Dissertations / Theses on the topic 'Surface waves'
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Jamali, Mirmosadegh. "Surface wave interaction with oblique internal waves." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0024/NQ38904.pdf.
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McHugh, Christine A. "Control of surface waves." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385451.
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Haskell, Reichl B. "A Surface Acoustic Wave Mercury Vapor Sensor." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/HaskellRB2003.pdf.
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Gross, Johann. "Evaluation of near surface material degradation in concrete using nonlinear Rayleigh surface waves." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45810.
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Comparative studies of nondestructive evaluation methods have shown that nonlinear ultrasonic techniques are more sensitive than conventional linear methods to changes in material microstructure and the associated small-scale damage. Many of the material degradation processes such as carbonation in concrete, corrosion in metals, etc., begin at the surface. In such cases, ultrasonic Rayleigh surface waves are especially appropriate for detection and characterization of damage since their energy is concentrated in the top layer of the test object. For the civil engineering infrastructure, only a limited number of field applicable nonlinear ultrasonic techniques have been introduced. In this paper a nonlinear ultrasonic measurement technique based
on the use of Rayleigh waves is developed and used to characterize carbonation in concrete samples. Wedge transducer is used for the generation and an accelerometer for detection of the fundamental and modulated ultrasonic signal components. The measurements are made by varying the input voltage and along the propagation distance. The slope of the normalized modulated amplitudes is taken as the respective nonlinearity parameter. Concrete samples with two different levels of damage are
examined, and the difference of the two fundamental frequencies is used to quantify
damage state.
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KHOSRO, ANJOM FARBOD. "S-wave and P-wave velocity model estimation from surface waves." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2912984.
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Fedorov, Alexey V. "Nonlinear effects in surface and internal waves /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9737309.
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Bright, Victor M. "Shear horizontal surface acoustic waves." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/14831.
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Gong, Chen. "Surface waves in elastic material." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227640.
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A finite volume method based solver for Rayleigh waves in two dimensional elastic materials is constructed by using the Conservation Laws Package (Clawpack). The Lax-Wendroff scheme is implemented and only first-order accuracy is achieved for the Rayleigh wave problems by the default elastic wave solver in Clawpack. A Lamb's problem is solved by Clawpack and some instabilities occur in the cases of almost incompressible materials. The Rayleigh wave problem in complex geometries is transformed by a smooth mapping function and solved by using a fourth-order summation-by-parts (SBP) operators with a simultaneous approximation term (SAT) method. The stability is proved by the energy method in the continuous and discrete form. The numerical experiment shows that the curved boundary has influences on the magnitude and phase of the Rayleigh waves.
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Bourquin, Yannyk Parulian Julian. "Shaping surface waves for diagnostics." Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/4167/.
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Infectious diseases continue to kill millions of people every year and are a significant burden on the socio-economic development of developing countries. After many years of international policy aimed at containing diseases, it has recently become an explicit aim to move towards elimination of infectious diseases. However, if this is to occur, it will be necessary to have highly eficacious diagnostic tools to ensure infected individuals are identified and treated. However, the diagnosis of infectious diseases in the developed and developing world requires the full integration of complex assays in easy-to-use platforms with robust analytical performances at low cost. Many relevant bioanalytical technologies have been developed for use in laboratories and clinics, including the current gold standard for the diagnosis of tuberculosis and malaria. The miniaturization and integration of complex functions into lab-on-a-chip (LOC)technologies using microfluidics have only had limited success in translating diagnosis assays out of a centralized laboratory to point-of-care (POC) settings, because they still remain constrained due to chip interconnection and they are either not likely to go out of research laboratories or are not appropriate for low resource settings. In this thesis, a new microfluidic platform was developed that reduced the dependency of the diagnostic procedure on large laboratory instruments providing simplicity of use, enabling the patient sample to be processed and diagnosed on a low cost, disposable biochip. Surface acoustic wave (SAW) devices, which are commonly used in mobile phone technologies, were adapted to provide controlled microfluidic functions by shaping the SAW using particular designs of electrodes and phononic structures. The control of lateral positioning of the SAW was demonstrated using a slanted finger interdigitated transducer (IDT) in a frequency tuneable manner allowing microfluidic functions such as mixing, moving and merging, sequentially performed using a single IDT both on the substrate and on a disposable chip. Alternatively, phononic bandgaps were designed to break the symmetry of the SAW in a tuneable manner and gradient index phononic crystals (GRIN-PC) lenses were designed to focus the SAW and successfully increased the amplitude of the wave by a factor 3 while the focal position could be tuned with the frequency. The potential of these techniques was demonstrated by controlling the amplitude and direction of water jet towers by the use of a phononic horn structure that allowed the enhancement of energy at defined positions and by propelling and directing a macrometer scale object in water using a slanted IDT. As proof of concepts of diagnostic devices for the developing world, an immunoassay for tuberculosis using only mobile phone technologies (SAW, light-emitting diode(LED) and complementary metaloxidesemiconductor (CMOS) camera) was demonstrated with a limit of detection of 1 pM, which is the limit required in an interferon-release assay. This limit of detection was only achievable because of the ability of SAW to increase the mixing and to reduce the non-specific binding. Furthermore, a method to enrich malaria infected cells, based on SAW and isopycnic gradient, was also demonstrated and showed an enrichment up to 100x in the equivalent of a fingerprick of blood in 3 seconds. This technique will allow to reduce the limit of detection of the current gold standard. This platform not only opens a clear road toward POC diagnostics due to its size, cost, versatility and ease in integration, but has also the potential to provide useful tools in laboratory settings for large scale, high throughput technologies.
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Kovalevich, Tatiana. "Tunable Bloch surface waves devices." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD022/document.
