扭转振动与纵振动的比较

本文首先推导出了扭转振动的声传输线方程，并从应力和力矩方程，变截面杆波动方程、声传输线方程、指数型和阶梯型半波长谐振杆等方面，对扭振型和纵振型进行了比较。发现：描述两者的基本概念、方程等具有可类比性，但具体到设计杆件时，两者并不具有类比性。     

防止手传振动危害的综合对策

一、概述 自从1911年意大利的Loriga.G发现使用气动工具的工人出现白指现象以来,国外对手传振动危害的调查、振动病的诊断、测试评价、减振措施的研究及应用推广方面都取得了很大的进展。据日本、苏联、美国、英国、法国、加拿大、芬兰、瑞典、捷克等国家的资料看来,各国都是从操作者与工具构成的人机系统来考虑     

低频振动信号数据处理系统的研究

本文介绍了一种新近研究开发的低频振动信号数据处理系统，它具有精度高，实时测量、分析、取得结果、不需后期处理，且采用了数理统计原理，使测量和分析更贴近实际状态。系统中的放大器部分，由于采用单片机控制，一改传统放大器模式，解决了自动调零、自动增益调整、自动放大倍数定标等一系列问题，从而为真正的多点测量创造了条件。系统的十六通道数为一个测点三个方向提供了同时可测量的五个测点和一个备用通道。十五路信息同时     

关于全身振动卫生标准的探讨

目前我国对于全身振动卫生标准乃参照ＩＳＯ２６３１执行，而常用的测振仪器一般能测量计权振动级，对此如何参照？本文探讨了其对应关系，得到８小时振动暴露的疲劳—工效降低限相当于Ｚ振级１１０ｄＢ，Ｘ、Ｙ振级１０７ｄＢ。不同暴露时间不适用时间减半提高３ｄＢ的原则，本文得出了各暴露时间下每种界限对应的振动级。     

关于振动控制的一些基本概念

振动问题是历来就有的,只是目前,越来越引起人们注意罢了。这一方面是由于机器越来越多,功率越来越大,转速不断提高以及结构不断轻型化,以致引起振动的可能性越来越大;另一方面是由于高级、精密、对振动极其敏感的设备、器具越来越多,以及人们对于安静的环境、舒适的生活、条件要求越来越高,因此振动的危害也越来越引起人们的高度重视。所以振动问题是客观存在的事实,不是人们杜撰、臆想出来的。事实上,随着工业建设的发展,以及人们对环境条件要求的提高,过     

振动测试技术讲座（连载）

第五讲数字信号分析仪的原理与使用(一) 数字信号分析仪(简称分析仪)是基于快速傅里叶变换方法和计算机技术产生的,经过多年发展,它已在分析设备中独占鳌头,几乎淘汰了所有模拟式分析仪,它还做到了一机多用(几合一),除分析部分外还有内装信号源、供传感器(如ICP)或传声器使用的放大器、磁盘驱动器、热打印机等;成为振动测试中不可缺少的重要一环。目前分析仪功能愈来愈丰富,指标愈来愈先进,而价格却逐     

中国爆破振动控制技术的新进展

总结了近年来爆破振动波的传播和衰减规律、减振控制方法和远程实时爆破振动测试技术方面的最新研究成果,介绍了基于单孔爆破振动基波的叠加组合预测模型,探讨了人性化爆破振动安全评价标准,对电子雷管精确延迟实现干扰降振的科学研究和经验进行了总结,全面反映了爆破振动安全控制的最新成果.     

车削加工的振动与控制

在机械加工中产生的振动大都属于受迫振动或自激振动,与工艺系统的动态特性有关。本文详细分析了车削振动的主要类型及产生的原因、及其危害,并从刀具、夹具、切削工艺几方面提出了消除振动的建议及措施。     

齿轮箱振动测试与分析

在对某型齿轮箱的模态、振动烈度和振动加速度进行测试的基础上，详细分析了测试结果．模态测试得到了齿轮箱的振型和模态参数，振动烈度测试结果表明该齿轮箱处于良好工作状态，振动加速度测试结果显示该齿轮箱的减振措施达到了预期的效果．最后，对测试提出了建议．     

爆破振动对古建筑物影响测试和分析方法的研究

对古建筑进行震害预测一般采用单体理论分析方法,需要以结构物比较详尽的基础资料为依据.结合一起为保护国家级古建筑(石塔)进行的爆破振动测试,通过实验、归纳分析以及对古塔结构反应的分析,利用加速度和速度值控制,从而更科学地预测爆破施工对古石塔的振动影响.此方法可为那些没有原始图纸资料的古建筑震害预测和保护提供很好的借鉴.     

