Time Delay Estimation in Two-Phase Flow Investigation Using theγ-Ray Attenuation Technique

Robert Hanus,Dariusz Świsulski,Leszek Petryka,Marcin Zych

doi:10.1155/2014/475735

Abstract

Time delay estimation is an important research question having many applications in a range of technologies. Measurement of a two-phase flow in a pipeline or an open channel using radioisotopes is an example of such application. For instance, the determination of velocity of dispersed phase in that case is based on estimation of the time delay between two stochastic signals provided by scintillation probes. The proper analysis of such signals, usually in presence of noise, requires the use of advanced statistical signal processing. In this paper, the simulation studies of time delay estimation were carried out with the use of the following differential methods: average magnitude difference function, and average square difference function and proposed combined methods comprising the above-mentioned differential and cross-correlation functions are presented. Attached simulations have been carried out for models of stochastic signals corresponding to the signals obtained in gamma-ray absorption measurements of gas-liquid flow in a horizontal pipeline. The standard uncertainties of time delay estimations have been determined for each of the methods. Improved metrological properties have been stated in the combined methods in comparison with the classical cross-correlation procedure.

Highlights

Determination of the time delay between signals is a significant issue in many fields such as radar and sonar technologies, seismology, communications, and medical diagnostics
The ε has been introduced in order to prevent the division by zero, because the average magnitude difference function (AMDF) and average square difference function (ASDF) functions in an ideal case of a lack of noise can assume a null for τ = τ0
During flow measurements signals provided by scintillation probes contain statistical information about the studied mixture and disturbing signals caused by the gamma radiation background, electronic noise, and fluctuations of the gamma ray decay

Summary

Introduction

Determination of the time delay between signals is a significant issue in many fields such as radar and sonar technologies, seismology, communications, and medical diagnostics. Over the past few decades numerous methods and algorithms have been developed ranging from cross-correlation to the advanced blind channel identification techniques [1,2,3,4,5,6]. Estimation of the time delay is essential in contactless measurements of flow parameters, especially in the following two-phase mixtures transportation as liquid-gas, liquid-solids, or gas-solids. In these measurements, mutually delayed stochastic signals may be provided by sensors of such type as capacitance, optical, electrostatic, and thermometric or scintillation probes, situated on a wall of a pipeline or open channel [7,8,9]. The measurement of time delay allows us the mean velocity determination of the flow dispersed phase

Methods

Results

Conclusion