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Graaf, Alexandra Johanna van der. "Geese on a green wave: flexible migrants in a changing world." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/291343473.
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Mohd, Haniffah Mohd Ridza. "Wave evolution on gentle slopes : statistical analysis and Green-Naghdi modelling." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:26270be8-c3ee-4749-a290-7bdb4a174a4a.
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An understanding of extreme waves is important in the design and analysis of offshore structures, such as oil and gas platforms. With the increase of interest in the shipping of LNG, the design of import and export terminals in coastal water of slowly varying intermediate depth requires accurate analysis of steep wave shoaling. In this thesis, data from laboratory experiments involving random wave simulations on very gentle slopes have been analysed in terms of a model of large wave events, and the results interpreted by observation of the shape and magnitude of the large wave events. The auto-correlation function of the free surface elevation time histories, called NewWave, has been calculated from the wave spectrum and shown to fit very well up to the point where waves start to break (when compared to the ‘linear’ surface elevation time history). It has been shown that NewWave is an appropriate model for the shape of the ‘linear’ part of large waves provided kd > 0.5. A Stokes-like expansion for NewWave analysis has been demonstrated to match the average shape of the largest waves, accounting for the dominant vertical asymmetry. Furthermore, an appropriate local wave period derived from NewWave has been inserted into a Miche-based limiting criterion, using the linear dispersion equation, to obtain estimates for the limiting wave height. Overall, the analysis confirms the Miche-type criterion applies to limiting wave height for waves passing over very mild bed slopes. A derivation of general Green-Naghdi (GN) theory, which incorporates non-linear terms in its formulation, is also presented. This approach satisfies the boundary conditions exactly and approximates the field equations. The derived 2-dimensional vertical GN Level 1 model, capable of simulating steep waves on varying water depth, is validated against solitary waves and their interactions, and solitary waves on varying water depth and gives good qualitative agreement against the KdV equation. The developed and validated numerical model is used to simulate focussed wave groups on both constant depth and gentle slope. In general, the behaviour of waves simulated by the numerical model is very similar to that observed in the experimental data. There is evidence of vertical asymmetry as the water depth is reduced, owing to the non-linearity. Although the main physics is still controlled by linear dispersion, the higher order harmonics become increasingly important for shoaling waves. The numerical results also show a slope-induced wave set-up that keeps on increasing in amplitude as the wave group travels on the gentle slope.
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Alzahrani, Abdulah. "Local travelling wave solutions and self-similar solutions for a green roof model." Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2776.
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In this thesis we study travelling wave solutions and self-similar solutions for a green roof model and for some simpler models which are derived from that model. We focus on two limiting cases near a dry region and near a saturated region. We start by considering a convection model in the absence of diffusion and sink terms. We show that rarefaction waves and shock solutions exist for several cases. Next, we consider a convection-diffusion model where both the convective and diffusive terms are present and we show that travelling wave solutions and self-similar solutions exist for some cases. Moreover, numerical simulations are used for the travelling wave and self-similar solutions and confirm the analytic predictions. Finally, we consider the green roof model where all terms are present and we show that travelling wave solutions exist, whereas self-similar solutions are not found. We also show the travelling wave solutions exist for the two limiting cases.
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Mosuela, Kristine Angela. "A Parameterized Approach to Estimating Wave Attenuation from Living Shorelines." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/104636.
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Living shorelines and other nature-based solutions have become more widely accepted as a cost-effective, multi-functional, and sustainable approach to coastal resilience. However, in spite of growing stakeholder support, a planning-level understanding of the hydrodynamic impact of living shorelines is not well-developed. Not only do these features vary in size, shape, and structural characteristics, but the wave environment in which they exist can be quiescent or extreme. The work presented in this paper explores the hydrodynamic effects of living shoreline features in such a way that can be generalized across a range of varying physical environments. In a series of Simulation WAves Nearshore (SWAN) simulations, we investigate the effect of wave period, wave height, bed slope, living shoreline feature length in the cross-shore direction, and feature friction coefficient on wave attenuation. Results showed that higher wave period, higher wave height, milder slopes, longer feature lengths, and higher feature roughness largely correlated with higher wave attenuation. However, only on mild slopes did additional feature lengths result in appreciable additional attenuation. Characteristic lengths were thus computed to better illustrate the cost-effectiveness of additional feature lengths given a particular wave environment. These characteristic lengths provide one way to evaluate the hydraulic efficacy of proposed living shoreline projects. In this way, regardless of the particularities of individual project sites, we aim to help planners screen potential living shoreline projects before pursuing more detailed, costly analyses.Master of Science
Living shorelines and other nature-based solutions have become more widely accepted as a cost-effective, multi-functional, and sustainable approach to coastal resilience. However, in spite of growing stakeholder support, a planning-level understanding of the hydrodynamic impact of living shorelines is not well-developed. Not only do these features vary in size, shape, and structural characteristics, but the wave environment in which they exist can be quiescent or extreme. The work presented in this paper explores the hydrodynamic effects of living shoreline features in such a way that can be generalized across a range of varying physical environments. In a series of Simulation WAves Nearshore (SWAN) simulations, we investigate the effect of wave period, wave height, bed slope, living shoreline feature length in the cross-shore direction, and feature friction coefficient on wave attenuation. Results showed that higher wave period, higher wave height, milder slopes, longer feature lengths, and higher feature roughness largely correlated with higher wave attenuation. However, only on mild slopes did additional feature lengths result in appreciable additional attenuation. Characteristic lengths were thus computed to better illustrate the cost-effectiveness of additional feature lengths given a particular wave environment. These characteristic lengths provide one way to evaluate the hydraulic efficacy of proposed living shoreline projects. In this way, regardless of the particularities of individual project sites, we aim to help planners screen potential living shoreline projects before pursuing more detailed, costly analyses.
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Krüger, Jens-Thomas [Verfasser], and Ulrich [Akademischer Betreuer] Brüning. "Green Wave : A Semi Custom Hardware Architecture for Reverse Time Migration / Jens-Thomas Krüger ; Betreuer: Ulrich Brüning." Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/1179785533/34.
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Wong, Chi Fai. "NORTH AMERICAN HEAT WAVE PREDICTABILITY: SKILL ATTRIBUTION AND LAND SURFACE INITIALIZATION IN MEDIUM-RANGE FORECAST MODELS." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2640.
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A developed seamless extreme heat validation approach (Ford et al. 2018) is applied to three Subseasonl Experiment’s (SubX’s) medium-range forecast models, which arethe U.S. National Oceanic and Atmospheric Administration’s Earth System Research Laboratory FIM-iHYCOM (ESRL), the U.S. National Aeronautics and Space Administration’s Earth System Research Laboratory’s Goddard Earth Observing System Atmosphere-Ocean General Circulation Model, Version 5 (GMAO), and the U.S. National Centers for Environmental Prediction’s Global Ensemble Forecast System, version 11 (GEFS), for evaluating their heat wave predictability. Moreover, two land surface initializations, green vegetation fraction (GVF) and heat fluxes (LE/H), of each model are evaluated for understanding the interaction between heat wave predictability and the inconsistencies in the terrestrial segment of land-atmosphere feedbacks. The validation approach shows the overestimated autocorrelation of maximum temperature heat waves causing (1) the lowest reliability and overestimation of heat waves hindcasts, (2) lower heat wave hindcast skill of ensemble mean, and (3) higher discrimination between heat wave hindcast and observations of each ensemble member over lead times for all three models. Both ESRL and GEFS present the relationship between GVF and heat wave hindcast is positive, but negative relationship is shown on the GMAO. In addition, both ESRL and GEFS modelsunderestimate latent heat flux, but overestimate sensible heat flux in the Midwest. Therefore, for both ESRL and GEFS models, the relationship between heat wave and sensible heat fluxes (or GVF) is positive, and negative for the relationship between heat wave and latent heat flux (or evapotranspiration). In contrast, the GMAO model overestimates both latent and sensible heat fluxes in the Midwest. Therefore, for the GMAO model, the relationship between heat wave and latent/sensible heat fluxes (or GVF) is positive, and negative for the relationship between heat wave and evapotranspiration.
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Jalali, Mohammad Reza. "One-dimensional and two-dimensional Green-Naghdi equation solvers for shallow flow over uniform and non-uniform beds." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/23475.
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Numerical simulation of wave behaviour in shallow and deep water is often a key aspect of ocean, coastal, and river hydrodynamic studies. This thesis derives nonlinear one- and two-dimensional level I Green-Naghdi (GN) equations that model the motions of free surface waves in shallow water over non-uniform bed topography. By assuming fitted velocity profiles through the depth, GN equations are simpler than Boussinesq equations, while retaining the wave dispersion property. Implicit matrix solvers are used to solve the spatially discretised 1D and 2D GN equations, with a 4th order Runge Kutta scheme used for time integration. To verify the developed numerical solvers of 1D GN equations, a series of simulations are undertaken for standard benchmark tests including sloshing in a tank and solitary wave propagation over a flat bed. In all cases, grid convergence tests were conducted. In the sloshing test, both numerical schemes and the analytical solution were in complete agreement for small-amplitude free surface motions. At larger values of initial sloshing amplitude, the nonlinear effects caused the free surface waves to steepen, and eventually the numerical simulations became unstable. This could be resolved in future using a shock-capturing scheme. Excellent agreement was achieved between the numerical predictions and analytical solution for solitary waves propagating. The 2D GN equation solver was then verified for the benchmark tests of Gaussian hump sloshing and solitary wave propagation in closed basin. The predicted free surface motions for Gaussian hump sloshing were in good agreement with linear Fourier analytical solutions for a certain initial period, after which nonlinear effects started to dominate the numerical solution. A reversibility check was undertaken. Nonlinear effects were investigated by increasing the amplitude of the hump, and applying harmonic separation (by comparison against slosh predictions for a corresponding Gaussian trough). It was found that the even harmonic components provided a useful indication of the nonlinear behaviour of the 2D GN equations. 2D GN simulations of a 0.6 m amplitude solitary wave propagation in 1 m deep water over a flat, horizontal bed confirmed that nonlinear interaction was correctly modelled, when the solitary wave hit a solid wall and its runup reached 2.36 m which was 0.36m more than the linear analytical solution and almost identical to a second order solution.
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Nagaraj, Mahavir. "Short time scale thermal mechanical shock wave propagation in high performance microelectronic packaging configuration." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/1087.
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The generalized theory of thermoelasticity was employed to characterize the coupled thermal and mechanical wave propagation in high performance microelectronic packages. Application of a Gaussian heat source of spectral profile similar to high performance devices was shown to induce rapid thermal and mechanical transient phenomena. The stresses and temporal gradient of stresses (power density) induced by the thermal and mechanical disturbances were analyzed using the Gabor Wavelet Transform (GWT). The arrival time of frequency components and their magnitude was studied at various locations in the package. Comparison of the results from the classical thermoelasticity theory and generalized theory was also conducted. It was found that the two theories predict vastly different results in the vicinity of the heat source but that the differences diminish within a larger time window. Results from both theories indicate that the rapid thermal-mechanical waves cause high frequency, broadband stress waves to propagate through the package for a very short period of time. The power density associated with these stress waves was found to be of significant magnitude indicating that even though the effect, titled short time scale effect, is short lived, it could have significant impact on package reliability. The high frequency and high power density associated with the stress waves indicate that the probability of sub-micron cracking and/or delamination due to short time scale effect is high. The findings demonstrate that in processes involving rapid thermal transients, there is a non-negligible transient phenomenon worthy of further investigation.
