diferentes formas de relevo. Duas parcelas de 1 ha cada foram delimitadas em áreas com topografia côncava e convexa. Foram retiradas, em cada área, 242 amostras de solos em 121 pontos, nas profundidades de solo de 0,00-0,20 m e 0,20-0,40 m. Os resultados de análise química foram submetidos às análises da estatística descritiva, geoestatística e interpolação por krigagem. A área convexa apresentou maior variabilidade espacial do solo em relação a área côncava. A adoção da agricultura de precisão possibilitou economia de aproximadamente 25 kg ha-1 de P2O5 na área côncava.

O Fundef e o Fundeb como política de financiamento para a valorização do magistério: efeitos na carreira e na remuneração dos professores da rede pública estadual de ensino do RN

Le présent étude analyse les effets de la politique de financement de l éducation de base, par les Fonds contables, Fundef et Fundeb, et sa proposition de valorisation de l enseignement, en considerant les dimensions de la carrière et de la rémunération des professeurs de l éducation publique de l état du Rio Grande do Norte, entre les années de 1996 et 2000. Pour comprendre les contraintes de l évaluation des politiques publiques, en cherchant aussi les contribution en Marx (1996) selon qui « le concret est concret » et que la dialétique du concret peut appuyer pour la tentative de capter le fenomène étudié. On a utilisé encore le référentiel bibliographique relatif au financement de l éducation et la valorisation de l enseignement à partir de la littérature reférente aux dimensions de l objet (Fundef et Fundeb) et (carrière et rémuneration). Dans la recherche documental, au-delà des législations, directrices nationales et locales pertinentes, se sont utilisés des donnés référents aux ressources, disponibles à la Finbra, Trésor National, SIOPE/RN, INEP/MEC, des informations du résumé de la feuille et feuille de payement du Secrétariat d État, de l Éducation et de la Culture (SEEC) et 289 bulletins de salaire de 21 professeurs. On a réalisé interview semi structurée avec une quantité de 9 professeurs, reférent à la carrière, et un questionaire appliqué à 12 professeurs relatif à la remuneration. On considère que sur les résultats reférents aux indicateurs éducationnel, dans la période Fundef il y a eu une réduction des inscriptions aux écoles de l état comme aussi aux fonctions des professeurs de l Enseignement Fondamental, et cela correspond à 37%. À partir de la vigence du Fondebe (2007 - 2010) ces indicateurs ont équalisé. Pendant toute la période, 1996 et 2010 il y a eu une augmentation des inscriptions de 119,03%, et aussi aux fonctions des professeurs de 77,44%. Par rapport aux informations de financement, on a constaté que, du minimum exigé (60%) sur l aplication des fonds à la rémuneration de l enseignant, on applique pour la période des deux fonds, plus que le minimum exigé, c est-à-dire de 83,29% à 98,89% des fonds. Les effets des fonds sur la carrière des 9 professeurs n ont pas été satisfactoires, si l on considère la promotion et la progression. Au cas de la promotion des 9 de ces professeurs, un seul a évolué son niveau (les titres) mais a, au même temps, rétroagit dans sa progression. Pour la progression des 9 professeurs, 8 d entre eux ont sa progression retardée, ce qui correspond à entre 2 et 5 classes, et ce qui provoque un préjudice qui varie entre 10% à 45% sur sa remunération. La différence d une classe à l autre correspond à 5% de son salaire. On évalue que les avantages financières contribuent pour la remunération avec un pourcentage plus élevé que son salaire, ce qui diminuent pendant lo Fundeb. Par rapport à la remunération un professeur de 24 ans de service avec formation, n arrive même pas à gagner 2 salaires minimums. Le professeur de 30 ans de service, maître, reçoit un salaire, en 2010, qui correspond a moins de 3 salaires minimums, c est-à-dire, une proportion de 2,82 et une remuneration qui correspond à un peu plus que 3 salaires minimums, c est-à-dire, une proportion de 3,66. L enseignement n est pas très favorisé si on le met face à d autres profession qui ont aussi l exigence de formation supérieure, ce qui provoque un effet négatif pour voir l enseignement comme profession. À propos des effets sur la rémuneration, on conclue qu il y a eu une amélioration mais encore insufisante, surtout si l on compare au Salaire Minimum annuel. On évalue que les fonds Fundef et Fundeb n ont pas été capables de promouvoir la valorisation de l enseignement dans le contexte de carrière et rémuneration. On observe quelques résultats négatif dans la politique de fonds, une fois qu il y aurait en avoir avec l incapacité de tel politique en promouvoir la dite valorisation de l enseignement, ce qui est une des causes, le financement avec des restriction budgétaire

