Effect of micro ploughing during fine particle peening process on the microstructure of metallic materials

In this study, the mechanism of microstructural changes induced by fine particle peening (FPP) treatment was analyzed. Ti–6Al–4V alloy specimens treated with FPP, using tool steel particles with a peening time ranging from 0.1 to 30 s were prepared and examined. Observation of the specimen with short-term FPP treatment revealed that two types of collision dents were formed by the micro abrasive behavior between collided particles and specimen surface. One was the “indented dent,” formed by particles that collided with the surface vertically, and the other was the “ploughed dent,” accompanied by a heap of piled-up material that was ploughed aside during the formation of this dent. Analyses using energy dispersive X-ray spectroscopy (EDS) revealed the presence of particle fragments transferred to the ploughed dents, although no fragments were observed on the indented dents. With an increase in peening time, transferred fragments were embedded into treated materials by deformed material due to a micro ploughing effect. The Fe-rich region became deeper as the particle fragments were embedded. Finally, a lamellar microstructure with a high concentration of Fe was formed by FPP treatment. The effects of micro ploughing during the FPP process on the lamellar modified microstructure formation were clarified. One effect was an enhancement of metal transfer from particles to substrate because virgin metallic surface was exposed; and the other was the mechanical mixing of transferred elements into the substrate.     

Spatial localization of stress-perturbing wave generated by anelectromagnetic acoustic transducer

A new apodization of electromagnetic acoustic transducer has been proposed to generate the stress perturbing wave, which has a spatially localized magnitude distribution. According to the acoustoelastic effect, a stress perturbing wave radiated into metals gives rise to an ultrasound velocity change that corresponds to the deviation of the stress in the metal. In ultrasonic measurements, it is desirable to use a narrow beam in order to obtain a high resolution. A transducer has been constructed which has a Sinc function apodization. To compare with other types of electromagnetic acoustic transducers, including a Limited Bessel-type transducer, numerical simulations are performed. It is shown that the proposed transducer provides the optimum characteristics of the spatially localized magnitude distribution. Furthermore, experimental results are presented to confirm the numerical predictions     

Multiple-valued radix-2 signed-digit arithmetic circuits forhigh-performance VLSI systems

VLSI-oriented multiple-valued current-mode MOS arithmetic circuits using radix-2 signed-digit number representations are proposed. A prototype adder chip is implemented with 10-μm CMOS technology to confirm the principle of operation. A multiplication scheme using four-input current-mode wired summations for realizing a high-speed small-size multiplier is presented. The 32×32-b multiplier is composed of 18800 transistors and required fewer interconnections. The multiply time is estimated to be 45 ns by SPICE simulation in 2-μm CMOS technology. It is shown that the technology is also potentially effective for the reduction of the data-bus area in VLSI     

TiO2 thin films using organic liquid materials prepared by Hot-Wire CVD method

TiO₂ thin films prepared by Hot-Wire CVD method have been studied as a protecting material of transparent conducting oxide (TCO) against atomic hydrogen exposures for the fabrications of Si thin film solar cells. It was found that electrical conductivity of the films at room temperature reached a value of 0.4 S/cm. This value is 2-3 orders of magnitude higher than that of TiO₂ films prepared by RF magnetron sputtering and electron-beam evaporation methods in our previous works. The conductivity improvement seems to be partly due to the enlargement of TiO₂ crystallites.     

Crystal orientation of poly(?-caprolactone) blocks confined in crystallized polyethylene lamellar morphology of poly(?-caprolactone)-block-polyethylene copolymers

