WiFi无线传输的薄膜热电偶温度采集系统设计

为了解决现有丝状热电偶温度数据采集系统的采样频率和传输速率低、传输方式不灵活、不适用于薄膜热电偶的问题，文中设计了一种采用WiFi无线网络作为数据传输方法、提高采样速率并引入非线性补偿方法的K型薄膜热电偶无线温度采集系统。实验结果表明，该系统能够在0～650℃的量程内对K型薄膜热电偶进行瞬态温度测量，最大采样率为100 kHz,温度分辨力为0.16℃,非线性补偿后的测量精度达到0.2级。幅频特性测试结果表明，该系统可对最高频率分量为25 kHz的瞬态温度信号进行测量。     

多路温度测量系统软件设计与应用

详细介绍了多路温度测量系统的基本原理,并从实用的角度分析了运用该系统实现对温度多路循环采样、储存采样温度值和与上位机通信,最终实现人机对话功能.同时对影响控制过程的各种因素进行了分析.该控制系统对实现单片机对温度的控制具有重要的实际意义.     

有源电力滤波器的故障诊断与监测系统设计

针对有源电力滤波器(APF)主电路中的IGBT及其驱动器容易引发开路故障,以及如何利用虚拟仪器技术取代传统的电能质量分析装置对APF进行实时监测等问题,通过对APF中IGBT的开路故障进行分析,设计了其相应的故障诊断硬件电路,同时设计了监控系统中的电网电流信号、APF运行温度采样信号的硬件电路,并分析说明了电路工作原理。设计了一种基于Lab VIEW软件的实时监测系统,通过将采样数据发送到该监测系统,实现了利用上位机对APF运行的实时监测功能。最后进行了对电网电压、谐波电流等信号的实时采样,以及对IGBT开路故障的模拟测试。实验及研究结果表明,该系统能够实现对APF的运行状态进行实时监测,同时能够实现IGBT及其驱动器的故障诊断功能,系统故障诊断精确性高、响应迅速。     

多晶硅薄膜热扩散率的测试结构

目前已经有用桥式结构来测试薄膜的热扩散率,在此基础上把辐射、对流、对衬底的传热等环境影响都考虑进去,使得该模型在使用中更符合实际情况,更有实际意义.利用两根不同长度的梁,以相同的电流对其加热,分析其瞬态特性,即可获得多晶硅薄膜的热扩散率.用有限元分析软件ANSYS进行了模拟分析,分析表明模拟结果与理论结果趋势一致,数值吻合,从而验证了模型建立的正确性,说明该方法能够实现对多晶硅薄膜的测量,且具有较高的测试精确度.     

高分辨力遥感相机视频处理的温度适应性设计

对遥感相机成像电子学系统进行了温度适应性设计,以使其在温度大范围变化时或电路存在局部温差时均能实现高质量成像.分析了成像链路中的温度延时因素,提出了温度适应性设计方案和相关双采样( CDS)位置的初始精密对准方法,并进行了实验验证.该方法将CCD驱动器的输出经分压整形处理后作为双采样信号的时序基准,从而使双采样信号具备...     

基于小波变换与LabVIEW的时栅信号采集分析系统设计

针对时栅信号处理系统存在软件编程复杂、系统研发周期长等问题,搭建了一套基于LabVIEW虚拟仪器平台的时栅信号采集分析系统,通过模块化建模,将信号采集、数据处理、结果显示与保存集成于同一个上位机程序中,由硬件触发方式实现定点采样,并使用小波变换进行降噪处理,以消除原始信号的零位偏移现象。以72对极的磁场式时栅为测试对象,进行了验证工作,结果表明该系统可以在实验转台的转速为8 r/min时实现将整周误差峰峰值降为3.43″的传感器输出采样。     

基于单片机和多传感器的微型风扇驱动系统

防霾口罩的微型风扇驱动系统为优化使用功能,采用STC12C5A60S2单片机作为控制器,由温度、湿度和声音传感器对周围环境进行采样。单片机对采样信号进行软件滤波等信号处理后,据此生成PWM控制信号,TC1508S双通道直流马达驱动器以该PWM信号作为输入实现对微型风扇转速的控制。该系统实现了防霾口罩通风状态随使用者呼吸需求而自适应调节的功能。     

基于正交匹配追踪的周期非均匀采样研究

结合正交匹配追踪算法,提出了一种针对稀疏信号的周期非均匀采样与重构方法。根据周期非均匀采样的系统模型,基于联合子空间理论将采样与重构过程转换为矩阵向量运算;再借助正交匹配追踪算法确定采样数据矩阵中非零元素的位置,并分析了该算法在周期非均匀采样系统中的完整重构条件,通过插值器实现信号完整重构。最后,以多带正弦信号为例验证了可完整重构概率,系统实验证明:对于稀疏信号的采样与重构,该方法满足完整重构条件。     

