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71.
Development of a numerical wave tank for analysis of nonlinear and irregular wave field 总被引:9,自引:0,他引:9
A numerical wave-absorption filter has been developed for an open boundary condition in the analysis of nonlinear and irregular wave evolution. The filter is composed of a simulated sponge layer and Sommerfeld's radiation condition at the outer edge of the layer. The wave-absorption characteristics of the filter have been investigated by applying the linear potential theory and a two-dimensional nonlinear boundary element model. In both cases, the filter is found to he applicable for a wide range of wave parameters. In order to realize an idealized “numerical wave tank”, the present model also incorporates a nonreflective wave generator in the computational domain composed of a series of vertically aligned point sources. Numerous numerical experiments demonstrate that the present approach is effective in generating an arbitrary wave profile without reflection not only at the open boundaries but also at the wave generator. 相似文献
72.
Masato Suzuki Ken-ichi Fujii Tyuzi Ohyama Hiromi Kobori 《International Journal of Infrared and Millimeter Waves》2003,24(12):2043-2050
We have investigated resonant Faraday effect (RFE), so-called nonlinear Faraday effect, caused by conduction and donor electrons in n-InSb and n-GaAs. Experiments were carried out with using the magneto-optical spectroscopic system combined with two linear polarizers put in before and behind a sample. The rotation angle and the ellipticity for the far-infrared light with elliptical polarization transmitted through the sample were analyzed on the basis of spectra obtained under different experimental configuration for angles between the axes of the polarizer and the analyzer. We have observed some characteristic features associated with RFE in spectra of two samples. Tapping into these features, we could successfully determine the relaxation times and the densities of conduction and donor electrons in the semiconductors. 相似文献
73.
Tokiya Abe Yuri Murakami Masahiro Yamaguchi Nagaaki Ohyama Yukako Yagi 《Optical Review》2005,12(4):293-300
Pathological images are color images of stained tissue slides, the color of which varies depending on staining conditions. For reliable diagnosis, the color variation must be corrected in these images. This paper proposes a color correction method for hematoxylin and eosin (H&E) stained pathological images in which the amounts of H&E dyes are estimated based on multispectral imaging technique and Beer Lambert law, and the color image is generated corresponding to the adjusted amount of dyes. This enables us to correct an image to an arbitrary or specified optimal staining-condition image. Through experiments using H&E stained human liver slide images, the effectiveness of the proposed method was confirmed. 相似文献
74.
SPECT (single photon emission computed tomography) images can visualize physiological functions directly and are diagnostically useful. The reconstruction methods based on the Continuous-Discrete (C-D) mapping model have an immediate effect on SPECT imaging because they employ photon detection kernels describing the photon transport from the body to the detector. However, in a spatially varying focal length geometry, the concentration of the sensitivity around the center of rotation of the detector causes a change in the response from the original image to the reconstructed image. As a result, a false hot spot often appears around the center of rotation. This paper presents a convenient method to repress the change by correcting the resolving kernels. Numerical simulations show that the method can reduce the false hot spots. 相似文献
75.
76.
The thermoelectric power (TEP) has been measured from 2.2 to 300 K for antiferromagnetic compounds, CeIn3, NdIn3, SmIn3, GdIn3 and (Ce1−xLax)In3 with x = 0.1 and 0.2. The effects of the antiferromagnetic order were observed on the TEP of these compounds below TN. The observations are explained by the antiferromagnetic band gap formation theory proposed by Abel'skii. 相似文献
77.
78.
Eizo Otsuka Tyuzi Ohyama Ken-ichi Fujii 《International Journal of Infrared and Millimeter Waves》1984,5(2):159-169
Far-infrared laser cyclotron resonance with the help of photoexcitation enables us to separate the electron-neutral donor and electron-neutral acceptor scattering rates in GaAs. Allowing for the complication due to the coexistence of donors and acceptors, inaccuracy due to unknown contribution of phonon scatterings etc., one finds that the electron-neutral donor scattering cross-section is 2.9×10–11 cm2 at 4.2 K, that is 23 times as large as the electron-acceptor scattering cross-section. 相似文献
79.
80.
We have investigated optically detected cyclotron resonance (ODCR) and ordinary cyclotron resonance (CR) under the same condition, in Ge and Si, which include both high-purity and doped samples. In impact dissociation processes, which are the origin of ODCR, donorbound excitons have larger cross section for impinging electrons than for holes, and conversely, acceptor- bound excitons have larger cross section for holes than for electrons. Moreover, the ratio of impact dissociation cross section for holes to that for electrons varies with the number of excitons bound to an impurity. These phenomena are understood primarily in terms of exchange interaction between impinging carriers and constituents of bound excitons. In addition, it is found that the relative intensity of hole cyclotron resonance against electron resonance is larger in ODCR than in CR. This is understood in terms of exchange interaction by taking the many valley nature of the conduction band into account. 相似文献