Evaluation of thermal stress indexes for dairy cows in tropical regions

Seis ��ndices de estresse ambiental foram aplicados a 1.359 dados de 359 vacas Holandesas e 54 vacas Jersey em rebanhos comerciais do Cear�� e Rio Grande do Norte. O crit��rio de sele����o aplicado aos ��ndices foi sua correla����o com a temperatura retal e a freq����ncia respirat��ria dos animais. O ��ndice de Temperatura e Umidade (THI) e o ��ndice de Globo e Umidade (BGHI) apresentaram os piores resultados, com correla����es muito baixas com as respostas dos animais. Os ��ndices escolhidos foram o ��ndice de Temperatura Equivalente (ESI), correlacionado significativamente com a temperatura retal (r = 0,293) e a freq����ncia respirat��ria (r = 0,520), e o ��ndice de Carga T��rmica (HLI), com correla����es r = 0,286 e r = 0,542 respectivamente.

T��cnicas de simplifica����o de redes e otimiza����o multiobjetivo para an��lise de varia����es de tens��o em regime permanente provocadas por parques e��licos integrados ao sistema el��trico

This study presents a description of the development model of a representation of simplified grid applied in hybrid load flow for calculation of the voltage variations in a steady-state caused by the wind farm on power system. Also, it proposes an optimal load-flow able to control power factor on connection bar and to minimize the loss. The analysis process on system, led by the wind producer, it has as base given technician supplied by the grid. So, the propose model to the simplification of the grid that allows the necessity of some knowledge only about the data referring the internal network, that is, the part of the network that interests in the analysis. In this way, it is intended to supply forms for the auxiliary in the systematization of the relations between the sector agents. The model for simplified network proposed identifies the internal network, external network and the buses of boulders from a study of vulnerability of the network, attributing them floating liquid powers attributing slack models. It was opted to apply the presented model in Newton-Raphson and a hybrid load flow, composed by The Gauss-Seidel method Zbarra and Summation Power. Finally, presents the results obtained to a developed computational environment of SCILAB and FORTRAN, with their respective analysis and conclusion, comparing them with the ANAREDE

Dedu����o de Fun����es de Al��vio para Prioriza����o de Variantes de Chaveamento Adequadas �� Elimina����o de Sobrecargas

Eventually, violations of voltage limits at buses or admissible loadings of transmission lines and/or power transformers may occur by the power system operation. If violations are detected in the supervision process, corrective measures may be carried out in order to eliminate them or to reduce their intensity. Loading restriction is an extreme solution and should only be adopted as the last control action. Previous researches have shown that it is possible to control constraints in electrical systems by changing the network topology, using the technique named Corrective Switching, which requires no additional costs. In previous works, the proposed calculations for verifying the ability of a switching variant in eliminating an overload in a specific branch were based on network reduction or heuristic analysis. The purpose of this work is to develop analytical derivation of linear equations to estimate current changes in a specific branch (due to switching measures) by means of few calculations. For bus-bar coupling, derivations will be based on short-circuit theory and Relief Function methodology. For bus-bar splitting, a Relief Function will be derived based on a technique of equivalent circuit. Although systems of linear equations are used to substantiate deductions, its formal solution for each variant, in real time does not become necessary. A priority list of promising variants is then assigned for final check by an exact load flow calculation and a transient analysis using ATP Alternative Transient Program. At last, results obtained by simulation in networks with different features will be presented

Caracteriza����o de estruturas planares com substratos Iso/Anisotr��picos truncados atrav��s da t��cnica da resson��ncia transversa modificada

This work presents a theoretical and numerical analysis using the transverse resonance technique (TRT) and a proposed MTRT applied in the analysis of the dispersive characteristics of microstrip lines built on truncated isotropic and anisotropic dielectric substrates. The TRT uses the transmission lines model in the transversal section of the structure, allowing to analyze its dispersive behavior. The difference between TRT and MTRT consists basically of the resonance direction. While in the TRT the resonance is calculated in the same direction of the metallic strip normal axis, the MTRT considers the resonance in the metallic strip parallel plane. Although the application of the MTRT results in a more complex equivalent circuit, its use allows some added characterization, like longitudinal section electric mode (LSE) and longitudinal section magnetic mode (LSM), microstrips with truncated substrate, or structures with different dielectric regions. A computer program using TRT and MTRT proposed in this work is implemented for the characterization of microstrips on truncated isotropic and anisotropic substrates. In this analysis, propagating and evanescent modes are considered. Thus, it is possible to characterize both the dominant and higher order modes of the structure. Numerical results are presented for the effective permittivity, characteristic impedance and relative phase velocity for microstrip lines with different parameters and dimensions of the dielectric substrate. Agreement with the results obtained in the literature are shown, as well as experimental results. In some cases, the convergence analysis is also performed by considering the limiting conditions, like particular cases of isotropic materials or structures with dielectric of infinite size found in the literature. The numerical convergence of the formulation is also analyzed. Finally, conclusions and suggestions for the continuity of this work are presented

