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Doctoral theses

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Identifier

000402756

Title

Velocity estimation using cross-correlations of ambient noise recordings

Alternative Title

Θεωρητική και αριθμητική μελέτη του προβλήματος ανάκτησης μεταβολών της σχετικής ταχύτητας διάδοσης στο υπέδαφος με χρήση του θορύβου περιβάλλοντος

Author

Δασκαλάκης, Εμμανουήλ

Thesis advisor

Τσόγκα, Χρυσούλα

Reviewer

Ευαγγελίδης, Χρήστος
Garnier, Josselin
Χαρμανδάρης, Βαγγέλης
Μακράκης, Γεώργιος
Παπανικολάου, Γεώργιος
Πλεξουσάκης, Μιχάλης

Abstract

The main subject of this thesis is the use of cross-correlations of noise recordings for esti¬mating the velocity and the velocity variations in a medium. The cross-correlation function of the noise recordings at two sensor locations is related to the Green's function between these two sensors. This relation largely depends on the spatial distribution and the frequency content of the noise sources. In part I we investigate how seasonal variations in the spatial distribution and the fre¬quency content of the noise affect the measurement of the velocity variation in a medium and we suggest a possible treatment to that problem which works under some assumptions on the seasonal variations. In part II we study the problem of velocity tomography using noise recordings. In par¬ticular we study the Eikonal Tomography and more specifically the impact that different interpolation schemes have on the estimation obtained by Eikonal tomography. We also introduce the Kriging interpolation method as an alternative approach to the classical de¬terministic methods. In part III we use noise recordings (Structural Vibrations) from sensors positioned at a historic masonry bell-tower in Perugia for Structural Health Monitoring (SHM). We intro¬duce a new method to detect changes in the natural frequencies of the structure which are associated with structural damage.

Language

English

Subject

Seismic noise

Σεισμικός θόρυβος

Issue date

2016

Collection

School/Department--School of Sciences and Engineering--Department of Applied Mathematics--Doctoral theses

Type of Work--Doctoral theses

Permanent Link

https://elocus.lib.uoc.gr//dlib/f/6/8/metadata-dlib-1473414354-659699-32051.tkl