Simulation Tools of DC-DC Converters for Power Electronics Education

This paper presents interactive simulation tools to support the enhancement of power electronics education considering DC to DC converters. These interactive tools make use of the benefits of Java language to provide a dynamic and interactive visualization of simulations in steady-state for idealized non-isolated DC to DC converters. Additionally, this paper discusses the features and the usage of the interactive educational tools to serve as a first design tool for the laboratory experiments in the power electronics courses. In this way, some results were confronted with a well-known simulator package and with experimental results in order to validate the developed interactive simulation tools.

DC Electric Field Dependence of the Dielectric Constant of Pzt Thin Films Prepared by Polymeric Precursor Method

This work reports dielectric measurements performed on Pb(Zr0.53Ti0.47)O3 (PZT) thin films prepared by a polymeric precursor method. The -E curves obtained for the PZT film measured at 100 kHz, under a small ac 0.2 kV/cm signal-test and a dc scan featured a typical butterfly curve. However, the -E curves obtained for PZT film under a dc scan, with a scan rate of 0.003 V/s, shows a pronounced asymmetry. The absence of a symmetric secondary peak in -E curves could be an indication of essentially 180 domain switching.

Leaf emergences in Microlepis oleaefolia (DC.) Triana (Melastomataceae) and their probable function: An anatomical and ultrastructural study

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

Evaluation of the antiulcerogenic and analgesic activities of Cordia verbenacea DC. (Boraginaceae)

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

Effect of Baccharis dracunculifolia DC (Asteraeeae) extracts and its isolated compounds on macrophage activation

Baccharis dracunculifolia D.C. (Asteraceae), a shrub which grows wild in Brazil, is the main botanical source of Brazilian green propolis. Since Brazilian propolis shows an immunomodulatory activity, the goal of this work was to evaluate the action of B. dracunculifolia extracts and some of its isolated compounds on reactive oxygen intermediate (H2O2) production by macrophages obtained from male BALB/c mice. The results showed that the leaf (Bd-L) (25, 50, and 100 mu g mL(-1)), leaf rinse (Bd-LR) (25 mu g mL(-1)), and the root (Bd-R) (25 mu g mL(-1)) extracts enhanced H2O2 release by macrophages. A phytochemical study of the root and leaves of B. dracunculifolia was carried out. The chromatographic fractionation of Bd-R, using several techniques, afforded the isolation of baccharis oxide (1), friedelanol (2), viscidone (11), 11-hydroxy-10,11-dihydro-euparin (12), and 6-hydroxy-tremetona (13), while Bd-LR gave the following isolated compounds: baccharis oxide (1), friedelanol (2), isosakuranetin (3), aromadendrin-4'-methyl ether (4), dihydrocumaric acid (5), baccharin (6), hautriwaic acid lactone (7), hautriwaic acid acetate (8), drupanin (9), and cumaric acid (10). Among the isolated compounds, baccharis oxide (1) and friedelanol (2) increased H2O2 production at a concentration of 1001,M. This is the first time that the presence of compounds 7, 8, 12, and 13 in B. dracunculifolia has been reported. Based on these results it is suggested that the crude extracts and some isolated compounds from B. dracunculifolia display an immunomodulatory action.

Estudo morfo-anatômico de folhas de Jacaratia spinosa (Aubl.) A.DC. (Caricaceae)

Aspectos morfológicos e anatômicos da folha de Jacaratia spinosa (Aubl.) A.DC. (Caricaceae) foram estudados com detalhe. O limbo foliar possui organização dorsiventral, estômago anomocíticos, glândulas, laticíferos do tipo articulado anastomosado e epiderme papilosa na face abaxial. A venação é bronquidódroma terminando em alças no bordo foliar.

Sistema de reprodução de Rhynchanthera dichotoma (Lam.) DC

R. dichotoma (Lam.) DC. é um arbusto que ocorre na região central do Brasil em ambientes úmidos, brejosos, formando nestes locais grandes populações. O período de floração desta espécie é longo de 6-8 meses. Neste estudo realizado no município de Tanabi (São Paulo), o pico de floração ocorreu no mês de abril. Semelhante ao observado em outras Melastomataceae de anteras tubulares e deiscência poricida, R. dichotoma é polinizada por abelhas vibradoras. Este estudo constatou que esta espécie é autocompatível com 59% de sucesso obtido nas autopolinizações manuais (n=90) e não foi observada a presença de agamospernmia (n=85). A polinização cruzada (xenogamia) foi predominante, sendo que 66% das flores polinizadas desenvolveram frutos (n=92). Surpreendentemente, apesar desta espécie apresentar anteras poricidas constatou-se a ocorrência de autopolinização espontânea em 33% das flores (n=92).

A note on the attenuation of the sommerfeld effect of a non-ideal system taking into account a MR damper and the complete model of a DC motor

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Induced polarization, resistivity, and self-potential: a case history of contamination evaluation due to landfill leakage

This article compares the efficiency of induced polarization (IP) and resistivity in characterizing a contamination plume due to landfill leakage in a typical tropical environment. The resistivity survey revealed denser electrical current flow that induced lower resistivity values due to the high ionic content. The increased ionic concentration diminished the distance of the ionic charges close to the membrane, causing a decrease in the IP phenomena. In addition, the self-potential (SP) method was used to characterize the preferential flow direction of the area. The SP method proved to be effective at determining the flow direction; it is also fast and economical. In this study, the resistivity results were better correlated with the presence of contamination (lower resistivity) than the IP (lower chargeability) data.

Avaliação química e da atividade antidiarréica das folhas de Byrsonima cinera DC. (Malpighiaceae)

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

The epiphytic Cactaceae Hylocereus setaceus (Salm-Dick ex DC.) ralf bauer seed germination is controlled by light and temperature

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

Germination response of Hylocereus setaceus (Salm-Dyck ex DC: ) Ralf Bauer (Cactaceae) seeds to temperature and reduced water potentials

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