Finite speed of propagation for thin viscous flows over an inclined plane

In this paper, we consider the fourth-order nonlinear degenerate parabolic equation

h_t+[hⁿ(h_xxx−αh_x+β)]_x=0,     

基于仿射传播的道路网络聚类

对于道路网络聚类问题,提出了仿射传播算法。首先,将道路网络上的交叉路口和结点作为顶点,建立了无向图;然后,根据最短路径计算网络距离,进而得到图的相似度矩阵;并基于仿射传播算法对道路网络进行聚类;最后,试验结果证实了本文方法的有效性与稳定性。     

胶体晶体微结构光纤传输特性研究

介绍了胶体晶体微结构光纤的结构, 采用时域有限差分法研究了微结构胶体晶体光纤的传输特性. 建立了该结构的FDTD模型, 计算了其透射谱和不同波长的传输场分布. 搭建了光学系统, 测量了实验制备的胶体晶体微结构光纤的透射谱, 并将其与模拟所得透射谱进行比较, 具有良好的一致性. 胶体晶体微结构光纤的传输场分布结果表明, 胶体晶体在不同波长下改变光纤传输场分布.     

高斯涡旋光束在自由空间传输中电场和磁场的偏振奇点

利用矢量菲涅尔衍射积分公式, 以高斯涡旋光束为例, 推导出傍轴高斯涡旋光束在自由空间传输过程中电场分量和磁场分量的解析表达式, 详细研究了自由空间中电场和磁场的偏振奇点变化规律. 结果表明, 高斯涡旋光束在自由空间传输中, 存在二维和三维电场和磁场的偏振奇点, 其位置一般不重合. 改变光束束腰宽度比、 振幅比以及传输距离, 偏振奇点出现移动. 在二维电场和磁场中, 当满足一定条件时, 会有V点产生.     

TE-TM模变换型光波导隔离器的理论研究

利用微扰理论研究了TE-TM模转换型光波导隔离器的自相位补偿. 从相位同步和功率转换解释了这种器件的工作原理, 揭示了两个模转换器相位 失配与模转换比例的关系, 数值仿真结果与理论分析相符, 证实了模转换型 波导隔离器中的自相位补偿理论.     

真空脉冲放电金属等离子体生成及传播特性

研究了采用放电电流为200 A,持续时间为13 s的单脉冲放电形式,在锥-板、锥-网两种电极结构下,等离子体生成及空间传播特性并使用探针法对生成等离子体的电子密度、电子温度、空间电位、离子能量等参数进行了测量。实验和仿真结果表明;锥-网电极的起始放电电压较高,生成的等离子密度较大,沿放电电极轴方向运动的等离子体的密度最大。然而,两种不同电极结构生成的等离子体的传播速度没有明显区别。     

高功率激光系统nm宽带激光脉冲传输特性

对高功率激光系统采用宽带激光消除菲涅耳衍射问题进行了研究,指出只有数百nm的宽带啁啾光脉冲才对近场衍射有一定的平滑作用,数nm的宽带啁啾光脉冲对近场衍射几乎没有平滑作用;同时,还对宽带啁啾光的B积分表征方式和最快增长频率问题进行了研究,并与原型装置上开展的窄带脉冲、宽带啁啾堆积脉冲的非线性实验结果进行了对比研究,指出以最大B积分或加权B积分反映非线性自聚焦更为准确。研究还表明,在数nm,ns情况下最快增长频率与窄带激光脉冲的差别不大。     

Analyzing of the effect of the dusty fluid,anisotropy and layered of the wall on the wave propagation

This study considers the propagation of time harmonic waves in, prestressed, anisotropic elastic tubes filled with viscous fluid containing dusty particles. The fluid is assumed to be incompressible and Newtonian. The tube material is considered to be incompressible, anisotropic, and elastic. The tube is subjected to a static inner pressure P_i and an axial stretch λ. Utilizing the theory of “Superposing small deformations on large initial static deformations”, differential equations governing wave propagation inside the tube are obtained in terms of cylindrical coordinates. Analytical solutions for the equations of motion for the dust and the fluid are obtained, and expressed numerically. The dispersion relation is obtained as a function of the stretch, the thickness ratio and the parameters for dusty particles.     

Physical interpretation of the paraxial estimator

The paraxial estimator (PE) is a parameter quantifying the paraxiality of a light beam. Even if some of its features were previously tackled, key details on its behavior were not fully presented. This paper robustly presents the physical meaning of the PE in a global way, enlarging its interpretation out of the paraxial region what permits to get a first view of the beam propagation dynamics from the value of this parameter. The physical interpretation is given in the spatial domain and in the spectral domain as well. In the first one, the value of PE is related to the competition between the fast oscillations and the remaining oscillations of a propagating field. Looking at spectral domain, the PE deals with the spectral dispersion (or width) of the plane waves forming the field. In this context, a negative value of PE concerns the effective contribution of the evanescent waves what only happens in a strong nonparaxial regime. The PE also accounts the geometric and physical features on the concept of the paraxial approximation in a natural way. An analysis performed for beams propagating through a spherical thin lens reveals that the loss of paraxiality is due to the geometric effect of ray bending by the lens and by another physical effect, concerning the nonideal collimation of the beam.