An��lise dos Modos Ressonantes em Antenas de Microfita sobre Substratos Iso/Anisotr��picos por T��cnicas da Resson��ncia Transversa

Neste trabalho, s��o utilizadas a T��cnica da Resson��ncia Transversa (TRT) e a T��cnica da Resson��ncia Transversa Modificada (MTRT), para a determina����o das freq����ncias dos modos ressonantes de antenas de microfita com patch quadrado, retangular e circular e com substratos isotr��picos e anisotr��picos. Para isso, �� proposto um modelo da cavidade equivalente, onde a antena tipo patch retangular �� representada como sendo a superposi����o de duas linhas infinitas em microfita, uma de largura W, representando a dimens��o que expressa a largura do patch, e a outra com largura L, representando a dimens��o que expressa o comprimento do patch. A avalia����o da efici��ncia e aplicabilidade dos m��todos citados �� realizada comparando-se com resultados experimentais e obtidos atrav��s de outras t��cnicas. Tr��s situa����es ser��o verificadas: estruturas com substrato infinito, estrutura com substrato tipo pedestal e estruturas com substrato truncado al��m dos limites da fita met��lica. Os resultados obtidos demonstram que as t��cnicas de an��lise de onda completa utilizadas neste trabalho, por um formalismo matem��tico mais rigoroso, s��o eficientes e precisas tanto na aplica����o em estruturas com substrato isotr��pico como nas que possuem substrato anisotr��pico. Inicialmente s��o consideradas apenas as estruturas com substratos isotr��picos, com diferentes constantes diel��tricas, e �� avaliada a influ��ncia da largura do substrato sobre as freq����ncias dos modos ressonantes das antenas. Posteriormente, a an��lise do truncamento do diel��trico �� realizada para estruturas com substrato anisotr��pico. Em todos os casos, os resultados experimentais, obtidos a partir da constru����o de prot��tipos, s��o confrontados com os obtidos a partir de simula����o, utilizando as t��cnicas TRT e MTRT. No final, as t��cnicas descritas s��o utilizadas para antenas tipo patch circular, sendo utilizada uma t��cnica de equival��ncia para transformar a antena circular em outra quadrada ou retangular equivalente, dependendo do modo que se queira encontrar. Os resultados obtidos s��o ent��o analisados, observando-se uma boa concord��ncia e indicando a viabilidade do m��todo. Ap��s isso, s��o apresentadas as conclus��es e sugeridos alguns temas para a continuidade deste trabalho

Um algoritmo para estima����o de estado em alimentadores de distribui����o de energia el��trica com base no m��todo da soma de pot��ncias

Most algorithms for state estimation based on the classical model are just adequate for use in transmission networks. Few algorithms were developed specifically for distribution systems, probably because of the little amount of data available in real time. Most overhead feeders possess just current and voltage measurements at the middle voltage bus-bar at the substation. In this way, classical algorithms are of difficult implementation, even considering off-line acquired data as pseudo-measurements. However, the necessity of automating the operation of distribution networks, mainly in regard to the selectivity of protection systems, as well to implement possibilities of load transfer maneuvers, is changing the network planning policy. In this way, some equipments incorporating telemetry and command modules have been installed in order to improve operational features, and so increasing the amount of measurement data available in real-time in the System Operation Center (SOC). This encourages the development of a state estimator model, involving real-time information and pseudo-measurements of loads, that are built from typical power factors and utilization factors (demand factors) of distribution transformers. This work reports about the development of a new state estimation method, specific for radial distribution systems. The main algorithm of the method is based on the power summation load flow. The estimation is carried out piecewise, section by section of the feeder, going from the substation to the terminal nodes. For each section, a measurement model is built, resulting in a nonlinear overdetermined equations set, whose solution is achieved by the Gaussian normal equation. The estimated variables of a section are used as pseudo-measurements for the next section. In general, a measurement set for a generic section consists of pseudo-measurements of power flows and nodal voltages obtained from the previous section or measurements in real-time, if they exist -, besides pseudomeasurements of injected powers for the power summations, whose functions are the load flow equations, assuming that the network can be represented by its single-phase equivalent. The great advantage of the algorithm is its simplicity and low computational effort. Moreover, the algorithm is very efficient, in regard to the accuracy of the estimated values. Besides the power summation state estimator, this work shows how other algorithms could be adapted to provide state estimation of middle voltage substations and networks, namely Schweppes method and an algorithm based on current proportionality, that is usually adopted for network planning tasks. Both estimators were implemented not only as alternatives for the proposed method, but also looking for getting results that give support for its validation. Once in most cases no power measurement is performed at beginning of the feeder and this is required for implementing the power summation estimations method, a new algorithm for estimating the network variables at the middle voltage bus-bar was also developed

