定常的热传导-对流问题的非线性Galerkin/Petrov最小二乘混合元法

In this paper,a nonlinear Galerkin/Petrov-least squares mixed element (NG-PLSME) method for the stationary conduction-convection problems is presented and analyzed.The method is consistent and stable for any combination of dis-crete velocity and pressure spaces without requiring the Babuska-Brezzi stability condition.The existence, uniqueness and convergence (at optimal rate) of the NGPLSME solution is proved in the case of sufficient viscosity (or small data).     

Focal evolution induced by combination of nonspiral and spiral phase plates

Focusing properties of Gaussian beam induced by nonspiral and spiral phase plates are investigated numerically. The nonspiral phase plate introduces phase singularity to the incident beam, and the spiral one adjusts the radial phase distribution. Intensity distributions in geometrical focal plane show that the parameters of phase plates can alter the intensity distributions considerably. And local dark focal spots may be obtained, the focal spot may evolve into a circle, a two-peak spot, or a curve line, which indicates that the combination of nonspiral and spiral phase plates can be used to form novel focal spots.     

Focusing properties of concentric piecewise cylindrical vector beam

The focusing properties of a concentric piecewise cylindrical vector beam is investigated theoretically in this paper. The beam consists of three portions with different and changeable phase retardation and polarization. Numerical simulations show that the evolution of the focal shape is very considerable by changing the radius and polarization rotation angle of each portion of the vector beam. And some interesting focal spots may occur, such as two- or three-peak focus, dark hollow focus, ring focus, and two-ring-peak focus. Corresponding gradient force patterns are also computed, and novel trap patterns, including cup shell shape trap with one trap at its each side along axis, rectangle shell shape trap with one trap at its each side, dumbbell optical trap, spherical shell optical trap, may occur, which shows that the concentric piecewise cylindrical vector beam can be used to construct controllable optical tweezers.     

Prediction of Vapor–Liquid Equilibria for Pb–Pd and Pb–Pt Alloys Using Ab Initio Methods in Vacuum Distillation

The vapor–liquid equilibrium (VLE) phase diagrams of Pb–Pd and Pb–Pt alloy systems in vacuum distillation were obtained based only on pure-component properties and the structures of the atoms. The interaction energies between pairs of atoms were calculated from ab initio methods and were used as the input energy parameters for the Wilson equation. The calculated activity data of the components, using energy parameters which were obtained by ab initio methods, are in good agreement with the experimental data. It is revealed that a cluster size of eight atoms, optimized using the NVT ensemble at 300 K, a time step of 1 femtosecond, and the simulation time 10 ps gives a good representation of the liquid phase systems. This approach can be used to obtain accurate VLE predictions for alloy systems in vacuum distillation. The VLE phase diagram has a significant advantage in guiding experiment and industrial production in vacuum metallurgy.     

Physical layer data encryption using two-level constellation masking in 3D-CAP-PON

A novel physical layer data encryption scheme using two-level constellation masking in three-dimensional(3D)carrier-less amplitude and phase modulation(CAP)passive optical network(PON)is proposed in this Letter.The chaotic sequence generated by Chua’s circuit model realizes two-level encryption of displacement masking and constellation rotation for3 D constellations.We successfully conduct an experiment demonstrating 8.7 Gb/s 3 D-CAP-8 data transmission over25 km standard single-mode fiber.With two-level constellation masking,a key space size of 2.1×1085 is achieved to bring about high security and good encryption performance,suggesting broad application prospects in future short-range secure communications.     

抛物型方程的交替分段Crank-Nicholson格式

本文构造了求解扩散方程的交替分段Crank-Nicolson格式,格式无条件稳定而且有明显的半行性,数值例子说明这个新方法具有满总的计算精度.     

红花罂粟植物的各个部分中蒂巴因含量的测定

采用甲醇浸泡、超声波一次提取处理样品,气相色谱内标法定量测定不同种类及不同培育方法的红花罂粟植物的全果、根、叶、苞片、果盖、果壳、茎中蒂巴因的含量。方法采用多点校正,其线性相关系数为０．９９６,变异系数为２．９％～５．４％,最低绝对检出量可达２ｎｇ。蒂巴因的色谱峰为双峰,经质谱确证为异构体,这两种异构体的比例不固定,取其峰面积之和定量。应用该方法对前后３年共１６８个样品进行了测定,提取样品中蒂巴因的图谱与蒂巴因标准品的图谱完全一致,样品中的其它杂质均不干扰蒂巴因的测定。     

盐酸环丙沙星与胰蛋白酶相互作用的光谱和分子模拟研究

运用荧光光谱和紫外光谱, 结合分子模拟法研究了盐酸环丙沙星(CPFX)与胰蛋白酶(Trypsin)在不同温度条件下(288, 298和308 K)的相互作用. 研究发现CPFX对Trypsin有较强的荧光猝灭作用, 且为静态猝灭类型. 根据双对数方程处理荧光猝灭数据得到了CPFX与Trypsin在不同温度下的结合常数K和结合位点数n. 利用紫外光谱定性讨论了CPFX对Trypsin构象的影响. 通过热力学方程求得了不同温度下CPFX与Trypsin作用的热力学参数, 表明它们之间的作用力主要是疏水作用和氢键, 这与分子模拟方法所得的结果是一致的.     

氧化锰八面体分子筛纳米棒的合成及其催化甲醛低温氧化性能

 Uniform manganese oxide octahedral molecular sieve (OMS-2) nanorods were synthesized by adding a small quantity of K2S2O8 to the solution containing MnSO4·H2O and KMnO4, and used for complete oxidation of formaldehyde. According to the results of N2 adsorption and X-ray diffraction, the material is a manganese oxide octahedral molecular sieve with the cryptomelane type structure. TEM observation shows that the diameters of the nanorods range from 15 to 25 nm, and the lengths are 300～400 nm. Complete conversion of HCHO to CO2 and H2O can be achieved at 353 K over OMS-2, and the same conversion is obtained at 373 K on the MnOx powder under the same conditions, which demonstrates that the catalytic activity is closely related to the morphology of the catalysts.     

色散补偿技术中超短光脉冲传输特性的研究

本文用变分法对色散补偿技术中超短脉冲的传输特性进行了理论和数值分析.首先给出了描述超短脉冲传输特性的耦合微分方程组,然后对其进行数值求解.计算中考虑了光纤非线性系数的差异,首次引入平均非线性系数参量.分析表明,要想达到最佳的传输性能,不同的色散补偿方案,对超短脉冲的入纤能量将有不同的要求.最后给出超短脉冲最佳的入纤能量与其脉宽、色散参量比、光纤长度,以及平均色散参量间的关系图.