Dependence of the I–V characteristics of amorphous silicon solar cells on illumination intensity and temperature

Current-voltage characteristics of amorphous silicon (a-Si) solar cells are systematically investigated as functions of the illumination intensity and ambient temperature. The principle of superposition of the short-circuit current and the dark current, which is usually assumed for crystalline silicon solar cells, is not applicable to a-Si solar cells. It is shown, that the output current of a-Si solar cells at a given illumination intensity E₂mW/cm²I_E2(V) is expressed by a relatively simple equation, I_E2(V) = I_d(V) + (_{E2/100) × (I100(V) — Id(V))}, when the series resistance of the solar cells is negligible. Here, I_d(V) is the dark current, I₁₀₀(V) is the output current at an illumination of 100 mW/cm², and V is the applied voltage. Empirical formula to describe the dependence of the current-voltage characteristics on the illumination intensity and the temperature are presented and discussed.     

Effects of crystal orientation on bendability of aluminum alloy sheet

We investigated the effects of crystal orientation on the bendability of aluminum alloy sheets by experiments using single crystal specimens and finite element analysis using a crystal plasticity model. In the experimental investigation, single crystal specimens having cube and Goss orientations were made from a coarse-grained Al-Mg-Si alloy sheet. The cube single crystal specimens have shown an excellent bendability regardless of the bending direction. Meanwhile, the bendability of the Goss single crystal specimens strongly depended on the bending direction. The finite element analysis results are remarkably consistent with the experimental results.     

Anisotropic carbon nanotube papers fabricated from multiwalled carbon nanotube webs

We fabricated large-scale anisotropic carbon nanotube (CNT) paper sheets by stacking long-lasting multiwalled CNT (MWCNT) webs without using binder materials. The MWCNTs are highly aligned in the webs and they retain their alignment in the fabricated paper. Although MWCNTs are just connected by van der Waals force, tensile strength is as strong as 75.6 MPa. In addition, resistivity and thermal conductivity is as good as 2.5 × 10⁻³ Ω cm and 70 W/m K, respectively. The present high anisotropy ratios of 7.3 in resistivity and of 8.1 in thermal conductivity are due to the high alignment of the ultra-long MWCNTs which have lengths of millimeters. High-speed web drawing with a draw speed of over 10 m/s enables very rapid fabrication. The material properties of CNT structures can be measured by conventional methods for macroscopic samples rather than methods designed for nanomaterials. CNT web technology will enable CNTs to be used in new applications.     

Long-lived neutron-induced radioisotopes in OKTAVIAN facility concrete wall after 38 year-operation

An intense 14 MeV neutron source facility named OKTAVIAN was installed in the A15 building,Osaka University in 1981.Along the operation period,new radioisotopes with various half-life have been produced as neutron activation products in its concrete wall shield.In this work,we investigated the concrete wall in the heavy irradiation room of OKTAVIAN using gamma spectrometry method to discover the presence of radioisotope having large half-life value(long-lived radioisotope) as neutron activation ...     

Shape optimization of steady‐state heat‐conduction fields considering temperature dependency of thermal conductivity coefficient

This paper presents a numerical analysis method for shape optimization of domains with steady‐state heat‐conduction fields considering the temperature dependence of the thermal conductivity coefficient. In this paper, we formulate two shape optimization problems, namely, maximization of thermal dissipation on heat transfer boundaries and minimization of heat‐conduction fields. The shape gradient functions for these shape optimization problems are derived theoretically using the Lagrange multiplier method and formulae of the material derivative. Reshaping is accomplished using the traction method proposed as a solution to the shape optimization problems. The proposed method is validated from the results of two‐dimensional numerical analysis. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20374     

Introducing/reproducing of welding distortion and residual stress in analysis for elastic-plastic behaviors of steel plates under compressive loads

A series of analyses was carried out to elucidate treatment of welding imperfection for simulating elastic-plastic behaviors of steel plates under compressive loads. A thermal elastic-plastic analysis based on infinitesimal deformation theory was carried out on a single-pass butt-welding of thin steel plates to predict welding distortion and welding residual stress. The obtained welding distortion and welding residual stress were introduced into an elastic-plastic large deformation analysis as initial imperfection. However, it was elucidated that welding distortion and welding residual stress could not be reproduced precisely due to unbalanced force caused by the difference between both analysis theories. Therefore, it should be confirmed whether the introduced welding distortion and welding residual stress were reproduced with high accuracy. Consequently, if welding distortion and welding residual stress cannot be reproduced, the treatment such as the convergence calculation method applied in this study should be done for precise elucidation of the elastic-plastic behavior of plates under compressive loads.     

Present status of development of high chromium steel for Japanese FBR components

This paper presents the establishment of the provisional specifications and material strength standard of the high chromium (Cr) steels for fast breeder reactor (FBR) components. For the improvement of toughness and ductility of the steels, a series of mechanical tests and metallurgical examinations are performed for several kinds of high Cr steels with the controlled balance of tungsten (W) and molybdenum (Mo). In addition, the effect of heat treatment condition on material properties is also investigated. Based on these results, it is revealed that W should be diminished to achieve better ductility and toughness and that it is difficult to improve the long-term properties by changing heat treatment condition. Then the provisional specifications of the high Cr steel for FBR components are given and the provisional material strength standard is proposed for the specifications of the steel. The standard obtained in this study is utilized for the FBR plant design.     

Possible molecular mechanism of loss of homologous and heterologous gap junctional intercellular communication in rat liver epithelial cell lines

We have identified beta-galactosidase activity in purified bovine rod outer segments (ROS), using rho-nitrophenyl-beta-D-galactopyranoside (PNPG) and chlorophenol red-beta-D-galactopyranoside (CPRG) as substrates. This glycosylhydrolase activity did not appear to represent contamination from other retinal subcellular fractions, based upon the relative specific activities of beta-galactosidase vs. other hydrolases (N-acetyl-beta-glucosaminidase, alpha- and beta-mannosidase, alpha-fucosidase, and acid phosphatase) in bovine retina and ROS homogenates. Using PNPG as a substrate, two pH optima were observed (at 3.5 and 5.5), while the hydrolysis of CPRG exhibited a single, broad pH optimum centered at 5.5. In contrast, hydrolysis of PNPG and CPRG by retinal homogenates exhibited single pH optima, at 3.5 and 5.5., respectively. ROS beta-galactosidase activity increased linearly with time, temperature, and protein concentration, and obeyed Michaelis-Menten kinetics with both substrates. For PNPG, Vmax approximately 88 nmol/h/mg protein and the apparent Km approximately 147 microM. For CPRG, Vmax approximately 33 nmol/h/mg protein and the apparent Km approximately 50 microM. ROS beta-galactosidase activity was affected by carbohydrates and their derivatives: glucose, fucose, sucrose, maltose and N-acetyl-galactosamine were found to stimulate the activity, while D-galactono-gamma-lactone and, to a lesser extent, D-galactose were inhibitory. The enzyme activity also was slightly stimulated by [Cl-] and markedly by dithiothreitol (DTT), while rho-chloro-mercuribenzoic acid (PCMB) and rho-hydroxymercuribenzoic acid (PHMB) inactivated the enzyme. In addition, the enzymatic activity was also found to be differentially sensitive to various anionic and nonionic detergents. However, n-octyl-beta-D-glucoside was slightly stimulatory.(ABSTRACT TRUNCATED AT 250 WORDS)