Dissertations / Theses on the topic 'Edge velocity'
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Spitz, Nicolas. "Prediction of Trailing Edge Noise from Two-Point Velocity Correlations." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32637.
Full textMaster of Science
Eisenman, Adam. "Estimating light edge velocity based on retinal ganglion cell spike trains." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40323.
Full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 136-137).
This thesis is intended to present a specific sub-problem of a larger one we call the 'Inverse Problem'. We wish to estimate the velocity (speed and direction) of an edge of light which is moving on the photoreceptor layer of a rabbit retinal patch. We make these estimates based solely on the electrical response measured from the retinal ganglion cells (RGCs). We present various algorithms for doing so and present sensitivity analysis of such algorithms. We test the performance of the algorithms on data recorded from retina and on data produced by simulation. We find that we are able to extract enough information about the edge velocity from ON and OFF RGCs when the edge of light is wide. However, our best algorithm's performance decays significantly as the edge of light gets narrower. This leads us to develop algorithms that use ON-OFF directionally selective (DS) cells in conjunction with non-directional ON and OFF cells to produce better estimates of the velocity for narrow edges of light. In addition, we develop a model to simulate the response of a DS cell to 1-dimensional light motion.
by Adam Eisenman.
S.M.
Malhotra, Anjum. "Low velocity edge impact on composite laminates : damage tolerance and numerical simulations." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8571.
Full textJosefsson, Mattias. "3D camera with built-in velocity measurement." Thesis, Linköpings universitet, Datorseende, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-68632.
Full textI dagens industri används ofta 3D-kameror för att inspektera produkter. Kameran producerar en 3D-modell samt en intensitetsbild genom att sätta ihop en serie av profilbilder av objektet som erhålls genom lasertriangulering. I många av dessa uppställningar används en fysisk encoder som återspeglar hastigheten på till exempel transportbandet som produkten ligger på. Utan den här encodern kan bilden som kameran fångar bli förvrängd på grund av hastighetsvariationer. I det här examensarbetet presenteras en metod för att integrera funktionaliteten av encodern in i kamerans mjukvara. För att göra detta krävs att ett mönster placeras längs med objektet som ska bli skannat. Mönstret återfinns i bilden fångad av kameran och med hjälp av detta mönster kan hastigheten bestämmas och objektets korrekta proportioner återställas.
Sierchio, Jennifer Marie. "Comparison of edge turbulence velocity analysis techniques using Gas Puff Imaging data on Alcator C-Mod." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91073.
Full text30
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 117-119).
In the past, two methods for analyzing data from the Gas Puff Imaging diagnostic on Alcator C-Mod have been used. One uses temporal and spatial Fourier analysis to obtain wavenumber-frequency spectra, from which a phase velocity is computed [1, 2]. The other is based on time-delay cross-correlation of successive images used to track the motion of discrete emission structures [3, 4]. Several Gas-Puff-Imaging experiments were conducted to obtain data taken using the GPI Phantom Camera. The analysis of and results from these data are discussed in [3]. The results showed that the tracking time-delay-estimation technique found poloidal velocity magnitudes in the 0.1-1.4 km/sec range. However, independent examination of these data using the Fourier analysis yielded magnitudes up to a factor of 10 larger for the same data, and sometimes even disagreed with the direction of motion found. To understand the reasons for these discrepancies, we designed and generated synthetic data that mimics the real data. The user inputs the velocities, sizes, intensities, and distributions of the synthetic emission structures. We have used the synthetic data to test each code rigorously for strengths, weaknesses, and weighting. We have found that the Fourier analysis perfectly returns the correct poloidal velocity when there is no radial velocity component present. We have found that the tracking TDE analysis weights low frequency, low wavenumber features most heavily since they are typically the most intense, but systematically returns a smaller velocity than expected due to issues associated with averaging. After adjusting for these issues, the tracking TDE code now returns the correct value of the poloidal and radial velocities to within 10% for synthetic data as long as there is only one velocity present in the synthetic simulation. We applied these corrections to the analysis of the real data, and found that the measurements changed little in most cases. We then examined, in detail, the Fourier-analysis-derived "conditional" spectra for each shot, and determined that the likely causes for the discrepancies are due either to multiple velocities with emission structures moving in opposite directions in the same field of view or to non-zero "dispersion" in which lower-frequency/lower-wavenumber features are moving with one phase velocity and higher-frequency/higher-wavenumber features are moving with a different phase velocity. In a couple of cases, there may be a radial component in the actual images that may affect the poloidal velocity measurement for the Fourier analysis. Accounting for these explanations, we believe that we have resolved the discrepancies in many cases, and can explain it in the others.
by Jennifer Marie Sierchio.
