Damage alarming analysis for ancient wood structures based on wavelet packet energy spectrum

2014 ◽  
Vol 10 (4) ◽  
pp. 593-610 ◽  
Author(s):  
Xin Wang ◽  
Wei Bing Hu ◽  
Zhao Bo Meng
Keyword(s):  
Energy Spectrum ◽  
White Noise ◽  
Wavelet Packet ◽  
Energy Ratio ◽  
Noise Robustness ◽  
Wood Structures ◽  
Content Type ◽  
Bell Tower ◽  
Ancient Wood ◽  
Damage Alarming

Purpose – The purpose of this paper is to establish the damage alarming indexes for ancient wood structures and study the damage sensitivity and noise robustness of these indexes under random excitation. Design/methodology/approach – Xi’an Bell Tower is taken as a case in this paper to simulate the damage of ancient wood structures through finite element (FE) simulation and determine the satisfactory damage alarming indexes with wavelet packet energy spectrum. Findings – The results of this paper show that: 1) the damage alarming indexes can effectively identify the damage of ancient wood structures, each index with a different damage sensitivity; 2) the energy ratio deviation is greater than the energy ratio variance and is close to the maximum variation of energy ratio; 3) the energy ratio deviation has a better alarming effect than the energy ratio variance during the initial period of the damage. With the accumulation of the damage, the energy ratio variance outperforms the energy ratio deviation; 4) the sensitivity of the energy ratio deviation and variance varies from positions, changing from the highest to lowest at the mortise-and-tenon joints, the beam mid-span and the plinth; 5) if signal to noise ratio (SNR) is 40db or larger, the indexes can accurately identify the damage of ancient wood structures. As SNR increases, the indexes will have an increasingly higher sensitivity and certain ability to resist noise. Research limitations/implications – The FE model is simpiy, it does not completely reflect Xi’an Bell Tower. Practical implications – It will provide a theoretical basis for the damage alarming of Xi’an Bell Tower. Social implications – It makes structural health monitoring through structural vibration response under ambient excitation a new research field in damage detection as well as a positive way of ancient architecture protection. Originality/value – This paper studies the damage alarming effect on ancient wood structures from different wavelet functions and wavelet packet decomposition levels. To study the effect under white noise environment, this paper adds Gaussian white noise with a SNR of 10, 20, 30, 40 and 50 db to the acceleration response signal of intact structure and damaged structure.

Study on Parameters for Identification of Wavelet Packet Energy Spectrum for Structural Damage Alarming

2010 ◽  
Vol 163-167 ◽  
pp. 2693-2698 ◽  
Author(s):  
Peng Sun ◽  
Ai Qun Li ◽  
You Liang Ding ◽  
Yang Deng
Keyword(s):  
Experimental Data ◽  
Energy Spectrum ◽  
Structural Damage ◽  
Online Monitoring ◽  
Wavelet Packet ◽  
Suspension Bridge ◽  
Frame Structure ◽  
Daubechies Wavelet ◽  
Damage Alarming ◽  
Steel Frame Structure

The damage alarming analysis based on wavelet packet energy spectrum is performed with regard to the experimental data of Benchmark steel frame structure and online monitoring data of Runyang Suspension Bridge, on the basis of which the damage alarming effects using various wavelet functions are investigated in detail. Results reveal that the Daubechies wavelet functions and Coiflets wavelet functions are applicable to structural damage alarming.

Application of Wavelet Packet Analysis in Damage Alarming for Steel-Frame Structure

2012 ◽  
Vol 204-208 ◽  
pp. 2883-2886
Author(s):  
Ning Zhang ◽  
Zhuo Bin Wei ◽  
Zi Wang ◽  
Sen Wu
Keyword(s):  
Energy Spectrum ◽  
Response Function ◽  
Damage Identification ◽  
Wavelet Packet ◽  
Impulse Response Function ◽  
Steel Frame ◽  
Frame Structure ◽  
Wavelet Packet Analysis ◽  
Damage Alarming ◽  
Steel Frame Structure

The method of damage alarming based on wavelet packet analysis which applied on steel-frame structure is researched. Firstly, the method of damage identification based on wavelet packet analysis is introduced. Secondly, in view of the dependability of the method on the excitation, virtual impulse response function is brought in to enhance robustness of the method to the excitation. Lastly, through the steel-frame structure experimentation of damage alarming, the two damage modes of the structure are identified by the method based on wavelet packet energy spectrum. The experimentation results show that the effect of damage alarming to the steel-frame structure is completely obvious by wavelet packet analysis. Accordingly, this method has much application value for engineering.

scholarly journals Experimental study of grout defect identification in precast column based on wavelet packet analysis

