Determination of Acoustic Attenuation in Composites by the Time Frequency Method

2017 ◽  
Vol 103 (6) ◽  
pp. 917-925
Author(s):  
Ngoc Tan Duong ◽  
Jean Duclos ◽  
Pascal Pareige ◽  
André Baillard
Keyword(s):  
Acoustic Attenuation ◽  
Frequency Method ◽  
Time Frequency

scholarly journals Multivariate empirical mode decomposition–based structural damage localization using limited sensors

2021 ◽  
pp. 107754632110069
Author(s):  
Sandeep Sony ◽  
Ayan Sadhu
Keyword(s):  
Empirical Mode Decomposition ◽  
Structural Damage ◽  
Cost Effective ◽  
Threshold Value ◽  
Damage Localization ◽  
Time Frequency ◽  
Multivariate Empirical Mode Decomposition ◽  
Percentage Difference ◽  
Mode Decomposition

In this article, multivariate empirical mode decomposition is proposed for damage localization in structures using limited measurements. Multivariate empirical mode decomposition is first used to decompose the acceleration responses into their mono-component modal responses. The major contributing modal responses are then used to evaluate the modal energy for the respective modes. A damage localization feature is proposed by calculating the percentage difference in the modal energies of damaged and undamaged structures, followed by the determination of the threshold value of the feature. The feature of the specific sensor location exceeding the threshold value is finally used to identify the location of structural damage. The proposed method is validated using a suite of numerical and full-scale studies. The validation is further explored using various limited measurement cases for evaluating the feasibility of using a fewer number of sensors to enable cost-effective structural health monitoring. The results show the capability of the proposed method in identifying as minimal as 2% change in global modal parameters of structures, outperforming the existing time–frequency methods to delineate such minor global damage.

Fuzzified time-frequency method for identification and localization of power system faults

2021 ◽  
pp. 1-13
Author(s):  
Pullabhatla Srikanth ◽  
Chiranjib Koley
Keyword(s):  
Power System ◽  
High Accuracy ◽  
Fuzzy Decision ◽  
Frequency Method ◽  
Time Frequency ◽  
Novel Approach ◽  
S Transform ◽  
Different Types ◽  
Power System Faults ◽  
Frequency Magnitude

In this work, different types of power system faults at various distances have been identified using a novel approach based on Discrete S-Transform clubbed with a Fuzzy decision box. The area under the maximum values of the dilated Gaussian windows in the time-frequency domain has been used as the critical input values to the fuzzy machine. In this work, IEEE-9 and IEEE-14 bus systems have been considered as the test systems for validating the proposed methodology for identification and localization of Power System Faults. The proposed algorithm can identify different power system faults like Asymmetrical Phase Faults, Asymmetrical Ground Faults, and Symmetrical Phase faults, occurring at 20% to 80% of the transmission line. The study reveals that the variation in distance and type of fault creates a change in time-frequency magnitude in a unique pattern. The method can identify and locate the faulted bus with high accuracy in comparison to SVM.

Double-frequency method for determination of the parameters of SMBS gain spectrum

2013 ◽  
Author(s):  
Anvar A. Talipov ◽  
Alexander A. Vasilets ◽  
Oleg G. Morozov
Keyword(s):  
Gain Spectrum ◽  
Frequency Method ◽  
Double Frequency

IDENTIFICATION OF IMPACT FORCE ON THE GAS PIPE BASED ON ANALYSIS OF THE ACOUSTIC WAVE

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1039-1044 ◽  
Author(s):  
MIN-SOO KIM ◽  
SANG-KWON LEE ◽  
SUNG-JONG KIM
Keyword(s):  
Acoustic Wave ◽  
Cavity Mode ◽  
Impact Force ◽  
Correlation Technique ◽  
Frequency Method ◽  
Time Frequency ◽  
Long Time ◽  
Mode Characteristics ◽  
The Impact ◽  
The Waves

An acoustic wave signal measured on the gas pipe due to impact force is transfer to the far distance through the medium inside of duct. This signal is very complex since it includes the acoustic wave and solid wave. Acoustic wave is affected by the cavity mode inside of duct. The analysis of this acoustic wave gives information about the impact force. For the analysis of this signal, the correlation technique has been used for a long time. This method has a limitation for the application since the waves have dispersive and cavity mode characteristics for the flexible wave. In this paper, we present the time-frequency method for the identification of impact force and the location of impact on the gas pipe. The results give the useful information for the impact force and are applied to the analysis of leakage location of the gas pipe.

Rapid determination of water in benzoyl peroxide by high frequency method

1973 ◽  
Vol 22 (11) ◽  
pp. 1440-1445
Author(s):  
Yuichi KAMURA ◽  
Sabro MIZUTANI ◽  
Keiko TOMIHISA ◽  
Masakazu SUGIYAMA
Keyword(s):  
Benzoyl Peroxide ◽  
High Frequency ◽  
Rapid Determination ◽  
Frequency Method

Time-Frequency Analysis Method in the Transient Power Quality Disturbance Analysis Application

2014 ◽  
Vol 700 ◽  
pp. 99-102
Author(s):  
Meng Da Li ◽  
Yu Bo Duan ◽  
Yan Wang
Keyword(s):  
Power Quality ◽  
Signal Interference ◽  
Time Frequency ◽  
Quality Signal ◽  
Power Quality Disturbance ◽  
Analysis Application ◽  
Disturbance Analysis ◽  
Realistic Significance ◽  
Transient Power Quality

This paper uses the method of S transformation to test the starting time, the end of the time, frequency and amplitude characteristics of common transient power quality signal disturbance. Through error analysis and simulation show that this method can accurately determine the disturbance occurred time and duration, and the identification and determination of disturbance can be simple and intuitive. It has the practical value and realistic significance to power quality signal interference analysis.

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