Rotationally tunable two-beam interferometer with a fixed photosensitive element. Part I. Interferometer based on a beam-splitter cube

A two-beam interferometer based on a beam-splitter cube with a fixed photosensitive element is proposed. The interferometer is designed for generating interference patterns with a tunable period. The only type of motion resulting in a change in the period is interferometer rotation with respect to the source of the light beam. The greatest width of the range of convergence angle tuning is close to 50°, and possible values of this angle lie in the interval from 10 to 180°. The interferometer arms have identical lengths owing to its symmetry. The absence of adjustment elements ensures high stability of the instrument with respect to vibrations.     

基于双通道M-Z干涉仪的FBG光开关研究

为降低电光开光的插入损耗并提高性能,提出了一种基于双通道可调谐马赫-曾德(M-Z)干涉仪制作的光纤布拉格光栅(fiber Bragg grating,简称FBG)光开关,通过改变干涉仪中的可调电动光纤延迟线的延迟时间,实现滤波谱周期的可调谐。通过改变干涉仪其中一臂的延迟时间设定,该光开关能够实现对设定波长光波的开关功能。对光纤M-Z干涉滤波原理进行了理论分析,使用C波段宽带放大自发辐射光源对双通道可调M-Z干涉仪的性能进行了测试。结果表明,其可实现大范围及高精度的滤波调节功能。对基于双通道可调谐马赫-曾德干涉仪制作的FBG光开关,通过FBG开关性能检测系统实验,得到该光开关在波长为1 550nm处的输出光谱,光开关的消光比达到25dB。结果表明,该光开关能够实现大范围高精度滤波功能,具有高消光比、结构简单和易于调节等优点。     

一种大口径电磁流量计的单位元标定方法

针对传统大口径电磁流量计实流标定成本高的问题,提出用小测量管作为单位元的低成本标定方法。以微元理论为基础,将整个流量计测量区域划分成若干个轴向子空间,用小测量管逐个测量各个子空间的感应电动势,提取其有效特性信息,重构后得到整个流量计空间的特性分布,有效解决实流标定带来的成本过高问题,为大口径电磁流量计的低成本标定提供一种有效的方法。重点对零点漂移下小测量管的感应电动势、装置系数和仪表系数的关系进行研究分析,并给出标定系数的最终表达式。用实流标定法和单位元标定法进行简单的标定比对试验,结果表明单位元标定法的准确度等级为0.5级,具有一定的可行性。     

A Scanning System for the Michelson Interferometer with a Linear Motor Based on a Permanent Magnet

A scanning system for the moving mirror of the Michelson interferometer is described. The system is based on a linear motor with a ring-shaped permanent magnet. The operating velocity of the mirror is about 4 cm/s; the shift from the equilibrium position, ±2.5 mm. A mathematical model of the control system is discussed. The electrical schematic circuit of the control unit and tests results of the control system are described.     

基于横观各向同性假定的固定结合部本构关系及有限元模型

提出了一种固定结合部的有限元建模方法。该方法将接触层等效成均质、虚拟的横观各向同性材料。根据结合面的变形和载荷关系,推导了虚拟材料本构矩阵中5个独立变量与法向应力之间的非线性关系。将这个本构关系引入到有限元分析中用以建立机器的固定联接面模型。分析结果与试验结果的对比证实了该方法的有效性。     

基于有限单元法的方形固支平膜片优化设计

针对方形平膜片在传统设计中存在的计算繁琐、效率低下和精度不高等缺陷,应用大型有限元分析软件ANSYS12.0建立了方形平膜片有限元模型,研究了主要结构参数和载荷对弹性特性的影响规律.同时对方形平膜片的优化设计参数进行了分析,并利用软件ANSYS 12.0的优化设计模块对方形平膜片的主要参数进行了优化设计,分析表明优化后...     

