RCAAP Repository

This dissertation focuses the importance of registering eventual frequency variations in Electric Power System which may cross the established limits for normal operation. These can cause serious problems in the operation of sensitive equipments connected to the electric grid, such as the turbo-generators employed in thermoelectric plants. For power system frequency supervision it is used frequency relays which act on protection devices when abnormal conditions are detected. In this context, the major objectives of this work consist of proposing the implementation of an algorithm capable of detecting frequency disturbances characterized by under or over frequency situations and quantifying the time during which the system was operating in such conditions. To achieve this objective the wavelet technique called multiresolution analysis was used for detection of generated disturbances. The data obtained can then be treated in order to prepare a predictive maintenance, mainly in steam turbines which are equipments more subject to damages when in long lasting operation under abnormal frequency conditions.

Conselho Nacional de Desenvolvimento Científico e Tecnológico

This work presents a multi-dimensional similarity modeling strategy and relevance feedback technique for minimizing the semantic gap intrinsic problem of CBIR systems by allowing users to customize their queries according to their requirements and preferences. We propose a composite strategy using a multi-dimensional, vectorial, spatially clustered, and relevance-ordered approach. Given a set of k features which represents the elements in an image database, the similarity measure between a query image and another from the image collection is analyzed in k components, and the images are ranked on a k dimensional space according to their projections over the axis xn, where n = 1, 2, ... k. System experimentation was executed thoroughly using a test image database containing up to 20,000 pictures. The experimental results have shown that the presented approach can substantially improve the outcome in image retrieval systems.

There is great concern by the power systems utilities related to disturbances that generate induced overvoltages in the power network, as they reach the consumer sensitive equipment, causing damage and losses. In consequence of this framework, the power systems utilities get large financial losses every year due to indemnity for damage to such equipments. Among the disturbances that lead to induced overvoltages are lightning. Thus, in this work it was developed the study and analysis of the lightning´s effect on loads allocated on average (11kV/15kV) and low voltage (below 600V) under the influence caused by the resistance of grounding. For modeling and simulation of the system under analysis, the program for transient study ATP (Alternative Transient Program) was used. To develop the study, it was designed a system comprising of an 88kV transmission line, a substation, a distribution line of 13.8 kV and loads representing residential consumers. It was also analyzed the use of surge suppressor in the low voltage distribution transformers as a way to mitigate the induced overvoltages that reach consumers.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Elderly people are the individuals who are more affected by tremor and its consequences, responsible for individual s physical and social deterioration. In the current context, the elderly represents a great parcel of world-wide population, that suffered a great increase in the last past years. As the tremor can represent an indication of complex syndromes, its study is of great impact and importance, because the results of such studies may, improve the quality of life of individuals reducing therefore related social and economical costs. The main aim of this research was to seek for features extracted from electromyographic signals that can be used in the analysis of the relation between physiological tremor and ageing. For this, the electromyographic activity of groups of subjects from different ages, without neurologic dysfunctions and without the use of any drugs that can amplify or attenuate the tremor, it was collected by means of the execution of three distinct experimental protocols, being the same based on neurological tests that employs the spiral of Archimedes. The data analysis consisted on the evaluation of features extracted from the electromyographic activity, and on the characterization of the statistical properties of this features by means of the statistical technique called Bootstrap. The results showed that in general it is quite complex to characterize the relationship between tremor and electromyography through the features investigated, but trends were observed that may be related to physiological changes of groups from different ages.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

By means of computing simulations, it is presented in this work a comparative study of the effects of electromagnetic transients proceeding from indirect and direct atmospheric discharges in mixed-transmission lines, which consist of aerial and underground parts with oil and dry type isolation. The developed and implemented model in the ATP computing environment was based on a part of AES- Eletropaulo subtransmission system compounded of Bandeirante substation and Morumbi, Granja Julieta and Alto da Boa Vista distribution stations. The data of the considered equipment were first obtained through a R&D project regarding the effects of atmospheric discharges in Distribution and Transmission Stations developed for energy distribution company AES-Eletropaulo by Uberlândia Federal University and Santa Cecília University. Thus, equipment equivalent models development was done individually and based on real data. Data input consistency checking was based on either measured or theoretical values, depending on the information available. The equivalent electric system configurations used in simulations were determined by several combinations which considered the alternance of parameters, such as: types of cable, use of lightning rods and kind of cables installations (kept unmodified in relation to the rest of the system). In relation to transients effects attenuation, the main results found were the following: better results of oil cables than that of dry cables; small influence of systemic alterations of the electric distribution stations; efficiency of lightning rods usage in this type of system and small variations for the provision of cables.

