基于隧道效应的纳米级振动检测及补偿

微振动是提高纳米测量精度的主要障碍,为了减小微振动在STM测量中的影响,需要对微振动进行隔离和检测．因此,抗振、隔振及振动补偿技术成为了纳米测量领域的一大分支．设计了基于隧道效应的纳米级振动传感器,该传感器具有很高的灵敏度和分辨力,并用设计的振动传感器进行了纳米级振动检测试验．在隧道状态下．观察隧道间隙对外界微振动的响应情况,并用测量结果实时对STM测量进行补偿．结果表明,基于隧道效应的测振传感器具有很好的响应特性和良好的幅频特性,并且可以进行STM的振动补偿．     

基于多普勒效应的激光微位移测量系统

介绍了一种可进行动态微位移测量的激光微位移测量系统。该系统以多普勒效应为理论基础，以He-Ne激光器为光源，配置了判向变频系统、CCD视频信号的高速动态采集系统、微机处理系统及干涉图像处理软件包等，较传统测量方法其精度、误差、灵敏度及稳定度都有较大提高，并实现了微位移的全自动测量。     

一种MEMS微流量传感器的设计与分析

近年来,用于生物,制药等领域的微量试剂自动化分配技术不断发展,往往需要进行微量快速的液体流量检测.本文设计了一种基于压差原理,通过测量液体流过精密微流量通道产生的压差实现流速快速测量的集成高速微流量传感器,并用MEMS技术进行本体结构和微流体通道的制作.通过理论计算以及传感器静态和动态建模分析,指出了结构尺寸设计原则,为结构设计提供理论依据,保证了传感器微量快速检测性能的实现.最后通过有限元分析软件对流量传感器结构尺寸进行受力和变形分析,并利用集总建模分析方法,对传感器进行动态特性分析.分析表明传感器在最大系统压力下变形和应力符合要求,响应速度可以达到1KHz以上,具有响应时间短,结构紧凑,功耗小的特点,特别适合于高通量自动化微量试剂操作系统中微流量的快速测量.     

环形管流量计测量气液两相流研究

提出了一种基于环形管流量计的新型气液两相流流量测量方法.设计了多圈环形管流量传感器,通过对多圈环形管的水平直径上和垂直直径上四个差压信号进行分析,建立了不同位置差压信号与总体积流量和总质量流量的关系模型,并由此获得气液两相流的混合密度,实现了气液两相流分相流量的测量.     

转子微小流量传感器的研制

介绍了一种新型基于可变面积原理设计的微小流量传感器,阐述了高精度微流量传感器理论设计方法、结构特点,同时也对微流量传感器进行实验验证.实际测量和使用表明:该传感器具有精度高、可靠性高、抗干扰能力强、结构简单、智能化等特点.     

基于法布里-珀罗干涉仪的微位移测量方法研究

介绍了一种基于法布里-珀罗干涉仪的微位移测量方法,通过将位移测量转化为频率变化量的测量,实现了亚纳米级测量分辨力.建立了基于法布里-珀罗干涉仪的微位移测量实验装置,完成了320 nm范围内的位移测量,并将测量结果与精密电容传感器的测量结果进行了比较.     

基于层析成像的气液两相流相关流量测量方法

对电阻层析成像技术和图像的小波纹理特征进行了研究,提出一种基于层析成像的气液两相流相关流量测量方法,实现了液相流量的准确测量。利用电阻层析成像技术和相关算法对不同泡型下的相含率、渡越时间进行检测,得到气相流量;利用小波分析提取出层析成像的流型纹理特征;从而基于BP神经网络建立不同泡型下的气液两相流的相关流量测量模型。实验结果表明,液体流量的测量精度可以达到3%以内。     

关于空气流量计的一些常见故障

<正>一、空气流量计基本结构及性能特点空气计量传感器按测量空气流量的方法可以分为两种:一是直接测量方法传感器——空气流量计。二是间接测量方法传感器——进气歧管压力传感器。直接测量方法传感器按其测量信号转化形式不同又可分为三种。1.机械式空气流量计,即可动叶片式空气流量计。其特点是将燃油     

固定排放源烟气流量在线监测技术

在温室气体减排、环保核查越来越受到政府、民众和媒体关注的大背景下,介绍了固定排放源烟气流量在线监测的基本原理和技术。基于速度面积法的烟道气体流量测量技术关键在于被测截面面积的获取与截面内平均流速的测量。文章着重介绍了应用皮托管和多声道超声流量计测量烟道气体流量的方法,并给出了两种测量方法应用于河南某燃煤电厂进行烟气流量测量的实例,最后对两种方法测量的结果进行了分析和比较,认为皮托管和超声流量计在烟气流量测量中都有着广泛的应用前景。     

基于传热原理的高温蒸汽流量测量研究

提出了一种基于传热原理高温蒸汽流量测量的新方法,分析了测试原理的可行性,并建立了依据该测试原理进行流量测量的实验台。实验结果表明,基于传热原理流量测量方法所依据的测试原理是正确的。由于该流量测量方法将流量测量问题转化为温度测量问题,因此测量误差主要取决于温度测量的准确度。     

城市道路网运行实时动态评价理论和技术研究

从道路网运行的基本特性入手,着重分析了路网运行的随机波动性、递延传导效应和周期规律性。在此基础上,剖析了迄今国内外一直沿用的道路"负荷度"路网评价理论的局限性,提出一套适用于路网整体实时动态评价的理论和技术方法,解决了无盲区实时数据采集与处理、路网运行时空动态分析、评价指标阈值标定等关键技术难题,为交通战略规划、实时动态路网功况诊断等提供了全新的技术手段,北京市的实证研究初步证明了所提出的理论和技术体系科学、有效、实用。     

标准铂电阻温度计自热效应对测量结果的影响

为了研究自热效应对标准铂电阻温度计测量结果的影响,分别从定点法和比较法两方面开展研究.针对定点法,统计中国计量科学研究院近3年检定的标准铂电阻温度计数据,计算不同温区的铂电阻温度计自热效应修正前后的测量结果并进行对比,结果表明,在溯源标准铂电阻温度计时自热效应修正与否对测量结果的影响达到了1.5 mK以上,最大达到了6...     