Fundef (1996-2006): a remuneração dos professores do ensino fundamental da rede pública municipal de Natal/RN

This work discusses about the teacher salary in the primary school after the creation of the Fundo de Manutenção e Desenvolvimento do Ensino Fundamental e Valorização do Magistério (Fundef), in the public schools in Natal/RN, from 1996 to 2006. The salary is considered one of the politic dimensions of the valorization of teaching. We aim to analyze the implication of this fund to the teacher remuneration, with different levels of training, in the early career, comparing it to the annual minimum salary, during the same period. This study has a historic-critic approach, establishing the relationship between the elements into a particular context (valorization of teaching/ teacher salary) and the elements from general contexts (financing/ Fundef). Analyzing data of the teacher remuneration from municipal payroll and comparing them to the annual national minimum salary gave us the result that the teachers, in their early career, do not have remuneration with a satisfactory evolution. Teachers that finished high school received until three minimum salaries before the creation of Fundef (1996-1997), after that (in 1998) they received under two minimum salary. In addition to this, independently of the level of the teacher training, their remuneration is under three minimum salaries. Hence, we can infer that the politic of funds is distant from the ideal to valorize the professional of the municipal teaching

Fatores de satisfação de empregados: um estudo com docentes de instituição de educação tecnológica

This Master of Science Thesis deals with investigating the factors affecting employees satisfaction studying the case of teachers on a technological education institution. It is surveyed teachers in a sample of size 42 out of 316. It is used a form that deploys a model of satisfaction antecedents factors comprised of work system, professional development, teaching activity, physical environment, pay, and problems management. The sample was found representative (χ2 test) based on genre, tenure, degrees, and age. The model for satisfaction with the institution presented a adjusted r2 > 0,80 and the main factors affecting it was found to be work system, professional development, and teaching activity. For the satisfaction with the career, the model results with a r2 > 0,70 and as main factors professional development, teaching activitiy and pay. The variables contribuition for the students education and use of suggestions were ones of the main variables appearing in the models. The results suggest an improvement in the model regarding the previous models used by Silva (2003) and Cruz Filho (2007) regarding model explicability of teacher satisfaction

Estabilidade e robustez de um controlador adaptativo indireto por um modelo de referência e estrutura variável

In this thesis, it is developed the robustness and stability analysis of a variable structure model reference adaptive controller considering the presence of disturbances and unmodeled dynamics. The controller is applied to uncertain, monovariable, linear time-invariant plants with relative degree one, and its development is based on the indirect adaptive control. In the direct approach, well known in the literature, the switching laws are designed for the controller parameters. In the indirect one, they are designed for the plant parameters and, thus, the selection of the relays upper bounds becomes more intuitive, whereas they are related to physical parameters, which present uncertainties that can be known easier, such as resistances, capacitances, inertia moments and friction coefficients. Two versions for the controller algorithm with the stability analysis are presented. The global asymptotic stability with respect to a compact set is guaranteed for both cases. Simulation results under adverse operation conditions in order to verify the theoretical results and to show the performance and robustness of the proposed controller are showed. Moreover, for practical purposes, some simplifications on the original algorithm are developed

Avaliação de robustez, desempenho e aplicação do controlador adaptativo por posicionamento de pólos e estrutura variável

In this work, the variable structure adaptive pole placement controller (VS-APPC) robustness and performance are evaluated and this algorithm is applied in a motor control system. The controller robustness evaluation will be done through simulations, where will be introduced in the system the following adversities: time delay, actuator response boundeds, disturbances, parametric variation and unmodeled dynamics. The VS-APPC will be compared with PI control, pole placement control (PPC) and adaptive pole placement controller (APPC). The VS-APPC will be simulated to track a step and a sine reference. It will be applied in a three-phase induction motor control system to track a sine signal in the stator reference frame. Simulation and experimental results will prove the efficiency and robustness of this control strategy

Correspondência estéreo usando imagens em multiresolução com profundidade variável

We propose a multi-resolution, coarse-to-fine approach for stereo matching, where the first matching happens at a different depth for each pixel. The proposed technique has the potential of attenuating several problems faced by the constant depth algorithm, making it possible to reduce the number of errors or the number of comparations needed to get equivalent results. Several experiments were performed to demonstrate the method efficiency, including comparison with the traditional plain correlation technique, where the multi-resolution matching with variable depth, proposed here, generated better results with a smaller processing time