This paper presents an analysis study about the induction machine, operating as a generator directly connected to the electrical power grid. One of the main characteristics of the generator operation is to work in zones distinctly from its rated power, supplying a variety of loads with different demands of power. When working on the saturation region, the induction machine generates currents with distorted wave forms. Intending to analyze such distortions, an adequate computational modeling, considering the magnetic saturation effects is employed. Experimental tests were made with a real machine for theoretical-experimental confrontation purposes. For a wide band of operation and generate power, the currents, voltages, power and velocity are analyzed, revealing the operational characteristics of the generator induction machine.

Virtual Reality is a computational technique that allows user interactio n, immersion and navigation in virtual environments that simulates real life. Because of this reason, its use in several areas of the knowledge is very promising, especially in Psychology, in phobia treatment. For driving phobia treatment, these features can also bring benefits. There are several systems that use Virtual Reality for driving phobia treatment. In these systems, the patient covers virtual routes with elements that cause him this phobia. These systems, however, sin for not offering flexibility to the psychologist in the creation of routes, becoming the treatment limited to previously constructed routes, that nor always reveal adequate for the fears presented for the patients. This research shows the development of a route creation system to be used in driving phobia treatment, built to follow two basic principles: provide high flexibility to the psychologist, so he has freedom to create customized routes, according to each patient s profiles, and have a simple and intuitive interface, minimizing difficulties on the construction of these routes. Besides, this system maps a constructed 2D route to a virtual environment, automatically and transparent, excusing knowledge of computational techniques related to these operations. This interface makes possible to the psychologist choose amongst common objects, found on the traffic of cities, and locate them according to his necessities. Moreover, it allows that external conditions to the route to be configured, such as climatic and traffic conditions. The system was evaluated by a group of psychologists, whose majority did not have difficulties in using the system, and considered the process of construction of routes simple and intuitive. At the end, a series of future works is presented, that configures as functionalities to be added or modified on the system, conferring to it bigger efficiency in its function.

This work deals with the study, design and implementation of fluorescent dimming ballast. The adopted ballast consists in a half bridge integrated with a boost converter to provide power factor correction. Three dimming techniques was studied, frequency variation, duty cycle variation and the combination between frequency and duty cycle variation. Simulation and experimental results are presented.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The usage of specific databases for certain application does not allow the replacement of database or sharing information with other databases by user, without rebuilding the entire application, turning non-trivial the application of the solutions proposed in the literature. This reduces the interoperability among different suppliers of present biomedical data. This paper describes the design and development of a system for interface and management of biomedical signals databases. The system s features includes the use of different databases and the storage of the data for further analysis and was designed using the object-oriented technique, plug-ins and reflection technique, leading to create an application capable of connecting with the different databases. The developed system has capability of storage biomedical information, through the use of adaptive systems and plug-ins, reducing the problems of lack of compatibility between data banks, difficulties in maintenance and integration among them. The experiment results showed that the framework is able to collect patients biomedical data, that may be registered with their clinical features, and interact with differentdatabases.

The objective of this thesis is to present a methodology of comparison of the electric, mechanical and hydraulical performance of a pump system, under the point of view of the energy efficiency, when supplied with signals power quality. The form used for this intention was to the variation of controlled outflow for strangulation of valve or variation of frequency applying Adjustable Speed Drive (ASD). The parameters had been compared in the presence of supply with sinusoidal symmetrical voltage balanced, anti-symmetrical unbalanced and voltage with harmonic distortion. The operation of the system was carried through by three phase induction motor of high efficiency. It is still present in this work, the computational simulation in the time domain. The used computational platform for this end was ATP (Alternative Transient Program). The form used for validation of the modeling, concentrated in the comparison of the values found in the assays and the gotten ones through the simulations. The laboratory experiments had been executed in the laboratory of energy efficiency of the Faculty of Electrical Engineering of the Federal University of Uberlândia.