基于响应面法的薄壁件铣削参数有限元优化

铝镁合金薄壁结构件在航空工业中广泛应用,但在其加工过程中常因为刚度不足而引起变形。针对上述问题,提出一种基于响应面法的铣削加工参数有限元仿真方法,可有效控制变形及加工质量。对圆柱螺旋立铣刀的铣削加工过程建立刀具平均切削力模型,并将该模型应用于有限元仿真试验。通过对Box-Behnken法设计的四因素三水平试验结果进行分析,探讨了切削速度、切削深度、切削宽度和每齿进给量等4个因素与切削变形的关系。同时,以工程中的典型薄壁结构件为例,优化了该类薄壁结构件的铣削参数,经有限元仿真验证,该优化方法能够有效控制铣削过程的变形。     

基于有限元法的细长薄壁件车削过程的振动分析

某细长薄壁件在车削加工过程中经常出现振动过大,导致加工误差大的现象。针对此种现象,应用有限元软件对其加工过程进行振动模态分析,得出其振动频率和振型,并结合其加工环境进行分析,找到了激振源,并提出了相应改进建议。     

薄壁结构件铣削参数有限元正交优势分析及优化

大型整体薄壁结构件在航空、航天工业中得到了广泛应用。但由于其刚性差,在铣削加工过程中常常出现铣削力过大而引起较大的变形,严重影响工件的加工质量和精度。针对上述问题,提出一种有限元正交优势分析方法,用以优化铣削参数,减小铣削产生的零件变形。该方法采用正交试验设计规划指导有限元铣削加工变形分析的参数方案设计,通过不同方案的计算结果研究分析铣削速度、铣削深度、铣削宽度、每齿进给量对加工变形的影响,得到各铣削要素选择的较好水平;采用优势分析方法对正交试验结果进行处理,得到各铣削要素对加工变形的贡献率,从而确定优化的铣削加工方案。以某薄壁框类零件为例得到了铣削参数的优化组合,经过验证,优化后的试验方案减少了铣削产生的最大变形量,证明了该方法的可行性及有效性。     

基于MSC．NASTRAN的复合材料机翼有限元分析

通过有限元分析软件MSC．NATRAN,建立了复合材料机翼的有限元模型。针对所设计的飞机机翼在气动载荷作用下进行了强度分析,给出了主要构件的应力、应变结果,证明了这种复合材料设计是合理可行的,为复合材料在飞机上的应用提供了参考。     

薄壁半球壳零件拉深成形的有限元模拟分析

通过改变凹模圆角半径、压边力等成形参数对0.5 mm厚铝合金板拉深成半球形零件的成形过程进行了仿真模拟,研究了不同成形参数下零件成形过程中的应力应变分布和零件成形后的壁厚分布,揭示成形参数对半球形零件成形质量的影响.为实际生产中提高半球形零件的成形质量和抑制成形过程中板料起皱与开裂提供了一定的参考.     

Lattice-resolution contrast from a focused coherent electron probe. Part II

In the previous paper, boundary conditions matching the probe to the crystal wave function in scanning transmission electron microscopy were applied by matching the whole wave function across the boundary. It is shown here how that approach relates to previous Bloch wave formulations using (phase-linked) plane wave boundary conditions for wave vectors implied by the range of transverse momentum components in the incident probe. Matching the whole wave function across the boundary, and including a suitably fine mesh in the reciprocal space associated with the crystal to allow matching of transverse momentum components within the probe, leads to a structure matrix A containing many elements which would normally be excluded for plane wave incidence. For perfect crystals, the A-matrix may be block diagonalised. This leads to a considerable increase in the computational efficiency of the model and yields important insights into the physics of convergent probes in perfect crystals-reciprocity in coherent imaging and the small aperture limit for coherent and incoherent contrast are considered. The numerical equivalence of the incoherent lattice contrast calculated in this Bloch wave method and the multislice method using mixed dynamic form factors will be demonstrated. Comparison between both these methods and the frozen phonon model, a prevalent multislice method for annular dark field simulation which has the theoretical advantage of handling double channelling, will be made.     

