Laboratory tests of a time-domain reflectometry system for frazil ice detection

1999 ◽  
Vol 26 (2) ◽  
pp. 168-176 ◽  
Author(s):  
Norbert E Yankielun ◽  
John J Gagnon
Keyword(s):  
Dielectric Constant ◽  
Transmission Line ◽  
Time Domain ◽  
Detection System ◽  
Time Domain Reflectometry ◽  
Propagation Time ◽  
Time Data ◽  
Parallel Transmission ◽  
Frazil Ice ◽  
Ice Detection

A prototype, electromagnetic-based frazil ice detection system (patent pending) has been developed and tested under simulated frazil ice accretion conditions in an environmentally controlled flume. The system employs a time-domain reflectometer (TDR) and specially designed transmission line sensor to monitor the accretion of frazil ice by measuring the propagation time along the sensor when it is submerged. Changes in the round-trip travel time of the TDR pulse result from a decrease in the localized bulk dielectric constant as frazil ice accretes and displaces water around the sensor. Two frazil detection sensor configurations were tested, a parallel transmission line probe and a semicylindrical mesh coaxial probe. During 2 h long experiments, the TDR clearly indicated a decreasing probe propagation time as frazil ice continued to accrete. This is indicative of the decreasing bulk dielectric constant of the frazil ice and water mix. Continuous real-time data from the TDR were recorded. From these data, an estimate of volumetric ice fraction was calculated using a simple linear dielectric mixing equation. Volumetric ice fractions estimates for both probe configurations were calculated to increase from approximately 0.02 to 0.18 during the test. The system shows promise for detection and measurement of frazil ice growth and accretion in freshwater bodies.Key words: frazil ice, trash rack, water intake, icing detection, time-domain reflectometry, TDR.

Laboratory Approach to Determine Roller Compacted Concrete Mixture Electrical Characteristics Using a New Time-Domain Reflectometry Interpretation Method

2021 ◽  
pp. 036119812110363
Author(s):  
Issa M. Issa ◽  
Dan G. Zollinger ◽  
Ibrahim Onifade ◽  
Robert L. Lytton
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Electrical Properties ◽  
Moisture Content ◽  
Transmission Line ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Test Configuration ◽  
Roller Compacted Concrete ◽  
Line Theory

This work deals with using time-domain reflectometry (TDR) to measure the electrical properties of roller compacted concrete (RCC). It is well known that TDR provides a non-destructive method to measure the dielectric constant toward an estimation of moisture content for soil materials. However, few studies have used TDR to determine the moisture content in concrete because of the inability to obtain TDR traces after the concrete hardens. To obtain TDR traces, a transmission circuit is initiated where a wave signal moves through the medium and reflects back in accordance with transmission line theory. In the literature, the TDR waveform has been interpreted empirically to estimate the relative permittivity (or dielectric constant) and electrical conductivity in a given material relative to the determination of associated water content. However, empirical models tend to ignore certain aspects related to the electrical properties of a medium, which has made interpretation of TDR measurements prone to systematic errors. In this paper, a new approach of test configuration and TDR response interpretation has been developed. For the test setup, the approach uses disposable metal probes that can be embedded into the concrete at different depths to obtain the TDR traces. The approach also employs the transmission line equation to estimate the dielectric constant, electrical conductivity, and reflectivity of an instrumented RCC mixture. These properties will affect the understanding of the RCC pavement behavior, especially curling and warping behavior, placement density, and development of long-term distresses.

An Innovative Use of TDR Probes: First Numerical Validations with a Coaxial Cable

2018 ◽  
Vol 23 (4) ◽  
pp. 437-442
Author(s):  
Raffaele Persico ◽  
Iman Farhat ◽  
Lourdes Farrugia ◽  
Sebastiano D'Amico ◽  
Charles Sammut
Keyword(s):  
Magnetic Properties ◽  
Transmission Line ◽  
Time Domain ◽  
Numerical Data ◽  
Time Domain Reflectometry ◽  
Coaxial Cable ◽  
Transmission Line Model ◽  
Properties Of Materials

In this paper we propose a study regarding some possibilities that can be offered by a time domain reflectometry (TDR) probe in retrieving both dielectric and magnetic properties of materials. This technique can be of interest for several applications, among which the characterization of soil in some situations. In particular, here we propose an extension of the paper “Retrieving electric and magnetic propetries of the soil in situ: New possibilities”, presented at the IWAGPR, held in Edinburgh in 2017, and as a new contribution we will validate a transmission line model with numerical data simulated by the CST code.

