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31.
Kazuhiro Kajikawa Katsuyuki Kaiho Mitsuyoshi Yamamoto Hiroshi Fuji Nobuyuki Sadakata Takashi Saito Osamu Kohno 《Electrical Engineering in Japan》1996,117(5):34-43
Recently, multifilamentary superconducting wires with very low ac losses have been produced and practical applications will now be considered. To realize actualsize power machines and apparatuses, it is necessary to develop 1 - 10 kA ac conductors. However, the critical currents of multifilamentary wires at 1 T are several tens of A, and therefore it is necessary to use multistrand conductors consisting of several tens or several hundreds of strands. Such conductors sometimes show ac current degradation because of such factors as (1) nonuniform current distribution, (2) wire motion, (3) temperature increase, (4) longitudinal magnetic field effect, etc. Formerly, a coreless transformer was considered unpractical because of its large exciting current. However, Yamamoto and others proposed that a coreless superconducting transformer could be used as a stepdown autotransformer at the receiving side, utilizing its large exciting current as the reactive power source to cancel the charging current of an underground transmission line or UHV line, and therefore the shunt reactors could be eliminated. In this paper, development of ac-superconducting conductors aimed at prevention of current degradation are discussed, as well as quench test results of two small coils made with these conductors. In these conductors, low ac low strands with ultrafine NbTi filaments are twisted around a central bundle of stainless steel wires. One of the coils has been designed as a model coreless autotransformer, and its test result is also described. 相似文献
32.
Kazuhiro Saito Mitsuru Yoneyama Mitsuyoshi Saito Keiichi Ikegami Michio Sugi
Takayoshi Nakamura
Mutsuyoshi Matsumoto Yasujiro Kawabata 《Thin solid films》1988,160(1-2):133-137Photoelectric cells based on Langmuir-Blodgett (LB) films were fabricated using dye monolayers as photoconductors and N-docosylpyridinium-di(tetracyanoquinodimethane) (PT) monolayers as one of the electrode materials. It is found that PT films can be used as a wiring material instead of large work function metals such as silver or Ni-Cr. However, in comparison with the photoelectric cells using the conventional metals, a few different properties were observed for those wired with PT. These differences are assignable to the difference between the LB film-metal and the LB film-LB film contacts. 相似文献
33.
34.
Rheological properties of metallocene‐catalyzed isotactic polypropylenes (MET‐PP) were evaluated in comparison with those of Ziegler–Natta‐catalyzed isotactic polypropylenes (ZN‐PP) and MET‐PP was generally characterized in a rheological aspect. Based on the characterization, various flow processibilities and their effect on the higher order structure and product properties of the processed article were estimated. The capillary flow properties at various temperatures, elongational flow properties, and dynamic viscoelasticities of MET‐PPs and ZN‐PPs with various melt flow indexes (MFIs) were measured. Furthermore, as an example of application of rheological analysis, the selection of proper raw resin and processing conditions in the sheet‐extrusion of MET‐PP was studied. MET‐PP shows the following rheological features due mainly to the narrow molecular weight distribution in comparison with ZN‐PP with equivalent MFI to that of MET‐PP: while the viscosities at low shear rates are lower, those at high shear rates are higher. Although there is little difference in the loss modulus G″ (viscosity), the storage modulus G′ (elasticity) is very (about one decade) lower. The die swell is much smaller. The entrance pressure loss and end correction coefficient are lower. The critical shear rate at which a melt fracture begins to occur is lower. The melt tension, elongational viscosity, and melt flow index ratio are lower. The flow activation energy is slightly lower. The zero‐shear viscosity obeys the 3.4th‐power law independent of catalyst. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2157–2170, 2002 相似文献
35.
Polypropylene (PP)‐type resins with narrow molecular weight distribution, such as PP‐type thermoplastic elastomer PER and controlled‐rheology PP (CRPP) made by peroxide degradation of high molecular weight PP, have a problem of easy generation of skin roughness at extrusion. To examine the present state, the occurrence of skin roughness in PER and CRPP at extrusion was investigated with a capillary rheometer in a shear rate range of 12–6100 s?1 and a temperature range of 180–280°C. A homo‐PP (HPP) and a block‐PP (BPP) with usual molecular weight distributions were used for comparison. HPP and BPP with usual molecular weight distributions show smooth extrudates at low shear rates and abruptly generate severe skin roughness “elastic failure” originating at the die entrance at a higher shear rate. PER and CRPP with narrow molecular weight distributions easily generate “sharkskin” melt fracture originating at the die exit, from a shear rate nearly one decade lower than rates of elastic failure of HPP and BPP. The sharkskin becomes more severe, with increasing shear rate, and attains to the elastic failure. The critical shear rate at which sharkskin occurs increases with increasing extrusion temperature. The critical shear rate is about 20 s?1 at 180°C and about 120 s?1 at 280°C, which is in the range encountered by the molten resin at extrusion processing. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2111–2119, 2002 相似文献
36.
