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Dissertations / Theses on the topic 'Three wave interaction'
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1
Baker, Scott. "Physical and numerical modelling of wave interaction with a three-dimensional submerged structure." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27954.
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Submerged structures are frequently used in coastal engineering applications, such as tunnel and pipeline protection works, breakwaters, and artificial reefs. Although a significant number of research works have focused on low-crested structures, there is far less research into deeply submerged structures. In most research, lightly-sloped, uniform cross-sectioned submerged structures with specific crest elevations are considered.
The present thesis deals with the three-dimensional physical and numerical modelling of the interaction of irregular waves with a large-scale three-dimensional submerged structure. It aims to advance the understanding of the structure's influence on the irregular wave field, the wave-induced velocities along the structure crest, and the wave-induced currents. The ability of a nonlinear Boussinesq wave model to simulate these processes is also investigated and assessed.
Analysis was performed on a multitude of data, including---but not limited to---wave heights, wave periods, wave energy spectra, energy transfer functions, reflection analyses, and wave-induced velocities. In general, the analysis and comparison performed showed that the numerical model provided a modestly accurate representation of the physical modelling results.
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Siegel, Ariella. "Why Is This Wave Different From All Other Waves? Jewish Miami: The Changing Face of Institutional Interaction in Three Phases." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/700.
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This thesis presents an historical overview of the immigration/migration process that led to the institutional establishment of a vibrant Jewish community in Miami, Florida. By doing so, this thesis suggests three distinct, yet interconnected waves of immigration/migration: the first wave was from the 1920s until the 1950s and was comprised primarily of Northeastern Jewish migrants; the second wave was from the 1960s until the 1970s and was comprised of Cuban-Jewish immigrants; and the third wave began in the 1970s and continues until today, and is comprised of the Latin American Jewish immigrants. These waves are studied by considering (1) the demographics of each individual wave and the corresponding reasons for migration to Miami; (2) which institutions were established within each wave and the motivation for their establishment; and (3) the different dynamic each immigrant/migrant cohort had with the institutions in the Jewish community. It also explores institutional evolution within each wave and connects the waves together to reveal a multi-faceted construction of the Jewish community of Miami as it is today.
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Tang, Chun Quan. "Time domain three-dimensional fully nonlinear computations for body-wave interaction in a dynamic visualization architecture." Thesis, University of Strathclyde, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428846.
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Ogawa, Hideaki. "Experimental and analytical investigation of transonic shock-wave/boundary-layer interaction control with three-dimensional bumps." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612897.
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Singh, Reetu. "Development of Three Dimensional Fluid-Structure Interaction Models for the Design of Surface Acoustic Wave Devices: Application to Biosensing and Microfluidic Actuation." Scholar Commons, 2009. http://scholarcommons.usf.edu/etd/3677.
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Surface acoustic wave (SAW) devices find uses in a plethora of applications including
but not limited to chemical, biological sensing, and microfluidic actuation. The primary aim of
this dissertation is to develop a SAW biosensor, capable of simultaneous detection of target
biomarkers in fluid media at concentrations of picogram/ml to nanogram/ml levels and removal
of non-specific proteins from sensor surface using the process of acoustic streaming, for potential
chemical sensing, medical, and clinical diagnostic applications. The focus is on the development
of three dimensional finite element structural and fluid-structure interaction models to study wave
propagation and acoustic actuation of fluids in a SAW biosensor. This work represents a
significant improvement in understanding fluid flow over SAW devices, over the currently
available continuum model of Nyborg. The developed methodology includes use of a novel
substrate, namely, Langasite coupled with various combinations of novel multidirectional
interdigital transducer (IDT) configurations such as orthogonal, focused IDTs as well as sensor
surface modifications, such as micro-cavities. The current approach exploits the capability of the
anisotropic piezoelectric crystal to launch waves of different characteristics in different
directions, which can be put to the multiple uses including but not limited to sensing via
shear
horizontal waves and biofouling elimination via
Rayleigh wave induced acoustic streaming.
Orthogonal IDTs gives rise to constructive interference, thereby enhancing the magnitudes of
device displacements and fluid velocities. The net effect is an increase in device sensitivity and
acoustic streaming intensity. The use of micro-cavities in the delay path provides a synergistic
effect, thereby further enhancing the device sensitivity and streaming intensity. Focused IDTs are
found to enhance the device displacements and fluid velocities, while focusing the device
displacements and fluid motion at the device focal point, thereby enhancing the SAW device
biosensing performance. The work presented in this dissertation has widespread and immediate
use for enhancing sensor sensitivity and analyte discrimination capabilities as well as biofouling
removal in medical diagnostic applications of SAW sensors. This work also has a broad relevance
to the sensing of multiple biomarkers in medical applications as well as other technologies
utilizing these devices such as microfluidic actuation.
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Mak, William Chi Keung Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Coupled Solitary Waves in Optical Waveguides." Awarded by:University of New South Wales. Electrical Engineering and Telecommunications, 1998. http://handle.unsw.edu.au/1959.4/17494.