基于神经网络和有限元法的“V”型件翻边成形性能研究

翻边是一种重要的金属成形工艺 ,曲面翻边的成形性能与几何尺寸及材料参数等因素有很大关系。本文将有限元模拟与人工智能相结合 ,建立了基于改进的BP神经网络的“V”型件翻边成形性能与几何尺寸及材料参数关系的数学模型。与单纯采用有限元法相比 ,该模型具有计算时间短和易使用的优点。与数值模拟和实验结果的比较证实了本模型的有效性。     

基于SolidWorksSimulation的电主轴单元实验平台回转结合部有限元分析

在建立电主轴实验平台虚拟样机模型的基础上,通过SolidWorks、Simulation软件对电主轴单元实验平台回转结合部进行有限元分析．为电主辐单元实验平台的优化设计分析提供参考。     

基于固定频率变化分析的火电机组大型立式循环水泵基础检测方法研究

目前国内大型火力发电机组循环水泵主流配置为两台立式混流泵,泵组功率和质量都较大.1000 MW超超临界火电机组的循环水泵普遍采用两台直径2600 mm的立式混流泵,配套的电机功率一般在6000 kW.泵组连同电机的总重量一般都超过120 t.在我国,前期投产的1000 MW火电机组普遍采用进口泵.泵的基础预埋件一般采用...     

基于ANSYS某车体的有限元模态分析

简述了有限元模态分析的基本理论,建立了某车身的有限元模型,并对其进行了模态分析,得到了车体的特征模型和固有频率.这对车身的结构改进及其安全性、稳定性、舒适性的提高,提供了依据.     

Generalized study of crank-rocker mechanisms driven by a d.c. motor Part II. Applications

Simulation studies are performed for two different 4-bar mechanisms using separately-excited d.c. motors for actuation. The dynamic time-response analyses are carried out by means of numerical solution of the governing state equations on a digital computer. The influence of system parameters, including both motor properties and mechanism properties, on various performance characteristics is investigated, and the results are presented in the form of nondimensional graphs. These graphs help in understanding the interaction between the mechanism and its d.c. drive and are a start at obtaining generalized, quantitative information for the design of actuator-mechanism systems.     

基于CosMosexpress典型零件的有限元分析初探

有限元法是以电子计算机作为计算工具的电算方法。它是对大型复杂结构进行分析的有力工具。CosMosWorks是与Solidworks一同宣布升级的一个独立的分析软件包,它能与Solidworks进行无缝隙整合,我们现在能够在CosMosxpress上进行最开始的分析,然后立即切换到CosMosorks进行更高级的分析。笔者利用小胶辊的有限元分析过程,对CosMosWorks的有限元分析法作了一次尝试。     

A Dispersion Interferometer Based on a CO<Subscript>2</Subscript> Laser

A double-pass dispersion interferometer based on a 9.6-μm CO₂ laser with a sensitivity of 〈 n _e l〉_min ∼ 1 × 10¹³ cm⁻² and a temporal resolution of ∼50 μ s, designed to measure linear plasma density, is described. A ZnGeP₂ nonlinear crystal is used as the frequency doubler. The main advantages of the interferometer are its compactness and a low sensitivity to vibrations of optical elements. The interferometer requires no special vibration isolation. Its main components are arranged compactly on an optical bench outside the apparatus, except for a window for radiation injection and a retroreflector; these are mounted on the wall of the experimental facility's vacuum chamber. The advantages of the dispersion interferometer have been demonstrated in an experiment with a gas-dynamic trap. __________ Translated from Pribory i Tekhnika Eksperimenta, No. 5, 2005, pp. 96–106. Original Russian Text Copyright ? 2005 by Solomakhin, Bagryanskii, Voskoboinikov, Zubarev, Kvashnin, Lizunov, Maksimov, Khil'chenko.