S.M.
Glenn, Timothy Scott 1971. "Velocity measurement of laser energy induced Rayleigh surface waves on bulk substrates employing the optical beam deflection (knife-edge detection) method." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/49947.
Full textWhitehouse, David Richard Carleton University Dissertation Engineering Aerospace. "The effect of axial velocity ratio, turbulence intensity, incidence and leading edge geometry on the off-design performance of a turbine blade cascade." Ottawa, 1993.
Find full textAbraham, Rohit Mathew. "An Experimental Study of Scuffing Performance of a Helical Gear Pair Subjected to Different Lubrication Methods." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397228984.
Full textLeybros, Robin. "Etude des vitesses de dérive fluides dans le plasma de bord des tokamaks : modélisation numérique et comparaison simulation/expérience." Thesis, Ecole centrale de Marseille, 2015. http://www.theses.fr/2015ECDM0006/document.
Full textThe transport of heat and particles in the edge of tokamaks plays a key role in both the performance of the confined plasma and the extraction of power and thus the lifetime of the plasma facing components. It’s in this context that this thesis is inscribed, which focuses on the role played by the transverse magnetic field flows in the balance between parallel and perpendicular dynamic that governs the edge region of a tokamak. These flows can produce poloidal asymmetries of heat and particles deposit on plasma facing components and generally asymmetries of various amounts in plasma. The radial drift velocities are due to the presence of a radial electric field resulting from charge balance (electric drift velocity) or related to effects of the toroidal geometry inducing a magnetic field inhomogeneity (curvature drift velocity). To advance the understanding of these phenomena, numerical modeling of transport and turbulence in complex geometries is essential. In addition, synthetic diagnostic tools for modeling the measurement process in numerical plasmas are developed to enable a realistic comparison between models and experiments. Modeling of perpendicular drift velocities was introduced into the SOLEDGE2D code describing the transport of the density, momentum and energy of a tokamak plasma. We first studied the impact of a prescribed electric field on plasma equilibrium to understand the mechanisms behind plasma asymmetries and study the establishment of parallel flows and asymmetry of the heat flux on plasma facing components. Then we implemented a self-consistent model solving the electric potential in SOLEDGE2D fluid equations to understand the equilibrium of the electric field and to study the effect of the magnetic configuration of the tokamak and the curvature drift velocity on it. In the second part of this thesis, a synthetic diagnosis modeling the experimental measurements of Doppler backscattering was developed and tested in order to be applied to simulations of 3D turbulent fluid code TOKAM3X. This diagnosis measures the perpendicular velocity of the plasma from the movement of the density fluctuations. It was used to compare the perpendicular velocity asymmetries observed experimentally to asymmetries measured in numericalsimulations
Lismonde, Baudouin. "Champ de vitesse au bord d'attaque et dans le spot laminaire d'un écoulement sur une plaque plane." Grenoble 1, 1987. http://www.theses.fr/1987GRE10074.
Full textLindeberg, Tony. "Discrete Scale-Space Theory and the Scale-Space Primal Sketch." Doctoral thesis, KTH, Numerisk analys och datalogi, NADA, 1991. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-58570.
Full textQC 20120119
Cantoni, Lorenzo. "Load Control Aerodynamics in Offshore Wind Turbines." Thesis, KTH, Kraft- och värmeteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291417.
