Temperature dependence of time domain reflectometry-measured soil dielectric permittivity

2008 ◽  
Vol 172 (2) ◽  
pp. 186-193 ◽  
Author(s):  
Wojciech Skierucha
Keyword(s):  
Dielectric Permittivity ◽  
Temperature Dependence ◽  
Time Domain ◽  
Time Domain Reflectometry

scholarly journals Dielectric dispersion and thermodynamic behavior of stearic acid binary mixtures with alcohol as co-solvent using time domain reflectometry

2017 ◽  
Vol 07 (04) ◽  
pp. 1750027 ◽  
Author(s):  
M. Maria Sylvester ◽  
T. Ganesh ◽  
D. J. S. Anand Karunakaran ◽  
P. Senthilkumar ◽  
Praveen G. Hudge ◽  
...  
Keyword(s):  
Dielectric Permittivity ◽  
Stearic Acid ◽  
Time Domain ◽  
Dielectric Strength ◽  
Calibration Method ◽  
Time Domain Reflectometry ◽  
Ternary Mixtures ◽  
Relaxation Dynamics ◽  
Dielectric Parameters ◽  
Strength Formula

Dielectric permittivity and relaxation dynamics of binary and ternary mixture of stearic acid on various concentration and their thermodynamic effects are studied. The static dielectric constant ([Formula: see text]), dielectric permittivity ([Formula: see text]) and dielectric loss ([Formula: see text]) are found by bilinear calibration. The relaxation time ([Formula: see text]), dielectric strength ([Formula: see text]) and the excess permittivity ([Formula: see text]) are found. The thermodynamic parameters such as enthalpy ([Formula: see text]), entropy ([Formula: see text]) and Gibb’s free energy ([Formula: see text]) are evolved. The significant changes in dielectric parameters are due to the intramolecular and intermolecular interactions in response to the applied frequency. The permittivity spectra of stearic acid–alcohol in the frequency range of 10[Formula: see text]MHz to 30[Formula: see text]GHz have been measured using picoseconds Time Domain Reflectometry (TDR). The dielectric parameters ([Formula: see text], [Formula: see text], [Formula: see text]) are found by bilinear calibration method. Influence of temperature in intermolecular interaction and the relaxation process are also studied. The FT-IR spectral analysis reveals that the conformation of functional groups and formation for hydrogen bonding are present in both binary and ternary mixtures of stearic acid.

Frequency analysis of time‐domain reflectometry (TDR) with application to dielectric spectroscopy of soil constituents

Geophysics ◽  
1999 ◽  
Vol 64 (3) ◽  
pp. 707-718 ◽  
Author(s):  
Richard Friel ◽  
Dani Or
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Frequency Domain ◽  
Time Domain ◽  
Dominant Role ◽  
Primary Objective ◽  
Time Domain Reflectometry ◽  
Complete Picture ◽  
Frequency Dependent ◽  
Additional Information

Standard analyses of time‐domain reflectometry (TDR) waveforms in environmental sciences use traveltime along waveguides and reflection amplitude to infer water content and bulk electrical conductivity, respectively. TDR waveforms contain additional information on the frequency‐dependent dielectric permittivity of media, which can be extracted through transformation of TDR waveforms into the frequency domain. The primary objective of this study was to provide a more complete picture of TDR responses in the frequency domain and to improve estimation of dielectric properties. The frequency content of TDR waveforms interacting with various constituents was measured and compared with predictions based on known dielectric properties and waveguide geometries. The study highlights the dominant role of the S11 scatter function, which describes how a TDR signal is modified by media properties and probe configuration. Scatter functions derived from transformed TDR waveforms into the frequency domain were used for estimation of frequency‐dependent dielectric properties of wet soils. The main results were (1) a more complete picture of TDR waveforms in the frequency domain; (2) estimation and use of scatter functions for TDR‐based dielectric permittivity estimation; and (3) highlights of potential usefulness and limitations of a commonly used TDR cable tester (Tektronix 1502B) and waveguide design for estimation of frequency‐dependent dielectric properties of porous media.