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Soliton states in three coupled optical waveguide systems were studied: two linearly coupled waveguides with quadratic nonlinearity, two linearly coupled waveguides with cubic nonlinearity and Bragg gratings, and a quadratic nonlinear waveguide with resonant gratings, which enable three-wave interaction. The methods adopted to tackle the problems were both analytical and numerical. The analytical method mainly made use of the variational approximation. Since no exact analytical method is available to find solutions for the waveguide systems under study, the variational approach was proved to be very useful to find accurate approximations. Numerically, the shooting method and the relaxation method were used. The numerical results verified the results obtained analytically. New asymmetric soliton states were discovered for the coupled quadratically nonlinear waveguides, and for the coupled waveguides with both cubic nonlinearity and Bragg gratings. Stability of the soliton states was studied numerically, using the Beam Propagation Method. Asymmetric couplers with quadratic nonlinearity were also studied. The bifurcation diagrams for the asymmetric couplers were those unfolded from the corresponding diagrams of the symmetric couplers. Novel stable two-soliton bound states due to three-wave interaction were discovered for a quadratically nonlinear waveguide equipped with resonant gratings. Since the coupled optical waveguide systems are controlled by a larger number of parameters than in the corresponding single waveguide, the coupled systems can find a much broader field of applications. This study provides useful background information to support these applications.
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Xue, Ming 1967. "Three-dimensional fully-nonlinear simulations of waves and wave body interactions." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10216.
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Fares, Reine. "Techniques de modélisation pour la conception des bâtiments parasismiques en tenant compte de l’interaction sol-structure." Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4103/document.
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La conception des bâtiments selon le code sismique européen ne prend pas en compte les effets de l'interaction sol-structure (ISS). L'objectif de cette recherche est de proposer une technique de modélisation pour prendre en compte l’ISS et l'interaction structure-sol-structure (ISSS). L'approche de propagation unidirectionnelle d’une onde à trois composantes (1D-3C) est adoptée pour résoudre la réponse dynamique du sol. La technique de modélisation de propagation unidirectionnelle d'une onde à trois composantes est étendue pour des analyses d'ISS et ISSS. Un sol tridimensionnel (3D) est modélisé jusqu'à une profondeur fixée, où la réponse du sol est influencée par l’ISS et l’ISSS, et un modèle de sol 1-D est adopté pour les couches de sol plus profondes, jusqu'à l'interface sol-substrat. Le profil de sol en T est assemblé avec une ou plusieurs structures 3-D de type poteaux-poutres, à l’aide d’un modèle par éléments finis, pour prendre en compte, respectivement, l’ISS et l’ISSS dans la conception de bâtiments. La technique de modélisation 1DT-3C proposée est utilisée pour étudier les effets d’ISS et analyser l'influence d'un bâtiment proche (l'analyse d’ISSS), dans la réponse sismique des structures poteaux-poutres. Une analyse paramétrique de la réponse sismique des bâtiments en béton armé est développée et discutée pour identifier les paramètres clé du phénomène d’ISS, influençant la réponse structurelle, à introduire dans la conception de bâtiments résistants aux séismes. La variation de l'accélération maximale en haut du bâtiment avec le rapport de fréquence bâtiment / sol est tracée pour plusieurs bâtiments, chargés par un mouvement à bande étroite, excitant leur fréquence fondamentale. Dans le cas de sols et de structures à comportement linéaire, une tendance similaire est obtenue pour différents bâtiments. Cela suggère l'introduction d'un coefficient correcteur du spectre de réponse de dimensionnement pour prendre en compte l’ISS. L'analyse paramétrique est répétée en introduisant l'effet de la non-linéarité du sol et du béton armé. La réponse sismique d'un bâtiment en béton armé est estimée en tenant compte de l'effet d'un bâtiment voisin, pour un sol et des structures à comportement linéaire, dans les deux cas de charge sismique à bande étroite excitant la fréquence fondamentale du bâtiment cible et du bâtiment voisin. Cette approche permet une analyse efficace de l'interaction structure-sol-structure pour la pratique de l'ingénierie afin d'inspirer la conception d'outils pour la réduction du risque sismique et l'organisation urbaine<br>Building design according to European seismic code does not consider the effects of soil-structure interaction (SSI). The objective of this research is to propose a modeling technique for SSI and Structure-Soil-Structure Interaction (SSSI) analysis. The one-directional three-component (1D-3C) wave propagation approach is adopted to solve the dynamic soil response. The one-directional three-component wave propagation model is extended for SSI and SSSI analysis. A three-dimensional (3-D) soil is modeled until a fixed depth, where the soil response is influenced by SSI and SSSI, and a 1-D soil model is adopted for deeper soil layers until the soil-bedrock interface. The T-soil profile is assembled with one or more 3-D frame structures, in a finite element scheme, to consider, respectively, SSI and SSSI in building design. The proposed 1DT-3C modeling technique is used to investigate SSI effects and to analyze the influence of a nearby building (SSSI analysis), in the seismic response of frame structures. A parametric analysis of the seismic response of reinforced concrete (RC) buildings is developed and discussed to identify the key parameters of SSI phenomenon, influencing the structural response, to be introduced in earthquake resistant building design. The variation of peak acceleration at the building top with the building to soil frequency ratio is plotted for several buildings, loaded by a narrow-band motion exciting their fundamental frequency. In the case of linear behaving soil and structure, a similar trend is obtained for different buildings. This suggests the introduction of a corrective coefficient of the design response spectrum to take into account SSI. The parametric analysis is repeated introducing the effect of nonlinear behaving soil and RC. The seismic response of a RC building is estimated taking into account the effect of a nearby building, for linear behaving soil and structures, in both cases of narrow-band seismic loading exciting the fundamental frequency of the target and nearby building. This approach allows an easy analysis of structure-soil-structure interaction for engineering practice to inspire the design of seismic risk mitigation tools and urban organization
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Yan, Hongmei. "Computations of fully nonlinear three-dimensional wave-body interactions." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61616.
