64 resultados para incertezas


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Este trabajo tiene como objetivo comprender los sentidos dados a la relación entre el planeamiento y el proceso de formación continuada por profesores de una escuela pública municipal de la ciudad de Natal (RN). La conjetura guía es la percepción de que los profesores parecen no concebir el planeamiento escolar como espacio de formación colectiva y continuada. Así, esta conjetura es motivo de reflexión a medida que el planeamiento puede ser visto como un proceso cargado por tensiones y conflictos estructurales reprimidos en la escuela. Nuestro principio teórico metodológico es una interpretación de múltiples referencias que parte de conceptos en diferentes modelos de análisis en la comprensión de una realidad en que diferenciadas dimensiones están entremezcladas. Adoptamos como metodología de investigación la Entrevista Comprensiva, en que el objeto de la investigación se construye por medio de la elaboración teórica de las hipótesis surgidas en el campo de la investigación. El investigador busca dominar y personaliza los instrumentos y teoría a un proyecto concreto de investigación, cuya imagen más cercana es lo que se denomina de artesanía intelectual . En el proceso de construcción comprendemos la necesidad de entender el registro de un saber social incorporado por los individuos a su historicidad, a sus orientaciones y definiciones de su acción en relación al conjunto de la sociedad. En este sentido, los profesores entrevistados comentan su entendimiento revelando sentidos sobre cómo hacer efectivo un planeamiento que atienda las realidades del cotidiano de los alumnos. Observamos en nuestros análisis que parte del grupo de profesores tiene consciencia de hacer del planeamiento como base del trabajo docente no apenas dirigido al aspecto práctico elaboración y ejecución -, sino relacionado a un proceso de otros aspectos simultáneos como la reflexión acción-reflexión sobre la acción. De este modo, existe la posibilidad de mejorar el planeamiento transformándolo en más dinámico y participativo a través de los proyectos de trabajo como alternativa de enseñanza y de acercar la práctica pedagógica a la realidad de los alumnos, por ese motivo el planeamiento diario es de fundamental relevancia, ya que el espacio escolar es complejo y dinámico. Sin embargo, percibimos que existe incomprensión del planeamiento como espacio de formación continuada en la escuela en consecuencia de prácticas sin reflexión, y por eso, el proceso de planeamiento tiende a ser visto apenas como técnico y no un proceso político que apunta hacia la acción reflexiva. Por estas razones surgen tensiones externas e internas, unidas a las incertidumbres del trabajo docente en el cotidiano escolar, asociada a los sentimientos antagónicos que pueden ser elementos que dificultan y limitan el trabajo profesional de los docentes, llevándolos a la improvisación. Los profesores sugieren la construcción de la propuesta pedagógica dirigida a la formación continuada, coligada a la introducción de una práctica reflexiva que considere a la colectividad, siendo incluidas la autonomía, la flexibilidad y la abertura del planeamiento, y resaltan la actuación mediadora del coordinador pedagógico como de fundamental importancia para fortalecer el trabajo colectivo en la escuela y de enfatizar practicas reflexivas

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This research, which appears in the form of a dissertation, entitled: Integrative Therapy Community: construction of a listening space to health care workers in primary care, addresses the Integrative Community Therapy (ICT) as a tool to create meeting spaces between health professionals where they can be receptive among one another. With the completion of this study aimed to analyze the ICT as a therapeutic approach and space of listening and speaking for health professionals cited here in order to identify their anxieties, doubts, worries and uncertainties arising from the context of labor relations and the impact of therapeutic experiences under the view of the participants. It was developed as an action-science research, involving several steps. The field of research was the ICT meetings of workers from the units under the Family Health Strategy of Northern Health Districts I and II of the city of Natal, using a qualitative approach. The interpretation of data collected was based on content analysis proposed by Bardin. Finally, this study showed the ICT as a space for dialogue and sharing, with repercussions on labor relations and expansions beyond the ICT meetings, reaching out to family and social relationships, contributing to creating bonds and solidarity networks. Under the view of the participants it was recognized as an experience that optimized the socialization, promoting the alleviation of suffering and increasing the well-being. Based on the study findings, it is inferred that ICT can be considered a viable tool for the receptiveness and humanized care of health care workers.

