Deformation Monitoring Data De-Noising Processing Based on Wavelet Packet

2012 ◽  
Vol 166-169 ◽  
pp. 1180-1186 ◽  
Author(s):  
Yan Mei Yang ◽  
Ze Gen Wang ◽  
Yu Yun Gao ◽  
Fa Peng Gao
Keyword(s):  
Wavelet Packet ◽  
Low Frequency ◽  
Deformation Monitoring ◽  
Monitoring Data ◽  
Local Analysis ◽  
Landslide Monitoring ◽  
Minimum Entropy ◽  
Mathematical Methods ◽  
Lower Amplitude ◽  
Unbiased Risk

Wavelet packet coefficients carrying real signals have large amplitude but are in minority, while those carrying noise has lower amplitude but is of large number. In this case, the Basic principle of de-noising wavelet packet is to process signals carrying noise. A suitable threshold is chosen in different decomposition level. Wavelet packet coefficient of less than this threshold is set to equal zero, while wavelet packet coefficients of greater than this threshold is reserved and reconstructed into de-noising signals. MSE, SNR, PSNR are regarded as the standards of de-noising evaluation, some mathematical methods such as Shannon entropy, norm entropy, logarithm energy entropy, threshold entropy, Stein Unbiased Risk Estimate entropy are adopted to measure whether the wavelet packet basis is optimal , minimum Entropy function D value is the best base. Selecting threshold and threshold quantitative is the key to wavelet packet de-noising. And selection of threshold value abides standards such as Sqtwolog, Rigrsure, Heursure, Manimaxi, or Birge-massart. Wavelet packet de-noising method has been applied to tunnel vault sink and landslide monitoring data de-noising processing, which manifests itself being a more elaborate, flexible method compared to wavelet de-noising, since wavelet packet de-noising can even subdivided the low-frequency part and the high-frequency part of upper layer, thus entertains a more precise local analysis capabilities.

Research of Wavelet Packet Analysis in the De-Noising of Ultrasonic Echo Signal

2011 ◽  
Vol 403-408 ◽  
pp. 1817-1822
Author(s):  
Xi Feng Zhou ◽  
Xiao Wu ◽  
Qian Gang Guo
Keyword(s):  
Signal To Noise Ratio ◽  
Wavelet Packet ◽  
Random Noise ◽  
Flaw Detection ◽  
Low Frequency ◽  
Local Analysis ◽  
Echo Signal ◽  
Wavelet Packet Analysis ◽  
Ultrasonic Flaw

The quality of ultrasonic flaw echo signal is the foundation of achieving qualitative and quantitative analysis in the in ultrasonic flaw detection. In practice, the flaw echo signals are often contaminated or even annihilation by random noise. According to the characteristics of ultrasonic flaw echo signal, wavelet packet has more accurate local analysis ability in low frequency and high frequency part. This paper discusses de-noising in ultrasonic signals based on wavelet packet analysis, and proposes an improved threshold approach for de-noising. The results show that: It remarkably raises the signal-to-noise ratio of ultrasonic flaw echo signal and improves the quality of signal with improved wavelet packet threshold.

scholarly journals Multi-modal Landslide Monitoring Data Fusion Algorithm Based on Resistivity Imaging

2021 ◽  
Author(s):  
Haning Xu ◽  
Juzhi Deng ◽  
Xiaoqing Xu ◽  
Jian Zhang ◽  
Gang Li ◽  
...  
Keyword(s):  
Deformation Process ◽  
Deformation Monitoring ◽  
Monitoring Data ◽  
Landslide Monitoring ◽  
Layer By Layer ◽  
Semantic Matching ◽  
Imaging Data ◽  
Fusion Algorithm ◽  
Modal Data ◽  
Resistivity Imaging

Abstract In the process of landslide deformation monitoring, the indicators of monitoring system based on surface displacement cannot accurately reflect the deformation evolution law of deep geotechnical body. Although the joint time curve of deep displacement monitoring of borehole and related monitoring data can reflect the deformation characteristics inside the slope body, it cannot spatially describe and explain the overall deformation process of geotechnical body completely due to the limitation of technical conditions such as borehole. In this paper, using the characteristics of resistivity imaging technology with fast and accurate collection of electrical information of subsurface medium and multi-dimensional imaging, we take resistivity imaging data as complete modal data and fuse deep displacement and groundwater level and other modal data. Through joint depth matrix decomposition and optimization, layer-by-layer modal semantic matching and updating, the distribution and representation differences of modal data are compensated, and the analysis tasks such as classification and clustering of incomplete multimodal data are completed, and the inversion results of resistivity data are updated according to the output modal shared eigenvalues to realize effective multidimensional imaging monitoring of the internal deformation process of landslide geological bodies.

