Modeling of piezoelectric energy harvesting considering the dependence of the rectifier circuit

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Uma investigação do minos e sua aplicação ao problema de fluxo de potência ótimo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A Modified Branch and Bound Algorithm to Solve the Transmission Expansion Planning Problem

In this paper a novel Branch and Bound (B&B) algorithm to solve the transmission expansion planning which is a non-convex mixed integer nonlinear programming problem (MINLP) is presented. Based on defining the options of the separating variables and makes a search in breadth, we call this algorithm a B&BML algorithm. The proposed algorithm is implemented in AMPL and an open source Ipopt solver is used to solve the nonlinear programming (NLP) problems of all candidates in the B&B tree. Strategies have been developed to address the problem of non-linearity and non-convexity of the search region. The proposed algorithm is applied to the problem of long-term transmission expansion planning modeled as an MINLP problem. The proposed algorithm has carried out on five commonly used test systems such as Garver 6-Bus, IEEE 24-Bus, 46-Bus South Brazilian test systems, Bolivian 57-Bus, and Colombian 93-Bus. Results show that the proposed methodology not only can find the best known solution but it also yields a large reduction between 24% to 77.6% in the number of NLP problems regarding to the size of the systems.

Estudo das propriedades dinâmicas e sincronização no mapa de rede de Zaslavsky

Synchronization in nonlinear dynamical systems, especially in chaotic systems, is field of research in several areas of knowledge, such as Mechanical Engineering and Electrical Engineering, Biology, Physics, among others. In simple terms, two systems are synchronized if after a certain time, they have similar behavior or occurring at the same time. The sound and image in a film is an example of this phenomenon in our daily lives. The studies of synchronization include studies of continuous dynamic systems, governed by differential equations or studies of discrete time dynamical systems, also called maps. Maps correspond, in general, discretizations of differential equations and are widely used to model physical systems, mainly due to its ease of computational. It is enough to make iterations from given initial conditions for knowing the trajectories of system. This completion of course work based on the study of the map called ”Zaslavksy Web Map”. The Zaslavksy Web Map is a result of the combination of the movements of a particle in a constant magnetic field and a wave electrostatic propagating perpendicular to the magnetic field. Apart from interest in the particularities of this map, there was objective the deepening of concepts of nonlinear dynamics, as equilibrium points, linear stability, stability non-linear, bifurcation and chaos

Uma discussão sobre o ensino da estatística para os estudantes de graduação na França, no Brasil, e nos Estados Unidos

Today statistics are one of the most important bases of the engineer formation. Statistics are used indirectly every day for engineers in a large panel of sectors like construction, mechanical engineering, biological engineering, electrical engineering, computer science etc. The main goal of this report is to compare different ways the engineers of tomorrow are formed in order to show which engineering is the best practice. The comparison will be done on different universities in France, Brazil and the US on Mechanical, Civil, Electrical and Production branches. We will compare the amount of courses required, the degree of knowledge needed and the mains subjects

Planejamento e organização das atividades de manutenção em instalações elétricas prediais e seus componentes

Are presented on this paper, concepts of corrective, preventive and predictive maintenances, following the prerequisites for planning and implementation of a maintenance plan. You also find the theoretical introduction of some measurement instruments accompanied by the necessary and recommended activities during routine maintenances of the electrical equipments in a building installation. Using case study, it is possible to assess a real maintenance plan applied to two occupied floors in a financial institution. The developing of a case study consolidates the effectiveness of the present concepts on this theoretical introduction and shows that the current maintenance plan can be improved in order to obtain better results on company productivity and reliability of equipments. As a conclusion, we can notice the importance of a solid maintenance plan and the need of including this theme on the graduation in Electrical Engineering

Sistema de Acelerador Linear Comercial para Radioterapia

This paper presents a study about the operation of the major system’s components of a linear particle acclerator (Linac). It addresses the components mainly responsible for the formation of the beam, through the inclusion of several block diagrams showing the details of the structure. Among the systems discussed may be mentioned the system modulator, automatic frequency control, dosimetry and auxiliary systems. The main objective is the dissemination of basic technology applied in linear accelerators and create literature about this subject in national language. Despite the high complexity and large number of devices that comprise a linear accelerator, it has been developed an easy to understand text that adresses the most relevant issues to the operation of the linear accelerator from the point of view of electrical engineering

Discussão do projeto pedagógico de um curso avaliado no provão com conceito 'A' por cinco vezes consecutivas

This paper presents the drafting process of a pedagogical project developed and implemented in the Electrical Engineering Course at Faculty of Engineering, Campus Guaratinguetá UNESP. Applying the project in this course resulted in "A" concept classification in the old National Examination Course, known as MEC General Test (Provão), for five consecutive times. The text presents pre-existing scenario which culminated with the preparation of this new project, the points that guided its construction, the deployment strategy adopted, changing paradigms implemented and results obtained. The text also emphasizes the reasons which led it to be adopted as a starting point for the development of educational projects which resulted in the deployment of two new courses: Electrical Engineering from the Universidade Estadual de Londrina – UEL, and Engineering course control and Automation of Experimental Campus Sorocaba – UNESP.

