10GΩ在片高值电阻溯源实验

为解决在片高值电阻参数的溯源问题,组建了一套可溯源的在片高值电阻测量系统,并提出针对该系统的量值溯源方案,实现了在片高值电阻到常规同轴形式标准高值电阻的溯源。组件的测量系统通过额外的探针和线缆将同轴形式的标准电阻器接口延伸至探针末端,使用在片直通对接线将对应探针短接,形成同轴-在片-同轴形式的测量回路,从而将在片测量值与同轴端测量值联系起来,同时给出了保守的不确定度评估方法。使用组建的测量系统进行在片高值电阻溯源实验,实验数据显示在10GΩ点的相对扩展不确定度为0.3%(k=2)。     

超声波塑料焊接温度测量系统

建立了基于惠普可视化工程环境(HP VEE)的实时温度测量系统来测量超声波塑料焊接的温度;并介绍了 HP VEE 的功能、该温度测量系统的组成和采用该系统进行的超声波焊接 PVC 塑料的温度测量试验. 试验结果表明超声波塑料焊接的焊接区温度具有快速升温和快速降温的特点, 在降温过程中由于焊接压力的作用会出现短暂的温度平台, 也说明该测温系统适用于超声波塑料焊接温度测量.     

快速反射镜系统用光栅测微仪

为了精确控制FSM系统中平面反射镜的偏转角度,研制了专用型光栅测微仪对其进行位置测量,以实现系统的闭环控制.在明确了FSM系统对测微仪应用需求的基础上,根据其技术原理,对光栅测微仪的小型滑轨、标尺光栅图案、指示光栅图案、绝对零位编码、指示光栅移相以及接触探头分别进行了设计与选择.经精密加工、装配、调试后,所得光栅测微仪...     

一种用于高压探头校准的高压快沿脉冲信号产生方法

针对现有快沿脉冲信号幅度不足,无法有效实现高压探头上升时间参数测量的难题,提出了一种高压快沿脉冲信号的产生方法。该方法基于单传输线型脉冲成形原理,使高压脉冲信号在传输线上进行传播,最后在匹配的大功率阻抗上产生一个具有明显顶部特征的矩形波。测试结果表明该矩形波幅度可达2kV,前沿的上升时间小于500ps。通过对两款高压探头上升时间参数进行测量,实验结果验证了该方法产生的高压快沿脉冲信号适用于高压探头上升时间参数的校准。     

坐标测量机对凸轮曲线的测量与拟合及其评价

坐标测量机测量凸轮时,确定工件坐标系是一大难题。文中提出一种方法,可以从凸轮任意位置开始检测。仅测量一次凸轮轮廓,所有的测量数据均用于建立被测凸轮的工件坐标系,并可使测量误差、形位误差对凸轮工件坐标系建立的影响降低至最小程度。此外还提出了一种修正开关式球测头半径的计量学方法。     

Electronic error reduction system for clamp-on probes and measuringcurrent transformers

An original electronic device for compensating ratio and phase-displacement errors, of measuring current transformers and clamp-on probes, is proposed. It is intended for low-frequency applications (power frequency and its harmonic components), where the magnetizing current is the main cause of measuring errors. This system reduces the magnetic flux in the transformer core, reducing in this way the magnetizing current. The proposed system even reduces the influence of the error produced by the variation of the burden connected to the secondary winding. Large values of burden can be used without effects on the transformer measuring errors. This device can be directly applied to conventional current transformers, connecting the device to the secondary terminals. It is not necessary to use any auxiliary winding or auxiliary core, or any modification of those transformers     

Multiple and simultaneous detection of specific bacteria in enriched bacterial communities using a DNA microarray chip with randomly generated genomic DNA probes

A DNA microarray chip for detecting the presence of specific bacterial strains was developed using random genomic probes derived from genomic DNA, i.e., without any sequence information. Thirteen bacteria from different genuses were selected as targets. For the fabrication of the random genomic probes, genomic DNA from pure cultures of each bacterium was fractionated using several pairs of restriction endonucleases. After size fractionation of the genomic DNA fragments, random genomic libraries for each bacterium were constructed. From the library, specific probes were amplified by PCR and the probes were affixed to a slide glass to fabricate the DNA microarray chip. The results from tests with pure and mixed cultures of the bacteria used in the fabrication of the chips showed specific responses and only a small portion of cross-hybridization. This DNA microarray chip was also tested to detect the presence of specific bacteria in mixed populations. In these tests, it was demonstrated that this system provided a fast and specific response to the presence of bacterial species in mixed samples, even in activated sludge samples. This indicates that any DNA microarray chip for the detection of specific bacteria can be fabricated using the same protocols as presented in this study without requiring any genus level sequence information from pure isolates.     

