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161.
Digital shifting photoelasticity with optical enlarged unwrapping technology for local stress measurement 总被引:1,自引:0,他引:1
Xue-Feng Yao Long-Hui Jian Wei Xu Guan-Chang Jin Hsien-Yang Yeh 《Optics & Laser Technology》2005,37(7):582-589
In this paper, photoelasticity combined with phase shifting technology is used to obtain stress distribution within the stress concentration zone. Both the optical enlarged unwrapping technology and the combined path shear difference technology are provided for evaluating the local stress information. By means of a phase shifting photoelastic experiment of a diametric-compressed disc, the stress components surrounding the local loading zone are determined. The results show not only a good improvement compared with conventional photoelastic analysis but also a good agreement with theoretical data. 相似文献
162.
Siao‐Wei Yeh Tzung‐Luen Wu Kung‐Hwa Wei Ya‐Sen Sun Keng S. Liang 《Journal of Polymer Science.Polymer Physics》2005,43(10):1220-1229
Surface‐modified CdS nanoparticles selectively dispersed in hexagonally packed poly(ethylene oxide) (PEO) cylinders of poly(styrene‐b‐ethylene oxide) (PSEO) block copolymers were prepared. The photoluminescence and ultraviolet–visible characteristics of the presynthesized CdS nanoparticles in N,N‐dimethylformamide and in PEO domains of the PSEO block copolymers were determined. Because of strong interactions between the CdS nanoparticles and PEO chains, as shown by Fourier transform infrared spectroscopy, the incorporation of the CdS nanoparticles prevented the PEO cylinders from properly crystallizing; this was confirmed by differential scanning calorimetry and wide‐angle X‐ray diffraction measurements. The intercylinder distance between the swollen and reduced‐crystallinity CdS/PEO cylinders in turn increased, as confirmed by small‐angle X‐ray scattering and transmission electron microscopy. At a high CdS concentration (43 wt % or 8.3 vol % with respect to PEO), however, the hexagonally packed cylindrical nanostructure of the PSEO diblock copolymers was destroyed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1220–1229, 2005 相似文献
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A frequency selective coupler which consists of two thin film waveguides imbedded in a periodic medium is studied using the Brillouin diagram. Detailed results for the relative bandwidth and the coupling factor are plotted as a function of normalized frequency for a representative case. 相似文献
165.
Magnetoelastic excitations with a fine structure in the 50kHz range have been observed in the study of the domain wall resonance (DWR) in magnetic garnet thin films. DWR excites standing transverse elastic waves which have a resonance frequency given by , where f is the frequency, n is an integer, v=3.5×105 cm/sec is the transversal velocity of the elastic wave, and d=0.05 cm is thickness of the film/substrate system. A fine structure associated with each of these modes has been identified as due to two dimensional bulk elastic waves by using a set of parallel microstrip lines. The dispersion relation of these elastic waves is ω2=v2(k21+k22), where ω is the radial frequency, k1 and k2 are the wave vectors in the orientation perpendicular and parallel to the sample surface respectively. In the case of k1?k2, , where f0 is the resonance when k2=0. The experimental results are in excellent agreement with this model. A linear dispersion, observed when using a shorted slot-line structure, is understood as the excitation of three dimensional modes due to the complex structure of the slot-line and the sample geometry. 相似文献
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167.
G. T. Yeh 《国际流体数值方法杂志》1984,4(3):231-246
This paper presents the development of a channel hydrodynamic model for simulating the behaviour of flows and water depths in a river network that may consist of any number of joined and branched rivers/streams, including both tidal and non-tidal rivers. The model employs a numerical method—an integrated compartment method (ICM). The method greatly facilitates the set-up of algebraic equations for the discrete field approximating the corresponding continuous field. Most of the possible boundary conditions that may be anticipated in real-world problems are considered. These include junctions, prescribed flow, prescribed water depth (or cross-sectional area), and rating curve boundaries. The use of ICM makes the implementation of these four types of boundary conditions relatively easy. The model is applied to two case studies: first to a single river and then to a network of five river branches in a watershed. Results indicate that the model can simulate the behaviour of the hydrodynamic variables that are required to compute chemical transport in a river-stream network. 相似文献
168.
Dashing Yeh 《BIT Numerical Mathematics》1983,23(1):36-48
A method is described to augment an ordinary shift-reduce parser into an incremental one. To parse a modified input, the resulting incremental parser requires about 3(n+m) space and runs in time roughly proportional tom, wheren is the length of the original input andm is the size of the modification made. 相似文献
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