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Cette thèse est consacrée au développement de dispositifs accordables sur la base de cristaux photoniques unidimensionnels qui peuvent supporter des ondes de surface de Bloch (BSW). Tout d'abord, nous explorons les possibilités de contrôler la direction de propagation des BSW par le biais de la polarisation de la lumière incidente. Dans ce cas, nous gravons sur le dessus du cristal photonique 1D des structures passives de type réseau, qui permettent à la fois de coupler la lumière incidente aux BSWs et de se comporter comme une lame séparatrice ultracompacte contrôlée par la polarisation lumineuse. Nous avons testé ce type de coupleur sur des cristaux photoniques 1D fonctionnant dans l’air et dans l’eau. Ensuite, nous démontrons l'accordabilité des BSWs en ajoutant une fine couche active dans la structure photonique multicouche. Il s’agit d’un film mince de niobate de lithium monocristallin qui permet d’introduire des propriétés anisotropes dans le cristal photonique 1D. Différentes façons de fabriquer des cristaux photoniques 1D contenant du niobate de lithium monocristallin ont été développées dans le cadre de ce travail. Ces travaux nous ont permis d’explorer le concept de contrôle électro-optique des BSWsThis thesis is devoted to develop tunable devices on the base of one-dimensional photonic crystals (1DPhC) which can sustain Bloch surface waves (BSWs).First, we explore the possibilities to control the BSW propagation direction with polarization of incident light. In this case we manufacture additional passive structures such as gratings on the top of the 1DPhC, which are working both as a BSW launcher and polarization–controlled “wave-splitters”. We test this type of launcher in air and in water as an external medium. Then, we demonstrate the tunability of the BSW by adding an active layers into the multilayer stack. Here a crystalline X-cut thin film lithium niobate (TFLN) is used to introduce anisotropic properties to the whole 1DPhC. Different ways to manufacture 1D PhCs with LiNbO3 on the top would be described. Finally, we explore the concept of the electro-optically tuned BSW
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Marquardt, Matthew William Stern Frederick Longo Joseph. "Effects of waves and the free surface on a surface-piercing flat-plate turbulent boundary layer and wake." [Iowa City, Iowa] : University of Iowa, 2009. http://ir.uiowa.edu/etd/404.
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Stewart, William F. "Buried object detection using surface waves /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA305744.
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Thesis (M.S. in Engineering Acoustics) Naval Postgraduate School, September 1995."September 1995." Thesis advisor(s): Anthony A. Atchley. Includes bibliographical references. Also available online.
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Rostad, Torbjørn. "Optical Detection of Surface Acoustic Waves." Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9487.
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This project was worked on during the autumn 2005 at the Norwegian University of Science and Technology, Department of Electronics and Telecommunications. The assignment was to write a new LabVIEW programme that is to run the measurement procedure of a laser probe setup. The setup is used in characterization of surface acoustic waves(SAW). A programme was written that contained the necessary functionality and proved to operate satisfactorily. Several measurements were made on a SAW transducer, accurately picturing the wave. Fourier analysis were performed on the collected data in order to separate the propagation directions. An absolute amplitude measurement was made on a heterodyne interferometer, and the result was compared to a similar scan made using the laser probe. The work shows that the setup is ready for calibration against the heterodyne interferometer, in order to enable the laser probe to measure absolute amplitude by itself.
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Hesse, Daniel. "Rail inspection using ultrasonic surface waves." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444161.
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Mutti, Paolo. "Surface acoustic waves for semiconductor characterization." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357598.
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Harvey, Alan Paul. "Nonlinear surface acoustic waves and applications." Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255827.
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Chen, Wenchen. "Metamaterials, Surface Waves, and Their Applications." Thesis, Boston College, 2014. http://hdl.handle.net/2345/bc-ir:103748.
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Thesis advisor: Willie J. PadillaThe field of metamaterials (MMs) has garnered a great deal of attention ever since the experimental demonstration of negative refractive indexes. Such an exotic response stemmed from the engineering capability of MMs, as they can obtain almost any optical responses at any given frequency by carefully structuring the geometries. There are countless examples where MMs have posed promising results in tailoring free space radiation. However, their usage beyond this common platform is far less explored. For examples, surface electromagnetic waves, which offer great potentials for future device applications, could be an intriguing place for the further development of metamateirals. In this dissertation, we study various MM configurations where the interplay between surface waves and metamaterials has a significant impact on the device performance. Firstly, Chapter 1 introduces some fundamental concepts of metamaterials and surface electromagnetic waves, and outline the fabrication, experiments, and characterization details. In Chapter 2, we investigate whether the effective optical parameters of MMs have the exact physical meaning as those of natural substances. Two types of MM resonators are studied, and we found the thickness of the host matrix plays a crucial role in such a homogenization process. Next, we present a computational and experimental study of MMs in conjunction with a novel gigahertz/terahertz transmission line, in Chapter 3. By optimizing the coupling between the MMs and the signal, information can be encoded. Chapter 4 presents a study of designing an extremely subwavelength magnetic MM. By maximizing the effective inductance and capacitance of the structure, the final geometry obtains a strong magnetic resonance with the size of merely λₒ/2000, where λₒ is the resonant wavelength. A novel time-domain spectroscopic method is also proposed to determine the frequency-dependent permeability of the samples. In Chapter 5, we characterize two hidden channels of MM perfect absorbers : scattering and generation of surface electromagnetic waves. In particular, we unveil lossy surface waves are generated during the process resulting in an enhancement of angular absorbance. The study provides a new insight to the working principle of MMAs. In Chapter 6, we investigate complementary MM structures that exhibit strong extraordinary optical transmission with higher transmission efficiency. We discover the origin of the fundamental mode is irrelevant to the Bloch modes. Lastly, we summarize all achievements and give an outlook in Chapter 7
Thesis (PhD) — Boston College, 2014
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics
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Thomas, Alexandra Elizabeth. "The interaction of an internal solitary wave with surface gravity waves." Thesis, University of Edinburgh, 2002. http://hdl.handle.net/1842/13106.
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Solitary waves are nonlinear, non-oscillatory disturbances of permanent form. Recent advances in synthetic aperture radar imaging and analysis techniques have confirmed in situ observations and measurements that the passage of oceanic internal waves, and in particular internal solitary waves, is associated with modulations in sea surface roughness. It has not only revealed the ubiquity of this phenomenon but also highlighted the global existence of large amplitude, tidally induced, internal solitary waves. It appears, however, that little laboratory-based research has been carried out in this field. This work, therefore, focusses on the study of surface wavetrain modulations resulting from the passage of a single internal solitary wave. Digital Particle Image Velocimetry (DPIV) and Planar Laser Induced Fluorescence (PLIF) were employed to provide two-dimensional instantaneous velocity and density information respectively. Previous studies in this field have been performed with intrusive probe techniques, disturbing the fluid flow during measurement. Preliminary DPIV and PLIF experiments were performed on single internal solitary waves in a two-layer brine - fresh water stratification. To the author’s knowledge, the application of PLIF to the study of these waves had not been done previously. Results from the DPIV measurements concurred with previous research and highlighted the constraints of the DPIV system. The results were also compared to a recently developed and validated fully nonlinear numerical method. From the interaction investigations, both wavelength and amplitude modulations of the surface waves as a function of solitary wave phase were observed. In some cases, the shape of the internal wave was also affected. Velocity profiles were compared to the linear superposition of surface wave linear theory and the fully nonlinear numerical method. In addition, the PLIF analysis showed that, for the wave and stratification parameters investigated, there was no evidence for the compression and expansion of the density interface during the interaction.
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Chan, Tak-yee Andy. "The interaction of laminar far wake with a free surface /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1856544X.
