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In this work, an alternative Experimental Didactic Kit for teaching resistors, capacitors and "RC" timing circuits was developed, using the Arduino platform technology, which is composed of a microcontroller and peripherals, due to the easy access to available teaching materials, enabling the reproduction of the prototype in the future by people with little knowledge in the area, and because it is an open-source platform. In addition, it allows visually impaired students to participate in the activity. The experimental results are in good agreement with the theoretical ones. Moreover, it can be used as a great option to study resistors and capacitors in general. It also allows for a more detailed work, presenting an advantage in the teaching-learning process when compared to the traditional method, awakening in the student the interest in the study of Physics. We believe that this material is very useful in physics classes, being a great option for other teachers, aiming to improve students' knowledge and skills.

Novel Eu2+,3+/Yb3+ co-doping calcium aluminosilicate glasses prepared under a vacuum atmosphere were developed and characterized from the spectroscopic point of view, as a potential spectral converter for application in solar cells. The emission of near-infrared photons by downconversion due to cooperative energy transfer (ET) from Eu2+ and Eu3+ to Yb3+ in these glasses was reported. Absorption, excitation, emission, and fluorescence decay measurements were performed to examine the ET processes. The occurrence of cooperative energy transfer from Eu2+ and/or Eu3+ to Yb3+ ions was discussed in detail. The obtained samples have high efficiency and broad absorption in the ultraviolet and visible regions. Under 325 nm excitation, the samples achieve intense near-infrared emission, which increases with Yb2O3 concentration (0 < Yb2O3 < 1.38 mol. %). The energy transfer efficiency from Eu2+,3+ to Yb3+ was evaluated, and a maximum efficiency of ∼85% was obtained (Yb2O3 = 1.38 mol. %). [ABSTRACT FROM AUTHOR]

Optical losses are the major drawback to overcome in the solar energy industry and development. Conversion of solar radiation into heat accounts for over 80% of the incident solar energy, which is driven by several aspects like the chosen design and encapsulation of the devices, built-in materials, and the mismatch between the solar spectrum and the active cell's bandgap energy. Photoacoustic (PA) and photothermal (PT) methods are characterization techniques based on the heat generation after the illumination of a material and respective detection. Since the beginning of the solar panel industrial development, these methods have been successfully applied to evaluate the photovoltaic efficiency of devices and the thermophysical parameters of related materials. Here, we present the state-of-art of application of these PA and PT methods to characterize solar cell devices and their built-in materials. Historical aspects, conceptual mechanisms of the basic phenomena, and perspectives on their application for energy-conversion measurements in the new frontier of solar cell research will be discussed. [ABSTRACT FROM AUTHOR]

Recent theory has predicted that spectral converters would be a promising pathway to improve the spectral response of silicon solar cells. As a consequence, new materials and methods of coupling these sensitizers in photovoltaic cells have been investigated. In this work, a UV pulsed laser deposition technique was used to grow thin films of Nd3+–Yb3+ co-doped low silica calcium aluminosilicate glass on silicon substrates, aiming for the development of hybrid solar cells with spectral converters. The role of both laser shots and substrate temperature was investigated, as well as the film's optical and structural properties. Our films present no crystalline order (amorphous) and present a surface with a roughness of the order of sub-nanometers. Significant flat regions between grains were observed by AFM analyses. Photoacoustic spectroscopy was successfully developed to determine the thicknesses of thin films in a range higher than the limit of the x-ray reflectivity technique (≥170 nm). From 1000 to 20 000 laser shots, the film thicknesses increased from 27 to 680 nm. The photoluminescence measurements demonstrated efficient energy transfer processes toward the Yb3+ 950–1200 nm emission, suggesting this material as a promising spectral converter for the development of hybrid solar cells. [ABSTRACT FROM AUTHOR]

Polarimetric radar data collected by AIRSAR and SIR-C over agricultural fields, forests, and olive groves of the Italian Montespertoli site are analyzed. The objective is to investigate the radar capability in discriminating among various vegetation species and its sensitivity to agricultural and arboreous biomass. Results indicate that a combined use of P (0.45 GHz) and L (1.2 GHz) bands allows one to discriminate between agricultural fields and other targets, while a combined use of L and C (5.3 GHz) bands allows us to discriminate within agricultural areas. To monitor biomass, P band gives the best results for forests and olive groves, L band appears to be good for crops with low plant density ([m.sup.-2]), while for crops with high plant density, both L and C bands are useful. The availability of crosspolarized data is important for both classification and biomass retrieval. Index Terms - Biomass, classification, polarimetry, radar, vegetation.