Papers by Keyword: Tetrapod

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Authors: Niyom Hongsith, Supab Choopun
Abstract: Platinum impregnated ZnO tetrapods were prepared and studied for the detection of ethanol vapor. ZnO tetrapods were synthesized by oxidation reaction technique by heating a mixer of zinc powder (99.99%) and hydrogen peroxide solution (30 wt.%) at 1,000oC in air. Platinum was impregnated by dropping hydrogen hexachloroplatinate (IV) hydrate,, solution with different concentration on ZnO tetrapods and then, heated at 350oC for 1 hr. The platinum impregnated ZnO tetrapods were characterized by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) for morphology and chemical composition, respectively. The particles were observed on the surface of ZnO tetrapods. The EDS spectrum suggested that the particles were platinum. Platinum impregnated ZnO tetrapods were tested ethanol sensing properties under ethanol concentration of 50-1,000 ppm. The ethanol sensing results indicated that the sensitivity of the sensors depended on the platinum impregnated concentration. Moreover, the sensors based on platinum impregnated ZnO tetrapods of 0.035 wt.% exhibited higher sensitivity compare to those of non-impregnation ZnO tetrapods.
Authors: Jean-Jacques Delaunay, I. Nagatomo, R. Uchino, Y.B. Li, M. Shuzo, I. Yamada
Abstract: Layers of ZnO micro-nano structures were deposited on quartz substrates and subsequently plasma treated in O2 and N2. It was found that exposure to O2 plasma enhanced gas response to ethanol vapor of the ZnO layers by a factor 8, while exposure to N2 plasma deteriorated the gas response. This enhancement of the gas response upon O2 plasma treatment was attributed to the formation of nanocrystallites of ZnO on the original ZnO micro-nano structures which form the gas sensing layers. The surface chemical state of the original sample was found to be not affected by the O2 plasma while it was modified by the N2 treatment.
Authors: Alexander Janushevskis, Anatolijs Melnikovs, Alexander Boyko
Abstract: In this work resource saving technique is used for shape optimization of 3D mechanical objects. According to statistical data, appearance of cracks in the areas of barrel support pads of tank wagons often causes damages to the barrels. The shape optimization of barrel support pads of a tank wagon is implemented and, as result, the concentration of stresses is significantly reduced in the barrel support areas. The optimization technique is based on CAD/CAE, design of experiment, approximation and optimization software packages. The shape of the support pads is defined by NURBS polygon points that serve as design parameters. For reduction of computational resources, FE models of tank wagon are replaced with high-quality metamodels which are based on locally weighted polynomials. The specific recommendations for the shape of the pads are given. As the second object truly spatial tetrapod is considered. The optimal curved shape of the tetrapod for lattice structure is elaborated.
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