Mitsuyoshi Nomura Yongbo Wu Tsunemoto Kuriyagawa 《Journal of Mechanical Science and Technology》2007,21(10):1605-1611
In internal grinding of small holes, it is hard to realize high accuracy truing and dressing for the grinding wheel when a
conventional truing/dressing method using single diamond dresser or rotary cup wheel is employed. Because of the cantilever
support condition of the spindle shaft the stiffness of shaft is reduced. Thus the truing force leads the shaft to a significant
deformation during truing/dressing. In this study, for improving the truing and dressing accuracy, a new truing/dressing method
was proposed, in which the grinding wheel is ultrasonically vibrated along its axis during truing/dressing with a GC rotary
cup wheel. A series of experiments were carried out to investigate the effects of the wheel ultrasonication on the truing
force reduction, the truing accuracy improvement and the wheel surface condition. In addition, the grinding force and work
surface roughness experimentally obtained by using the wheels trued with or without ultrasonication were compared. The experimental
results indicated that applying ultrasonic vibration to the wheel decreases the normal and tangential grinding forces by more
than 20% and 24%, respectively, and the surface roughness by as much as 18%. 相似文献
37.
Akihiko Kosugi Akihiko Kondo Mitsuyoshi Ueda Yoshinori Murata Pilanee Vaithanomsat Warunee Thanapase Takamitsu Arai Yutaka Mori 《Renewable Energy》2009,34(5):1354-1358
Cassava (Manihot esculenta Crantz) pulp, produced in large amounts as a by-product of starch manufacturing, is a major biomass resource in Southeast Asian countries. It contains abundant starch (approximately 60%) and cellulose fiber (approximately 20%). To effectively utilize the cassava pulp, an attempt was made to convert its components to ethanol using a sake-brewing yeast displaying glucoamylase on the cell surface. Saccharomyces cerevisiae Kyokai no. 7 (strain K7) displaying Rhizopus oryzae glucoamylase, designated strain K7G, was constructed using the C-terminal-half region of α-agglutinin. A sample of cassava pulp was pretreated with a hydrothermal reaction (140 °C for 1 h), followed by treatment with a Trichoderma reesei cellulase to hydrolyze the cellulose in the sample. The K7G strain fermented starch and glucose in pretreated samples without addition of amylolytic enzymes, and produced ethanol in 91% and 80% of theoretical yield from 5% and 10% cassava pulp, respectively. 相似文献
38.
Naoko?Yuno-OhtaEmail author Katsuo?Murata Mitsuyoshi?Miyahara Hiroyuki?Ohta 《Journal of the American Oil Chemists' Society》2004,81(3):225-230
In this study, we found that transparent gels of β-lactoglobulin (β-LG) were formed by adding different concentrations of
sodium caprate to protein solutions at ambient temperature. We investigated changes in the dynamic viscoelasticity of the
mixture with time at 25°C and found that more than 12% β-LG induced the formation of a viscoelastic gel with a suitable amount
of sodium caprate (for example, 12% β-LG and 3.6% sodium caprate). Furthermore, we analyzed the changes in the secondary structure
of proteins during the gelation step by FHR spectroscopy. Dissociation of the β-LG dimer was first observed just after mixing
with sodium caprate. Furthermore, in the β-LG protein in which the original contents were predominantly β-sheets, intermolecular
β-sheets attributable to aggregation increased with a decrease in the content of intramolecular β-sheets. Sodium caprate-induced
gel was heated at 80°C for 30 min after the gel was formed, and a large increase in the intermolecular β-sheet bands was observed
by heat treatment. These results suggest that the formation of sodium caprate-induced gels of β-LG was accompanied by less
marked changes in the protein conformation than those in heat-induced gels. 相似文献
39.
In this study, several methods to convert rain rate data for various time intervals to one‐minute rates are compared. High‐resolution tipping bucket precipitation records for seven locations in a tropical region are analyzed and compared using these conversion models. The Segal, Chebil, and Burgueno methods give the smallest average errors below 10% at different integration times. 相似文献
40.
Mitsuyoshi Fujiyama 《应用聚合物科学杂志》1997,63(8):1015-1027
A homoisotactic polypropylene (PP) was melt blended with 0–30 wt % of three kinds of polystyrene (PS) with melt flow indexes lower than, similar to, and higher than that of PP. The blends were injection molded at cylinder temperatures of 200–280°C, and the structure and properties of the injection moldings were studied. With PS blending, although the PP molding whitened, no surface defect such as layer peeling and pearl-like appearance occurred. The rigidity and dimensional accuracy of the molding improved without much deterioration in impact strength and heat resistance. At the same time the fluidity also improved. The injection moldings of PP/PS blends did not show clear skin/core structure under a polarizing microscope. The degrees of crystallinity and crystalline c-axis orientation decreased with PS blending. PS particles were the smallest when the ratio of the viscosity of the PS to that of PP at molding shear rate was slightly lower than unity. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1015–1027, 1997 相似文献