Effects of Mg substitution on crystal structure and hydrogenation properties of Pr1−xMgxNi3

The effects of substitution of Pr by Mg in PrNi₃ with a PuNi₃-type structure were investigated using pressure–composition (P–C) isotherm measurements and X-ray diffraction. The unit cell of Pr_0.68Mg_0.32Ni_3.04 contracted anisotropically in comparison to that of PrNi₃. The maximum hydrogen capacity of PrNi₃ reached 1.25 H/M in the first absorption. A plateau region was observed between 0.82 H/M and 1.04 H/M in the first absorption cycle. However, 0.85 H/M of hydrogen remained in the sample after the first full desorption. Pr_0.68Mg_0.32Ni_3.04 showed reversible hydrogenation properties. The maximum hydrogen capacity was 1.22 H/M. The plateau region of Pr_0.68Mg_0.32Ni_3.04 was between 0.08 H/M and 0.87 H/M, which was wider than that of PrNi₃. Pr_0.68Mg_0.32Ni_3.04 retained the PuNi₃-type structure after hydrogenation, whereas the crystal structure of PrNi₃ changed from that of PuNi₃-type to an unknown structure. The structural change in PrNi₃ during hydrogenation was evidently different from that in Pr_0.68Mg_0.32Ni_3.04.     

Thin-film quasi-SOI power MOSFET fabricated by reversed siliconwafer direct bonding

A quasi-SOI power MOSFET has been fabricated by reversed silicon wafer direct bonding. In this power MOSFET, the buried oxide under the channel and source regions is removed and the channel region is directly connected to the source body contact electrode to reduce the base resistance of the parasitic npn bipolar transistor. The quasi-SOI power MOSFET can suppress the parasitic bipolar action and shows lower specific on-resistance than that of the conventional SOI power MOSFET. The fabricated chip level quasi-SOI power MOSFET shows the specific on-resistance of 86 mΩ·mm² and on-state breakdown voltage of 30 V     

A circuit design of intelligent cache DRAM with automaticwrite-back capability

An intelligent cache based on a distributed architecture that consists of a hierarchy of three memory sections-DRAM (dynamic RAM), SRAM (static RAM), and CAM (content addressable memory) as an on-chip tag-is reported. The test device of the memory core is fabricated in a 0.6 μm double-metal CMOS standard DRAM process, and the CAM matrix and control logic are embedded in the array. The array architecture can be applied to 16-Mb DRAM with less than 12% of the chip overhead. In addition to the tag, the array embedded CAM matrix supports a write-back function that provides a short read/write cycle time. The cache DRAM also has pin compatibility with address nonmultiplexed memories. By achieving a reasonable hit ratio (90%), this cache DRAM provides a high-performance intelligent main memory with a 12 ns(hit)/34 ns(average) cycle time and 55 mA (at 25 MHz) operating current     

A new solid model HSM and its application to interference detection between moving objects

In order to realize collision-free coordination of multiple robots, it is crucial to model the robots in a computer adequately and to detect existence or nonexistence of an interference between them on the basis of data structure of the robot models. Motivated by this observation, this article proposes a new solid model named “Hierarchical Sphere Model” (HSM) for modeling moving objects (robots) and presents a feasible algorithm for checking an interference between them on the basis of HSM. HSM arranges region informations in a hierarchical tree structure whose nodes correspond to spherical regions. On the basis of hierarchy of HSM, the algorithm checks only intersections between HSMs' nodes which are close to each other, and hence it works efficiently even if the objects have complicated shape. Furthermore, because a node of HSM represents a spherical region, intersection between, two nodes can be easily found just by calculating the distance between two spheres corresponding to them no matter how the objects move. Finally, the efficiency of the algorithm is demonstrated by several experiments.     

Development of railgun accelerator at the institute of space and astronautical science (ISAS)

This paper describes the current status of the development of electromagnetic launchers such as the railgun at ISAS. The railgun is the most improved accelerator of Electromagnetic Launchers (EML). EML offers a potential for accelerating a projectile to much greater velocities than achieved with conventional powder guns or light gas guns. However, there has been little progress in increasing the velocity of EMLs since the experiment by Rashleigh and Marshall. A few experiments have been reported achieving velocities greater than 6km/s. The authors have achieved velocities greater than 6 km/s by reducing plasma leakage which is one of the factors limiting velocity. In this paper a 6 km/s launch is reported, compared with the results of two other shots considered from the viewpoint of plasma leakage, and the effect of entrainment of eroded material into the armature by rail ablation was discussed on the basis of simulated numerical calculations.     

