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Impulse Response Extraction and Parametric Modelling of Reverberating Ultrasonic Echoes from Thin Layers
Luleå tekniska universitet, Institutionen för system- och rymdteknik. Rubico Vibration Analysis AB.ORCID-id: 0000-0001-6687-7794
Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.ORCID-id: 0000-0002-9992-7791
Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.ORCID-id: 0000-0002-6216-6132
Rubico AB, Luleå.
2015 (engelsk)Inngår i: 2015 IEEE International Ultrasonics Symposium (IUS 2015): Taipei, 21-24 Oct. 2015, Piscataway, NJ: IEEE Communications Society, 2015, artikkel-id 7329331Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Enhacement of material impulse response buried in reverberating ultrasonic echoes from thin layered materials can be exploited in order to be able to detect possible flaws. One of the methods presented in this study is to enhance the impulse response of a material by training an adaptive filter that promotes and appropriate statistical characteristic such as asymmetry. The other approach is to employ a parametric linear model of reverberations that utilizes Maximum Likelihood Estimation on its parameters, to later suppress the reverberations and reveal possible flaws. Both approaches are investigated and shown to succeeed under certain conditions and supported with experiments.

sted, utgiver, år, opplag, sider
Piscataway, NJ: IEEE Communications Society, 2015. artikkel-id 7329331
Serie
Proceedings - IEEE Ultrasonics Symposium, ISSN 1948-5719
Signalbehandling
Identifikatorer
ISI: 000366045700254Scopus ID: 2-s2.0-84962032565Lokal ID: d822993e-94e1-4b7c-8f15-9ebddadf684eISBN: 978-1-4799-8182-3 (tryckt)OAI: oai:DiVA.org:ltu-38946DiVA, id: diva2:1012453
Konferanse
IEEE International Ultrasonics Symposium : 21/10/2015 - 24/10/2015
Validerad; 2016; Nivå 1; 20151011 (migcas)Tilgjengelig fra: 2016-10-03 Laget: 2016-10-03 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Inngår i avhandling
1. Blind Adaptive Extraction of Impulsive Signatures from Sound and Vibration Signals
Åpne denne publikasjonen i ny fane eller vindu >>Blind Adaptive Extraction of Impulsive Signatures from Sound and Vibration Signals
2017 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
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.

sted, utgiver, år, opplag, sider
Luleå tekniska universitet, 2017
Serie
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Signalbehandling
Identifikatorer
urn:nbn:se:ltu:diva-64982 (URN)978-91-7583-933-2 (ISBN)978-91-7583-934-9 (ISBN)
Disputas
2017-10-18, A109, 10:15 (engelsk)
Veileder
Tilgjengelig fra: 2017-08-11 Laget: 2017-08-09 Sist oppdatert: 2017-11-24bibliografisk kontrollert

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