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Blind pulse compression through skewness maximization on overlapping echoes from thin layers
Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.ORCID iD: 0000-0001-6687-7794
Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.ORCID iD: 0000-0002-6216-6132
Rubico Vibration Analysis AB.
Number of Authors: 32016 (English)In: IEEE Ultrasonics Symposium 2016, Tours France, September 18-21, 2016, Piscataway, NJ: IEEE conference proceedings, 2016, article id 7728571Conference paper, Published paper (Refereed)
##### Abstract [en]

Pulse compression on overlapping echoes without knowledge of the pulse shape, transducer and propagation path impulse response is examined to provide valuable information about the sample structure in ultrasonic testing. A comparison against previous research is presented on two different levels of overlap severity with simulated signals. By exploiting the knowledge on the statistical characteristics of the signal of interest, an appropriate measure of merit, such as skewness, is maximized to promote impulsive occurrences to both extract the excitation signal and to enhance the impulse response of a material under test.

##### Place, publisher, year, edition, pages
Piscataway, NJ: IEEE conference proceedings, 2016. article id 7728571
##### Series
Proceedings - IEEE Ultrasonics Symposium, ISSN 1948-5719
##### Keywords [en]
Dictionary Learning, Acoustic Emission
##### National Category
Signal Processing
##### Research subject
Signal Processing
##### Identifiers
ISI: 000387497400198Scopus ID: 2-s2.0-84996489201Local ID: 67766b7e-31af-44f5-b818-97f7fc13e9fcISBN: 978-1-4673-9897-8 (print)ISBN: 978-1-4673-9898-5 (print)OAI: oai:DiVA.org:ltu-61039DiVA, id: diva2:1055415
##### Conference
IEEE Ultrasonics Symposium 2016, Tours France, September 18-21, 2016
Available from: 2016-12-12 Created: 2016-12-12 Last updated: 2017-12-13Bibliographically approved
##### In thesis
1. Blind Adaptive Extraction of Impulsive Signatures from Sound and Vibration Signals
Open this publication in new window or tab >>Blind Adaptive Extraction of Impulsive Signatures from Sound and Vibration Signals
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
##### Abstract [en]

The two questions in science why" and how" are hereby answered in the context of statistical signal processing applied to vibration analysis and ultrasonic testing for fault detection and characterization in critical materials such as rolling bearings and thin layered media. Both materials are of interest in industrial processes. Therefore, assuring the best operating conditions on rolling bearings and product quality in thin layered materials is important.

The methods defended in this thesis are for retrieval of the impulsive signals arising from such equipments and materials, representing either faults or responses to an excitation. As the measurements collected via sensors usually consist of signals masked by some unknown systems and noise, retrieving the information-rich portion is often challenging. By exploiting the statistical characteristics due to their natural structure, a linear system is designed to recover the signals of interest in different scenarios. Suppressing the undesired components while enhancing the impulsive events by iteratively adapting a filter is the primary approach here. Signal recovery is accomplished by optimizing objectives (skewness and $\ell_1$-norm) quantifying the presumed characteristics, rising the question of objective surface topology and probability of ill convergence. To attack these, mathematical proofs, experimental evidences and comprehensive discussions are presented in the contributions each aiming to answer a specific question.

The aim in the theoretical study is to fill a gap in signal processing by providing analytical and numerical results especially on \emph{skewness} surface characteristics on a signal model (periodic impulses) build on harmonically related sinusoids. With understanding the inner workings and the conditions to suffice, the same approach is applied to different class of signals in ultrasonic testing, such as aperiodic finite energy signals (material impulse response) and a very short duration impulse as an excitation. A similar optimization approach aiming to enhance another attribute, \emph{sparseness}, is experimented numerically on the aforementioned signals as a case study. To summarize, two different objectives each quantifying a certain characteristic are optimized to recover signals carrying valuable information buried in noisy vibration and ultrasonic measurements.

Considering the fact that a research is qualified as successful if it creates more questions than it answers and lets ideas flourish creating scientific value, the presented work aims to achieve this in statistical signal processing. Analytical derivations assisted with experiments form the basis for observations, discussions and further questions to be studied and directed on similar phenomena arising from different sources in nature.

##### Place, publisher, year, edition, pages
Luleå tekniska universitet, 2017
##### Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
##### National Category
Electrical Engineering, Electronic Engineering, Information Engineering
##### Research subject
Signal Processing
##### Identifiers
urn:nbn:se:ltu:diva-64982 (URN)978-91-7583-933-2 (ISBN)978-91-7583-934-9 (ISBN)
##### Public defence
2017-10-18, A109, 10:15 (English)
##### Supervisors
Available from: 2017-08-11 Created: 2017-08-09 Last updated: 2017-11-24Bibliographically approved

#### Open Access in DiVA

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Publisher's full textScopus

#### Authority records BETA

Ovacikli, KubilayCarlson, JohanPääjärvi, Patrik

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Cite
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