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51.
Kawahira H. Kubo Y. Yokoyama T. Ogata J. 《Industry Applications, IEEE Transactions on》1990,26(2):359-365
The effect of an electric field on boiling refrigerant R-11 was investigated experimentally. The test section consisted of a flat plate and a single tube with several rows of electrode wire. The influence of refrigerant oil, the surface roughness of the test tube, and polarity of an applied voltage on the heat transfer performance were studied. The following results were obtained: as the applied voltage increased, the number of boiling bubbles decreased but the heat transfer coefficient increased; no deterioration of heat by the oil contamination occurred; and the polarity of the applied voltage affected the boiling heat transfer 相似文献
52.
A new MBE growth method for the fabrication of a high-quality double hetero-epitaxial Si/γ-Al2O3/Si structure was recently developed. In the present work, characteristics of NMOSFETs fabricated on the Si/γ-Al2O3/Si structure were investigated, and compared with those on a Si/MgAl2O4/Si structure. A γ-Al2O3 layer was created from a MgAl2O4 layer by reaction with Si beams as follows: MgAl2O4 + Si → γ-Al2O3 + SiO ↑ + Mg ↑. The MBE growth of Si on the effectively restructured γ-Al2O3 layer was then performed at a substrate temperature of 700° C, 150° C lower than for the MBE growth of Si on a MgAl2O4/Si substrate. The electron field effect mobility and leakage current between source and drain for the NMOSFETs fabricated
on Si/γ-Al2O3/Si structures were 660 cm2/V · s and 2.8 pA/μm respectively, and exhibited a higher level of performance than those on a Si/MgAl2O4/Si structure. In the Si/MgAl2O4/Si, SIMS measurements confirmed that autodoped Al and Mg atoms near the interface between the Si epi-layer and MgAl2O4/Si substrate diffused anomalously and accumulated at the surface during device fabrication processes. These autodoped Al
and Mg atoms acted as ionized impurities during test operation. Suppression of autodoping from insulator layers during the
MBE growth of Si was thus deemed essential to the improvement of NMOSFET characteristics. In the Si/γ-Al2O3/Si structure, autodoped atoms were scarcely detectable. It was therefore concluded that the Si/γ-Al2O3/Si structure under study was very promising for SOI device applications. 相似文献
53.
The dehydrofluorination of poly(vinylidene fluoride) (PVDF) powder and films was studied using several kinds of base solution. Especially the reactivity of 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) in ethanol, KOH in 2-propanol and aqueous NaOH solution with tetrabutylammonium bromide was investigated by the change in infrared (IR) and ultraviolet-visible (UV-VI) absorptions of PVDF films. The elimination reactions by DBU or KOH were considered to be accompanied by substitution reaction. The electrical conductivity of dehydrofluorinated PVDF films increased markedly by doping with iodine, and the activation energies of conduction were found to be between 0.4 and 0.5 eV. When a drawn PVDF film was dehydrofluorinated and doped with iodine, anisotropy in conductivity was observed. 相似文献
54.
55.
Taiki Shimbo 《Soils and Foundations》2018,58(2):481-490
In this paper, we present an implicit stress-calculation algorithm for a multidimensional constitutive law using a one-dimensional skeleton curve and a hysteresis curve. To consider the hysteretic behavior of soils, one-dimension skeleton curves (e.g., the Hardin–Drnevich model, Ramberg–Osgood (RO) model, and general hyperbolic equation (GHE) model) are widely used. In a multidimensional analysis, there are several methods for extending a constitutive law using a skeleton curve into multiple dimensions. However, because these methods are suitable for an explicit integration stress-calculation scheme, a calculated stress does not satisfy the function of skeleton curve when a large incremental strain is imposed in one step. In this paper, to resolve this problem, a nonlinear stress–strain relation using a skeleton curve and an implicit stress-calculation algorithm is presented. In addition, we show an example of an application of the GHE/RO model to the proposed algorithm. 相似文献
56.
When the motor speed is reduced by using a regenerative brake, the mechanical energy of rotation is converted to electrical energy. When the regenerative torque is large, the corresponding current increases so that the copper loss also becomes large. On the other hand, the damping effect of rotation increases with time when the regenerative torque is small. In order to use this limited energy effectively, the optimal regenerative torque should be ascertained in order to maximize the regeneration of electrical energy. This paper proposes a methodology, based on the variational method, for the design of regenerative torque for an induction motor in order to maximize the regenerative electric energy. Similarly, the optimal torque for acceleration is derived in order to minimize the driving energy. Finally, an efficient motor drive system with the proposed optimal torque and a power storage system stabilizing the DC link voltage will be proposed. The effectiveness of the proposed methods is illustrated by simulations and experiments. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(1): 41–50, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.21010 相似文献
57.
