Understanding the guided waves propagation behavior in timber utility poles

2020 ◽  
Vol 10 (5) ◽  
pp. 793-813 ◽  
Author(s):  
Jad El Najjar ◽  
Samir Mustapha
2021 ◽  
Author(s):  
Geng Wang ◽  
Zhonglei Gao ◽  
Mingyu Wu ◽  
Guoqiang Wang ◽  
Sudong Xiao ◽  
...  

Abstract Electromagnetic ion cyclotron (EMIC) waves can cause the scattering loss of the relativistic electrons in the earth's radiation belt. They can be classified into the guided mode and the unguided mode, according to waves propagation behavior. The guided mode waves have been widely investigated in the radiation belt, but the observation of the unguided mode waves have not been expected. Based on the observations of Van Allen Probes, we demonstrate for the first time the existence of the intense unguided mode EMIC waves. The reflection interface formed by the spatial locations of local helium cutoff frequencies can be nearly parallel to the equatorial plane when the proton abundance ratio decreases sharply with L-shell. This structure combined with the anisotropic hot protons can lead to the trapping and significant amplification of the unguided mode waves. These results may help to understand the nature of EMIC waves in the radiation belt.


2020 ◽  
Vol 20 (10) ◽  
pp. 2042002 ◽  
Author(s):  
Yang Yu ◽  
Mahbube Subhani ◽  
Azadeh Noori Hoshyar ◽  
Jianchun Li ◽  
Huan Li

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.


PAMM ◽  
2010 ◽  
Vol 10 (1) ◽  
pp. 501-502
Author(s):  
Dmitry Zakharov ◽  
Alexandr Kaptsov

2016 ◽  
Vol 139-140 ◽  
pp. 250-255 ◽  
Author(s):  
Minxin Qi ◽  
Shaoping Zhou ◽  
Jing Ni ◽  
Yong Li

2019 ◽  
Vol 957 ◽  
pp. 329-339
Author(s):  
A. de Luca ◽  
Donato Perfetto ◽  
Francesco Caputo

Thanks to their high damage detection sensitivity and low requested power consumption, guided-waves (Lamb waves) have been increasingly used in the last years to monitor the structural integrity in primary and secondary composite structures. The monitoring of the structural health through the propagation of Lamb waves in composite structures is notoriously complex and, for this reason, the development of a prediction model can be a helpful tool for the improvement of Structural Health Monitoring (SHM) systems. Finite Element Method (FE) appears to be the best candidate for such type of simulation. However, since Lamb waves propagation depends strictly on the local material properties of the medium they propagate through, their numerical characterization is a thorny phase. Real composite components are usually affected by the presence of a large number of voids and defects, which cannot be reproduced in numerical models; this leads to a variability of the mechanical properties of materials, with particular reference to elastic moduli and density. These aspects get really ambitious the development of a well-established FE model. In this paper, a design of experiment (DOE) has been carried out to numerically investigate on the effects of the material properties variability on guided-waves time of flight.


2021 ◽  
Vol 184 ◽  
pp. 108356
Author(s):  
Gao Jie ◽  
Lyu Yan ◽  
Zheng Mingfang ◽  
Liu Mingkun ◽  
Liu Hongye ◽  
...  

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