scholarly journals Denoising GPS-Based Structure Monitoring Data Using Hybrid EMD and Wavelet Packet

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Lu Ke
Keyword(s):  
High Frequency ◽  
Wavelet Packet ◽  
Low Frequency ◽  
Monitoring Data ◽  
Intrinsic Mode Functions ◽  
Mode Decomposition ◽  
Structure Monitoring ◽  
Energy Leakage ◽  
Frequency Components ◽  
Different Characteristics

High-frequency components are often discarded for data denoising when applying pure wavelet multiscale or empirical mode decomposition (EMD) based approaches. Instead, they may raise the problem of energy leakage in vibration signals. Hybrid EMD and wavelet packet (EMD-WP) is proposed to denoise Global Positioning System- (GPS-) based structure monitoring data. First, field observables are decomposed into a collection of intrinsic mode functions (IMFs) with different characteristics. Second, high-frequency IMFs are denoised using the wavelet packet; then the monitoring data are reconstructed using the denoised IMFs together with the remaining low-frequency IMFs. Our algorithm is demonstrated on a synthetic displacement response of a 3-story frame excited by El Centro earthquake along with a set of Gaussian random white noises on different levels added. We find that the hybrid method can effectively weaken the multipath effect with low frequency and can potentially extract vibration feature. However, false modals may still exist by the rest of the noise contained in the high-frequency IMFs and when the frequency of the noise is located in the same band as that of effective vibration. Finally, real GPS observables are implemented to evaluate the efficiency of EMD-WP method in mitigating low-frequency multipath.

A Novel Fault-location Method for HVDC Transmission Lines Based on Concentric Relaxation Principle and Wavelet Packet

2020 ◽  
Vol 13 (5) ◽  
pp. 705-716
Author(s):  
Congshan Li ◽  
Ping He ◽  
Feng Wang ◽  
Cunxiang Yang ◽  
Yukun Tao ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Traveling Wave ◽  
Fault Location ◽  
Wave Attenuation ◽  
Wavelet Packet ◽  
Low Frequency ◽  
Evaluation Process ◽  
Location Method ◽  
Hvdc Transmission ◽  
Instantaneous Energy

Background: A novel fault location method of HVDC transmission line based on a concentric relaxation principle is proposed in this paper. Methods: Due to the different position of fault, the instantaneous energy measured from rectifier and inverter are different, and the ratio k between them is the relationship to the fault location d. Through the analysis of amplitude-frequency characteristics, we found that the wave attenuation characteristic of low frequency in the traveling wave is stable, and the amplitude of energy is larger, so we get the instantaneous energy ratio by using the low-frequency data. By using the method of wavelet packet decomposition, the voltage traveling wave signal was decomposed. Results: Finally, calculate the value k. By using the data fitting, the relative function of k and d can be got, that is the fault location function. Conclusion: After an exhaustive evaluation process considering different fault locations, fault resistances, and noise on the unipolar DC transmission system, four-machine two-area AC/DC parallel system, and an actual complex grid, the method presented here showed a very accurate and robust behavior.

scholarly journals Slithering CSF: Cerebrospinal Fluid Dynamics in the Stationary and Moving Viper Boa, Candoia aspera

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 672
Author(s):  
Bruce A. Young ◽  
Skye Greer ◽  
Michael Cramberg
Keyword(s):  
Cerebrospinal Fluid ◽  
Cardiac Cycle ◽  
Low Frequency ◽  
Mean Amplitude ◽  
The Body ◽  
Body Waves ◽  
Lower Amplitude ◽  
Lateral Undulation ◽  
Recovery From Anesthesia ◽  
The Relationship

In the viper boa (Candoia aspera), the cerebrospinal fluid (CSF) shows two stable overlapping patterns of pulsations: low-frequency (0.08 Hz) pulses with a mean amplitude of 4.1 mmHg that correspond to the ventilatory cycle, and higher-frequency (0.66 Hz) pulses with a mean amplitude of 1.2 mmHg that correspond to the cardiac cycle. Manual oscillations of anesthetized C. aspera induced propagating sinusoidal body waves. These waves resulted in a different pattern of CSF pulsations with frequencies corresponding to the displacement frequency of the body and with amplitudes greater than those of the cardiac or ventilatory cycles. After recovery from anesthesia, the snakes moved independently using lateral undulation and concertina locomotion. The episodes of lateral undulation produced similar influences on the CSF pressure as were observed during the manual oscillations, though the induced CSF pulsations were of lower amplitude during lateral undulation. No impact on the CSF was found while C. aspera was performing concertina locomotion. The relationship between the propagation of the body and the CSF pulsations suggests that the body movements produce an impulse on the spinal CSF.

