Search

“Akahoya” is a volcanic soil classified as a special soil deposited in Kyushu, Japan. Many of its properties are not yet clearly understood. We found that Akahoya had the potential to adsorb bacteria in cattle feces, which prompted us to investigate its material properties and perform experiments to comprehensively evaluate its adsorption performance for various fine particles such as acidic and basic dyes, NOx/SOx gas, and phosphoric acid ions, in addition to bacteria. Akahoya had a very high specific surface area owing to the large number of nanometer-sized pores in its structure; it exhibited a high adsorption capacity for both NO2 and SO2. Regarding the zeta potential of Akahoya, the point of zero charge was approximately pH 7.0. The surface potential had a significant effect on the adsorption of acidic and basic dyes. Akahoya had a very high cation exchange capacity when the sample surface was negatively charged and a high anion exchange capacity when the sample surface was positively charged. Akahoya also exhibited a relatively high adsorption capacity for phosphoric acid because of its high level of Al2O3, and the immersion liquid had a very high Al ion concentration. Finally, filtration tests were performed on Escherichia coli suspension using a column filled with Akahoya or another volcanic soil sample. The results confirmed that the Escherichia coli adhered on the Akahoya sample. The results of the Escherichia coli release test, after the filtration test, suggested that this adhesion to Akahoya could be phosphorus-mediated.

The cleaning action in AC TIG welding is attributed to the oxide film removal process caused by cathode spots. Clarifying the behavior mechanism of these cathode spots will enable the control of the cleaning action. However, the behavior mechanism of cathode spots has not yet been experimentally clarified. This study reports that observations by high-speed video camera revealed the absence of cathode spots at the center of the molten pool, when shot in the vicinity of a molten pool after AC TIG welding using helium as shield gas on aluminum plates.

We investigated the use of waste glass fiber-reinforced plastic (GFRP) to remove dye from industrial wastewater. The dye adsorbent material, based on GFRP/clay ceramics, was produced by mixing crushed GFRP with clay and firing the resulting mixture. Several types of ceramics were produced by adjusting the mixing ratio of clay, crushed 40% GF/GFRP, and firing atmosphere. Adsorption tests with methylene blue (MB) dye were performed by mixing the ceramics into an MB solution while controlling the stirring speed and measuring the decrease in MB dye concentration over time. These results showed that GFRP/clay ceramics reductively fired at 1073 K had a higher MB dye adsorption ability than that of the clay ceramic. The MB dye absorptivity of the reductively fired ceramics increased as we increased the mixing ratio of GFRP. We attribute this result to the high plastic carbide content in the ceramic, which has excellent dye absorbability. Furthermore, these particles had a comparatively high specific surface area and porosity.

This study aims at development of a cost-effective, floating offshore wind turbine. The prototype model considered herein is composed of (1) 2-MW horizontal-axis wind turbine (HAWT) of downwind type, (2) steel monotower with 55-m hub height above sea level, (3) steel-prestressed concrete (PC) hybrid SPAR-type foundation with 70-m draft, and (4) catenary mooring system using anchor chains. In order to demonstrate the feasibility of the concept, an at-sea experiment using a 1/10-scale model of the prototype has been made. The demonstrative experiment includes (1) construction of the hybrid SPAR foundation using PC and steel, the same as the prototype; (2) dry-towing and installation to the at-sea site at 30-m distance from the quay of the Sasebo shipbuilding yard; (3) generating electric power using a 1 kW HAWT; and (4) removal from the site. During the at-sea experiment, wind speed, wind direction, tidal height, wave height, motion of the SPAR, tension in a mooring chain, and strains in the tower and the SPAR foundation have been measured. Motion of the SPAR has been numerically simulated and compared with the measured values, where basically good agreement is observed.

This study aims at development of a cost-effective floating offshore wind turbine. The proto-type model considered herein is composed of 1) 2MW horizontal-axis wind turbine (HAWT) of down-wind type, 2) steel mono-tower with 55m hub height above sea level, 3) steel-prestressed concrete (PC) hybrid SPAR-type foundation with 70m draught, and 4) catenary mooring system using anchor chains. In order to demonstrate the feasibility of the concept, on-sea experiment using a 1/10 scale model of the prototype has been made. The demonstrative experiment includes 1) construction of the hybrid SPAR foundation using PC and steel as same as the prototype, 2) dry-towing and installation to the on-sea site at 30m distance from the quay of the Sasebo shipbuilding yard, 3) generating electric power using a 1kW HAWT, and 4) removal from the site. During the on-sea experiment, wind speed, wind direction, tidal height, wave height, motion of the SPAR, tension in a mooring chain, and strains in the tower and the SPAR foundation have been measured. Motion of the SPAR has been numerically simulated and compared with the measured values, where basically good agreement is observed.Copyright © 2010 by ASME