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191.
Residual stresses in rails produced by rolling cycles are studied by a destructive testing procedure. Thin slices of rails are cut and small grid elements are made by cutting slots onto the surface of the slice. Residual stresses are believed to be released near the surface of the slice when those grid elements have right angles and are sufficiently small. The resulting deformation produced by the stress relief is measured by moiré interferometry. On assuming all strain components be constant along the longitudinal axis of the rail and this axis is one principal direction, three-dimensional strain and stress components are solved. 相似文献
192.
Kwok Wah Hui Bo Yu Wu Kin S. Chiang 《International Journal of Infrared and Millimeter Waves》1997,18(4):875-887
An analysis is given on the finite element method (FEM) for calculating the various parameters of optical modulators and a
computer program is written to solve the finite element equation. Based on this method, a Mach-Zehnder type electro-optic
modulator with coplanar waveguide (CPW) electrode is designed and fabricated. When compared with the Fourier series method,
small differences on the 3-dB bandwidth, characteristic impedance and half-wave voltage, etc. are obtained. 相似文献
193.
The branching ratio, the photoemission intensity ratio of two spin-orbit-split components, has been applied for the first time as a means for obtaining a photoelectron holographic image. Angle-resolved photoemission from a monolayer of Bi adsorbed on Si(111) shows fine-structure oscillations in the branching ratio of the Bi 5d core level due to diffraction effects. These oscillations as a function of photon energy are recorded for a number of emission angles. Three-dimensional holographic inversion of the data yields an atomic image which shows that the Bi adatoms are arranged in a trimer structure. 相似文献
194.
195.
C. Chiang 《Solid State Communications》1981,39(1):111-115
The switching and memory phenomenon in anthracene thin films is explained by assuming the polymerization of anthracene molecules to a graphite-like polymer. When the voltage is a threshold point, the energetic electron and the secondary ionization may initiate the process similar to the polymerization. Since the polymer-like entity has graphite-like structure, it has higher conductivity, thus the film is switched to ON state. Since the molecule in a thin film can not rotate as freely as in liquid, the polymer-like entity formed is under great bond strain, thus it may readily switch back to monomer anthracene molecule. However, if with repeated cycles, the polymer is at a relatively stable configuration with less bond strain, then it is in the memory state. Many experimental data of Elsharkawi and Kao may be explained with this model. 相似文献
196.
197.
198.
A complete first-order model and locally analytic solution method are developed to analyse the effects of mean flow incidence and aerofoil camber and thickness on the incompressible aerodynamics of an oscillating aerofoil. This method incorporates analytic solutions, with the discrete algebraic equations which represent the differential flow field equations obtained from analytic solutions in individual grid elements. The velocity potential is separated into steady and unsteady harmonic parts, with the unsteady potential further decomposed into circulatory and non-circulatory components. These velocity potentials are individually described by Laplace equations. The steady velocity potential is independent of the unsteady flow field. However, the unsteady flow is coupled to the steady flow field through the boundary conditions on the oscillating aerofoil. A body-fitted computational grid is then utilized. Solutions for both the steady and the coupled unsteady flow fields are obtained by a locally analytic numerical method in which locally analytic solutions in individual grid elements are determined. The complete flow field solution is obtained by assembling these locally analytic solutions. This model and solution method are shown to accurately predict the Theodorsen oscillating flat plate classical solution. Locally analytic solutions for a series of Joukowski aerofoils demonstrate the strong coupling between the aerofoil unsteady and steady flow fields, i.e. the strong dependence of the oscillating aerofoil aerodynamics on the steady flow effects of mean flow incidence angle and aerofoil camber and thickness. 相似文献
199.
J. Camassel T.C. Chiang Y.R. Shen J.-P. Voitchovsky N.M. Amer 《Solid State Communications》1976,19(6):483-485
Multiphonon resonant Raman scattering up to 4 phonons in GaSe has been measured. The results are interpreted by a simple cascade theory. It is shown that the dispersion of RRS here is dominated by resonances with the exciton states. 相似文献
200.
Railing Chang H.-P. Chiang P.T. Leung D.P. Tsai W.S. Tse 《Solid State Communications》2005,133(5):315-320
A phenomenological model for the optical response of composite materials with metallic nanoparticles is presented. This model applies the conventional effective medium theories (EMT) but takes into account the spatial dispersion effects in the dielectric response of the metallic nanoparticles. This leads to an EMT that depends on the size of the particles. Numerical results from a model computation shows that this effect due to the nonlocal optical response of the nanoparticles can increase the resonant absorption frequency of the composite significantly for particles of very small sizes; and can lead to resonant absorption even in the Bruggeman symmetric EMT—a feature which is believed to be absent in the conventional treatment where local response for the metal particles has been assumed. 相似文献