基于频域相位共轭技术的交叉相位调制所致失真的复原

理论分析和讨论了基于频域相位共轭技术的交叉相位调制所致信号失真的复原和补偿机理，数值模拟了在交叉相位调制作用下，高斯脉冲在中距相位共轭光纤系统中的传输演化过程.结果表明，频域相位共轭技术能够抑制交叉相位调制对光纤系统中传输信号的损害，复原其所导致的信号失真，并能够同步补偿群速度色散和自相位调制非线性效应所导致的信号失真.合适的初始脉冲时延和初始脉冲啁啾有利于频域相位共轭技术对交叉相位调制所致信号失真的抑制. 关键词： 频域相位共轭 交叉相位调制 色散 自相位调制     

Distributed measurement of birefringence dispersion in polarization-maintaining fibers

A new method to measure the birefringence dispersion in high-birefringence polarization-maintaining fibers is presented using white-light interferometry. By analyzing broadening of low-coherence interferograms obtained in a scanning Michelson interferometer, the birefringence dispersion and its variation along different fiber sections are acquired with high sensitivity and accuracy. Birefringence dispersions of two PANDA fibers at their operation wavelength are measured to be 0.011 ps/(km nm) and 0.018 ps/(km nm), respectively. Distributed measurement capability of the method is also verified experimentally.     

Size distribution measurement for densely binding bubbles via image analysis

For densely binding bubble clusters, conventional image analysis methods are unable to provide an accurate measurement of the bubble size distribution because of the difficulties with clearly identifying the outline edges of individual bubbles. In contrast, the bright centroids of individual bubbles can be distinctly defined and thus accurately measured. By taking this advantage, we developed a new measurement method based on a linear relationship between the bubble radius and the radius of its bright centroid so to avoid the need to identify the bubble outline edges. The linear relationship and method were thoroughly tested for 2D bubble clusters in a highly binding condition and found to be effective and robust for measuring the bubble sizes.     

Time-resolved 3D visualization of air injection in a liquid-saturated refractive-index-matched porous medium

The main goal of this work is to implement and validate a visualization method with a given temporal/spatial resolution to obtain the dynamic three-dimensional (3D) structure of an air plume injected into a deformable liquid-saturated porous medium. The air plume develops via continuous air injection through an orifice at the bottom of a loose packing of crushed silica grains. The packing is saturated by a glycerin-water solution having the same refractive index and placed in a rectangular glass container. By using high-speed image acquisition through laser scanning, the dynamic air plume is recorded by sequential tomographic imaging. Due to the overlap between adjacent laser sheets and the light reflection, air bubbles are multiply exposed in the imaging along the scanning direction. Four image processing methods are presented for the removal of these redundant pixels arising from multiple exposure. The respective results are discussed by comparing the reconstructed air plume volume with the injected one and by evaluating the morphological consistency of the obtained air plume. After processing, a 3D dynamic air flow pattern can be obtained, allowing a quantitative analysis of the air flow dynamics on pore-scale. In the present experimental configuration, the temporal resolution is 0.1 s and the spatial resolution is 0.17 mm in plane and about 1 mm out of plane of the laser sheet.     

Emergency response to disaster-struck scale-free network with redundant systems

Disasters cause tremendous damage every year. In this paper, we have specifically studied emergency response to disaster-struck scale-free networks when some nodes in the network have redundant systems. If one node collapses, its redundant system will substitute it to work for a period of time. In the first part, according to the network structure, several redundant strategies have been formulated, and then our studies focused on their effectiveness by means of simulation. Results show that the strategy based on total degrees is the most effective one. However, many nodes still collapse in the end if redundant systems do not have sufficient capability, so emergency responses are necessary. Several emergent strategies controlling the distribution of external resources have been proposed in the second part. The effectiveness of those emergent strategies are then studied from three aspects, such as the effect of strategies on spreading processes, minimum sufficient quantities of external resources and determination of the most appropriate emergent strategy. In addition, the effects of redundant intensity on these aspects have been discussed as well.     

深紫外双层金属光栅偏振器的设计与分析

193 nm波长浸没式步进扫描投影光刻机是实现45 nm及以下技术节点集成电路制造的核心装备.增大数值孔径是提高光刻分辨率的有效途径,而大数值孔径曝光系统的偏振性能严重影响光刻成像质量.光刻机曝光系统偏振参数的高精度检测是对其进行有效调控的前提.基于光栅的偏振检测技术能实现浸没式光刻机偏振检测装置的小型化,满足其快速、...     

High-Resolution Temporo-Ensemble PIV to Resolve Pore-Scale Flow in 3D-Printed Fractured Porous Media

Transport in Porous Media - Fractures are conduits that can enable fast advective transfer of (fluid, solute, reactant, particle, etc.) mass and energy. Such fast transfer can significantly affect...     

Effects of container geometry on granular segregation pattern

In a set of vibrating quasi-two-dimensional containers with the right-hand sidewall bent inward, three new segregation patterns have been identified experimentally including a Two-Side segregation Pattern, a Left-hand Side segregation Pattern and a pattern where big particles aggregate to the upper left part of the container. In a container with small bending degree, either the two-side segregation pattern or the left-hand side segregation pattern is stable, which is determined by the initial distribution of particles.     

中国毛虾流感病毒神经氨酸酶抑制活性肽的研究

以中国毛虾为原料, 以抑制流感病毒神经氨酸酶(NA)活性为初筛指标, 通过控制酶切位点制备了具有抑制NA活性的酶解液. 利用凝胶层析和高效液相色谱等技术分离纯化出高活性的抑制肽, 其IC₅₀ 值为96.1 μmol/L.经串联质谱测定该抑制肽序列为EISYIHAEAYRRGELK, 紫外光谱分析结果证明该抑制肽能与NA结合.基于反向对接, 应用SYBYL软件模拟抑制肽与NA活性区域结合, 确定了抑制肽与NA的结合位点. 细胞毒性实验测得该抑制肽对细胞的最大无毒浓度(TC₀)为1.26 mg/mL.在红细胞凝集实验中, 随着抑制肽浓度增大, 病毒的凝集价显著降低, 证明抑制肽的抗病毒作用具有多靶点.     

大气湍流对斜程传输准单色高斯-谢尔光束空间相干性的影响

由湍流大气中斜程传输时准单色高斯-谢尔(GSM)光束互相干函数的解析式导出了该光束的复相干度.然后,利用表征光束空间相干性的横向相干长度,研究了斜程传输时大气湍流对准单色GSM光束空间相干性的影响.研究结果表明：1)当传输路径偏离水平方向较大(即θ≤88°)时,准单色GSM光束横向相干长度随传输距离均为先迅速增加,后缓慢增加,最后基本保持不变.2)当传输路径接近水平方向(即θ≥89°)时,准单色GSM光束横向相干长度随传输距离均为先增大,达到一个最大值后开始下降并持续减小.3) 关键词： 大气光学 空间相干性 高斯-谢尔光束 斜程传输