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121.
The pattern of shock wave reflection over a wedge is, in general, either a regular reflection or a Mach reflection, depending
on wedge angles, shock wave Mach numbers, and specific heat ratios of gases. However, regular and Mach reflections can coexist,
in particular, over a three-dimensional wedge surface, whose inclination angles locally vary normal to the direction of shock
propagation. This paper reports a result of diffuse double exposure holographic interferometric observations of shock wave
reflections over a skewed wedge surface placed in a 100 × 180 mm shock tube. The wedge consists of a straight generating line
whose local inclination angle varies continuously from 30° to 60°. Painting its surface with fluorescent spray paint and irradiating
its surface with a collimated object beam at a time interval of a few microseconds, we succeeded in visualizing three-dimensional
shock reflection over the skewed wedge surface. Experiments were performed at shock Mach numbers, 1.55, 2.02, and 2.53 in
air. From reconstructed holographic images, we estimated critical transition angles at these shock wave Mach numbers and found
that these were very close to those over straight wedges. This is attributable to the flow three-dimensionality.
相似文献
122.
The three-dimensional (3D) shock wave reflections over two perpendicularly intersecting wedges are numerically studied in
this paper, using the finite volume method which is based on the MUSCL-Hancock interpolation technique and self-adaptive unstructured
mesh. Two kinds of 3D Mach stem structures are demonstrated by the numerical simulations for different shock Mach numbers
and wedge angles. A four-shock or three-shock wave configuration appears in the vicinity of the corner of the wedges. 相似文献
123.
A series of new compounds Ln(Fe3+M2+)O4 [Ln : Y, Er, Tm, Yb, and Lu, M : Mg, Mn, Co, Cu, and Zn] were successfully synthesized and their lattice constants were determined. These compounds have the same crystal structure as YbFe2O4 and Fe3+ and M2+ are both surrounded by five oxygen ions forming a trigonal bipyramid. The synthetic conditions are presented. They are strongly dependent upon the constituent cations of the compound. 相似文献
124.
125.
This paper describes a numerical and experimental study of a micro-blast wave which is produced from the source of several
tens microns in dia. and propagates in the length scale of a few centimeter in diameter. The micro-blast wave was generated
by focusing a Nd:Glass pulsed-laser beam in ambient air. Its propagation and reflection were visualized by using double exposure
holographic interferometry and simulated numerically using the dispersion-controlled scheme to solve the Euler and Navier-Stokes
equations with initial conditions of a point-source explosion specified with the Taylor similarity law. Good agreement was
obtained between numerical solutions and experimental results, and this spherical micro-blast wave was shown to be a handy
model of blast waves created in large scale explosions.
Received 28 October 1997 / Accepted 30 April 1998 相似文献
126.
Shigeharu Takayama 《Mathematische Zeitschrift》2008,259(3):487-501
We give a uniruledness criterion on degenerate fibers in a family of varieties whose general fiber has a numerically trivial
canonical divisor. The criterion is related with the so-called non-nef locus of the canonical divisor of the total space.
相似文献
127.
A modified optimization technique, based on the response surface methodology, was developed for selecting pharmaceutical formulations. In general optimization methods, it is difficult to insure that the optimum formulation is strictly obtainable. Thus, the combined use of random number techniques and Andrews' plots with general optimization methods was investigated for seeking the optimum formulation. The method developed in this study was applied to the optimization of a sustained-release formulation based on the interpolymer complex of polyvinylpyrrolidone with carboxyvinyl polymer. Indomethacin was selected as a model drug for which sustained-release formulations are desirable. Experimental results obtained for the optimum formulation agreed well with the predictions, indicating the usefulness of this approach. 相似文献
128.
Application of streak camera photography for the study of shock wave reflections over a double wedge
The streak camera technique was employed to investigate the reflection process of a planar shock wave over a double wedge. It is shown that this technique is superior to others in precisely determining whether a Mach reflection is direct, stationary or inverse. Furthermore, it provides an excellent means of exactly determining the location of the regular to Mach reflection transition over a double wedge. 相似文献
129.
Nabuchi Y Asoh Y Takayama M 《Journal of the American Society for Mass Spectrometry》2004,15(11):1556-1564
Conformational change of calcitonins has been examined by measuring the rate of hydrogen/deuterium (H/D) exchange in amino acids. Time dependent m/z shift caused by H/D exchange was monitored by electrospray ionization quadrupole ion trap mass spectrometry (ESI-QIT MS). The rate constants of H/D exchange were calculated from apparent first-order kinetics. The time course of H/D exchange exhibited two phases of faster and slower exchange. The smaller rate constant (k2) estimated from the slower H/D exchange was correlated with an alpha-helix content that reflected the folding state. The order of k2 values obtained for human calcitonin (hCT), porcine calcitonin (pCT), salmon calcitonin (sCT), and elcatonin (ECT) was hCT > pCT approximately sCT > ECT. Although the amino acid sequence of sCT is similar to that of ECT, their k2 values were considerably different. The results suggest that ECT is relatively rigid on the N-terminal side cyclic structure in the folded state. Further, the effect of methionine oxidation on k2 has been examined. In the oxidized pCT that possesses similar biological activity with the intact pCT, the k2 values obtained were nearly equal. The k2 of hCT increased via methionine oxidation, and the biological activity was weakened by oxidation. This suggested that methionine oxidation of hCT produced unfolding in the secondary structure and that oxidative unfolding of hCT led to the loss of biological activity. The results indicate that the H/D exchange rate constant may be used as an informative parameter to elucidate the relationship between the folded state and biological activity of polypeptides like calcitonins with secondary structure. 相似文献
130.
T. Takayama T. Sekine K. Yoshihara 《Journal of Radioanalytical and Nuclear Chemistry》1993,176(4):325-331
TcN-EDTA has been synthesized for the first time starting from TcNCl4
–. Elemental analysis shows that this compound has three molecules of water of crystallization: TcN(Hedta) · 3H2O. Its optical spectrum has an absorption maximum at 505 nm with = 1060 dm3.mol–1.cm–1. It decomposed easily under alkaline conditions. 相似文献