在线超声波流量监测系统设计及其应用

为解决地源热泵系统中的进出水流量测量,设计研究基于超声波时差法原理的非接触式在线流量监测装置。系统以STM32F407 ZE为主控制器,定时采集流量、完成数据封包、加密和远端服务器交互任务;以MSP430F2618为流量测量控制器,采用时差法以TDC-GP22精准测量超声波在介质中传播时间,实现管道流体流速、流量实时监测。系统测试结果实现流量数据测量及上传存储到远端服务器,满足地源热泵系统流量监测需求。     

高精度嵌入式超声波测距系统的研究

为了提高超声波测距精度,分析了超声波测距的原理,针对影响超声波测距精度的主要因素——环境温度,回波时间,从软件和硬件上提出了解决方法。软件上通过进行修正不同温度下的传播速度以达到消除温度对测距精度影响的效果;硬件上设计升压驱动发射电路、由仪表放大器组成的信号幅度补偿电路和双比较器构成的回波检测电路以改善提高超声波质量和更好确定传播时间。经验证,该系统能够实现较高精度的测距。     

基于AVR单片机的超声波测距系统构建

为了提高超声波测距精度,构建了基于AVR单片机的测距及数据处理系统。分析了超声波测距的原理,以AVR单片机为处理器设计了超声波产生和发射电路、超声波接收和信号处理电路以及温度测量和补偿电路等。针对温度对超声波速度的影响,根据超声波速度与温度的关系,设计了超声波速度补偿算法。为了提高回波时间测量准确性,减小随机噪声及空气中其他杂散播干扰的影响,采用均值数字滤波方法,对计数时间进行处理。实测结果表明,在3cm~400cm范围内,超声波测距系统测量数据准确,最大误差为0.66cm。     

单片机控制的高阻测量系统

针对传统高电阻测量实验系统中电容放电时间测量不准的不足,设计与开发出了基于单片机控制的智能开关控制器,其能对实验系统中的电容冲放电时间进行精准的控制,从而提高了实验精度.本文详细介绍了该系统的硬件电路和软件的设计.     

基于超声波飞行时间的温度测量系统实验研究

超声波测量技术具有速度快、成本低、测量范围广等优点,广泛应用于多种工业领域。为满足工业中对温度测量的需求,本文提出了超声波温度测量系统。本系统基于超声波的传播速度与环境温度的关系,以STC12单片机作为系统硬件电路控制核心,采用幅度和相位调制的矩形波作为发射波,实现在恒温箱空气介质中固定距离下的超声波飞行时间的测量,以此确定介质的平均温度。测量数据由单片机传输到上位机进行处理和显示,并与恒温箱热电偶测得的温度对照,验证实验结果。实验结果证明本系统可以准确测量温度,温度范围约在35℃—90℃。     

固体隔声层对超声波传播的影响实验研究

介绍了一种可用于实验教学的测量固体隔声层对超声波传播发生影响的实验装置,并进行了实际测量,理论和实验结果相符较好。     

固体隔声层对超声波传播的影响实验研究

本文对测量固体隔声层对超声波传播发生影响的实验装置进行了介绍 ,并进行了实际测量 ,理论和实验结果相符较好     

喷流耦合式超声位移传感器的设计

本文主要研究一种新型微位移传感器。它用超声波原理进行检测，以喷流的水柱作为超声波传播的介质，可以在恶劣环境下进行位移测量。位移等于超声波传播的速度与超声波从发到收之间传播时间的乘积。考虑到声速会随介质一水的温度的升高而增大，设计时进行了实时温度补偿，提高了系统的精度。     

基于FPGA的多通道超声波测距系统设计

超声波测距是一种非接触式连续测量方法,具有电路简单、测量精度高等优点。传统的测距系统多采用单片机实现,无法满足现代测距实时性、立体化、多向性的要求;因此设计了一种基于FPGA的多通道超声波测距系统,所有通道同时进行检测与处理,系统具有较高的扩展性。硬件部分采用US_100超声波传感器实现了超声信号的发射与接收,采用京微雅格C192芯片对回波信号进行检测和处理,实现了从2厘米到4米的距离的精确测量,测量结果送入LCD12864进行显示。软件设计采用Verilog HDL语言在Primace编辑环境下进行开发,在Modelsim软件下进行仿真,并通过HR3开发板验证了全部设计功能。测试结果表明：该测距系统运行稳定可靠,测量精度高。     

时差法超声波流量计测量精度的补偿方法*

超声波时差法测量精度的提高,不仅使流量计的测量值更加准确,更能满足工业生产监控的智能化及自动化的需求。文中对时差法流量计的测量原理以及影响因素进行分析,结合超声波接收原理,设计了过零检测电路结构,并在顺逆流的时间差的测量问题上,应用互相关算法,完成对时间测量的自补偿。实验结果显示:在采取以上补偿方法后,能有效改善流量计精度,时差测量误差小于0.8%,并提高了测量实时性。     

Using ultrasonic attenuation to monitor slurry mixing in real time

Staff at Pacific Northwest National Laboratory have developed and applied a simple ultrasonic attenuation measurement to measure slurry concentration in real time during suspension of solids settled in a large tank. This paper presents a simple single frequency ultrasonic measurement technique that demonstrates the ability of ultrasonic sensors to measure slurry concentration. Sensor calibration data show that in this attenuation regime ultrasonic signal attenuation is proportional to the applied frequency and to the slurry volume fraction. Real-time measurements of ultrasonic signal attenuation were used to track the process of slurry mixing using single sensors and sensor arrays. Results from two experiments show the use of real-time measurements of ultrasonic signal attenuation to track the process of slurry mixing in situ and to track the ability to maintain a well-mixed steady state condition. Comparison of concentration means of the ultrasonic measurements with concentration means obtained from discrete extractive measurements show that the distributions overlap and cannot be statistically distinguished. The real-time ultrasonic sensor can be used as a primary measurement method or to reduce reliance upon extractive methods to measure slurry density and solids concentration.     