Frequency switching time measurement using digital demodulation

A method for measuring frequency switching time in fast switching frequency synthesizers is described. The fast frequency switching waveform is digitized by an oscilloscope, and the switching transient is recovered by digital demodulation. The method can be used to measure the switching time for any fairly wide frequency steps within the acquisition bandwidth of the digitizing system, and it is insensitive to signal amplitude variations. Some results of measurements on a frequency agile signal simulator are presented     

Current density distribution measurement of negative point-to-planecorona discharge

The current density distribution on the plate electrode of a point-to-plane corona discharge is measured with a computer-controlled measuring system. The measurements are taken by rotating the plate which consist of built-in arrays of orthogonal probes. The current-density distribution can be measured for different separation distances between the point electrode and the plane electrode while the applied high voltage can be varied from the voltage required for the onset of corona discharge to 30 kV. The current-density distribution of a single needle is symmetric around its center point within the accuracy of the measurement system. However, the current-density distribution is radially nonuniform. The computer-controlled measuring system is capable of measuring the current distribution of single point and multipoint electrodes     

Real-time photorefractive interferometer for dynamic phase perturbation by self-interference in LiNbO(3)

We propose a simple real-time system and demonstrate its use for measuring dynamic optical phase perturbation. In this system we used a 0.1-wt. % Fe:LiNbO(3) to record the self-interference grating with incident light. The system is a new kind of real-time holographic interferometer. After rise time in the interferometer, the speed for showing the fringes is as fast as that of dynamic phase perturbations. Characteristics of the interferometer are proposed and examined.     

基于微放电加工元件轮廓测量的探针制造

为了推动微加工和微机械技术的进步，微型零件轮廓和尺度测量方法的发展非常重要．可行方法之一就是使用带微探头的小型三维轮廓测量仪．这种仪器的探头必须针对某个零件的测量，按照最佳外形制造．微放电加工有着极小加工力，可用于各种探头的制造，本研究中用它进行探头加工．用这种方法制造了多种探头，将其装在基于扫瞄隧道显微技术(STM)的小型三维轮廓测量仪上．所制造的探头已被成功地用于各种微元件测量，结果表明此方法可行．     

Calibration of specific absorption rate (SAR) probes in waveguideat 900 MHz

The radiation safety tests for hand-held mobile phones require precise calibration of the small electric field probes used for the measurement of specific absorption rate (SAR) in phantoms simulating the human body. In this study, a calibration system based on a rectangular waveguide was developed for SAR calibrations at 900 MHz. The cross-sectional dimensions of the waveguide are a=190 mm and b=140 mm. The waveguide is loaded with a rectangular liquid slab where the dielectric parameters of the medium simulate human muscle and brain. The precise SAR reference is derived from the temperature rise during a short-term (10-15 s) microwave heating of the lossy slab by measuring with sensitive thermistor-type probes equipped with highly resistive lines. The thermistor probes are calibrated against a calibrated mercury thermometer. To improve the uniformity of the electric field at the calibration position, the thickness of the tissue equivalent slab was varied to adjust the standing wave pattern. This resulted in an almost threefold reduction in the positioning error of the E-field probe. The absolute uncertainty of the calibration is estimated to be ±5% (2σ) not including the uncertainty of the conductivity. The difference between the thermally measured SAR and a value computed with the FDTD method was well within this limit of uncertainty. This kind of closed waveguide system is more compact and requires less microwave power than open field calibration systems. Moreover, no radio-frequency interference is generated     

残留农药的光学检测技术和去噪处理

根据残留农药受到紫外光激发能够发出荧光的机理,研究了一种用于测量残留农药浓度的荧光光纤测量系统.该系统采用脉冲氙灯作为激发光源,光纤探测并传输荧光,电荷耦合器(CCD)作为荧光检测系统的光电转换器件.由于荧光是微弱信号,系统采用微弱信号处理电路对CCD输出信号进行了处理,并且采用相关双采样技术有效地抑制了CCD输出噪声的干扰.用该系统对吡虫啉溶液进行荧光分析,实现了对吡虫啉的快速测定,在5～100μg/L范围内,荧光强度和浓度基本呈线性关系,线性相关系数为0.9959.     

A U-SHAPED FIBER OPTIC PROBE TO STUDY THREE-PHASE FLUIDIZED BEDS

A novel U-shaped fiber optic recently developed for three-phase fluidized beds was applied in the present study for bubble characterization in a cylindrical bed. The static pressure profile along the fluidized bed was measured by a data acquisition system constituted by a pressure transducer, a scani-valve and a microprocessor. Air, water and 335µm glass beads were used as gas, liquid and solid phases respectively. Liquid was evenly distributed by a perforated plate and air was introduced above the distributing plate through four injectors. Single core silica fibers were used to guide the helium-neon laser beams into the fluidized bed. Five U-probes, whose design is based on the difference of refraction indices between the gas and the liquid phases, were used for bubble detection. The detecting probes were located on a measuring window at 53.3 cm from the grid. The design of the measuring window allowed the U-probes to be slid into the fluidized bed at different radial positions. Bubble characteristics such as axial bubble length and bubble velocity were investigated. The influence of fluidization conditions on the hold-ups of gas, solid and liquid was also studied.     

A noncontact temperature measurement method in polymerase chain reaction reactors

A new noncontact method for measuring temperatures of liquids, which is based on the fluorescent probes, is proposed. The method is intended for measuring temperatures of reaction media in reactors of devices for polymerase chain reactions in real time and can be used for determining dynamic temperature parameters.     

