Propagation characteristics of the magnetostatic surface wave inthe YBCO-YIG film-layered structure

Propagation characteristics of the magnetostatic surface wave (MSSW) in a YBa₂Cu₃O_7-x (YBCO)-yttrium iron garnet (YIG) multilayered structure are investigated. Effects of the superconductor on the MSSW are discussed with regard to the dispersion characteristics of both the phase and attenuation constants as a function of the air gap, between YIG and YBCO, taking into consideration the magnetic line-width of the YIG film. It was found that the nonreciprocity of MSSW is enhanced significantly by the superconductivity and depends on the magnetic line-width of the YIG film. To examine the effect of a YBCO on the MSSW propagation, experiments are carried out using a commercially available YIG film. Magnetic losses at low temperature are briefly discussed with experimentally observed nonreciprocity     

Light-controlled microstrip line coupler

Journal of Infrared, Millimeter, and Terahertz Waves - We have analyzed coupling properties of the coupled microstrip lines whose substrate contain electron-hole plasma by means of the spectral...     

Network polyester films from glycerol and dicarboxylic acids

This paper presents information on the preparation of the network polyester films from glycerol (Y_g) and aromatic dicarboxylic acids of phthalic anhydride (P), dimethyl isophthalate (I) and dimethyl terephthalate (T), as well as aliphatic dicarboxylic acids of adipic, sebacic, 1, 10-decanedicarboxylic and 1, 12-dodecanedicarboxylic acids, and their properties. Y_g and dicarboxylic acid were polycondensed immediately before the gelation started. The prepolymers obtained were cast from DMF solution and successively post-polymerized at various temperatures and times to form networks. The resultant films were transparent, flexible and insoluble in organic solvents. Heat distortion temperature (T_h) measured by a penetration mode of thermomechanical analysis increased with increasing post-polymerization temperature and time, and then leveled out. T_h values corresponded well to the glass transition temperature (T_g) measured by differential thermal analysis (DTA). T_h was 152°C, 162°C and 197°C for Y_gP, Y_gI and Y_g T post-polymerized at 270°C for 6 h, respectively. T_h values of network films made from aliphatic dicarboxylic acids could not be observed until complete probe penetration occurs, as a result of thermal decomposition because the T_g is lower than room temperature. The degree of reaction estimated from the IR absorbance of hydroxyl and methylene groups was in the range of 60–80%. Two diffraction peaks appeared in the wide-angle X-ray scattering pattern, suggesting some ordered structure owing to the regular networks. Density decreased with increasing post-polymerization time and temperature, in the order Y_gP > Y_gI > Y_gT. Network films made from aliphatic dicarboxylic acids had much lower tensile strength and Young's modulus, and greater elongation, than those made from dicarboxylic acids, as a result of the T_g being below room temperature.     

Improvement of performance of disk MHD generator with argon by introduction of swirl

An experimental study of performance of the disk MHD generator with argon was carried out using a shock‐tube driven facility. An inlet swirl was introduced in the MHD channel in order to improve the enthalpy extraction and the isentropic efficiency. The experimental results were compared with those of the disk MHD generator without the inlet swirl. A high enthalpy extraction of 25.7% was obtained and the highest isentropic efficiency for argon was achieved at the same time in the present experiment. The measured static pressure in the MHD channel was kept lower than that without the inlet swirl. This has suggested that the introduction of the inlet swirl reduces the retarding force for the flow and that the increase of the enthalpy extraction is ascribed to the increase of the flow velocity and of the electrical efficiency. Furthermore, the flow without shock wave was observed at low seed fractions and low load resistances. At the same time, it was found for the first time that when there was no shock wave, the isentropic efficiency became higher than that with the shock wave. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(1): 18–25, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10045     

Computer simulation study of short-range order hardening

Computer simulation is used to analyze the short-range order hardening (SROH) effect in Cu-25 at. pct Au. It is confirmed that the subsequent dislocations randomize the state of order of a system. O. SASAKI, formerly with Dai Nippon Printing Company, Tokyo 162 K. WATANABE, formerly with the Department of Metallurgical Engineering, Hokkaido University     

Analysis of Anal Secretions from Phlaeothripine Thrips

The anal secretions of 16 phlaeothripine thrips species (Thysanoptera: Phlaeothripidae) were studied, including a reinvestigation of three species previously reported. A total of 37 components were detected, including hydrocarbons, acetates, terpenes, carboxylic acids, a quinone, an aromatic compound, and a pyranone compound. The secretions of all species were composed of some of these components, with Xylaplothrips inquilinus possessing as many as 11 components. Of these components, (Z)-9-octadecene, (Z)-9-nonadecene, nonadecadiene, octanoic acid, decanoic acid, geranial, neral, alpha-pinene, beta-pinene, caryophyllene, 2-hydroxy-6-methylbenzaldehyde, and two unidentified monoterpenes [UK-I (M+136) and UK-II (M+168)] were detected for the first time. The chemicals were species-specific; four Liothrips species and three Holothrips species could be distinguished from each other and their congeners by the GC profiles of the ether extracts of their anal secretions. The anal secretions of gall-inducing thrips commonly contained terpenes. of which citral (a mixture of geranial and neral) and beta-acaridial repelled ants or had antifungal activity. The findings suggest that these terpenes play a defensive role and prevent galls from fungal infestation. 3-Butanoyl-4-hydroxy-6-methyl-2H-pyran-2-one, found from three Holothrips spp., caused paralysis in ants. Chemical analysis of anal secretion components is a useful method for the classification of tubuliferan species that are difficult to distinguish on the basis of morphological characters.     

Positron lifetime calculations on vacancy clusters and dislocations in Ni and Fe

Positron lifetime calculations have been performed on vacancy clusters (stacking fault tetrahedra (SFT), vacancy loops), such clusters on dislocation line, interstitial clusters, such clusters on a dislocation line and dislocation line itself in order to investigate the so-called intermediate lifetimes observed in the experiments, namely, positron lifetimes between that at a matrix and that at a single vacancy. Before lifetime calculations, various defects were constructed in the model lattices and were relaxed completely to obtain the stable atomic structure by using N-body potentials. Then positron lifetime calculation was carried out for each defect. It was shown that positron lifetime for a SFT in Ni dependes on its size and becomes smaller with increasing the size. The positron wave function is mainly localized at the corner of a SFT, which gives rather lifetime, e.g., 130 ps for V₂₈, but when the cluster size is small, e.g., less than 10 vacancies, it gives a rather longer lifetime, e.g., 177 ps for V₆ because of the wave function localized at the inner space of a cluster. These behaviours are consistent with the experimental results. It was also found that the positron lifetime on a dislocation line and that at a jog are short (113 and 119 ps, respectively for Ni, 117 and 117 ps, respectively for Fe), close to the lifetime at matrix (110 ps for both Ni and Fe) and in these cases trapping potentials for a positron are shallow both for Ni and Fe.