Thermosensitive 4VP‐NIPAAm‐4G copolymer beads containing pyridyl groups were first prepared by suspension copolymerization of 4‐vinylpyridine (4VP), N‐isopropylacrylamide(NIPAAm), and tetraethylene glycol dimethacrylate (4G; crosslinking reagent) in a saturated Na2SO4 aqueous solution in the presence of surfactant and MgCO3 as dispersants. Then the copolymer beads containing pyridinium groups were obtained by the quaternization of the copolymer beads with various alkyl iodides (CH3I, C4H9I, C8H17I) in N,N‐dimethylformamide. The 4VP‐NIPAAm‐4G (15 : 97 : 3) copolymer bead and the 4VP‐NIPAAm‐4G copolymer beads quaternized with butyl iodide exhibited high thermosensitivity in water, although the 4VP‐NIPAAm‐4G copolymer beads quaternized with methyl iodide or octyl iodide hardly exhibited thermosensitivity. All the quaternized copolymer beads exhibited antibacterial activity against Escherichia coli (E. coli), although the 4VP‐NIPAAm‐4G copolymer bead did not. In particular, the copolymer bead quaternized with butyl iodide exhibited the highest antibacterial activity against E. coli at 30°C. It was also found that the antibacterial activity of the quaternized 4VP‐NIPAAm‐4G copolymer beads was greatly affected by not only chain length of alkyl groups in alkyl iodides, with which the 4VP‐NIPAAm‐4G copolymer beads were quaternized, but also by temperature of the solutions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
58.
M Nakamura T Nagamine K Ogata K Tajima RI Aminov Y Benno 《Canadian Metallurgical Quarterly》1999,38(2):107-112
The degradation kinetics of five glutamine dipeptides in aqueous solution, i.e. glycyl-L-glutamine (Gly-Gln), L-alanyl-L-glutamine (Ala-Gln), L-valyl-L-glutamine (Val-Gln), L-leucyl-L-glutamine (Leu-Gln) and L-isoleucyl-L-glutamine (Ile-Gln), were studied. Stability tests were performed using a stability-indicating high-performance liquid chromatographic assay. Two different Ala-Gln degradation routes, i.e. the cleavage of a peptide bond and the deamination of an amide group, were observed. The degradation was adequately described by pseudo-first-order kinetics. The maximum stability of Ala-Gln was obtained at an approximate pH of 6.0. The pH-rate profile described by specific acid-base catalysis and hydrolysis by water molecules agreed with the experimental results. The activation energy of Ala-Gln at pH 6.0 was determined to be 27. 1kcal mol-1, and the shelf-life (90% remaining) at 25 and 40 degrees C was predicted to be 5.3 years and 7.1 months, respectively. The rate constants of the glutamine dipeptides were influenced by the N-terminal amino acid residue and decreased in the order: Gly-Gln, Ala-Gln, Leu-Gln, Val-Gln and Ile-Gln. 相似文献
59.
Haruhiko Morito Tomoyuki Ide Taiki Karahashi Hironori Orikasa Takahiro Yamada Hisanori Yamane 《Journal of the American Ceramic Society》2009,92(11):2578-2582
A bulk layer of aluminum nitride (AlN) polycrystals was synthesized on a boron nitride crucible surface by heating Al chunks with 5 mol% of bismuth at 1273 K for 3 h under NH3 gas flow. The fragments of the layer were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The platelet grains of AlN with a size of 0.1–1.0 μm and having preferred orientation of the c -axis perpendicular to the layer were formed at the crucible side. Nanotubes 6–15 μm long and about 20–100 nm thick grew on the gas phase side of the layer. 相似文献
60.
Takagi S Frukhtbeyn S Chow LC Sugawara A Fujikawa K Ogata H Hayashi M Ogiso B 《Journal of research of the National Institute of Standards and Technology》2010,115(4):267-276
This study reports for the first time in vitro and in vivo properties of fluorapatite (FA)-forming calcium phosphate cements (CPCs). The experimental cements contained from (0 to 3.1) mass % of F, corresponding to presence of FA at levels of approximately (0 to 87) mass %. The crystallinity of the apatitic cement product increased greatly with the FA content. When implanted subcutaneously in rats, the in vivo resorption rate decreased significantly with increasing FA content. The cement with the highest FA content was not resorbed in soft tissue, making it the first known biocompatible and bioinert CPC. These bioinert CPCs might be useful for applications where slow or no resorption of the implant is required to achieve the desired clinical outcome. 相似文献