基于ARM的激光修整超硬磨料砂轮控制系统

针对激光修整超硬磨料砂轮的需要,设计了一种以ARM为控制核心、嵌入式Linux为操作系统的控制系统.系统通过CCD激光位移传感器实时采集超硬磨料砂轮表面的形貌信号;上位机采用LabVIEW软件对采样值进行存储分析,得出用于砂轮修整的基准信号值并回传给下位机;下位机调用应用程序完成基准信号值与采样值的比较,根据比较结果驱动声光调Q YAG激光器脉冲出光,从而实现激光对超硬磨料砂轮的选择性修整.试验结果表明,系统具有良好的实用性.     

基于MG-Y激光器的光纤法珀传感器信号处理系统北大核心CSCD

针对目前光纤法珀传感器腔长解调系统复杂的问题,提出了一种以MG-Y可调谐激光器为扫描光源的光纤法珀传感器信号处理系统。该系统利用FPGA主控芯片驱动MG-Y激光器实现C波段的线性扫描,同时将光谱信号以触发采样的方式转化为电学信号传送到上位机,设计LabVIEW上位机实现傅里叶频率测量法与最小二乘拟合法运算,最终完成传感器腔长的解调。在实验中使用该系统对不同腔长的光纤法珀传感器进行解调运算,并将解调结果与光谱分析仪解调结果进行对比,实验表明二者具有较好的一致性,在不损失精度的情况下实现了解调系统的小型化。     

Analysis of thermal diffusivity of Ti thin film by thermoreflectance and periodic heating technique

Thermal diffusivity of Ti thin film with several hundred nanometers thickness has been measured by means of thermoreflectance (TR) technique and periodic heating using front heating and front detection configuration. Ti thin films were prepared on Si substrates by dc sputtering method. Then thin Mo layers as reflection layers were coated on Ti thin films. Surface of the Mo layer is irradiated by sinusoidally intensity modulated heating laser. Temperature response at the heated area is measured by a probe laser beam with constant intensity, as a TR signal. Phase lag between the phase of TR signal and that of heating laser beam was obtained from 100 kHz to 2.6 MHz. To analyze thermal diffusivity of Ti thin films using the phase lag data, we developed a three-layer analytical model such as Mo coating (100 nm)∕thin film∕semi-infinite substrate. The calculated phase lag using analytical model is in good agreement with the experimental data for the whole frequency range. The thermal diffusivity of two Ti thin films is determined to be 5 × 10(-6) m(2)∕s, which is 53% of the bulk one.     

表面加工多晶硅薄膜热扩散系数在线测试结构

基于目前已有的真空桥式薄膜热扩散系数测试结构和测试方法，综合考虑辐射、对流以及向衬底的传热等因素的影响，从而使得本文设计的测试结构和提取方法更具有实际价值。文中通过分析两个长度不同，但宽度与厚度相同的梁在相同加热电流下的瞬态电阻变化特性，来提取多晶硅薄膜的热扩散系数。同时利用有限元分析软件ANSYS进行了模拟分析，分析表明模拟提取值与理论值较好地吻合，从而验证了模型建立的正确性，说明该方法能够实现对多晶硅薄膜热扩散系数的在线提取，且具有较高的测试精确度。     

各向异性材料光学常数全自动椭偏测仪

本文介绍了一套将光度式旋转检偏器椭偏(RAE)系统同改变环境媒质、改变样品方位角、改变入射角相结合的全部测试过程由计算机控制的椭偏测试系统VMAE。它是通过改变环境媒质、光入射角以及自动改变样品方位角等方法测量多组椭偏参数,得到足够的独立方程,并通过计算机采用三种优化Powell,单纯形,转轴法方法求解多峰值超越方程组以研究光轴垂直、平行于表面的各向异性体、膜材料光学性能。并研制了一套除适用上述方法外还可兼容多波长法、多厚度法等方法的功能全面的模块集成化软件。最后通过比较实验结果与理论值的方法对系统的可靠性进行了验证。     

A travelling photothermal technique employing pyroelectric detection to measure thermal diffusivity of films and coatings

A travelling thermal wave technique employing optical excitation and pyroelectric detection of thermal waves propagating along a material film/coating on a substrate is described. The method enables direct measurement of thermal diffusivity. The technique involves measurement of the phase lag undergone by an optically excited thermal wave as it propagates along the coating. The set up has been automated for convenient and fast data acquisition and analysis. The technique has been adapted to measurement of thermal diffusivity of a commercial paint sample coated on glass and copper substrates. It is found that thermal diffusivity of the coating is independent of the thermal conductivity of the substrate. Dependence of thermal diffusivity on coating thickness shows exponential increase, with value reaching a constant at a characteristic high thickness. Measurements have been carried out on a few other samples with wide variations in thermal diffusivity, and the results compared with available reports or results obtained following other techniques. Analyses of the results show that the technique allows measurement of thermal diffusivity of coatings and films with uncertainties better than ±2.5%.     