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Terrill, Eric J. "Acoustic measurements of air entrainment by breaking waves /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9907829.
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Schlottmann, Robert Brian. "A path integral formulation of elastic wave propagation /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004372.
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Hebeler, Gregory L. "Site characterization in Shelby County, Tennessee using advanced surface wave methods." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/20996.
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Wang, Bingnan. "Wave propagation in photonic crystals and metamaterials surface waves, nonlinearity and chirality /." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3389159.
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Ohl, Clifford Owen Groome. "Free surface disturbances and nonlinear runup around offshore structures." Thesis, University of Oxford, 2000. http://ora.ox.ac.uk/objects/uuid:320ff8da-c225-40da-a7dd-d6cf55c97b51.
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Diffraction of regular waves, focused wave groups, and random seas by arrays of vertical bottom mounted circular cylinders is investigated using theoretical, computational, and experimental methods. Free surface elevation η is the defining variable used to test the potential theory developed. In addition, the nonlinearity of focused wave groups is investigated through the Creamer nonlinear transform and analysis of numerical wave tank data. Linear focused wave group theory is reviewed as a method for predicting the probable shape of extreme events from random wave spectra. The Creamer nonlinear transform, a realistic model for steep waves on deep water, is applied in integral form to simulate nonlinear focused wave groups. In addition, the transform is used to facilitate analysis of nonlinear wave-wave interactions within focused wave groups from a uni-directional numerical wave tank developed at Imperial College London. Experiments in an offshore wave basin at HR Wallingford are designed to measure free surface elevation at multiple locations in the vicinity of a multicolumn structure subjected to regular and irregular waves for a range of frequencies and steepness. Results from regular wave data analysis for first order amplitudes are compared to analytical linear diffraction theory, which is shown to be accurate for predicting incident waves of low steepness. However, second and third order responses are also computed, and the effects in the vicinity of a second order near trapping frequency are compared to semi-analytical second order diffraction theory. Analytical linear diffraction theory is extended for application to focused wave groups and random seas. Experimental irregular wave data are analysed for comparison with this theory. Linear diffraction theory for random seas is shown to give an excellent prediction of incident wave spectral diffraction, while linear diffraction theory for focused wave groups works well for linearised extreme events.
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盧慧 and Hui Loo. "Effect of surface waves on pollutant dispersion." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31224866.
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Ash, Benjamin James. "Locally resonant metamaterial for surface acoustic waves." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/34380.
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The control of surface acoustic waves (SAWs) using arrays of annular holes was investigated both experimentally and through numerical modelling. Periodic elastic composites, phononic crystals (PnCs), were designed using these annular holes as constituent elements. Local resonances associated with the annular hole structure were found to induce phonon bandgaps of a highly frequency tailorable nature, at frequencies where radiation of acoustic energy into the bulk of the substrate medium is avoided. These bandgaps are numerically demonstrated to exhibit order-of-magnitude improved extinction ratios for finite numbers of PnC elements, relative to the commonly used cylindrical pillar architecture. Devices fabricated on commercially available lithium niobate SAW delay lines verify the predicted behaviour. Through laser knife-edge detector vibrometry, a bandgap attenuation of 24.5 dB at 97 MHz was measured, in excellent agreement with finite element method (FEM) simulations. The first reported experimental evidence of subwavelength confinement of propagating SAWs was realised using the same annular hole PnC concept. Defect holes of perturbed resonant frequencies are included within the PnC to define waveguides and cavities. Confinement within these defects was demonstrated to occur at subwavelength frequencies which was experimentally observed in fabricated cavities using standard SAW transducers, as measured by laser Doppler vibrometry. The success of this result was attributed to the impedance matching of hybridised modes to Rayleigh SAWs in un-patterned substrates at the defect resonance. The work here has the potential to transform the field by providing a method to enhance SAW interactions, which is a route towards the realisation of many lab-on-chip applications. Finally, the use of annular hole arrays as negative refraction metamaterials was investigated. The symmetry was broken of the unit cells by alternating either the locally resonant frequencies or the distance separating the constituent elements. Both methods, called the bi-dispersive and bi-periodic methods, were numerically demonstrated to exhibit negative group velocity bands within the first Brillouin zone. Preliminary experimental results show that the design has the potential to be used in superlensing, where a SAW spot was imaged over a subwavelength flat lens. Future research looks to demonstrate that this result can be attributed to negative refraction.
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Costa, George 1976. "Investigation of surface waves on hydrodynamic lubrication." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/89263.
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Hancock, Matthew James 1975. "Generation of sand bars under surface waves." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/27870.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 277-282).
(cont.) Experiments were performed in a large wave flume to validate the theory and to study additional aspects of sand bar evolution. The wave envelope and bar profile were recorded for low and high beach reflection, monochromatic and polychromatic waves, and several sediment grain sizes. In particular, sediment sorting was demonstrated under standing waves when the seabed consisted of initially well mixed sand of two grain sizes.
A quantitative theory is described for the evolution of sand bars under monochromatic surface water waves. By assuming the slopes of the waves and seabed are comparably gentle, an approximate evolution equation is found for the seabed elevation. The boundary layer structure is calculated by assuming a depth-linear or depth-independent time-invariant eddy viscosity. An empirical formula by Sleath (1978) is used to predict the bedload transport. A convective diffusion equation governs the suspended sediment transport (which includes the effects of wave-advection), and empirical formulae by Lee et al. (2004) and Wikramanayake & Madsen (1994) specify the time-varying concentration at the seabed. Effects of mean beach slope and narrow banded waves are also considered. The sand bar elevation is found to evolve according to a forced-diffusion equation, where the diffusivity is the gravitational effect on bedload transport on a slope and the forcing is due to both bedload and suspended load transport mechanisms. The time scale of sand bar evolution is over four orders of magnitude longer than the wave period: days in the lab and weeks in the field. In addition to the effects of bedload considered before by Yu & Mei (2000), it is found that suspended load provides a new forcing mechanism affecting sand bar geometry when the seabed is composed of fine sediments. When wave reflection is significant, bars and waves interact through the Bragg scattering mechanism. Under strong reflection, large regions exist where there is no change to the seabed. For weaker reflection, an inviscid return flow is present that places an additional stress on the bed. As shown by Yu & Mei (2000), any finite beach reflection is sufficient to generate and maintain sand bars.
by Matthew James Hancock.
Ph.D.
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Engel, Mark 1962. "Weakly nonlinear surface waves in a ferrofluid." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13515.
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Bedard, Robert J. A. "Laboratory scale experiments with water surface waves." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:7242.
