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Inelastic incoherent neutron scattering spectra of D2O high-density amorphous (hda) ice, ice-Ⅷ and ice-Ⅱ mixed with small amount of H2O ((5%) have been measured recently on high-energy transfer spectrometer at Rutherford Appleton Laboratory (UK). The hydrogen atom on D2O ice lattices has three distinguished vibrational modes, two bending at low frequencies and one stretching at high frequencies, and their frequencies are slightly different for different phases of ice. It was found that the lower one of the bending modes is located at -95 meⅤ for hda-ice, at -95 meⅤ for ice-Ⅷ and at -96 meⅤ for ice-Ⅱ and they are all lower than the value of 104 meⅤ for ice-Ih. It was also measured that the O-D and O-H covalent bond stretching modes of ice-Ⅷ are at -315 and -425 meⅤ, ice-Ⅱ at 307 and -415 meⅤ, hda-ice at 312 and -418 meⅤ, respectively. They are significantly higher than the values of ice-Ih at -299 and -406 meⅤ, respectively. 相似文献
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Influence of Light Scattering on Transmission Spectra of Photonic Crystals of Anodized Alumina
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The light scattering is found to have a great influence on the transmission spectra of photonic crystal of anodic alumina. The incident light is diffracted by a regular array of branched channels or pores obeying the Bragg law. The intensity of transmission light decreases with the increasing etching time because of the increasing porosity or enlarging scatterers. The variation of intensity and widths of dips in transmission spectra of the porous alumina membrane versus the incidence angle shows the quite different characteristics from the other photonic crystal such as colloidal photonic crystal. 相似文献
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在归一化雨滴谱分布、雨滴的介电模型和Mie散射理论的基础上计算群雨滴在微波波段的散射和衰减特性,讨论分析雨滴谱分布、降雨强度、入射波频率和温度等因素对微波传输特性的影响.数值模拟结果表明,不同谱分布的群雨滴散射能力从大到小依次为JD,MP,Gamma和JT分布,降雨强度对微波传输特性的影响最大,入射波频率次之,温度的影响最小.所得出的结论有助于准确评估降雨对微波传输的影响以及提高利用测雨雷达和毫米波雷达等定量探测降水的精度.
关键词:
微波传输
雨滴谱分布
Mie散射
散射衰减特性 相似文献
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《中国物理快报》2003,20(1):14-17
When given an unknown quantum state which may be either a pure or a mixed state in the coherent state representation.we show that explicit expressions for the teleported state and its fidelity in the teleportation process(S.L.Braunstein and H.J.Kimble 1998 Phys.Rev.Lett.80 869) can be obtained without explicit expansions for the two-mode squeezed vacuum state and the Bell basis in a specified representation. 相似文献
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在研究单次散射模型的基础上, 针对单次散射模型不能对天气变化对紫外光信号造成的影响做出模拟的不足, 结合大气散射理论构建了紫外光传输的二次散射模型。研究了瑞利散射和米氏(Mie)散射在四种典型天气条件下的散射相函数, 仿真得出了紫外光被大气中的粒子散射后的能量分布情况, 将其引入二次散射模型, 并确定了各种天气条件下的散射粒子浓度后对紫外光通信系统做出性能仿真。计算结果表明, 二次散射模型可以仿真不同的天气条件下的紫外光通信系统的性能, 从仿真结果上验证了非直视通信的可实现性。并得出, 在雨、雾天气下, 紫外光信号衰减剧烈, 接收仰角不可过大; 在天气晴好时, 能更好的实现紫外光非直视通信, 接收仰角可达到180°。长距离通信时, 天气状况变化对通信性能影响更大。 相似文献