2019 ◽  
Vol 15 (11) ◽  
pp. 155014771988959
Author(s):  
Xuan Zhang ◽  
Deyuan Zhou ◽  
Hesheng Tang ◽  
Xiao Han
Keyword(s):  
Energy Transfer ◽  
Energy Spectrum ◽  
Wavelet Packet ◽  
Precast Concrete ◽  
Energy Ratio ◽  
Combination Method ◽  
Wavelet Packet Analysis ◽  
Average Deviation ◽  
Defect Identification ◽  
Ratio Variation

Grout defects always exist in sleeves of precast structures, but studies on grout defect identification are rarely performed. This article proposes a combination method of dynamic excitation technique and wavelet packet analysis for sleeve defect identification in the precast structure. Hammer excitation on a 1/2-scaled two-floor precast concrete frame structure with column rebar splicing by grout sleeves is conducted to collect column acceleration responses. Moreover, the corresponding energy spectrum is obtained by the wavelet packet analysis. Furthermore, three defect identification indices, that is, percentage of energy transfer, energy ratio variation deviation, and energy spectrum average deviation, are calculated and compared. Robustness analysis of the energy ratio variation deviation is carried out by adding white noise in the original acceleration response signals. The results show that (1) the percentage of energy transfer, the energy ratio variation deviation, and the energy spectrum average deviation are positively correlated with the grout defect degree where the energy ratio variation deviation is more sensitive in the identification of defects; (2) the energy ratio variation deviation robustness of the original signal with the inputted multiplicative white Gaussian noises is better than that with the inputted additive white Gaussian noise; and (3) the proposed defect identification method can characterize the sleeve grout defect degree in column.

scholarly journals The problem of “white noise”: examining current prevention approaches to online fraud

2016 ◽  
Vol 23 (4) ◽  
pp. 806-818 ◽  
Author(s):  
Cassandra Cross ◽  
Michael Kelly
Keyword(s):  
White Noise ◽  
Personal Information ◽  
Large Degree ◽  
Black Book ◽  
Content Type ◽  
Online Fraud ◽  
Police Investigation ◽  
Multiple Data ◽  
Prevention Messages ◽  
Practical Implications

Purpose The purpose of this paper is to examine the current prevention messages that exist surrounding the prevention of online fraud. In particular, it focuses on the amount and level of detail that is promoted for each type of potential fraudulent approach. Design/methodology/approach Multiple data sources are used to establish the main premise of this paper. This includes the publication entitled The Little Black Book of Scams, qualitative data from victims who have experienced online fraud, and materials collected through a police investigation into online fraud. Findings Results of this analysis indicate that current prevention messages are characterised by a large degree of detail about the various ways that (online) fraud can be perpetrated. This is argued to be ineffective, based on the experiences of victims who were unable to apply their previous knowledge about fraud to their experiences. Additionally, the categorisation of fraudulent approaches is highlighted as unimportant to offenders, who are focused on obtaining money by whatever means (or approach) possible. Practical implications This paper provides the impetus to evaluate the effectiveness of current prevention messages. It points to a simplification of existing prevention messages to focus more importantly on the transfer of money and the protection of personal information. Originality/value This paper argues that current prevention messages are characterised by too much “white noise”, in that they focus on an overwhelming amount of detail. This is argued to obscure what should be a straightforward message which could have a greater impact than current messages.

Seeking rhythm in white noise: working with whiteness in English education

2017 ◽  
Vol 16 (1) ◽  
pp. 40-54 ◽  
Author(s):  
Samuel Jaye Tanner ◽  
Christina Berchini
Keyword(s):  
Narrative Inquiry ◽  
White Noise ◽  
Language Arts ◽  
Teaching And Learning ◽  
Design Methodology ◽  
English Language ◽  
English Education ◽  
White People ◽  
Content Type ◽  
White Resistance

Purpose The authors of this paper are both white English education scholars with antiracist agendas. This conceptual manuscript aims – in part – to better understand the backlash both of them have faced in trying to contribute to antiracist teaching and research in English education. Design/methodology/approach This manuscript uses practices of narrative inquiry to tell and interpret stories about the authors’ work. Findings The authors hope to critique traditional notions of white resistance in favor of more careful theorizations of whiteness that can be helpful for teachers and scholars in English education and English Language Arts (ELA)with an interest in facilitation antiracist pedagogy. Originality/value Ultimately, with this work, the authors hope to provoke readers to consider how work with whiteness is processed by white people, especially in terms of teaching and learning in English education and ELA. They believe the field of English education should begin to discuss this issue.