Funções penalidade para o tratamento das variáveis discretas do problema de fluxo de potência ótimo reativo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aprimoramento de um baropodômetro eletrônico e análise de estabiliometria em voluntários com escoliose

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Aprimoramento de um baropodômetro eletrônico e análise de estabiliometria em voluntários com escoliose

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

SMAC multi-hop mesh routing protocol using IEEE 802.15.4

This paper discusses some aspects related to Wireless Sensor Networks over the IEEE 802.15.4 standard, and proposes, for the very first time, a mesh network topology with geographic routing integrated to the open Freescale protocol (SMAC - Simple Medium Access Control). For this is proposed the SMAC routing protocol. Before this work the SMAC protocol was suitable to perform one hop communications only. However, with the developed mechanisms, it is possible to use multi-hop communication. Performance results from the implemented protocol are presented and analyzed in order to define important requirements for wireless sensor networks, such as robustness, self-healing property and low latency. (c) 2011 Elsevier Ltd. All rights reserved.

Development and characterization of a distributed measurement system for the evaluation of voltage quality in electric power networks

The research activity carried out during the PhD course in Electrical Engineering belongs to the branch of electric and electronic measurements. The main subject of the present thesis is a distributed measurement system to be installed in Medium Voltage power networks, as well as the method developed to analyze data acquired by the measurement system itself and to monitor power quality. In chapter 2 the increasing interest towards power quality in electrical systems is illustrated, by reporting the international research activity inherent to the problem and the relevant standards and guidelines emitted. The aspect of the quality of voltage provided by utilities and influenced by customers in the various points of a network came out only in recent years, in particular as a consequence of the energy market liberalization. Usually, the concept of quality of the delivered energy has been associated mostly to its continuity. Hence the reliability was the main characteristic to be ensured for power systems. Nowadays, the number and duration of interruptions are the “quality indicators” commonly perceived by most customers; for this reason, a short section is dedicated also to network reliability and its regulation. In this contest it should be noted that although the measurement system developed during the research activity belongs to the field of power quality evaluation systems, the information registered in real time by its remote stations can be used to improve the system reliability too. Given the vast scenario of power quality degrading phenomena that usually can occur in distribution networks, the study has been focused on electromagnetic transients affecting line voltages. The outcome of such a study has been the design and realization of a distributed measurement system which continuously monitor the phase signals in different points of a network, detect the occurrence of transients superposed to the fundamental steady state component and register the time of occurrence of such events. The data set is finally used to locate the source of the transient disturbance propagating along the network lines. Most of the oscillatory transients affecting line voltages are due to faults occurring in any point of the distribution system and have to be seen before protection equipment intervention. An important conclusion is that the method can improve the monitored network reliability, since the knowledge of the location of a fault allows the energy manager to reduce as much as possible both the area of the network to be disconnected for protection purposes and the time spent by technical staff to recover the abnormal condition and/or the damage. The part of the thesis presenting the results of such a study and activity is structured as follows: chapter 3 deals with the propagation of electromagnetic transients in power systems by defining characteristics and causes of the phenomena and briefly reporting the theory and approaches used to study transients propagation. Then the state of the art concerning methods to detect and locate faults in distribution networks is presented. Finally the attention is paid on the particular technique adopted for the same purpose during the thesis, and the methods developed on the basis of such approach. Chapter 4 reports the configuration of the distribution networks on which the fault location method has been applied by means of simulations as well as the results obtained case by case. In this way the performance featured by the location procedure firstly in ideal then in realistic operating conditions are tested. In chapter 5 the measurement system designed to implement the transients detection and fault location method is presented. The hardware belonging to the measurement chain of every acquisition channel in remote stations is described. Then, the global measurement system is characterized by considering the non ideal aspects of each device that can concur to the final combined uncertainty on the estimated position of the fault in the network under test. Finally, such parameter is computed according to the Guide to the Expression of Uncertainty in Measurements, by means of a numeric procedure. In the last chapter a device is described that has been designed and realized during the PhD activity aiming at substituting the commercial capacitive voltage divider belonging to the conditioning block of the measurement chain. Such a study has been carried out aiming at providing an alternative to the used transducer that could feature equivalent performance and lower cost. In this way, the economical impact of the investment associated to the whole measurement system would be significantly reduced, making the method application much more feasible.

An adaptive solar radiation numerical model

[EN]A numerical model for the evaluation of solar radiation in different locations is presented. The solar radiation model is implemented taking into account the terrain surface using two-dimensional adaptive meshes of triangles that are constructed using a refinement/derefinement procedure in accordance with the variations of terrain surface and albedo. The selected methodology defines the terrain characteristics with a minimum number of points so that the computational cost is reduced for a given accuracy. The model can be used in atmospheric sciences as well as in other fields such as electrical engineering, since it allows the user to find the optimal location for maximum power generation in photovoltaic or solar thermal power plants...

Duality in complex stochastic boolean systems

[EN]Many different complex systems depend on a large number n of mutually independent random Boolean variables. The most useful representation for these systems –usually called complex stochastic Boolean systems (CSBSs)– is the intrinsic order graph. This is a directed graph on 2n vertices, corresponding to the 2n binary n-tuples (u1, . . . , un) ∈ {0, 1} n of 0s and 1s. In this paper, different duality properties of the intrinsic order graph are rigorously analyzed in detail. The results can be applied to many CSBSs arising from any scientific, technical or social area…