Methods for the measurement of thermal conductivity and thermal diffusivity of very thin films and foils

New methods for measuring the thermal conductivity λ, thermal diffusivity a and emissivity ε of very thin electrically conducting and insulating films and foils are described. Measurements are performed at bismuth films and cellulose acetate foils and results are represented. The methods permit measurements even for very small film thicknesses d down to a lower linit of λd ≈ 10⁻⁸ WK⁻¹. In comparison with publications known to us, this is more than one order of magnitude less than the lower limit reached up to now. Therefore, the methods described enable investigations of heat transport even on extreme thin films.     

基于红外测温技术的微波功率器件降温曲线测量系统

为了有效实现对微波功率器件的热特性分析,在瞬态红外设备基础上开发了一套用于获取微波功率器件降温曲线的测量系统。分析了瞬态红外设备的原理,并根据降温曲线测量的需要对设备进行改造,开发了数据采集和处理系统,扩展了原有设备的功能,重新设计了测温流程、数据处理算法和相应的软件系统,实现了对GaN HEMT器件不同工作条件下降温曲线的测量。测量的降温曲线满足现有国际标准JESD51系列的要求,在器件热特性分析方面具有较好的应用前景。     

高精度金属薄膜磁电阻效应测试系统

概述了探针法金属薄膜磁电阻效应测试的原理;分析了探针因子对测量结果的影响;设计组装了金属薄膜磁电阻效应的高精度测试系统,并给出了微机控制软件的关键子程序。该系统集数据采样、数据处理、参数计算等功能于一体,用户界面友好、测试范围宽、精度高。系统软件还能显示和打印测量结果的数据曲线,并可生成标准数据文件供OR IG IN等数据处理软件调用。     

Thermal conductivity measurement of thin films by a dc method

A dc method, which needs no complex numerical calculation and expensive hardware configuration, was developed to measure the cross-plane thermal conductivity of thin films in this paper. Two parallel metallic heaters, which were deposited on different parts of the sample, serve simultaneously as the heaters and temperature sensors during the measurement. A direct current was flowed through the same two metallic strips to heat the thin-film sample. The heating power and the heater's temperature were obtained by a data acquisition device, and the thermal conductivity of thin film was calculated. To verify the validity of the dc method, several SiO(2) films with different thicknesses were deposited on Si wafers, respectively, and their thermal conductivities were measured by both the dc method and 3ω method. The results of two methods are in good agreement within an acceptable error, and they are also inconsistent with some of previously published data.     

Measurement of thermal properties of thin films up to high temperatures--pulsed photothermal radiometry system and Si-B-C-N films

A new arrangement of two-detector pulsed photothermal radiometry measurement system has been developed enabling temperature dependence measurement of thermal properties of thin films up to high temperatures. Only a few methods are available in this temperature range for thin films' thermal properties investigation, but there is a need for their knowledge in the fields of high-temperature electronics and high-speed machining. The present system enables simultaneous determination of the thin film effusivity, thermal conductivity, and volumetric specific heat in the temperature range from room temperature to 600?°C. The samples are placed in a vacuum chamber. The temperatures in the system were verified by an independent measurement and the system was tested on known bulk samples. Advantages and shortcomings of the method when used at higher temperatures and in the vacuum are described and discussed. Furthermore, Si-B-C-N thin films were studied. These amorphous ceramic materials possess an interesting set of mechanical and thermal properties. In particular, the films of the investigated chemical composition exhibit an excellent thermal stability at temperatures of up to 1700?°C. In the studied temperature range, from 20 to 600?°C, the thermal conductivity increased with increasing temperature from 1.72 to 1.89 W m(-1) K(-1) and volumetric specific heat increased from 2.65 to 3.76 × 10(6) J m(-3) K(-1).     

基于LABVIEW的内燃机气道试验台测控系统上位机设计

针对内燃机气道试验台测控系统的需求,借助于虚拟仪器技术设计了基于LABVIEW软件的上位机软件,与下位机通过串口进行通讯,完成上位机和下位机的数据传输,调用下位机寄存器中传感器的数值并进行显示和存储,并向下位机发送气门升程的数值.通过自动发送气门升程参数,使气门升程参数发生连续变化,工况稳定后自动采集传感器数据并记录,...