Five-year measurements of thermal performance for a semi-underground test house

In order to obtain fundamental data on the thermal performance of a semi-underground room, a twin-type test house was constructed on the campus of Tohoku University in September 1984. The test house has two rooms with south-facing windows above the ground surface, and a corridor between the two rooms. The floor level is 1.3m below the ground surface. Thermal insulation 0.1m deep and 1.35m wide was installed horizontally around the room on the east at a level 0.3m below the ground surface. The room on the west has no such “horizontal” insulation. Five-year measurements of air temperatures in both rooms, soil temperatures around the rooms, energy consumption for space heating, and so forth were made in four different situations. An experimental study found that horizontal insulation was effective in reducing the annual temperature fluctuation of indoor air, and in reducing the heating load. These effects, which were also analyzed from the viewpoint of heat balance in the room, were verified by computer calculations based on the two-dimensional finite element method.     

Selective Hydrocracking of Fischer–Tropsch Waxes to High-quality Diesel Fuel Over Pt-promoted Polyoxocation-pillared Montmorillonites

Polyoxocation ([AlO₄Al₁₂(OH)₂₄(H₂O)₁₂]⁷⁺ and [Zr₄(OH)₁₄(H₂O)₁₀]²⁺)-pillared montmorillonites were prepared by ion exchange, and they were used as solid acid catalysts, in comparison to some other solid acids, for the selective hydrocracking of Fischer–Tropsch waxes to diesel-ranged hydrocarbons. XRD patterns and elemental analyses proved that the polyoxocations were successfully introduced into the interlayer region of the montmorillonites. N₂ adsorption–desorption measurement indicated that polyoxocation-pillared montmorillonites have large BET surface areas (>230 m² g^?1), high thermal stability (>673 K), and large pores (comparing to those in zeolites). FT-IR spectra of chemisorbed pyridine indicated that polyoxocation-pillared montmorillonites possess both Lewis and Bronsted acid sites on the solid surface. Temperature-programmed desorption of ammonia indicated that the acidity strength of the polyoxocation-pillared montmorillonites was weaker than those of H–ZSM-5, H–Y, WO₃/ZrO₂, and Al₂O₃–SiO₂. In the hydrocracking of Fischer–Tropsch (F–T) waxes, the acidity strength of the solid acids in bifunctional catalysts greatly influences the product composition. Pt-promoted H–Y afforded a high yield of gasoline-ranged hydrocarbons (>90%) while Pt-promoted H–ZSM-5 afforded a larger amount of gas products due to its strong solid acid sites. On the other hand, among various catalysts, Pt-modified polyoxocation-pillared montmorillonites afforded the highest yield of diesel-ranged hydrocarbons (>70%) due to the appropriately weak acid strength, high thermal stability, large BET surface area, and large pore size. Pt is necessary for the hydrocracking of F–T waxes because it enables hydrogenation/dehydrogenation. However, a high Pt loading on the catalyst produces more light hydrocarbons due to the stimulation of hydrogenolysis. High hydrogen pressure improved the selectivity for diesel-ranged hydrocarbons but decreased the conversion of F–T waxes due to the suppression of alkane dehydrogenation. The hydrocracking of F–T waxes at a low temperature with a large amount of catalyst for longer reaction time increased the yield of diesel-ranged hydrocarbons.     

Analysis of regiospecific distribution of FA of TAG using the lipase-catalyzed ester-exchange

A very simple and versatile GC method has been developed that can be utilized for quick analysis, in many samples, of the FA compositions at the sn-2- and sn-1,3-positions of TAG. By using the lipase-catalyzed, sn-1,3-regioselective esterexchange reaction of TAG with ethyl acetate, followed by direct injection of the crude reaction mixture into the GC apparatus without any pretreatment, the FA located at the sn-2-position could accurately be analyzed as a TAG derivative in which the sn-1,3-positions were substituted by an acetate residue. Furthermore, the FA located at the sn-1,3-positions could simultaneously be analyzed as the corresponding ethyl ester derivatives using this method. The reliability of the analytical method was compared with conventional methods by analyzing the TAG consisting of caprylic acid (C) at the sn-2-position and oleic acid (O) at the sn-1,3-positions, giving comparable analytical results. The present method was applied to the analysis of the structured lipids CCD and CCE, consisting of TAG as a major component in which C and the highly unsaturated FA, DHA (D) or EPA (E), were specifically bound at the sn-2- and the sn-1,3-positions, respectively.     

