Repositório RCAAP

The comparative study of electric machines has been in vogue due to the growing demand for electromechanical converters with maximum possible efficiency. In this scene, the switched reluctance machines have proven to be competitive. Comparative studies between these machines and the already established induction machines can be easily found in the scientific literature, but studies on various configurations of the switched reluctance machines are not as widespread. This work shows the modeling, simulation and presents a comparative study of two Switched Reluctance Machines to a single phase (6x6) and three-phase (6x4). Aspects of construction, drive and efficiency are discussed in order to find advantages and disadvantages to each of these machines.

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This work presents the development and the experimental analysis of a new single-phase hybrid rectifier with high power factor (PF) and low harmonic distortion of current (THDI), suitable for high power application. The proposed structure is composed by an ordinary single-phase diode rectifier with parallel connection of a switched converter. It is outlined that the switched converter is capable of composing the input line current waveform assuring high PF and low THDI. However, the power rating of the switched converter is lesser than 50% of the total output power, assuring robustness and reliability for the proposed hybrid rectifier. Two prototypes rated at 1 kW and 10 kW were developed and analyzed in laboratory, using digital control technique. A PWM control strategy was implemented imposing quasi-sinusoidal line input current waveform and limiting the switched converter power contribution. It was found that the line input current harmonic spectrum is in accordance with the harmonic limits imposed by IEC61000-3-2 and IEC61000-3-4. The principle of operation, the mathematical analysis, and experimental results from a 1 kW and 10 kW prototypes are also presented in this work.

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Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The study of lightning and the resulting induced voltages is very important in the process of designing of transmission lines. In this work it will be presented problems that can be caused by such phenomenon in electrical systems, as a consequence of these voltages peaks. A analysis of the characterization of atmospheric discharge is performed in order to understand causes of induced overvoltages in transmission lines. Will be presented the classical methodology and a new proposal to estimate the tower surge impedance. In the new developed technique was used the finite element method, to obtain a computational model of the transmission tower, so as to simplify the studies. For the calculation of induced overvoltages, it was used the classic methodology developed by Sune Rusck, which is highly regarded and used for such propose. Based on the Rusck s theory, a computational model of induced voltages in transmission lines was implemented in EMTP/ ATPDraw environment, which it is a software developed by Hermann W. Dommel, with great application in evaluation of electromagnetic transients in power systems. From the model developed, results were obtained of induced voltages which are compared with measurements made by P. P. Barker, for checking and adjustment. Furthermore, propagation analysis of induced voltages on transmission lines were made, as well as the influence of some parameters in its amplitude and waveform.

We have developed and created a simulator for calculations and indicatios of maximum permissible values for the electric and magnetic fields as well as the power density in Rádio Base Station, with the use of CDMA technology, in the range of 800 MHz, being the values allowable were referenced and based on the International Commission on Non-ionizing radiation protection. The simulator developed allows to calculate the interference field radiated by rádio base station, with input data such as channel power rádio; Gain Antenna; Number of Rádio Channels, Frequency Operation; Losses in Cable, Attenuation of Direction; Minimum distance; Reflections. To get quickly without the need for the implementation of instruments for measurements, calculations only in that simulator, we calculated values such as: Effective Radiated Power; Density Power Sector; electric field in the Sector; Magnetic Field in the sector; Flux Density Magnetic; point of maximum permissible exposure to electric field and the power density. As results presented in graphs for clarity of visualization of power density in the industry, as well as defining the coverage area. Is also present in the simulator, folders with specifications of antennas, towers and cables used in mobile phones, whose manufacturers are: World RFS, Andrew, and Karthein Brasilsat. They are presented several "links" network access "internet" to complement the specifications of cables, antennas, etc. .. Moreover also part of the simulator to perform calculations quickly and safely assisting in obtaining results of loss of rádio signal generated by rádio base station. Where the simulator has paintings depicting the spreads, where we define propagation "A" and "B".By spreading the "A" we can get the calculations of rádio signal attenuation models in areas of urban, dense urban, suburban, and rural open. Are added in the calculations of reflection coefficients of reflection, the standing wave ratio, return loss, the ratio of reflected power, as well as losses of the signal by impedance mismatch. As for the spread "B" as we can get results in the loss calculations in the rádio signal line in sight and no sight, the effective area, the power density, the power received, the range, the level conversion and the conversion gain in radiant systems.

