共查询到18条相似文献,搜索用时 218 毫秒
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光纤通信领域中引起人们广泛关注的物理问题是光纤中的非线性效应,其中包括光纤受激喇曼散射和布里渊散射(BSRS,BSBS)、光纤克尔效应(BKF)、光纤四波混频(BFWM)、光纤自相位调制(BSPM)与光孤子(Soliton)效应等.这些效应赋予光纤以“主动性”,为其开辟了广阔的重要应用前景.本文从这些效应的基础─—耦合波方程出发,简明地阐述了它们的物理机制,并给出了一些有实际意义的重要结果,包括BSBS和BSRS的增益G、有效光纤长度L以及它们的临界功率PBc和PRc,BKF的偏振特性,BSPM的临界功率 Pc,BFWM的相位匹配条件和新方法等等.文中还对这些效应在光放大等方面的应用以及目前的水平等作了概要介绍. 相似文献
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两种偏最小二乘分光光度法同时测定三组分混合物 总被引:1,自引:0,他引:1
本文研究两种偏最小二乘法(经典编最小二乘法(CPLS)和基于核心矩阵的偏最小二乘法(KPLS)同时测定三组分混合物,根据数学原理编制三个程序(SPGRAFA,SPGRPLS和SPGRKPLS)执行这些计算,八个误差函数用以推断因子数目,因为核心矩阵维数小于原始数据矩阵,所以KPLS法适于计算具有较多光谱数和较少样品数的数据矩阵,实验结果显示对相互重叠的光谱用这两种方法均能获得令人满意且十分吻合的结 相似文献
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一种用于ICP光谱法直接分析海水样品的高盐雾化器的应用研究 总被引:1,自引:0,他引:1
制作了适用将海水样品直接进样喷入ICP焰的高盐雾化器,连续进样喷雾12分半钟不堵塞,测定了海水中的元素Sr,Ba,P,B,Ca,K,Li的检出限(DL)和BEC值,其结果相当于或优于ARL-MDSN高盐雾化器的DL和BEC值。 相似文献
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碳氢碳氟表面活性剂混合胶束的NMR和ESR研究 总被引:6,自引:0,他引:6
用NMR,ESR和表面张力测量研究了3-十二烷氧基-2-羟丙基磺酸钠(SDEHS)与全氟辛酸钠(SPFO)混合溶液微环境性质,表面张力测定表明长链烷基磺酸盐中嵌入羟丙基后,其表面活性提高,而与SPFO混合溶液的表面活性高于单一的SDEHS和SPFO,NMR和ESR研究表明,SDEHS的碳氢链与SPFO的碳氟链之间有强烈的相互作用,SDEHS与SPFO形成混合胶束,混合胶束“界面”的微观粘度较SDE 相似文献
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KrF激光在SF_6气体中受激布里渊散射的研究 总被引:2,自引:1,他引:1
用线宽0.5cm ̄(-1)、脉宽23ns的KrF激光(248nm)在低气压SF_6气体中进行受激布里渊散射(SBS)的实验研究。测量了SBS反射率随泵浦光能量、气体气压、透镜焦距等实验条件的变化关系,分析和讨论了气体气压、透镜瑞利范围对SBS阈值的影响。 相似文献
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本文研究了电热蒸发电感耦合等离子体原子发射光谱(ETV-ICP-AES)中氯化物,高氯酸等产生的干扰,并且与无火焰石墨炉原子吸收(GFAAS)中这些基体的干扰作了比较,认为酸等产生的干扰,并且与无火焰石墨炉原子吸收(GFAAS)中这些基体的干扰作了比较,认为ETV-ICP-AES的干扰比GFAAS干扰小。本文还对这两种方法中干扰的差异作了一些探讨。 相似文献
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X光针孔成像是惯性约束聚变(ICF)研究中重要的诊断方法,对其点扩散函数的计算可用于图像重建和系统空间分辨的判断。对菲涅耳衍射公式进行了化简,分析了X光能点、针孔尺寸及放大倍率对针孔点扩散函数的影响。实验在保证成像能获得足够高信噪比的条件下,通过模拟获得在最佳空间分辨时所要的针孔大小、放大倍率和X光能点等参数。在流体力学不稳定性的静态样品定标实验中,通过模拟获得了针孔的调制传递函数(MTF),结合实验测量的结果反推获得分幅相机本身的MTF值。同时采用测刀边函数的方法获得了分幅相机本身的刀边函数,进而得到相机在各空间频率下的MTF值。两种方法得到的分幅相机MTF值一致,验证了通过菲涅耳衍射模拟X光针孔成像的可行性。 相似文献
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盲反卷积方法在水下激光图像复原中的应用 总被引:1,自引:0,他引:1
由于水体对激光存在着吸收和散射效应,距离选通水下激光成像系统所获得的图像存在不同程度的劣化问题,具有信噪比低、边缘模糊等特点。为提高图像质量,在分析水下激光成像劣化过程的基础上,研究了水下激光图像的基本噪声特征,并结合点扩展函数和调制传递函数,利用威尔斯小角度近似理论,将盲反卷积方法应用到水下激光图像复原中。在进行盲反卷积图像复原时,比较和讨论了将原始图像和经过降噪处理后的图像分别作为初始输入的处理结果;并对当人为改变调制传递函数和点扩展函数时所得到的图像复原结果进行了研究和讨论。处理结果表明该方法能达到抑制背景噪声、突出目标细节、提高对比度的效果,对水下激光图像增强十分有效。 相似文献
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Polarization ratio characteristics of electromagnetic scattering from sea ice in polar areas 下载免费PDF全文
《中国物理 B》2018,(12)