Uso de t��cnicas de otimiza����o baseadas em derivadas como suporte do planejamento operacional de redes de distribui����o de energia el��trica

The usual programs for load flow calculation were in general developped aiming the simulation of electric energy transmission, subtransmission and distribution systems. However, the mathematical methods and algorithms used by the formulations were based, in majority, just on the characteristics of the transmittion systems, which were the main concern focus of engineers and researchers. Though, the physical characteristics of these systems are quite different from the distribution ones. In the transmission systems, the voltage levels are high and the lines are generally very long. These aspects contribute the capacitive and inductive effects that appear in the system to have a considerable influence in the values of the interest quantities, reason why they should be taken into consideration. Still in the transmission systems, the loads have a macro nature, as for example, cities, neiborhoods, or big industries. These loads are, generally, practically balanced, what reduces the necessity of utilization of three-phase methodology for the load flow calculation. Distribution systems, on the other hand, present different characteristics: the voltage levels are small in comparison to the transmission ones. This almost annul the capacitive effects of the lines. The loads are, in this case, transformers, in whose secondaries are connected small consumers, in a sort of times, mono-phase ones, so that the probability of finding an unbalanced circuit is high. This way, the utilization of three-phase methodologies assumes an important dimension. Besides, equipments like voltage regulators, that use simultaneously the concepts of phase and line voltage in their functioning, need a three-phase methodology, in order to allow the simulation of their real behavior. For the exposed reasons, initially was developped, in the scope of this work, a method for three-phase load flow calculation in order to simulate the steady-state behaviour of distribution systems. Aiming to achieve this goal, the Power Summation Algorithm was used, as a base for developping the three phase method. This algorithm was already widely tested and approved by researchers and engineers in the simulation of radial electric energy distribution systems, mainly for single-phase representation. By our formulation, lines are modeled in three-phase circuits, considering the magnetic coupling between the phases; but the earth effect is considered through the Carson reduction. Its important to point out that, in spite of the loads being normally connected to the transformers secondaries, was considered the hypothesis of existence of star or delta loads connected to the primary circuit. To perform the simulation of voltage regulators, a new model was utilized, allowing the simulation of various types of configurations, according to their real functioning. Finally, was considered the possibility of representation of switches with current measuring in various points of the feeder. The loads are adjusted during the iteractive process, in order to match the current in each switch, converging to the measured value specified by the input data. In a second stage of the work, sensibility parameters were derived taking as base the described load flow, with the objective of suporting further optimization processes. This parameters are found by calculating of the partial derivatives of a variable in respect to another, in general, voltages, losses and reactive powers. After describing the calculation of the sensibility parameters, the Gradient Method was presented, using these parameters to optimize an objective function, that will be defined for each type of study. The first one refers to the reduction of technical losses in a medium voltage feeder, through the installation of capacitor banks; the second one refers to the problem of correction of voltage profile, through the instalation of capacitor banks or voltage regulators. In case of the losses reduction will be considered, as objective function, the sum of the losses in all the parts of the system. To the correction of the voltage profile, the objective function will be the sum of the square voltage deviations in each node, in respect to the rated voltage. In the end of the work, results of application of the described methods in some feeders are presented, aiming to give insight about their performance and acuity

Compara����o entre modelos equivalentes de aerogeradores s��ncronos utilizando o programa ATP

At present, the electricity generation through wind energy has an importance growing in the world, with the existence of very large plans for future wind power installation worldwide. Thus, the increasing the electricity generation through wind power requires, more and more, analysis of studies of interaction between wind parks and electric power systems. This paper has as purposes to implement equivalent models for synchronous wind generators to represent a wind park in ATP program and to check behavior of the models through simulations. Simulations with applications of faults were achieved to evaluate the behavior of voltages of system for each equivalent model, through comparisons between the results of models proposed, to verify if the differences obtained allows the adoption of the simplest model

