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.

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.

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 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 Horizontally Elongated Time Domain Reflectometry System for Evaluation of Soil Moisture Distribution

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6834
Author(s):  
Dong-Ju Kim ◽  
Jung-Doung Yu ◽  
Yong-Hoon Byun
Keyword(s):  
Water Content ◽  
Time Domain ◽  
Field Testing ◽  
Time Domain Reflectometry ◽  
Coaxial Cable ◽  
Moisture Distribution ◽  
Segment Length ◽  
Dry Conditions ◽  
Average Water ◽  
The Difference

The objective of this study was to develop a horizontally elongated time domain reflectometry (HETDR) system to evaluate the water content in nonuniformly wetted soils. The HETDR probe consists of three rods of stainless steel and a cuboid head: A center electrode and two outer electrodes are connected to the inner and outer conductors of a coaxial cable, respectively. An acrylic container divided into several segments was used to prepare nonuniformly wetted soils with different water contents for a series of model tests. The HETDR probe was placed horizontally at the middle height of each soil specimen, while a conventional time domain reflectometry (TDR) probe was applied vertically on the surface of the specimen. The experimental results show that as the soil water content (SWC) at a segment increases, the average amplitude decreases and the duration increases. The estimated SWC increases with the measured SWC, and especially, the difference between actual segment length and the segment length estimated from the HETDR probes is significant under dry conditions. This study demonstrates that HETDR may be a promising field-testing method for evaluating the average water content in nonuniformly wetted soils.

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.

The Analysis of a Transmission Line Crosstalk in the Time Domain Based on First-Order Upwind

2014 ◽  
Vol 543-547 ◽  
pp. 813-816
Author(s):  
Yin Han Gao ◽  
Tian Hao Wang ◽  
Jun Dong Zhang ◽  
Kai Yu Yang ◽  
Yu Zhu
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Time Domain ◽  
Splitting Method ◽  
Discontinuous Solution ◽  
Characteristic Line ◽  
First Order ◽  
The Difference ◽  
Leapfrog Scheme ◽  
The Time Domain

This article will combine the difference scheme of first-order upwind with the multi-conductor transmission lines equation to analysis the multi-conductor transmission lines crosstalk in the time domain. First-order upwind is a finite difference algorithm in the time domain; it has a first order accuracy, in the discontinuous solution there is no non-physics-oscillation, when simulate the signal. The flux splitting method which is applied to the first-order upwind solved the problem that the characteristic line direction of the wind type make plus or minus transformation along with the coefficient, make the programming simple. In this paper, simulation results of transmission line crosstalk in this algorithm will be compared with the traditional leapfrog scheme, to verify its effectiveness.

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