Simultaneous measurements of dynamic values using the transit time method
01 Apr 1992-Vol. 41, Iss: 2, pp 251-255
TL;DR: In this paper, the problem of simultaneous and accurate measurements of two dynamic values, time dependencies of flow velocity and ultrasound velocity in the flow, is analyzed, and a theory of the transit time method has developed, and the theoretical model of a microprocessor-based measuring system has been derived.
Abstract: The problem of simultaneous and accurate measurements of two dynamic values, time dependencies of flow velocity and ultrasound velocity in the flow, is analyzed. In order to measure two dynamic values simultaneously a theory of the transit time method has developed, and the theoretical model of a microprocessor-based measuring system has been derived. The ways to improve the accuracy and information of such dual-channel measurement systems have been examined. It is shown that invariance between two channels of a measurement system can be achieved when dynamic, nonlinear, parametric models of these channels are identified in real time during the process of measurement, and when the multipulse irradiation of flow is used. The results of computer simulation of transit time method dynamic errors are represented. A method of minimizing these errors has been proposed. >
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01 Jan 2005
TL;DR: In this article, the authors used short ultrasonic wave pulses and the time-of-flight (TOF) method for probing of liquid flow measurements to control cooling and heating systems.
Abstract: Liquid flow measurements are widely used to control cooling and heating systems. Flow sensor systems based on ultrasonic time-of-flight technology provide a reliable, rugged, and easy to integrate solution. Most important, ultrasound is also a cost – effective long term solution for flow problems. Short ultrasonic wave pulses [1, 2] and the time-of-flight method are used for probing of the liquid. The flowing liquid causes time differences, frequency variations and phase shifts in ultrasonic signals, which are subsequently digitally evaluated by a flow meter electronics. The principle behind the measurement is that sound waves traveling with the flow of liquid will travel faster than those traveling against it. The difference in the time-of-flight of the signals is an indication for the flow rate of the fluid. Most flow meters are designed to measure a flow that follows a certain flow velocity profile. The exact behavior of the velocity profile will depend on many factors such as meter installation effects [4, 5], inlet pipe wall roughness [6], flow rate and viscosity of the fluid [7].
2 citations
Cites methods from "Simultaneous measurements of dynami..."
...Short ultrasonic wave pulses [1, 2] and the time-offlight method are used for probing of the liquid....
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07 Nov 1995
TL;DR: The problem of non-invasive ICP monitoring is analyzed, the new non- invasive method and technique in accordance with the developed ultrasonic transit time method is proposed and a computer based ICP waves' measuring system is introduced.
Abstract: Invasive intracranial pressure (ICP) sensors are potentially dangerous for neurosurgical patients. The problem of non-invasive ICP monitoring is analyzed, the new non-invasive method and technique in accordance with the developed ultrasonic transit time method is proposed and a computer based ICP waves' measuring system is introduced. The resolution of this system is less then 0.1 mmHg and the measuring channel's capacity is above 1.0 kbit/s which allows one to resolve up to 11 harmonics of ICP pulse waves. The results of clinical tests and simultaneous comparative analysis of invasive and non-invasive ICP measuring systems' data are shown and discussed.
1 citations
References
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TL;DR: A new method for in vivo sound measurement in the reflection mode using the mean sound speed between the reflector and linear array transducer is measured using the following three parameters: time of flight, time ofFlight difference, and distance between two receiver elements.
Abstract: This paper describes a new method for in vivo sound measurement in the reflection mode. The mean sound speed between the reflector and linear array transducer is measured using the following three parameters: time of flight, time of flight difference, and distance between two receiver elements. To detect time of flight, the system delay-line time compensator is adjusted to obtain the sharpest reflector image. This method was evaluated in vivo in human livers, specifically 26 normal, 27 cirrhotic, and 15 fatty livers. The mean sound speed between diaphragm and the transducer was obtained. The measured sound speed was significantly higher in cirrhotic livers and lower in fatty livers.
45 citations
TL;DR: In this article, the double peak cross-correlation function caused by the saddle velocity distribution encountered in oil/gas risers is measured and a theoretical model for the measurement of bubble velocity is developed and supported by experimental results.
Abstract: The pulsed ultrasonic cross-correlation system is attractive for measuring the dynamic flow characteristics of two component liquid/gas mixtures because the sensors are invasive but do not extend into the pipe and, in contrast to previous continuous wave systems, have a uniform spatial sensitivity due to the absence of standing waves. The potential for measuring the flow characteristics in industrial processes including oil/gas risers is demonstrated by the measurement of the double peak cross-correlation function caused by the 'saddle' velocity distribution encountered in these risers. A theoretical model for the measurement of bubble velocity is developed and supported by experimental results.
30 citations
TL;DR: In this paper, two measuring systems driven by microcomputer are presented: flowrate ultrasonic measurements and coherent anti-Stokes Raman spectroscopy, where the integration of standard interfaces and specific electronics made it possible to develop these two applications from a single basic system.
Abstract: Two measuring systems driven by microcomputer are presented: flowrate ultrasonic measurements and coherent anti-Stokes Raman spectroscopy. It is shown how the integration of standard interfaces and specific electronics made it possible to develop these two applications from a single basic system.
12 citations
TL;DR: In this article, a linear spark was used as the source of the ultrasound pulse and two quartz crystals downstream and upstream of the source were used as receivers to measure the flow properties at the intake and exhaust of an engine.
Abstract: A new ultrasonic meter is described which uses a linear spark as the source of the ultrasound pulse. Two quartz crystals downstream and upstream of the source act as receivers. The time taken by the pulse to reach the receivers is determined by the velocity and temperature of the gases. The flow properties at the intake and exhaust of an engine are measured using this meter.
7 citations
01 Jan 1987
TL;DR: In this paper, an acousto-optic modulator is used to focus green 5145-Angstrom laser light, gated into narrow pulses, onto a functioning acoustic charge transport (ACT) device.
Abstract: Conventional Acoustic Charge Transport (ACT) devices employ a Schottky metal plate over the top of the transport channel, which provides a means of depleting the channel and of forcing the charge packets to propagate in the interior of the epitaxial layer. We report an ACT channel structure in which the optically opaque metal channel plate is replaced by a p+ doped GaAs layer, allowing the entire top surface of the channel to be light sensitive. We have demonstrated this principle by focusing green 5145-Angstrom laser light, gated into narrow pulses by an acousto-optic modulator, onto a functioning ACT device of this type. Electron-hole pairs generated in the semiconductor are separated by the depletion potential, with the electrons swept downward into the channel and then carried along in synchronism with the acoustic wave to the output contact. Experiments show that the device works as a parallel-input delay line with a movable optical input: the optically-injected pulses reach the output after a delay which is equal to the acoustic delay between the laser spot position and the output contact. In addition, we also show simultaneous optical and electrical signals on such a device.
3 citations