An��lise de superf��cies seletivas de freq����ncia para aplica����es em ondas milim��tricas

This work consists in the development of a theoretical and numerical analysis for frequency selective surfaces (FSS) structures with conducting patch elements, such as rectangular patches, thin dipoles and cross dipoles, on anisotropic dielectric substrates. The analysis is developed for millimeter wave band applications. The analytical formulation is developed in the spectral domain, by using a rigorous technique known as equivalent transmission line method, or immitance approach. The numerical analysis is completed through the use of the Galerkin's technique in the Fourier transform domain, using entire-domain basis functions. In the last decades, several sophisticated analytical techniques have been developed for FSS structure applications. Within these applications, it can be emphasized the use of FSS structures on reflecting antennas and bandpass radomes. In the analysis, the scattered fields of the FSS geometry are related to the surface induced currents on the conducting patches. After the formulation of the scattering problem, the numerical solution is obtained by using the moment method. The choice of the basis functions plays a very important role in the numerical efficiency of the numerical method, once they should provide a very good approximation to the real current distributions on the FSS analyzed structure. Thereafter, the dyadic Green's function components are obtained in order to evaluate the basis functions unknown coefficients. To accomplish that, the Galerkin's numerical technique is used. Completing the formulation, the incident fields are determined through the incident potential, and as a consequence the FSS transmission and reflection characteristics are determined, as function of the resonant frequency and structural parameters. The main objective of this work was to analyze FSS structures with conducting patch elements, such as thin dipoles, cross dipoles and rectangular patches, on anisotropic dielectric substrates, for high frequency applications. Therefore, numerical results for the FSS structure main characteristics were obtained in the millimeter wave bando Some of these FSS characteristics are the resonant

Implanta����o de um sistema de detec����o de vazamentos em oleodutos com tratamento de alarmes falsos

The pumping of fluids in pipelines is the most economic and safe form of transporting fluids. That explains why in Europe there was in 1999 about 30.000 Km [7] of pipelines of several diameters, transporting mill��ons of cubic meters of crude oil end refined products, belonging to COCAWE (assaciation of companies of petroleum of Europe for health, environment and safety, that joint several petroleum companies). In Brazil they are about 18.000 Km of pipelines transporting millions of cubic meters of liquids and gases. In 1999, nine accidents were registered to COCAWE. Among those accidents one brought a fatal victim. The oil loss was of 171 m3, equivalent to O,2 parts per million of the total of the transported volume. Same considering the facts mentioned the costs involved in ao accident can be high. An accident of great proportions can br��ng loss of human lives, severe environmental darnages, loss of drained product, loss . for dismissed profit and damages to the image of the company high recovery cost. In consonance with that and in some cases for legal demands, the companies are, more and more, investing in systems of Leak detection in pipelines based on computer algorithm that operate in real time, seeking w��th that to minimize still more the drained volumes. This decreases the impacts at the environment and the costs. In general way, all the systems based on softWare present some type of false alarm. In general a commitment exists betWeen the sensib��lity of the system and the number of false alarms. This work has as objective make a review of th�� existent methods and to concentrate in the analysis of a specific system, that is, the system based on hydraulic noise, Pressure Point Analyzis (PPA). We will show which are the most important aspects that must be considered in the implementation of a Leak Detection System (LDS), from the initial phase of the analysis of risks passing by the project bases, design, choice of the necessary field instrumentation to several LDS, implementation and tests. We Will make na analysis of events (noises) originating from the flow system that can be generator of false alarms and we will present a computer algorithm that restricts those noises automatically

Viabilidade t��cnica e econ��mica da substitui����o de fontes convencionais de energia por biog��s em assentamento rural do Estado de S��o Paulo

