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A PULSED ULTRASONIC FLOWMETER EMPLOYING TIME DOMAIN METHODS.

机译：脉动超声波流量计应用时域方法。

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摘要

In this thesis the flow velocity profile across a vessel is determined. Knowledge of the velocity profile is valuable in determining the condition of the vessel and the heart. The time domain method (TDM) being described is an ultrasonic approach for determining flow velocity profiles. Currently available ultrasonic methods transmit more energy into the body than the TDM for the same degree of accuracy and they cannot correct for vessel motion.;In this work, the TDM is first studied by computer simulation. In the simulation a variety of parameters are used: vessel diameter, beam width of the transducer, the amount of damping of the transducer, and the type of velocity profile. Next, the TDM is applied to determine the velocity profile of buttermilk (substitute for blood) pumped through tubing. The application of the TDM on the buttermilk is in agreement with the simulation. Included is a discussion of the sources of errors resulting from each system parameter.;The motion of the tubing can be eliminated by first lining up the second echo with the first at the tube wall where there is a large echo, then applying the TDM. With two ultrasonic pulses, the TDM achieves a precision of 3% in estimating midstream flow. Other available ultrasonic means must use many more pulses (hundreds) to achieve the same precision.;The TDM measures the velocity profile by transmitting two short ultrasonic pulses separated by a known amount of time. Two echoes from the two pulses scattered from the medium are amplified, digitalized, and then stored in a high speed memory in which the digitalized data can be read by the computer used for digital signal processing. The TDM then cuts out a portion of the first echo at a desired range and overlays and moves it across the second echo. The point at which the cut-out portion of the first echo is maximally correlated with the second echo is the change in range which the scatterers of the second echo have moved with respect to the first echo in the intervening time between the transmission of the two pulses. From the change in range information and the time interval between the two pulses, the radial velocity of the scatterers can be determined.
机译：在本文中，确定了穿过容器的流速分布。速度分布图的知识对于确定血管和心脏的状况非常重要。所描述的时域方法（TDM）是一种用于确定流速分布的超声方法。在相同的精确度下，目前可用的超声方法比TDM将更多的能量传递到体内，并且它们无法校正血管运动。在这项工作中，首先通过计算机仿真研究TDM。在仿真中使用了各种参数：容器直径，传感器的束宽，传感器的阻尼量以及速度曲线的类型。接下来，应用TDM来确定通过管道泵送的酪乳（代替血液）的速度分布。 TDM在酪乳上的应用与仿真一致。包括对每个系统参数导致的错误源的讨论。可以通过先将第二个回声与第一个回声对齐并在存在较大回声的管壁处消除管道的运动，然后应用TDM来消除。通过两个超声波脉冲，TDM在估算中游流量时可达到3％的精度。其他可用的超声波装置必须使用更多的脉冲（数百个）才能达到相同的精度。TDM通过传输两个短的超声波脉冲（间隔已知的时间）来测量速度分布。来自介质的两个脉冲的两个回波被放大，数字化，然后存储在高速存储器中，数字化数据可以通过用于数字信号处理的计算机读取，在高速存储器中。然后，TDM会在所需范围内切出一部分第一回波，并将其覆盖并移动到第二回波上。第一回波的切除部分与第二回波最大相关的点是第二回波的散射体在两次发射之间的间隔时间内相对于第一回波移动的范围变化。脉冲。根据范围信息的变化和两个脉冲之间的时间间隔，可以确定散射体的径向速度。

著录项

  • 作者

    FOSTER, STEVEN GERALD.;

  • 作者单位

    University of Illinois at Urbana-Champaign.;

  • 授予单位 University of Illinois at Urbana-Champaign.;
  • 学科 Engineering Biomedical.;Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 1985
  • 页码 170 p.
  • 总页数 170
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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