Automatic defect recognition for pulsed terahertz inspection of basalt fiber reinforced composites

2016 ◽  
Vol 35 (4) ◽  
pp. 1346-1359 ◽  
Author(s):  
Przemyslaw Lopato
Keyword(s):  
Electromagnetic Waves ◽  
Dielectric Material ◽  
Conductive Polymer ◽  
Basalt Fiber ◽  
Principal Component ◽  
Dielectric Materials ◽  
Fiber Reinforced ◽  
Content Type ◽  
Non Destructive Evaluation ◽  
Non Destructive

Purpose – The purpose of this paper is to present a system for automatic recognition of defects detected in non-conductive polymer composites using pulsed terahertz imaging. Design/methodology/approach – On the beginning, non-destructive evaluation of composites using electromagnetic waves in terahertz frequency is shortly introduced. Next automatic defects recognition (ADR) algorithm is proposed, focussing on new features calculation. Dimensionality of features space is reduced by using principal component analysis. Finally, results of basalt fiber reinforced composite materials inspection and identification using artificial neural networks is presented and discussed. Findings – It is possible to develop ADR system for non-destructive evaluation of dielectric materials using pulsed terahertz technique. New set of features in time and frequency domains is proposed and verified. Originality/value – ADR in non-destructive testing is utilized in case of digital radiography and ultrasonic testing. Terahertz inspection with pulsed excitation is reported as a source of many useful information about the internal structure of the dielectric material. Up to now ADR based on terahertz non-destructive evaluation systems was not utilized.

scholarly journals Automated Health Condition Diagnosis of in situ Wood Utility Poles Using an Intelligent Non-Destructive Evaluation (NDE) Framework

2020 ◽  
Vol 20 (10) ◽  
pp. 2042002 ◽  
Author(s):  
Yang Yu ◽  
Mahbube Subhani ◽  
Azadeh Noori Hoshyar ◽  
Jianchun Li ◽  
Huan Li
Keyword(s):  
Communication Networks ◽  
Guided Waves ◽  
Power Transmission ◽  
Influence Factors ◽  
Principal Component ◽  
Field Testing ◽  
Health Condition ◽  
Non Destructive Evaluation ◽  
Utility Poles ◽  
Non Destructive

Wood utility poles are widely applied in power transmission and telecommunication systems in Australia. Because of a variety of external influence factors, such as fungi, termite and environmental conditions, failure of poles due to the wood degradation with time is of common occurrence with high degree uncertainty. The pole failure may result in serious consequences including both economic and public safety. Therefore, accurately and timely identifying the health condition of the utility poles is of great significance for economic and safe operation of electricity and communication networks. In this paper, a novel non-destructive evaluation (NDE) framework with advanced signal processing and artificial intelligence (AI) techniques is developed to diagnose the condition of utility pole in field. To begin with, the guided waves (GWs) generated within the pole is measured using multi-sensing technique, avoiding difficult interpretation of various wave modes which cannot be detected by only one sensor. Then, empirical mode decomposition (EMD) and principal component analysis (PCA) are employed to extract and select damage-sensitive features from the captured GW signals. Additionally, the up-to-date machine learning (ML) techniques are adopted to diagnose the health condition of the pole based on selected signal patterns. Eventually, the performance of the developed NDE framework is evaluated using the field testing data from 15 new and 24 decommissioned utility poles at the pole yard in Sydney.

scholarly journals Investigation of the parameters of the reflected wave near the Brewster angle

2021 ◽  
Vol 2140 (1) ◽  
pp. 012026
Author(s):  
V P Krylov
Keyword(s):  
Electromagnetic Waves ◽  
Dielectric Material ◽  
Angular Position ◽  
Experimental Studies ◽  
Dielectric Materials ◽  
Brewster Angle ◽  
Magnetic Losses ◽  
Geometric Optics ◽  
Phase Jump ◽  
Reflected Wave

Abstract In free space, the relative permittivity is determined by the Brewster formula without taking into account dielectric and magnetic losses. In experimental studies, discrepancies in the angular position of the minimum of the reflected wave from dielectric materials are observed in comparison with calculations, which are known as deviations from Fresnel’s laws. By solving the task of inclined falling wave on an plate made of a dielectric material with complex of the dielectric and magnetic permittivity, the parameters of the reflected wave were calculated, according to which the angles corresponding to the minimum reflection were determined, depending on the dielectric losses of the material. From the condition that the reflected wave is equal to zero, a formula for determining the Brewster angle for a material with dielectric and magnetic losses was analytically obtained, the results of calculations for which coincided with the calculations for the reflected wave in the context of geometric optics. It is determined that in the general case, the conditions for determining the position of the minimum of the complex amplitude and the phase jump by 180° of electromagnetic waves do not coincide and can be found only when solving the task an falling wave on a plate with complex electrodynamic parameters of the material in the context of geometric optics.

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