Дисертації з теми "Low-dispersion"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Low-dispersion".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Johnston, William F. (William Francis). "A low dispersion 2-GHz comparator." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/36781.
Повний текст джерелаIncludes bibliographical references (leaves 40-41).
A low dispersion 2-GHz comparator is an essential part of the latest automated VLSI tester by Teradyne Inc. With each new and faster CMOS logic VLSI microchips, faster and more precise comparators are needed to verify that the static discipline is being met on the many pins of the integrated circuit. As the error in the comparator is lowered, the VLSI production yield is greatly increased because of greater certainty of the measurements. The comparator described within is designed to test a variety of CMOS logic levels at the expected logic levels and rise-times of the near future. The result is a Si-Ge integrated comparator with 12psec of dispersion by detailed simulation awaiting fabrication. Index Terms-Complementary metal oxide semiconductor transistor technology (CMOS technology), very large scale integration (VLSI), application specific integrated circuit (ASIC), silicon germanium (Si-Ge), integrated circuits (IC), automatic test equipment (ATE), personal computer (PC), digital signal processing (DSP), direct current (DC), alternating current (AC), device under test (DUT), pin electronics (PE), bipolar junction transistors (BJT), complementary metal oxide semiconductor field effect transistor (MOSFET).
by William F. Johnston.
M.Eng.and S.B.
Hao, Ran. "Wide-band low-dispersion low-losses slow light in photonic crystal waveguides." Paris 11, 2010. http://www.theses.fr/2010PA112351.
Повний текст джерелаThis Ph. D study brings contributions of solving present problems for slow light in photonic crystal waveguides, aiming to obtain wide-band, low-dispersion, and low losses slow light. Novel kinds of photonic crystal waveguides are proposed having large bandwidth, low group velocity dispersion and allowing a flexible control of slow light properties with reasonable requirements to clean room fabrication. An overall approach to improve the delay-bandwidth product of present slow light devices is proposed. By using this approach, the normalized delay-bandwidth product of previous waveguides has been improved by a factor of 15 if compared with regular photonic crystal waveguides with a group index maintained at the high value of 90. The fabrication induced losses have also been studied. We modeled four kinds of structure disorders in real fabrication. The obtained results quantify how much the region close to the line defect center has a dominant influence on the losses. Finally, all design results have been used for the fabrication of silicon-on-insulator samples prepared for the demonstration of the foreseen slow light effects
Nazari, Farshid. "Strongly Stable and Accurate Numerical Integration Schemes for Nonlinear Systems in Atmospheric Models." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32128.
Повний текст джерелаSodhi, Hemraj Singh. "Measuring and modeling low frequency dispersion in GaAs MESFETs." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38134.
Повний текст джерелаIncludes bibliographical references (p. 79).
by Hemraj Singh Sodhi.
M.Eng.
Biasi, Verner de. "The application of low dispersion liquid chromatography in the pharmaceutical industry." Thesis, Open University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259485.
Повний текст джерелаNance, Douglas Vinson. "Finite volume schemes optimized for low numerical dispersion and their aeroacoustic applications." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/12110.
Повний текст джерелаWang, Gang. "Study of a low-dispersion finite volume scheme in rotocraft noise prediction." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/12395.
Повний текст джерелаZhao, Min. "The Development of Spray Dried Solid Dispersion Systems for the Formulation of Low Tg and Low Solubility Drugs." Thesis, University of East Anglia, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527643.
Повний текст джерелаMedeiros, Nicholas J. "Computational Fluid Dynamics Simulations of Radial Dispersion in Low N Fixed Bed Reactors." Digital WPI, 2015. https://digitalcommons.wpi.edu/etd-theses/1306.
Повний текст джерелаNidzieko, Nicholas James. "Dynamics of a seasonally low-inflow estuary : circulation and dispersion in Elkhorn Slough, California /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Повний текст джерелаMørtsell, Eva Anne. "Dispersion hardening during annealing at low Temperatures in four 3xxx Al-Mn-Fe-Si Alloys." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16808.
Повний текст джерелаAbdala, Mohammed Ahmed. "Characterisation of traps in GaAs MESFETs by low frequency noise, gM dispersion and oscillations methods." Thesis, Lancaster University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315539.
Повний текст джерелаPölder, Robert. "Wage Dispersion and Employment for People With Low Skill : Sweden Compared to Six European Countries." Thesis, Linnéuniversitetet, Institutionen för nationalekonomi och statistik (NS), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-55590.