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The thesis presents the development, implementation and results of two series of experiments, at large and small scale, for the study of surface gravity waves. A number of measurement techniques are developed and implemented to capture space and time evolution of waves on a water surface in gravity, gravity-capillary and capillary ranges with the purpose to study the statistics of wave turbulence in terms of frequency and wave number spectra. The first series of experiments was conducted in a large wave tank of size 12 m x 6 m x 1.6 m filled with water to a depth of 0.9 m. A wave maker comprised of eight panels is controlled by a computer to generate waves at typically two frequencies; these waves are directed at different angles. Surface elevation of the resulting turbulent wave field is measured via capacitance wire probes and a fluorescent laser technique that is capable of capturing wave profiles at sufficient frame rate to access both wavenumber and frequency statistics. Following the processing of these data a comprehensive set of results describe characteristics of the life cycle of the experiment including the rise of the wave field to its statistically stationary state and the decay of the regime after energy pumped into the system from the wave maker has ceased. The first series of experiments was conducted in a large wave tank of size 12 m x 6 m x 1.6 m filled with water to a depth of 0.9 m. A wave maker comprised of eight panels is controlled by a computer to generate waves at typically two frequencies; these waves are directed at different angles. Surface elevation of the resulting turbulent wave field is measured via capacitance wire probes and a fluorescent laser technique that is capable of capturing wave profiles at sufficient frame rate to access both wavenumber and frequency statistics. Following the processing of these data a comprehensive set of results describe characteristics of the life cycle of the experiment including the rise of the wave field to its statistically stationary state and the decay of the regime after energy pumped into the system from the wave maker has ceased. Across both series of experiments the implementation of data acquisition techniques forms a significant contribution to the work undertaken and a comprehensive set of tools for measurement and analysis of data from surface waves is developed.
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Brock, Elizabeth Martine Gerber. "The lateral confinement of microwave surface waves." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/15097.
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Surface waves and their applications have been extensively studied by the photonics and radio engineering communities throughout the whole of the twentieth century. This thesis details briefly the history of both approaches and highlights their signi cance with regard to the subject of this thesis; laterally confining a surface wave in the microwave regime. Detailed within are the experimental, analytical and numerical methods used to ascertain what, if any, effect a change in the dimension of a guiding structure has on the dispersion of a mode supported by a metamaterial. The method of experimentally determining the dispersion of a microwave surface wave is discussed. The insensitivity of a mode supported on a one-dimensional corrugated array to the lateral width of the supporting array, even when the width is much less than the wavelength of radiation incident upon it, is investigated. Spatial dependent reduction of group velocity associated with a microwave surface wave is also detailed. Local electric-field and phase measurements are used to probe this condition. In particular, the measurement of phase associated with the supported microwave surface wave is shown to indicate the trapping location of a surface wave more accurately when compared to local electric-field measurement. The channelling of surface waves via the addition of dielectric overlayers to a metamaterial surface is investigated. By progressively narrowing the width of the channel, the interaction of the electric fields associated with the mode supported in the channel with the bordering dielectric overlayer increases. This investigation leads to a discussion of the electric field overlap between two regions of differing surface impedance.
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Damani, Shishir. "Excitation of Acoustic Surface Waves by Turbulence." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/104742.
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Acoustic metamaterials have been shown to support acoustic surface waves when excited by a broadband signal in a quiescent environment and these waves could be manipulated by varying the geometry of the structure making up the metamaterial. The study presented here demonstrates the generation of trapped acoustic surface waves when excited by a turbulent flow source. The metamaterial and flow were interfaced using a Kevlar covered single cavity whose Kevlar side faced the flow to ensure no significant disturbance to the flow and the other side was open to a quiescent (stationary) environment housing the metamaterial. Acoustic measurements were performed very close to the surface of the metamaterial in the Anechoic Wall Jet Facility at Virginia Tech using two probe-tip microphones and correlation analysis yielded the structure of the surface waves. Two different metamaterials; slotted array and meander array were tested and characterized by their dispersion relations, temporal correlations, and spatial-temporal structure. The measurements proved the existence of surface waves with propagating speeds of a tenth of the speed of sound, when excited by a turbulent boundary layer flow. These waves were much weaker than the overlying flow exciting them but showcased excellent attenuation properties away from the source of excitation. Measurements along the length of the unit-cell geometry of the metamaterial demonstrated high coherence over a range of frequencies limited by the dimension of the cell. This was a surprising behavior provided the cavity was excited by a fully developed turbulent flow over a flat plate and indicated to an area averaging phenomenon.
A wall normal two-dimensional particle image velocimetry (2D-PIV) measurement was performed over the Kevlar covered cavity and a smooth surface to study the effects of the cavity on the flow. The field of view was the same for both cases which made direct flow comparison possible. Flow characteristics such as the boundary layer profiles, Reynolds stress profiles and fluctuating velocity spectrum were studied over the cavity and at downstream locations to quantify the differences in the flows. The boundary layer profiles collapsed in the inner region of the boundary layer but there were small differences in the outer region. The Reynolds stress profiles were also very similar with differences within the uncertainties of processing the images and it reflected similar average behavior of the flow over a smooth wall and a Kevlar covered cavity. The fluctuating velocity spectrum studied over the cavity location showed some differences at low frequencies for all wall normal locations while at higher frequencies the differences were within ±3 dB. These measurements showcased the underlying physics behind the interaction of acoustic metamaterials and turbulent boundary layer flows creating possibilities of using these devices for flow control although further analysis/optimization is needed to fully understand the capabilities of these systems. The demonstration of no significant effect on flow by the Kevlar covered cavity stimulated development of sensors which can average over a region of the wall pressure spectrum.M.S.
In the field of physics, acoustic metamaterials have gained popularity due to their ability to exhibit certain properties such as sound manipulation which cannot be seen in regular materials. These materials have a key feature which is the periodic arrangement of geometric elements in any dimension. These materials can support a phenomenon termed as acoustic surface waves which are essentially pressure disturbances in the medium which behave differently than some known phenomenon such as sound waves when excited by a broadband pressure signal in a stationary medium. Also, it has been shown that these materials can change the nature of the acoustic surface waves if their geometry is changed. Here a successful attempt has been made to link two different fields in physics: acoustic metamaterials (acoustics) and turbulent flows (fluid dynamics). The study here uses turbulent boundary layer flows to excite these metamaterials to show the existence of acoustic surface waves. This is done by creating an interface between the flow and the metamaterial using a Kevlar covered through cavity which is essentially a through hole connecting to different sides: flow side and the stationary air/quiescent side. This cavity acted as the source of excitation for the metamaterial. The Kevlar covering ensures that the flow does not get disturbed due to the cavity which was also proved in this study using a visualization technique: Particle Image Velocity (PIV). Two microphones were used to study the pressure field very close to two metamaterials; one was referred to as the slotted array comprised of slot cavities arranged in one dimension (along the direction of the flow), while the other was termed as the meander array and it comprised of a meandering channel. The pressure field was well characterized for both the acoustic metamaterials and it was proved that these metamaterials could support acoustic surface waves even when excited by a turbulent flow. The idea here was to fundamentally understand the interaction of acoustic metamaterials and turbulent flows, possibly finding use in applications such as trailing edge noise reduction. The use of these metamaterials in direct applications needs further investigation. A finding from the pressure field study showed that the pressure measured along the length of the Kevlar covered cavity was uniform. The flow visualization study looked at the turbulent flow on a smooth wall and over a Kevlar covered cavity. This was done by injecting tiny particles in air and shooting a laser sheet over these to illuminate the flow. Images were recorded using a high-speed camera to track the movement of these particles. It was found that the flow was unaffected with or without the presence of a Kevlar covered cavity. This result coupled with the pressure field uniformity could have some wide applications in the field of pressure sensing.