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Although the Bandwidth Broker has been proposed with the objective to give more intelligence to DiffServ networks, allowing the allocation of resources in a dynamic way for applications, once the resources are granted they remain statically allocated along the requested period. In this article, we propose an enhanced resource allocation mechanism, based on the fact that the instantaneous traffic load of the applications are generally dynamic in nature, and consequently, the required bandwidth is less than the allocated bandwidth during some periods. Simulation results demonstrated that the proposed mechanism yields better resource utilization while respecting limits of drop of packets and end-to-end delay.

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This dissertation presents the development of a system of authority in Augmented Reality, to aid the development of teaching materials aimed at vocational education, focusing on a dedicated interface for users not experienced in programming. Considering related work, it was found that the authorship related systems have the interface built on heterogeneous groups of users, which often hampers its use as it is first necessary to understand the technology and only after the development of tasks. Therefore, we propose an authoring system built with the effective participation of users, regarding the interface and the tasks that should enable. To validate this research, we chose a case study that represents a specific area of professional education, in this case, motor mechanics. Once developed, the material is applied to the evaluation of a group of ten students, by means of objective and subjective issues related to the component. Another class, the same course, studied the same component, but with conventional teaching materials. Subsequently, we applied this group the same questions, in order to distinguish possible contributions of the strategy developed using Augmented Reality. For validation of the user interface was based on a questionnaire ISONORM 9126 - NBR 13596, which provides a model of six characteristics and software quality sub characteristics after tabulated it was found that most users were very satisfied with the developed interface.

Conselho Nacional de Desenvolvimento Científico e Tecnológico

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The Biomedical Engineering, through its subspecialties, such as the Clinical Engineering and Hospital Engineering was incorporated permanently into the lives of health institutions, as with the advancement of technology and the definitive inclusion of medical equipment as a means of diagnosis and therapy, has become essential to these organizations. The activities developed by the Clinical Engineering in healthcare facilities are based on engineering knowledge and the manage applied to health technologies. In this context, this research aimed to study and report the impact of the application of management techniques in Clinical Engineering at the UFU Clinical Hospital, a large university hospital and reference for high complexity. This is a case studied, a quantitative, considering an economic and quality evaluation, which was used the documental research as technical procedure. It was analyzed data in reports and administrative documents from the hospital at the period 2001 to 2010, related to human resources, service indicators, quality indicators, parts costs and contracts. Among the findings, the highlight was an approximately 20% reduction in corrective maintenance at the moment of implementation of preventive maintenance and the stabilizing of corrective despite the increase of the technological park of the institution over the 10 years studied. The preventive maintenance reached its highest rate in 2007 with 33% of all maintenance, having a 27% reduction in 2010. In the overall amount of spending on contracts, there was a reduction of about 2/3 in the study period. The savings generated by the Clinical Engineering management for the institution was approximately R$ 2million in 2010, and the cumulative savings over the period 2001 to 2010 was R$ 7.6million. It was concluded therefore that the management of clinical engineering in that institution, enabled a reduction in hospital costs and promote increased of the medical equipment availability and quality assurance and reliability of services provided.

The deregulation of the electricity sector and the evolution in the legislation related to the consumers right and economy growth - with the inclusion of more people in higher classes - have had a strong impact on the relationship between energy distribution companies and electricity consumers. The Strong management of Regulatory Agencies, with frequent application of penalties, has stimulated scientific research by the distribution companies and universities to identify the main causes of the conflicting aspects involving the consumer, the regulator and the energy concessionaire. In this context, a field of study that has generated growing importance is regarding the increase in requests for damage compensation to electronic equipment. If in a way the volume of requests and financial amount to cover these requests have rose highly on another way the lack of efficient mechanisms for analyzing the causal relationship between damage and motivator, has prevented consistent and conclusive analysis, multiplying the claims next to the ombudsman service. This work has as its main objectives: the construction of more real supportability curves from destructive tests and the proposed methodology; the inclusion of such curves in the new version of the APR software (developed in this study); the construction of a friendlier interface for importing data from the georeferenced system of the Energy Concessionaire for the mentioned software, in addition to conducting trials to test the effectiveness of mitigation devices known as DPS. Studies to guide the data were collected by the concessionaire CEMIG D, which guided the analysis for microcomputers, which have been used increasingly and also have had a larger volume / amount of money in requests for damages.

