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931.
932.
We present the theoretical investigation of spontaneous magnetization of a coupled 2×2 πring array. It is indicated by free energy calculation that the system has the lowest energy when the four π rings have the full antiparallel configuration. Furthermore, the numerical evaluation results show that the system which favours full antiparallel spontaneous magnetization is a quantum effect deriving from the phase cohering of the superconducting quantum wavefunctions in the four superconducting rings through the shared Josephson junctions. 相似文献
933.
A high coupling efficiency, simple structure refractive lens was designed; a hyperboloid cylinder-plane lens was proposed to reduce the divergence angle of the laser diode array beam in the fast axis direction. Based on the ray-tracing method, the shape of the input refractive surface of the designed lens is determined by numerical analysis, and designed as aspherical profile in one direction. When the beam from source point reaches the input surface of the lens, it is refracted and becomes a parallel output beam in the fast axis direction. The expressions for describing the irradiance behind the lens are also derived. 相似文献
934.
Leilei Pan 《Optics Communications》2010,283(10):2193-3220
The expressions for the spectral intensity of partially coherent Gaussian Schell-model (GSM) radial array beams for both the correlated and uncorrelated superpositions passing through ABCD optical systems have been derived by using the extended Huygens-Fresnel diffraction integral. The effects of the normalized radius R, the number of beamlets N, the spatial coherent parameter of array beamlets β and the optical system parameters on the on-axis and off-axis relative spectral shifts for the two types of superposition have been discussed in detail. The results show that for the correlated superposition, the on-axis spectral intensity in free space and the off-axis spectral intensity on the geometrical focal plane depends on the source spectral density S0(ω), the spatial coherent parameter of array beamlets β, the generalized Fresnel number of the system F, the normalized radius R and the number of beamlets N, whereas the spectral intensity for the uncorrelated superposition is independent of the number of beamlets N. Furthermore, as for on the actual focal plane, the off-axis spectral intensity for the two types of superposition is closely related to N. 相似文献
935.
为了解决太阳模拟灯阵整体放在真空罐内使用时的导热问题,采用热管导热的方案,设计了专门的氙灯导热机构。计算了液氮系统的导热能力,结果显示,真空罐液氮冷却系统的温度升高ΔT为2074 1 K,小于其过冷度4 K,表明真空罐液氮冷却系统完全可以将太阳模拟灯阵的热量导出。采用热管导热技术,设计了导热机构,用有限元分析法进行了热仿真分析,分析结果表明,氙灯阴阳极温度维持在100 ℃左右,氙灯灯泡维持在655 ℃左右,满足氙灯正常工作的温度条件;积分器和反射镜组件温度维持在200 ℃左右,椭球镜温度维持在135 ℃左右,亦满足正常工作的温度条件,从而验证了热设计的正确性。 相似文献
936.
937.
推导出矩形分布高斯-谢尔模型(GSM)列阵光束通过湍流大气传输的等效曲率半径的解析表达式。研究表明,等效曲率半径由湍流强度、GSM列阵光束参数及光束的叠加方式等因素共同确定。湍流使得等效曲率半径减小,但湍流对交叉谱密度函数叠加时等效曲率半径的影响要比光强叠加时大。在自由空间中,交叉谱密度函数叠加时GSM列阵光束的等效曲率半径要比光强叠加时的大。但是,随着湍流的增强,交叉谱密度函数叠加时GSM列阵光束的等效曲率半径可以大于、等于或小于光强叠加时的等效曲率半径。此外,若光束相干参数和子光束数目越大,则等效曲率半径受湍流的影响越大。GSM列阵光束的等效曲率半径受湍流的影响比高斯列阵光束要小。 相似文献
938.
Hui ZhaoWuyou Fu Haibin YangYang Xu Wenyan ZhaoYanyan Zhang Hui ChenQiang Jing Xuefeng QiJing Cao Xiaoming ZhouYixing Li 《Applied Surface Science》2011,257(21):8778-8783
TiO2/Fe2O3 core-shell nanocomposition film has been fabricated via two-step method. TiO2 nanorod arrays are synthesized by a facile hydrothermal method, and followed by Fe2O3 nanoparticles deposited on TiO2 nanorod arrays through an ordinary chemical bath deposition. The phase structures, morphologies, particle size, chemical compositions of the composites have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and ultraviolet-visible (UV-vis) spectrophotometer. The results confirm that Fe2O3 nanoparticles of mean size ca. 10 nm coated on the surface of TiO2 NRs. After depositing Fe2O3, UV-vis absorption property is induces the shift to the visible-light range, the annealing temperature of 600 °C is the best condition for UV-vis absorption property of TiO2/Fe2O3 nanocomposite film, and increasing Fe content, optical activity are enhanced one by one. The photoelectrochemical (PEC) performances of the as-prepared composite nanorods are determined by measuring the photo-generated currents under illumination of UV-vis light. The TiO2 NRs modified by Fe2O3 show the photocurrent value of 1.36 mA/cm2 at 0 V vs Ag/AgCl, which is higher than those of unmodified TiO2 NRs. 相似文献
939.
In this work the moving ultrasound linear array technique has been used to perform 3D echographic images of different human hands, in order to evaluate this technique to biometric recognition purposes. An automated set up, based on a commercial echographic machine provided with a high frequency (12 MHz) linear array, has been built up. The probe is moved in the direction orthogonal to the array and at each step a B-scan is performed and stored to form a 3D matrix representing the under skin hand volume.B-scan and C-scan images of the hand of different users were analysed and compared. The results have shown that, in the analysed region (about 10 mm under the palm skin), there are several anatomic elements (including hand bones, bending tendons, muscle tissue, blood vessels) that can be exploited for measurements of biometric parameters.The characteristics of the proposed technique are compared with those of the 2D optical hand geometry, which is a well established biometric technique, and its possible advantages are underlined and discussed. 相似文献
940.
针对光纤传输和干涉成像阵列中的相位误差, 提出了一种基于特殊光子晶体的全息相位校正方法。首先分析了光纤干涉阵列成像的基本原理和相位信息的传输过程, 以一维线性阵列建立成像系统相位误差模型, 通过对参考光束和探测器前的快门交替打开和闭合, 来分别实现在晶体上写入由光纤阵列的出射光束与参考光束干涉形成的含有相位误差的光栅函数, 和光纤中出射光束被该光栅衍射和相位偏移以消除相位误差, 从理论上分析了上述基于光子晶体的全息法相位校正原理。最后采用所建立的含有相位误差的干涉阵列进行成像仿真, 对未加校正、采用本文方法和采用冗余基线校正的结果进行了对比分析。 相似文献