scholarly journals Variations in Velocity and Sensitivity of Electromagnetic Waves in Transmission Lines Configured in Model Piles with Necking Defects Containing Soils

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6541
Author(s):  
Jung-Doung Yu ◽  
Sang Yeob Kim ◽  
Jong-Sub Lee
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Time Domain ◽  
Electromagnetic Waves ◽  
Electrical Wire ◽  
Different Types ◽  
Bored Piles ◽  
Time Domain Reflectometer ◽  
Water Contents ◽  
Soil Water Contents

This study investigates variations in the velocity and sensitivity of electromagnetic waves in transmission lines configured in defective model piles for the detection of necking defects containing soil. Experiments are performed with model piles containing defects filled with different materials, such as air, sands, and clay. Five different types of transmission lines are configured in model piles. The electromagnetic waves are generated and detected using a time domain reflectometer. The velocity of electromagnetic waves is highest when the defect is filled with air, and it decreases with an increase in the water content. The velocity is lowest when the defect is filled with clay. The sensitivity of transmission lines for detecting defects decreases with an increase in soil water contents. The transmission line with a single electrical wire and epoxy-coated rebar exhibits the highest sensitivity, followed by that with three and two parallel electrical wires. Transmission lines with a single electrical wire and uncoated rebar and those with two parallel electrical wires wrapped with a sheath exhibit poor sensitivity when the defect is filled with clay. This study demonstrates that electromagnetic waves can be effective tools for detecting necking defects with wet and conductive soils in bored piles.

TDR Analysis on Short Transmission Lines

2014 ◽  
Author(s):  
Nicholas Konkol
Keyword(s):  
Failure Analysis ◽  
Transmission Line ◽  
Transmission Lines ◽  
Time Domain ◽  
System Level ◽  
Electrical Failure ◽  
Advantages And Disadvantages ◽  
System A ◽  
Time Domain Reflectometer ◽  
Line Analysis

Abstract Transmission line analysis is done in electrical failure analysis labs in order to find root causes that result in system level failures. After a fault is narrowed to a particular signal in a system, a Time Domain Reflectometer (TDR) can be used to analyze the physical transmission line associated with the signal. The transmission lines on smartphones often have inaccessible signal vias, few or no ground vias, probe points that are difficult to see, and short transmission lines. One solution that can alleviate these problems is to design a TDR Accessory Card. This paper discusses the processes involved in testing long and short transmission lines, providing the comparison between the expected and actual TDR measurement and the advantages and disadvantages of TDR, explaining four main points for using a TDR Accessory Card and two reasons for not using the TDR Accessory Card.

scholarly journals Smart Sensing Using Electromagnetic Waves for Inspection of Defects in Rock Bolts

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2821 ◽  
Author(s):  
Jung-Doung Yu ◽  
Jong-Sub Lee
Keyword(s):  
Transmission Lines ◽  
Electromagnetic Waves ◽  
Concrete Block ◽  
Rock Slopes ◽  
Rock Bolts ◽  
Different Types ◽  
Smart Sensing ◽  
The Stability ◽  
Time Domain Reflectometer ◽  
Good Agreement

The stability of tunnels and rock slopes is adversely affected by defects in rock bolts. This study investigates the suitability of the smart sensing method using electromagnetic waves for inspecting defects in rock bolts. Experiments were performed with one fully grouted and eight defective rock bolts, out of which five have non-grouted parts at the ends with different non-grouted ratios, and three have different types of voids. Electromagnetic waves were generated and detected using a time domain reflectometer by configuring two-conductor transmission lines in the rock bolts. Results show that electromagnetic waves are reflected both at defects and ends of rock bolts. The electromagnetic wave velocity increases with an increase in the non-grouted ratio and decreases when rock bolts are embedded in a concrete block simulating rock mass. The estimated locations of defects found by electromagnetic waves are in good agreement with actual defect locations. This study demonstrates that smart sensing using electromagnetic waves is an effective method for inspecting and determining defect locations and the non-grouted ratio of rock bolts.

scholarly journals Analysis on the Influence of Transmission Lines span on Passive Interference in Shortwave

2018 ◽  
Vol 64 ◽  
pp. 05004
Author(s):  
Ying Lu ◽  
Zhibin Zhao ◽  
Jian gong Zhang ◽  
Zheyuan Gan
Keyword(s):  
Electromagnetic Field ◽  
Transmission Line ◽  
Transmission Lines ◽  
Electromagnetic Scattering ◽  
Electromagnetic Waves ◽  
Short Wave ◽  
Critical Distance ◽  
Observation Point ◽  
Radio Station ◽  
Passive Interference