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Thesis (Ph. D. in Ocean Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references.<br>Nonlinear effects in hydrodynamics of wave-body interaction problems become critically important when large-amplitude body motions and/or extreme surface waves are involved. Accurate prediction and understanding of these fully nonlinear effects are still challenges in the design of surface ships and marine structures, owing to the complexity of the hydrodynamic problem itself and limited computational facilities. This research is focused on: (i) development of a highly efficient numerical scheme for the computation of fully-nonlinear three-dimensional wave-body interactions; and (ii) investigation of several highly nonlinear wave-body interaction problems for understanding associated key nonlinear effects. A highly efficient high-order boundary element method is developed based on the framework of the quadratic boundary element method (QBEM) for the boundary integral equation and using the pre-corrected fast Fourier transform (PFFT) algorithm to accelerate the evaluation of far-field influences of source and/or normal dipole distributions on boundary elements. The resulting numerical scheme reduces the computational effort of solving the boundary-value problem from O(N 2 ~3) (with the traditional boundary element methods) to O(N ln N) where N represents the total number of boundary unknowns. Combining with the mixed-Eulerian-Lagrangian (MEL) approach for nonlinear free surface tracking, we develop an efficient and accurate initial boundary value problem (IBVP) solver, PFFT-QBEM, which allows for practical simulations of fully nonlinear three-dimensional wave-body interaction problems. Three nonlinear wave-body interaction problems, which are of scientific interest and practical importance, are investigated in detail: water surface impact of threedimensional objects, cavity dynamics in water entries, and coupled unstable motions of floating structures in waves. For the water impact problem, with the development of an adaptive jet flow treatment and an effective approach for accurately tracking water-body separation point/line, we obtain a thorough understanding of the gravity effect on the characteristics of slamming pressure/load on the object and free-surface profiles. For the cavity problem, we investigate the formation and evolution of an air cavity behind an object dropped into water (from air) at relatively low Froude numbers where the inertia and gravity effects are comparable. A theoretical solution is newly derived based on a matched asymptotic approach and a fully nonlinear numerical simulation is carried out, for the description of the kinematics and dynamics of the air cavity. Satisfactory quantitative comparisons are obtained among the theoretical predictions, numerical simulations, and existing experimental measurements for the dependence of cavity shape and closure time/height on Froude number and body geometry. For floating structures in waves, our focus is on the understanding of the fundamental mechanism and basic characteristics for coupled unstable heave-pitch motions of floating platforms/vessels. Through stability analyses, we identify that the second-order difference-frequency interaction between surface waves and body motions is the key mechanism for the excitation of unstable resonant motions. Fully nonlinear simulations are conducted to study the development of large-amplitude body motions and investigate quantitatively the dependence of the instability on related physical parameters, such as incident wave amplitude and phase, frequency detuning, body geometry, and system damping. Theoretical analyses and numerical simulations are verified by comparison to available experiments for the coupled unstable motions of a deep draft caisson vessel (DDCV).<br>by Hongmei Yan.<br>Ph.D.in Ocean Engineering
10
Murray, Neil Paul. "Three-dimensional turbulent shock-wave : boundary-layer interactions in hypersonic flows." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/7963.
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Chpoun, Amer. "Contribution a l'etude d'ecoulements hypersoniques (m=5) sur une rampe de compression en configuration 2-d et 3-d." Paris 6, 1988. http://www.theses.fr/1988PA06A005.
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Etude experimentale de l'influence de l'ecoulement transversal sur les distributions du flux thermique et de la pression parietale. Determination des grandeurs caracteristiques de la zone de decollement. Etude de l'apparition de la transition dans la zone du decollement en fonction du nombre de reynolds. Solution numerique pour la distribution de pression dans le cas de l'interaction laminaire
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Harris, Jamie. "The kinematics, dynamics and statistics of three-wave interactions in models of geophysical flow." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/58419/.
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We study the dynamics, kinematics and statistics of resonant and quasiresonant three-wave interactions appearing in models of geophysical flow. In these dispersive wave systems, the phenomenon of nonlinear resonance broadening plays a significant role across all three different branches of wave turbulence theory: from the statistical, to the discrete, and even the mesoscopic, formed as an intermediate regime between the two. The principal aim of this thesis is to understand the processes by which resonance broadening can induce a transition between each of these three different regimes. Beginning with the discrete case, we study two variants of the isolated triad: one with a constant additive forcing term; and the other in the presence of detuning. We provide a detailed analysis of both of these systems, covering their integrability and boundedness properties, showing that for almost all initial conditions the motion remains quasi-periodic and periodic respectively. Interestingly, we show that moderate amounts of detuning can actually promote energy exchange, increase the period and in rare instances cease to be periodic at all; each of these statements are contrary to what was previously thought. This motivates a more detailed study into the kinematics of resonance broadening. By analysing how the set of quasi-resonant modes develops under increased broadening, we show that a percolation-like transition exists, independent of the dispersion relationship used. At critical levels of broadening, we see the emergence of a single quasi-resonant cluster that begins to dominate the entire system. We argue that the formation of this cluster provides a way of characterising the turbulent state of the system, distinguishing between the discrete and statistical regimes. Through direct numerical simulation of the Charney-Hasegawa-Mima equation, we then assess whether this view is truly representative of the underlying dynamics. Here we find that the generation of quasi-resonantly excited modes can be detected through the statistical measures of total correlation and mutual information. We conclude by suggesting that these techniques have an incredible potential to infer the signature of both resonant and quasi-resonant clusters in fully realised turbulent systems, and yet are also subtle enough to detect qualitative changes in the underlying dynamics between different interacting modes.