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A experimentação industrial é um método científico de aprendizagem que visa aprimorar conhecimentos sobre o funcionamento de sistemas, almejando redução de variabilidade e incertezas nos processos produtivos. Em inovação, constitui-se como uma oportunidade de teste e pré-implementação, permitindo à empresa aperfeiçoar seus projetos de inovação antes de levá-los ao mercado. Contudo, para que empresas obtenham sucesso em inovar, faz-se necessário um ambiente favorável à inovação, considerando que a cultura organizacional impacta diretamente no potencial inovador. Uma cultura de inovação bem desenvolvida demanda o envolvimento de todos os líderes da empresa atuando como facilitadores do processo. Nesse contexto, esta pesquisa tem como propósito avaliar o perfil da cultura organizacional visando o uso de experimentação no processo de inovação em uma indústria do ramo alimentício no Estado do Rio Grande do Norte. Para tanto, busca-se, por meio de fundamentação teórica, ampliar a compreensão da relação existente entre os temas experimentação, inovação e cultura organizacional, e tem-se como método de pesquisa, uma abordagem quanti-qualitativa em um estudo de caso. Os dados para análise da pesquisa são coletados por meio de entrevistas e aplicação de questionários. Para avaliar a cultura organizacional, utiliza-se como instrumento o questionário baseado no Modelo de Valores Competitivos, desenvolvido por Cameron e Quinn (2006), aplicado com os líderes na empresa em estudo. Este instrumento, denominado OCAI (em inglês Organizacional Culture Assessment Instrument), permite diagnosticar o perfil da cultura organizacional e da cultura da qualidade no cenário atual e no contexto ideal, a partir da percepção dos líderes da organização. Para análise dos dados, utiliza-se a técnica de análise de agrupamento, que permite avaliar a homogeneidade das opiniões dos líderes. Os resultados apontam, conforme a visão dos líderes, a necessidade de mudança no perfil cultural organizacional da empresa em estudo, de uma cultura em que predominam elementos da cultura de mercado (cenário atual) para uma cultura com maior ênfase em elementos da cultura clã e inovadora (cenário ideal), bem como uma cultura de qualidade que estimule a inovação, favorável à geração de ideia e conhecimento, a melhoria contínua e a busca por soluções criativas

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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

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The so-called Dual Mode Adaptive Robust Control (DMARC) is proposed. The DMARC is a control strategy which interpolates the Model Reference Adaptive Control (MRAC) and the Variable Structure Model Reference Adaptive Control (VS-MRAC). The main idea is to incorporate the transient performance advantages of the VS-MRAC controller with the smoothness control signal in steady-state of the MRAC controller. Two basic algorithms are developed for the DMARC controller. In the first algorithm the controller's adjustment is made, in real time, through the variation of a parameter in the adaptation law. In the second algorithm the control law is generated, using fuzzy logic with Takagi-Sugeno s model, to obtain a combination of the MRAC and VS-MRAC control laws. In both cases, the combined control structure is shown to be robust to the parametric uncertainties and external disturbances, with a fast transient performance, practically without oscillations, and a smoothness steady-state control signal

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This work present a interval approach to deal with images with that contain uncertainties, as well, as treating these uncertainties through morphologic operations. Had been presented two intervals models. For the first, is introduced an algebraic space with three values, that was constructed based in the tri-valorada logic of Lukasiewiecz. With this algebraic structure, the theory of the interval binary images, that extends the classic binary model with the inclusion of the uncertainty information, was introduced. The same one can be applied to represent certain binary images with uncertainty in pixels, that it was originated, for example, during the process of the acquisition of the image. The lattice structure of these images, allow the definition of the morphologic operators, where the uncertainties are treated locally. The second model, extend the classic model to the images in gray levels, where the functions that represent these images are mapping in a finite set of interval values. The algebraic structure belong the complete lattices class, what also it allow the definition of the elementary operators of the mathematical morphology, dilation and erosion for this images. Thus, it is established a interval theory applied to the mathematical morphology to deal with problems of uncertainties in images

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Conventional control strategies used in shunt active power filters (SAPF) employs real-time instantaneous harmonic detection schemes which is usually implements with digital filters. This increase the number of current sensors on the filter structure which results in high costs. Furthermore, these detection schemes introduce time delays which can deteriorate the harmonic compensation performance. Differently from the conventional control schemes, this paper proposes a non-standard control strategy which indirectly regulates the phase currents of the power mains. The reference currents of system are generated by the dc-link voltage controller and is based on the active power balance of SAPF system. The reference currents are aligned to the phase angle of the power mains voltage vector which is obtained by using a dq phase locked loop (PLL) system. The current control strategy is implemented by an adaptive pole placement control strategy integrated to a variable structure control scheme (VS-APPC). In the VS-APPC, the internal model principle (IMP) of reference currents is used for achieving the zero steady state tracking error of the power system currents. This forces the phase current of the system mains to be sinusoidal with low harmonics content. Moreover, the current controllers are implemented on the stationary reference frame to avoid transformations to the mains voltage vector reference coordinates. This proposed current control strategy enhance the performance of SAPF with fast transient response and robustness to parametric uncertainties. Experimental results are showing for determining the effectiveness of SAPF proposed control system

