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排序方式: 共有594条查询结果,搜索用时 15 毫秒
71.
Mitsuhiro Ohta Daisuke Kikuchi Yutaka Yoshida Mark Sussman 《International Journal of Multiphase Flow》2011
The dynamics of bubble formation from a submerged nozzle in a highly viscous liquid with relatively fast inflow gas velocity is studied numerically. The numerical simulations are carried out using a sharp interface coupled level set/volume-of-fluid (CLSVOF) method and the governing equations are solved through a hydrodynamic scheme with formal second-order accuracy. Numerical results agree well with experimental results and it is shown that the sharp interface CLSVOF method enables one to reproduce the bubble formation process for a wide range of inflow gas velocities. From numerical results, one can improve their understanding of the mechanisms regarding the dynamics of bubble formation. For example, it is found that for some sets of parameters that the bubble formation process reaches steady state after several bubbles are released from the nozzle. At steady state, bubbles uniformly rise freely in the viscous liquid. It is observed that the fluid flow around a formed bubble has a significant role in determining the overall dynamic process of bubble formation; e.g. the effect of the fluid flow from the preceding bubble can be seen on newly formed bubbles. 相似文献
72.
Preparation of Cu2ZnSnS4 thin films by hybrid sputtering 总被引:2,自引:0,他引:2
Tooru Tanaka Takeshi Nagatomo Mitsuhiro Nishio Akihiro Wakahara Hiroshi Ogawa 《Journal of Physics and Chemistry of Solids》2005,66(11):1978-1981
In order to fabricate Cu2ZnSnS4 thin films, hybrid sputtering system with two sputter sources and two effusion cells is used. The Cu2ZnSnS4 films are fabricated by the sequential deposition of metal elements and annealing in S flux, varying the substrate temperature. The Cu2ZnSnS4 films with stoichiometric composition are obtained at the substrate temperature up to 400 °C, whereas the film composition becomes quite Zn-pool at the substrate temperature above 450 °C. The Cu2ZnSnS4 film shows p-type conductivity, and the optical absorption coefficient and the band gap of the Cu2ZnSnS4 film prepared in this experiment are suitable for fabricating a thin film solar cell. 相似文献
73.
74.
Electron-microscopic texture and physical properties of a styrene–butadiene–styrene (SBS) block copolymer obtained by casting from toluene, carbon tetrachloride, ethyl acetate, and methyl ethyl ketone are discussed. Two peaks are observed in the mechanical loss (tan delta;) curve at ?70 and 100°C which are attributed to segmental motion of polybutadiene and polystyrene, respectively. The polybutadiene peak heights are in the order of solubility in the solvent used; the polystyrene peak heights are in converse order. In addition to these peaks, a third peak is observed at 10°C for specimens cast from ethyl acetate or methyl ethyl ketone. A transition corresponding to this peak is also noticed in thermal analysis. It is proposed that aggregation of styrene blocks is relatively incomplete in specimens cast from solution in poor solvents. 相似文献
75.
Covariant canonical quantization of the bosonic string is performed, based on the BRS invariance principle. Defining a physical state by a modified form of Kugo-Ojima's subsidiary condition QB|phys〉 = 0 (QB = BRS charge), we prove a no-ghost theorem in a simple manner. There an interesting relation between critical dimension and BRS symmetry is noticed; namely, the conditions D = 26 and α0 = 1 for the space-time dimension D and the zero-intercept α0 of leading trajectory are required by the nilpotency QB2 = 0 of the BRS charge. In addition, ghost number fractionization is observed in this system. 相似文献
76.
77.
Aizawa T Kanakubo M Hiejima Y Ikushima Y Smith RL 《The journal of physical chemistry. A》2005,109(33):7353-7358
Local density augmentation around exciplex between acetophenone and N,N,N',N'-tetramethylbenzidine in supercritical water was measured by observing the peak shift of transient absorption spectrum at temperatures from 380 to 410 degrees C and at pressures from 6 to 37 MPa. Large local density augmentation was observed at lower solvent densities. Local density augmentation was evaluated by the excess density, which was defined as the difference between local density and bulk density, and the density enhancement factor, which was defined by the ratio of the local density to the bulk density. The number of solvating molecules was estimated with a Langmuir adsorption model. The excess density was found to exhibit a maximum at approximately 0.15 g cm(-3), which decreased with increasing temperature. The density enhancement factor was found to decrease with increasing temperature; however, its value was much greater than unity at 410 degrees C, which provides evidence that exciplex-water interactions still exist at these conditions. The temperature dependence of local density augmentation around the exciplex in supercritical water was comparable with that in supercritical carbon dioxide, which suggests that the ratios of the solute-solvent and solvent-solvent interactions are comparable between these two systems. 相似文献
78.
Mitsuhiro Itoh 《Journal of Geometric Analysis》2005,15(1):63-81
Study of modified scalar curvatures and the modified Yamabe problem is given. An existence theorem of type of Trudinger and
Aubin is obtained. Interpreting Isotropic curvature as a certain modified scalar curvature we can extend the four-dimensional
sphere theorem of [23]. Another modified scalar curvature is used in solving open problems concerning the conjecture of self-dual
Einstein 4-manifold and the Goldberg conjecture, both being under negative Ricci condition. 相似文献
79.
80.
A novel in-needle sample preparation device has been developed for the determination of volatile aldehydes in gaseous samples.
The needle device is designed for the gas chromatographic (GC) analysis of aldehydes and ketones commonly found in typical
in-house environments. In order to prepare the extraction device, a bundle of polymer-coated filaments was longitudinally
packed into a specially designed needle. Derivatization reactions were prompted by 2,4-dinitrophenylhydrazine (NDPH) included
in the needle, and so the aldehydes and ketones were derivatized to the corresponding hydrazones and extracted with the extraction
needle. A reproducible extraction needle preparation process was established, along with a repeatable derivatization/extraction
process that ensures the successful determination of aldehydes. The storage performance of the extraction needle was also
evaluated at room temperature for three days. The results demonstrate the successful application of the fiber-packed extraction
device to the preparation of a gaseous sample of aldehydes, and the future possibility of applying the extraction device to
the analysis of in-house environments. 相似文献