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Sami, Kashmir. "Physics of three-dimensional normal shock wave/turbulent boundary layer interactions in rectangular channels." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610179.
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Nielson, Joseph R. "Three Dimensional Characterization of Vocal Fold Fluid Structure Interactions." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3662.
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Voice quality is strongly linked to quality of life; those who suffer from voice disorders are adversely affected in their social, family, and professional relationships. An effort has been made to more fully understand the physics behind how the voice is created, specifically the fluid structure interactions that occur during vocal fold vibration. Many techniques have been developed and implemented to study both the motion of the vocal folds and the airflow that creates the motion. Until recently these techniques have sought to understand a highly three-dimensional phenomenon with 1D or 2D perspectives.This research focuses on the development and implementation of an experimental technique to obtain three-dimensional characterizations of vocal fold motion and fluid flow. Experiments were performed on excised human vocal fold models at the University Hospital Erlangen Medical School in Erlangen, Germany. A novel technique for tracking the motion of the vocal folds using multiple camera viewpoints and limited user interaction was developed. Four high-speed cameras (2000 fps) recorded an excised vocal fold model vibrating at 250 Hz. Based on the images from these four cameras a fully 3D reconstruction of the superior surface of the vocal folds was achieved. The 3D reconstruction of 70 consecutive time steps was assembled to characterize the motion of the vocal folds over eight cycles. The 3D reconstruction accurately modeled the observed behavior of vocal fold vibration with a clearly visible mucosal wave. The average reprojection error for this technique was on par with other contemporary techniques (~20 micrometers). A whole field, time resolved, three-dimensional reconstruction of the vocal fold fluid flow was obtained using synthetic aperture particle image velocimetry. Simultaneous 3D flow fields, subglottal pressure waves, and superior surface motion were presented for 2 consecutive cycles of oscillation. The vocal fold fluid flow and motion measurements correlated with behavior observed in previous three-dimensional studies. A higher resolution view of one full cycle of oscillation was compiled from 16 time resolved data sets via pressure data. The result was a full three-dimensional characterization of the evolution and disintegration of the glottal jet.
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Chpoun, Amer. "Contribution à l'étude d'écoulements hypersoniques (M=5) sur une rampe de compression en configuration 2-D et 3-D." Paris 6, 1988. http://www.theses.fr/1988PA066149.
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Etude expérimentale de l'influence de l'écoulement transversal sur les distributions du flux thermique et de la pression pariétale. Détermination des grandeurs caractéristiques de la zone de décollement. Etude de l'apparition de la transition dans la zone du décollement en fonction du nombre de Reynolds. Solution numérique pour la distribution de pression dans le cas de l'interaction laminaire
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Kim, Sungeun 1963. "Nonlinear interaction of water waves with three-dimensional floating bodies in a current." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/10082.
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Darginavičius, Julius. "Three and four wave parametric interactions for ultrashort pulse generation in the ultraviolet, near and mid-infrared spectral range." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130925_093240-40423.
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In this thesis we investigated and developed three- and four-wave interaction-based frequency conversion methods for ultrashort pulse generation in the ultraviolet (UV), near and mid-infrared (IR) spectral ranges. In particular, efficient generation of Nd:glass laser harmonics was demonstrated experimentally, through noncollinear four-wave difference-frequency mixing in isotropic media. Also, broadband optical parametric amplification in the UV was investigated theoretically and achieved experimentally. The results suggest, that pulses as short as 10 fs could be amplified. We have also developed two methods based on three- and four-wave mixing, that extend the tuning range of a commercial Ti:sapphire laser-NOPA system in the IR. The first method relies on four wave frequency down-conversion, and can achieve up to 20 μJ, sub-30-fs pulses tunable in the 1−1.5 μm range. The second method considers frequency conversion, based on difference frequency generation and optical parametric amplification in BBO crystals. The presented setup delivers two optical-cycle, carrier-envelope phase (CEP)-stable pulses at 2 μm. And finally, we demonstrated supercontinuum generation by filamentation of 20 fs pulses at 2 μm in wide-bandgap solids in the regime of anomalous group velocity dispersion. We also proposed the practical use of intrinsic third harmonic generation, for the CEP stability measurements.<br>Pagrindinis šios disertacijos tikslas – sukurti efektyvius trijų ir keturių bangų sąveikomis paremtus metodus ultratrumpiesiems ultravioletinės (UV), artimosios bei vidurinės infraraudonosios (IR) spektro srities impulsams generuoti. Pademonstruota efektyvi Nd:stiklo lazerio harmonikų generacija nekolinearaus keturbangio skirtuminio dažnio žadinimo metodu izotropinėse terpėse. Disertacijoje taip pat eksperimentiškai ir teoriškai nagrinėjama galimybė stiprinti 10 fs trukmės UV impulsus. Pateikėme du metodus derinamo bangos ilgio IR impulsams generuoti naudojant komercinę Ti:safyro lazerio ir nekolinearaus optinio parametrinio stiprintuvo sistemą. Pirmasis metodas remiasi keturių bangų sąveikomis ir leidžia generuoti 20 μJ energijos, <30 fs trukmės impulsus 1−1.5 μm spektro ruože. Antrojo šaltinio veika remiasi skirtuminio dažnio generacijos bei optinio parametrinio stiprinimo sąveikomis BBO kristaluose. Sukurtas stiprintuvas, generuojantis dviejų optinių ciklų trukmės, stabilios gaubtinės fazės, 2 μm bangos ilgio impulsus ir pademonstruotas jo taikymas itin plataus spektro superkontinuumo generacijai plačios draustinės juostos kietojo kūno terpėse. Galiausiai, ištirta vienalaikė trečiosios harmonikos ir superkontinuumo generacija skaidriose dielektrinėse terpėse, bei pasiūlyta netiesinio f-3f interferometro schema impulso gaubtinės fazes fliuktuacijoms matuoti.