The crystal orientation of poly(?-caprolactone) (PCL) blocks in PCL-block-polyethylene (PE) copolymers has been investigated using two-dimensional small-angle X-ray scattering (2D-SAXS) and 2D wide-angle X-ray diffraction (2D-WAXD) as a function of crystallization temperature T_c and thickness of PCL layers d_PCL. The PCL blocks were spatially confined in the solid lamellar morphology formed by the crystallization of PE blocks (PE lamellar morphology), an alternating structure of crystallized PE lamellae and amorphous PCL layers. This confinement is expected to be intermediate between hard confinement by glassy lamellar microdomains and soft confinement by rubbery ones, because the crystallized PE lamellae consist of hard PE crystals covered with amorphous (or soft) PE blocks. The 2D-SAXS results showed uniaxial orientation of the PE lamellar morphology after applying the rotational shear to the sample. Therefore, it was possible to investigate crystal orientation of PCL blocks within the oriented PE lamellar morphology. The 2D-WAXD results revealed that the c axis of PCL crystals (i.e., stem direction of PCL chains) was parallel to the lamellar surface normal irrespective of T_c when 16.5 nm ≥ d_PCL ≥ 10.7 nm. However, it changed significantly with changing T_c when d_PCL = 8.8 nm; the c axis was perpendicular to the lamellar surface normal at 45 °C ≥ T_c ≥ 25 °C while it was almost random at 20 °C ≥ T_c ≥ 0 °C. These results suggest that the PE lamellar morphology plays a similar role to glassy lamellar microdomains regarding spatial confinement against subsequent PCL crystallization.     

Effect of Surface Treatment on the Selective Photocatalytic Oxidation of Benzyl Alcohol into Benzaldehyde by O2 on TiO2 Under Visible Light

The photocatalytic oxidation of benzyl alcohol into benzaldehyde proceeded with high conversion and selectivity on a TiO₂ photocatalyst by O₂ under visible light irradiation. Surface complex formed by the interaction of benzyl alcohol with the Ti sites and/or surface OH groups of TiO₂ play an important role in the absorption of visible light and unique selective photocatalytic reaction.     

Effect of Support Materials on the Selective Methanation of CO over Ru Catalysts

Selective methanation of CO in the reformate gas (CO/CO₂/H₂/H₂O = 0.175/17.9/70.9/11.1) proceeded over Ru catalysts supported on metal oxides and zeolites. CO was selectively methanated at wide temperature ranges (200–275 °C) over Ru/γ-Al₂O₃, Ru/TiO₂ Ru/H-Y and Ru/H-beta catalysts. Higher Ru contents in Ru/γ-Al₂O₃ improved the selective CO methanation rate.     

The use of a virtual city model for assessing equity in access to views

The development of virtual city models has provided novel possibilities for analyses that require consideration of building heights in urban areas. The study was undertaken to explore these possibilities by using the virtual Kyoto model to examine equity in access to views in the Japanese city. A sample of just over 5000 residences was selected by stratifying for population age and affluence. A series of viewsheds were computed to quantify the visibility of a range of environmental amenities (greenspaces, water bodies, historical buildings, mountains) and disamenities (factories and roads). Evidence of inequity in visual amenity was identified, whereby homes in areas with many old people were much less likely to have views of greenspaces and water bodies, although they were also less likely to see factories and roads and were more likely to view mountains. Homes in more affluent areas had better views of greenspaces, historical buildings, and mountains, and were less likely to see factories and water bodies. We discuss the potential of virtual city models for furthering analyses of the urban environment and raise some caveats regarding their use.     

Alternating copolymers of carbon dioxide with glycidyl ethers for novel ion-conductive polymer electrolytes

To overcome the low ionic conduction of existing poly(ethylene oxide)-based polymer electrolytes, we consider polycarbonates obtained from the copolymerization of CO₂ and epoxy monomers. We synthesized four types of polycarbonates possessing phenyl, n-butyl, t-butyl and methoxyethyl side groups using zinc glutarate, and measured the ionic conductivity of their electrolytes, including 10 mol% of LiTFSI. The electrolyte possessing methoxyethyl side groups had the highest conductivity, of the order of 10⁻⁶ S cm⁻¹ at room temperature. The activation energy (E_a) for ionic conduction in the polycarbonate electrolytes was estimated from the VTF equation, and the E_a of the electrolyte possessing n-butyl side groups was almost the same with the polyether-based electrolytes. An interesting feature of our study is that the polycarbonate is a unique candidate for ion-conductive polymers because of its flexible and hydrophobic properties.