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Janning, Dan. "Surface waves in arrays of finite extent." Connect to resource, 2000. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1209495149.
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Kumon, Ronald Edward. "Nonlinear surface acoustic waves in cubic crystals /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Loo, Hui. "Effect of surface waves on pollutant dispersion." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23273185.
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Miles, Alan J. "Magnetohydrodynamic surface waves in the solar atmosphere." Thesis, University of St Andrews, 1991. http://hdl.handle.net/10023/14225.
Full textAbstract:
In this thesis the nature of magnetoacoustic surface waves at a single magnetic interface is examined for the case of parallel propagation. Above the interface is an isothermal medium permeated by a horizontal magnetic field. The lower region is a field-free medium of different density to the magnetic atmosphere. We consider both the incompressible and compressible situations and the effect of including gravity. In each case a transcendental dispersion relation is solved numerically for a range of parameters and the resulting dispersion curves plotted. In the first chapter we provide a general introduction to the work, reviewing previous work in this area and considering applications of surface waves. In the second chapter we consider the existence of surface waves for the case when the media are incompressible either side of the interface. We consider the cases of both uniform and non-uniform distributions of densities and the effect of including gravity. We show that the f-mode exists in a restricted band of horizontal wavenumber. In the subsequent chapters we consider the effect of compressibility on surface waves. The media either side of the interface are taken to be isothermal. In the absence of gravity the interface may support one or two surface modes determined by the relative temperatures and magnetism of the two media. This case is studied in Chapter 3 where phase-speeds and penetration depths of the waves and the associated pressure perturbations are investigated for a variety of field strengths and sound speeds. In Chapters 4 and 5 we consider the effect of gravity on the compressible modes described in Chapter 3. In Chapter 4 an exact dispersion relation is obtained for the case of a constant Alfven speed, whilst in Chapter 5 the case of a uniform magnetic field is considered. In the absence of the magnetic field the transcendental dispersion relation may be reduced to a polynomial. This polynomial possesses two acceptable solutions, only one of which may exist at any given circumstance depending on the densities either side of the interface. If the gas density within the field exceeds that in the field-free medium, then the f-mode may propagate; otherwise, a magnetic surface gravity mode propagates. As in the incompressible case, the f-mode exists in a restricted band of horizontal wavenumber. An analytical form for the wave speed of the f-mode is obtained for small values of the Alfven speed. It is shown that the f-mode is related to the fast magnetoacoustic surface wave, merging into that mode at short wavelengths.
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Manenti, Riccardo. "Circuit quantum acoustodynamics with surface acoustic waves." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:3b29e5b7-cb1d-4588-81ec-d1aa659cbf6e.
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A highly successful architecture for the exchange of single quanta between coupled quantum systems is circuit quantum electrodynamics (QED), in which the electrical interaction between a qubit and a high-quality microwave resonator offers the possibility to reliably control, store, and read out quantum bits of information on a chip. This architecture has also been implemented with mechanical resonators, showing that a vibrational mode can in principle be manipulated via a coupled qubit. The work presented in this thesis consists of realising an acoustic version of circuit QED that we call circuit quantum acoustodynamics (QAD), in which a superconducting qubit is piezoelectrically coupled to an acoustic cavity based on surface acoustic waves (SAWs). Designing and building this novel platform involved the following main accomplishments: a systematic characterisation of SAW resonators at low temperatures; successfully developing a recipe for the fabrication of Josephson junction on quartz and diamond; measuring the coherence time of superconducting 3D transmon qubits on these substrates and demonstrating the dispersive coupling between a SAW cavity and a qubit on a planar geometry. This thesis presents evidence of the coherent interaction between a SAW cavity and a superconducting qubit in several ways. First of all, a frequency shift of the mechanical mode as a function of qubit frequency is observed. We also measure the acoustic Stark shift of the qubit due to the population of the SAW cavity. The extracted coupling is in agreement with theoretical expectations. A time delayed acoustic Stark shift serves to further demonstrate that the Stark shifts that we observe are indeed due to the acoustic field of the SAW mode. The dispersive coupling between these two quantum systems offers the possibility to perform qubit spectroscopy using the SAW resonator as readout component, indicating that these acoustic resonators can, in principle, be adopted as an alternative qubit readout scheme in quantum information processors. We finally present preliminary measurements of the direct coupling between a SAW resonator and a transmon on diamond, suggesting that strong coupling can in principle be obtained.
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AURELIO, DANIELE. "Integrated Optics Based on Bloch Surface Waves." Doctoral thesis, Università degli studi di Pavia, 2019. http://hdl.handle.net/11571/1243688.
