RCAAP Repository

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

This paper presents a mathematical method that enables the achievement of the grounding resistance and the potential of the soil surface, generated by a grounding system, it consists of a buried cable horizontally. The grounding is present in the first layer of soil, assuming a soil composed of \"n\" horizontal layers. From this mathematical model a computer program developed to calculate the ground resistance and potential surface of the horizontal cable. For the validation of this mathematical model several experimental tests were performed, allowing the theoretical and experimental evidence. Simulations are also conducted to observe the influence of the layers in order ro determinate the grounding resistance and surface potentials, and also the influence on the accuracy of soil stratification into horizontal layers.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

The subject power quality contemplates diverse aspects relative to the conformity of the product electric energy, in special, the voltage. Amongst the subjects that are treated under such assignment, it is the question of the harmonic distortions, which in the present time have increased considerately in the most distinct constituent points of the electrical systems. Therefore, regulating agencies, concessionaires and consumers have shown an increasing concern on the reached levels for this pointer of the quality of the electric supply. For the harmful character of these riots, international and national norms and recommendations have looked for to establish limits for the distortions. These documents, in a general way, prime for the definition of values of reference for the pointers of the total and individual distortions, without, however, entering in the merit of the origin of the same ones. In these terms, a time evidenced a breaking of the established limits and defined the necessity of the implementation of a systematic of mitigating of the effect, appears the question of the financial responsibility associated to the process to be implemented. Inserted in this context, the subject is placed "sharing of responsibility", which consists of center of this work. Thus, this work meets directed to synthesize the state of the art on the subject, considering, above of everything, the main found proposals of sharing in literature, which is: Method of the Harmonic Power, Method of the Current Conforming and Non-conforming and Method of the Overlapping. To leave of these, using experimental and computational procedures, it is proceeded the evaluation and critical analysis from the suggested procedures, detaching its potentialities and limitations.

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

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

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

With the advent of new technologies, the TV had enhanced transmission processes, from analog signal to digital, bring great benefits to the viewers from the image quality, audio 5.1, interactivity, the presence of adjacent channels, multiple programming and mobile devices. All these benefits are possible due to better spectrum utilization and digital technology. However, television stations in Brazil will face many challenges in the implementation of digital system: will have to keep the scope of the analog signal with digital technology; keep signal quality at different points of the city; good signal reception indoors where there is no external antenna UHF, and mobile reception with high quality. Moreover, with the growth of the civil construction sector in Brazil has expanded the number of obstacles between the transmitter and receiver. Thus, there were other forms of interference in the spread as reflection, refraction and scattering, caused mainly by the terrain profile, buildings and other obstacles present on the route. Accordingly, the stations must make constant the signal propagation survey for possible shadow regions in the city, in order to implement signal repeaters in the region. Another analysis that can be done is to use spread software capable of plotting the spots of the UHF and VHF signal in order to choose the best propagation method to be adopted to reach a more realistic / accurate model. With the transition from analog to digital technology and the shutdown of the analog signal provided for 2018 in Uberlândia a study of the quality of the digital TV signal will be needed in this city, with measurements of the intensity of the digital signal in various city points and an analysis of the project technician with the measured value in the field. In this sense, this work aims to collect electric field data and electrical power digital terrestrial television signal in urban areas of Uberlândia, Minas Gerais, and thus make comparisons of the measured values with the theoretical of propagation models ITU-R P .1546, Okumura-Hata and Log-Distância of operating TV stations the digital signal in the city.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