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Christiadi. "Three essays on migration its interaction with regional wage differentials and occupational choice and its application in different discrete choice models /." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4446.
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Schnell, Felizia. "Gaming with sustainability and the life below the waves : How to stimulate a peaceful co-existence with our plante's water and the life there-in through engaging experiences." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-140126.
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In 2015 the UN completed a list of environmental and social goals, one of these goals is the “life in the water” goal, or goal 14. It focuses on the factors endangering the diversity and the ecological balance in the water. However, the goals are formulated with a focus on changes to be done by countries or bigger organisations, not by individuals. This project focused on creating a design for a technical solution that teaches and motivates youths how to help take care of the planet. To do this a design process consisting of a pre-study, concept phase and a workshop were done. The pre-study consisted of interviews, a questionnaire and a pre-study of similar digital games. The interviews focused on how youths and what values and knowledge youths are taught today. These interviews informed a questionnaire that focused on how and what the students were taught about taking care of the oceans. The last part of the pre-study was a review of games with focus on the environment, which was later used to inspire the design process. The concept phase consisted of three iteration phases of concepts and the last phase created the concept tested in the following workshop. Each iteration ended with a discussion of concepts were one or two concepts chosen to focus on. The final concept was a type of exhibition of two digital minigames or simulations and one physical simulation. The three prototypes were linked, in a wizard of Oz type of style, where two of the prototypes, the physical and one of the digital prototype, influenced the environment in the last digital prototype. The collective prototype seemed to inspire engagement and interest from the participants and was mainly received as a good idea. The workshop was held with youths between 12-16 years old and resulted in feedback and a proposition to a redesign.
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Feng, Tsai Kun, and 蔡坤峰. "Three-Dimensional Finite Element Modeling for Wave-Seabed Pipeline Interaction." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/70820677547968899097.
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碩士<br>國立中興大學<br>土木工程學系<br>90<br>The phenomenon of wave-seabed-pipeline interaction has attracted attentions from coastal engineers and marine geotechnical engineers in recent years. However, most previous investigations have been only limited to two-dimensional cases, any directional wave forced on buried pipeline cannot be take account. Furthermore, the boundary between soil buried pipeline assumed perfect bound, which is no match with the actual conditions.
In this study, we will establish a three-dimensional finite element model to investigate the basic mechanism of wave-seabed-pipeline interaction. In the model, the boundary between soil and pipeline will be considered and with the concept of contact mechanics. Based on the new three-dimensional finite element model, Effects of wave characteristics (including water depth, wave height, wave period and wave direction), soil behavior (including quasi-static and dynamic soil behavior) and properties of the pipeline (such as dimensional of pipeline and size of pipeline etc) on the wave-induced soil response will be examined, as well as the stresses within the caisson. All these will provide a guide for engineering practice.
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Chia-LinYeh and 葉佳霖. "Three-dimensional Numerical Simulation of Solitary Wave Interaction with a Submerged Permeable Breakwater." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/19935842626703678207.
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碩士<br>國立成功大學<br>水利及海洋工程學系碩博士班<br>100<br>This study investigates a solitary wave interaction with a submerged permeable structure using three-dimensional numerical solver. The porous structure considered in this paper is twofold. One is considered as an idealized rectangular permeable dike using spatial-averaged concept to derive the macroscopic Navier-Stokes equation for porous media flow coupled with large-eddy-simulation (Hu et al., 2012). The other is to use a series of uniform glass spheres to consist a three-dimensional porous structure.
To validate the present numerical model, the comparisons between simulated results and available experimental data/ analytical solutions in literatures are necessary. We first test solitary wave propagating in a constant water depth, in which the calculated initial wave form and particle trajectories of solitary wave are performed against with Boussiesq theory of solitary wave and measurements by Hsu et al. (2012), respectively. Then numerical tests are carried out to compare with experiments of Yasuda et al. (1997) for solitary wave propatation over semi-infinite breaker step. Finally, numerical experiments are done to compare with results by Lara et al. (2012) for solitary wave over an emerged three-dimensional permeable prism. Generally, the present numerical results show high degree of accuracy, compared to the existing experiments.
Based on the experimental setup for submerged permeable breakwater under solitary wave forcing by Wu et al. (2012a), we conduct two types of porous object, i.e., two-dimensional (2D) spatial-averaged porous media and three-dimensional (3D) real permeable obstacle consisted by uniform glass spheres. The comparisons of the free surface elevation, overall velocity fields as well as cross-section of velocity components are performed between measurements, 2D and 3D numerical simulations. Discussions for the discrepancies between experiments and calculations were given. Moreover, numerical results for the pressure fields and trajectories of marked fluid particles were also discussed.
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Nhi, Vuong Thi Hong, and 王小玫. "Three-Dimensional Numerical Study on the Interaction between Dam-Break Wave and Cylinder Array." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/q5y97n.