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Negli ultimi decenni, la ricerca nell'ambito della fotonica integrata ha fatto grandi passi avanti, e ha portato sia a nuova fisica che ad apparecchiature tecnologiche che ora permeano le nostre vite. Nella plasmonica, in particolare, si manipola la luce su scale nanometriche sfruttando le proprietà ottiche di nanostrutture metalliche. I plasmoni di superficie (SPP) sono oscillazioni di densità di carica che si propagano lungo l'interfaccia tra un metallo ed un mezzo dielettrico e la cui costante di propagazione dipende dalla funzione dielettrica sia del metallo che del dielettrico, e dunque ne eredita la natura complessa: nel dettaglio, la parte immaginaria è legata all'attenuazione lungo la direzione di propagazione. Queste perdite intrinseche limitano l'utilizzo di tecnologie basate su SPP. Per superare queste limitazioni, si può ricorrere a mezzi dielettrici. Un multistrato periodico, ad esempio, si comporta come uno specchio perfetto, con riflettanza unitaria per tutte le frequenze e i vettori d'onda all'interno del suo bandgap fotonico (PBG); tuttavia, un adeguato troncamento della periodicità può introdurre stati fotonici all'interno del PBG: questi modi vivono sia sotto la linea di luce del mezzo esterno che dentro il PBG, e sono noti come onde di Bloch di superficie (BSW). I BSW sono attraenti per via dei loro intensi campi superficiali: la maggior parte della luce in un BSW è concentrata in prossimità della superficie del multistrato, essendo confinata per riflessione totale interna (TIR) dal lato dielettrico e da un PBG dal lato del multistrato: questo dà origine a profili di modo molto piccati, che hanno portato i BSW ad essere considerati alla stregua di "plasmoni dielettrici". Tuttavia, al contrario degli SPP, un adeguato design del multilayer sottostante permette l'esistenza di BSW polarizzati sia TE che TM. Un'applicazione on-chip efficace dei BSW si scontra però ancora con delle questioni aperte. In primo luogo, non è chiaro se i BSW offrano un vantaggio in termini di field enhancement o di volume modale rispetto a soluzioni più semplici basate su TIR: la maggior parte dei ricercatori dà per scontato che esista questo vantaggio, ma prima d'ora non è mai stato dimostrato. Un altro interrogativo è come un BSW interagisca con un grating, una modulazione monodimensionale dell'indice di rifrazione nella direzione di propagazione. Questo risulta importante nell'ottica di ottimizzare lo schema di accoppiamento, che ad oggi è perlopiù basato su prisma. Inoltre, si è ancora alla ricerca di risuonatori ad anello per BSW. Solo un paio di anni fa è stata pubblicata la prima dimostrazione sperimentale di un risuonatore a disco per BSW; tuttavia, nell'ottica di diminuire il volume modale del BSW, ricorrere a risuonatori ad anello sembra la strada maestra. Le caratteristiche dei risuonatori ad anelli per BSW sono state studiare teoricamente, ma un'analisi sperimentale completa delle loro performance non è ancora stata pubblicata. In ultimo, va affrontato il discorso del confinamento 3D dei BSW, dal momento che non sono mai state osservate cavità fotoniche per BSW.
Questa tesi di dottorato rappresenta il mio tentativo di dare una risposta ad alcune di queste domande. Ho introdotto una procedura di ottimizzazione che, scelto un set di indici di rifrazione, fornisce a priori il volume modale minimo e il campo alla superficie massimo ottenibili con un BSW; ho anche analizzato la dispersione dei modi guidati supportati da un grating 1D costruito su un multistrato periodico troncato in funzione dei parametri geometrici del grating; ho anche riportato i nostri dati relativi alla prima dimostrazione sperimentale di un risuonatore ad anello in silicio poroso, frutto della collaborazione con il gruppo della prof.ssa Weiss della Vanderbilt University, in Tennessee. In conclusione, ho riportato la nostra strategia di design per una cavità nanobeam per BSW, confermandone la validità con simulazioni FDTD 2D.Over the last decades, the research and development of chip-scale photonics has made giant leaps forward, and has brought about exciting new physics and technological devices that now permeate our lives. Plasmonics is one such field, where light is manipulated at the nanoscale by exploiting the optical properties of metallic nanostructures. Surface plasmon polaritons (SPPs) are charge-density oscillations that propagate along the interface between a metal and a dielectric cladding. The SPP propagation constant depends on the dielectric functions of both the dielectric and metallic media, and thus it inherits the complex nature of these figures: in particular, its imaginary part entails attenuation along the direction of propagation. These intrinsic losses plague metallic systems and hinder the scope of SPP-based technology. To overcome this limitation, one can forgo metals and resort to dielectric media. For example, an infinite periodic multilayer behaves as a perfect mirror with unit reflectivity for all the frequencies and wave vectors inside its photonic band gap (PBG); however, a proper truncation of the multilayer periodicity may introduce photonic states inside the PBG: these modes living both below the light line of the external material and inside the PBG of a 1D photonic crystal are known as Bloch Surface Waves (BSWs). BSWs are particularly appealing due to their intense surface fields: most of the light in a BSW is trapped near the surface of the multilayer since light is confined by total internal reflection (TIR) on the dielectric side and by a PBG in the stacking direction: this allows for strongly peaked mode profiles, which is why BSWs have been considered as "dielectric plasmons". However, unlike SPPs, with proper design of the supporting multilayer both transverse-electric and transverse-magnetic polarized BSWs may exist. A thorough on-chip application of BSWs is still limited by a number of open questions. In the first place, the question whether BSWs actually have a strategic advantage in terms of field enhancement or modal volume with respect to simpler TIR-based solutions is surprisingly still unanswered; most researchers simply take this advantage for granted, but no proof has ever been published in the scientific literature. Another open question is how BSWs interact with a grating, a 1D refractive index modulation along the direction of propagation. This is important with a view to optimizing the coupling scheme, which until now has mostly been prism-based. Moreover, microring resonators based on BSWs are still being actively researched. The topic seems to be particularly fertile, as a couple of years ago an experimental demonstration of a BSW disk resonator was published; however, with a view to further reducing the modal volume of the BSW, resorting to a ring resonator seems inevitable. Features of BSW ring resonators have been studied theoretically, but a thorough experimental analysis of their behavior has not been carried out yet. Finally, a point that should be addressed is how full 3D confinement of BSWs could be achieved, as no photonic cavity has ever been demonstrated for BSWs. This PhD thesis represents my attempt to answer some of these open questions. I introduced a general optimization procedure that, given a set of refractive indices, allows one to understand a priori the minimum modal length and maximum surface electric field achievable with a BSW; I also analyzed the dispersion of guided modes supported by a 1D grating built on a 1D truncated periodic multilayer as a function of the geometrical parameters of the grating; I also reported our data on the first experimental demonstration of a porous silicon BSW ring resonator, which represents a collaboration with the Weiss group from Vanderbilt University in Tennessee. In the last chapter, I also reported a novel design strategy for BSW-based nanobeam cavities, whose validity has been confirmed by 2D FDTD simulations.
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BIGNARDI, Samuel. "Complete Waveform Inversion Approach To Seismic Surface Waves And Adjoint Active Surfaces." Doctoral thesis, Università degli studi di Ferrara, 2011. http://hdl.handle.net/11392/2388824.
Full textAbstract:
The idea to exploit the dispersive mechanism of surface waves as a probing tool for investigating
subsurface structure was introduced about 30 years ago, and afterwards a very intense research field
has developed. Currently many methods known generally as Surface Wave Methods exist, and are well
established, most of them assuming layered or depth dependent ground models. In most cases the
parallel layer assumption is correct because the soil structure is expected to negligibly depart from a
layered structure at a typical surface testing scale for engineering and geotechnical purposes however to
exploit the amount of information achievable, it is necessary to extend the research, relaxing at least
one of the underlying model assumptions.