O objetivo deste estudo foi avaliar a viabilidade econ��mica da implanta����o de dois biodigestores com uso de dejetos animais em ��rea do Assentamento de Trabalhadores Rurais no munic��pio de Itaber�� - SP, no ano de 2005; um deles para o fornecimento de energia para os domic��lios e outro para as atividades produtivas. Foram avaliados os benef��cios referentes ao fornecimento de energia el��trica e t��rmica, a partir do biog��s, para cinco domic��lios da agrovila do assentamento e para as atividades produtivas, comparativamente aos custos de constru����o e opera����o para produ����o de biog��s. Os resultados mostraram a viabilidade econ��mica da produ����o de g��s em ambos os biodigestores. Foram gerados benef��cios no valor de R$ 3.698,00 por ano e R$ 9.080,57 por ano, nos biodigestores para os domic��lios e produ����o, respectivamente; bem como o equivalente a R$ 1.478,28 por ano referentes �� produ����o de biofertilizante. O custo anual do processo �� de R$ 1.218,50 em cada biodigestor. O prazo de recupera����o do investimento �� de 2,5 anos e 11 meses, para a produ����o de biog��s nos domic��lios e na produ����o, respectivamente. Os resultados podem ser utilizados para subsidiar pol��ticas p��blicas direcionadas ao aproveitamento de biomassa para a produ����o de energia a baixos custos no segmento da agricultura familiar.

An��lise de linhas de fita n��o-homog��neas com camadas diel��tricas anisotr��picas

Abstract

Reconhecimento de padr��es de falhas em motores trif��sicos utilizando redes neurais

This work presents a diagnosis faults system (rotor, stator, and contamination) of three-phase induction motor through equivalent circuit parameters and using techniques patterns recognition. The technology fault diagnostics in engines are evolving and becoming increasingly important in the field of electrical machinery. The neural networks have the ability to classify non-linear relationships between signals through the patterns identification of signals related. It is carried out induction motor��s simulations through the program Matlab R & Simulink R , and produced some faults from modifications in the equivalent circuit parameters. A system is implemented with multiples classifying neural network two neural networks to receive these results and, after well-trained, to accomplish the identification of fault��s pattern

SAMVC sistema de autoria de museus virtuais colaborativos

The use of graphical objects three-dimensional (3D) multimedia applications is gaining more space in the media. Networks with high transmission rates, computers with large processing and graphics boost and popularize such three-dimensional applications. The areas of 3D applications ranging from military applications, entertainment applications geared up for education. Within the applications related to education, we highlight the applications that create virtual copies of cultural spaces such as museums. Through this copy, you can virtually visit a museum, see other users, communicate, exchange information on works, etc. Thereby allowing the visit museums physically distant remote users. A major problem of such virtual environments is its update. By dealing with various media (text, images, sounds, and 3D models), its subsequent handling and update on a virtual environment requires staff with specialized knowledge. Speaking of museums, they hardly have people on your team with this profile. Inside the GT-MV (Grupo de Trabalho de Museus Virtuais), funded by RNP (Rede Nacional de Ensino e Pesquisa) propose a portal for registration, amendment and seen collaborative virtual museums of Brazil. The update, be it related to work or physical space, a system with a national scale like this, would be impossible if done only by the project team. Within this scenario, we propose the modeling and implementation of a tool that allows editing of virtual spaces in an easy and intuitive as compared with available tools. Within the context of GT-MV, we apply the SAMVC (Sistema de Autoria de Museus Virtuais Colaborativos) to museums where curators build the museum from a 3D floor plan (2D). The system, from these twodimensional information, recreates the equivalent in three dimensions. With this, through little or no training, team members from each museum may be responsible for updating the system

An��lise de onda completa de superf��cie seletiva em freq����ncia do tipo anteparo duplo

This work presents a theoretical analysis and numerical and experimental results of the scattering characteristics of frequency selective surfaces, using elements of type patch perfectly conductor. The structures are composed of two frequency selective surfaces on isotropic dielectric substrates cascaded, separated by a layer of air. The analysis is performed using the method of equivalent transmission line in combination with the Galerkin method, to determine the transmission and reflection characteristics of the structures analyzed. Specifically, the analysis uses the impedance method, which models the structure by an equivalent circuit, and applies the theory of transmission lines to determine the dyadic Green's function for the cascade structure. This function relates the incident field and surface current densities. These fields are determined algebraically by means of potential incidents and the imposition of the continuity of the fields in the dielectric interfaces. The Galerkin method is applied to the numerical determination of the unknown weight coefficients and hence the unknown densities of surface currents, which are expanded in terms of known basis functions multiplied by these weight coefficients. From the determination of these functions, it becomes possible to obtain numerical scattered fields at the top and bottom of the structures and characteristics of transmission and reflection of these structures. At work, we present numerical and experimental results for the characteristics of transmission and reflection. Comparisons were made with other results presented in literature, and it was observed a good agreement in the cases presented suggestions continuity of the work are presented