Distributed Strain Sensing Using Carbon Nanotube Thin Films and Electrical Time-Domain Reflectometry

2018 ◽  
Author(s):  
Bo Mi Lee ◽  
Kenneth J. Loh ◽  
Francesco Lanza di Scalea
Keyword(s):  
Thin Films ◽  
Carbon Nanotube ◽  
Transmission Line ◽  
Time Domain ◽  
Structural Response ◽  
Time Domain Reflectometry ◽  
Distributed Sensing ◽  
Uniaxial Tensile ◽  
Electromagnetic Signal ◽  
Single Measurement

Nondestructive inspection (NDI) is an effective technique to inspect, test, or evaluate the integrity of materials, components, and structures without interrupting the serviceability of a system. Despite recent advances in NDI techniques, most of them are either limited to sensing structural response at their instrumented locations or require multiple sensors and measurements to localize damage. In this study, a new NDI system that could achieve distributed sensing using a single measurement was investigated. Here, piezoresistive carbon nanotube (CNT)-polymer thin film sensors connected in a transmission line setup were interrogated using electrical time-domain reflectometry (ETDR). In ETDR, an electromagnetic signal is sent from one end of the transmission line. When the signal encounters the sensor, it can partially reflect and be captured at the same point. The characteristics of the reflected signal depend on the sensor’s impedance, which is correlated to structural response, deformation, or damage. The advantage of this is that distributed sensing along the entire transmission line can be achieved using a single measurement point. To validate this concept, CNT-polymer thin films that were integrated with a transmission line are subjected to uniaxial tensile strains applied using a load frame. The ETDR signals were analyzed to assess the system’s sensing performance.

Impact of density on the hydraulic properties of peat and the time domain reflectometry (TDR) moisture calibration curve

2005 ◽  
Vol 42 (1) ◽  
pp. 279-286 ◽  
Author(s):  
Anushka Shibchurn ◽  
Paul J Van Geel ◽  
Paula L Kennedy
Keyword(s):  
Dielectric Constant ◽  
Soil Moisture ◽  
Water Content ◽  
Time Domain ◽  
Calibration Curve ◽  
Hydraulic Properties ◽  
Time Domain Reflectometry ◽  
Organic Soils ◽  
Dry Density ◽  
Water Contents

The hydraulic properties of a peat used in a commercial peat biofilter were evaluated to determine their relationship with density and to establish a time domain reflectometry (TDR) calibration curve for water content as a function of the measured dielectric constant. The peat studied was a milled Sphagnum peat with a high organic content (99%). The dry densities evaluated in this study ranged from 90 to 180 kg/m3. The saturated hydraulic conductivity (Ks) decreased with an increase in dry density (ρdry) and was found to follow a log-linear relationship (Ks = 0.2462 exp(–0.0438ρdry), correlation coefficient R2 = 0.9789). As expected, the soil moisture curve was impacted by density, with a higher density resulting in higher water contents for a given suction. The data were fit to the van Genuchten relationship. A TDR calibration curve was generated at five different densities. A comparison of the curves indicates that the water content as a function of dielectric constant was not dependent on density because of the significantly larger dielectric constant (Ka) of water compared with those of peat solids and air-filled voids. The TDR calibration curve for the peat evaluated in this study (volumetric water content Θv = 0.2667 ln(Ka) – 0.1405, R2 = 0.9564) predicted higher water contents for a given dielectric constant compared with those from similar calibration curves for peat published in the literature. The data were compared with those from six other studies and indicated that the TDR calibration varied for different organic soils. The density-dependent hydraulic parameters and TDR calibration curve are important parameters needed to study the hydraulics of peat biofilters.Key words: peat, TDR, time domain reflectometry, density, hydraulics, soil moisture.

scholarly journals Sequence and spread spectrum time domain reflectometry for transmission line analysis

2007 ◽  
Author(s):  
Jacklyn Reis ◽  
Agostinho L. S. Castro ◽  
João C. W. A. Costa ◽  
Jaume R. I. Riu ◽  
Klas Ericson
Keyword(s):  
Transmission Line ◽  
Time Domain ◽  
Spread Spectrum ◽  
Time Domain Reflectometry ◽  
Line Analysis

Self-sensing time domain reflectometry method for damage monitoring of a CFRP plate using a narrow-strip transmission line

2014 ◽  
Vol 58 ◽  
pp. 59-65 ◽  
Author(s):  
Akira Todoroki ◽  
Hiroumi Kurokawa ◽  
Yoshihiro Mizutani ◽  
Ryosuke Matsuzaki ◽  
Tetsuo Yasuoka
Keyword(s):  
Transmission Line ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Narrow Strip ◽  
Cfrp Plate ◽  
Damage Monitoring ◽  
Sensing Time

scholarly journals Time domain reflectrometry measurements using a movable obstacle for the determination of dielectric profiles

2008 ◽  
Vol 6 ◽  
pp. 1-4
Author(s):  
B. Will ◽  
M. Gerding ◽  
S. Schultz ◽  
B. Schiek
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Time Domain ◽  
Measurement Techniques ◽  
Measurement Data ◽  
Time Domain Reflectometry ◽  
Dielectric Measurement ◽  
Effective Dielectric Constant ◽  
Pulse Delay

