Acquisition of optimal attribute subset through genetic algorithm using GNP‐based class association rule mining

Attribute selection is a technique to prune less relevant information and discover high‐quality knowledge. It is especially useful for the classification of a large database, because the preprocessing of data increases the possibility that predictor attributes given to the mining algorithm become more relevant to the class attribute. In this paper, a method to acquire the optimal attribute subset for the genetic network programming (GNP) based class association rule mining has been proposed, and this attribute selection process using genetic algorithm (GA) leads to a higher accuracy for classification. Class association rule mining through GNP is conducted with a small subset of data rather than the original large number of attributes; thus simple but important rules are obtained for classification while the local optimal problem is avoided. Simulation results with educational data show that the classification accuracy is largely improved from 52.73 to 74.54%, when classification is made using the optimal attribute subset. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Syntheses of alpha-arbutin-alpha-glycosides and their inhibitory effects on human tyrosinase

Alpha-arbutin is a tyrosinase inhibitor. We synthesized alpha-arbutin-alpha-glycosides by the transglycosylation reaction of cyclomaltodextrin glucanotransferase from Bacillus macerans using alpha-arbutin and starch as acceptor and donor molecules, respectively. We isolated and characterized two major products from the reaction mixture. The structural analyses using 13C- and 1H-NMR spectroscopy proved that they were 4-hydroxyphenyl alpha-maltoside (alpha-Ab-alpha-G1) and 4-hydroxyphenyl alpha-maltotrioside (alpha-Ab-alpha-G2). Both alpha-Ab-alpha-G1 and alpha-Ab-alpha-G2 exhibited competitive-type inhibition on human tyrosinase as alpha-arbutin does. Their K(i) values were calculated to be 0.6 mM and 2.8 mM, respectively, which is slightly and significantly higher than that of alpha-arbutin (0.2 mM).     

Measurements of water distribution in through-plane direction of PEFC by using neutron radiography

Fuel gas (hydrogen gas) and oxidant gas (air) are supplied to a polymer electrolyte fuel cell (PEFC). Protons pass through the electrolyte membrane, and combine with oxygen to form water in the cathode reaction site. The generated water must be supplied appropriately to the membrane for proton conduction. On the other hand, the generated water may affect the fuel cell performances because of the blocking of oxygen from reaching the cathode reaction site. Therefore, water management in the PEFC is important, and water distribution during the operation in the through-plane direction has been of wide concern. In order to obtain the water distributions in a membrane electrode assembly (MEA) and a gas diffusion layer (GDL), a borescope system was newly employed using neutron radiography. The system could obtain the water distribution in the MEA and the GDL, and pixel size of 6.5 μm was achieved. Furthermore, the system was applied for a tilted converter system. The pixel of 1.0 μm at an angle of 81° was achieved, and improvement of the spatial resolution was confirmed.     

Measurement of water thickness in PEM fuel cells and analysis of gas velocity distributions

Fuel gas (hydrogen gas) and oxidant gas (air) are supplied to a polymer electrolyte fuel cell (PEFC). Condensation may occur in the cathode side, since the air might be super-saturated by the fuel cell reactions. If condensed water exists in a gas diffusion layer (GDL) or the gas channels, it may affect the fuel cell performances because it blocks the oxygen from reaching the cathode reaction site. Thus, water management in the PEFC is important. In order to clarify water effects on performances of a PEFC, visualization and quantitative measurements of water distributions in a PEFC were carried out by means of neutron radiography. Two-dimensional water distributions were obtained, and water ejection was confirmed. It was found that the water easily accumulated in the GDL under the rib rather than under the channel at beginning of the operation. Furthermore, a network analysis of gas-velocity distribution is applied for the experimental results. It analyzes the gas-velocity distributions depending on the flow resistance, which is the pressure drop. Applying the measured data of water thickness, gas-velocity distributions were obtained in the channel and the GDL. From the calculation, air supply in the GDL dramatically decreased with increasing of water accumulation.     

Fabrication and electrical properties of SrTiO3/diamond junctions

Strontium titanate (STO) films were directly deposited on Ib (100) single crystal diamond by r.f. magnetron sputtering. The as-deposited STO film was in amorphous state. On the other hand, the crystalline STO film was obtained under the optimized condition of a deposition temperature of 250 °C and a post-annealing temperature of 650 °C. STO/diamond junctions were fabricated on boron-doped homoepitaxial layers grown on p⁺-type single crystal diamond substrates. Electrical properties of the STO/diamond junction were investigated by changing the surface terminations of diamond with hydrogen or oxygen and the crystallinity of the STO film. It was found that the amorphous STO acted like a semi-insulator on H-diamond surface and that the amorphous STO/O-diamond junction behaved like a Schottky diode. The crystalline STO/O-diamond showed a complex rectifying behavior. The crystalline STO film possessed a higher dielectric constant as compared to that of the amorphous one.     

Defect reduction in Cu dual damascene process using short-loop test structures

This paper outlines the defect reduction measures performed during the development of a 130-nm Cu dual-damascene process. The test methodology, using short-loop test structures, included defect tracing, overlaying defect data and electrical measurement data, physical analyses based on these results, and analyses of defect size distribution. While the defect size distributions for large-scale integration processes are considered to depend on x/sup -k/, the distribution for the Cu dual-damascene process is found to be different and is instead characterized by a cumulative distribution described by the composition of several Lorentzian functions. Using these procedures, defect densities were successfully reduced by 50% in half the time taken previously and without the need for actual products.     

A numerical integration scheme for special finite elements for the Helmholtz equation

The theory for integrating the element matrices for rectangular, triangular and quadrilateral finite elements for the solution of the Helmholtz equation for very short waves is presented. A numerical integration scheme is developed. Samples of Maple and Fortran code for the evaluation of integration abscissæ and weights are made available. The results are compared with those obtained using large numbers of Gauss–Legendre integration points for a range of testing wave problems. The results demonstrate that the method gives correct results, which gives confidence in the procedures, and show that large savings in computation time can be achieved. Copyright © 2002 John Wiley & Sons, Ltd.