Study on sustainable redevelopment of a densely built-up area in Tokyo by introducing a distributed local energy supply system

“Distributed local energy systems” had been expected to rationalize the supply of energy to built-up areas, but until now very little research has been performed to estimate the effect of their application to actual cities. In this research, therefore, a future vision for the year 2030 in the Sancha Area (SANCHA VISION 2030), a typical densely built-up area in Tokyo, has been elaborated including a simulation to estimate benefits from the application of distributed energy systems in terms of reduced energy consumption and CO₂ emissions as well as mitigation of the heat-island phenomenon. As a result, it was demonstrated that a “distributed local energy system”, which provides a district with both electrical power and heat through an integrated distribution system, may contribute to a considerable improvement in energy efficiency for those areas. In addition, it may also provide other benefits, including enhancement of living amenity and urban security in times of emergency.     

The fabrication and thermomechanical behavior of Al and Ti SMA composites

Two kinds of composites—Ti-Ni shape-memory alloy (SMA) fiber-reinforced 6061 aluminum matrix composite and Ti-Pd(Ni) SMA-reinforced titanium-matrix composite—were fabricated by various processing methods and their microstructure and thermomechanical behavior were investigated. In both sets of composites, an increase in yield stress at high temperature was mainly caused by residual compressive stress created in the matrix in association with shape-memory effects of the embedded SMAs. For more information, contact Kiyoshi Mizuuchi, Osaka Municipal Technical Research Institute, Osaka 536-8553, Japan; e-mail: mizuuchi@omtri.city.osaka.jp.     

Sinterability of various high-purity magnesium oxide powders

The sinterability of high-purity MgO powders with different production histories was investigated to make clear the relationship between the powder characterization, the densification processes, and the changes in microstructure both with increasing temperature at a rate of 10° C min^–1 and at a fixed temperature of 1450° C for 5 h. The densification behaviour and the changes in microstructure of these compressed bodies were affected chiefly by their original surface activity and degree of agglomeration, depending on the production histories: (i) the ultra-fine and well-dispersed powder prepared by the vapour-phase oxidation process showed that densification proceeded with an appreciable grain growth with few closed pores remaining; (ii) powder derived from the sea-water magnesia process showed that the densification behaviour was affected by the species of magnesium salt, i.e. basic magnesium carbonate or magnesium hydroxide, used as a precursor; however, whichever magnesium salt was used, its sintered compact showed similar closed porosities and grain-size distributions; (iii) powder derived from the spark-discharge process contained skeletons of the original Mg(OH)₂ particles; however, the densification proceeded gradually with slow grain growth, reflecting the fact that the powder has a moderate surface area (36 m² g^–1). The sintered compact from (iii) had a small closed porosity and the smallest grain-size distribution among the compacts used in this investigation.     

Effect of transition elements on the properties of MC carbides in IN-100 nickel-based superalloy

The effect of nine transition elements on the morphology, distribution and composition of MC carbides (MCs) in a nickel-base superalloy, IN-100, was investigated by differential thermal analysis (DTA), microstructural observation and X-ray microanalysis. The doping with tantalum, tungsten and molybdenum caused a significant change in the morphology and distribution of MCs as well as the profile of DTA curve of IN-100. The compositions of the MC in IN-100 were TiC and (Ti_0.80Mo_0.17V_0.03) C, and the doping with niobium, tantalum and tungsten changed significantly the composition of MC. On the other hand, the doping with chromium, vanadium, hafnium and zirconium scarcely changed the composition. In addition to TiC and (Ti, Mo, V) C, zirconium- and hafnium-rich MCs were found in the zirconium- and hafnium-doped alloys, respectively. The effect of the dopants on the composition of MCs could be explained by a relationship between the metallic radius and the free energy of formation for the MC.     

A New Silicon Sensor for Hot Metal Measurements

In the present study, an electrochemical sensor has been designed for the direct measurement of silicon content in hot metal. The sensor represents a galvanic silicon concentration cell of the type Ni_sat—Si(1) II silicate electrolyte (1) II Fe—C—Si(1) The tubular silica-glass sensor can be immediately immersed into the metal bath at a response time of 30 to 60 s. A reproducible EMF vs. wt.% Si relationship was obtained for measurements in carbon-saturated Fe—C—Si melts at 1400°C and Si contents from 0.05 to 1.8 wt.%. This relationship is nearly identical with the cell function calculated from thermodynamic data.     