Indeed in classical SWM’s, surface waves are assumed to be Rayleigh waves, this means that a parallel
layered model has been implicitly assumed. As a consequence search for a soil model geometry other
than the assumed one can only result in slight perturbations. The only possible deduction is that
overcoming limitations of layered models requires to exploit P and S waves which are indeed general
solutions of the elastodynamic problem. Geometry can then be retrived by a complete waveform
inversion based on a forward model capable of successfully reproducing all of the features of the
displacement field in presence of complex scattering phenomena. In this research effort an inversion
approach has been introduced which exploits the
Boundary Element Method as forward model. Such approach is appealing from a theoretical point of
view and is computationally efficient. Although in the present work a monochromatic signal traveling
in a system constituted by a layer over an half space was investigated, this method is suitable for any
number of layers, and multi-frequency environments. The boundary element approach can be easily
generalized to three-dimensional modeling; moreover viscoelasticity can be introduced by the elasticviscoelastic
principle of correspondence. Finally BEM can be easily implemented for parallel
computing architecture. Synthetic cases of high and low impedance Jump were investigated for typical
SWM setups and a first example of application on real data was performed. Finally an elegant analytic
form of the minimization flow named Adjoint Active Surfaces was obtained combining Computer
Vision technique of Active surfaces and the Adjoint Field method.
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Halliday, David Fraser. "Surface wave interferometry." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3976.
Full textAbstract:
This thesis concerns the application of seismic interferometry to surface waves. Seismic interferometry is the process by which the wavefield between two recording locations is estimated, resulting in new recordings at one location as if a source had been placed at the other. Thus, in surface-wave interferometry, surface waves propagating between two receiver locations are estimated as if one receiver had recorded the response due to a source of surface-wave energy at the other receiver. In global and engineering seismology new surface-wave responses can allow for imaging of the subsurface, and in exploration seismology it has been proposed that these new surface-wave responses can allow for the prediction and removal of socalled ground-roll (surface waves that are treated as noise). This thesis presents a detailed analysis of surface-wave interferometry: using a combination of modelling studies, real-data studies, and theoretical analyses the processes involved in the application of interferometry to complex (both multi-mode and scattered) surface waves are revealed. These analyses identify why surface waves are often dominant in the application of interferometry, where errors may be introduced in the application of surface-wave interferometry, and how interferometry may be processed in such a way as to minimise those (and other) errors. This allows for the proposal of new data-processing strategies in the application of seismic interferometry to surface waves, potentially resulting in improved surface-wave estimates. Much of the work in this thesis focuses on the use of seismic interferometry to predict and subtract surface waves in land-seismic exploration surveys. Using insights from the presented analyses it is shown that seismic surface waves can be successfully predicted and removed from land-seismic data using an interferometric approach. However, the work in this thesis is not only limited to applications in exploration seismology. In addition to the ground-roll removal method, improved estimates of higher-mode and scattered surfaces waves may allow for more advanced imaging algorithms to be used in conjunction with seismic interferometry. Also, as a consequence of the analysis presented a Generalized Optical Theorem for Surface Waves is derived. This highlights a link between seismic interferometry and the optical theorem and may allow for further application of optical theorems in seismology.
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Orozco, M. Catalina (Maria Catalina). "Inversion Method for Spectral Analysis of Surface Waves (SASW)." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5124.
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This research focuses on estimating the shear wave velocity (Vs) profile based on the dispersion curve obtained from SASW field test data (i.e., inversion of SASW data). It is common for the person performing the inversion to assume the prior information required to constrain the problem based on his/her own judgment. Additionally, the Vs profile is usually shown as unique without giving a range of possible solutions. For these reasons, this work focuses on: (i) studying the non-uniqueness of the solution to the inverse problem; (ii) implementing an inversion procedure that presents the estimated model parameters in a way that reflects their uncertainties; and (iii) evaluating tools that help choose the appropriate prior information.
One global and one local search procedures were chosen to accomplish these purposes: a pure Monte Carlo method and the maximum likelihood method, respectively. The pure Monte Carlo method was chosen to study the non-uniqueness by looking at the range of acceptable solutions (i.e., Vs profiles) obtained with as few constraints as possible. The maximum likelihood method was chosen because it is a statistical approach, which enables us to estimate the uncertainties of the resulting model parameters and to apply tools such as the Bayesian criterion to help select the prior information objectively.
The above inversion methods were implemented for synthetic data, which was produced with the same forward algorithm used during inversion. This implies that all uncertainties were caused by the nature of the SASW inversion problem (i.e., there were no uncertainties added by experimental errors in data collection, analysis of the data to create the dispersion curve, layered model to represent a real 3-D soil stratification, or wave propagation theory). At the end of the research, the maximum likelihood method of inversion and the tools for the selection of prior information were successfully used with real experimental data obtained in Memphis, Tennessee.
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Morris-Thomas, Michael. "An investigation into wave run-up on vertical surface piercing cylinders in monochromatic waves." University of Western Australia. School of Oil and Gas Engineering, 2003. http://theses.library.uwa.edu.au/adt-WU2004.0010.