The amount of medical images is growing, and in hospitals and clinics, where the number of patients is high, the space requested for all those information is very big, and that becomes a problem. One of the ways to reduce this problem is to compress those images. The aim of this work is to obtain one quantization matrix for ultrasonic echo images and magnetic resonance using the arithmetic average method. This matrix should provide a small rate of bits/pixel and a satisfactory quality for the medical diagnosis of those images. In order to obtain that quantization matrix were found four quantization matrix from Q2 to Q5, obtained through the use of five ultrasonic echo images and 454 magnetic resonance images. The results obtained in the tests of this work showed that from the quantization matrix Q2 to Q5 obtained in this dissertation, one that presented the smallest rate of bits/pixel was the Q5 with value equals to 0,38081. This rate is 29 % smaller than the rate of bits/pixel of the matrix Q6 (matrix obtained by Hamamoto for ultrasonic echo images) whose value is equal to 0,53638 and 37,55 % smaller than the rate of bits/pixel of the matrix Q1 (quantization matrix of the pattern JPEG) whose value is equal to 0,61141. By the fact that the percentile differences of PSNRs of the matrix Q2 to Q6 in relation to PSNR of the matrix Q1 are smaller than 10 % and that the six consulted doctors' opinion on the quality of the ultrasonic echo images and resonance magnetic reconstructed using the matrix of Q1 to Q6 are satisfactory for them to accomplish their diagnoses, it can be considered that those images present the same quality. Therefore, the quantization matrix Q5 can be considered as being the quantization matrix optimized for those images, because it presents a small rate of bits/pixel and a satisfactory quality.

This work presents a high performance digital controller of a single phase PWM sinusoidal inverter, using a 16-bits fixed point DSP. This converter is typically used in UPS (Uninterruptible Power Supplies), where a sinusoidal output voltage is desired. The digital controller has an internal filter capacitor current loop, and an external output voltage loop. Experimental results showing the performance of the system under linear and non-linear loads are presented, where a low total harmonic distortion (THD) is achieved.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Parafunctional dental clenching or bruxism may be related to clinical cases of Temporomandibular Disorders (TMD), an etiological factor which sustains the disease of paramount importance. The aim of this study was to develop a protocol of myofeedback therapy and evaluate its application in patients with orofacial pain of muscular origin triggered by parafunctional dental clenching. A total of 10 female patients were submitted to the anamnesis and the intra and extra oral clinical exam, followed by filling in a Clinical Index of Fonseca (1994), which classified 50% of patients with moderate dysfunction and 50% severe. It was applied the Visual Analogue Scale (VAS) to measure pain intensity and performed the evaluation of electromyographic activity of masseter muscle during clenching (maximum voluntary contraction), at dental contact and at rest, in an initial period, after therapy by myofeedback and 30 days of follow-up. The results obtained at the end of treatment and after 30 days of monitoring demonstrated that the patients had reduced levels of pain in 100% of the individuals and an increase in electromyographic activity of masseter muscle in 80% of the cases. Therefore, it was shown that the miofeedback therapy can reduce the painful symptoms and also interfere with muscle activity, contributing to an improvement in the overall clinical picture presented by patients with orofacial pain occasioned by dental clenching.

The aim of this work was the development of a system based on images acquisition that assists in the training and in the biomechanics analysis of the athletes, specifically, of swimmers. The analysis focused at identification and the quantification of the biomechanical factors that can improve the performance of swimmers, because the optimization of small values can mean the victory in swimming. For the biomechanics evaluation is necessary to know some parameters of a swimmer, such as partial speed and average speed of the swim, stroke frequency and length, rhythm of swim, mensurement of articular angles, among others. So that these data represent faithfully athlete's values, without limiting their actions with equipment coupled to then, the system denominated SABIO is divided into hardware and software. The hardware is composite for several elements like as video cameras, pool signs and system of visual stimulus and it has the function of capture images of the swim in the plan sagital of the athlete, defining interest points in environment and in the swimming pool and to dictate the test rhythm. The software fulfills the calculations of the swim parameters and the biomechanics analysis of the swimmers. They were accomplished several tests, with athletes of distinct modalities in all development stages of the system, for adjustment of the materials involved in the hardware. For validation of the SABIO, it was studied the kinematics aspect of the movements of an athlete. The results obtained by the system ware expected and allowed to analyze the wished factors.

It is well known that the electrical energy transmission procedures make use of traditional overhead lines. The operation performances of these lines are strongly dependent on their equivalent inductances and capacitances which are strictly tight to the concept of reactive energy consumption and generation. Due to the relationship between this type of energy and the operational voltage levels, it is quite straightforward that the voltage quality standards are directly linked to the constructive characteristics of the overhead lines. Within this context and considering the main target of this dissertation, focusing the optimization of transmission energy procedures without ignoring the voltage quality matters, the present research makes use of a modern technical approach based on Genetic Algorithm (GA) to look for the best physical arrangement for a given transmission line, without forgetting the power quality requirements. In addition to an introductory chapter related to classical principles leading to the line equivalent inductances and capacitances, the methods to cope with optimization processes are described with emphasis to the mentioned GA. Using this approach, a computational program is obtained and tests are conduct to highlight its application. Two distribution lines are considered a 34.5 and a 138 kV line. Throughout these examples the software potentiality is clearly shown and the gains on power transmissibility are illustrated.