排序方式: 共有92条查询结果,搜索用时 15 毫秒
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We report an experimental observation of Poisson's spot with pseudo-thermal light. The experimental results show that the diffraction pattern disappears in the intensity distribution behind the opaque disc but emerges through both auto-correlation and cross-correlation intensity measurements. The auto-correlation scheme can take care of both better visibility and higher resolution of the diffraction pattern under the condition that the thermal light source has a larger spectral bandwidth. 相似文献
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A new discrete fractional transform defined by two parameters (angle and fractional order) is presented. All eigenvectors of the transform are obtained by an angle using recursion method. This transform is named as discrete fractional angular transform (DFAT). The computational load of kernel matrix of the DFAT is minimum than all other transforms with fractional order. This characteristics has very important practical applications in signal and image processing. Numerical results and the mathematical properties of this transform are also given. As fractional Fourier transform, this transform can be applied in one and two dimensional signal processing. 相似文献
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This paper proposes simple models of polymer networks with sliding junctions for molecular simulation and reports the main results obtained by Brownian dynamics on the elastic properties of networks with tri-functional sliding junctions. The stress-strain relation for isotropic swelling and uniaxial deformation are obtained and compared with those of the conventional chemical gels. We find that mobility and distribution of sliding junctions along the polymer chains drastically change with deformation, and lead to new profiles of the stress. We also find that sliding junctions aggregate by deformation, resulting in the decrease in the number of elastically effective chains. 相似文献
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The effects of γ-radiation on the spectrophotometric determination of uranium as the thiocyanate complex in water and acetone-water solutions have been studied. When tin(II) chloride is present, the absorbance of uranium thiocyanate in aqueous solution decreases with increasing radiation dose until the appcarance of radiolytic elemental sulfur causes an apparent increase. In the absence of tin(II) chloride, the turbidity caused by radiolytic sulfur causes an increase in absorbance over the whole dose range studied. In acetone-water solution, similar but much more severe effects occur. Observations of radiation effects of some of the individual reagents used in the spectrophotometric determinations are included, as well as indications of the errors caused by specific radiation doses. 相似文献
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Yasutaka Hanada Koji Sugioka Ikuko Shihira Ishikawa Katsumi Midorikawa 《Applied Surface Science》2009,255(24):9893-9897
We demonstrate fabrication of microchips with microfluidic structures for dynamic analysis of living cells using a femtosecond (fs) laser. Fs laser direct writing followed by annealing and successive wet etching in dilute hydrofluoric (HF) acid solution resulted in formation of three dimensional (3D) hollow microstructures embedded in photostructurable glass. The embedded microchannel structure enabled us to analyze unique phenomenon of Cryptomonas, which suddenly swims very fast under certain condition. Vector analysis of the driving force for the rapid motion was also carried out by introducing nano-beads into the microchannel, in which Cryptomonas was encapsulated. We also fabricated a microchip for observation of Phormidium moving toward a seedling root, which accelerates growth of the seedling. Using the embedded microchannel in the microchip, observation of Phormidium assemblage to the seedling root was easily carried out. Such microchips with microfluidic structures, referred to as a nano-aquarium, realize the efficient and highly functional observation of living cells. 相似文献
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We report on a new experiment in which ghost imaging and ghost interference with quasi-thermal light are simultaneously obtained from the same set of experimental reference patterns. By sliding the mask along the object arm in a continuous way, one can see imaging and diffraction patterns to come to light and fade out in opposite directions. 相似文献
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GaN have sphalerite structure (Cubic-GaN) and wurtzite structure (hexagonal GaN). We report the H-GaN epilayer with a LT-AlN buffer layer has been grown on Si(1 1 1) substrate by metal-organic chemical vapor deposition (MOCVD). According to the FWHM values of 0.166° and 14.01 cm−1 of HDXRD curve and E2 (high) phonon of Raman spectrum respectively, we found that the crystal quality is perfect. And based on the XRD spectrum, the crystal lattice constants of Si (a = 5.3354 ?) and H-GaN (aepi = 3.214 ?, cepi = 5.119 ?) have been calculated for researching the tetragonal distortion of the sample. These results indicate that the GaN epilayer is in tensile strain and Si substrate is in compressive strain which were good agreement with the analysis of Raman peaks shift. Comparing with typical values of screw-type (Dscrew = 7 × 108 cm−2) and edge-type (Dedge = 2.9 × 109 cm−2) dislocation density, which is larger than that in GaN epilayers growth on SiC or sapphire substrates. But our finding is important for the understanding and application of nitride semiconductors. 相似文献
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P. Tassin 《Optics Communications》2006,264(1):130-134
We study Veselago’s lens with arbitrary index of refraction and characteristic impedance. Using a full wave optics calculation, we show that this lens can be considered as an imaging system and we derive the appropriate lens formula. The lens with arbitrary index and impedance retains some of the properties of the matched lens, such as the invariance of its optical axis, three-dimensional imaging and easy manufacturing, but it loses the property of sub-wavelength resolution. We also show that identical results can be obtained for the impedance matched lens in the framework of paraxial geometrical optics, from which it can be inferred that optical systems containing such a lens can be studied and designed using traditional ray-tracing tools. 相似文献