A U-SHAPED FIBER OPTIC PROBE TO STUDY THREE-PHASE FLUIDIZED BEDS

A novel U-shaped fiber optic recently developed for three-phase fluidized beds was applied in the present study for bubble characterization in a cylindrical bed. The static pressure profile along the fluidized bed was measured by a data acquisition system constituted by a pressure transducer, a scani-valve and a microprocessor. Air, water and 335µm glass beads were used as gas, liquid and solid phases respectively. Liquid was evenly distributed by a perforated plate and air was introduced above the distributing plate through four injectors. Single core silica fibers were used to guide the helium-neon laser beams into the fluidized bed. Five U-probes, whose design is based on the difference of refraction indices between the gas and the liquid phases, were used for bubble detection. The detecting probes were located on a measuring window at 53.3 cm from the grid. The design of the measuring window allowed the U-probes to be slid into the fluidized bed at different radial positions. Bubble characteristics such as axial bubble length and bubble velocity were investigated. The influence of fluidization conditions on the hold-ups of gas, solid and liquid was also studied.     

基于坐标反推法的偏心轮轴升程测量

采用极坐标测量仪、三坐标测量机等通用型测量仪对偏心轮轴进行坐标测量,其主要配备的都是球形测头,无法直接测得偏心轮轴从动件所对应的升程及升程误差。针对此问题提出了一种基于坐标反推法的偏心轮轴升程测量方法。详细介绍了偏心轮轴的结构、对应不同测头的理论升程计算方法。推导了偏心轮轴表面轮廓点坐标反推平面测头、滚子测头和刀口测头的升程模型公式,利用最小二乘圆圆心和回转中心点确定了偏心圆轮的“桃尖”位置。在一台极坐标测量仪上进行了偏心轮轴测量实验,实验结果表明:基于坐标反推法的升程测量方法是有效的,对应3种测头的坐标反推升程与理论升程的差值分别为0.87, 0.90及0.90μm,基于坐标反推的升程能够更准确反映从动件实际运动规律。     

机载抛弃式温度剖面仪系统设计

抛弃式温度剖面测量系统(Expendable Bathy Thermograph, XBT)是一种可在测量船航行状态下进行海洋温度剖面测量的测量仪器,它具有实时、快速和低成本的特点,广泛地应用于大洋科学考察和海洋物理特性研究.基于时分多址原理设计了机载抛弃式温度剖面测量系统(Airborne Expendable Bathy Thermograph, AXBT),该系统允许8个AXBT浮标同时工作,可以大幅度提高测量效率.给出了AXBT机载单元和AXBT浮标的硬件设计,并根据AXBT浮标温度测量的特点给出了通信时隙分配方案和数据冗余编码方案.最后给出了AXBT系统湖上试验结果,试验结果表明AXBT系统工作稳定可靠.     

Evaluation of Flat Surface Temperature Probes

The objective of this paper is elaboration of elements related to metrological analysis in the field of surface temperature measurement. Surface temperature measurements are applicable in many fields. As examples, safety testing of electrical appliances and a pharmaceutical production line represent case studies for surface temperature measurements. In both cases correctness of the result of the surface temperature has an influence on final product safety and quality and thus conformity with specifications. This paper deals with the differences of flat surface temperature probes in measuring the surface temperature. For the purpose of safety testing of electrical appliances, surface temperature measurements are very important for safety of the user. General requirements are presented in European standards, which support requirements in European directives, e.g., European Low Voltage Directive 2006/95/EC and pharmaceutical requirements, which are introduced in official state legislation. This paper introduces a comparison of temperature measurements of an attached thermocouple on the measured surface and measurement with flat surface temperature probes. As a heat generator, a so called temperature artifact is used. It consists of an aluminum plate with an incorporated electrical heating element with very good temperature stability in the central part. The probes and thermocouple were applied with different forces to the surface in horizontal and vertical positions. The reference temperature was measured by a J-type fine-wire (0.2 mm) thermocouple. Two probes were homemade according to requirements in the European standard EN 60335-2-9/A12, one with a fine-wire (0.2 mm) thermocouple and one with 0.5mm of thermocouple wire diameter. Additional commercially available probes were compared. Differences between probes due to thermal conditions caused by application of the probe were found. Therefore, it can happen that measurements are performed with improper equipment or in an improper way for a particular application. Therefore, knowledge and awareness regarding all facts related to the used measuring equipment are essential to avoid the risk of a wrong decision on safety measures.     

基于LOG-Zernike算子的快速图像测量

图像测量技术,一个很重要的方面就是图像的边缘检测定位,而边缘定位的准确与否又直接影响到测量的精度.常用的检测算法都是像素级的,对测量要求较高的场合无法满足要求.定位速度一直是边缘检测算法的一大瓶颈,本文正是在保证一定精度的前提下,研究了快速图像测量算法,即运用LOG算子先对工件进行快速边缘定位,在此基础上采用zernjke矩法将精度提高到亚像素级.为了得到实际的测量尺寸,应用块规进行了系统标定并进行了一系列测量实验,实验结果表明该方法定位精度接近于Zernike矩法,且算法的运行对间大约在1.5s左右.