Optical Character Recognition systems (OCR) refer generically to technologies applied to recognize characters from an image file that contains text. It allows, for example, that a scanned sheet of printed text could be converted into an editable text file. These systems have been widespread over the past years, with several commercial versions, including the ones embedded within scanner devices. One of the steps that define the success or failure of this type of system is the correct segmentation of text lines and characters that constitute it. Recently, it has gained importance the correct segmentation of words in the textto assist possible post-processing steps to correct deviations of recognition. This paper presents two different methods for segmentation of texts. The first method, called Segmentation of Lines and Words based Teager energy operator (SLP-TEO), based on the Teager energy operator (TEO), is used in the segmentation of text lines and words. The TEO is applied to the signal abstracted from the linear projection (horizontal or vertical) generated by the binary image of the text. A unique feature of this method is that it can be applied to printed texts or manuscripts, without prior arrangements. Moreover, the same algorithm is used to segmentation of text lines and segmentation of words, no matter if they are printed or handwritten. The adopteddatabase for this project (IAM-Database), widely used in OCR researches, has, for all printed text, handwritten transcripts that were also targeted using SLP-TEO method. The second method, called gray-Region Oriented Segmentation of Characters (gROSC) is applied to grayscale word images for the purpose of character segmentation. This method is based on region oriented methodswhere connected pixels that are visited and labeled. A unique feature of the method is that it should be applied to grayscale images of the segmented words. Moreover, using the Otsu threshold and knowing the gray levels of the image in advance, the method determines the maximum variation between shades of gray that allows or not to visit the neighboring pixel, adding it to the target region of interest. In the adopted database, there are three basic types of characters problems to solve: overlapping characters, connected characters, and font design. The gROSCmethod is applied to all previously segmented words images, and the characters are equally segmented, without previous identification of possible character problems. The experiments and results in all stages of segmentation with both methods are very relevant and demonstrate the efficiency and simplicity of the proposed methods.

Aneel Ordinance No. 414 of September 9, 2010, guarantees the right to consumers of electricity supplied at a voltage equal to or less than 2.3 kV, in case of damage caused by disruption occurred in the system, replacement of damaged electrical equipment, installed in consumer units, operating in the same condition found prior to the occurrence or, alternatively, compensation in cash equivalent to that required to make it return to that condition, or even replaced with equivalent equipment, regardless of fault of the concessionaire. The consumer has up to 90 (ninety) days from the date of the likely occurrence of lightning damage to equipment, to request reimbursement to the distributor, and provide at least the following elements, according to the ordinance above: I - likely date and time the damage occurred; II - information showing that the applicant is the holder of the consumer unit, or his legal representative; III - report of the problem presented by electrical equipment, and IV - Description and general characteristics of the damaged equipment, such as brand and model. The same decree states that the distributor should investigate the existence of causation, even considering the records of occurrences in your network and must inform the consumer the result of the reimbursement request in writing within 15 (fifteen) days from the date of the check or, failing that, from the date of the request for reimbursement. Also in case of refusal, the distributor must provide the consumer with a standardized application form in writing, containing at least the detailed reasons for the rejection. Due to the complexity of the analysis of power system disturbances propagated by the concessionaire and the lack of tools to support such analysis, what we see today are simplistic analysis, often based on technical reports from an authorized dealer, which suggests a possible origin for the defect. The concessionaire will often choose to make the compensation to avoid wear and image conflicts with their customers. Thus, given the new demands of the current ordinance, the need to establish a scientific methodology and easy operation, the growing number of complaints and a high cost of claims paid, utilities have invested in research R & D from scientific institutions to obtain procedures that can contribute to a more transparent, fair and scientific basis for this scenario. That said, this dissertation has met the needs listed above, proposing a methodology for examining applications for reimbursements of televisions based on the new curves and dielectric withstand unprecedented thermal curves, integrating quickly and easily to the geo-referenced database the system\'s electrical utility Cemig SA, culminating in a software for easy operation.

In the past few years, computer-based training systems have been widely studied in the field of human rehabilitation. One of the cutting-edge technologies applied in this kind of system is Virtual Reality. In health applications, Virtual Reality presents itself as an appropriate tool to simulate training environments without exposing the patients to the real world associated risks. In particular, one application of Virtual Reality in human rehabilitation is in virtual prosthesis design. Virtual prosthetic devices have been used to reduce the great mental effort needed by patients fitted with myoelectric prosthesis, during the training stage. This effort is one of the main difficulties that lead patients to give up at this stage. In this paper, the application of Virtual Reality in a hand prosthesis training system is presented. To achieve this, the possibility of exploring Artificial Neural Networks in a real-time classification system is discussed. Also, a signal windowing algorithm and a communication architecture between the classification system and the virtual environment are presented. Finally, a prototype developed in order to investigate the application of the proposed system in a real-time processing and classification context is presented.