Повний текст джерелаSuherman, Phe Man. "A novel dielectric technique for monitoring the lyophilisation of globular proteins." Thesis, De Montfort University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369908.
Повний текст джерелаVelez, Dianna M. (Dianna Maria). "System level dispersion analysis examining program benefits to a low-thrust interplanetary CubeSat from autonomous guidance and navigation." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107055.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 162-165).
Ground based measurements through the Deep Space Network (DSN) are unlikely to be available as often for CubeSats as for prior deep space programs because higher priority missions will take precedence for access to the limited and expensive DSN resource. Consequently, to make the most of CubeSats in deep space, dependence on the ground must be minimized. In this research a closed-loop Linear Covariance (LinCov) analysis was performed to quantify the effects of the guidance and navigation (GN) system on trajectory dispersions for a low-thrust CubeSat in route to entry-interface conditions at Mars. Applicable mission plan concepts, appropriate analysis settings, as well as required mission performance used in the analysis were based on input collected from industry as well as criteria from prior Mars missions and the Deep Space 1 mission. Information was gathered regarding expected ground-derived orbit determination accuracy levels as a function of decreased DSN use. Optical navigation based on line-of-sight measurements of Mars was then investigated as a means to maintain onboard navigation accuracy despite reduced DSN coverage. The ability of onboard optical navigation to reduce needed ground tracking frequency and associated costs was found practical for interplanetary cruise. The expected resulting financial benefits from decreased DSN were quantified. Recommendations for onboard GN system capabilities and mission goals are made. LinCov was also explored as the core of a basic onboard mission planner that could enable more autonomous CubeSat interplanetary trajectory management.
by Dianna M. Velez.
S.M.
Gustafsson, Stefan. "Electromagnetic dispersion modeling and analysis for HVDC power cables." Licentiate thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-32525.
Повний текст джерелаChiu, Yu-yeung. "Environmental radiation monitoring at the low level radioactive waste storage facility in Siu A Chau and development of a particle dispersion model in marine environment." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B38573611.
Повний текст джерелаCorrea, Loup. "Measurement of the generalized polarizabilities of the proton by virtual Compton scattering at MAMI and Q² = 0.2 GeV²." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22727/document.
Повний текст джерелаThis work presents the measurement of the generalized electric αE(Q2) and magnetic βM(Q2) polarisabilities (GPs) of the proton. The GPs are defined in the Virtual Compton Scattering (VCS) context, i.e. the reaction γ*p → γp where Q2 is the four-momentum transfer of the virtual photon. The GPs are a generalization of polarizabilities measured in real Compton scattering (RCS) by taking into account the Q2-dependency. They are dynamical properties of the proton when it is deformed by an applied electromagnetic fiels. αE(Q2) (or βM(Q2)) gives access to the local polarization (or magnetization) density of the deformed proton. The studied VCS process is accessible by the photon-electroproduction reaction (ep → epγ). The GP effect is a 1 – 15 % contribution to the ep → epγ cross section, requiring a high-precision mleasurement. The present work is a part of an experiment conducted by the A1 collaboration at MAMI at three new Q2 values : 0.1,0.2 and 0.45 GeV 2. This thesis details the extraction at 0.2 GeV 2. The experiment uses the 1 GeV electron beam, the 5 cm liquid hydrogen target and spectrometers A (B) to detect the final electron (proton). The first-level analysis includes a detailed calibration of experimental data, and the use of a simulation of the experiment. The measurement of the unpolarized ep → epγ cross section is described with two of its important features : the correction of the radiative effects and the renormalization. Two differents frameworks are used to extract the GPs : the Low Energy Theorem (LET) and the dispersion relation model (DR). The two extractions lead to results in good argument. The world data still raises question about the Q2-behavior of the Gps
Pathak, Mihir Gaurang. "Thermal dispersion and convective heat transfer during laminar pulsating flow in porous media." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34738.
Повний текст джерелаWannberg, Veronica Elaine. "Quantitative Uncertainty of Chemical Plume Transport in Low Wind Speeds Using Measured Field Data and Stochastic Modeling." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2570.pdf.
Повний текст джерелаWu, Jiedi. "New Constraints on Fault-Zone Structure from Seismic Guided Waves." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28873.
Повний текст джерелаPh. D.
Souzy, Mathieu. "Mélange dans les suspensions de particules cisaillées à bas nombre de Reynolds." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4719/document.