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Ekblom, Olga. "The Green Wave : How communication, advocacy andparticipation measures are included indocuments important for increase bicycling inStockholm City and Nacka Municipality." Thesis, Södertörns högskola, Miljövetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-33313.
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The world is becoming increasingly urban. This puts pressure on a number of functions within cities, not the least the transportation system. Motorized traffic is responsible for a number of negative environmental effects, such as carbon dioxide emissions and particle pollution. To halt this development an increased share of bicyclists is needed. Stockholm County is an area with rapid urbanization. Therefore, a comparative study was undertaken to analyse how Stockholm City and Nacka Municipality are including communication, advocacy and participation measures in documents important for increased bicycling. This as those measures are important to increase the number of bicyclists. The analysis was undertaken by using two typologies, a modified version of the Transtheoretical Model of Change (TTM) to understand how the two cases include communication and advocacy measures whereas Arnstein’s Ladder of Citizens Participation was chosen to understand how participation is included in the documents. The findings suggest many similarities between the two cases but Nacka Municipality perform better with their use of social media, and the activities ”bicycle-friendly workplace” and ”winter bicycling”. From the findings three recommendations where provided: create bicycle councils to improve inclusion of bicyclists in the processes. Second, it is important to have different type of role models across the municipality, both in socio-economic strong and weak areas. And third, create dedicated outlets for bicycle issues, tentatively on a social media outlet. This will increase the status of bicycles, it will promote bicycling as a good transportation choice and it open ups channels for citizens interaction.I dagens allt mer urbaniserade värld börjar fler funktioner i staden sättas under hårt tryck, inte minst transportsektorn. Motordriven trafik är orsaken till en rad negativa miljöeffekter, så som koldioxidutsläpp och partikelföroreningar. För att stävja denna utveckling och öka framkomligheten i de allt mer fullbelagda städerna behöver andelen cyklister öka. Tre områden som är av stort intresse för att öka andelen cyklister är kommunikation, påverkan och delaktighet. Därav undersöktes dessa områden i en jämförande studie. Stockholms län är en region med kraftigt ökande befolkningsandel och där transportsektorn är särskilt ansatt. Därför valdes regionen för att genomföra en jämförande studie där Stockholms stad och Nacka kommun selekterades som studieobjekt. Detta eftersom Stockholms stad är den störta kommunen i regionen, de är många som arbetar i de centrala delarna och de finns ökande framkomlighetsproblem i kommunen. Därefter valdes Nacka kommun som jämförande kommun, baserat på differensmetoden. Stockholms stad och Nacka kommun har liknande socio-ekonomisk sammansättning och de har liknande förutsättningar vad gäller cykelmöjligheter. Utöver det har båda kommunerna egna cykelstrategier. De som skiljer kommunerna åt är att Nacka kommun under senare år har blivit prisat för sitt arbete inom cykelområdet. De tilldelades 2016 Årets Cykelprestation av Stockholms regionala cykelkansli under 2017 placerade sig Nacka kommun som nummer ett för medelstora kommuner, och fyra totalt, i Kommunvelometern presenterat av Cykelfrämjandet. I Kommunvelometern hamnar Stockholm Stad som 8 av 11 stora kommuner och på plats 16 totalt. Undersökningen gjordes genom analys av dokument som ansågs ha betydelse för cykelsatsningar inom respektive kommun. Det innefattade bland annat översiktsplaner, framkomlighetsstrategier och interna kommunikationsdokument. Analysen gjordes med hjälp av två typologier. För att se hur kommunikation och påverkan används i dokumenten användes en utveckling av typologin Transtheoretical Model of Change (TTM) och för att se hur delaktighets beskrevs i dokumenten användes Arnsteins delaktighetsstege. Analysen visade många likheter mellan fallen. Dock framgick det att Nacka kommun presterade bättre med sin användning av sociala medier och genom främst två aktiviteter, Cykelvänlig arbetsplats och Cykla på vintern. Från slutsatsen kunde sedan tre rekommendationer lämnas. För det första bör cyklister inkluderas tidigt i processerna genom någon from av cykelråd. Det är också viktigt att försöka skapa cykelförebilder runtom i hela kommunerna, både i socio-ekonomiska starka och svaga områden. Till sist bör cykeldedikerade kommunikationskanaler skapas, förslagsvis på sociala medier. Detta ger en plattform som ger cykling ökad status, där cykling kan främjas och det skapar inte minst en möjlighet för medborgarkommunikation.
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Abdolmaleki, Kourosh. "Modelling of wave impact on offshore structures." University of Western Australia. School of Mechanical Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0055.
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[Truncated abstract] The hydrodynamics of wave impact on offshore structures is not well understood. Wave impacts often involve large deformations of water free-surface. Therefore, a wave impact problem is usually combined with a free-surface problem. The complexity is expanded when the body exposed to a wave impact is allowed to move. The nonlinear interactions between a moving body and fluid is a complicated process that has been a dilemma in the engineering design of offshore and coastal structures for a long time. This thesis used experimental and numerical means to develop further understanding of the wave impact problems as well as to create a numerical tool suitable for simulation of such problems. The study included the consideration of moving boundaries in order to include the coupled interactions of the body and fluid. The thesis is organized into two experimental and numerical parts. There is a lack of benchmarking experimental data for studying fluid-structure interactions with moving boundaries. In the experimental part of this research, novel experiments were, therefore, designed and performed that were useful for validation of the numerical developments. By considering a dynamical system with only one degree of freedom, the complexity of the experiments performed was minimal. The setup included a plate that was attached to the bottom of a flume via a hinge and tethered by two springs from the top one at each side. The experiments modelled fluid-structure interactions in three subsets. The first subset studied a highly nonlinear decay test, which resembled a harsh wave impact (or slam) incident. The second subset included waves overtopping on the vertically restrained plate. In the third subset, the plate was free to oscillate and was excited by the same waves. The wave overtopping the plate resembled the physics of the green water on fixed and moving structures. An analytical solution based on linear potential theory was provided for comparison with experimental results. ... In simulation of the nonlinear decay test, the SPH results captured the frequency variation in plate oscillations, which indicated that the radiation forces (added mass and damping forces) were calculated satisfactorily. In simulation of the nonlinear waves, the waves progressed in the flume similar to the physical experiments and the total energy of the system was conserved with an error of 0.025% of the total initial energy. The wave-plate interactions were successfully modelled by SPH. The simulations included wave run-up and shipping of water for fixed and oscillating plate cases. The effects of the plate oscillations on the flow regime are also discussed in detail. The combination of experimental and numerical investigation provided further understanding of wave impact problems. The novel design of the experiments extended the study to moving boundaries in small scale. The use of SPH eliminated the difficulties of dealing with free-surface problems so that the focus of study could be placed on the impact forces on fixed and moving bodies.
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Boutin, Claude. "Dynamique des milieux poreux saturés déformables : fonctions de Green, perméamètre dynamique." Grenoble 1, 1987. http://www.theses.fr/1987GRE10026.
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Borghetti, Beatrice. "Sistemi RFID per applicazioni ciclistiche." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/12996/.
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In questo lavoro di tesi è stato realizzato e caratterizzato un sistema RFID che permette di rilevare e stimare la velocità di passaggio di biciclette lungo un percorso in cui si intende creare una "Green Wave", ovvero una corsia dedicata ai ciclisti che permette a chi la percorre di trovare sempre semafori verdi. Questa tesi affronta tematiche ispirate al progetto europeo XCYCLE volto a potenziare la sicurezza dei ciclisti.
Un sistema RFID è formato da un ricetrasmettitore (Reader) in grado di interrogare e rilevare trasponder a radiofrequenza di piccole dimensioni (Tag), e da un sistema informativo collegato al Reader che permette di gestire i dati contenuti nei Tag (Client).
Nel caso di questa specifica applicazione si è scelto di utilizzare due antenne collegate al Reader, poste ad una data distanza lungo la pista ciclabile, e si sono posizionati i Tag sulle biciclette che la percorrono con lo scopo di rilevare le loro direzioni e velocità.
Il Client comunica con il Reader tramite il protocollo standard LLRP; è stato quindi creato un software apposito che si occupa, tramite scambio di pacchetti LLRP, di stabilire una connessione con il Reader e interrogarlo per conoscere informazioni sui Tag rilevati, come ad esempio l'identificativo, l'istante di lettura e la potenza con cui si è ricevuto il segnale.
Si sono svolte attività sperimentali per stabilire le performance del sistema in termini di accuratezza nella stima della velocità: sono stati collocati su una bicicletta più Tag di vario tipo e in posizioni diverse, sono state disposte le antenne lungo la pista riservata al transito delle biciclette e, usando il software creato, si sono registrati i dati mentre la bicicletta veniva guidata nel tratto di strada.
Infine sono stati testati e valutati diversi algoritmi che, in base a questi dati raccolti, stimano la velocità di percorrenza di ogni Tag e quindi della bicicletta su cui sono stati applicati.
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Jörneskog, Gustav, and Josef Kandelan. "Using Deep Reinforcement Learning For Adaptive Traffic Control in Four-Way Intersections." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-158204.
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The consequences of traffic congestion include increased travel time, fuel consumption, and the number of crashes. Studies suggest that most traffic delays are due to nonrecurring traffic congestion. Adaptive traffic control using real-time data is effective in dealing with nonrecurring traffic congestion. Many adaptive traffic control algorithms used today are deterministic and prone to human error and limitation. Reinforcement learning allows the development of an optimal traffic control policy in an unsupervised manner. We have implemented a reinforcement learning algorithm that only requires information about the number of vehicles and the mean speed of each incoming road to streamline traffic in a four-way intersection. The reinforcement learning algorithm is evaluated against a deterministic algorithm and a fixed-time control schedule. Furthermore, it was tested whether reinforcement learning can be trained to prioritize emergency vehicles while maintaining good traffic flow. The reinforcement learning algorithm obtains a lower average time in the system than the deterministic algorithm in eight out of nine experiments. Moreover, the reinforcement learning algorithm achieves a lower average time in the system than the fixed-time schedule in all experiments. At best, the reinforcement learning algorithm performs 13% better than the deterministic algorithm and 39% better than the fixed-time schedule. Moreover, the reinforcement learning algorithm could prioritize emergency vehicles while maintaining good traffic flow.
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Trlica, Ondřej. "Vliv fázové přeměny vody v zemině na průběh teplotního kmitu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265588.
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This thesis deals with the study of soils freezing in terms of phase change of water contained in the soil strata on green roofs. The aim of this work is to verify the effect of phase transformation of water on the course of temperature oscillation. First described the basic characteristics of soils generally, and subsequently described processes occurring during phase transformation of water in the soil and has been carried out experimental verification of the effect of moisture in the soil on the course of temperature oscillation. In the overall evaluation of the work, an analysis of the effect of phase change water in soil on the course of temperature oscillation and the resulting conclusion of work.
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Clerc, Vincent. "Caractérisation de milieux multiplement diffusants à l'aide de corrélations dans la coda." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAU011/document.