Friction stir spot welding of aluminium to steel by rotating tool without probe

A friction stir spot welding process, in which a rotating tool without a probe was employed, was applied to a lap joint of an aluminium plate to a low carbon steel plate. The thicknesses of both plates were 0.5 mm. In this process, the rotating tool of 5 mm diameter, rotating at 18,000 rpm, was plunged into the aluminium plate at a rate of 2 mm/s, and then kept at a maximum plunged depth of 0.05–0.35 mm for 0–2 s (dwell time). In the weld obtained by this process, a hole due to the impression of the penetrated tool probe was not formed, although a slight depression by the tool plunging remained. At tool plunge depths of 0.1 mm or over, it was possible to weld the two plates. The maximum tensile failure load of 454 N was obtained at a plunge depth of 0.1 mm and a dwell time of 1.5 s. Its joint was fractured at an almost constant load along the periphery of the depression, leaving a part of the aluminium plate on the steel plate surface. Based on the observation of the weld interface microstructure and metal flow of aluminium in the weld, controlling factors of the joint strength were discussed.     

为新发动机新气门可变动作角与升程(VVEL)机构开发的新粉末冶金零件

这2个粉末冶金零件是日产汽车公司藤木章教授等新近研发的用于V6发动机的重要零件。曾荣获日本粉体粉末冶金协会第二次(2009年度)新技术新制品奖,承蒙日本粉体粉末冶金协会准予本刊译为中文刊载,特向日本粉体粉末冶金协会致谢,并向相关业者予以介绍。     

The relation between melt flow properties and molecular weight of polyethylene

The non-Newtonian behavior of commercial linear polyethylene samples and their fractions were studied at 190°C. The viscosity η versus shear rate \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} curves of whole polymers could be superimposed onto a single master curve despite the variations of their molecular weights and molecular weight distributions. For fractions, however, the same master curve was inapplicable, and the sensitivity of the viscosity to shear rate was found to be greater than those of the whole polymers. The zero-shear viscosities η₀ of fractions were related to the 3.42 power of the weight-average molecular weight M_u as follows: For whole polymers, the zero-shear viscosities were found to be considerably higher at the same M_w and markedly lower at the same z-average molecular weight M_z than those of the fractions. Thus, it was concluded that η₀ corresponds to an average of molecular weight between M_w and M_z. It was found that the molecular relaxation time τ is proportional to M_z^5.3 for whole polymers and to η₀M_w for fractions. Using these relations it was possible to relate the flow ratio, the ratio of flow rates at two different shear stresses, with the molecular weight distribution.     

Controllability of arc jet from arc horns with slits

Ultrahigh-voltage transmission lines must be protected from lightning surges and the large-current fault arcs which follow. Horns which are installed at the jumpers on the strain towers have a role in protecting the insulators from the fault arcs by coordinating insulation strength and holding large-current fault arcs between the horns. Although a flat surface of the electrode tip with a small diameter effectively meets these requirements, it results in the deterioration of corona discharge depressing capabilities in a steady state on power transmission lines. To improve corona discharge depressing capabilities and to reduce deflection of arc jets, finally two types of hemispherical-shaped arc horn electrodes with slits are developed. The arc jet control performance of those horns was disclosed experimentally as follows:

• (1) Two types of arc horn electrodes with our or six slits show remarkable arc jet control performance in the current of larger than 5 kA.
• (2) The addition of a rod-type central electrode at the center of the hemispherical-shaped electrodes results in the considerable extension of arc jet controllability in the wider current zone by containing the arc spot within the tip area of the central electrodes.

Based on the foregoing results, arc horn electrodes with slits have been designed and utilized for practical application.     

Production of aldehyde oxidases by microorganisms and their enzymatic properties

In order to establish an efficient process to decompose environmentally toxic aldehydes, dioxygen-dependent aldehyde oxidase (ALOD) from microorganisms was first sought, and some bacteria and actinomycetes were found to produce the enzyme in their cells. Methylobacillus sp., Pseudomonas sp. and Streptomyces moderates were selected as the representative ALOD-producing strains and their enzymes were partially purified and characterized. The three ALODs could oxidize a wide range of aldehydes including formaldehyde, aliphatic aldehydes, and aromatic aldehydes, though their preferences differ depending on their producing strains. The other enzymatic properties were also determined with regard to their producing strains. Methylobacillus sp. ALOD had the most acidic optimum pH for its activity and stability and Pseudomonas sp. ALOD had the highest stability against heat treatment. Three native ALODs had molecular weights ranging from 140 to 148 kDa and were composed of three subunits of different sizes: large (85 to 88 kDa), medium-sized (37 to 39 kDa) and small (18 to 23 kDa).