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碩士<br>國立中央大學<br>水文與海洋科學研究所<br>106<br>Abstract
The behavior of dam-break bore is very similar to the tsunami bore. Using dam-break wave as a tsunami bore to study its interaction with rigid structures opens a new approach for study tsunami. Fully understanding the physical process of dam-break is crucial for reducing damage and formulating effective disaster prevention and mitigation measures. In this thesis, we study how the energy of a dam-break bore is dissipated by the square cylinders numerically, which present for the coastal vegetation and coastal structures. The computational model, Splash3D, is adopted in this study. Splash3D solves the three-dimensional Navier-Stokes equations directly with Large-Eddy Simulation (LES) as a turbulent closure model. The Volume-of-fluid (VOF) method is used to track the complex free surface. The dam-break flows with two different cylinder array: 0.1 m and 0.2 m in height are numerically investigated. Both velocity magnitude and vorticity are analyzed in upstream as well as downstream region. The results show that the sub-grid scale diffusion is the main reason for energy decline in the dam-break cases due to the domination of turbulent flow. The velocity of the dam-break flows becomes higher when the waves travel downstream. The cylinders’ height affects the wave-breaking and the velocity magnitude as well as vorticity field after the cylinder arrays. The cylinders are taller which causes velocity magnitude downstream smaller. However, the resident time of a high velocity is longer. In addition, the tall-cylinder case has a larger value of velocity magnitude and vorticity near the bottom.
Key words: Tsunami, Dam-break wave, Navier-stokes equations, cylinder array.
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Nimmala, Seshu B. "An efficient high-performance computing based three-dimensional numerical wave basin model for the design of fluid-structure interaction experiments." Thesis, 2010. http://hdl.handle.net/1957/18829.
Full textAbstract:
Fluid-structure interaction (FSI) is an interesting and challenging interdisciplinary area comprised of fields such as engineering- fluids/structures/solids, computational science, and mathematics. FSI has several practical engineering applications such as the design of coastal infrastructure (such as bridges, levees) subjected to harsh environments from natural forces such as tsunamis, storm surges, etc. Development of accurate input conditions to more detailed and complex models involving flexible structures in a fluid domain is an important requirement for the solution of such problems. FSI researchers often employ methods that use results from physical wave basin experiments to assess the wave forces on structures. These experiments, while closer to the physical phenomena, often tend to be time-consuming and expensive. Experiments are also not easily accessible for conducting parametric studies. Alternatively, numerical models
when developed with similar capabilities will complement the experiments very well because of the lower costs and the ability to study phenomena that are not feasible in the laboratory.
This dissertation is aimed at contributing to the solution of a significant component of the FSI problem with respect to engineering applications, covering accurate input to detailed models and a numerical wave basin to complement large-scale laboratory experiments. To this end, this work contains a description of a three-dimensional numerical wave tank (3D-NWT), its enhancements including the piston wavemaker for generation of waves such as solitary, periodic, and focused waves, and validation using large-scale experiments in the 3D wave basin at Oregon State University.
Performing simulations involving fluid dynamics is computational-intensive and the complexity is magnified by the presence of the flexible structure(s) in the fluid domain. The models are also required to take care of large-scale domains such as a wave basin in order to be applicable to practical problems. Therefore, undertaking these efforts requires access to high-performance computing (HPC) platforms and development of parallel codes. With these objectives in mind, parallelization of the 3D-NWT is carried out and discussed in this dissertation.<br>Graduation date: 2011
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Guha, Amitava 1984. "Development of a Computer Program for Three Dimensional Frequency Domain Analysis of Zero Speed First Order Wave Body Interaction." Thesis, 2012. http://hdl.handle.net/1969.1/148193.
Full textAbstract:
Evaluation of motion characteristics of ships and offshore structures at the early stage of design as well as during operation at the site is very important. Strip theory based programs and 3D panel method based programs are the most popular tools used in industry for vessel motion analysis. These programs use different variations of the Green’s function or Rankine sources to formulate the boundary element problem which solves the water wave radiation and diffraction problem in the frequency domain or the time domain.
This study presents the development of a 3D frequency domain Green’s function method in infinite water depth for predicting hydrodynamic coefficients, wave induced forces and motions. The complete theory and its numerical implementation are discussed in detail. An in house application has been developed to verify the numerical implementation and facilitate further development of the program towards higher order methods, inclusion of forward speed effects, finite depth Green function, hydro elasticity, etc. The results were successfully compared and validated with analytical results where available and the industry standard computer program WAMIT v7.04 for simple structures such as floating hemisphere, cylinder and box barge as well as complex structures such as ship, spar and a tension leg platform.
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Mohebbi, Hamid Reza. "Parametric Interaction in Josephson Junction Circuits and Transmission Lines." Thesis, 2011. http://hdl.handle.net/10012/5973.
Full textAbstract:
This research investigates the realization of parametric amplification in superconducting circuits and structures where nonlinearity is provided by Josephson junction (JJ) elements. We aim to develop a systematic analysis over JJ-based devices toward design of novel traveling-wave Josephson parametric amplifiers (TW-JPA). Chapters of this thesis fall into three categories: lumped JPA, superconducting periodic structures and discrete Josephson transmission lines (DJTL).
The unbiased Josephson junction (JJ) is a nonlinear element suitable for parametric amplification through a four-photon process. Two circuit topologies are introduced to capture the unique property of the JJ in order to efficiently mix signal, pump and idler signals for the purpose of signal amplification. Closed-form expressions are derived for gain characteristics, bandwidth determination, noise properties and impedance for this kind of parametric power amplifier. The concept of negative resistance in the gain formulation is observed. A design process is also introduced to find the regimes of operation for gain achievement. Two regimes of operation, oscillation and amplification, are highlighted and distinguished in the result section. Optimization of the circuits to enhance the bandwidth is also carried out.