Limitations of interferometry due to the flicker noise of laser diodes

Interferometry with laser diodes is a cost-effective way to perform displacement measurement. The tunability of laser diodes is also of great interest in multiple-wavelength interferometry. However, the additional flicker noise in the frequency-noise spectrum of semiconductor lasers may become a limiting factor. Investigations on the limitations due to the 1/f noise of laser diodes are presented for both classical and multiple-wavelength interferometry. Measurements at the limit of the coherence length of laser diodes with the corresponding phase fluctuations are reported. The theoretical results are verified experimentally.     

Temperature-dependent refractive index measurements of wafer-shaped InAs and InSb

An experimental method is introduced to measure the refractive index and its temperature dependence for wafer-shaped infrared materials over a continuous temperature range. Using a combination of Michelson interferometry, Fabry-Perot interferometry, and a temperature-controlled cryostat in a laser micrometer, refractive index values and their temperature coefficients can be measured for any specific temperature within a desired temperature range. Measurements are reported for InAs and InSb for a laser wavelength of 10.59 microm.     

高加速度超精密激光外差干涉测量模型

为了精确地描述激光外差干涉在高加速度超精密测量中加速度对位移测量精度的影响机理与规律,建立了高加速度超精密激光外差干涉位移测量模型.通过分析测量棱镜三维运动对多普勒频移的影响,推导出高加速度激光外差干涉位移测量模型.理论分析和仿真实验表明,当测量加速度为9m/s2,匀加速运行的位移为500mm时,由于加速度变化引起的相对论性效应对测量精度的影响为5nm.高加速度超精密激光外差干涉位移测量模型的建立,可提高激光外差干涉在高加速度超精密测量中的测量精度,为激光外差干涉在高速和超高速测量领域的应用提供了理论依据.     

绝对距离测量技术综述

本文从非相干测量和干涉测量两方面综述了绝对距离测量技术方法。重点介绍了干涉测量法中的半导体激光调频干涉测量技术在绝对距离测量中的一些新应用和新方法。     

Shearing interferometer based on second-harmonic generation and a novel technique of n(2) direct measurements

We present a new wave-front sensitive interferometry technique (called dispersion shearing interferometry) for the measurement of both the sign and the magnitude of n(2). The interference pattern is produced by two laterally shifted second harmonics of the laser source. Only the fundamental wave passes through the nonlinear sample, which is placed before the interferometer. We demonstrate this technique on an aggregated colloidal silver solution using a YAG:Nd laser and KTiOPO(4) frequency doublers.     

Measurement of temperature using speckle shearing interferometry

A laser speckle shearing interferometric technique is used for measuring the temperature profile inside a gaseous flame. The experimental results are compared with the values obtained by a thermocouple and also by speckle photography. Good agreement is seen among the temperatures measured by speckle shearing interferometry, speckle photography, and the thermocouple. Speckle shearing interferometry is easier to implement than speckle photography. This is because in speckle shearing interferometry the accurate positions of the fringes can be known without point-by-point analysis and correction for the halo effect.     

Enhanced flow visualization with near-resonant holographic interferometry

Holographic interferometry measurements have been performed on high-speed, high-temperature gas flows with a laser output tuned near a resonant sodium transition. The technique allows the detection and quantification of the sodium concentration in the flow. By controlling the laser detuning and seeded sodium concentration, we performed flow visualization in low-density flows that are not normally detectable with standard interferometry. The technique was also successfully used to estimate the temperature in the boundary layer of the flow over a flat plate.     

Analytical model of Doppler spectra of coherent light backscattered from rotating cones and cylinders

The interaction between a rotating object and laser beams has been studied in the field of laser Doppler velocimetry, where two incident laser beams are focused on one small spot of the rotating surface and interferometry is used. In the case of a single incident laser beam illuminating a relatively large area of the rotating surface, both the Doppler broadening and the reflected-power level are dictated by points distributed over a wide curved area at varying angles of incidence. An analytical model of spectra in backscatter from cones and cylinders rotating around their axes is presented. This analytical solution may contribute to laser Doppler velocimetry as well as ladar applications.     

Experimental comparison of autodyne and heterodyne laser interferometry using an Nd:YVO₄ microchip laser

Using an Nd:YVO? microchip laser with a relaxation frequency in the megahertz range, we have experimentally compared a heterodyne interferometer based on a Michelson configuration with an autodyne interferometer based on the laser optical feedback imaging (LOFI) method regarding their signal-to-noise ratios. In the heterodyne configuration, the beating between the reference beam and the signal beam is realized outside the laser cavity, while in the autodyne configuration, the wave beating takes place inside the laser cavity, and the relaxation oscillations of the laser intensity then play an important part. For a given laser output power, object under investigation, and detection noise level, we have determined the amplification gain of the LOFI interferometer compared to the heterodyne interferometer. LOFI interferometry is demonstrated to show higher performance than heterodyne interferometry for a wide range of laser powers and detection levels of noise. The experimental results are in good agreement with the theoretical predictions.