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The idea of considering imprecision in probabilities is old, beginning with the Booles George work, who in 1854 wanted to reconcile the classical logic, which allows the modeling of complete ignorance, with probabilities. In 1921, John Maynard Keynes in his book made explicit use of intervals to represent the imprecision in probabilities. But only from the work ofWalley in 1991 that were established principles that should be respected by a probability theory that deals with inaccuracies. With the emergence of the theory of fuzzy sets by Lotfi Zadeh in 1965, there is another way of dealing with uncertainty and imprecision of concepts. Quickly, they began to propose several ways to consider the ideas of Zadeh in probabilities, to deal with inaccuracies, either in the events associated with the probabilities or in the values of probabilities. In particular, James Buckley, from 2003 begins to develop a probability theory in which the fuzzy values of the probabilities are fuzzy numbers. This fuzzy probability, follows analogous principles to Walley imprecise probabilities. On the other hand, the uses of real numbers between 0 and 1 as truth degrees, as originally proposed by Zadeh, has the drawback to use very precise values for dealing with uncertainties (as one can distinguish a fairly element satisfies a property with a 0.423 level of something that meets with grade 0.424?). This motivated the development of several extensions of fuzzy set theory which includes some kind of inaccuracy. This work consider the Krassimir Atanassov extension proposed in 1983, which add an extra degree of uncertainty to model the moment of hesitation to assign the membership degree, and therefore a value indicate the degree to which the object belongs to the set while the other, the degree to which it not belongs to the set. In the Zadeh fuzzy set theory, this non membership degree is, by default, the complement of the membership degree. Thus, in this approach the non-membership degree is somehow independent of the membership degree, and this difference between the non-membership degree and the complement of the membership degree reveals the hesitation at the moment to assign a membership degree. This new extension today is called of Atanassov s intuitionistic fuzzy sets theory. It is worth noting that the term intuitionistic here has no relation to the term intuitionistic as known in the context of intuitionistic logic. In this work, will be developed two proposals for interval probability: the restricted interval probability and the unrestricted interval probability, are also introduced two notions of fuzzy probability: the constrained fuzzy probability and the unconstrained fuzzy probability and will eventually be introduced two notions of intuitionistic fuzzy probability: the restricted intuitionistic fuzzy probability and the unrestricted intuitionistic fuzzy probability

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The Oil Measurement Evaluation Laboratory (LAMP), located in the Federal University of Rio Grande do Norte (UFRN), has as main goal to evaluate flow and BS&W meters, where the simulation of a bigger number of operation variable in field, guarantees a less uncertain evaluation. The objective of this work is to purpose a heating system design and implementation, which will control the temperature safely and efficiently in order to evaluate and measure it. Temperature is one of the variables which influence the flow and BS&W accurate measurement, directly affecting the fluid viscosity and density in the experiment. To project the heating system it is of great importance to take the laboratory requirements, conditions and current restrictions into consideration. Three alternatives were evaluated: heat exchanger, internal resistance and external resistance. After the analyses are made in order to choose the best alternative for the heating system in the laboratory, control strategies were determined for it, PID control methods in combination with fuzzy logic were used. Results showed a better performance with fuzzy logic than with classic PID

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In this Thesis, the development of the dynamic model of multirotor unmanned aerial vehicle with vertical takeoff and landing characteristics, considering input nonlinearities and a full state robust backstepping controller are presented. The dynamic model is expressed using the Newton-Euler laws, aiming to obtain a better mathematical representation of the mechanical system for system analysis and control design, not only when it is hovering, but also when it is taking-off, or landing, or flying to perform a task. The input nonlinearities are the deadzone and saturation, where the gravitational effect and the inherent physical constrains of the rotors are related and addressed. The experimental multirotor aerial vehicle is equipped with an inertial measurement unit and a sonar sensor, which appropriately provides measurements of attitude and altitude. A real-time attitude estimation scheme based on the extended Kalman filter using quaternions was developed. Then, for robustness analysis, sensors were modeled as the ideal value with addition of an unknown bias and unknown white noise. The bounded robust attitude/altitude controller were derived based on globally uniformly practically asymptotically stable for real systems, that remains globally uniformly asymptotically stable if and only if their solutions are globally uniformly bounded, dealing with convergence and stability into a ball of the state space with non-null radius, under some assumptions. The Lyapunov analysis technique was used to prove the stability of the closed-loop system, compute bounds on control gains and guaranteeing desired bounds on attitude dynamics tracking errors in the presence of measurement disturbances. The controller laws were tested in numerical simulations and in an experimental hexarotor, developed at the UFRN Robotics Laboratory

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Postsurgical complication of hypertension may occur in cardiac patients. To decrease the chances of complication it is necessary to reduce elevated blood pressure as soon as possible. Continuous infusion of vasodilator drugs, such as sodium nitroprusside (Nipride), would quickly lower the blood pressure in most patients. However, each patient has a different sensitivity to infusion of Nipride. The parameters and the time delays of the system are initially unknown. Moreover, the parameters of the transfer function associated with a particular patient are time varying. the objective of the study is to develop a procedure for blood pressure control i the presence of uncertainty of parameters and considerable time delays. So, a methodology was developed multi-model, and for each such model a Preditive Controller can be a priori designed. An adaptive mechanism is then needed for deciding which controller should be dominant for a given plant