Повний текст джерелаMainly based on experiments, I investigated at a particle scale the mechanisms at the origin of the transfer enhancement in sheared non-Brownian and non-inertial particulate suspensions. First, I revisited Taylor's experiment, investigating the evolution of a drop of dye in a periodic shear. Beyond a critical strain amplitude, the presence of the particles breaks the reversibility of the system and the drop of dye is rapidly dispersed in the surrounding medium. Then, investigating the transfer process in the wall vicinity, I showed that in this region, the rotation of the particles convectively transport a scalar at a constant rate directly from the wall towards the bulk of the suspension, breaking the diffusive boundary layer. An analytical solution for the concentration profile in this region is proposed, in good agreement with experimental measurements. Lastly, high-resolution PIV measurements of the fluid phase were performed in the bulk of the suspension. Using these velocity fields, we reconstructed the stretching histories of fluid material lines to determine the stretching laws, crucial for the understanding of the mixing process. The presence of the particles changes the very nature of the stretching laws from linear, in a pure fluid, to exponential in the presence of particles. A multiplicative stretching model is proposed, which quantitatively predicts the experimentally measured evolution of the mean and the variance of the elongations of the fluid material lines as well as their evolution towards a log-normal distribution. The strong stretching inhomogeneity in sheared suspensions results in a broad distribution of the mixing time
Ljubica, Dokić-Baucal. "Uticaj molekularnih svojstava maltodekstrina na tehnološko ponašanje niskoenergetskih prehrambenih emulzija." Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2002. https://www.cris.uns.ac.rs/record.jsf?recordId=71467&source=NDLTD&language=en.
Повний текст джерелаAbstract was processed by technology for Optical character recognition (OCR).Maltodextrins, low converted products of starch hydrolysis (dextrose equivalent less than 20), have been subject of various investigations due to their wide application in food industry, cosmetics and pharmaceuticals. They are used in various low energy food emulsions (mayonnaise, salad dressing, spreads) as fat replacer to provide desirable viscosity, texture and sensory fat-like mouthfeel.Viscosity of diluted maltodextrin solutions of different dextrose equivalent and botanical origin were determined by capillary visometer and intrinsic viscosity [q] of each tested maltodextrin was calculated. The values of [q] together with molecular mass M have shown applicability of Staudinger equation, regardless maltodextrin molecules are rather short. The possibility for the determination of DE-values of maltodextrins by viscometric method has been deduced and the equation was calculated for two ranges of DE (5-10/ 10-20).In order to assess behavior of sunflower oil in water emulsions stabilized with food grade emulsifier with addition of maltodextrins in continuous phase in processing (emulsification), as well as end products in application (pouring, spreading) the emulsification dynamics, globule size changes and rheological behavior, as well as, the influence of different factors on dispersion characteristics of such emulsions were studied.Dispersion and viscous properties of emulsions were influenced by certain specific maltodextrin characteristics such as degree of conversion (DE value) i.e. size of maltodextrin molecules. Influence of oil and maltodextrin concentration and partial substitution of oil with equivalent quantity of maltodextrin were investigated too. With increase of oil concentration at the same concentration of maltodextrin in continuous phase, emulsions undergo changes in flow type from shear-thinning to thixotropic and antithixotropic. Antithxotropy induced by shear, was result of formation of network due to two competing factors; linking of oil droplets through maltodextrin molecules as well as orientation of deformed oil droplets and maltodextrin molecules.Addition of maltodextrin, at the same oil concentration and emulsification time, resulted in formation of emulsions with smaller oil droplets.Emulsions with low oil concentration (30%) with maltodextrin in continuous phase were unstable, showing so called creaming effect. This was mainly due to interactions between maltodextrin and emulsifier Tween 80 molecules which took place in continuous phase and on droplet surfaces.
Taudt, Ch, T. Baselt, B. Nelsen, H. Assmann, A. Greiner, E. Koch, and P. Hartmann. "Evaluation of the thermal stability of a low-coherence interferometer for precision surface profilometry." SPIE, 2017. https://tud.qucosa.de/id/qucosa%3A34883.
Повний текст джерелаФлюнт, О. Є. "Залежність параметрів низькочастотної дисперсії від одновісного тиску у кристалах GaSe". Thesis, Сумський державний університет, 2015. http://essuir.sumdu.edu.ua/handle/123456789/40691.
