Hybrid mesh adaptation applied to industrial numerical combustion

This paper presents an anisotropic mesh adaptation method applied to industrial combustion problems. The method is based on a measure of the distance between two Riemannian metrics called metric non‐conformity. This measure, which can be used to build a cost function to adapt meshes comprising several types of mesh elements, provides the basis for a generic mesh adaptation approach applicable to various types of physical problems governed by partial differential equations. The approach is shown to be applicable to industrial combustion problems, through the specification of a target metric computed as the intersection of several Hessian matrices reconstructed from the main variables of the governing equations. Numerical results show that the approach is cost effective in that it can drastically improve the prediction of temperature and species distributions in the flame region of a combustor while reducing computational cost. The results can be used as a basis for pollutant prediction models. Copyright © 2011 John Wiley & Sons, Ltd.     

A moving mesh algorithm for aero‐thermo‐mechanical modelling in turbomachinery

This paper describes the development of a mesh deformation method used for aero‐thermo‐mechanical coupling of turbo‐engine components. The method is based on the nonlinear solution of an elastic medium analogy, solved using finite element discretisation and modified to let the boundary nodes be free to slide over the deflected surfaces. This sliding technique relies on a B‐spline reconstruction of the moving boundary and increases the robustness of the method in situations where the boundary deflection field presents significant gradients or large relative motion between two distinct boundaries. The performance of the method is illustrated with the application to an interstage cavity of a turbine assembly, subjected to the deformations computed by a coupled thermo‐mechanical analysis of the engine component. Copyright © 2011 John Wiley & Sons, Ltd.     

光纤全息散斑干涉计量

脉冲激光经光导纤维传输后，其偏振性变化为随机分布，相干性有所降低，但它用在全息干涉计量中却有突出的优点，对于涉条纹的形成和清晰度没有影响。经常使用的光纤散斑全息干涉系统有两种类型：一种是只用传光束形成物光，参考光，此种系统形成的全息象清晰度有所下降，但做全息干涉计量时对条纹的衬比度和清晰度没有任何影响．另一种类型是物光和参考光都是用光导纤维传输，然后用光纤传象束将物体的象进行传输，再用透镜将其成象在底片上，做双曝光全息干涉时则形成全息散斑干涉计量，用全息方法再现时干涉图类似“杨氏”条纹。本文对上述两种系统，结合实验结果、分三种情况进行了研究。文章共分为三个部分：（一）引言；（二）散斑全息干涉计量；（三）结论。     

光纤液位传感器检测原理探讨

叙述光纤液位传感器在贮油罐中的应用,提出实验所采用的方案。推导出液面高度公式,比较实现检测的两种电路的优缺点,同时对实验精度和测量范围进行了讨论。     

双折射光纤中克尔效应及光纤－光学逻辑门

本文详细地研究了单模双折射光纤中的克尔效应．讨论了其应用于光纤－光学逻辑门的优点,给出了有关的理论分析和计算结果以实验装置,确定了强度型逻辑门的“１／０”状态,测出了输出光脉冲宽度．理论分析和实验结果符合良好．     

孤子掺杂光纤放大的半径典模型与分析

建立了孤子掺杂光纤放大的半经典模型，给出了分布放大透明传输的泵浦条件，详细讨论了激发态吸收的影响．文中结果为Ｅｒ￣３＋掺杂光纤孤子放大器的设计提供了重要理论依据．     

光学孤子在色散缓变光纤中的传输特性研究

从理论上分析了超短光脉冲在色散缓变光纤中无畸变传输所要求的色散变化关系，设计了单模缓变光纤结构参数。数值模拟验证了理论分析结果，指出改变光纤色散参数完全可以克服光纤损耗对光孤子波形的畸变影响。     

ROBUSTNESS OF AN UPWIND FINITE DIFFERENCE SCHEME FOR SEMILINEAR CONVECTION-DIFFUSION PROBLEMS WITH BOUNDARY TURNING POINTS

We consider a singularly perturbed semilinear convection-diffusion problem with a boundary layer of attractive turning-point type. It is shown that its solution can be decomposed into a regular solution component and a layer component. This decomposi-tion is used to analyse the convergence of an upwinded finite difference scheme on Shishkin meshes.     

Adaptive femtosecond pulse shaping to control supercontinuum generation in a microstructure fiber

Efficient confinement of laser radiation in the core of a photonic crystal fiber increases the nonlinear processes resulting in supercontinuum generation. The technique of adaptive pulse shaping using an evolutionary algorithm provides a method to gain control over such highly nonlinear processes. Adaptive pulse shaping of the driving laser radiation passing through the photonic crystal fiber is employed to modify the shape and composition of the output supercontinuum. Amplitude and phase shaping are used to optimize the broadband emission between 500 and 700 nm, as well as a soliton centered at 935 nm. The intensities of the emission and of the soliton driven by a shaped laser pulse increase in comparison to an unshaped pulse by factors of 4 and 3, respectively. The spectral width in the range of 500-600 nm is increased by approximately 40%. In addition, the suppression of self-steepening effects in supercontinuum spectra is demonstrated.     

A Polarization-Stabilized Fiber-Optical Output Infrared Laser Source

In this paper, we successfully invented a polarization controlled light source for coherent or noncoherent fiber communication systems. The structure of our experiment includes 89C51 control board and feedback circuit which can stabilize states of polarization (SOPs) of output light. From the SOP modulation results, the given degree of polarization can be effectively controlled and the polarization state can be arbitrarily changed.