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71.
Transparent hexagonal BN films were deposited onto copper substrates from the reactant gas BCl3-NH3-H2 at temperatures in the range 250–700°C. The lowest deposition temperature of the films was about 250°C. The films deposited at temperatures below 450°C were unstable in moist atmosphere and devitrified; a 20%–30% decrease in weight was observed when these films were heated above 600°C in an argon atmosphere. In contrast, the films deposited at temperatures above 600°C were very stable, decreased in weight by 1%–2% on heating and were stable in air at temperatures below 750°C. 相似文献
72.
In this paper, the authors propose a method that incorporates mechanisms for handling ambiguity in speech and the ability of humans to create associations, and for formulating conversations based on rule base knowledge and common knowledge. Go beyond the level that can be achieved, using only conventional natural language processing and vast repositories of sample patterns. In this paper, the authors propose a method for computer conversation sentences generated using newspaper headlines as an example of how the common knowledge and associative ability are applied. 相似文献
73.
On the heat removal characteristics and the analytical model of a thermal energy storage capsule using gelled Glauber's salt as the PCM 总被引:1,自引:0,他引:1
Akio Saito Seiji Okawa Tadafumi Shintani Ryuichiro Iwamoto 《International Journal of Heat and Mass Transfer》2001,44(24):4693-4701
An analytical and experimental investigation was performed on a heat removal process of the thermal energy storage (TES) capsule, using gelled Glauber's salt. Transient heat flux at the capsule wall was measured for various cooling conditions. In cases where the initial temperature was lower than the saturation temperature of the phase change material (PCM), numerical analyses were performed, approximating the process by a relaxation phenomenon where crystals grew around crystal nuclei. The results of the numerical solution agreed very well with the experimental results. 相似文献
74.
We discuss the general theoretical arguments advanced earlier for the T=0 global phase diagram of antiferromagnetic Kondo lattice systems, distinguishing between the established and the conjectured. In addition to the well-known phase of a paramagnetic metal with a “large” Fermi surface (PL), there is also an antiferromagnetic phase with a “small” Fermi surface (AFS). We provide the details of the derivation of a quantum non-linear sigma-model (QNLσM) representation of the Kondo lattice Hamiltonian, which leads to an effective field theory containing both low-energy fermions in the vicinity of a Fermi surface and low-energy bosons near zero momentum. An asymptotically exact analysis of this effective field theory is made possible through the development of a renormalization group procedure for mixed fermion-boson systems. Considerations on how to connect the AFS and PL phases lead to a global phase diagram, which not only puts into perspective the theory of local quantum criticality for antiferromagnetic heavy fermion metals, but also provides the basis to understand the surprising recent experiments in chemically-doped as well as pressurized YbRh2Si2. We point out that the AFS phase still occurs for the case of an equal number of spin-1/2 local moments and conduction electrons. This observation raises the prospect for a global phase diagram of heavy fermion systems in the Kondo-insulator regime. Finally, we discuss the connection between the Kondo breakdown physics discussed here for the Kondo lattice systems and the non-Fermi liquid behavior recently studied from a holographic perspective. 相似文献
75.
Surface properties of carbon micro-coils oxidized by a low concentration of oxygen gas 总被引:1,自引:0,他引:1
Vapor-grown carbon micro-coils were oxidized under a low O2 flow-rate for introducing oxygen-containing functional groups on the surface. The surface characteristics were then examined. The O1s/C1s intensity ratios of the XPS spectra measured on the surface increased on using the oxidation treatment. The maximum O1s/C1s ratio of 11.4 at.% was obtained under the following conditions: (a) the flow-rate of the mixed gas of O2+Ar (O2/Ar=1/10) was 82.5 sccm; (b) the oxidation temperature was 600°C; and (c) the treatment time was 30 min. The maximum O1s/C1s ratio is about 3.5 times that of the source carbon coils. The specific surface area significantly increased due to the oxidation treatment and attained a maximum value of 1050 m2 g−1, which is about 10 times that of the source carbon coils. As the specific surface area increased, the surface morphology of the carbon coils became more complicated on a nanometer scale. 相似文献
76.
Two robust disturbance-rejection problems with state feedback and with incomplete-state feedback for linear ω-periodic discrete-time systems are studied in the framework of the so-called geometric approach. Also, some necessary conditions and/or sufficient conditions for the problems to be solvable are presented 相似文献
77.
The carbon black/alumina gel composites were prepared by sol-gel reaction of aluminum isopropoxide in the presence of polymer-grafted carbon black. The electric resistance of the alumina gel composite from polymer-grafted carbon black was very sensitive to vapor of good solvent for grafted polymer on carbon black: the electric resistance of the alumina gel composite suddenly decreased in solvent vapor and returned to initial resistance when it was transferred into dry air. The effect of surface area and particle size of carbon black on the responsiveness was also investigated. In addition, the electric resistance of the alumina gel composite was found to respond to water and methanol in n-hexane and diethyl ether. 相似文献
78.
The solubility of fullerene C60 in toluene was measured at temperatures between 278.2 and 308.2 K and pressures up to 340 MPa, and also at temperatures between 258.2 and 298.2 K under atmospheric pressure. The solubility increased with increasing pressure, and then decreased with a sharp maximum, suggesting a transition between solid phases. A thermodynamic analysis of the solubility supported the proposal of Korobov, et al. that the two solids correspond to C60 (fcc) and C60 · 2 (toluene) solvate. The solubility enhancement of C60 by pressure in a low-pressure region is an unusual phenomenon when compared with the decrease in solubility of nonpolar molecular solids generally observed with rises in pressure. 相似文献
79.
Seiji Motojima Noriyuki Iwamori Tatsuhiko Hattori 《Journal of Materials Science》1986,21(11):3836-3842
Si3N4 layers were obtained on a quartz substrate from a gas mixture of Si2Cl6, NH3 and H2 under a reduced pressure in a temperature range of 800 to 1300‡ C. Amorphous Si3N4 layers that were dense and adherent to the substrate were obtained in a temperature range of 800 to 1100‡ C. On the other
hand,α-Si3N4 layers were obtained at 1200‡ C and a source-gas ratio (N/Si) of 1.33 to 1.77. The lowest deposition temperature of amorphous
Si3N4 was considered to be about 700‡ C. The microhardness of amorphous Si3N4 obtained in a temperature range of 800 to 1100‡ C was 2400 to 2600 kg mm−2 (load: 50 g), and that ofα-Si3N4 obtained at 1200‡ C was 3400 kg mm−2. Chlorine contents in the Si3N4 layer decreased with increasing deposition temperature and source-gas ratio (N/Si), and with decreasing total pressure. 相似文献
80.
Microstructure Development and Dielectric Properties of Potassium Strontium Niobate Ceramics 总被引:1,自引:0,他引:1
Toshio Kimura Seiji Miyamoto Takashi Yamaguchi 《Journal of the American Ceramic Society》1990,73(1):127-130
Sintering of a KSr2 Nb5 O15 powder compact at 1350°C resulted in a duplex structure. Prefiring of the compact between 1200° and 1300°C inhibited the abnormal grain growth responsible for the duplex structure. The Curie temperature and dielectric constant were dependent on the microstructure. 相似文献