Examinando por Materia "Energy conversion"

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    Quadratic boost converter with low-output-voltage ripple
    (IET Power Electronics, 2020-06-17) López-Santos, Oswaldo; Mayo-Maldonado, Jonathan C.; Rosas-Caro, Julio C.; Valdez-Resendiz, Jesus E.; Zambrano-Prada, David A.; Ruiz-Martinez, Omar F.
    his study proposes a non-isolated quadratic boost converter (QBC) that features a low-output-voltage ripple with respect to traditional QBCs. This advantage is in contrast with other topologies that require a higher amount of stored energy by capacitors to achieve the same output-voltage ripple specification. This benefit permits to design a compact converter, since the size of capacitors is proportional to their energy storage rating. Moreover, the proposed transformerless topology is suitable for applications that require high-voltage gains as in the case of renewable energy applications. The main properties of the converter are corroborated as well as its advantages by providing mathematical models, analytical waveforms and experiments.
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    Thermal Transport Measurements of LaCoO3 and SrTiO3
    (Journal of Superconductivity and Novel Magnetism, 2018-08-16) Cortes, Alexander; Trujillo Hernández, Juan Sebastián; Piamba, Jefferson; Lopera, Wilson; Prieto, Pedro
    Thermal conductivity and thermopower measurements as functions of temperature were carried out on SrTiO3 single crystals below room temperature and compared to those obtained for LaCoO3 polycrystalline samples. The maximum value of thermal conductivity for SrTiO3 (110) and Nb-doped SrTiO3 single crystals was 1.09 and 0.91 W/mK, respectively, at 300 K. The thermopower measurements were − 5.47 and − 41.17 μ V/K, respectively, at 300 K. This indicates the predominance of negative charge carriers or electrons in the material. Measurements on LaCoO3 polycrystalline samples yielded maximum values of 0.37 W/mK and 620 μ V/K for thermal conductivity and thermopower, respectively. These positive values suggest that positive charge carriers are predominant or that the compound is slightly hole-doped. We studied the effect of Nb doping on the thermopower and thermal conductivity of SrTiO3 and contrasted the results obtained with similar measurements on LaCoO3.