On-Line Particle Size Analysis Using Ultrasonic Velocity Spectrometry

A new method is described for the determination of particle size distribution of slurries based on ultrasonic velocity spectrometry combined with gamma-ray transmission. This method shares the advantages of ultrasonic attenuation spectroscopy of being capable of analyzing highly concentrated samples without dilution. However the ultrasonic velocity method is better suited to fine particles of diameter from about 0.1 to 30 μm, a greater volume of slurry is analysed and therefore sampling errors are reduced, and precise theoretical models are readily available to permit the accurate determination of size distribution by inversion of ultrasonic velocity measurements. The method can also be used to accurately determine particle size cut points by linear correlation. Using either inversion or correlation methods, the accuracy of particle size information from ultrasonic velocity spectroscopy is significantly enhanced by the independent measurement of solids loading by gamma-ray transmission. In addition, larger sizes can be measured by combining the ultrasonic velocity method with ultrasonic attenuation measurements. The method has been tested in the laboratory on a wide variety of mineral and paint slurries. The method determined the size distribution of single component silica and alumina samples in water in agreement with laser diffraction measurements and the method successfully distinguished well and poorly dispersed TiO₂ suspensions. For composite samples the method discriminated separate TiO₂ and CaCO₃, components and determined their proportions to within 0.25% volume. In addition the method, in combination with ultrasonic attenuation measurements, determined the size fractions of iron ore slurries below 10 and 30 μm to within 1.3% and 1.0% relative respectively, when compared with laser diffraction measurement of particle size. The CSIRO is presently designing an industrial gauge which will be manufactured and installed in an industrial slurry stream in 1997.     

一种驻波型超声马达的研究

研制出一种以长条片关压电陶瓷振子作煊子的驻波型超声马达，该马达具有整体结构简单，易于制作与调整、驱动电路合理、运行稳定的特点；由实验研究，测出了其主要性能参数，利用该马达已开发出特性优异的超声步进马达及时钟模型，小型走纸机。     

超声波法测量大气折射率结构常数

 用AMK-02型超声波大气参数综合测量仪同时测量了常规气象参数和大气折射率结构常数C²_n，分析并找出了该仪器给出的C²_n在转换时刻与热丝温度脉动仪的测量结果差异较大的原因，是由于超声波法测量温度脉动精度太低，只能达到0.01 K。同时建立了另一种适用于超声波仪计算C²_n的方法，即利用该仪器准确的常规气象参数计算C²_n，其计算结果与热丝温度脉动仪的测量结果吻合较好。     

Detection and quantification of insoluble particles by ultrasound spectroscopy

The Ultrafood system, a custom-built diagnostic ultrasound device, is used to accurately measure the concentration of particulate matter in a fluctuating high temperature liquid system. The two main problems, of thermal expansion and thermal variation in ultrasonic outputs were tackled by multi-distance measurement and low frequency spectroscopy, respectively. The resulting techniques have application at laboratory, scale for investigation of particulate suspensions and for online process monitoring.     

Diffraction effects on bulk-wave ultrasonic velocity and attenuation measurements

The loss and phase advance due to diffraction are experimentally observed by measuring the amplitude and phase of radio frequency (rf) tone burst signals in the VHF range, in an ultrasonic transmission line consisting of a buffer rod with an ultrasonic transducer on one end, a couplant of water, and a solid specimen of synthetic silica glass. The measured results agree well with the calculated results from the exact integral expression of diffraction. The diffraction effects on the velocity and attenuation measured in this frequency range and their corrections are investigated to realize more accurate measurements. It is shown that attenuation measurements are influenced by diffraction losses and can be corrected by numerical calculations, and that velocity measurements are affected by the phase advance caused by diffraction. This investigation demonstrates that, in complex-mode velocity measurements, in which the velocity is determined from the measured phase of the signals, the true velocity at each frequency can be obtained by correction using the numerical calculation of diffraction. Based on this result, a new correction method in amplitude-mode velocity measurements is also proposed. In this new method, the velocity is determined from the intervals of interference output obtained by sweeping the ultrasonic frequency for the superposed signals generated by the double-pulse method. Velocity may be measured accurately at frequencies in the Fresnel region, and diffraction correction is essential to obtain highly accurate values with five significant figures or more.     

利用数字示波器测量RC电路的时间常数

利用数字示波器的脉冲信号捕捉和平均值计算等功能,设计了一个简单的实验系统,实现RC电路时间常数的准确测量,误差可以控制在1％以内.     

转动惯量实验计时装置的改进

在转动惯量实验中设计了反射式激光计时器,在不改变悬盘形状与质量分布的前提下,采用非接触式测量,可以更准确地测量摆盘的摆动周期.     

一种简单高精度超声液位计系统的设计与实现

介绍了超声时延法测距的基本原理,设计并实现了一种基于DSP的超声液位计系统,改进国内同类产品精度和稳定度偏低的问题。利用选用的AD、DSP芯片特点,给出了一种简单高效率的超声换能器驱动电路和回波采集放大电路的实现方案;使用通用16位定点DSP芯片TMS320VC5502,实现测距算法,增强了后端数字信号处理能力;使用收发一体窄带超声换能器发射和接收超声信号,其中心频率20kHz,3dB带宽1kHz。实验结果表明,本系统测量范围为0.5～18m,测量精度可达到测量距离的0.5%。