Full textPå grund av ökningen av rotorstorleken hos horisontella vindturbiner (HAWT) under de senaste 25 åren, en design som har uppstod för att uppnå högre effekt, måste alla vindkraftkomponenter och blad stå emot högre strukturella belastningar. Detta uppskalningsproblem kan lösas genom att använda metoder som kan minska aerodynamiska belastningar som rotorn måste tåla, antingen med passiva eller aktiva styrlösningar. Dessa kontrollanordningar och tekniker kan minska utmattningsbelastningen på bladen med upp till 40 % och därför behövs mindre underhåll, vilket resulterar i viktiga besparingar för vindkraftsägaren. Detta projekt består av en studie av lastkontrolltekniker för havsbaserade vindkraftverk ur en aerodynamisk och aeroelastisk synvinkel, i syfte att bedöma en kostnadseffektiv, robust och pålitlig lösning som kan fungera underhållsfri i tuffa miljöer. Den första delen av denna studie involverar 2D- och 3D-aerodynamiska och aeroelastiska simuleringar för att validera beräkningsmodellen med experimentella data och för att analysera interaktionen mellan fluiden och strukturen. Den andra delen av denna studie är en bedömning av de ojämna aerodynamiska belastningarna som produceras av ett vindkast över bladen och för att verifiera hur en bakkantklaff skulle påverka de aerodynamiska styrparametrarna för det valda vindturbinbladet.
Marin, Ospina Yohan Manuel. "Etude de l'influence de la dilution du combustible et de l'oxydant dans le processus de décrochage de flammes-jet non-prémélangées et l'émission de polluants." Thesis, Rouen, INSA, 2016. http://www.theses.fr/2016ISAM0025/document.
Full textUnderstanding the main mechanisms piloting non-premixed jet flame stability is an important point in characterizing the operation modes of industrials burners in which dilution is involved. This work puts special emphasis on the experimental study of the influence of air-side and methane-side dilution in the lifting process of attached non-premixed jet flames. The study is based on numerous experiments combining the following conditions : i) carbon dioxide (CO2), nitrogen (N2), argon (Ar) or water vapor (H20v,) used as diluents d ; ii) two diluted configurations : air-side or methane-side dilution ; iii) two air and fuel velocities covering the entire flame hysteresis domain, from the laminar to the turbulent regime. This allows the influence of the intrinsic diluent nature effects to be discriminated from those of the aerodynamics of the reactants (fuel and oxidant), in attached flame stability. In particular, the behavioral differences of the flame response to air-side or to fuel-side dilution are analyzed. These two configurations differ by two mixing effects which are independent of the combustion reaction, and which are significant when the fuel is diluted, but negligible when air is diluted : i) an effect due to the changes in the stoichiometric mixture fraction ; ii) a mechanical impact induced by the addition of matter (diluents) producing an increase in the bulk velocity of the reactants. The study is composed of three parts. First, the global flame response to dilution is analyzed on the basis of the lifting limits defined as the critical molar fractions of the diluents in the fuel or in the oxidant measured at liftoff. The fuel Peclet number, Pef, appears as the dimensionless number which puts these limits in a homothetic order. This homothetic behavior allows the introduction of two affinity parameters, Kd,ox for air-side dilution and Kd,f for fuel-side dilution. They are defined by the ratio of the flame lifting limits calculated with a diluent d and with CO2, at Pef=const. Kd,ox and Kd, allow two generic polynomial laws to be established describing the flame lifting limits for all the diluents and in the whole range of aerodynamic conditions of this study. Indeed, Kd,ox and Kd,f encompass all the diluent effects affecting flame stability (pure dilution, thermal, transport, chemical), to which mechanical impacts are added. These coefficients make it possible to obtain the self-similarity laws of the lifting limits for any chemically-weak diluent, by using the results obtained in this work. Then, a local and detailed study of the flame lifting process induced by dilution is presented. This is based on the flame-leading-edge approach describing flame stability as a result of the balance between the incoming gas velocity of the reactants and the flame propagation velocity at the flame base. In order to show the link between this approach and flame stability, an extensive analysis of the flame-base characteristics (location, CH* emission intensity and velocity field) is carried out. The results attest to the pertinence of the propagative flame-leading-edge, as the mechanism describing the attached flame stability under dilution. Finally, a study concerning the influence of both the diluent nature and the diluted configuration (air or fuel) on pollutant emissions (soot, NOx and CO) is presented
Ležovič, Tomáš. "Experimentální analýza proudu vzduchu z ofukovače osobního vozu s využitím žárového anemometru a návrh hodnocení kvality ofukovače." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229643.
Full textKunze, Claudia. "Acoustic and velocity measurements in the flow past an airfoil trailing edge." 2004. http://etd.nd.edu/ETD-db/theses/available/etd-04022004-092958/.
Full text"Effects of edge safety factor on the toroidal flow velocity of the STOR-M plasma." Thesis, 2015. http://hdl.handle.net/10388/ETD-2015-02-1962.
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