In the global climate system, the polar regions are sensitive indicators of climate change, in which sea ice plays an important role. Satellite remote sensing is a significant tool for monitoring sea ice. The use of synthetic aperture radar(SAR) images to distinguish sea ice from sea water is one of the current research hotspots in this topic. To distinguish sea ice from the open sea, the polarization ratio characteristics of sea ice and sea water are studied for L-band and C-band radars, based on an electromagnetic scattering model of sea ice derived from the integral equation method(IEM) and the radiative transfer(RT) model. Numerical experiments are carried out based on the model and the results are given as follows. For L-band, the polarization ratio for sea water depends only on the incident angle, while the polarization ratio for sea ice is related to the incident angle and the ice thickness. For C-band, the sea water polarization ratio is influenced by the incident angle and the root mean square(RMS) height of the sea surface. For C-band, for small to medium incident angles,the polarization ratio for bare sea ice is mainly determined by the incident angle and ice thickness. When the incident angle increases, the RMS height will also affect the polarization ratio for bare sea ice. If snow covers the sea ice, then the polarization ratio for sea ice decreases and is affected by the RMS height of snow surface, snow thickness, volume fraction and the radius of scatterers. The results show that the sea ice and the open sea can be distinguished by using either L-band or C-band radar according to their polarization ratio difference. However, the ability of L-band to make this differentiation is higher than that of C-band. 相似文献
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An angular cutoff composite model for investigation on electromagnetic scattering from two-dimensional rough sea surfaces 下载免费PDF全文
Based on the local configuration angle division to select the corresponding method for electromagnetic scattering calculation from rough sea surface,this paper presents an angular cutoff composite model:when the local scattered angle is in the specular region that is given by an approximately 20 degrees cone around the specular direction,the Kirchhoff approximation is applied to evaluate the specular reflection,which dominates the total scattering in this region;the small perturbation method is employed to handle the diffuse reflection which is predominant as the local scattered angle is situated out of the specular region.Numerical results are compared with those of experimental and theoretical models in several configurations as a function of incident angle,wind speed,wind direction.The comparison of numerical results of other experimental and theoretical models in several configurations shows that the new composite model is robust to give accurate numerical evaluations for the sea surface scattering. 相似文献