Research on the Imbalance-Crack Coupling Fault Diagnosis Based on Wavelet Packet and Energy Spectrum Analysis

2011 ◽  
Vol 143-144 ◽  
pp. 675-679 ◽  
Author(s):  
Fu Ze Xu ◽  
Xue Jun Li ◽  
Guang Bin Wang ◽  
Da Lian Yang
Keyword(s):  
Mechanical Properties ◽  
Fault Diagnosis ◽  
Energy Spectrum ◽  
Spectrum Analysis ◽  
Wavelet Packet ◽  
Rotating Machinery ◽  
Vibration Acceleration ◽  
Acceleration Signal ◽  
Coupling Fault ◽  
Fault Information

It is common for the imbalance-crack coupling fault in rotating machinery, while the crack information is often overshadowed by unbalanced fault information, which is difficult to extract the crack signal. In order to extract the crack signal of the imbalance-crack coupling fault, and realize the fault diagnosis, the paper mainly analyzes its mechanical properties, and then use wavelet packet to de-nosing, decomposing and reconstructing the acquisition of vibration acceleration signal, and then analyzing the characteristics of frequency domain of the fault signal by using the energy spectrum. So the experiment proved that analyze and dispose the acquisition of the fault signal by using the method of the energy spectrum and the wavelet packet, which can effectively distinguish between the crack signal and unbalanced signals in imbalance-crack coupling faults .It also can provide some reference for the diagnosis and prevention for such fault.

The mixing layer and its coherence examined from the point of view of two-dimensional turbulence

1988 ◽  
Vol 192 ◽  
pp. 511-534 ◽  
Author(s):  
Marcel Lesieur ◽  
Chantal Staquet ◽  
Pascal Le Roy ◽  
Pierre Comte
Keyword(s):  
Energy Spectrum ◽  
Kinetic Energy ◽  
White Noise ◽  
Mixing Layer ◽  
Finite Size ◽  
Spanwise Direction ◽  
Computational Domain ◽  
Two Dimensional ◽  
Infinite Domain ◽  
Kinetic Energy Spectrum

A two-dimensional numerical large-eddy simulation of a temporal mixing layer submitted to a white-noise perturbation is performed. It is shown that the first pairing of vortices having the same sign is responsible for the formation of a continuous spatial longitudinal energy spectrum of slope between k−4 and k−3. After two successive pairings this spectral range extends to more than 1 decade. The vorticity thickness, averaged over several calculations differing by the initial white-noise realization, is shown to grow linearly, and eventually saturates. This saturation is associated with the finite size of the computational domain.We then examine the predictability of the mixing layer, considering the growth of decorrelation between pairs of flows differing slightly at the first roll-up. The inverse cascade of error through the kinetic energy spectrum is displayed. The error rate is shown to grow exponentially, and saturates together with the levelling-off of the vorticity thickness growth. Extrapolation of these results leads to the conclusion that, in an infinite domain, the two fields would become completely decorrelated. It turns out that the two-dimensional mixing layer is an example of flow that is unpredictable and possesses a broadband kinetic energy spectrum, though composed mainly of spatially coherent structures.It is finally shown how this two-dimensional predictability analysis can be associated with the growth of a particular spanwise perturbation developing on a Kelvin-Helmholtz billow: this is done in the framework of a one-mode spectral truncation in the spanwise direction. Within this analogy, the loss of two-dimensional predictability would correspond to a return to three-dimensionality and a loss of coherence. We indicate also how a new coherent structure could then be recreated, using an eddy-viscosity assumption and the linear instability of the mean inflexional shear.

scholarly journals Damage Identification Investigation of Retaining Wall Structures Based on a Virtual Impulse Response Function

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Qian Xu
Keyword(s):  
Impulse Response ◽  
Response Function ◽  
Frequency Band ◽  
Damage Identification ◽  
Wavelet Packet ◽  
Retaining Wall ◽  
Damage Index ◽  
Impulse Response Function ◽  
Energy Ratio ◽  
Wall Structures

To eliminate the influence of excitation on the wavelet packet frequency band energy spectrum (ES), ES is acquired via wavelet packet decomposition of a virtual impulse response function. Based on ES, a character frequency band vector spectrum and damage eigenvector spectrum (DES) are created. Additionally, two damage identification indexes, the energy ratio standard deviation and energy ratio variation coefficient, are proposed. Based on the damage index, an updated damage identification method for retaining wall structures is advanced. The damage state of a retaining wall can be diagnosed through DES, the damage location can be detected through the damage index trend surface, and the damage intensity can be identified by establishing a quantitative relationship between the damage intensity and damage index. To verify the feasibility and validity of this damage identification method, a vibration test on a pile plate retaining wall is performed. Test results demonstrate that it can distinguish whether the retaining wall is damaged, and the location of partial damage within the retaining wall can be easily detected; in addition, the damage intensity of the wall can also be identified validly. Consequently, this damage identification theory and method may be used to identify damage within retaining wall structures.

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