Isotopic separation of silicon atoms by atomic mirror

The isotopic separation of silicon by an atomic mirror has been demonstrated numerically, by which each silicon isotope encounters a different dipole force depending on the frequency detuning due to the different frequencies resonant to the silicon isotopes. It was found that the atomic mirror, which comprised a wave guide structure designed for the enhancement of evanescent waves at 252 nm, allows us to discriminate ²⁹Si from the other isotopes.     

Three-scale analysis of BaTiO<Subscript>3</Subscript> piezoelectric thin films fabrication process and its experimental validation

A three-scale analysis of crystal growth process is newly proposed based on the first-principles calculation and on the finite element analysis in order to generate a new biocompatible piezoelectric thin film. Crystal growth process of lead-free BaTiO₃ thin films was designed and experimentally generated on SrTiO₃(100), (110), (111), and MgO(100) substrates using the radio-frequency magnetron sputtering method. Crystal structures of BaTiO₃ were measured by X-ray diffraction (XRD) θ/2θ scan. We used Pt for the electrode and measured piezoelectric strain constants d ₃₃ using the ferroelectric measurement system. As a result, analytical crystal orientation fractions on SrTiO₃(110) and (111) substrates had good quantitative agreement with experimental ones, and ones on SrTiO₃(100) and MgO(100) substrates corresponded with these experimental crystal structures. Furthermore, analytically determined piezoelectric strain constants d ₃₃ qualitatively showed a good agreement with experimental ones. Especially, for SrTiO₃(100) and MgO(100) substrates, the differences of d ₃₃ depending on orientation fractions were analyzed by the three-scale simulation accurately. Consequently, it is confirmed that the three-scale analysis is a useful simulation tool to design new biocompatible piezoelectric thin films.     

Estimating the imageability of words by mining visual characteristics from crawled image data

Multimedia Tools and Applications - Natural Language Processing and multi-modal analyses are key elements in many applications. However, the semantic gap is an everlasting problem, leading to...     

Two-step homogenization simulation for multidomain and multigrain structures in piezoelectric materials

In this paper, a two-step scale-up procedure based on asymptotic homogenization theory is proposed for hierarchical structures consisting of multigrains and multidomains in piezoelectric materials. Intragranular domains are modeled as a microstructure during the first-step homogenization. Then, in the second-step homogenization, an aggregate of randomly oriented grains is modeled by applying the first-step homogenized material properties of multidomains to every grain. A dual-domain structure consisting of positive and negative directional domains with a 180° orientation gap is computed for case study analysis. The three-dimensional electron backscatter diffraction-measured microstructure is employed for the multigrain structure. The effect of the domain configuration on the macroscopic homogenized material properties of polycrystalline piezoelectric materials is investigated through the two-step homogenization process. In particular, the material property changes caused by the piezoelectric effect, which cannot be estimated by the mixture law, are discussed for multigrain and multidomain structures.     

Development of HVAC system simulation tool for life cycle energy management Part 1: Concept of life cycle energy management and outline of the developed simulation tool

The importance of LCEM (life cycle energy management) has been recognized from the view of life cycle energy savings for sustainable buildings. The purposes of this research are the proposal of an LCEM framework and development of prototype HVAC system simulation tools for LCEM. In this paper, the necessity of energy simulation tools for LCEM is discussed, and the outline and solution method of the simulation tool are shown.     

Minority carrier controlled PEC solar cells, using n-Si electrodes modified with LB layers of ultrafine Pt particles

The open-circuit photovoltages (V_OC^S) of photoelectrochemical (PEC) solar cells, equipped with n-Si electrodes modified with ultrafine platinum (Pt) particles, have been investigated as functions of the Pt-particle density and the post-heat-treatment temperature. Langmuir-Blodgett layers of Pt-colloid particles stabilized by polyvinylpyrrolidone (PVP) are used to control the Pt-particle density on the n-Si electrodes. The ideality factor (n) and the dark saturation current density (j₀) are determined from plots of logarithm of the short-circuit photocurrent density versus V_OC. The n is unity for all the electrodes, independent of both the Pt density and the heat-treatment temperature, indicating that an ideal n-Si/solution junction is formed. The j₀ decreases and, hence, the V_OC increases as the Pt density decreases and also as the post-heat-treatment temperature is decreased. The decrease of j₀ is caused by the decrease in the majority carrier dark current density (j_0n). In cases where the Pt-modified n-Si electrodes are heat-treated at a low temperature of 150°C or not heat-treated, V_OC is in the range of 0.61 to 0.63 V, independent of the Pt density, indicating that minority carrier controlled solar cells are obtained.     

Effect of lightning overvoltages on low-voltage power distribution lines due to direct lightning hits to overhead ground wire

Overhead ground wires and surge arresters have been installed to protect high-voltage power distribution lines and apparatus from overvoltages induced by nearby lightning strokes. The effects of surge arresters for protection of high-voltage distribution lines against direct lightning strokes have already been investigated using the digital simulation program EMTP (Electromagnetic Transients Program). With regard to the protection of low-voltage distribution lines from overvoltages induced by lightning strokes, experimental analyses using a scale model line have been reported. This paper reports on the comparison between the experimental analyses and EMTP simulation of power distribution lines, including low-voltage lines, and the validity of EMTP simulation. Furthermore, this paper analyzes the overvoltages on low-voltage power distribution lines against direct lightning strokes to overhead ground wire using the digital simulation.     

Mesoporous materials from leached calcium silicates with hollow structure

Mesoporous materials with hollow structures were obtained from leached calcium silicate as silica source. The material with wormhole pores was synthesized using hexadecyltrimethylammonium chloride as a surfactant in basic condition. The material with three-dimensional (3D) cage pores like MCM-48 was obtained using hexadecyltrimethylammonium bromide in basic condition with ethanol as an additive. Both materials have not only regular mesopores but also macropores due to their hollow morphologies. The succession of local dissolution and deposition, with an insoluble part playing as a substrate for precipitation, produced the mesoporous materials which resemble the morphology of the silica source.