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Conventional control strategies used in shunt active power filters (SAPF) employs real-time instantaneous harmonic detection schemes which is usually implements with digital filters. This increase the number of current sensors on the filter structure which results in high costs. Furthermore, these detection schemes introduce time delays which can deteriorate the harmonic compensation performance. Differently from the conventional control schemes, this paper proposes a non-standard control strategy which indirectly regulates the phase currents of the power mains. The reference currents of system are generated by the dc-link voltage controller and is based on the active power balance of SAPF system. The reference currents are aligned to the phase angle of the power mains voltage vector which is obtained by using a dq phase locked loop (PLL) system. The current control strategy is implemented by an adaptive pole placement control strategy integrated to a variable structure control scheme (VS¡APPC). In the VS¡APPC, the internal model principle (IMP) of reference currents is used for achieving the zero steady state tracking error of the power system currents. This forces the phase current of the system mains to be sinusoidal with low harmonics content. Moreover, the current controllers are implemented on the stationary reference frame to avoid transformations to the mains voltage vector reference coordinates. This proposed current control strategy enhance the performance of SAPF with fast transient response and robustness to parametric uncertainties. Experimental results are showing for determining the effectiveness of SAPF proposed control system

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This work deals with an on-line control strategy based on Robust Model Predictive Control (RMPC) technique applied in a real coupled tanks system. This process consists of two coupled tanks and a pump to feed the liquid to the system. The control objective (regulator problem) is to keep the tanks levels in the considered operation point even in the presence of disturbance. The RMPC is a technique that allows explicit incorporation of the plant uncertainty in the problem formulation. The goal is to design, at each time step, a state-feedback control law that minimizes a 'worst-case' infinite horizon objective function, subject to constraint in the control. The existence of a feedback control law satisfying the input constraints is reduced to a convex optimization over linear matrix inequalities (LMIs) problem. It is shown in this work that for the plant uncertainty described by the polytope, the feasible receding horizon state feedback control design is robustly stabilizing. The software implementation of the RMPC is made using Scilab, and its communication with Coupled Tanks Systems is done through the OLE for Process Control (OPC) industrial protocol

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Fuzzy intelligent systems are present in a variety of equipment ranging from household appliances to Fuzzy intelligent systems are present in a variety of equipment ranging from household appliances to small devices such as digital cameras and cell phones being used primarily for dealing with the uncertainties in the modeling of real systems. However, commercial implementations of Fuzzy systems are not general purpose and do not have portability to different hardware platforms. Thinking about these issues this work presents the implementation of an open source development environment that consists of a desktop system capable of generate Graphically a general purpose Fuzzy controller and export these parameters for an embedded system with a Fuzzy controller written in Java Platform Micro Edition To (J2ME), whose modular design makes it portable to any mobile device that supports J2ME. Thus, the proposed development platform is capable of generating all the parameters of a Fuzzy controller and export it in XML file, and the code responsible for the control logic that is embedded in the mobile device is able to read this file and start the controller. All the parameters of a Fuzzy controller are configurable using the desktop system, since the membership functions and rule base, even the universe of discourse of the linguistic terms of output variables. This system generates Fuzzy controllers for the interpolation model of Takagi-Sugeno. As the validation process and testing of the proposed solution the Fuzzy controller was embedded on the mobile device Sun SPOT ® and used to control a plant-level Quanser®, and to compare the Fuzzy controller generated by the system with other types of controllers was implemented and embedded in sun spot a PID controller to control the same level plant of Quanser®

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An alternative nonlinear technique for decoupling and control is presented. This technique is based on a RBF (Radial Basis Functions) neural network and it is applied to the synchronous generator model. The synchronous generator is a coupled system, in other words, a change at one input variable of the system, changes more than one output. The RBF network will perform the decoupling, separating the control of the following outputs variables: the load angle and flux linkage in the field winding. This technique does not require knowledge of the system parameters and, due the nature of radial basis functions, it shows itself stable to parametric uncertainties, disturbances and simpler when it is applied in control. The RBF decoupler is designed in this work for decouple a nonlinear MIMO system with two inputs and two outputs. The weights between hidden and output layer are modified online, using an adaptive law in real time. The adaptive law is developed by Lyapunov s Method. A decoupling adaptive controller uses the errors between system outputs and model outputs, and filtered outputs of the system to produce control signals. The RBF network forces each outputs of generator to behave like reference model. When the RBF approaches adequately control signals, the system decoupling is achieved. A mathematical proof and analysis are showed. Simulations are presented to show the performance and robustness of the RBF network