Proposal of a hybrid rectifier structure with HPF and low THD suitable for front-end trolleybuses systems supplied by AC distribution networks

This paper presents the development and the experimental analysis of a new single-phase hybrid rectifier structure with high power factor (PF) and low harmonic distortion of current (THDI), suitable for application in traction systems of electrical vehicles pulled by electrical motors (trolleybus), which are powered by urban distribution network. This front-end rectifier structure is capable of providing significant improvements in trolleybuses systems and in the urban distribution network costs, and efficiency. 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 power factor (HPF) and low THDI, as well as ordinary front-end converter. However, the power rating of the switched converter is about 34% of the total output power, assuring robustness and reliability. Therefore, the proposed structure was named single-phase HPF hybrid rectifier. A prototype rated at 15kW was developed and analyzed in laboratory. It was found that the input line current harmonic spectrum is in accordance with the harmonic limits imposed by IEC61000-3-4. The principle of operation, the mathematical analysis, the PWM control strategy, and experimental results are also presented in this paper. © 2009 IEEE.

Ensino e aprendizagem de estatística por meio da modelagem matemática: uma investigação com o ensino médio

Pós-graduação em Educação Matemática - IGCE

Formação continuada de professores em uma perspectiva da interação formador-formando

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

THE MAPPING IN THE CONTINUING EDUCATION OF TEACHERS: AN EXPERIENCE THROUGH DISTANCE LEARNING

In this work, we show the experience of continuing teacher education in Cartography in the period from 03/11/2009 to 03/11/2010, it was held by the Center for Continuing Education in Mathematics Education, Science and Environment (CECEMCA) - UNESP - Rio Claro, in DL (Distance Learning). This experience was through the extension course set in TelEduc platform. The course was titled Introduction to Cartography and aimed primarily: Present concepts of systematic and thematic mapping and its potential application in teaching practices, increase knowledge in the areas of Geography, Cartography and Environment; Offer alternatives for implementing content mapping in the classroom.

Before dividing we have to add: inter-viewing the foregrounds of indigenous students

Students' cultural diversity is an important factor to consider in a mathematics education concerned with equity. We argue that the significance of mathematics education is not only given by the understanding of mathematical concepts but also by students' foreground, that is, the students' perception of their future possibilities in life as made apparent to the individual by his/her social-political context. For students in a cultural borderline position, different reasons and intentions for engaging in mathematics learning may be related to the construction of meaning in mathematics. Through inter-viewing Brazilian Indian students' foreground, we illuminate the different types of significance given to mathematics education in their particular situation.

Higher education in evening courses in Brazil: history, growth and public policies at the beginning of the XXI Century

There are three distinct and complementary objectives in this article in order to clarify the higher education outline in Brazil, specifically evening courses (classes are held on weekdays, generally from 7:00 pm to 10:30 pm) and thesecurrent sector policies. The first objective is to present a short historical overview on the establishment of evening courses in Brazil, including those in the higher education level, occurred on the middle of last century. The second objective is to demonstrate the growth of evening higher education in Brazil, considering that in 1998, of the 2.1 million college enrollments, 55.3% were enrolled in evening courses; in 2010, twelve years later, of the 5.4 million students enrolled, there were 63.5% enrolled in evening courses. This expansion is due to the growing need of many students who must work while attending college, to defray costs of the study as well as personal and family costs. The reality of the working student is hostile considering external factors, such as transport problems, public security and lack of legislation for flexible working hours. The third objective is to discuss current public policies to expand eveningopenings in public institutions which represent nowadays only 16.1% of the 3.4 million enrollments for evening classes, including federal (6.8%), state (7.0%) and municipal (2.3%) institutions. In the third objective it is included the discussion of programs for scholarships and tuition loans. The methodology applied was to rescue historical information on the establishment and the expansion of evening courses in Brazil, analyzing the current general Brazilian policies and the specific ones from the State of São Paulo. The research results pointed to the importance of federal programs for scholarships and tuition loans for students from private institutions such as the 1,382,484 scholarships since 2004 (PROUNI Program) and the 847,000 tuition loans since 1999 (FIES Program). Important steps have been made by the Brazilian government. Considering that there are 3,987,424 enrollments in private institutions, the effectiveness of the programs for scholarships and tuition loans is still insufficient to meet the universal benefits for the student’s needs. Evening courses became the real instrument of social inclusion for many Brazilian youths and must be expanded quantitatively and qualitatively, with aggressive public policies, including also, scholarships and tuition loans.

Different bacterial models for in vitro induction of non-cavitated enamel caries-like lesions: microhardness and polarized light miscroscopy analyses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A competência leitora e suas relações com processos de ensino e aprendizagem da matemática

Pós-graduação em Docência para a Educação Básica - FC

Representações sociais de professores sobre inclusão e o projeto político pedagógico: a escola em movimento

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)