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Les signaux enregistrés à la surface du globe sont composés de trois types d'ondes : des ondes directes, des ondes réfléchies plus ou moins facilement interprétables, et des ondes multiplement diffusées beaucoup plus complexes à interpréter. Certaines propriétés physiques de ces ondes multiplement diffusées permettent de les assimiler au bruit sismique ambiant. Nous appliquons des techniques de corrélation de bruit sismique développées ces dernières années à la coda sismique, afin de tirer des informations sur le caractère multiplement diffusant du milieu. En particulier, nous montrons que le théorème reliant fonction de Green et champ ambiant peut être utilisé dans la coda. La dynamique temporelle de la reconstruction de la fonction de Green est alors un indicateur de la répartition de l'énergie dans le milieu. En reconstruisant la fonction de Green à l'aide de corrélations pour plusieurs fenêtres de temps dans la coda, nous montrons qu'il est possible de relier la symétrie des parties causales et acausales de la fonction de Green au libre parcours moyen du milieu. Nous développons ensuite des simulations numériques de propagation d'onde acoustique en 2D. Nous observons que l'évolution de la reconstruction des fonctions de Green observée dans ce milieu et celle prédite par la théorie est proche. La même approche est ensuite appliquée à des données sismologiques de terrain, sans permettre de retrouver la même dynamique. Nous développons alors une méthode de type MCMC permettant de reconstruire les fonctions de Green du milieu de manière optimaleMost of the waves recorded by seismometers are hard to interpret because of the complexity of the propagation medium, especially the late part of the seismic coda. These multiply scattered coda waves are close in nature to the ambient noise. We are applying recent noise correlation techniques to coda waves in order to retrieve information about the scattering medium. We show how the relationship between ambient noise and Green's function can be used in the case of the seismic coda. The quality of the Greens function retrieved by cross correlation of time windows in the coda is a proxy indicating the energy partition in the propagation medium. In particular, we establish a link between the symmetry of the causal and acausal parts of the reconstructed Green's function and the mean free path. We validate this theoretical approach with acoustical 2D numerical simulations. The same approach seems inefficient on a seismological dataset, due to the high S/N ratio and the non optimal repartition of receivers. Hence, we develop an MCMC based algorithm in order to optimally reconstruct the green's function in the seismic coda
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Frendo, Molly Elizabeth. "GENERATIONAL FEMINISM AND ACTIVISM: USING BGSU AS A CASE STUDY." Connect to this title online, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1150228848.
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Bezerra, Cardoso Maurício Henrique. "Modélisation de la propagation des ondes électromagnétiques près du sol : application aux réseaux sans fil." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1035/document.
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Motivée par le développement de diverses applications déployant des antennes près d'une interface, comme les systèmes militaires UGS, les réseaux corporels sans fil BAN et la surveillance environnementale impliquant des capteurs au sol, cette thèse porte sur la modélisation de la propagation des ondes électromagnétiques près d'une interface. Tout d'abord, la méthode classique de l'optique géométrique est confrontée à des formules approchées fournies par Norton et par Bannister. Cette étude met en évidence les cas où l'optique géométrique ne décrit pas correctement la propagation près de la surface. Pour une compréhension plus exhaustive, les fonctions de Green de ce type de propagation, présentées sous forme d'intégrales de Sommerfeld, sont évaluées à la lumière de la méthode de la plus grande pente. Cette évaluation permet d'extraire trois équations importantes pour la propagation près d'une interface. La première est la condition essentielle pour que la proximité au sol puisse profiter au bilan de liaison grâce à l'excitation d'une composante de l'onde diffractée qui se propage près de l'interface. Les deux autres identifient des distances critiques qui bornent le début et la fin de la zone présentant un affaiblissement de trajet amélioré. L'ensemble de ces trois équations permet d'évaluer le rôle de certains paramètres physiques, notamment les propriétés électromagnétiques du sol, la fréquence de travail et la hauteur des antennes. Cette thèse inclut également les pistes pratiques envisagées pour une démonstration de faisabilité de l'amélioration d'une liaison sans fil par la proximité des antennes à l'interface. La couverture du sol ayant une importance prépondérante, nous présentons des recherches préliminaires sur la réalisation et la caractérisation d'un matériau approprié pour ce type de propagation. Dans un axe de recherche parallèle, cette thèse évalue également l'exactitude et la pertinence d'une nouvelle formulation théorique pour la propagation près du sol. Cette formulation dite « de Schelkunoff » suscite des controverses dans la communauté scientifiqueMotivated by the development of various applications deploying antennas near an interface, such as military systems (UGS), wireless body area networks (BAN) and environmental monitoring involving ground sensors, this thesis deals with the near-ground wave propagation modelling. First, the results of the geometrical optics are confronted with the approximations provided by Norton and Bannister. This study reveals the cases where geometrical optics does not correctly describe the wave propagation near the surface. For a more comprehensive understanding, Green's functions of this type of propagation, presented as Sommerfeld integrals, are evaluated using the steepest descent technique. This evaluation offers the possibility to extract three important equations for near-ground wave propagation. The first one presents the essential condition under which the link budget can benefit from the ground proximity through the excitation of a diffracted wave component propagating near the interface. The other two equations identify critical distances indicating the beginning and the end of the zone with an improved path loss. All these three equations highlight the role of certain physical parameters, in particular the electromagnetic properties of the ground, the working frequency and the heights of the antennas. This thesis also includes the practical solutions that can be considered to demonstrate the feasibility of improving a wireless link by the proximity of the antennas to the interface. Since floor coating is of major importance, we present preliminary research on the realisation and characterisation of a suitable material for this type of propagation. In a parallel research axis, this thesis also evaluates the accuracy and relevance of a new theoretical formulation for near-ground propagation. The "so-called Schelkunoff" formulation has become a controversial issue in the scientific community
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Garcia, Rosmond. "Contribution à l'étude de circuits planaires par une méthode itérative basée sur le concept d'onde (F. W. C. I. P)." Toulouse, INPT, 2001. http://www.theses.fr/2001INPT046H.
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Le travail présenté dans ce mémoire, a été dans un premier temps de formuler une nouvelle méthode itérative basée sur le concept d'onde (la FWCIP) pour modéliser tout type de dispositifs micro-ondes planaires sans aucune contrainte géométrique, puis à l'améliorer au fur et à mesure que les difficultés sont survenues. L'objectif de cette méthode est de déterminer une relation simple et efficace permettant de mettre en relation les ondes incidentes et réfléchies dans les différents milieux environnant la discontinuité en exprimant la réflexion dans le domaine modal et la diffraction, définie à partir des conditions aux limites et de continuité, dans le domaine spatial. Le processus itératif s'appuie sur la transformée de Fourier rapide en modes (FFTM) pour passer rapidement d'un domaine à l'autre et pour s'affranchir des fonctions d'essai. En sus, la FFTM permet de diminuer considérablement le temps de calcul. L'algorithme de la moyenne mobile a été appliqué à la méthode afin d'accroître les performances de celle-ci, en permettant l'accélération de la convergence de l'impédance vue par la source. Ce simulateur, après quelques comparaisons avec la littérature, se prête aussi bien à l'étude de structures en guide d'ondes classique (iris), des structures microrubans (antennes, coupleurs), qu'à des dispositifs coplanaires (filtres) en simple ou multicouches. Ensuite, la formulation de la méthode a été révisée pour permettre l'analyse de structures imprimées sur des matériaux artificiels réalisés soit à partir de plots métalliques (via-holes) disposés périodiquement dans le substrat diélectrique d'un circuit microruban ou à partir de gravures périodiques dans le plan de masse d'une ligne microruban. La FWCIP combinée avec la méthode des éléments de frontière a permis de définir les principales caractéristiques des filtres à gap photonique. Pour terminer, une étude comparative a été faite entre la simulation et les mesures.
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Campomanes, Campomanes Alfredo Jorge, and Olivera Joel Moisés López. "Reducción de la congestión vehicular a través de la implementación de la Ola Verde en la Av. Caminos del Inca en el tramo comprendido entre Jr. Batallón Callao Norte y Jr. Cádiz en el distrito de Surco." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/626381.
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El congestionamiento vehicular es uno de los problemas que más se agudiza en la ciudad de Lima. Este problema se ve reflejada en casi todas las calles y avenidas principales de la ciudad, debido a factores como el incremento del parque automotor que hacen colapsar la capacidad de la infraestructura y dejan en desuso la gestión de tránsito para la que fue diseñada; dicho de otra manera, el incremento del flujo vehicular ocasiona gran congestión, largas colas, prolongadas demoras y niveles de servicio deficientes. La zona de estudio a tratar se encuentra en el distrito de Surco y la vía intervenida es la avenida Caminos del Inca en el tramo del jirón Batallón Callao hasta el jirón Cádiz atravesando avenidas importantes como Velazco Astete e Higuereta. Esta avenida es una de las más transitadas del distrito de Surco a causa de los centros comerciales, institutos, universidades, entre otros, que se encuentran cercanas a esta importante arteria vial.
Por ello, este trabajo de tesis tiene como objetivo principal disminuir la congestión vehicular de la Av. Caminos del Inca en el tramo de estudio y mejorar los niveles de servicio en sus intersecciones con la implementación de la ola verde a través del modelamiento y simulación en el software Synchro 8.
Para la elaboración de este trabajo se recopilaron datos de campo como el aforo vehicular para determinar la hora punta y el volumen horario de máxima demanda vehicular, asimismo se realizó la medición de los ciclos semafóricos y sus faces en un día típico de la semana. Con todos estos datos compilados en el trabajo de campo, se obtuvieron los grados de saturación y los niveles de servicio actuales para que posteriormente sean evaluadas a fin de implementar la ola verde y optimizar el tránsito.
Finalmente, con la implementación de la ola verde y las modificaciones de gestión de tráfico se obtuvieron mejoras notables como optimización de los niveles de servicio en las intersecciones, por ejemplo, en la intersección N° 01 pasó de C a B, en la N° 02 de F a D, en la N° 03 de C a B y en la N° 04 de C a B; asimismo, las esperas en las intersecciones disminuyeron favorablemente como se indica a continuación, en la intersección N° 01 Bajó de 20.1s a 16.7s, en la N° 02 de 332.2s a 35.3s, en la N° 03 de 239.9s a 11.4s y en la N° 04 de 37.0s a 6.3s; de igual forma, el tiempo de recorrido de un punto extremo, intersección N° 01, al otro, Intersección N° 04, mejoró considerablemente de 6 minutos y 30 segundos aproximadamente a 1 minuto y 28 |segundos debido a la sincronización progresiva del color verde de los semáforos en cada intersección.Traffic congestion is one of the most acute problems in the city of Lima. This problem is reflected in almost all the streets and main avenues of the city, due to factors such as the increase in the vehicle fleet that collapses the capacity of the road infrastructure and leaves the traffic management for which it was designed in disuse; In other words, the increase in the flow of vehicles causes great congestion, long queues of vehicles, prolonged delays and poor service levels. The study area to be treated is in the district of Surco and the intervened road is the Caminos del Inca avenue in the stretch from Batallón Callao street to Cádiz street crossing important avenues such as Velazco Astete and Higuereta. This is one of most heavily traveled avenue in the district of Surco because of the shopping centers, institutes, universities, among others, that are close to this important traffic artery. Therefore, this thesis work has as main objective to reduce the vehicular congestion of this avenue and improve the service levels of its intersections with the implementation of the green wave through modeling and simulation in the Synchro 8 software. For the elaboration of this research work, field data were collected, such as the vehicle capacity to determine the peak hour and the hourly volume of maximum vehicular demand, as well as the measurement of the traffic light cycles and their faces in a typical day of the week. With all this data compiled in the field work, saturation degrees and current service levels were obtained so that later they can be evaluated in order to implement the green wave and optimize traffic. Finally, with the implementation of the green wave and traffic management modifications, notable improvements were obtained such as optimization of service levels at intersections, for example, at intersection No. 01 it went from C to B, at No. 02 from F to D, in No. 03 from C to B and in No. 04 from C to B; in the same way, the travel time from an extreme point, intersection No. 01, to the other, Intersection No. 04, improved considerably from 6 minutes and 30 seconds approximately to 1 minute and 28 seconds due to the progressive synchronization of the green colour of the traffic lights in each intersection.