Three-dimensionally ordered macroporous polyimide composite membrane with controlled pore size for direct methanol fuel cells

Three-dimensionally ordered macroporous (3DOM) polyimide matrix with different pore size (1.3 μm–200 nm) was fabricated, and its structural effect on some properties of composite membrane was investigated. The composite membrane prepared by impregnation of 2-acrylamido-2-methylpropanesulfonic acid polymer (PAMPS) exhibited swelling ratios as low as 2–3% in water or methanol solutions, compared with about 400% of PAMPS itself. The swelling ratio of composite membrane was constant regardless of the 3DOM pore size. However, methanol permeability strongly depended on the pore size. In particular, it was drastically reduced when connecting windows among macropores became less than 100 nm. On the other hand, proton conductivity changed with 3DOM matrix porosity according to Archie's law. The porosity of 3DOM matrix is basically constant even if the pore size changes. Therefore, we suppressed the methanol crossover without lowering of proton conductivity due to reducing the matrix pore size, and the selectivity (proton conductivity/methanol permeability) of 1.2 × 10⁵ S cm⁻³ s, which was one order of magnitude greater than that of Nafion^®, was achieved.     

Decomposition and regeneration of methane in the absence and the presence of a hydrogen-absorbing alloy CaNi5

Suitable catalysts for the decomposition of methane into carbon and hydrogen and for the regeneration of methane by hydrogenation of the carbon have been looked for in a series of transition metals and precious metals supported on various carriers. The most active catalyst for both reactions was Ni/SiO₂. The carbon formed on this catalyst was thermodynamically less stable than graphite. The different rate equations for the decomposition of methane obtained for the fresh and carbon deposited Ni/SiO₂ suggest that the rate-determining steps are different for the two catalysts. The highest number of carbon atoms deposited per one Ni atom was 31 at 773 K. However, the number of methane molecules recovered easily at 773 K was limited to 1.5 per Ni atom.

A physical mixture of Ni/SiO₂ and CaNi₅, a hydrogen-absorbing alloy, enhanced the decomposition rate of methane, enabling the complete conversion of methane at 773 K beyond the thermodynamic limitation. The presence of CaNi₅ at 273 K separated from the catalyst in a reaction system further enhanced the decomposition of methane due to an increased hydrogen-absorbing capacity of the CaNi₅ at low temperatures. The carbon deposited on Ni/SiO₂ in this case was reactive to be hydrogenated back to methane at 773 K, giving an average 7.5 CH₄ molecules per one Ni atom.     

Reduction of in vitro allergenicity of buckwheat Fag e 1 through the Maillard-type glycosylation with polysaccharides

A major allergenic protein of buckwheat, Fag e 1 prepared from common buckwheat (Fagopyrum esculentum), was covalently linked with food-grade polysaccharides, arabinogalactan or xyloglucan through the controlled dry-heating at 60 °C under 65% relative humidity. The introduction of polysaccharide chain onto the molecular surface of Fag e 1 reduced the allergenicity of Fag e 1. The results revealed that the Maillard-type glycosylation of Fag e 1 with polysaccharides brought about a drastic reduction of the reactivity against human sera of buckwheat-allergy subjects, using immuno dot-blotting, QCM analysis and ELISA. In addition, the glycosylation of Fag e 1 yielded a great improvement of its surface functionality. Solubility of Fag e 1 at the neutral pH was substantially increased up to 13.5 times and 9.6 times by the conjugation with arabinogalactan and xyloglucan, respectively. Emulsifying properties of Fag e 1 were also improved by the glycosylation, of which both emulsifying activity and emulsion stability were more than 6 times higher than those of the native protein.     

Carbon nanofibers with radially oriented channels

An easy templateless method to synthesize porous carbon nanofibers (CNFs) having radially-oriented mesopores is reported, using selective gasification with nano-sized catalyst particles and hydrogen as the gasification reagent. The gasification generated pores whose size corresponds to that of the catalyst particle used for the drilling. The pores were formed along the graphitic layers, reflecting the structural alignment in the CNFs. The pore size and structure can be controlled by selection of catalyst and gasification conditions.     

A corrosion prediction method for weathering steels

Japanese Specification for Highway Bridges [Japan Road Association: Specification for Highway Bridges—I & II, 2002.3] has been revised in 2002, which clearly states that degradation of bridge members, including those of weathering steels, to occur in prolonged period of time must be taken into account at the design stage to realize long term structural durability. To cope with the revised paradigm, SABI chemistry committee in Japan Society of Corrosion Engineers has proposed durable state concept [SABI Chemistry Committee of Japan Society of Corrosion Engineers, in: Proc. 132nd Symposium for Corrosion and Protection, 2001.6.25, p. 3], which is defined as a condition in which corrosion rate of steel is slow enough not to form thick rust [H. Kihira, K. Shiotani, H. Miyuki, T. Nakayama, M. Takemura, Y. Watanabe, Doboku Gakkai Ronbun-shu (J. Japan Soc. Civil Engineers) No. 745/I-65, 2003.10, pp.77-87]. Since corrosiveness of atmosphere differs by location, a corrosion prediction method for both conventional and advanced weathering steels [H. Kihira, A. Usami, K. Tanabe, M. Ito, G. Shigesato, Y. Tomita, T. Kusunoki, T. Tsuzuki, S. Ito, T. Murata, in: Electrochemical Society Proceedings, vol. 99-26, 2000, pp. 127-136] is needed to ensure structural durability for future. Thus, versatile computational scheme for it has been derived through mathematical modeling based upon the durable state concept.