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31.
Hiroshi Watanabe Mitsutake Motozawa Ken Suto Jun-Ichi Nishizawa 《Journal of Electronic Materials》1998,27(8):979-984
Photocapacitance (PHCAP) and photoluminescence (PL) measurements were applied to unintentionally doped p-type Al0.38Ga0.62As grown by liquid phase epitaxy using the temperature difference method under controlled vapor pressure. PHCAP spectra revealed
three dominant deep levels at Ev+0.9, Ev + 1.45, and Ev+1.96 eV, and a deep level at Ev+0.9−1.5 eV which was not neutralized by forward bias injection. These level densities increase with increasing arsenic vapor
pressure and net shallow acceptor density. Furthermore, PL spectra reveal a deep level at 1.6–1.7 eV. The PL intensity of
this deep level increases with increasing arsenic vapor pressure. These deep levels are thought to be associated with excess
As. 相似文献
32.
To evaluate the intraparticle diffusion coefficient, De, of a component in a liquid, it was assumed that the pore structure of a porous catalyst was a space between an assembly of fine particles. This structure has been found for the metal oxide catalysts. The diffusivity ratio, δ (= De/D), was geometrically estimated in the direction normal to the representative plane (100), (110) or (111) of cubic closed, body centered cubic, simple cubic, or diamond packing of spherical elementary particles. The value δ was found to approximate the porosity ?. Larger pore constrictions gave smaller δ/? values. Reaction rates were measured for the hydrogenation of nitrobenzene in ethanol. The efficiency of this evaluation of De was supported by the agreement of the experimental effectiveness factor with the theoretical factor. 相似文献
33.
Jun-Ichi Kawabata Midori Yumiyama Yoneshiro Tazaki Senji Honma Shohei Takeda Hiroshi Yamaguchi Tadatoshi Chiba Kunio Yoshida 《Chemical Engineering Communications》1981,11(6):335-345
A two-stage pressurized fluidized-bed gasification process has been developed to produce low-heating value gases from coal char. The reactor was 0.075 m id. and 1.4 m long, and gasification experiments were conducted under pressures up to 790 kPa and at temperatures up to 1323 K. A partition disc was used to divide the fluidized bed into two stages, using the first stage as a partial combuster and gasifier and the second stage as a gasifier. The disc was designed to control compositions of coal char particles in both stages so that the heat required for the endothermic gasification reaction in the second stage can be provided by the heat of combustion in the first
For conditions examined here, the disc with an opening ratio of 40° was found to give optimum distribution of the char particles in both stages without ash agglomeration. It was also shown that all oxygen gas was completely consumed within the first stage
The heating value of the product gas increased with the char feed rale. However, there may be an oplimum Teed ratio of char and sand-particles since the higher char feed rate causes more frequent ash agglomeration as well as less carbon conversion 相似文献
For conditions examined here, the disc with an opening ratio of 40° was found to give optimum distribution of the char particles in both stages without ash agglomeration. It was also shown that all oxygen gas was completely consumed within the first stage
The heating value of the product gas increased with the char feed rale. However, there may be an oplimum Teed ratio of char and sand-particles since the higher char feed rate causes more frequent ash agglomeration as well as less carbon conversion 相似文献
34.
Shigeyuki Smiya Masahiro Yoshimura Shutaro Fujiwara Ken-Ichi Kondo Akira Sawaoka Takeo Haitori Jun-Ichi Mohri Masatada Araki 《Journal of the American Ceramic Society》1984,67(3):51-C-
To enhance the sinter ability of Si3 N4 , powders mixed with 0, 2, and 5 wt% Y2 O3 were explosively shock-treated. Compacts of these powders were encapsulated in 96% silica glass containers and isostatically hot-pressed. The shocked Si3 N4 with 5 wt% Y2 O3 was pressed to a density of 3.09 g/cm3 (95.4% of theoretical) at 1400°C under 430 MPa for 3 h, whereas the unshocked material attained only 82.4% of theoretical density under the same hot isostatic pressing conditions. 相似文献
35.