The Intracranial hypertension (ICH) is a neurological condition that primarily affects patients with Traumatic Brain Injury (TBI), cerebrovascular accident (CVA) and hydrocephalus. Currently, the most suitable treatment of this condition requires continuous monitoring of brain clinical parameters associated with cerebral perfusion. In this context, two variables are highly relevant in clinical evaluations: intracranial pressure (ICP) and mean arterial pressure (MAP). There is a technological need, both nationally and internationally, of a system to obtain information from the PIC and the MAP in order to improve the monitoring of patients in neurological intensive care units. In this context, this research proposed the development of a computational tool able to provide relevant clinical parameters to monitor the evolution of patients. The software provides the correlation of PIC waveform with mean arterial pressure by setting the cerebral perfusion pressure more ideal for every patient assessed, using the Pearson correlation coefficient after scanning of said analog signals (PIC and PAM) to 0.06 Hz (low-PRx). The system interface displays the following parameters: ICP, MAP, cerebral perfusion pressure (CPP), cerebral vasoreactivity index (PRx) and further assesses the decomposition of PRx using the decomposition method of empirical oscillations (English, Empirical Mode Decomposition). To illustrate the application of the tool developed was conducted a case study concerning a five patients sampling monitored in the ICU of a referral hospital. The use of the developed tool enabled the evaluation of the most appropriate PPC for each patient assessed, and the results compared with those provided by Glasgow Prognostic Scale (English, GOS - Glasgow Outcome Scale). The developed tool is useful in evaluating the ICP, CPP and PRx in patients monitored in the neurological ICU.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The present work has as the main goal to introduce a new method to select the sample time of input and output signals used in the identification process using NARMAX representation. To achieve this goal is proposed a genetic algorithm wich uses a supersampled signal, i.e., a signal sampled in the most high frequency available, and later decimation rates are used to create different individuals from the high frequency sample signal. The individuals evaluation uses a system identification with NARMAX representation. The evaluation of the proposed method used a genetic algorithm developed in the software Matlab®. The proposed method was applied in the process identification of a polimeric membrane fuel cell temperature model and the results are presented.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The objective of this work is to develop real time dynamic simulators to use them as supporting tools in instrumentation and process control technical courses. The developed simulators are as following : - simulator for the equipment to test control valves showing all the acessories necessary to test a control valve. In this phase the concepts of Cv, curves inherent and installed of a control valve are introduced. - simulator in real time of a level control using P+I+D controller for a tank with the form of cylinder in the vertical position, in this phase the Ziegler-Nichols tunning methods are presented for systems with different response times and which are the influence of the control valve gain in the calculated tunning parameters. In this phase a system with fast response are presented. The same simulation is made using the same system with larger response time. During this simulation the influence of the gain of the valve is shown in the process response of the control and what is procedure to solve this problem. At this part, the advantages and disadvantages of the Ziegler-Nichols tunning methods in a practical applications. - simulator in real time of three elements level control for a boiler. In this phase a experimental method is showing for controller's tunning parameters. The experimental method presents advantages of practical order in reference of Ziegler- Nichols method. - This work was developed to permits to analyse the behaviour of dynamic system as well to study solutions that can do in the classroom without the concerns about safety which normally occurs in the industrial environment. The great target of this work is to show in the classroom experimental methods, as the own name indicates, only can be done in the real equipment. Also we believe that sigficant coast reduction can be achieve if simulators are used instead pilots plants.

This dissertation presents an educational software which explores Virtual Reality techniques (VR) through the development of virtual educational environments. 3D Geometry has been taken as a case study. The objective of this work is the extension of the cut for convex and non-convex polyhedron. The virtual environment and the interaction techniques have been developed using the VRML (Virtual Reality Modeling Language) and JavaScript languages. After making the system available to potential users, they were able to do some experiments and confirmed that the techniques proposed are satisfactory and helpful in the learning process and in the visualization of non-convex polyhedron.

When the suply chain of medicine logistic is analysed, critical points can be found in the actual model of deliveries to the drugstores, which are the direct clients of the dealer. The clients demand full requests to be delivered on time. In this context, this work starts with the evaluation of the logistic process of the dealer. A field study has been conducted in order to diagnose and develop a core system for vehicle routing. The idea is that an optimized delivering process will reduce costs and, most importantly, the delay on deliveries. Considering the complexity and relevance of the problem in the context of logistics, the chosen approach uses genetic algorithms as the metaheuristic. It is robust enough to tackle the given problem. It is an interactive method with some intelligence in the process of searching for solutions which does not stop on the first local optimum that is found. The problem is to optimize the allocation of deliveries to the available vehicles, taking into account the restrictions of each vehicle, in such a way that the total travelled distance will be minimized. The representation of the solutions and the genetic operators used are based on the travelling salesman problem. In order to produce competitive results on this class of problems, Genetic Algorithms need to be associated with a local method of search. This should be done at each iteration of the algorithm. This allows the generation of better solutions when compared to conventional heuristic methods. The system has been implemented in the Ocaml programming language. Ocaml is a modern language which allow quick development and the code is less error prone, when compared to other programming languages common on the software market, like C, C++ and Java. Known problems from the literature have been used to test the system. The results show that it is possible to obtain optimized routers to solve the problem of delivery of medicines to the clients, taking into account restrictions like capacity of vehicles and transported value limitations.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior