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Blind Adaptive Extraction of Impulsive Signatures from Sound and Vibration Signals
Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems. Rubico AB.ORCID iD: 0000-0001-6687-7794
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
ISBN: 978-91-7583-933-2 (print)ISBN: 978-91-7583-934-9 (electronic)OAI: oai:DiVA.org:ltu-64982DiVA, id: diva2:1130347
##### 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
##### List of papers
1. Uncovering harmonic content via skewness maximization: a Fourier analysis
Open this publication in new window or tab >>Uncovering harmonic content via skewness maximization: a Fourier analysis
2014 (English)In: Proceedings of the 22nd European Signal Processing Conference (EUSIPCO 2014): Lisbon, Portugal, 1-5 Sept. 2014, Piscataway, NJ: IEEE Communications Society, 2014, p. 481-485, article id 6952135Conference paper, Published paper (Refereed)
##### Abstract [en]

Blind adaptation with appropriate objective function results in enhancement of signal of interest. Skewness is chosen as a measure of impulsiveness for blind adaptation to enhance impacting sources arising from defective rolling bearings. Such impacting sources can be modelled with harmonically related sinusoids which leads to discovery of harmonic content with unknown fundamental frequency by skewness maximization. Interfering components that do not possess harmonic relation are simultaneously suppressed with proposed method. An experimental example on rolling bearing fault detection is given to illustrate the ability of skewness maximization in uncovering harmonic content.

##### Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2014
##### Series
Proceedings of the European Signal Processing Conference (EUSIPCO), ISSN 2076-1465
##### National Category
Signal Processing
##### Research subject
Signal Processing
##### Conference
European Signal Processing Conference : 01/09/2014 - 05/09/2014
##### Note
Godkänd; 2014; 20141120 (kubova)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-12-13Bibliographically approved
2. Recovering Periodic Impulsive Signals Through Skewness Maximization
Open this publication in new window or tab >>Recovering Periodic Impulsive Signals Through Skewness Maximization
2016 (English)In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 64, no 6, p. 1586-1596Article in journal (Refereed) Published
##### Abstract [en]

Maximizing the skewness of a measured signal by adaptive filtering to reveal hidden periodic impulses is proposed as a pre-processing method. Periodic impulsive signals are modelled by harmonically related sinusoids to prove that amplitude and phase distortion from a transfer function, effects of sinusoidal interferences and noise can be compensated for by a linear filter. The convergence behaviour of the skewness maximization algorithm is analysed to show that it is possible to recover the original harmonic structure with an unknown fundamental frequency by achieving maximum skewness in the given signal. It is shown that maximizing the skewness always results in a sub-space containing only a single harmonic family. Defect detection in rolling element bearings is presented as an application example and as a comparative study against kurtosis maximization.

##### National Category
Signal Processing
##### Research subject
Signal Processing
##### Identifiers
urn:nbn:se:ltu:diva-8257 (URN)10.1109/TSP.2015.2502549 (DOI)6bc9d02f-2424-4591-a43c-b43de62692d6 (Local ID)6bc9d02f-2424-4591-a43c-b43de62692d6 (Archive number)6bc9d02f-2424-4591-a43c-b43de62692d6 (OAI)
##### Note

Validerad; 2016; Nivå 2; 20151101 (johanc)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
3. Impulse Response Extraction and Parametric Modelling of Reverberating Ultrasonic Echoes from Thin Layers
Open this publication in new window or tab >>Impulse Response Extraction and Parametric Modelling of Reverberating Ultrasonic Echoes from Thin Layers
2015 (English)In: 2015 IEEE International Ultrasonics Symposium (IUS 2015): Taipei, 21-24 Oct. 2015, Piscataway, NJ: IEEE Communications Society, 2015, article id 7329331Conference paper, Published paper (Refereed)
##### 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.

##### Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2015
##### Series
Proceedings - IEEE Ultrasonics Symposium, ISSN 1948-5719
##### National Category
Signal Processing
##### Research subject
Signal Processing
##### Conference
IEEE International Ultrasonics Symposium : 21/10/2015 - 24/10/2015
##### Note
Validerad; 2016; Nivå 1; 20151011 (migcas)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-12-13Bibliographically approved
4. Blind pulse compression through skewness maximization on overlapping echoes from thin layers
Open this publication in new window or tab >>Blind pulse compression through skewness maximization on overlapping echoes from thin layers
2016 (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
##### Series
Proceedings - IEEE Ultrasonics Symposium, ISSN 1948-5719
##### Keyword
Dictionary Learning, Acoustic Emission
##### National Category
Signal Processing
##### Research subject
Signal Processing
##### Identifiers
urn:nbn:se:ltu:diva-61039 (URN)10.1109/ULTSYM.2016.7728571 (DOI)000387497400198 ()2-s2.0-84996489201 (Scopus ID)67766b7e-31af-44f5-b818-97f7fc13e9fc (Local ID)978-1-4673-9897-8 (ISBN)978-1-4673-9898-5 (ISBN)67766b7e-31af-44f5-b818-97f7fc13e9fc (Archive number)67766b7e-31af-44f5-b818-97f7fc13e9fc (OAI)
##### 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
5. Blind Enhancement of Harmonically Related Signals by Maximizing Skewness
Open this publication in new window or tab >>Blind Enhancement of Harmonically Related Signals by Maximizing Skewness
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
##### Abstract [en]

Rolling element bearings are used in rotating machinery in various industry branches. Their health status must be monitored continuously in order to establish proper operational conditions in a production process. Numerous approaches, which can be investigated under the subject of Condition Based Maintenance", have been studied within mechanical engineering and signal processing to be able to detect and classify possible faults on rolling bearings.Periodic impulsive signals can emerge from defected bearings within rotating machinery. As the signal is distorted by an unknown transfer function, noise and severe interference, the challenge becomes to reduce these effects as much as possible to extract valuable and reliable information about the rolling bearings' health status. Without any observation of the source signal, a scale-invariant higher order moment, skewness, can be used as a tool to characterize statistical properties to enhance the desired signal. It is the impulsiveness, thus asymmetry of the signal that will be promoted. To assess the performance of skewness, a signal model that consists of harmonically related sinusoids representing an impulsive source is built. Depending on such a model, surface characteristics of skewness are investigated. In relation to harmonic content, the ability of skewness in discovering such harmonic relation is studied. It has been observed that the optimization process converges to a setting where all harmonics are preserved, while any component that does not possess such a harmonic relation is suppressed. In the case of multiple mutually inharmonic source signals with harmonic support, it is shown that skewness maximization results in a setting where only the harmonic set with highest skewness remains. Finally, experimental examples are provided to support theoretical findings.

##### Place, publisher, year, edition, pages
Luleå tekniska universitet, 2014
##### Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
##### National Category
Signal Processing
##### Research subject
Signal Processing
##### Identifiers
urn:nbn:se:ltu:diva-26461 (URN)e5906010-90eb-433e-a39f-7f3d5e682f7d (Local ID)978-91-7439-917-2 (ISBN)978-91-7439-918-9 (ISBN)e5906010-90eb-433e-a39f-7f3d5e682f7d (Archive number)e5906010-90eb-433e-a39f-7f3d5e682f7d (OAI)
##### Note
Godkänd; 2014; 20140214 (kubova); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Aziz Kubilay Ovacikli Ämne: Signalbehandling/Signal Processing Uppsats: Blind Enhancement of Harmonically Related Signals by Maximizing Skewness Examinator: Professor Johan Carlson, Institutionen för system- och rymdteknik, Luleå tekniska universitet Diskutant: Tekn. Dr. Magnus Sandell, Toshiba Research Labs, Bristol, UK Tid: Onsdag den 4 juni 2014 kl 10.15 Plats: A1545, Luleå tekniska universitetAvailable from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-12-13Bibliographically approved
6. Skewness as an objective function for vibration analysis of rolling element bearings
Open this publication in new window or tab >>Skewness as an objective function for vibration analysis of rolling element bearings
2014 (English)In: 2013 8th International Symposium on Image and Signal Processing and Analysis (ISPA 2013: Trieste, Italy, 4-6 Sept. 2013, Piscataway, NJ: IEEE Communications Society, 2014, p. 462-466Conference paper, Published paper (Refereed)
##### Abstract [en]

The scale invariant third order moment, skewness, is analysed as an objective function to an adaptive gradient ascent algorithm. The purpose is to achieve a spectrum at the filter output that can enable identification of possible bearing defect signatures which are impulsive and periodic. Harmonically related sinusoids are used to represent such signatures and to build a signal model allowing characterization of the objective surface of skewness, providing insight to its convergent behaviour. The results are supported with an experiment from an industry setting. Robustness of the proposed algorithm is demonstrated by examining the frequency spectrum resulting from the signal model.

##### Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2014
##### National Category
Signal Processing
##### Research subject
Signal Processing
##### Identifiers
urn:nbn:se:ltu:diva-31882 (URN)631fe16d-ee34-4da2-aa13-b4b4387e315d (Local ID)9781479931255 (ISBN)631fe16d-ee34-4da2-aa13-b4b4387e315d (Archive number)631fe16d-ee34-4da2-aa13-b4b4387e315d (OAI)
##### Conference
International Symposium on Image and Signal Processing and Analysis : 04/09/2013 - 06/09/2013
##### Note
Godkänd; 2014; 20140113 (kubova)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-12-13Bibliographically approved
7. Material Impulse Response Estimation from Overlapping Ultrasound Echoes Using a Compressed Sensing Technique
Open this publication in new window or tab >>Material Impulse Response Estimation from Overlapping Ultrasound Echoes Using a Compressed Sensing Technique
2017 (English)In: IEEE International Ultrasonics Symposium, IUS, Washington D.C.: IEEE Computer Society, 2017, article id 8092248Conference paper, Published paper (Refereed)
##### Abstract [en]

In ultrasound examination of thin multi-layered materials, the received signal is, in both through-transmission and pulse-echo configurations, a superposition of multiple reflections from inside the sample. If the layer thicknesses are small compared to the duration of the emitted ultrasound pulse, the received signal will be a sum of overlapping ultrasound pulses. In such scenarios, estimation of the layer thicknesses is challenging. Previous work has adopted model-based decomposition of the overlapping echoes, or various pulse compression or deconvolution schemes, in order to better reveal the arrival times of each individual echo.

##### Place, publisher, year, edition, pages
Washington D.C.: IEEE Computer Society, 2017
##### National Category
Signal Processing
##### Research subject
Signal Processing
##### Identifiers
urn:nbn:se:ltu:diva-64966 (URN)10.1109/ULTSYM.2017.8092248 (DOI)2-s2.0-85039420470 (Scopus ID)9781538633830 (ISBN)
##### Conference
2017 IEEE International Ultrasonics Symposium (IUS), Washington, DC, 6-9 Sept. 2017
Available from: 2017-08-07 Created: 2017-08-07 Last updated: 2018-01-11Bibliographically approved

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Cite
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