Moving toward TW-JPA, the second part is devoted to modelling the linear wave propagation in a periodic superconducting structure. We derive closed-form equations for dispersion and s-parameters of infinite and finite periodic structures, respectively. Band gap formation is highlighted and its potential applications in the design of passive filters and resonators are discussed. The superconducting structures are fabricated using YBCO and measured, illustrating a good correlation with the numerical results.
A novel superconducting Transmission Line (TL), which is periodically loaded by Josephson junctions (JJ) and assisted by open stubs, is proposed as a platform to realize a traveling-wave parametric device. Using the TL model, this structure is modeled by a system of nonlinear partial differential equations (PDE) with a driving source and mixed-boundary conditions at the input and output terminals, respectively. This model successfully emulates parametric and nonlinear microwave propagation when long-wave approximation is applicable. The influence of dispersion to sustain three non-degenerate phased-locked waves through the TL is highlighted.
A rigorous and robust Finite Difference Time Domain (FDTD) solver based on the explicit Lax-Wendroff and implicit Crank-Nicolson schemes has been developed to investigate the device responses under various excitations. Linearization of the wave equation, under small-amplitude assumption, dispersion and impedance analysis is performed to explore more aspects of the device for the purpose of efficient design of a traveling-wave parametric amplifier.
Knowing all microwave characteristics and identifying different regimes of operation, which include impedance properties, cut-off propagation, dispersive behaviour and shock-wave formation, we exploit perturbation theory accompanied by the method of multiple scale to derive the three nonlinear coupled amplitude equations to describe the parametric interaction. A graphical technique is suggested to find three waves on the dispersion diagram satisfying the phase-matching conditions. Both cases of perfect phase-matching and slight mismatching are addressed in this work. The incorporation of two numerical techniques, spectral method in space and multistep Adams-Bashforth in time domain, is employed to monitor the unilateral gain, superior stability and bandwidth of this structure. Two types of functionality, mixing and amplification, with their requirements are described. These properties make this structure desirable for applications ranging from superconducting optoelectronics to dispersive readout of superconducting qubits where high sensitivity and ultra-low noise operation is required.
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Mowatt, Sean. "Three dimensional shock wave/boundary layer interactions." Thesis, 2011. http://hdl.handle.net/10539/10680.
Full textAbstract:
An investigation into a three-dimensional, curved shock wave interacting with a three-dimensional,
curved boundary layer on a slender body is presented. Three different nose profiles mounted on a
cylindrical body were tested in a supersonic wind tunnel and numerically simulated by solving the
Navier-Stokes equations. The conical and hemispherical nose profiles tested were found to generate
shock waves of sufficient strength to separate the boundary layer on the cylinder, while the shock
wave generated by the ogival profile did not separate the boundary layer. For the separated flow,
separation was found to occur predominantly on the windward side of the cylinder with the lee-side
remaining shielded from the direct impact of the incident shock wave. A thickening of the boundary
layer on the lee-side of all the profiles was observed. In the conical and hemispherical cases this leads
to the re-formation of the incident shock wave some distance away from the surface of the cylinder. A
complex reflection pattern off the shock wave/boundary layer interaction (SWBLI) was also identified
for the separated flow cases. For comparative purposes an inviscid simulation was performed using
the hemispherical profile. Significant differences between the viscous and inviscid results were noted
including the absence of the boundary layer leading to a simplified shock wave reflection pattern
forming. The behaviour of the incident shock wave on the lee-side of the cylinder was also affected
with the shock wave amalgamating on the surface of the cylinder instead of away from the surface as
per the viscous case. Test data from the wind tunnel identified two separation lines present on the
cylindrical surface of the hemispherical SWBLI generator. The pair of lines were not explicitly
evident in the original CFD simulations run, but were later identified in a high resolution simulation.
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張憲國. "Nonlinear interactions among three-wave trains in finite uniform waterdepth." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/04217153992051897772.
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Hooseria, Shalan Jugdees. "Three-dimensional, curved shock wave interactions with slender bodies at incidence." Thesis, 2015. http://hdl.handle.net/10539/18450.
Full textAbstract:
When two slender bodies are closely spaced within a supersonic freestream, substantial aerodynamic
interference precipitates between the bodies. The bow-shock wave and forebody expansion field
produced by an adjacent body (the disturbance generator) impinge onto the body of interest (the
disturbance receiver), which modifies its surface pressure distribution, effectively altering its nominal
centre of pressure and overall aerodynamic behaviour. The three-dimensional, curved bow-shock
interactions have increased complexity due to the multiple shock reflections, shock wave diffraction
and viscous-shock interactions manifesting with the receiver at incidence in the interference domain.
This research aims to uncover and characterise the underlying flow physics that are generated in the
disturbance flowfield for several multi-slender body configurations.
Parametric wind tunnel investigations were conducted on pairs of slender bodies with ogival,
conical and hemispherical forebody profiles over a wide incidence range. Primary experimental data
was collected using the surface oil flow visualisation technique, where a quantitative data extraction
method was employed to measure the shock impingement location and diffraction path over the
receiving body. Supporting schlieren images of the flowfield were captured through a standard ztype
schlieren system. In addition, time-averaged numerical solutions of the Reynolds-averaged
Navier-Stokes governing equations were conducted using a commercial flow solver. A custom,
gradient-based adaptive mesh refinement algorithm was tailored into the package, providing fine
resolution of the pressure waves in the flowfield. The high-fidelity computational predictions showed
excellent agreement with the experimental data and was used to examine the vortex and shock wave
dynamics produced by the interactions.