Tesis
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Koabaz, Mahmoud. "Contribution à l’étude des ondes de LAMB dans une plaque anisotrope : théorie et expérience." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14071/document.
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Le rayonnement d'une source ultrasonore située sur l'une des interfaces d'une plaque anisotrope est étudié. Le calcul du tenseur de Green est effectué dans le cas général d'un problème 3D. Une décomposition en multiples réflexions /réfractions, constituant une série de rayons au sein de la plaque, est utilisée pour une comparaison théorie-expérience dans le cas d'un mono cristal de Cuivre. La vitesse de phase et la vitesse d'énergie sont mesurées en fonction de la fréquence ou de la direction d'observation, pour une plaque de carbone-époxy unidirectionnels, et comparées avec la théorieThe ultrasonic radiation from a source located on one of the interfaces of an anisotropic plateis studied. The calculation of the Green tensor is performed in the general case of a 3Dproblem. Decomposition into multiple reflections /refractions, as a series of rays in the plate,is used for comparison between theory and experiment in the case of a single crystal of copper. The phase velocity and energy velocity are measured in terms of frequency ordirection of observation, for a plate of unidirectional carbon-epoxy, and compared withtheory
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Chen, Li-Jen. "Bernstein-Greene-Kruskal electron solitary waves in collisionless plasmas /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/9644.
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Carvalho, Paulo Gustavo Serafim de [UNESP]. "Equação reduzida para ondas curtas na superfície da água." Universidade Estadual Paulista (UNESP), 2003. http://hdl.handle.net/11449/91861.
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carvalho_pgs_me_ift.pdf: 273148 bytes, checksum: b8f03ddb09e18a5f045875f4ec5b3d33 (MD5)Estuda-se o comportamento de ondas de superfície em um fluido invícido no limite de curtos comprimentos de onda e levando em conta efeitos não-lineares. Uma equação para este limite é obtida e algumas soluções são exibidas.
Abstracts: The behaviour of surface-waves on a inviscid fluid is studied in the short-wave limit, taking nonlinear effects into account. An equation describing this limit is obtained and some of its solutions exibited.
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Alzawad, Ahmed. "Bedrock Fracture Zone Delineation Using Multichannel Analysis of Surface Waves in Carter Park, Bowling Green, Ohio." Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1338837442.
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Alevizaki, Athina. "Analysis and control of elastic waves in phononic structures of poroelastic inclusions in a fluid." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMLH24/document.
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Dans le présent document de thèse, une extension de la méthode de calcul de la diffusion multiple stratifiée est développée en y incluant des structures phononiques à base de diffuseurs sphériques poroélastiques saturés immergés dans un fluide, en combinant la théorie de Biot avec le formalisme de diffusion multiple. La méthode est alors appliquée à une étude théorique, bien au-delà de l’approximation à grandes longueurs d’onde d’un milieu effectif, de la réponse acoustique d’un milieu granulaire à double porosité saturé, formé d’un réseau cristallin compact de sphères poreuses rigides ou molles. On montre que la variation de la taille des pores et/ou celle de la porosité dans une gamme allant du millimètre au micromètre pour le diamètre des sphères altère d’une façon significative les spectres de transmission, réflexion, et d’absorption d’une couche plane d’épaisseur finie de ces matériaux. Les spectres présentés sont analysés par référence aux modes acoustiques de sphères poreuses isolées d’une part, puis par rapport aux diagrammes de dispersion des cristaux infinis correspondants. Une interprétation cohérente de la physique sous-jacente est donnée. Ces résultats mettent en évidence l’occurrence de nouveaux modes, localisés dans la sphère, provenant des ondes longitudinales lentes propres aux milieux poroélastiques. Ces modes induisent quelques caractéristiques remarquables dans le comportement acoustique de ces matériaux à double porosité, comme des bandes d’absorption non-dispersive larges ou étroites en fréquence et/ou des bandes d’arrêt directionnel. Les propriétés acoustiques de ces structures phononiques à l’échelle sub-micrométrique, i.e. en régime hypersonique (GHz), peuvent être évaluées expérimentalement par diffusion Brillouin. Dans ce document, une approche théorique élasto-optique rigoureuse, basée sur les fonctions de Green, est proposée afin de décrire la diffusion inélastique de la lumière due aux variations spatiotemporelles de l’indice de réfraction du matériau induites par des phonons. Dans ce cadre des expressions analytiques de l’intensité d’un faisceau de lumière diffusé par une particule sphérique dans le vide sont dérivées, permettant ainsi d’améliorer la précision et rapidité des calculs précédents. Les grandes lignes de ce développement théorique jettent les bases pour une description rigoureuse de cet effet dans le cas de cristaux phononiques composés de particules sphériques colloïdalesIn the present thesis, an extension of the layer multiple scattering computational methodology to phononic structures of fluid-saturated poroelastic spherical bodies, combining Biot's theory with multiple scattering techniques, is developed. The method is applied to the theoretical study, beyond the long wavelength effective-medium approximation, of the acoustic response of double-porosity liquid-saturated granular materials consisting of close-packed hard or soft porous spheres. It is shown that variations of the pore size and/or the porosity within the millimeter and submillimeter-sized spherical grains signicantly alters the transmission, reflection, and absorption spectra of finite slabs of these materials. The calculated spectra are analyzed by reference to the acoustic modes of the constituent porous spherical grains as well as to relevant dispersion diagrams of correspondingly infinite crystals, and a consistent interpretation of the underlying physics is presented. Our results provide evidence for the occurrence of novel, unprecedented modes, localized in the sphere, which arise from slow longitudinal waves that are peculiar to poroelastic media. These modes induce some remarkable features in the acoustic behavior of these double-porosity materials under study, such as broad or narrow dispersionless absorption bands and/or directional transmission gaps. The acoustic properties of phononic (sub)micro structures, in the hypersonic (GHz) regime, can be probed, in general, by Brillouin light scattering experiments. In the present thesis we undertake a rigorous full elasto-optic theoretical approach to inelastic light scattering due to phonon induced spatiotemporal variations of the refractive index of a medium, based on Green's functions, and derive analytical expressions for the intensities of the scattered light beams by single spherical particles in vacuum, thus improving the computational efficiency and accuracy of previous calculations. The above framework provides, also, the basis for a rigorous description of the effect for phononic crystals of colloidal spherical particles
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Rice, Tamara J. "Riding out the waves community college transfers graduating with bachelor's degrees /." Bowling Green, Ohio : Bowling Green State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1206385493.
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Filippini, Andrea Gilberto. "Free surface flow simulation in estuarine and coastal environments : numerical development and application on unstructured meshes." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0404/document.
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Over the last decades, there has been considerable attention in the accurate mathematical modeling and numerical simulations of free surface wave propagation in near-shore environments. A physical correct description of the large scale phenomena, which take place in the shallow water region, must account for strong nonlinear and dispersive effects, along with the interaction with complex topographies. First, a study on the behavior in nonlinear regime of different Boussinesq-type models is proposed, showing the advantage of using fully-nonlinear models with respect to weakly-nonlinear and weakly dispersive models (commonly employed). Secondly, a new flexible strategy for solving the fully-nonlinear and weakly-dispersive Green-Naghdi equations is presented, which allows to enhance an existing shallow water code by simply adding an algebraic term to the momentum balance and is particularly adapted for the use of hybrid techniques for wave breaking. Moreover, the first discretization of the Green-Naghdi equations on unstructured meshes is proposed via hybrid finite volume/ finite element schemes. Finally, the models and the methods developed in the thesis are deployed to study the physical problem of bore formation in convergent alluvial estuary, providing the first characterization of natural estuaries in terms of bore inceptionCes dernières décennies, une attention particulière a été portée sur la modélisation mathématique et la simulation numérique de la propagation de vagues en environnements côtiers. Une description physiquement correcte des phénomènes à grande échelle, qui apparaissent dans les régions d'eau peu profonde, doit prendre en compte de forts effets non-linéaires et dispersifs, ainsi que l'interaction avec des bathymétries complexes. Dans un premier temps, une étude du comportement en régime non linéaire de différents modèles de type Boussinesq est proposée, démontrant l'avantage d'utiliser des modèles fortement non-linéaires par rapport à des modèles faiblement non-linéaires et faiblement dispersifs (couramment utilisés). Ensuite, une nouvelle approche flexible pour résoudre les équations fortement non-linéaires et faiblement dispersives de Green-Naghdi est présentée. Cette stratégie permet d'améliorer un code "shallow water" existant par le simple ajout d'un terme algébrique dans l'équation du moment et est particulièrement adapté à l'utilisation de techniques hybrides pour le déferlement des vagues. De plus, la première discrétisation des équations de Green-Naghdi sur maillage non structuré est proposée via des schémas hybrides Volume Fini/Élément Fini. Finalement, les modèles et méthodes développés dans la thèse sont appliqués à l'étude du problème physique de la formation du mascaret dans des estuaires convergents et alluviaux. Cela a amené à la première caractérisation d'estuaire naturel en terme d'apparition de mascaret
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Ioannou-Giannakis, Christos. "Collective bargaining, incomes policy and relative wage flexibility in Greek manufacturing, 1966-1988." Thesis, London School of Economics and Political Science (University of London), 1990. http://etheses.lse.ac.uk/1196/.
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Based on the assumption that industrial relations influence labour market outcomes, the thesis examines first, the characteristics and the evolution of bargaining structures and procedures in the Greek system of industrial relations, second, the governmental policies aimed at wage and employment regulation, and third, the extent to which, in the context of developments in industrial relations as well as in the context of incomes policy, there was room for relative wage flexibility in the Greek manufacturing sector. The main conclusion of the thesis is that, despite the extensive and continuous regulation of wage determination procedures by successive governments, changes in industrial relations which occurred after 1975 and were marked by decentralised, fragmented and informal collective bargaining, were accompanied by flexibility in relative wages. The sources of this flexibility, which is largely noncompetitive, are related to industry-specific productivity gains as well as to industry-specific rates of strike activity. Moreover, the rise of decentralised, fragmented and informal collective bargaining influenced the effectiveness of the norm-based and the indexation incomes policies as far as variation in the inter-industry wage structure in the Greek manufacturing sector is concerned.
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Harwood, Adrian Roy George. "Numerical evaluation of acoustic Green's functions." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/numerical-evaluation-of-acoustic-greens-functions(809386ea-59cb-453b-9770-5e3250b35e98).html.
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The reduction of noise generated by new and existing engineering products is of increasing importance commercially, socially and environmentally. Commercially, the noise emission of vehicles, such as cars and aircraft, may often be considered a selling point and the effects of noise pollution on human health and the environment has led to legislation restricting the noise emissions of many engineering products. Noise prediction schemes are important tools to help us understand and develop a means of controlling noise. Acoustic problems present numerous challenges to traditional CFD-type numerical methods rendering all but the most trivial problems unsuitable. Difficulties relate to the length scale discrepancies which arise due to the relatively tiny pressure and density fluctuations of an acoustic wave propagating over large distancesto the point of interest; the result being large computational domains to capture wave behaviour accurately between source and observer. Noise prediction may be performed using a hybrid Computational Aero-Acoustics (CAA) scheme, an approach to noise prediction which alleviates many issues associated with exclusively numerical or analytical approaches. Hybrid schemes often rely on knowledge of a Green’s function, representing the scattering of the geometry, to propagate source fluctuations to the far-field. Presently, these functions only exist in analytical form for relatively simple geometries. This research develops principles for the robust calculation of Green’s functions for general situations. In order to achieve this, three techniques to computeGreen’s functions for the Helmholtz equation within an extended class of 2D geometries are developed, evaluated and compared. Where appropriate, their extension to 3D is described. Guidance is provided on the selection of a suitable numerical method in practice given knowledge of the geometry of interest. Through inclusion of the numerical methods for the construction of Green’s functions presented here, the applicability of existing hybrid schemes will be significantly extended. Thus, it is expected that noise predictions may be performed on a more general range of geometries while exploiting the computational efficiency of hybrid prediction schemes.