The passive interference of transmission lines to nearby radio stations may affect the effective reception and transmission of radio station signals. Therefore, the accurate calculation of the electromagnetic scattering of transmission lines under the condition of external electromagnetic waves is the basis for determining the reasonable avoidance spacing of the two. For passive stations operating in short-wave frequencies, passive interference is mainly generated by the tower, and span is one of the most significant factors affecting passive interference. This paper uses the method of moments to carry out the passive interference calculations under normal circumstances, expounds the method of calculating the electromagnetic field of transmission line at the same time. And elaborates the method for calculating the electromagnetic field of the transmission line, obtains the space electric field intensity of the transmission line at the same working frequency and space location of the plane wave. Applying the approximate formula to calculate the formula for the span and critical distance between the observation point and the transmission line.

scholarly journals Analysis on the Influence of the Height of Tower on Passive Interference in shortwave

2018 ◽  
Vol 64 ◽  
pp. 05005
Author(s):  
Ying Lu ◽  
Zhibin Zhao ◽  
Jian gong Zhang ◽  
Zheyuan Gan
Keyword(s):  
Transmission Line ◽  
Method Of Moments ◽  
Transmission Lines ◽  
Electromagnetic Scattering ◽  
Electromagnetic Waves ◽  
Short Wave ◽  
Radio Station ◽  
Radio Stations ◽  
Working Frequency ◽  
Passive Interference

The passive interference of transmission lines to nearby radio stations may affect the effective reception and transmission of radio station signals. Therefore, the accurate calculation of the electromagnetic scattering of transmission lines under the condition of external electromagnetic waves is the basis for determining the reasonable avoidance spacing of the two. For passive stations operating in short-wave frequencies, passive interference is mainly generated by the tower. This paper uses the method of moments to perform passive interference calculations under normal circumstances, And elaborates the method for calculating the electromagnetic field of the transmission line, obtains the space electric field intensity of the transmission line at the same working frequency and space location of the plane wave. Uses the approximate formula to inductive the formula for calculating height of tower and the protective distance.

scholarly journals Locating the frozen–unfrozen interface in soils using time-domain reflectometry

1982 ◽  
Vol 19 (4) ◽  
pp. 511-517 ◽  
Author(s):  
T. H. W. Baker ◽  
J. L. Davis ◽  
H. N. Hayhoe ◽  
G. C. Topp
Keyword(s):  
Transmission Lines ◽  
Time Domain ◽  
Freezing Temperature ◽  
Time Domain Reflectometry ◽  
Temperature Measurements ◽  
Soil Freezing ◽  
Electromagnetic Pulses ◽  
The Time Domain ◽  
Time Domain Reflectometer ◽  
Liquid And Solid Phases

The time-domain reflectometry technique was compared with the temperature measurement method for locating the frozen–unfrozen interface in water and sandy soils. This technique depends on the high-frequency (1–1000 MHz) electrical properties of water that change significantly and abruptly between the liquid and solid phases. Parallel wire transmission lines were inserted into the soil to guide electromagnetic pulses produced by a time-domain reflectometer (TDR). The frozen–unfrozen interface produced reflections measured by the TDR which were in turn used to locate the interface as it moved along the transmission line. In the laboratory it was possible to locate the interface using the TDR to within ±0.5 cm and in the field to within ±2.4 cm. These errors were equal to those associated with the temperature measurements. Keywords: soil freezing, temperature measurements, dielectric constant, time-domain reflectometry.

Application of time domain reflectometer for detecting necking defects in bored piles

2018 ◽  
Vol 100 ◽  
pp. 132-141 ◽  
Author(s):  
Jong-Sub Lee ◽  
Jung Uk Song ◽  
Won-Taek Hong ◽  
Jung-Doung Yu
Keyword(s):  
Time Domain ◽  
Bored Piles ◽  
Time Domain Reflectometer

ABCD Matrix: A Unique Tool for Linear Two-Wire Transmission Line Modelling

2003 ◽  
Vol 40 (3) ◽  
pp. 220-229 ◽  
Author(s):  
Pedro L. D. Peres ◽  
Carlos R. de Souza ◽  
Ivanil S. Bonatti
Keyword(s):  
Differential Equations ◽  
Transmission Line ◽  
Frequency Domain ◽  
Transmission Lines ◽  
Time Domain ◽  
Mathematical Concepts ◽  
Frequency Dependent ◽  
Abcd Matrix ◽  
The Time Domain

The aim of this note is to show that all the behaviour of a two-wire transmission line can be directly derived from the application of ABCD matrix mathematical concepts, avoiding the explicit use of differential equations. An important advantage of this approach is that the transmission line modelling arises naturally in the frequency domain. Therefore the consideration of frequency-dependent parameters can be carried out in a simple way compared with the time-domain. Some standard examples of transmission lines are analysed through the use of ABCD matrices and a case study of a balun network is presented.

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