Nonlinear vibration analysis of functionally graded beams considering the influences of the rotary inertia of the cross section and neutral surface position

In the paper work, the nonlinear vibration response of functionally graded (FG) Euler–Bernoulli beam resting on elastic foundation is studied. Based on von Kármán’s geometric nonlinearity, the partial differential governing equations describing the nonlinear vibration of FG Euler–Bernoulli beam are derived from Hamilton’s principle and are reduced to an ordinary nonlinear differential equation with quadratic and cubic nonlinear terms via Galerkin’s procedure. Due to unsymmetrical material variation along the thickness of FG beam, the neutral surface concept is proposed to remove the stretching and bending coupling effect and the rotary inertia of the cross section is incorporated to obtain an analytical solution. Numerical results are presented to show the effects of the nonlocal parameters and vibration amplitude on the frequency responses. This results may be useful in design and engineering applications.     

"转柱法测液体粘度"实验中的速度问题

通过理论计算得到了“转柱法测液体粘度”实验中砝码下落达到匀速所需要的时间和运动距离。     

回转窑火焰监视及温度测量系统

本文介绍了采用彩色CCD基于数字图像处理测量回转窑内投影温度场的基本原理、系统组成和数据处理方法。通过对燃烧火焰和烧成熟料图像的量化分析和滤波,得到火焰和熟料的特征值及相应温度场,可为窑炉的自动控制提供真实可靠的依据。该系统已在国内某水泥回转窑企业成功运行。     

固体废物拟稳态连续式热解过程的质能平衡

本文发展了固体废物连续移动床热解实验系统,热解反应器内气、固相表现为相对独立豹柱塞流,据此确定了反应器的设计原则并完成了设计计算.继而以油泥废物为例介绍了该系统的质量和能量平衡计算,系统的质量损失为7.93%～9.15%,略小于国际同等规模装置的误差,通过能量平衡不仅可以确定出油泥热解过程所需净补充热量大小,还可以能源利用回收效率.该实验装置可以视为回转窑、炉排炉等各种垃圾焚烧过程的原型反应器.     

Molybdenum,Platinum, and Tantalum Metal Atomizers or Vaporizers in Analytical Atomic Spectrometry

Abstract

The application of metal (tantalum, molybdenum, and platinum) devices in analytical atomic spectrometry is reviewed in this article. These metal devices have been employed in various analytical atomic spectrometric techniques for more than three decades, mainly as electrothermal atomizers or electrothermal vaporizers, in various physical shapes, such as tubes, platforms, loops, and wires (or coils/filaments). Their application spans from atomic absorption spectrometry (AAS), atomic emission spectrometry (AES) atomic fluorescence spectrometry (AFS), inductively coupled plasma atomic emission spectrometry (ICP‐AES) to inductively coupled plasma mass spectrometry (ICP‐MS). The analytical figures of merit and the practical applications reported for these metal devices are reviewed, and the atomization mechanism on these metal atomizers is briefly summarized, too. In addition, other applications of the metal devices are discussed, including analyte preconcentration by electrodeposition and sequential metal vapor elution analysis (SMVEA). Furthermore, the application of these metals in graphite furnaces encompasses the schemes with the metals in the form of furnace linings, platforms, or impregnated salts.     

Optimal control of a rotary crane

This paper is concerned with the optimal control of a rotary crane, which makes two kinds of motion (rotation and hoisting) at the same time. The optimal control which transfers a load to a desired place as fast as possible and minimizes the swing of the load during the transfer, as well as the swing at the end of transfer, is calculated on the basis of a dynamic model. A new computational technique is employed for computing the optimal control, and several numerical results are presented.The authors wish to thank Professor D. G. Hull and the reviewers for their valuable comments and suggestions.     

一种高精度绝对式光电轴角编码器的照明系统

介绍了一种高精度、高分辨率绝对式光电轴角编码器的照明系统,照明系统采用了非球面光学系统和温度补偿方法。与以往采用白炽灯作为光源的照明系统相比具有体积小,使用寿命长,抗冲击,抗震动强,装调方便,光电转换效率高,利于多头读数等优点。采用这种照明系统的27位绝对式光电轴角编码器测角精度优于0 3″。     

椭球体转动惯量的计算

用分步计算和广义球面坐标变换两种方法对椭球体绕对称轴旋转的转动惯量进行了计算，计算表明，后一种方法简单、实用，在工程实际中有应用价值．     

利用三线摆验证转动惯量的平行轴定理

本巧妙的利用三线摆,提出了验证转动惯量平行轴定理的新方法,并进行了具体的实验验证。     

一种消除弯晶面形扭曲的轴角装置

Laue晶体单色器常用于单色化高能X射线(＞50 keV),通过对其晶片压弯可以实现高能光束聚焦。晶片压弯过程中会不可避免地产生扭曲,从而影响单色器的工作效率。利用波动光学仿真的方法,分析弯晶面形扭曲对Laue晶体单色器性能的影响,并提出一种角位移微调轴角装置,用来消除这种扭曲。该装置基于直梁型柔性铰链,利用叠加原理和对称结构。利用有限元方法分析了该装置的力学性能。分析结果表明,轴角装置的转角范围为±2°时,其转动中心最大偏移为20 μm,实现了角位移分辨率好于1″,动态范围达到10⁴,达到设计目标。