Abstract. Microwave techniques for the measurement of the permittivity of soils including the water content of soils and other materials, especially TDR (time domain reflectometry), have become accepted as routine measurement techniques. This summary deals with an advanced use of the TDR principle for the determination of the water content of soil along a probe. The basis of the advanced TDR technique is a waveguide, which is inserted into the soil for obtaining measurements of the effective soil permittivity, from which the water content is estimated, and an obstacle, which can mechanically be moved along the probe and which acts as a reference reflection for the TDR system with an exactly known position. Based on the known mechanical position of the reference reflection, the measured electrical position can be used as a measure for the effective dielectric constant of the environment. Thus, it is possible to determine the effective dielectric constant with a spatial resolution given by the step size of the obstacle displacement. A conventional industrial TDR-system, operating in the baseband, is used for the signal generation and for the evaluation of the pulse delay time of the obstacle reflection. Thus, a cost effective method for the acquisition of the dielectric measurement data is available.

scholarly journals Influência da Densidade na Estimativa da Umidade Volumétrica em um Latossolo Vermelho-Amarelo (Influence of Density in Estimation of Volumetric Moisture an Oxisol)

2013 ◽  
Vol 5 (5) ◽  
pp. 1056 ◽  
Author(s):  
Carlos Alexandre Barros de Almeida ◽  
Antonio Celso Dantas Antonino ◽  
Rejane Magalhaes de Mendonça Pimentel ◽  
Carlos Alberto Brayner de Oliveira Lira ◽  
José Romualdo de Sousa Lima
Keyword(s):  
Dielectric Constant ◽  
Soil Moisture ◽  
Bulk Density ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Calibration Equation ◽  
Moisture Sensor ◽  
Soil Moisture Sensor ◽  
Volumetric Soil Moisture ◽  
Use Of Time

A estimativa da umidade volumétrica do solo pode ser realizada por vários métodos, entre eles destaca-se o uso da Reflectometria no Domínio do Tempo (TDR). Este tem como uso padrão, uma equação que relaciona a constante dielétrica do meio com a umidade sugerida pelo manual do fabricante. Este estudo objetivou avaliar a medição a umidade volumétrica do solo pelo sensor CS616. Na sua realização foi feita a calibração deste sensor em laboratório, para quatro camadas em um Latossolo Vermelho-Amarelo que apresentam densidades diferentes. Foram utilizados cinco métodos diferentes, três consagrados pela literatura e outros dois sugeridos por esse estudo. Os resultados permitiram concluir que nesse solo há uma grande disparidade entre os resultados encontrados durante a calibração do sensor e que a densidade do solo é um parâmetro importante nas medições de umidade do solo.Palavras-chave: reflectometria no domínio do tempo, medição direta da água no solo, equação de calibração Influence of Density in Estimation of Volumetric Moisture an Oxisol ABSTRACTThe estimation of volumetric soil moisture can be accomplished by various methods, among them stands out the use of Time Domain Reflectometry (TDR). This standard is to use an equation that relates the dielectric constant of the medium with humidity suggested by the manufacturer's manual. This study aimed to evaluate the measured volumetric soil moisture sensor for the CS616. In its realization was made to calibrate this sensor in the laboratory for four layers in an Latossolo Vermelho-Amarelo which have different densities. Was used five different methods, the literature established three and two others suggested by this study. The results showed that this soil there is great disparity between the results obtained during calibration of the sensor and the bulk density is an important parameter in measurements of soil moisture.Keywords: time domain reflectometry, direct measurement of soil water, calibration equation

scholarly journals Sequence Time Domain Reflectometry for Transmission Line Analysis

2007 ◽  
Author(s):  
Jacklyn Reis ◽  
Agostinho Castro ◽  
João Crisostomo Weyl Albuquerque Costa ◽  
Jaume Riu ◽  
Klas Ericson
Keyword(s):  
Transmission Line ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Line Analysis

scholarly journals Laboratory Evaluation of Railroad Crosslevel Tilt Sensing Using Electrical Time Domain Reflectometry

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4470
Author(s):  
Sijia Li ◽  
Chi-Lin Chen ◽  
Kenneth J. Loh
Keyword(s):  
Transmission Line ◽  
Time Domain ◽  
Pulse Signal ◽  
Time Domain Reflectometry ◽  
Laboratory Evaluation ◽  
Track Geometry ◽  
Railroad Tracks ◽  
Printed Sensors ◽  
The Difference ◽  
Tilt Sensors

Crosslevel is defined as the difference in elevation between the top surface of two railroad tracks. Severe changes in crosslevel, for example, due to earthquakes, ground settlement, or crushed ballasts, affect track geometry and can cause train derailment. Therefore, the objective of this study was to monitoring railroad crosslevel by using electrical time domain reflectometry (ETDR) to simultaneously interrogate multiple capacitive tilt sensor prototypes connected in a transmission line. ETDR works by propagating an electrical pulse signal from one end of the transmission line and then monitoring the characteristics of each reflected pulse, which is affected by the capacitance (or tilt) of the sensors. This study begins with a discussion of the capacitive tilt sensor’s design. These 3D-printed sensors were tested to characterize their tilt sensing performance. Then, multiple tilt sensors were connected in a transmission line and interrogated by ETDR. The ability to use ETDR to multiplex and interrogate sensors subjected to different angles of tilt was validated.

Sign in / Sign up

Export Citation Format

Share Document