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681.
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683.
The shock is described by the Navier-Stokes equations of the electron and ion fluids, and coupled with Poisson‘s equation for the self-induced electric field. Profiles of the flow and electric variables in the weak or moderate shock front with or without current for different Debye lengths are presented. Comparison of profiles of flow and electric variables in the front for different heat flow modes is given. 相似文献
684.
探讨了一种在伴有反应的情况下测定非均相传质系数的方法,以汽、液相连续进、出料的搅拌釜和乙醇、乙酸在=1%硫酸催化下的反应体系为例,建立起相应的数学模型,并用步进搜索法求得其数值解。 相似文献
685.
MgxZn1-xO films (x = 0.23) have been prepared on silicon substrates by radio-frequency magnetron sputtering at 80℃. The structure properties of Mgx Zn1-xO films are studied using x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), x-ray photoelectron spectroscopy and Raman spectra. The analysis of XRD and HRTEM indicates that the Mgx Zn1-xO films have hexagonal wurtzite single-phase structures and a preferred orientation with the c axis perpendicular to the substrates. Raman spectra of ZnO and MgxZn1-xO films reveal that the MgxZn1-xO films have not only the hexagonal wurtzite structure but also higher crystalline quality than ZnO films. 相似文献
686.
A generalized multiresolution likelihood ratio (GMLR), which can increase the distinction between different signals by fusing their more features, is defined. Multiresolution representation of image characterizes inherent structure of image well, and the GMLR combines each resolution image features with corresponding region features. A spatially variant mixture multiscale autoregressive prediction (SVMMARP) model is proposed to estimate the parameters of GMLR based on maximum likelihood estimation via expectation maximization (EM) algorithm. In the parameter estimation, bootstrap sampling technique is employed. Experimental results demonstrate that the algorithm performs fairly well. 相似文献
687.
马洪良 《原子与分子物理学报》2002,19(2):153-155
原子光谱中,同位素移位和超精细结构光谱是少数几个能够将原子物理和原子核物理这两个不同的物理分支联系起来的课题之一.利用共线快离子束-激光光谱学方法测量了单电荷态钕离子4f45d6G3/2→(26041)°5/2跃迁(波长577.21 nm)的共振光谱,得到了所有7个稳定同位素(A=142~146,148,150)之间的能量移位和2个奇同位素(A=143,145)的超精细结构光谱. 相似文献
688.
We present a high-quality Ni/Ag/Pt Ohmic contact to p-type GaN. After the sample is annealed at 500℃ in 02 ambient for 3min, a specific contact resistance as low as 2.6 × 10^-5 Ωcm^2 and an optical reflectivity of 82% at 460 nm are obtained. The Auger electron spectroscopy analysis shows that the Pt layer can improve the surface morphology and thermal reliability of the annealed Ag-based electrode, Ag plays a key role in achieving good ohmic contact due to the outdiffusion of Ga into Ag forming Ga vacancies which increase the hole concentration, while the surface contamination of p-type GaN is reduced by Ni. 相似文献
689.
As a continuation of the investigation on 1,2-migration of metal carbene and free carbene, two X-ray structures of β-substituted α-diazocarbonyl compounds were obtained. The relationship between the structure and 1,2-migratory aptitude was discussed and an exploratory photochemical study of the diazo compounds presented. 相似文献
690.
Performances of an accelerometer suspended by a pendulum and set on ground directly are both discussed. Theoretical analysis shows that the isolation from seismic disturbances of such a suspending accelerometer is equal to that of a narrow band-pass electronic filter. This means that the effect of seismic noises to the accelerometer can be substantially suppressed by means of a pendulum suspension during its performance tests. 相似文献