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Walker, Lauren L. "Boiotian black figure floral ware : a re-analysis of the Southern style with an introduction to floral groups from Halíartos." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85212.
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Black Figure Floral Ware is an understudied style of pottery which was produced in Boiotia and the nearby regions of Euboia and Phokis during the fifth and fourth centuries B.C.E. Floral Style vases are painted with compositions formed predominantly of palmettes and lotuses rendered in black gloss without the incised details which are typically associated with Black Figure pottery. The corpus of Boiotian Floral Ware is divided into two sub-styles: the Northern Style and the Southern Style. The Northern Style is thought to have been produced in the area North and West of the Kopais while the Southern Style was chiefly produced in the Thespiai-Thebes and the Tanagra regions. To date our understanding of the development of the Southern Style has been based on systematically excavated floral evidence from Rhitsona (Ancient Mykalessos) and the Thespian Polyandrion and random vases from the Skhimatari Museum. Previous research incorrectly identified Tanagra as the primary source of Southern Floral Ware with little regard for Thebes as an important producer. Newly discovered ceramic evidence from four Theban cemeteries now indicates that Thebes was in fact a major producer of Floral Ware. The excavations have brought to light new floral groups and have provided evidence which indicates that vases previously identified as Tanagran or Euboian are more likely to be Theban.This dissertation chronicles the morphological and iconographical development of the Southern Floral Style according to the systematically excavated floral vases from Rhitsona and the Thespian Polyandrion. Rim and base profiles from the Thespian Polyandrion, Thebes and Haliartos are classified and floral motifs from datable contexts are assigned to types. The evidence indicates that it is the overall shape of the vase and the decorative details within the compositions, rather than a specific rim or base type or compositional layout that identifies regional differences, if any. Newly excavated vases from Haliartos are presented not only to provide a contrast for the Southern Style Floral Ware, particularly in terms of their shape, but also in order to establish a bridge between this dissertation and any future studies of the Northern Style Floral Ware.
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Li, Ji. "Modèle dans le domaine temporel et la validation expérimentale d’un scanner ultrasonore à ondes de surface sans contact." Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0026/document.
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Ce travail de recherche propose l’algorithme de calcul pour la modélisation d’un scanner ultrasonore sans contact à ondes de surface. L’approche proposée permet de prendre en compte l’ouverture finie du récepteur, l’atténuation d’air et la réponse électrique he de l’ensemble émetteur-récepteur. Le milieu avec l’atténuation (air et milieu testé) est modélisé dans le domaine temporel à l’aide de la fonction de Green causale permettant la caractérisation large bande. Le réponse he est déterminée de manière expérimentale en utilisant la procédure spatialement développée, incluant la déconvolution des effets d’atténuation. Le modèle est implémenté numériquement en utilisant l’approche de la Représentation Discrète et les résultats obtenus sont validés expérimentalement. La technique chirp est utilisée afin d’améliorer le rapport signal/bruit. Il est démontré que lorsque l’atténuation dans l’air, la dimension de récepteur et la réponse he reconstituée avec précision sont correctement pris en compte, la réponse impulsionnelle du système peut être prédite avec l’erreur de 2-5 %. L’introduction de la taille du récepteur est essentielle pour la prédiction dans le champ proche. Le temps de calcul obtenu est considérablement plus court que le temps nécessaire pour les méthodes FEM. A l’aide de ce modèle l’influence des réglages du scanner est étudiée. Les résultats obtenus permettent de formuler des recommandations pour les réglages optimauxIn this research the time-domain model for the prediction of an acoustic field in an air-coupled, non-contact, surface wave scanner is proposed. The model takes into account the finite size of the aperture receiver, attenuation in air, and the electric response he of the emitter-receiver set he. The attenuation is characterized by a causal time-domain Green’s function, allowing the wideband attenuation of a lossy medium (air and solid tested sample) obeying the power law to be modelled. The response he is recovered experimentally using an original especially developed procedure which includes the deconvolution of air absorption effects. The model is implemented numerically using a Discrete Representation approach and validated experimentally. In order to improve the signal to noise ratio the chirp technique is used. It is shown that when the attenuation in air, the receiver size, and the accurately recovered response he, are correctly taken into account, the model allows the system’s impulse response to be very accurately predicted, with errors ranging between 2-5%. Inclusion of the size of the receiver dimension in the model appears to be crucial to the accuracy of the near field predictions. The obtained computation efficiency is much better that efficiency of FEM methods. The influence of typical user defined settings has been investigated. The obtained conclusions will be used as the recommendations for further use
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Vlassis, Minas G. "Wage and employment determination as a multistage bargain : theory and evidence from the Greek manufacturing sector." Thesis, University of Essex, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290900.
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Freire, MÃrcio de Melo. "Teoria de funÃÃes de Green para uma impureza isolada localizada intersticialmente em sistemas ferromagnÃticos." Universidade Federal do CearÃ, 2017. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=18807.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoUm formalismo da funÃÃo de Green à usado para calcular o espectro de excitaÃÃes associadas com uma impureza magnÃtica localizada intersticialmente em diferentes estruturas ferromagnÃticas descritas pelo modelo de Ising e de Heisenberg. No capÃtulo 3, descrevemos um ferromagneto de rede cÃbica simples semi-infinita atravÃs do modelo de Ising. Neste caso, as excitaÃÃes nÃo-ressonantes (isto Ã, os modos de defeito fora da regiÃo das ondas de spin de volume e de superfÃcie) e as excitaÃÃes ressonantes (os modos de defeito dentro da regiÃo das ondas de spin de volume) sÃo calculadas numericamente para a fase de alta-temperatura. Duas situaÃÃes sÃo analisadas, dependendo da posiÃÃo da impureza em relaÃÃo a seus vizinhos: a impureza està na superfÃcie; a impureza està na regiÃo de volume. Nos demais capÃtulos, usamos o modelo de Heisenberg/Ising (onde passamos do modelo de Heisenberg para o de Ising atravÃs do controle de um parÃmetro) para descrever os seguintes sistemas: ferromagneto de rede quadrada infinita (capÃtulo 4), ferromagneto de rede quadrada centrada infinita (capÃtulo 5), ferromagneto de rede cÃbica de corpo centrado infinita (capÃtulo 6) e rede favo de mel infinita (capÃtulo 7), todos contendo uma impureza magnÃtica localizada intersticialmente. Nos trÃs primeiros casos, sÃo calculados apenas os modos de defeito acima da banda de volume do material puro (modos Ãpticos). No capÃtulo 7, sÃo analisados apenas os modos de defeito abaixo da banda de volume do material puro (modos acÃsticos).
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Carvalho, Paulo Gustavo Serafim de. "Equação reduzida para ondas curtas na superfície da água /." São Paulo : [s.n.], 2003. http://hdl.handle.net/11449/91861.
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Orientador: Roberto André KraenkelBanca: Gerson Francisco
Banca: Samuel Maier Kurcbart
Resumo: Estuda-se o comportamento de ondas de superfície em um fluido invícido no limite de curtos comprimentos de onda e levando em conta efeitos não-lineares. Uma equação para este limite é obtida e algumas soluções são exibidas.
Abstracts: The behaviour of surface-waves on a inviscid fluid is studied in the short-wave limit, taking nonlinear effects into account. An equation describing this limit is obtained and some of its solutions exibited.
Mestre
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Morvan, Antoine. "Impact sur le pont mouillé d’un navire SWATH pour la maintenance des éoliennes offshore." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0003.
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L’objectif de ces travaux de thèse de doctorat est de développer des modèles simplifiés d’impact hydrodynamique sur le pont mouillé d’un SWATH pour la maintenance des éoliennes offshore. La connaissance des chargements hydrodynamiques auxquels est soumis le pont mouillé est une étape primordiale lors de la conception de l’étrave du navire. Pour réaliser cette étude nous avons choisi une géométrie bidimensionnelle parabolique symbolisant le pont mouillé et une houle d’Airy régulière pour la surface libre. Les modèles développés reposent sur le modèle de Wagner qui permet d’obtenir des résultats pertinents pour un faible temps de calcul. Deux types de modèles d’impact ont été développés. Des modèles dits asymptotiques car ils reposent sur un développement de Taylor du profil de houle et des modèles non-asymptotiques car ils conservent la forme complète de la houle. Les distributions de pression sur le profil parabolique sont majoritairement calculées au moyen du formalisme Modified Logvinovich Model (MLM). Les résultats en termes de corrections de surface mouillée, de champs de pression et d’efforts hydrodynamiques sont comparés entre les deux types de modèles en fonction du rayon de courbure de la houle. Nous déterminons aussi quel est la configuration d’impact qui engendre les chargements hydrodynamiques dimensionnants en se basant sur des configurations de référence. Pour les modèles non-asymptotiques, la contribution de l’amplitude et de la vitesse de phase de la houle au sein des efforts hydrodynamiques est analysée. Pour les modèles asymptotiques, nous avons réalisé l’étude des variations spatiales et temporelles des champs de pression calculés avec l’équation de Bernoulli linéarisée. Nous avons aussi comparée les résultats du formalisme composite (COMP) au formalisme MLM et leurs conséquences sur les efforts hydrodynamiques d’impact. Enfin, dans le but d’avoir une base de comparaison pour ces modèles d’impact sur houle d’Airy régulière, nous avons implémenté des modèles numériques d’impact au moyen du logiciel commercial ABAQUS/CAE. Ces modèles reposent sur un couplage CEL (Coupled Eulerian-Lagrangian) et ont montré une bonne correspondance avec les résultats des modèles non-asymptotiques en termes d’écarts relatifs. Au sein d’un bureau d’étude, l’intégralité de ces résultats peut constituer une aide au dimensionnement du pont mouillé d’un navire SWATHThe aim of this PhD thesis is to develop simplified models about hydrodynamic impact (slamming) on the wet deck of a SWATH vessel for the maintenance of offshore wind turbines. The knowledge of the hydrodynamic loadings that the wet deck is subjected is an essential step in the design of the vessel’s bow. To realise this study we chose a parabolic twodimensional geometry which symbolises the wet deck and a regular Airy wave for the moving free surface. The models developed are based on the Wagner theory which provides relevant results for a low computational time. Two types of impact models have been developed. So-called asymptotic models, because they use a Taylor expansion of the wave profil and non-asymptotic models because they retain the whole shape of the wave. The pressure distributions on the parabolic shape are mainly calculated by the Modified Logvinovich Model (MLM). The results in terms of wetted corrections, pressure fields and hydrodynamic loadings are compared between the two types of models as a function of the wave radius of curvature We also determine the hydrodynamic impact arrangement which produces the highest hydrodynamic loadings by using reference configurations. For non-asymptotic models, the contribution of wave amplitude and phase velocity within hydrodynamic loadings is analysed in details. For non-asymptotic models, we made the study of the spatial and time variations of pressure fields computed with the linearized Bernoulli equation. We also compared the results of composite theory (COMP) to MLM theory and their consequences on hydrodynamic loadings. Finally, in order to get a basis of comparison for these regular Airy wave impact models, we implemented a numerical model using ABAQUS/CAE software. This model is based on a Coupled Eulerian-Lagrangian (CEL) coupling and show good matching with the results of non-asymptotic models in terms of relative errors. In a design office, all those results can be used to help design of the wet deck of a SWATH vessel
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Silva, Jonathan Esteban Arroyo. "Uma técnica explícita de marcha no tempo para ondas elásticas baseada em funções de Green calculadas localmente pelo MEF." Universidade Federal de Juiz de Fora (UFJF), 2014. https://repositorio.ufjf.br/jspui/handle/ufjf/3500.