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A simple shooting method dedicated to the design of multipump discrete Raman fibre amplifiers (RFAs) ispro posed and discussed in detail. A novel scheme to provide a good initial guess for backward lightwaves is also proposed to improve the efficiency and robustness of the method. Using the proposed method, a discrete RFA with four backward pumps and 93 signal channels is simulated for the maximum number of interaction waves considered simultaneously in the RFA design reported previously; to our best knowledge. The numerical simulation results show that the proposed method is fast and robust. It can be used in the design of RFAs with various configurations including co-, counter- and bi-directJonal-pump schemes to provide an actual modelling. 相似文献
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强激光大气传输中拉曼散射的数值计算 总被引:1,自引:1,他引:0
用经典理论推导了强激光大气传输中由于氮的转动受激Ranman散射所造成的对传输功率的限制方程,并计算了光强的阈值,得到了阈光强与激光波长和脉宽的关系;此外,还研究了二维效应和激光脉冲系列通过大气时声子激发的累加效应。 相似文献
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将来的远程通信中,量子远程传输可能成为重要的手段之一.整个理论是基于量子纠缠态机制的.但是纠缠态是很脆弱的.当量子态被环境扰动时,纠缠态会被打破.在此文中,我们选择处在总自旋为0的纠缠态中的正负电子为例,研究纠缠态由于与背景辐射光子的康普顿散射或与电子经过的大天体的强磁场散射而破坏的概率.由于单个电子的自旋投影不是物理可观测量,而且,电子束由于带电粒子间的库仑斥力,不可能较长期保持成团的形状.因而只能每次只发射一对正负电子对,并不断重复这个过程.由于这些限制,此文研究只有理论上的意义,但是也许对将来如何选择信息传递信使的研究有帮助 相似文献
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为了了解光束在尾流气泡中的传输特性,为前向光尾流的探测提供理论依据,研究了光束在尾流中传输时传播方向上和横截面方向上的辐射强度分布特性.基于辐射传输方程的小角度近似解,得到了探测截面上的约化强度和漫射强度的表达式,其中漫射强度表征了复散射的强弱;针对典型的尾流气泡分布,通过数值计算分析了光束传输方向上的约化强度和漫射强度与接收视场角、光学厚度和光束大小的关系,也计算分析了光束横截面方向上的辐射强度随光束大小和横向距离的变化关系.结果表明,光束在尾流气泡中传输时复散射效应明显,且复散射的强弱与接收视场角、光束直径、光学厚度和横向距离密切相关. 相似文献
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大气环境下激光传输仿真软件的设计与编制 总被引:1,自引:0,他引:1
随着激光技术的发展,激光大气传输特性一直是激光领域的研究热点。综合激光大气传输的理论模型,运用科学的软件开发方法设计出了一套仿真系统,用来模拟激光在复杂大气环境中的辐射特性和激光的传输过程。该系统理论模型以Lambert-Beer定律为基础,结合了瑞利散射和米散射等经典理论,当在烟幕环境中模拟激光传输时,采用了多次散射模型。仿真中对大气环境采用逐段细化,每段根据数据库参数变化选取合适的计算模型,以提高仿真精度。绘制出了光斑和等位面随传输距离的演化图形,以演示激光大气的传输过程。 相似文献
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Experimental Quantum Key Distribution over 14.8 km in a Special Optical Fibre 总被引:3,自引:0,他引:3
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GUIYou-Zhen HANZheng-Fu MOXiao-Fan GUOGuang-Can 《中国物理快报》2003,20(5):608-610
We present an experimental set-up for quantum key distribution in special optical fibre at the wavelength of 850nm.The system employs the BB84 protocol to establish a secret key between Alice and Bob over 14.8km.The kdy is encoded in the phase of very weak laser of average photon number0.11 per pulse.The measured error rate is lower than 10%. 相似文献
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为了了解光束在尾流气泡中的传输特性,为前向光尾流的探测提供理论依据,研究了光束在尾流中传输时传播方向上和横截面方向上的辐射强度分布特性.基于辐射传输方程的小角度近似解,得到了探测截面上的约化强度和漫射强度的表达式,其中漫射强度表征了复散射的强弱|针对典型的尾流气泡分布,通过数值计算分析了光束传输方向上的约化强度和漫射强度与接收视场角、光学厚度和光束大小的关系,也计算分析了光束横截面方向上的辐射强度随光束大小和横向距离的变化关系.结果表明,光束在尾流气泡中传输时复散射效应明显,且复散射的强弱与接收视场角、光束直径、光学厚度和横向距离密切相关. 相似文献