Ultrasonic Transceiver-Based Structural Deformation Monitoring with Location Ability

2014 ◽  
Vol 721 ◽  
pp. 442-445
Author(s):  
Wei Zheng ◽  
Chun Xian Wu ◽  
Rong Rong Cui
Keyword(s):  
Spatial Relations ◽  
Deformation Monitoring ◽  
Monitoring Data ◽  
Structural Deformation ◽  
Monitoring Method ◽  
Regional Monitoring ◽  
Space Deformation ◽  
Structural Surface

Regional coverage monitoring for structural deformation remains a challenge for current technologies. A coverage regional monitoring method based on dual ultrasonic transceivers and exhibiting deformation location ability is presented. The spatial projecting model of dual ultrasonic beams is established to determine the monitoring scope of the structural surface in space. Deformation location principles are induced by analyzing the spatial relations of the monitoring data of dual ultrasonic transceivers. Finally, an experiment is proposed to illustrate the method.

Deformation Monitoring and Data Analysis for Metro Construction with Mining Method in Dalian

2013 ◽  
Vol 353-356 ◽  
pp. 1604-1608
Author(s):  
Guang Bin Bai ◽  
Jie Zhao ◽  
Li Sheng Liu
Keyword(s):  
Data Analysis ◽  
Construction Method ◽  
Deformation Monitoring ◽  
Monitoring Data ◽  
Ground Subsidence ◽  
Tunnel Construction ◽  
Mining Method ◽  
Construction Process ◽  
Subway Tunnel ◽  
The Future

Based on a subway tunnel construction, the construction method was introduced. The ground subsidence, crown settlement and convergence displacement caused by the cut tunnel are monitored during the tunneling construction and the results of monitoring data for them are analyzed. This technology wells to guide the tunnel-entering construction effectively and avoid the tunnel-entering construction process prone to landslides, thus ensuring the safety of the tunnel construction and will guiding the future construction.

Knowledge-guided consistent correlation analysis of multimode landslide monitoring data

2017 ◽  
Vol 31 (11) ◽  
pp. 2255-2271
Author(s):  
Shuangxi Miao ◽  
Qing Zhu ◽  
Bo Zhang ◽  
Yuling Ding ◽  
Junxiao Zhang ◽  
...  
Keyword(s):  
Correlation Analysis ◽  
Monitoring Data ◽  
Landslide Monitoring

scholarly journals Experimental Study on Deformation Monitoring of Bored Pile Based on BOTDR

2019 ◽  
Vol 9 (12) ◽  
pp. 2435 ◽  
Author(s):  
Lei Gao ◽  
Chuan Han ◽  
Zhongquan Xu ◽  
Yingjie Jin ◽  
Jianqiang Yan
Keyword(s):  
Optical Fiber ◽  
Noise Removal ◽  
Deformation Monitoring ◽  
Optical Time Domain Reflectometer ◽  
Fiber Sensing ◽  
Bored Pile ◽  
Sensing Technology ◽  
Optical Fiber Sensing ◽  
Unbiased Risk ◽  
Distributed Optical Fiber

In order to study the deformation of bored pile, it is necessary to monitor the strain of the pile. The distributed optical fiber sensing technology realizes the integration of sensing and transmission, which is incomparable with traditional point monitoring method. In this paper, the Brillouin optical time domain reflectometer (BOTDR) distributed optical fiber sensing technology is used to monitor the deformation of the bored pile. The raw data monitored by BOTDR is processed by the wavelet basis function, that can perform noise removal processing. Three different methods of noise removal are chosen. Through the processing, the db5 wavelet is used to decompose the deformation data of bored pile monitored by BOTDR into two layers. The decomposed high-frequency signal is denoised by the Stein-based unbiased risk threshold, rigrsure. The decomposed data is smoothed by the translational mean method, and the final data after denoising and smoothing processing is real and reliable. The results of this study will provide data support for the deformation characteristics of bored pile, and also show the advantages of distributed optical fiber sensing technology.

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