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FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
Este trabalho apresenta um novo esquema de marcha no tempo capaz de reduzir oscilações espúrias através de amortecimento numérico para problemas de propagação de ondas elásticas no âmbito da Aproximação Explícita de Green (\Explicit Green's Approach" (ExGA)) [1]. A expressão integral referente ao ExGA é escrita em termos das funções de Green e Degrau. Seus cálculos são realizados de forma independente por meio da formulação semi-discreta do MEF e o método Diferença Central. Devido ao princípio da causalidade, as funções de Green e Degrau possuem um suporte compacto ao redor dos pontos fonte para um intervalo de tempo suficientemente pequeno que é usualmente Empregado nos métodos explícitos clássicos de integração temporal aplicados à modelagem de propagação de ondas. Neste sentido, as funções de Green e Degrau em t = Δt podem ser eficientemente calculadas localmente através de subdomínios pequenos. Cada subdomínio local com sua respectiva submalha cobre somente pontos nodais onde os valores das funções de Green e Degrau são não nulos. A precisão e eficiência da metodologia proposta é demostrada ao analisar três exemplos numéricos.
This work presents a new time-marching scheme able to reduce spurious oscillations by means of numerical damping for elastic wave propagation problems in the framework of the Explicit Green's Approach (ExGA) [1]. The integral expression concerned with the ExGA is written in terms of the Green's and the Step response functions. Their computations are carried out independently by means of the semidiscrete FEM and the Central difference method. Due to the principle of causality, the Green's and Step response functions admit a compact support surround the source points for a small enough time step that is usually employed in common explicit time integration methods applied to wave propagation modeling. In this sense, the Green's and Step response functions at t = Δt can be e ciently computed locally through small subdomains. Each local subdomain with its respective submesh covers only nodes whose Green's and Step response function values do not vanish. The accuracy and e ciency of the proposed methodology are demonstrated by analyzing three numerical examples.
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Blake, Daniel R. "Surface layer thickness and velocity determined using the Multi Channel Analysis of Surface Waves (MASW) method compared with microtremor resonance analysis-Federal Road, Greene County, Ohio." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1348429251.
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Dujardin, Alain. "Prédiction des mouvements du sol dus à un séisme : différences de décroissance entre petits et gros séismes et simulations large bande par fonctions de Green empiriques." Thesis, Nice, 2015. http://www.theses.fr/2015NICE4070/document.
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La prédiction des mouvements du sol générés par un séisme est un enjeu majeur pour la prise en compte du risque sismique. C’est l’un des objectifs du projet SIGMA dans le cadre duquel j’ai réalisé ma thèse. Celle-ci se compose de deux parties. La première se concentre sur la dépendance à la magnitude de la décroissance des paramètres des mouvements du sol avec la distance. Celle-ci est un sujet de préoccupation aussi bien pour l’utilisation des relations d’atténuation (GMPEs), que pour les méthodes basées sur l’utilisation de petits évènements en tant que fonctions de Green empiriques. Nous avons démontré qu’aux distances les plus faibles (inférieures à la longueur de la faille), l'effet de saturation dû aux dimensions de la faille est prépondérant. Aux distances plus importantes, l'effet de l’atténuation anélastique devient prépondérant. Nous avons donc montré qu’il pouvait être délicat de mélanger des données de différentes régions dans les GMPEs, et validé l’utilisation des fonctions de Green empiriques à toutes les distances. Dans la deuxième partie sont testées 3 différentes méthodes de simulations dans un contexte complexe : un code combinant une source étendue en k2 et des EGFs, un code point-source EGFs et un code stochastique. Nous avons choisi de travailler sur le séisme de magnitude Mw 5.9 (29 mai 2012) situé dans un bassin sédimentaire profond (la plaine du Po), et qui a engendré des sismogrammes souvent dominés par les ondes de surface. On y démontre que sans connaissance à priori du milieu de propagation, les méthodes basées sur des EGF permettent de reproduire les ondes de surface, les valeurs de PGA, de PGV, ainsi que les durées des signaux générésThe prediction of ground motion generated by an earthquake is a major issue for the consideration of seismic risk. This is one of the objectives of SIGMA project in which I realized my thesis. It consists of two parts. The first focuses on the magnitude dependence of the ground motion parameters decay with distance. This is a concern both for the use of relation of attenuation (GMPEs) than methods based on the use of small events as empirical Green functions. We have shown that as the shorter distances (less than the length of the fault), the saturation effect due to the fault size is preponderant. For larger distances, it’s the eanelastic attenuation effect which becomes predominant. So we have shown that it can be tricky to mix data from different regions in GMPEs and we validated the use of empirical Green functions at every distance. In the second part are tested three different simulation methods in a complex context: a code combining finite fault source in k2 and EGFs, a point-source code with EGFs and a stochastic code. We chose to work on the Mw 5.9 earthquake (May 29, 2012) which occurs in a deep sedimentary basin (the Po plain), and which has generated seismograms often dominated by surface waves. We show that without a priori knowledge of the propagation medium, methods based on EGFs can reproduce surface waves, the values of PGA, PGV, and the durations of the signals generated
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Chehami, Lynda. "Surveillance passive des milieux réverbérants par corrélation de bruit ambiant : application à la localisation de défauts." Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0035/document.
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La reconstruction passive des fonctions de Green par corrélation de bruit ambiant suscite aujourd’hui un grand intérêt en contrôle santé intégré (CSI). Dans ce manuscrit, nous proposons une méthode originale reposant sur l’application de cette approche pour détecter et localiser des défauts (fissures, trous, rainures) dans des plaques minces réverbérantes avec un faible nombre de capteurs. Les ondes de flexion qui se propagent sur la plaque sont engendrées soit par un ensemble de sources aléatoirement réparties sur la surface ou un bruit ambiant. Un réseau de capteurs sensibles au déplacement normal permet d’estimer la matrice de corrélations inter-éléments avant et après l’apparition d’un défaut. Un critère d’évaluation de la qualité des corrélations est proposé sous forme d’un niveau de bruit relatif entre les résidus de reconstruction et les fonctions de Green. La matrice différentielle de corrélations avant et après défaut est utilisée pour l’imagerie de défaut. En dépit de la reconstruction imparfaite des réponses impulsionnelles, la technique proposée s’avère comparable aux méthodes actives avec une excellente résolution. On a proposé ensuite une extension de la méthode passive par corrélation de champs pour l’identification des zones de bruit. Un filtrage basé sur la technique de décomposition en valeurs singulières (DORT) est tout particulièrement utilisé pour améliorer les images de localisation. Des sources acoustiques secondaires ont été développées pour la translation du bruit ambiant basses fréquences en composantes hautes fréquences, utilisées pour localiser des défauts dans des plaques. Enfin, on a montré que ce type de méthode pourrait être également utilisé pour caractériser un défaut dans une structure réverbérante, en particulier, il a été souligné que l’intensité des images de localisation obtenues est liée à la section de diffusion de celui-ciGreen’s functions retrieval from ambient noise correlation has recently drawn a new interest in structural health monitoring. In this manuscript, we propose an original method based on this approach to detect and locate defects (cracks, holes, grooves) in a reverberant thin plate with a limited number of sensors. Flexural waves that propagate on the plate are generated by either a set of sources distributed randomly on the surface or an ambient noise. Covariance matrices are estimated from the sparse array after damage and compared to baseline-correlation matrix recorded from the healthy plate. An evaluation criterion has developed in the form of relative noise level to predict the quality of the GF reconstruction. The differential correlation matrix w/o defect is used to localize the defect. We have shown numerically and experimentally that this technique is exploitable for defect detection and localization, despite a non-perfect estimation of the GF. We have also proposed a passive technique to identify the regions of noise. A filtering technique based on the singular value decomposition is shown to improve the detection. A secondary acoustic sources have been developped to harvesting the LF ambient noise to HF field, used to localize defects in platelike structures. Finally, it was shown that such method could also be used to characterize a defect in a reverberant structure, in particular, it has been drawn that the obtained images intensity is related to the defect cross-section
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KELNER, SYLVIE. "Etude de la propagation des ondes sismiques dans les milieux fissurés : atténuation, anisotropie et migration de fluide induite par un séisme." Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10284.
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La diffraction des ondes sismiques par des milieux fissures en deux dimensions (2d) est etudiee par une methode d'equations integrales aux frontieres ou les fonctions de green sont calculees par la methode des nombres d'ondes discrets (dwbiem : discrete wavenumber boundary integral equations method). Cette methode semi-analytique est particulierement bien adaptee aux problemes de la propagation des ondes sismiques dans un milieu homogene contenant des fissures vides ou remplies de fluide. Toutes les conversions d'ondes sont modelisees en appliquant la dwbiem. En premier lieu, nous avons etudie, par simulations numeriques, comment des milieux fissures pouvaient etre caracterises sismiquement. Nous avons ainsi pu observer des phenomenes d'attenuation et d'anisotropie, selon que la longueur d'onde du champ d'ondes incident est du meme ordre de grandeur ou qu'elle est plus grande que la longueur des fissures. Nous avons retrouve un resultat deja connu qui concerne l'attenuation des ondes elastiques lorsqu'elles traversent un milieu fissure : l'attenuation est maximale lorsque la longueur d'onde incidente est proche de la longueur des fissures. Par ailleurs, nous avons modelise la couche de granite fissuree du site de garner valley, en californie, en nous basant sur la theorie des milieux homogenes equivalents. Plusieurs modeles de milieux fissures restituent bien le taux d'anisotropie observe a garner valley. Une etude comparative de l'attenuation d'ondes s enregistrees la-bas et d'ondes s synthetiques permet de conclure que l'anisotropie s'explique par la presence de fissures verticales (et non horizontales) mais ne permet pas de privilegier un modele plus qu'un autre. Enfin, nous avons simule numeriquement la reponse hydro-mecanique d'un massif fracture a un seisme. Les deformations des fissures et les variations de pression dues au champ d'ondes rayonne par une faille en glissement permettent de connaitre les zones d'expulsion de fluide.
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Hussien, Elkhorbatly Bashar. "Modélisation, justification et analyse mathématique de modèles en océanographie." Thesis, Tours, 2019. http://www.theses.fr/2019TOUR4009.