scholarly journals A soil non-aqueous phase liquid (NAPL) flushing laboratory experiment based on measuring the dielectric properties of soil–organic mixtures via time domain reflectometry (TDR)

2019 ◽  
Vol 23 (9) ◽  
pp. 3593-3602 ◽  
Author(s):  
Alessandro Comegna ◽  
Antonio Coppola ◽  
Giovanna Dragonetti ◽  
Angelo Sommella
Keyword(s):  
Dielectric Permittivity ◽  
Aqueous Phase ◽  
Time Domain ◽  
Corn Oil ◽  
High Mobility ◽  
Mixing Model ◽  
Time Domain Reflectometry ◽  
Pollutant Removal ◽  
Soil System ◽  
Phase Liquid

Abstract. The term non-aqueous phase liquid (NAPL) refers to a group of organic compounds with scarce solubility in water. They are the products of various human activities and may be accidentally introduced into the soil system. Given their toxicity level and high mobility, NAPLs constitute a serious geo-environmental problem. Contaminant distribution in the soil and groundwater contains fundamental information for the remediation of polluted soil sites. The present research explored the possible employment of time domain reflectometry (TDR) to estimate pollutant removal in a silt-loam soil that was primarily contaminated with a corn oil as a light NAPL and then flushed with different washing solutions. Known mixtures of soil and NAPL were prepared in the laboratory to achieve soil specimens with varying pollution levels. The prepared soil samples were repacked into plastic cylinders and then placed in testing cells. Washing solutions were then injected upward into the contaminated sample, and both the quantity of remediated NAPL and the bulk dielectric permittivity of the soil sample were determined. The above data were also used to calibrate and validate a dielectric model (the α mixing model) which permits the volumetric NAPL content (θNAPL; m3 m−3) within the contaminated sample to be determined and quantified during the different decontamination stages. Our results demonstrate that during a decontamination process, the TDR device is NAPL-sensitive: the dielectric permittivity of the medium increases as the NAPL volume decreases. Moreover, decontamination progression can be monitored using a simple (one-parameter) mixing model.

Time-domain reflectometry — parametric study for the evaluation of physical properties in soils

2009 ◽  
Vol 46 (7) ◽  
pp. 753-767 ◽  
Author(s):  
Jeffrey M. Schneider ◽  
Dante Fratta
Keyword(s):  
Dielectric Permittivity ◽  
Time Domain ◽  
Parametric Study ◽  
Capillary Rise ◽  
Time Domain Reflectometry ◽  
Relative Dielectric Permittivity ◽  
Proper Understanding ◽  
Abrupt Changes ◽  
Sand And Gravel

Time-domain reflectometry (TDR) has become a commonly used method in geotechnical engineering to measure the volumetric water content and electrical conductivity in soils. The ability of TDR to accurately determine soil properties depends on the proper understanding of the parameters that affect the propagation of an electromagnetic pulse along the TDR waveguide. The purpose of this paper is to document a parametric study and analyses aimed at gaining a better understanding of TDR measurements and to evaluate the limits in the measurement technique. A parametric study on TDR signals was performed by determining the effects of heterogeneities in the dielectric permittivity, conductivity, and magnetic permeability in sand and gravel specimens. Impedance differences in the probe head were found to contribute to inaccurate travel-time measurements that affect material dielectric permittivity calculations. The calculated relative dielectric permittivity may also be dependent on local changes in porosity near the probes. Tests performed in layered materials indicate that TDR can be used to find abrupt changes in material permittivity, such as the depth to saturation. However, problems in the determination of capillary rise may contribute to uncertainties in the proper determination of permittivity and thicknesses of layers. The presence of ferromagnetic materials was found to change the measured electromagnetic wave velocity. However, the properties of materials outside the radius defined by the probes and beneath the probes minimally affected the TDR results in the two-rod probe used.

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