Chapter 8
Acoustic Emission and Dual-Tree
Complex Wavelet Transform with Soft
Threshold De-Noising to Enhance
Pipeline Leak Detection and Location
L. L. Ting, J. Y. Tey, A. C. Tan, Y. J. King, and F. A. Rahman
Abstract Water leakage control is a subject of growing interest among researchers
and pipeline owners. Various water leak detection methods have been developed and
acoustic leak detection technique has manifested as a decent approach. However, the
demerit of this method is that the collected signal always interferes with noises. This
reduces the accuracy of leak detection and triggers a false alarm. Traditional noise
reduction methods such as digital filtering and wavelet de-noising are not efficient to
eliminate noise from interested signals. To overcome this drawback, an improved denoising method derived from Dual-Tree Complex Wavelet Transform (DTCWT) and
a soft threshold proposed in this paper to reduce the noise and consequently minimize
false trip rate. The signal is decomposed by DTCWT to separate the raw signal into
different frequency bandwidths. Then, soft threshold method is employed to suppress
noise by rescaling the signals which are lower than the prescribed threshold to zero.
Experimental results demonstrate that the proposed de-noising method performs well
than ordinary wavelet de-noising. The accuracy of leak localisation can be increased
by twice. The method accentuates the cross-correlation peak related to the time
delay for leak localization and thereupon increases the accuracy of leak locating.
The proposed method outperforms other methods in term of detectable range of leak
source as it can detect leak up to 24 m whereas the conventional way only can detect
up to 14.5 m.
8.1 Introduction
Water is an important and irreplaceable natural resource. Unfortunately, an abundant
amount of water lost when they are transporting from treatment plants to consumers.
The water lost is classified as non-revenue water (NRW). A statistics provided by
the National Water Services Commission [1] stated that 35.3% of supplied water in
Malaysia consists of NRW which is equals to 5929 million litres per day. The loss
L. L. Ting · J. Y. Tey · A. C. Tan (B) · Y. J. King · F. A. Rahman
Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Selangor,
Malaysia
e-mail: tanacc@utar.edu.my
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
G. Shen et al. (eds.), Advances in Acoustic Emission Technology, Springer Proceedings
in Physics 259, https://doi.org/10.1007/978-981-15-9837-1_8
79
Acoustic Emission and Dual-Tree
Complex Wavelet Transform with Soft
Threshold De-Noising to Enhance
Pipeline Leak Detection and Location
L. L. Ting, J. Y. Tey, A. C. Tan, Y. J. King, and F. A. Rahman
Abstract Water leakage control is a subject of growing interest among researchers
and pipeline owners. Various water leak detection methods have been developed and
acoustic leak detection technique has manifested as a decent approach. However, the
demerit of this method is that the collected signal always interferes with noises. This
reduces the accuracy of leak detection and triggers a false alarm. Traditional noise
reduction methods such as digital filtering and wavelet de-noising are not efficient to
eliminate noise from interested signals. To overcome this drawback, an improved denoising method derived from Dual-Tree Complex Wavelet Transform (DTCWT) and
a soft threshold proposed in this paper to reduce the noise and consequently minimize
false trip rate. The signal is decomposed by DTCWT to separate the raw signal into
different frequency bandwidths. Then, soft threshold method is employed to suppress
noise by rescaling the signals which are lower than the prescribed threshold to zero.
Experimental results demonstrate that the proposed de-noising method performs well
than ordinary wavelet de-noising. The accuracy of leak localisation can be increased
by twice. The method accentuates the cross-correlation peak related to the time
delay for leak localization and thereupon increases the accuracy of leak locating.
The proposed method outperforms other methods in term of detectable range of leak
source as it can detect leak up to 24 m whereas the conventional way only can detect
up to 14.5 m.
8.1 Introduction
Water is an important and irreplaceable natural resource. Unfortunately, an abundant
amount of water lost when they are transporting from treatment plants to consumers.
The water lost is classified as non-revenue water (NRW). A statistics provided by
the National Water Services Commission [1] stated that 35.3% of supplied water in
Malaysia consists of NRW which is equals to 5929 million litres per day. The loss
L. L. Ting · J. Y. Tey · A. C. Tan (B) · Y. J. King · F. A. Rahman
Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Selangor,
Malaysia
e-mail: tanacc@utar.edu.my
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
G. Shen et al. (eds.), Advances in Acoustic Emission Technology, Springer Proceedings
in Physics 259, https://doi.org/10.1007/978-981-15-9837-1_8
79