An analysis of shielding against DC magnetic fields generated by electric railways. Evaluation of effective permeability of fine structure

This paper describes an effective analysis of magnetic shielding based on homogenization. The analyses become time‐consuming if the problems include the magnetic substances having fine structure. The homogenization of the structure makes it possible to analyze effectively the magnetic fields. The authors introduce a method to estimate the effective permeability of the homogenized substance. This method can be applied to any periodic structure made of magnetic substance. The magnetic shielding effects by the structures against direct‐current (DC) fields generated by electric railways are analyzed by using the present method. As a result, it is found that the overhead way and the protective fence near the railway work as a magnetic shield, whose effects can be improved by appropriate arrangement of those constructions. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 7–15, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20310     

The role of repeat transurethral resection in stage A1 carcinoma of the prostate

In order to evaluate the significance of repeat transurethral resection (TUR) in differentiating stage A1 prostatic adenocarcinoma from those with stage A2, we performed repeat TUR in 34 patients with an initial diagnosis of stage A1 prostatic adenocarcinoma. It was found that residual adenocarcinoma was present in five cases (14.7%), but the diagnosis was changed from stage A1 to stage A2 in only one case (2.9%). In one patient with final diagnosis of stage A1 carcinoma, bone metastases were detected seven months after the repeat TUR. It was concluded that repeat TUR for stage A1 prostatic adenocarcinoma did not yield clinically significant information.     

Authorship and citation patterns in Management Science in comparison with operational research

The authorship and citation patterns in the journal titled Management Science (MS) are analysed. The purpose of the analysis is to examine the competitive relation of MS with OR (operational research or operations research). The analysis is focused on the use of mathematical methods, because MS entered the management research area by using mathematical methods developed by OR and because the use of mathematical methods in real management is facing difficulties. The relationship of MS with information systems (IS) and organisation research (Org) is analysed in regard to the competition of MS with OR. The analysis reveals the intermediate character of MS; that is, MS is less prone to mathematical methods and is more inclined towards IS and Org than OR is. This revised version was published online in June 2006 with corrections to the Cover Date.     

STRUCTURE FORMATION OF COATED FILMS WITH DISPERSED PIGMENTS DURING DRYING

In the drying of coated films with dispersed pigments, such as floppy disks, the structure of the film is formed during the drying process and depends on the drying condition. It is important to understand the structure formation during drying for the design of the dryer and die better quality of the product. We measured die drying characteristics of the film and determined the structure of dried film experimentally. A qualitative model for the structure formation during drying of the coated film is suggested.     

Pixel-selected ray tracing

An acceleration method based on an idea that T. Whitted (Commun. ACM, vol.23, no.6 pp.343-349, June 1980) presented on ray tracing is discussed. He proposed making antialiased images by hierarchical adaptive oversampling. The present authors use hierarchical adaptive undersampling to reduce the number of pixels whose intensity must be calculated by ray tracing. To implement pixel-selected ray tracing (PSRT), homogeneous regions in images must first be found. Generally, adaptive undersampling can result in some image-quality defects, because small objects and parts of thin or wedge-shaped objects may disappear when they are located between the initially sampled pixels. PSRT has an improved algorithm that uses pixels with the correct object information from among the sampled pixels to find pixels with erroneous color and correct them. Moreover, PRST uses ray-object intersection trees for precise classification of the homogeneity of regions and for fast intensity calculation in homogeneous regions. Experimental results are presented. They show that PSRT is two to nine times faster than standard ray tracing     

Growth of Al2O3 whiskers by vapour-phase reactions

Needle-like or wool-like Al₂O₃ whiskers can be grown on a substrate by the hydrolysis of aluminium fluoride vapour. Effects of the growth conditions on the morphology of the crystals and growth processes of the whisker were investigated, and the optimum growth condition of whiskers was examined. Adequate vapour pressure conditions of the reactant gases for the growth of the wool-like whisker were found to be . Aluminium oxyfluoride was assumed to be the most probable intermediate species for the growth of Al₂O₃ whiskers. A variety of crystal morphologies are also shown and described with respect to the experimental conditions.     