Electrochemical polymerization of pyrrole in supercritical carbon dioxide-in-water emulsion

Supercritical carbon dioxide is an environmentally benign solvent but its low polarity limits electrochemical reactions in it. We now report the electrochemical polymerization of pyrrole in a supercritical carbon dioxide-in-water (C/W) emulsion in the presence of a surfactant. Black polypyrrole films were formed on Pt electrodes, whose conductivity was comparable with non-oriented polypyrrole prepared in conventional solvents. The structure of the polypyrrole films was confirmed by IR and Raman spectroscopic measurements. p-Toluenesulfonic acid was a suitable supporting electrolyte among the electrolytes examined for the electrochemical polymerization in the C/W emulsion. A typical nodular morphology was observed on the basis of the SEM and AFM measurements. Confocal scanning microscope revealed the formation of a fine uneven texture on the film prepared in the C/W emulsion.     

Dimeric components from the dimerization of abietic acid

Capillary gas-liquid chromatography of the product formed by sulfuric acid-catalyzed dimerization of abietic acid showed the presence of some 40 dimeric components. The three major components were isolated and shown to be heptacyclic dimers, two of which had a conjugated double bond system. The other component had two nonconjugated double bonds. Also isolated were three dimers consisting of monomers attached through a single carbon-carbon bond: one carboxyl group in each of these dimers was in the form of a γ-lactone. Maintained in cooperation with the University of Wisconsin.     

The Effect of Chemical Composition and Heat Treatment Conditions on Stacking Fault Energy for Fe-Cr-Ni Austenitic Stainless Steel

In order to establish more reliable formulae for calculating stacking fault energies (SFE) from the chemical compositions of austenitic stainless steels, SFE values were measured for 54 laboratory-melted heats and 2 commercial heats. The results were checked against those of a first-principle, atomistic calculation approach. More than ~20,000 data points for the width and angle of the Burgers vectors were determined from dark-field images of isolated extended dislocations in 56 heats of austenitic stainless steel using weak electron beams with g-3g diffraction conditions. Based on these numerous observations and on fundamental thermodynamic analyses, it is concluded that the SFE values for austenitic stainless steels are changed not only by chemical composition but also by heat treatment. In this paper, new formulae for calculating SFE values from the chemical compositions in three different heat treatment conditions have been proposed for austenitic stainless steels within given limited chemical composition ranges. In these formulae, the SFE values are calculated from the nickel, chromium, molybdenum, silicon, manganese, nitrogen, and carbon contents for the each heat treatment condition. The three heat treatment conditions studied were water cooling after solution heat treating (SHTWC), furnace cooling after solution heat treating, and aging after SHTWC.     

Paradigms representing the relationship between the inner of a brain and the outer world

Neuroscience was initially based on simple computer models, and the resulting assumption of blocks of information and step‐by‐step information processing disregards the dynamic features of living neuronal networks. Building semiartificial intelligence in a culture dish using a simple living neuronal network makes comparison with an engineering model easier than when analyzing a complicated brain network. We hypothesize that the status of the neuronal network changes autonomously according to both its own internal state and input from the outer world. Our investigation of such network suggests that an electrical stimulus can make the living neuronal network shift to a particular state, and the response pattern to each input is loosely coupled rather than strictly linked. The critical point we propose regarding brain‐like information processing is that the internal state of the autonomous neuronal network is modified by input from the outer world. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Large-size multi-crystalline silicon solar cells with honeycomb textured surface and point-contacted rear toward industrial production

In this paper, we present a multi-crystalline solar cell with hexagonally aligned hemispherical concaves, which is known as honeycomb textured structure, for an anti-reflecting structure. The emitter and the rear surface were passivated by silicon nitride, which is known as passivated emitter and rear (PERC) structure. The texture was fabricated by laser-patterning of silicon nitride film on a wafer and wet chemical etching of the wafer beneath the silicon nitride film through the patterned holes. This process succeeded in substituting the lithographic process usually used for fabricating honeycomb textured structure in small area. After the texturing process, solar cells were fabricated by utilizing conventional fabrication techniques, i.e. phosphorus diffusion in tube furnace, deposition of anti-reflection film and rear passivation film by chemical vapor deposition, front and rear electrodes formation by screen printing, and contact formation by furnace. By adding relatively small complicating process to conventional production process, conversion efficiency of 19.1% was achieved with mc-Si solar cells of over 200 cm² in size. The efficiency was independently confirmed by National Institute of Advanced Industrial Science and Technology (AIST).