Focal shift of three-portion concentric piecewise cylindrical vector beam

Focal shift of a concentric piecewise cylindrical vector beam is investigated by means of vector diffractive theory. A section of the beam consists of three concentric portions. The center circle portion and outer annular portion are radial polarized, and the inner annular portion is generalized polarized. The phase of the inner annular portion is tunable. For certain geometric parameters of the beam, the focal shift occurs and can be adjusted by phase shift and polarized direction of the inner annular portion. For some cases, a three-peak focal pattern may occur, and peaks shift in the same direction, and one local minimum also shifts. For some other cases, a two-peak focal pattern may occur with shifting peaks. The tunable quantitative focal shift is investigated in detail.     

热液体动力扭带清洗动力学及其工程应用

为了解决传统扭带存在自转动力矩弱和传热强化幅度低的问题,研究入口反旋斜齿扭带的动力学理论,方法是将总动力矩分解为虚拟的光滑扭带动力矩和虚拟光滑扭带下的螺旋液流对斜齿的冲推力矩之和,运用动量矩定理分析建立了动力矩计算式．以此式指导结构优化和工程应用,使自转动力矩和传热系数均比传统扭带有了成倍提高,设备总阻力仍然在工程许可范围内,成为可以广泛应用于较低流速下自动清洗防垢与高效强化传热的新元件．     

Radially polarized hollow Gaussian beam with on-axis spiral optical vortex

The focusing properties of radially polarized hollow Gaussian beam (HGB) with on-axis spiral optical vortex are investigated theoretically by vector diffraction theory. The phase wavefront of HGB is the function of radial coordinate. Calculation results show that the focusing properties can be altered considerably by beam order of HGB, topological charge of the on-axis optical vortex, and phase parameter that characterizes the radial phase wavefront distribution. Higher topological charge induces focal evolution from one focal spot to annular focal pattern in transverse direction, while phase parameter can lead to focal shift along optical axis remarkably. In addition, focal shift direction can also be adjusted by changing varying direction of phase parameter.     

全息光栅的制作及光栅常数测定的研究

文章介绍了设计性实验——全息光栅的制作及光栅常数测定实验的设计思想、具体要求、常见问题、解决方案。     

有限级超越整函数的差分多项式的值分布

研究了差分多项式H(z)=POk∑(i=1)a_if(z+c_i)的值分布,其中f是有限级超越整函数,P(f)是,的多项式,κ≥2,ci(i=1,…,k)是互不相同的常数,α_i(i=1,…,κ)是非零常数.得到了H(z)-a和H(z)-α(z)的零点的个数的估计,其中a∈C且α(z)(■0)为小函数.讨论了H(z)的非零有限Borel例外值的不存在性.     

On sums of biquadratic powers with almost equal primes

The Ramanujan Journal - For $$18\le s\le 20,$$ we prove that for any sufficiently large positive integer N satisfying local conditions $$\mathcal N_s$$ the equation $$ N=p_{1}^{4}+p_{2}^{4}+\cdots...     

High quality image-pair-based deblurring method using edge mask and improved residual deconvolution

Optical Review - Image deconvolution problem is a challenging task in the field of image process. Using image pairs could be helpful to provide a better restored image compared with the deblurring...     

带吸收边界条件的声波方程显式差分格式的稳定性分析

１．引言 在进行无界或半无界区域上各种波动方程的数值求解时,需引进入工边界以限制计算范围,在这些边界上应加相应的人工边界条件．这种边界条件应保证所求得的有界区域上的解很好地逼近原来无界区域上的解．对波动方程来说,就是在边界上人工反射应尽可能地小,使之对区域内部解的影响在允许的误差范围以内.因而它们被称为无反射边界条件或吸收边界条件．这种边界条件还应保证所形成的有界区域上的微分方程定解问题是适定的．这也是各种数值方法稳定的必要条件。 近二十多年来,已发展了声波方程的各种类型的吸收边界条件,其中以Ｃｌ…     

手性溶解剂在NMR法测定对映体比率和绝对构型的研究进展

综述了手性溶解剂在NMR法测定对映体比率及绝对构型的研究进展.按照手性溶解剂的结构类型,包括胺、酰胺、羧酸、醇、氨基醇、大环化合物,对手性溶解剂的结构特点与手性识别性能进行了详细的介绍.     

Neuronal avalanches of a self-organized neural network with active-neuron-dominant structure

Neuronal avalanche is a spontaneous neuronal activity which obeys a power-law distribution of population event sizes with an exponent of -3/2. It has been observed in the superficial layers of cortex both in vivo and in vitro. In this paper, we analyze the information transmission of a novel self-organized neural network with active-neuron-dominant structure. Neuronal avalanches can be observed in this network with appropriate input intensity. We find that the process of network learning via spike-timing dependent plasticity dramatically increases the complexity of network structure, which is finally self-organized to be active-neuron-dominant connectivity. Both the entropy of activity patterns and the complexity of their resulting post-synaptic inputs are maximized when the network dynamics are propagated as neuronal avalanches. This emergent topology is beneficial for information transmission with high efficiency and also could be responsible for the large information capacity of this network compared with alternative archetypal networks with different neural connectivity.