Повний текст джерелаPotier, Clément. "Caractérisation et modélisation des pièges par des mesures de dispersion basse-fréquence dans les technologies HEMT InAIN/GaN pour l'amplification de puissance en gamme millimétrique." Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0033/document.
Повний текст джерелаNowadays, High Electron Mobility Transistors (HEMTs) in Gallium Nitride (GaN) take the lead in power amplification at microwave frequencies. Most of the studies and developments on those HEMTs concern AlGaN/GaN structures but alternative transistors with an InAlN barrier, which reduces the strain in the crystal lattice of the whole structure, are investigated by few laboratories. This thesis presents some advanced studies on the new InAlN/GaN HEMT developed by the III-V Lab, focusing on the trapping phenomena induced by defects inside the crystal structure. A new method for the characterization of these defects, based on low-frequency S-Parameters measurements, is proposed. Furthermore, a non-linear electro thermal model including trapping effects for an InAlN/GaN HEMT is detailed and used to design a MMIC power amplifier for Ka-band applications
Závacký, Jakub. "Technologie úpravy nanočástic pro zlepšení jejich dispergovatelnosti pro využití v cemtových kompzitech." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-432484.
Повний текст джерелаTaudt, Ch, T. Baselt, B. Nelsen, H. Aßmann, A. Greiner, E. Koch, and P. Hartmann. "Two-dimensional low-coherence interferometry for the characterization of nanometer wafer topographies." SPIE, 2016. https://tud.qucosa.de/id/qucosa%3A35105.
Повний текст джерелаGopalakrishnan, Priya. "Effects of the reacting flowfield on combustion processes in a stagnation point reverse flow combustor." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22682.
Повний текст джерелаCommittee Chair: Seitzman, Jerry; Committee Member: Gaeta, Richard; Committee Member: Jagoda, Jeff; Committee Member: Neumeier, Yedidia; Committee Member: Yoda, Minami; Committee Member: Zinn, Ben.
Karam, Hugo Abi. ""Estudo do Jato de Baixos Níveis de Iperó e das Implicações no Transporte de Poluentes no Estado de São Paulo"." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/14/14133/tde-29052003-161622/.
Повний текст джерелаABSTRACT This work investigates the nocturnal Low-Level Jet (LLJ) in Iperó, Brazil, and its role in the pollutant dispersion on the State of São Paulo (SP). Data of four field campaigns in Iperó-SP was used in this investigation. A mesoscale and non-hydrostatic TVM model is also used to simulate the 3D structure of the LLJ, which is a dynamic response to topography and land use. The observational results indicate that the LLJ is frequently found during clear air nights, with a maximum between 8 and 10 m s1, located around 350 m above surface. The LLJ in Iperó is characterized by a directional wind shear, with SE winds near surface and ENE near to the maximum. They occur during the winter and summer, and can modify the diurnal cycle of the mean wind in the first 100 m in the Iperó area. The LLJ are responsible by the nocturnal maximum (21:00 LT) in the mean wind in Iperó. The numerical results indicate the Iperó LLJ is a result of four factors: (1) anabatic circulation in São Paulo sector of the Paraná River Basin; (2) inertial oscillation; (3) nocturnal katabatic circulation and (4) sea breeze. These factors, together, sustain a LLJ with jet core intensity between 5 and 10 m/s, located between 100 and 400 m above surface during the major of nighttime period. The simulated LLJ numerically is found in the west sector in the convergence zone of the anabatic and sea breeze circulations. This convergence flow area appears during the daytime above the more elevated areas in the State of São Paulo, i.e., along mountains aligned parallel to coastline (Serra do Mar and Cantareira). The effects of the LLJ in a pollutant transport were investigated using a Lagrangian Particle Dispersion model coupled to the mesoscale model TVM. The results show that the LLJ increases the horizontal dispersion of the particles released near surface in Iperó and is able to transport the pollutant up to 250 km downwind the source.
Buske, Daniela. "Solução GILTT bidimensional em geometria cartesiana : simulação da dispersão de poluentes na atmosfera." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/13448.
Повний текст джерелаIn the present thesis it is presented a new analytical solution for the transient two- dimensional advection-diffusion equation to simulate the pollutant dispersion in atmosphere. For that, the advection-diffusion equation is solved combining the Laplace transform and the GILTT (Generalized Integral Laplace Transform Technique) techniques. The turbulence closure for Fickian and non-Fickian cases is considered. It is investigated the problem of modeling the pollutant dispersion in strong and weak winds considering, for the case of low wind conditions, the longitudinal diffusion in the advection-diffusion equation. Moreover, it was considered in the model the vertical velocity and its influence was evaluated considering velocities field constant and also generated by means of LES (Large Eddy Simulation), to simulate a more realistic turbulent boundary layer. The results attained by this methodology are validated with experimental results available in literature.