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Cette thèse est consacrée à l’étude mathématique de la propagation d’ondes bi-dimensionnelles à la surface d’un fluide non visqueux irrotationnel et incompressible dont la surface libre n’agit que par la gravité et la tension superficielle dans un régime fortement non linéaire. La thèse est séparée en deux parties d’égale importance. Dans la première partie, nous justifions des modèles d’approximation plus précis du point de vue mathématique pour le problème des vagues, couramment utilisés en océanographie côtière pour décrire la propagation des ondes de surface de grande amplitude. On obtient un nouveau modèle asymptotique en eaux peu profondes du type Green-Naghdil incorporant les termes dispersifs d’ordre supérieur arbitraire tout en préservant la non-linéarité totale. Un résultat sur le caractère bien posé et une propriété de stabilité sont alors établis pour le cas unidimensionnel lorsque le fond est plat et non plat en tenant compte d’une faible tension de surface. Dans la deuxième partie, un résultat de stabilité orbitale est montré pour le peakon de Degasperis-Procesi dans le cas de perturbations ayant une densité de quantité de mouvement d’abord négative, puis positive. Ceci conduit à la stabilité orbitale du profil antipeakon- peakon vis-à-vis de telles perturbations et plus généralement d’un train de antipeakon-peakon bien ordonnésThis thesis is devoted to the mathematical study of the water-waves problem concerning two- dimensional motion of an irrotational and incompressible inviscid liquid with a free surface acted only by gravity and surface tension in a highly nonlinear regime. The thesis is separated into two parts of equal importance. In the first part, we justify mathematically more accurate approximation models for the water wave problem that are commonly used in coastal oceanography to describe the propagation of large amplitude surface waves. A new two-dimensional asymptotic shallow-water extended Green-Naghdi system is derived which incorporates the arbitrary higher-order dispersive terms while preserving the full nonlinearity. A well-posedness result and a stability property is then ensured for the one-dimensional case when the bottom is flat and not flat taking into consid- eration a small e
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del, Hougne Marc Philipp. "Shaping Green's Functions in Cavities with Tunable Boundary Conditions : From Fundamental Science to Applications." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC111.
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Cette thèse étudie le façonnage de champs électromagnétiques micro-ondes dans des cavités présentant des conditions aux limites reconfigurables. Le dispositif expérimental s'appuie sur une metasurface électroniquement reconfigurable qui couvre partialement les parois d'une cavité et qui permet ainsi de contrôler la façon dont les ondes y sont réfléchies. Le premier chapitre explore des aspects fondamentaux. D’abord, une étude paramétrique du façonnage d'un champ d'ondes électromagnétiques monochromatique et stationnaire en cavité est proposée en fonction d'un degré de contrôle introduit. Selon la valeur de ce paramètre, il est possible de concentrer de l'énergie en un endroit donné de la cavité de façon prédictible, de reconfigurer totalement cette cavité, ou bien de décider d'obtenir une résonance à une fréquence qui n'en supportait pas auparavant. Ensuite, l’imposition d’un comportement chaotique à une cavité de géométrie régulière est démontrée et une application au brassage des modes en chambre réverbérante est donnée. Dans la suite, la possibilité d’ajuster le couplage antenne-cavité est abordée, et une adaptation parfaite et dynamiquement configurable de l’impédance est proposée. Le reste du premier chapitre considère des champs transitoires. Dans un premier temps, la focalisation spatio-temporelle d’une impulsion fortement réverbérée dans une cavité en utilisant uniquement le contrôle spatial des ondes offert par la metasurface est démontrée, puis le lien avec le couplage entre les dégrées de liberté spatiaux et temporels du milieu de propagation est fait. Enfin, un dispositif permettant la reconfiguration répétée des conditions aux limites d'une cavité en un laps de temps inférieur au temps de vie des photons est réalisé, et des résultats préliminaires sont montrés. Dans le deuxième chapitre, des applications aux systèmes de communication sans fil multi-utilisateurs sont proposées. D’abord, dans la limite d’un bas facteur de qualité de la cavité, il est montré qu’un formalisme matriciel permet de décrire l’impact de la metasurface sur le champ. Cette matrice, mesurée sans information de phase, permet alors de focaliser le champ sur une ou plusieurs positions simultanément. Ensuite, la possibilité d’obtenir une diversité de canaux optimale (orthogonalité des canaux) en façonnant idéalement le désordre d’un milieu de propagation à l'aide de metasurfaces est établie. Finalement, le formalisme matriciel est utilisé afin d’introduire un concept de calcul analogique réalisé par le milieu désordonné en façonnant le front d’onde incident. Il est dès lors conclu qu’avec une infrastructure standard de Wi-Fi dans une maison, en combinaison avec une metasurface simple, cette idée peut être implémentée. Le concept est enfin transposé au domaine optique avec une fibre multimode. Au cours du troisième chapitre, quelques applications du façonnage d'ondes en milieux réverbérants aux capteurs des environnements connectés sont étudiées. D’abord, la possibilité de concentrer des champs électromagnétiques ambients sur des circuits redresseurs afin d’obtenir des tensions de sortie utiles est démontrée. De plus, grâce aux non-linéarités intrinsèques du redresseur, ceci est possible même sans avoir un retour direct du redresseur sur l’intensité du champ incident. Ensuite, un détecteur de mouvement hors ligne de vue et « intelligent » est proposé, qui profite d’un co-design de sa couche physique et du traitement de données. Enfin, il est démontré que même des objets non-coopératifs dans un environnement complexe peuvent être localisés grâce à leur contribution à la diffusion des ondes dans ledit milieu. L’équivalence d’utiliser la diversité fréquentielle ou bien le façonnage d’ondes dans ce contexte est établieIn this thesis, the shaping of microwave fields in chaotic cavities with tunable boundary conditions is studied experimentally. The experiments leverage a metasurface reflect-array that partially covers the cavity walls to tune the reverberation of waves inside the cavity. The first chapter explores several fundamental aspects. First, the achievable degree of control over stationary monochromatic wave fields is thoroughly investigated, and various regimes are identified, ranging from partial control over the wave field up to the limiting case of discrete resonances that can be tuned at wish. Next, the possibility to convert a cavity of regular geometry into one displaying chaotic characteristics by modulating the boundary conditions is examined and an application to non-mechanical mode-stirring in reverberation chambers is given. Then, the ability to tune the coupling between an antenna inside a cavity and the cavity itself is studied, revealing the opportunity of achieving (dynamically tunable) perfect impedance matching. The chapter goes on to consider spatio-temporal wave fields, and the re-focusing of such transient fields at a desired instant with the purely spatial control of the metasurface is demonstrated; moreover, the interplay of spatial and temporal degrees of freedom is addressed. Finally, an experimental platform enabling the rapid modulation of cavity boundary conditions within the photon lifetime is presented. The second chapter considers applications to multi-user wireless communication systems. First, it is shown that a matrix formalism to capture the impact of the metasurface on the wave field can be formulated in the regime of low reverberation, and even without access to phase information focusing on a single as well as on multiple targets is demonstrated. Second, it is shown that the channel diversity, which dominates the achievable capacity of information transfer, can be optimized by tweaking the environment’s disorder; perfectly orthogonal channels are obtained without any software or hardware efforts on the transmit or receive side, and the benefits of the implied minimal cross-talk are illustrated for the scenario of wirelessly transmitting a full-color image. Third, the matrix formalism is leveraged to propose a scheme of analog computation that counter-intuitively uses a disordered instead of a carefully tailored propagation medium, by appropriately shaping the incident wave front. A proof-of-concept demonstration suggests that combining ubiquitous Wi-Fi hardware in an indoor environment with a simple metasurface is sufficient to implement the concept. Finally, the concept is also implemented in the optical domain using a multimode fiber. The third chapter outlines a few applications for sensors in context-aware environments. First, it is shown that by shaping ambient wave fields, they may be concentrated on harvesting devices to increase the output voltage available for sensor powering; moreover, the non-linear nature of the harvesting device enables to do so without direct feedback from the target, using indirect feedback from the second harmonic. Second, a smart around-the-corner motion detector for complex environments is presented, enjoying a co-design of hardware and processing software by using a dynamic metasurface aperture; the latter is essentially a small (but still electrically large) disordered cavity with tunable boundaries that leaks tunable random radiation patterns that couple differently to the environment’s modes. Third, it is shown that objects may be precisely localized in complex environments even if they are non-cooperative by establishing signatures of their location that leverage their scattering contribution; this is demonstrated both with a frequency diverse and a wavefront shaping scheme, and the equivalence of the respective degrees of freedom is established
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Delestre, Olivier. "Simulation du ruissellement d'eau de pluie sur des surfaces agricoles." Phd thesis, Université d'Orléans, 2010. http://tel.archives-ouvertes.fr/tel-00587197.
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L'objectif de ce travail est le développement d'un modèle et d'une méthode numérique adaptés à la simulation du ruissellement d'eau de pluie sur des surfaces agricoles. Pour cela, nous utilisons un système d'équations aux dérivées partielles pour les eaux peu profondes : le système de Saint Venant. La pluie et l'infiltration y sont pris en compte par l'ajout de termes source et le couplage avec un modèle d'infiltration. Le système étant hyperbolique et conservatif nous choisissons d'utiliser un schéma aux volumes finis avec reconstruction hydrostatique. Avec cette reconstruction nous obtenons un schéma permettant de traiter les équilibres stationnaires et les interfaces sec/mouillé dues aux événements pluvieux. Tout d'abord, nous effectuons une comparaison systématique de différents flux numériques, de différentes reconstructions d'ordre deux (MUSCL et ENO modifiées) et de différentes méthodes de traitement des frottements sur des solutions analytiques unidimensionnelles. Ces comparaisons nous permettent de choisir une méthode numérique adaptée à la simulation du ruissellement qui en outre capture les phénomènes de type roll-waves. Ensuite nous nous intéressons au traitement de la pluie et de l'infiltration à l'aide du modèle de Green-Ampt. Cette méthode généralisée en dimension deux est validée sur des résultats expérimentaux obtenus à l'INRA d'Orléans et à l'IRD. La méthode numérique choisie et validée a été implémentée dans FullSWOF_2D un logiciel libre écrit en C++ pour la simulation de ruissellement d'eau de pluie sur des surfaces agricoles.
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Stellin, Filippo. "Anderson localization in interacting quantum systems." Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7004.
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Dans cette thèse nous étudions au niveau théorique le comportement des particules quantiques (électrons, atomes, photons, etc.) se mouvant dans un milieu désordonné et sujets à la localisation d’Anderson. Pour des particules non interagissantes, le spectre de l’énergie peut posséder un ou plus points critiques, où les fonctions d’onde étendues deviennent localisées, en donnant lieu à une transition de phase métal-isolant connue comme Transition d’Anderson.Une question fondamentale est si et comment les transitions d’Anderson survivent dans des systèmesquantiques interagissants. Dans cet ouvrage, nous étudions un modèle simple décrivant le cas de deux particules dans un réseau désordonné et sujettes à des interactions mutuelles à courte portée. En combinant des simulations numériques sur une grande échelle avec des techniques à la fonction de Green, nous montrons que les transitions d’Anderson à deux particules se produisent en trois dimensions et explorons le diagramme de phase dans l’espace de l’énergie, du désordre et de l’interaction.Cette dernière présente une structure riche, caractérisée par un double renfoncement de la limite de phase, engendrée par la compétition entre les états de diffusion et les états liés de la paire. Nous prouvons aussi que les annonces précédentes concernant l’apparition de transitions d’Anderson en deux dimensions étaient essentiellement dues à des effets de taille finie.Un deuxième problème que nous abordons dans cette thèse est celui de l’occurrence de transitions métal-isolant en deux dimensions pour une particule en la présence d’un potentiel spatialement corrélé et sujette à des interactions spin-orbite, modélisées par les couplages Rashba-Dresselhaus. On éclaire que, indépendamment des propriétés du désordre, il y a un régime où l’énergie critique dépend linéairement du paramètre de désordre. La pente et l’intercepte sont étudiées en voisinage du point de symétrie spin-hélice persistant, dans lequel la symétrie SU(2) est restaurée et la transition métal-isolant disparaîtIn this thesis we theoretically investigate the behaviour of quantum particles (electrons, atoms, photons, etc.) moving in a random medium and undergoing Anderson localization. For noninteractingparticles, the energy spectrum can possess one or more critical points, where the nature of the single-particle wavefunctions changes from extended to localized leading to a undergoes a metal-insulator phase transition, also known as Anderson transition.A fundamental question is whether and how Anderson transitions survive in interacting quantum systems. Here we study a minimal model of two particles moving in a disordered lattice and subject to short-range mutual interactions. By combining large-scale numerics with Green’s functions techniques, we show that two-particle Anderson transitions do occur in three dimensions and explore the phase diagram in the space of energy, disorder and interaction strength. The latter presents a rich structure, characterized by a doubly reentrant behavior, caused by the competition between scattering and bound states of the pair. We also show that previous claims of 2D Anderson transitions of the pair are essentially due to finite-size effects.A second problem that we address in this thesis is the occurrence of 2D metal-insulator transitions for a single particle in the presence of a spatially correlated potential and subject to spin-orbit interactions, described by Rashba-Dresselhaus couplings. We illustrate that, irrespective of the properties of the disorder, there is a regime where the critical energy depends linearly on the disorder strength. The slope and the intercept are studied in the vicinity of the spin-helix point, where the SU(2) symmetry is restored and the 2D metal-insulator transition disappears
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Harris-Birtill, Rosemary. "Mitchell's mandalas : mapping David Mitchell's textual universe." Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/12255.