A high geometric dependence was observed across all interactions, where the magnitude and
extent of impinging disturbances were bespoke to each configuration, making it challenging to
extract overall trends. However, the interactions could be categorised under three general genres:
The first were the primary windward interactions, where the receivers were negatively pitched
relative to the generator bodies and the impinging disturbances made first contact with the
receivers’ windward surface. The second category had the receiver bodies at positive incidence in
relation to the generators, where impinging disturbances impacted the bodies’ leeward surface
directly, and were designated as primary leeward interactions. The last category assessed the
receiver bodies at angles of sideslip relative to the disturbance generators, where the disturbance
bow-shocks impinged asymmetrically on the receivers. Under each of these categories, the mechanics
of the interactions were observed to be predominantly similar.
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Primary windward interactions: Characteristic to these interactions was the locally elevated
windward surface pressure, which created favourable pressure gradients in the natural crossflow
direction over the bodies. Disturbance shock wave diffraction over the bodies induced significant
effects of compressibility onto the separated flow in the leeward region, producing body-vortices that
were elongated, more elliptic and intensified in comparison to that produced by equivalent
undisturbed bodies. Moreover, the receivers’ body-vortices had a significant influence on the
disturbance shock waves’ transit into the leeward flow region, where the wave was tempered during
passage through the vortices.
Primary leeward interactions: These configurations generated direct shock wave-leeward flow
structure interactions where the inherent low pressure in the receivers’ leeward region attracted the
approaching waves, causing the bow-shocks to bulge out locally towards the bodies. The opposing
natural crossflow over the receivers tempered the disturbance shock waves’ transit into the
windward region, generating complex three-dimensional shock wave geometries around the bodies.
Moreover, the viscous-shock interactions caused severe distortions to the vortical structures disposed
by the receiver bodies.
Interactions with the receiver bodies at angle of sideslip: Additional complexities were generated
by these interactions due to the inherent three-dimensional flow asymmetry, where waves of unequal
strengths diffracted over the windward and leeward surfaces of the receiving bodies. The windward
portion of the diffracted wave caused substantial elevations in surface pressure and an enhanced
crossflow condition over the bodies. The wave that diffracted over the leeward surface interacted
progressively with the receivers’ body-vortices, which caused an imbalance in the strength of the
vortices disposed on either side of the bodies. The strong rotational velocity field of the vortices
influenced the disturbance waves’ transit over the leeward surface substantially, producing complex
compression wave topologies in the receivers’ leeward region.
In general, significant reorganisation of the receivers’ near-surface flow topologies was observed
across all three categories of interactions, the extent of which varied with incidence and the strength
of impinging disturbances. It was also found that the inhomogeneous pressure field introduced by
the disturbance shock waves caused significant modification to the receivers’ incidence-induced
body-vortices. In addition, the inhomogeneous velocity field of the receivers’ body-vortex pair were
observed to affect the disturbance waves’ transit into the bodies’ leeward region. Overall, studying
the slender bodies orientated to produce 3D, curved bow-shock interactions revealed several
fundamental mechanisms and flow physics in the flowfield, with rich phenomena manifesting in the interference domain.
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SIE, YOU-LIANG, and 謝有良. "Three-dimensional Interaction of Dam-break waves and Multi-structures." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/46444q.
Full textAbstract:
碩士<br>國立高雄海洋科技大學<br>海事資訊科技研究所<br>105<br>The purpose of present study aims at the establishment of a numerical model for the solution of Navier-Stokes equations and its application to the interaction of dam-break wave and multi-structures. The control volume finite difference scheme was used to calculate the hydrodynamic performances of dam-break flow through several structures. To overcome the difficulty associated with solving the wave breaking, a volume-of-fluid method was used to track the elevation of free-surface. The present study naturally gives more reasonable results on problems including the partial dam-break flow over three cylinders in tandem arrangements, and interaction between a dam-break surge and three circular cylinders with the consideration of inflow equal to be 10 m3/s. The times variation of force calculation of three cylinders is performed during the interaction of dam-break wave and structures. Finally, the mode is used to the moving objects problem with dam-break flow. These results obtained are demonstrated to the application of the free-surface flows by using the propsed numerical model.
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Jeng-HongKao and 高政宏. "Three-Dimensional Numerical Simulation of Interaction between Waves and Floating Structure with Moorings." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/72387125471619115358.
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博士<br>國立成功大學<br>水利及海洋工程學系<br>103<br>In this study a three-dimensional problem of interactions between waves and a floating structure with moorings is investigated. The problem considered is steady and periodic, and linear wave field, rigid floating structure, and catenary moorings are adopted. For the wave problem the diffracted wave and radiated wave are represented as one induced wave. The wave field is simulated using a boundary element method. The floating structure has six degrees of freedom. The catenary moorings are represented by a finite element model. In the solution the equations of the floating structure and the catenary cable are combined firstly through continuous connections of force and displacement. Then the entire problem is solved using structural equations together with the boundary element wave model. Using the three-dimensional numerical model of wave interaction with a moored floating structure developed in this study, the convergence calculation of numerical mesh is firstly illustrated. In what follows, a floating rectangular cuboid in the channel subjected to incident wave is simulated. The present numerical results are compared with numerical and experimental results by Sannasiraj et al. (1998) to demonstrate accuracy of the present model. Meanwhile the parameters used in three-dimensional simulations in the wave channel to simulate two-dimensional results are also investigated. Finally, the problems of a moored floating rectangular structure in the open sea subjected to incident waves of various directions are investigated. The simulated results include wave fields, structural motions of each degrees of freedom, and mooring forces