Full textAbstract:
[Formulae and special characters can only be approximated here. Please see the pdf version of the abstract for an accurate reproduction.] Wave run-up is the vertical uprush of water when an incident wave impinges on a free- surface penetrating body. For large volume offshore structures the wave run-up on the weather side of the supporting columns is particularly important for air-gap design and ultimately the avoidance of pressure impulse loads on the underside of the deck structure. This investigation focuses on the limitations of conventional wave diffraction theory, where the free-surface boundary condition is treated by a Stokes expansion, in predicting the harmonic components of the wave run-up, and the presentation of a simplified procedure for the prediction of wave run-up. The wave run-up is studied on fixed vertical cylinders in plane progressive waves. These progressive waves are of a form suitable for description by Stokes' wave theory whereby the typical energy content of a wave train consists of one fundamental harmonic and corresponding phase locked Fourier components. The choice of monochromatic waves is indicative of ocean environments for large volume structures in the diffraction regime where the assumption of potential flow theory is applicable, or more formally A/a < Ο(1) (A and a being the wave amplitude and cylinder radius respectively). One of the unique aspects of this work is the investigation of column geometry effects - in terms of square cylinders with rounded edges - on the wave run-up. The rounded edges of each cylinder are described by the dimensionless parameter rc/a which denotes the ratio of edge corner radius to half-width of a typical column with longitudinal axis perpendicular to the quiescent free-surface. An experimental campaign was undertaken where the wave run-up on a fixed column in plane progressive waves was measured with wire probes located close to the cylinder. Based on an appropriate dimensional analysis, the wave environment was represented by a parametric variation of the scattering parameter ka and wave steepness kA (where k denotes the wave number). The effect of column geometry was investigated by varying the edge corner radius ratio within the domain 0 <=rc/a <= 1, where the upper and lower bounds correspond to a circular and square shaped cylinder respectively. The water depth is assumed infinite so that the wave run-up caused purely by wave-structure interaction is examined without the additional influence of a non-decaying horizontal fluid velocity and finite depth effects on wave dispersion. The zero-, first-, second- and third-harmonics of the wave run-up are examined to determine the importance of each with regard to local wave diffraction and incident wave non-linearities. The modulus and phase of these harmonics are compared to corresponding theoretical predictions from conventional diffraction theory to second-order in wave steepness. As a result, a basis is formed for the applicability of a Stokes expansion to the free-surface boundary condition of the diffraction problem, and its limitations in terms of local wave scattering and incident wave non-linearities. An analytical approach is pursued and solved in the long wavelength regime for the interaction of a plane progressive wave with a circular cylinder in an ideal fluid. The classical Stokesian assumption of infinitesimal wave amplitude is invoked to treat the free-surface boundary condition along with an unconventional requirement that the cylinder width is assumed much smaller than the incident wavelength. This additional assumption is justified because critical wavelengths for wave run-up on a fixed cylinder are typically much larger in magnitude than the cylinder's width. In the solution, two coupled perturbation schemes, incorporating a classical Stokes expansion and cylinder slenderness expansion, are invoked and the boundary value problem solved to third-order. The formulation of the diffraction problem in this manner allows for third-harmonic diffraction effects and higher-order effects operating at the first-harmonic to be found. In general, the complete wave run-up is not well accounted for by a second-order Stokes expansion of the free-surface boundary condition and wave elevation. This is however, dependent upon the coupling of ka and kA. In particular, whilst the modulus and phase of the second-harmonic are moderately predicted, the mean set-up is not well predicted by a second-order Stokes expansion scheme. This is thought to be caused by higher than second-order non-linear effects since experimental evidence has revealed higher-order diffraction effects operating at the first-harmonic in waves of moderate to large steepness when k < < 1. These higher-order effects, operating at the first-harmonic, can be partially accounted for by the proposed long wavelength formulation. For small ka and large kA, subsequent comparisons with measured results do indeed provide a better agreement than the classical linear diffraction solution of Havelock (1940). To account for the complete wave run-up, a unique approach has been adopted where a correction is applied to a first-harmonic analytical solution. The remaining non-linear portion is accounted for by two methods. The first method is based on regression analysis in terms of ka and kA and provides an additive correction to the first-harmonic solution. The second method involves an amplification correction of the first-harmonic. This utilises Bernoulli's equation applied at the mean free-surface position where the constant of proportionality is empirically determined and is inversely proportional to ka. The experimental and numerical results suggest that the wave run-up increases as rc/a--› 0, however this is most significant for short waves and long waves of large steepness. Of the harmonic components, experimental evidence suggests that the effect of a variation in rc/a on the wave run-up is particularly significant for the first-harmonic only. Furthermore, the corner radius effect on the first-harmonic wave run-up is well predicted by numerical calculations using the boundary element method. Given this, the proposed simplified wave run-up model includes an additional geometry correction which accounts for rc/a to first-order in local wave diffraction. From a practical view point, it is the simplified model that is most useful for platform designers to predict the wave run-up on a surface piercing column. It is computationally inexpensive and the comparison of this model with measured results has proved more promising than previously proposed schemes.
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Reese, Owein. "Homogenization of acoustic wave propagation in a magnetorheological fluid." Link to electronic thesis, 2004. http://www.wpi.edu/Pubs/ETD/Available/etd-0430104-101629.
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Kocaoglu, Argun H. "A new method for modeling surface wave propagation in heterogeneous media." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/25716.
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Kukulka, Tobias. "The effect of breaking waves on a coupled model of wind and ocean surface waves." View online ; access limited to URI, 2006. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3248233.
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Kalinski, Michael E. "Determination of in situ V[subscript s] and G[subscript max] using surface wave measurements in cased and uncased boreholes /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Law, Owen Yi Kei. "Experiments on evolution of surface gravity waves from deep to shallow waters /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?MECH%202004%20LAW.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 57-59). Also available in electronic version. Access restricted to campus users.
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Yoon, Sungsoo. "Array-Based Measurements of Surface Wave Dispersion and Attenuation Using Frequency-Wavenumber Analysis." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7246.
Full textAbstract:
Surface wave methods have been used to determine dynamic properties of near-surface soils in geotechnical engineering for the past 50 years. Although the capabilities of engineering surface wave methods have improved in recent years due to several advances, several issues including (1) near-field effects, (2) combined active and passive measurements, and (3) accurate measurements of surface wave attenuation still require study to further improve the capabilities of modern surface wave methods.
Near-field effects have been studied for traditional surface wave methods with two receivers and several filtering criteria to mitigate the effects have been recommended. However, these filtering criteria are not applicable to surface wave methods with multiple receivers. Moreover, the criteria are not quantitatively based and do not account for different types of soil profiles, which strongly influence near-field effects. A new study of near-field effects on surface wave methods with multiple receivers was conducted with numerical and experimental methods. Two normalized parameters were developed to capture near-field effects. Quantitatively based near-field effect criteria for an ideal homogeneous half-space and three typical soil profiles are presented.
Combining active and passive surface wave measurements allows developing a shear wave velocity profile to greater depth without sacrificing the near-surface resolution offered by active measurements. Generally, active and passive measurements overlap in the frequency range from approximately 4 to 10 Hz, and there are often systematic differences between the two measurements. The systematic errors in active and passive surface wave methods were explored to explain and resolve the differences, allowing for a more accurate composite dispersion curve.
The accuracy of measured surface wave attenuation is improved by properly accounting for (1) geometric spreading, (2) near-field effects, and (3) ambient noise. In this study, a traditional estimation method and a frequency-wavenumber method utilizing sub-arrays were investigated using displacement data from numerical simulations, focusing on near-field and ambient noise effects. Detailed procedures for the frequency-wavenumber estimation method are developed based on a study of the primary factors affecting attenuation estimates. The two methods are also evaluated using experimental displacement data obtained from surface wave field measurements with three different arrays.
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Xu, Liwei. "Computational methods for a class of problems in acoustic, elastic and water waves." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 203 p, 2009. http://proquest.umi.com/pqdweb?did=1833647381&sid=12&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Chan, Tak-yee Andy, and 陳德儀. "The interaction of laminar far wake with a free surface." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B30101098.
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