Third order nonlinear optical characterization using focal shift measurements

We report on third order optical nonlinear experimental characterization using Z-scan method through focal shift measurements of a converging lens. The sample is fixed in front of a lens and is illuminated by a collimated beam. The shift of the geometrical focus in the nonlinear regime using input Gaussian beams is related to the nonlinear induced dephasing owing to a simple linear relation. Numerical calculations based on the Helmholtz wave equation are performed. Good agreement is obtained between experimental and theoretical results.     

纹影技术在直喷式柴油机燃烧过程研究中的应用

本文叙述了作者所设计建立的高速纹影摄影光路系统,给出了利用该系统所拍摄的纹影照片,并通过照片简单分析了柴油机缸内的喷雾和燃烧过程。结果表明,纹影技术是研究发动机缸内空气运动和喷雾燃烧过程的有效手段。     

取代环戊二烯锆、铪络合物光解活泼自由基的ESR研究

本文用自旋捕捉术技与ESR相结合的方法,研究取代环成二烯锆、铪络物(RC₅H₄)₂ZrCl₂(R=H,CH₃,C₃H₇,C₄H₉,C₅H₁₁,C₆H₁₁)及(RC₅H₄)₂HfCl₂(R=CH₃,C₂H₅,C₃H₇)光解的活泼自由基。结果表明,取代环成二烯锆、铪络合物与取代环戊二烯钛结合物光解机理相同,即光解初级过程是M-(RC₅H₄)(M=Ti,Zr,Hf)π键的均裂。其差别在于RCpMCl₂(M=Zr,Hf)可为PBN及ND捕获,并后者的加合物表现出氯核的分裂。     

Pansystems studies in stability,bifurcation and chaos

This paper divides fixed subsets into three kinds, mainly discusses the existence of II-type fixed subset, connects the investigations infixed subsets with the studies in non-linear problems, such as stability, bifurcation, chaos, etc., and proposes a kind of discrete simulation to Liapunov stability and his second method.     

壳聚糖/乙炔黑修饰电极上萘酚异构体的电化学行为及同时测定

制备了壳聚糖/乙炔黑复合修饰电极(CS-AB/GCE),采用SEM和交流阻抗法对其进行表征。并利用循环伏安法(CV)研究了萘酚异构体(α-N和β-N)在该修饰电极上的电化学行为,对实验条件进行了优化。结果表明,在p H 7.0的PBS缓冲液中,α-N和β-N在该修饰电极上均出现一不可逆氧化峰,且在20~200m V/s范围内,其峰电流与扫速呈线性关系,表明电极过程是受吸附控制的不可逆过程。计算了电极过程的部分动力学参数,优化了差分脉冲伏安法(DPV)的实验参数,并对α-N和β-N进行同时测定,发现二者的微分氧化峰电流值与其浓度在2.5×10-6~1.0×10-4mol/L范围内呈良好的线性关系(rα-N=0.996;rβ-N=0.998)。α-N和β-N的检出限(S/N=3)分别为3.4×10-7mol/L和2.4×10-7mol/L。采用该法对实际水样进行检测,得到α-N和β-N的加标回收率分别为96.7%~105.1%和98.8%~103.9%。     

Navier-Stokes方程带Backtracking技巧的两重网格算法

1 引 言考虑二维不可压 Navier-Stokes方程:     

用Monte Carlo模拟方法研究ICP－AES中的物理化学过程 Ⅱ．蒸发过程的模拟和有效质量传输速率的计算

本文讨论用ＭｏｎｔｅＣａｒｌｏ方法模拟ＩＣＰ－ＡＥＳ中蒸发过程的理论依据和基本思想，得到了与发射强度密切相关的有用质量传输速率。     

微光光子数字化摄象机

美国自适应光学联合公司(AOA)在哈佛大学 PAPA 探测器的基础上研制成功的光子数字化编址摄象机是一种具有极高探测灵敏度的光子计数式二维微光摄象机。采用多通道光学编码方法,可对光电倍增管探测到的每一个光电于事件产生相应的(x,y,T)时-空坐标数据,微机采集来自光子摄象机的数据流供实时图象显示和处理。     

Identifying the viscoelastic properties of soft matter from the indentation response of a hard film-soft substrate system

The indentation technique is widely used in measuring the mechanical properties of soft matter at the microscale or nanoscale,but still faces challenges by these unique properties as well as the consequent strong surface adhesion, including the strong nonlinear effect, unclear judgment of the contact point, difficulties in estimating the contact area, and the risk of the indenter piercing the sample. Here we propose a two-step method to solve these problems: lay a hard film on a soft matter, and obtain the viscoelastic properties of this soft matter through the indentation response of this composite structure. We first establish a theoretical indentation model of the hard film-soft substrate system based on the theory of plates, elastic-viscoelastic correspondence principle and Boltzmann superposition principle. To verify the correctness of this method, we measure the mechanical properties of the methyl vinyl silicone rubber(MVSR) covered by a Cu nanofilm. Finally, we test the effectiveness and error sensitivity of this method with the finite element method(FEM). The results show that our method can accurately measure the mechanical properties of soft matter, while effectively circumventing the problems of the traditional indentation technique.     

Three-dimensional mixed convection flow with variable thermal conductivity and frictional heating

In this article,three-dimensional mixed convection flow over an exponentially stretching sheet is investigated.Energy equation is modelled in the presence of viscous dissipation and variable thermal conductivity.Temperature of the sheet is varying exponentially and is chosen in a form that facilitates the similarity transformations to obtain self-similar equations.Resulting nonlinear ordinary differential equations are solved numerically employing the Runge-Kutta shooting method.In order to check the accuracy of the method,these equations are also solved using bvp4c built-in routine in Matlab.Both solutions are in excellent agreement.The effects of physical parameters on the dimensionless velocity field and temperature are demonstrated through various graphs.The novelty of this analysis is the self-similar solution of the threedimensional boundary layer flow in the presence of mixed convection,viscous dissipation and variable thermal conductivity.