Effect of Composition on the Oxygen Tracer Diffusion in Transparent Yttrium Aluminium Garnet (YAG) Ceramics

The grain boundary structure and oxygen tracer diffusion in transparent yttrium aluminum garnet (YAG) ceramics varying from 2% excess of Y₂O₃ to 0.5% excess of Al₂O₃ were studied. The characterization of the specimens is as follows: (i) For the Y₂O₃-excess specimen, a second phase (yttrium aluminum perovskite: YAP) containing silicon in the grain boundary was found, (ii) For the Al₂O₃-excess specimen, both aluminum-rich particles (alumina) and a silicon-rich segregant layer were observed in the grain boundary. The volume diffusion of the oxygen tracer is little influenced by the excess composition. In contrast, the grain boundary diffusion of the oxygen tracer is suppressed in the Y₂O₃-excess specimens, compared to Al₂O₃-excess specimens. These differences are thought to result from the chemical reaction between the second phase and the intergranular liquid phase during the sintering.     

Formation and Crystallization of Yttrium Aluminosilicate Glasses Containing Calcium Oxide

Formation of yttrium aluminosilicate glasses containing calcium oxide from batches melted at 1550°C was investigated. Densities and thermal expansion coeflcients were measured for some glasses. In a specific compositional region, crystals with a needlelike habit were observed in the glass matrix. A crystal in the form of a tubular hexagonal prism was identified as Ca₄Y₆0(Si0₄)₆.     

Production of dihomo-γ-linolenic acid byMortierella alpina 1S-4

The mycelial dihomo-γ-linolenic acid content of an arachidonic acid-producing fungus,Mortierella alpina 1S-4, was found to increase, with an accompanying marked decrease in its arachidonic acid content, on cultivation with sesame oil. The resultant mycelia were found to be a rich source of dihomo-γ-linolenic acid. This unique phenomenon was suggested to be due to specific repression of the conversion of dihomo-γ-linolenic acid to arachidonic acid by the oil. After fractionation of the oil with acetone into oil and non-oil fractions, it was found that the effective factor(s) was present in the non-oil fraction. In a study on optimization of the culture conditions for the production of dihomo-γ-linolenic acid byM. alpina 1S-4, a medium containing glucose, yeast extract and the non-oil fraction was found to be suitable for the production. Under the optimal conditions in a 50-1 fermentor, the fungus produced 107 mg of dihomo-γ-linolenic acid/g dry mycelia (2.17 g/l of culture broth). This value accounted for 23.1% of the total fatty acids in the lipids extracted from the mycelia. The mycelia were also rich in arachidonic acid (53.5 mg/g dry mycelia, 11.2%). Other major fatty acids in the lipids were palmitic acid (24.1%), stearic acid (7.0), oleic acid (20.1), linoleic acid (6.6) and γ-linolenic acid (4.1). On leave from Suntory Ltd.     

Synthesis and electrode performance of layered nickel dioxide containing alkaline ions

Several polymorphs of layered nickel dioxide were prepared by using the chemical insertion of alkaline ions into Li_0.10NiO₂. We used aqueous AOH (A = Li, Na, K) solutions as reducing agents. Sodium and potassium insertion resulted in hydrated layered compounds that can be classified as γ-NiOOH with high crystallinity, while lithium insertion occurred without hydration. We discuss the coordination environment around the A⁺ ions for these inserted compounds. The thermal behavior, analyzed using high temperature (HT) X-ray diffraction (XRD) and thermogravimetric (TG) measurements, indicated that heating the hydrate at 150 °C yielded its dehydrate. The electrode performance of the nickelate was studied in lithium cells. We discuss the effect of interlayer water on cell rechargeability and the similarity between these nickelate and hydrated manganese dioxide (birnessite).