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A Simple Calculation Approach for the Second-Harmonic Sound Beam Generated by an Arbitrary Distribution Source
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We present a simple calculation approach for the fundamental and second-harmonic sound beams with an arbitrary distribution source in the quasilinear approximation. The analysis is based on the assumption that the source function with an arbitrary geometry and distribution is expanded into the sum of a set of two-dimensional Gaussian functions. The two- and five-dimensional integral solutions for the fundamental and second-harmonic fields are, respectively, reduced in terms of Gaussian functions and simple one-dimensional integrals. The numerical evaluation of field distributions is then greatly simplified. 相似文献
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Stable monolayers of electropolymerized poly-N-vinylcarbazole (EPVK) and arachidic acid(AA) are obtained on a subphase of alkaline Tl2O3 colloidal solutions. As revealed by the atomic force microscope, there is phase separation in the mixed LB monolayers. Transmission electron microscopic observations reveal that ordered arrays of composite Tl2O3/Epvk nanowires are formed in the mixed monolayers. Formation of the composite nanowire arrays is attributed to the ordered adsorption of Tl2O3 colloidal particles along the polycationic EPVK chains. The composite nanowire array is 3.2nm wide with a spacing of 2.7nm.The composite nanowire arrays can also be formed when pure EPVK is used. Composite LB multilayers of Tl2O3/EPVK nanowire arrays are prepared. The bilayer spacing is 5.54nm.The present study is of importance to the fabrication of inorganic semiconductor/functional polymer composite nanowires. 相似文献
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用原子力显微镜研究了二棕榈酰磷脂酸(DPPA)双层LB膜的分子排列结构,发现DPPA双层膜的分子排列具有长程的位置和取向有序,为有序大方结构,同时,在DPPA双层膜的极性区磷酸基团间存在局域超分子结构。 相似文献
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锥形声源的二次谐波声场分布 总被引:1,自引:0,他引:1
本文推导了锥形声源的非线性二次谐波声场分布。理论表明锥形源二次谐波声场沿径向呈Bessel函数分布,且与传播距离无关。另一个重要结论是这种声场的二次谐波束宽刚好为基波的1/2,而非一般情况下的1/倍,此外,我们指出了这种声束在非线性参量B/A成象或测量中潜在的应用价值. 相似文献
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依托实体医院线下资源,基于运营商行业云平台和视频平台基础能力,构建平台资源弹性配置、按需扩容,应用功能按需扩充、快速迭代的新一代互联网医院平台.通过线上线下系统联动,实现诊前智能导诊与精准预约、诊中在线咨询与实时问诊、诊后智能慢病管理与院后随访的全流程在线医疗服务,最终优化医院服务流程和品质,提升优质医疗资源服务范围和... 相似文献
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We present a further analysis for the second-harmonic generation of Bessel beams in lossy media.The emphasis is put on the effect of absorption to the radial pattern of the second-harmonic beam.It is shown that within the absorption length of the second harmonic,the Bessel second-harmonic beam approaches limited diffraction in the radial direction and behaves as in the case of lossless media. 相似文献
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本文对"信息电子技术中的场与波"实验教学改革进行了探讨。笔者分析了现阶段实验教学的困难并提出了解决此类困难的一些可行方法。根据该课程主要包括微波和光导波两部分的特点,在充分利用现有资源的基础上,课程组设计了微波系统与光波系统两个实验。实践表明:通过实验教学的改革与实践,激发了学生的学习兴趣,从而提高了教学质量。 相似文献