Uma proposta de um controlador adaptativo por posicionamento de pólos e estrutura variável

There are two main approaches for using in adaptive controllers. One is the so-called model reference adaptive control (MRAC), and the other is the so-called adaptive pole placement control (APPC). In MRAC, a reference model is chosen to generate the desired trajectory that the plant output has to follow, and it can require cancellation of the plant zeros. Due to its flexibility in choosing the controller design methodology (state feedback, compensator design, linear quadratic, etc.) and the adaptive law (least squares, gradient, etc.), the APPC is the most general type of adaptive control. Traditionally, it has been developed in an indirect approach and, as an advantage, it may be applied to non-minimum phase plants, because do not involve plant zero-pole cancellations. The integration to variable structure systems allows to aggregate fast transient and robustness to parametric uncertainties and disturbances, as well. In this work, a variable structure adaptive pole placement control (VS-APPC) is proposed. Therefore, new switching laws are proposed, instead of using the traditional integral adaptive laws. Additionally, simulation results for an unstable first order system and simulation and practical results for a three-phase induction motor are shown

Controlador adaptativo por posicionamento de pólos e estrutura variável aplicado ao controle de geradores eólicos baseados em máquina de indução duplamente alimentada

In the last decade, the renewable energy sources have present a major propulsion in the world due to several factors: political, environmental, financial and others. Within this context, we have in particular the energy obtained through wind, wind energy - that has highlighted with rapid growth in recent years, including in Brazil, mostly in the Northeast, due to it s benefit-cost between the clean energies. In this context, we propose to compare the variable structure adaptive pole placement control (VS-APPC) with a traditional control technique proportional integral controller (PI), applied to set the control of machine side in a conversion system using a wind generator based on Double-Fed Induction Generator (DFIG). Robustness and performance tests were carried out to the uncertainties of the internal parameters of the machine and variations of speed reference.

Importância do fluxo de massa e difusão no suprimento de potássio ao algodoeiro como variável de água e potássio no solo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Um estudo na teoria do movimento brownianno com viscosidade variável

In this work we investigate the stochastic behavior of a large class of systems with variable damping which are described by a time-dependent Lagrangian. Our stochastic approach is based on the Langevin treatment describing the motion of a classical Brownian particle of mass m. Two situations of physical interest are considered. In the first one, we discuss in detail an application of the standard Langevin treatment (white noise) for the variable damping system. In the second one, a more general viewpoint is adopted by assuming a given expression to the so-called collored noise. For both cases, the basic diffententiaql equations are analytically solved and al the quantities physically relevant are explicitly determined. The results depend on an arbitrary q parameter measuring how the behavior of the system departs from the standard brownian particle with constant viscosity. Several types of sthocastic behavior (superdiffusive and subdiffusive) are obteinded when the free pamameter varies continuosly. However, all the results of the conventional Langevin approach with constant damping are recovered in the limit q = 1

Criação da matéria em cosmologias com velocidade da luz variável e eletrônico não-linear

In this work we obtain the cosmological solutions and investigate the thermodynamics of matter creation in two diferent contexts. In the first we propose a cosmological model with a time varying speed of light c. We consider two diferent time dependence of c for a at Friedmann-Robertson- Walker (FRW) universe. We write the energy conservation law arising from Einstein equations and study how particles are created as c decreases with cosmic epoch. The variation of c is coupled to a cosmological Λ term and both singular and non-singular solutions are possible. We calculate the "adiabatic" particle creation rate and the total number of particles as a function of time and find the constrains imposed by the second law of thermodynamics upon the models. In the second scenario, we study the nonlinearity of the electrodynamics as a source of matter creation in the cosmological models with at FRW geometry. We write the energy conservation law arising from Einstein field equations with cosmological term Λ, solve the field equations and study how particles are created as the magnetic field B changes with cosmic epoch. We obtain solutions for the adiabatic particle creation rate, the total number of particles and the scale factor as a function of time in three cases: Λ = 0, Λ = constant and Λ α H2 (cosmological term proportional to the Hubble parameter). In all cases, the second law of thermodynamics demands that the universe is not contracting (H ≥ 0). The first two solutions are non-singular and exhibit in ationary periods. The third case studied allows an always in ationary universe for a suficiently large cosmological term