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This study uses the Tibetan mandala, a Buddhist meditation aid and sacred artform, as a secular critical model by which to analyse the complete fictions of author David Mitchell. Discussing his novels, short stories and libretti, this study maps the author's fictions as an interconnected world-system whose re-evaluation of secular belief in galvanising compassionate ethical action is revealed by a critical comparison with the mandala's methods of world-building. Using the mandala as an interpretive tool to critique the author's Buddhist influences, this thesis reads the mandala as a metaphysical map, a fitting medium for mapping the author's ethical worldview. The introduction evaluates critical structures already suggested to describe the author's worlds, and introduces the mandala as an alternative which more fully addresses Mitchell's fictional terrain. Chapter I investigates the mandala's cartographic properties, mapping Mitchell's short stories as integral islandic narratives within his fictional world which, combined, re-evaluate the role of secular belief in galvanising positive ethical action. Chapter II discusses the Tibetan sand mandala in diaspora as a form of performance when created for unfamiliar audiences, reading its cross-cultural deployment in parallel with the regenerative approaches to tragedy in the author's libretti Wake and Sunken Garden. Chapter III identifies Mitchell's use of reincarnation as a form of non-linear temporality that advocates future-facing ethical action in the face of humanitarian crises, reading the reincarnated Marinus as a form of secular bodhisattva. Chapter IV deconstructs the mandala to address its theoretical limitations, identifying the panopticon as its sinister counterpart, and analysing its effects in number9dream. Chapter V shifts this study's use of the mandala from interpretive tool to emerging category, identifying the transferrable traits that form the emerging category of mandalic literature within other post-secular contemporary fictions, discussing works by Michael Ondaatje, Ali Smith, Yann Martel, Will Self, and Margaret Atwood.
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Jacobsson, Madeleine. "Dr. Eleine Mad." Thesis, Kungl. Konsthögskolan, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kkh:diva-587.
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Dr. Eleine Mad är Madeleine Jacobsssons talesperson för dom vetenskapliga och paranormala upptäckter som uppstår i hennes världar. Hon beskriver innehåll, teknik och estetik utifrån ett kategoriseringssytem där konsten delas upp som olika typer av komponenter och därefter avkodas dessa allteftersom. För att förstå intuitionens inblandning i arbetsprocessen omförvandlas den till tre separata roller av en Sökare, Samlare och Myntare. Med rollerna försöker jag beskriva på vilka sätt som intuitionen är till gagn eller av förödelse för det konstnärliga arbetet. Sagan om M handlar om en grodlik karaktär, Delop, som lämnar sin hemplanet för att uppsöka andra världar. I sitt sökande hittar Delop ett folkslag vars syn och levnadssätt skiljer sig från hennes erfarenheter av “verkligheten” såsom hon lärt sig att överleva i den.Dr. Eleine Mad is Madeleine Jacobsson's spokesperson for the scientific and paranormal discoveries that arise in her worlds. She describes content, tecniques and aesthetics based on a categorization system where art is divided into different types of components and then decoded as they go. To understand the intuition's involvement in the work process, it is transformed into three separate roles by a Seeker, Collector and a Myntare(In swedish language the one who is a "myntare" -is verbally declaring a concept or term). With these roles I try to describe in what ways intuition is beneficial or devastating to the artistic work. The story of M is about a frog-like character, Delop, who leaves the home planet to seek out other worlds. In her search, Delop finds a world whose views and lifestyles differ from her experiences of "reality" as she learned to survive in it.
Recorded sound and image material of the presentation is available for private use.
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Arango, Dario Eduardo Nuñez. "The green wave on the luxury automobile industry." Master's thesis, 2021. http://hdl.handle.net/10362/122603.
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Galarza, Carlos Alberto Guevara. "The green wave on the luxury automobile industry." Master's thesis, 2021. http://hdl.handle.net/10362/122799.
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Ramadanovic, Bojan. "Green Schwarz superstring on a pp-wave Ramond-Ramond background." Thesis, 2003. http://hdl.handle.net/2429/14631.
Full textAbstract:
The discovery of the dualities between the large N gauge theories and the string
theories on the particular curved backgrounds has made the later subject of
much study over the last decade. Of particular interest is the string theory on
AdSz, x S5 which was shown by Maladacena to be dual to the conformal Af = 4
super Yang-Mills theory. This string theory, however, is difficult to quantize
and it proved useful to work in the specific Penrose limit of the AdS$ x S5.
String theory on this limit, called pp-wave background, proved to be explicitly
quantizable and furthermore it turned out to be itself a dual of the particular
limit of the corresponding Conformal Field Theory. It became therefore an
important case for testing the principles of the AdS/CFT correspondence. The
properties of the string theory on this background have been studied extensively
by Metsaev and Metsaev and Tseytlin in the papers hep-th/0112044 and hepth/
0202109 and this thesis is mostly a review of their results. The type IIB
superstring action is constructed and quantized on the background and the
supergravity spectrum of the theory is found. Finally some results concerning
two-point functions and vertex operators, not given in Metsaev, are derived.
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Shen, Tsung-Yi, and 沈宗億. "Study of Green Wave in Virtual-Traffic-Light Environment through VANETs." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/40919956078178629913.
Full textAbstract:
碩士國立中央大學
資訊工程學系在職專班
101
Urban traffic congestion causes energy consumption and emissions. However, traditional traffic light is fixed time to change between green and red light. If traffic lights can dynamic change by traffic flow, drivers can go through a series of traffic lights with dynamic speed guidance over several intersections. Therefore, traffic management plays an important role in saving energy and improving vehicle speed. This study focuses on virtual traffic light and applies VANETs to support dynamic speed guidance to the drivers. Based on the speed information, we can achieve the goal of Green Wave so that energy consumption and emission reduction are minimized. Detailed are discussed the algorithm of green wave speed guidance and simulate in Taipei city. This study develops a green wave speed guidance strategy for virtual traffic light. As a traditional green wave speed guidance, any vehicle travels along with fixed speed. However, in the process of operation, the optimal speed advice to vehicle should take into consideration the current traffic conditions, road grade, etc. In this study, we presented an adjustable speed strategy based on a bi-directional intersection. According to traffic flow and the type of vehicles in the intersection decide dynamic speed guidance. Using VTL with V2V communication generates traffic signal “online” by vehicles. The dynamic speed control in virtual traffic light guides vehicle on the best running speed to go through serial intersections without stopping. Thus, green wave coordinated control reduces stop-and-go traffic and control signal to achieves real-time traffic smooth. As a case of study, the main road in Taipei is taken for simulation and evaluation in virtual traffic light. The simulation results compared with fixed signal show that, the performance of vehicle speed increased by about 47.2%. On the other hand, the improvement of throughput-to-volume increased by about 46%. As for the energy savings for vehicles with green wave speed guidance are found to be 39.1%.
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林鈺庭. "Continuous-wave solid-state green laser annealing in panel epi-like silicon transistors." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/49994949917453072424.
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博士國立交通大學
材料科學與工程系所
96
This dissertation explores and demonstrates enhanced electrical characteristics and reliability of continuous-wave green laser fabricated epi-like silicon transistors on non-silicon substrates, which greatly impacts on active-matrix no/off circuits, nonvolatile memories, linear image sensors, and photo-detector amplifiers for various panels and photonic circuits. The main focus of this dissertation can be divided into four parts. First, electrical characteristics of continuous-wave (CW) green laser-annealed single-grainlike silicon thin-film transistors in relation to trap-state densities were characterized. As laser power increases, highly crystalline channels form, reducing tail-state densities to as low as 3x1019 eV-1cm-3. This occurrence is responsible for high field-effect electron mobility of 284 cm2/Vs. In contrast, increasing laser power initially reduces the deep-state density and then increases it to 3x1016 eV-1cm-3. This reversal in deep-state density, and thus in the subthreshold slope, as well as a saturating reduction in threshold voltage are associated with the formation of extra interface defects caused by laser-crystallization-enhanced surface roughness. Next, stability of high hole-mobility thin-film transistors (TFTs) on single-grainlike silicon channels formed by CW laser-crystallization (CLC) during hot-carrier stressing (HCS) was studied. As channel layers become thicker, laser-mediated channel crystallinity increases, increasing channel roughness. On such epi-like polycrystalline silicon (poly-Si) substrates, the poorer interface quality for thicker channels, even those with lower tail-state densities of grain traps, is responsible for the extensive charge trapping and creation of deep-state densities in the fabricated TFTs due to HCS. Hence, on a thin channel with a thickness of 50 nm and ultra-smooth surfaces, HCS hardly degrades the electrical parameters of the devices. Third, the hole-mobility and reliability of green CW laser-crystallized epi-like Si transistors on glass panel substrates were enhanced by source/drain activation by back-side green laser-irradiation. Green laser-energy was scanned uniformly across junctions, since the gate structures included no interrupt, in an attempt to conduct super visible-laser lateral-activation. The enhancement was thus explained by the formation of continuous improved epi-like Si microstructures with reduced grain defects and with a barely increased number of interface defects over the entire channel/junction. The hole-mobility in such laser-activated devices was as high as 403 cm2/V.s – doubles that of thermally activated devices. Fourth, panel transistors were activated by front-side CW green laser irradiation. In self-aligned poly-Si TFTs, significant laser-energy penetrates through poly-Si gates owing to the considerably long penetration depth of green light in poly-Si. Green laser-energy was thus uniformly scanned laterally from channels to source/drain regions and, vice versa, in under a millisecond, hardly affected by gate structures. Such spike green-laser annealing yields low parasitic source/drain resistance and quasi-continuous improved poly-Si microstructures in green laser-activated TFTs, with reduced grain defects over the entire channel/junction. Electron-mobility and sub-threshold slope for such transistors that were fabricated on CLC channels of 100 nm, were remarkable values of 530 cm2/V.s and 120 mV/dec, respectively. In gate structures of TiN/SiO2, laser-activated panel transistors that were fabricated on CLC channels of 100 nm, also revealed electron-mobility as high as 230 cm2/V.s. In metal gated panel transistors, front-side CW green laser irradiation intrinsically activates source/drain regions selectively, because of light reflection by metal gates, causes little thermal damage on materials underneath metal gates, which endorses advanced panel or photonic transistors with compound, nanostructured, and functionalized gate dielectrics or polycrystalline materials. In future, those CW green laser-fabricated transistors will be routines for the development of panel photo-sensors and memories, as well as nano-photonic circuits.