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dc.contributor.advisorPettersson, Klas
dc.contributor.authorKarzhou, Andrei
dc.date.accessioned2023-06-15T12:43:31Z
dc.date.available2023-06-15T12:43:31Z
dc.date.issued2023-07-05
dc.description.abstractThe thesis provides a study of acoustical performance and characterisation of solid-liquid composites. We address both experimental and numerical aspects of fluid-solid interaction problems. In the experimental part, we perform a comparative study of the sound damping properties of perforated plates with viscoelastic inclusions, such as polyurethane and soap emulsified with oil grease lubricant, as well as layered plates with isolated viscoelastic inclusions. One of the computational problems closely related to the experimantal study, is an acoustic fluid-solid interaction problem for plates with a rough surface. We propose an iterative algorithm for the numerical solution of acoustic fluid-solid interaction problems based on a partitioning method. Another fundamental task in acoustics is to model the sound pressure field under harmonic excitation. We apply a machine learning approach and present a feedforward dense neural network for computing the average sound pressure over a frequency range in polygonal cylinders. The sound waves propagation in fluid media is described by a wave equation with corresponding boundary and initial conditions. Given the parameters of the medium, one can determine the acoustic pressure, which is called a direct task. In the last part of the thesis, we solve a coefficient inverse problem: Given the acoustic pressure in some domain, we determine the wave speed function in the time-harmonic acoustic wave equation. For this purpose, the Lagrangian approach for the optimization of the Tikhonov functional is used.en_US
dc.description.doctoraltypeph.d.en_US
dc.description.popularabstractThis thesis studies acoustical properties of solid-liquid composites, i.e. materials with liquid components incorporated into a solid matrix, and related computational problems. We investigate the sound attenuation in perforated plates filled with polyurethane and oil grease lubricant, as well as plates with isolated inclusions. When emitted sound meets an elastic obstacle, an interaction on the interface between the fluid and the solid occur. This interaction problem can be handled by a partitioning method, i.e. the equations in the fluid and solid domains are solved alternately. The frequency response is a measure of the output as a function of input frequency. Machine learning methods can help to predict the frequency response for the average characteristics of a system with complex geometry. In nonhomogenious media sound waves of different frequencies travel with different speed. We can recover the material properties given the observed sound pressure by solving the inverse problem.en_US
dc.identifier.isbn978-82-7823-247-7
dc.identifier.isbn978-82-7823-248-4
dc.identifier.urihttps://hdl.handle.net/10037/29410
dc.language.isoengen_US
dc.publisherUiT Norges arktiske universiteten_US
dc.publisherUiT The Arctic University of Norwayen_US
dc.relation.haspart<p>Paper I: Karzhou, A., Pettersson, I. & Pettersson, K. Insertion loss of macro-perforated plates with viscoelastic filling. (Submitted manuscript). <p>Paper II: Karzhou, A. An iterative FEM-scheme for a fluid-solid acoustic problem. (Submitted manuscript). <p>Paper III: Pettersson, K., Karzhou, A. & Pettersson, I. (2022). A Feedforward Neural Network for Modeling of Average Pressure Frequency Response. <i>Acoustics Australia, 50</i>(2), 185–201. Also available in Munin at <a href=https://hdl.handle.net/10037/27449>https://hdl.handle.net/10037/27449</a>. <p>Paper IV: Karzhou, A., Pettersson, I., Beilina, L. & Pettersson, K. (2023). Numerical validation of optimization approach for solution of coefficient inverse problem in pseudo-frequency domain. (Manuscript). To appear in Asadzadeh, M., Beilina, L. & Takata, S. (Eds.), <i>Gas Dynamics with Applications in Industry and Life Sciences – On Gas Kinetic/Dynamics and Life Science Seminar, March 25—26, 2021 and March 17-–18, 2022. Conference proceedings</i>. Springer, Cham, Switzerland. In press.en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2023 The Author(s)
dc.rights.urihttps://creativecommons.org/licenses/by-nc-sa/4.0en_US
dc.rightsAttribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)en_US
dc.subjectVDP::Mathematics and natural science: 400::Mathematics: 410::Applied mathematics: 413en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Matematikk: 410::Anvendt matematikk: 413en_US
dc.subjectVDP::Mathematics and natural science: 400::Physics: 430::Electromagnetism, acoustics, optics: 434en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Fysikk: 430::Elektromagnetisme, akustikk, optikk: 434en_US
dc.titleAcoustical properties of solid-liquid composites and related computational problemsen_US
dc.typeDoctoral thesisen_US
dc.typeDoktorgradsavhandlingen_US


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