Hydrodynamic interaction of axial turbomachine cascades

Hydrodynamic interaction of mutually moving airfoil cascades is investigated. It is shown that the semi-empirical theory of potential-vortical interaction of two mutually moving cascades in incompressible flow allows one to describe correctly the features of their mutual effect for various gaps between cascades and relations of their pitches. Application of the above theory to a flow around three cascades of the stator-rotor-stator type allows to determine the basic mechanism of the stators’ mutual shift effects (clocking effects). To close the theory regarding the vortical interaction of cascades, a semi-empirical model of turbulent diffusion in a non-uniform flow of the periodic vortices descending from airfoils is proposed. Theoretical results are compared with data from numerical and physical experiments. Comparison with results of numerical modeling is based on the solution of the Reynolds equations for a viscous gas closed by the (q-ω) model of turbulence. Results published here and elsewhere are used for comparison with measurement data     

科氏流量计气-液两相流的数值模拟

针对科氏流量计在测量含气-液两相的流体时,流量计随着气体含量的增加,测量稳定性逐步变差的问题,采用流固耦合有限元技术,对科氏流量计进行了模态分析和流固耦合振动分析。作为一个实例,使用该方法模拟气泡含量以及分布对测量稳定性的影响,在气泡含量1%左右时测量相对稳定,气泡含量大于5%时测量稳定性很快变差。     

Measurement for optical arbitrary waveforms using cross-phase modulation cross-correlation frequency-resolved optical gating in a single-mode fibre

A novel scheme of cross-correlation frequency-resolved optical gating (X-FROG) measurement for optical arbitrary waveforms based on the photo-elastic effect and cross-phase modulation (XPM) effect in a single-mode fibre is proposed. In this scheme, a variable delay is generated in the former part of the single-mode fibre by a uniform lateral pressure, and the XPM effect is achieved in the latter part of the fibre. The proposed scheme is very simple and easy to be realized. The amplitude and phase of optical arbitrary waveform to be measured is retrieved from the X-FROG trace using principal component generalized projects algorithm based on matrix. The impacts of the shape of gate pulse, fibre length, relative intensity between gate pulse and optical arbitrary waveform and the complexity of the optical arbitrary waveform on the accuracy of retrieved amplitude and phase are investigated. Simulation results show that, rectangular pulse is a better gate pulse due to lower errors. The accuracy of measurement is improved with the increase in fibre length, and relative intensity between gate pulse and optical arbitrary waveform. Moreover, this scheme also can be used to measure extremely complex optical arbitrary waveforms.     

Some Metrological Characteristics of Flow Meters in Which the Coriolis Force Is Used

The effect of the viscosity of the medium being measured is investigated. It is proved that the readings of a flow meter based on the use of the Coriolis force depend on the viscosity of the medium (the velocity profile) and the measurement error may reach 30%. The effect of a change in the parameters of the gas flow on the readings of such flow meters as a function of the location of the instrument (the longitudinal coordinate) is also considered and a conversion formula is derived.     

Measurement of permeability of continuous filament mat glass–fibre reinforcements by saturated radial airflow

The measurement of fibre reinforcement permeability is important for the understanding, optimisation and modelling of RTM and resin infusion processes. This work investigates the use of a saturated radial air flow experiment for measuring the permeability of continuous filament mat (CFM), which is a common reinforcement type used for industrial RTM parts. The use of air, rather than liquid resin, is cleaner, quicker and potentially easier to control. The paper considers the problems inherent in using a compressible fluid, instead of a liquid, for the measurement of permeability, and the requirements for maintaining laminar flow. It describes the instrumentation used for flow and pressure measurement, and the effect of varying flow rate. Results compare favourably with published permeability values based on liquid flow experiments, and are independent of flow rate within the range of values investigated.     

LCM 充模过程中的边缘效应

边缘效应是复合材料液体模塑成型技术(Liquid composites molding , LCM) 中常见的纤维预成型体铺敷缺陷之一。采用单向流动法研究了边缘效应对纤维预成型体渗透率及充模过程的影响, 结合其等效渗透率的理论预测模型对不同纤维体积含量、不同缝隙宽度条件下的边缘效应进行了模拟与分析, 提出了一边缘效应强弱的表征因子, 并以一较复杂的模腔的充模过程为实例提出了对边缘效应的在线监控策略及处理方案。      

Propagation model and error analysis of an E-field sensor based on pockels effect and waveguide

Electric field measurement sensors based on the crystal Pockels effect are widely used. Currently, the development aims for electric field sensors are mainly focused on miniaturizing and integrating the sensor structure and improving measurement sensitivity and precision. The goal of this study was to analyse the sources of error in Pockels effect electric field measurement sensors, consider the mutual influence and accumulation effect of the various error factors, and establish a basic mathematical model of the measurement system with error components. Calculation and analysis were used to classify the function and change trend of several main errors, providing reference data for the structure design and error compensation of the sensor. The results show that the polarizing angle and the analyser angle have the same influence on assembly error. The inherent error is positively related to the electric field intensity. The periodic accumulation characteristic error under large electric field is also discussed. In order to avoid this error under an intense electric field, a suitable test electric field range was determined.