Abstract The T value represents the HOMO-LUMO energy separation of a ?-electronic system weighted with the number of conjugated atoms. We found that this value is kept almost constant for the polyene references defined graph-theoretically for isolated-pentagon isomers of fullerenes with up to 100 carbon atoms. on this numerical basis, the T value can safely be considered as a realistic index of kinetic stability or chemical inertness for all fullerenes without abutting pentagons. 相似文献
36.
Ouji Y Yoshida-Terakura A Hayashi Y Maeda I Kawase M Yamato E Miyazaki J Yagi K 《Journal of Bioscience and Bioengineering》2002,94(1):81-83
In search of an efficient nonviral vector, polyethyleneimine (PEI)-based vectors were examined. In general, the transfection efficiency of nonviral vectors is suppressed by serum. Here we show that PEI based vectors, particularly, the chitosan hexamer-PEI vector, could perform efficient gene transfection into intestinal epithelial cells (IEC-6) in the presence of serum. The conjugation order of the two polymers with a plasmid (first, chitosan hexamer; second, PEI) was found to be an important factor in enhancing transfection efficiency. 相似文献
37.
In this paper we concentrate on spatial prepositions, more specifically we are interested here in projective prepositions (eg. in front of, to the left of) which have in the past been treated as semantically uninteresting. We demonstrate that projective prepositions are in fact problematic and demand more attention than they have so far been afforded; after summarising the important components of their meaning, we review the deficiencies of past and current approaches to the decoding problem; that is, predicting what a locative expression used in a particular situation conveys. Finally we present our own approach. Motivated by the shortcomings of contemporary work, we integrate elements of Lang's conceptual representation of objects' perceptual and dimensional characteristics, and the potential field model of object proximity that originated in manipulator and mobile robot path-finding. 相似文献
38.
Bulge forming of braided thermoplastic composite tubes under axial compression and internal pressure
In this study, the bulge forming of fiber reinforced thermoplastic (FRTP) composite braided tubes was studied as a new forming technique utilizing fiber orientation rearrangement (the trellis effect) at temperatures near the matrix melting point. It is shown that free bulge forming with the trellis effect can easily result in high expansion without buckling only by axial compression. This is when the stress of the matrix is small enough to rearrange the fiber orientation of the braid. To improve the surface quality and dimensional accuracy, bulge forming with closed dies and internal pressure was also examined experimentally. The appropriate conditions for axial penetration and internal pressure are established. The kinematics of braid is also considered, and calculations from the model are evaluated from experiments. In addition, the kinematic state of braid after deformation is simulated by calculation from the geometric braid model. It is found that the “normalized profile” of the bulged tube does not change during the process and the thickness of the matrix depends on changing fiber orientation. 相似文献
39.
Takaaki Matsuoka Jun-Ichi Takabatake Akihiko Koiwai Yoshinori Inoue Satoru Yamamoto Hideroh Takahashi 《Polymer Engineering and Science》1991,31(14):1043-1050
Injection molding analysis programs were developed for CAE (Computer Aided Engineering) in injection molding of thermoplastics. The programs consist of mold cooling, polymer filling-packing-cooling, fiber orientation, material properties and stress analyses. These programs are integrated to predict warpage of molded parts by using a common geometric model of three dimensional thinwalled molded parts. The warpage is predicted from temperature difference between upper and lower surfaces, temperature distribution, flow induced shear stress, shrinkage, and anisotropic mechanical properties caused by fiber orientation in the integrated simulation. The integrated simulation was applied to predicting warpage of a 4-ribbed square plate of glass fiber reinforced polypropylene for examination of its validity. Predicted saddle-like warpage was in good agreement with experimental one. 相似文献
40.
A practical design procedure for a circularly polarized printed array antenna composed of strip dipoles and slots (CP-PASS) is presented. CP-PASS is a kind of series-fed array, and the equivalent circuit model of CP-PASS is simplified to be suitable for a computer-aided design (CAD) package. Some experimental results of a new strip element excited by a stripline and a 9-element set CP-PASS are also presented. 相似文献