Prochazková, Zdeňka. "Numerické modelování šíření zvuku pomocí diferenčních metod." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231394.
Повний текст джерелаTaudt, Ch, T. Baselt, B. Nelsen, H. Aßmann, A. Greiner, E. Koch, and P. Hartmann. "Measurement of surface topographies in the nm-range for power chip technologies by a modified low-coherence interferometer." SPIE, 2016. https://tud.qucosa.de/id/qucosa%3A35098.
Повний текст джерелаBenvegnù, Agostino. "Trapping and Reliability investigations in GaN-based HEMTs." Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0064/document.
Повний текст джерелаGaN-based high electron mobility transistors (HEMTs) are promising candidates for future microwave equipment, such as new solid state power amplifiers (SSPAs), thanks to their excellent performance. A first demonstration of GaN-MMIC transmitter has been developed and put on board the PROBA-V mission. But this technology still suffers from the trapping phenomena, principally due to lattice defects. Thus, the aim of this research is to investigate the trapping effects and the reliability aspects of the GH50 power transistors for C-band applications. A new trap investigation protocol to obtain a complete overview of trap behavior from DC to radio-frequency operation modes, based on combined pulsed I/V measurements, DC and RF drain current measurements, and low-frequency dispersion measurements, is proposed. Furthermore, a nonlinear electro-thermal AlGaN/GaN model with a new additive thermal-trap model including the dynamic behavior of these trap states and their associated temperature variations is presented, in order to correctly predict the RF performance during real RF operating conditions. Finally, an advanced time-domain methodology is presented in order to investigate the device’s reliability and to determine its safe operating area. This methodology is based on the continual monitoring of the RF waveforms and DC parameters under overdrive conditions in order to assess the degradation of the transistor characteristics in the RF power amplifier
Pathak, Mihir Gaurang. "Periodic flow physics in porous media of regenerative cryocoolers." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49056.
Повний текст джерелаJobic, Yann. "Numerical approach by kinetic methods of transport phenomena in heterogeneous media." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4723/document.
Повний текст джерелаA novel kinetic scheme satisfying an entropy condition is developed, tested and implemented for the simulation of practical problems. The construction of this new entropic scheme is presented. A classical hyperbolic system is approximated by a discrete velocity vector kinetic scheme (with the simplified BGK collisional operator), but applied to an inviscid compressible gas dynamics system with a small Mach number parameter, according to the approach of Carfora and Natalini (2008). The numerical viscosity is controlled, and tends to the physical viscosity of the Navier-Stokes system. The proposed numerical scheme is analyzed and formulated as an explicit finite volume flux vector splitting (FVS) scheme that is very easy to implement. It is close in spirit to Lattice Boltzmann schemes, but it has the advantage to satisfy a discrete entropy inequality under a CFL condition and a subcharacteristic stability condition involving a cell Reynolds number. The new scheme is proved to be second-order accurate in space. We show the efficiency of the method in terms of accuracy and robustness on a variety of classical benchmark tests. Some physical problems have been studied in order to show the usefulness of both schemes. The LB code was successfully used to determine the longitudinal dispersion of metallic foams, with the use of a novel indicator. The entropic code was used to determine the permeability tensor of various porous media, from the Fontainebleau sandstone (low porosity) to a redwood tree sample (high porosity). These results are pretty accurate. Finally, the entropic framework is applied to the advection-diffusion equation as a passive scalar
Butterworth, Sean. "Shape and chemical anisotropic particles in low dielectric constant media." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/shape-and-chemical-anisotropic-particles-in-low-dielectric-constant-media(d8ace7a1-8993-4a6b-a50d-2a2ea71c10f8).html.
Повний текст джерелаJafarpour, Aliakbar. "Ultra Low-Loss and Wideband Photonic Crystal Waveguides for Dense Photonic Integrated Systems." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11598.
Повний текст джерелаKlein, Amélie. "Analyse du profil vertical de l'ozone dans la basse troposphère à Paris." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS192.pdf.
Повний текст джерелаSurface ozone measurements are not sufficient to understand the mechanisms of ozone formation in the lower troposphere. In this study, we have used instruments from the QUALAIR station, located in Paris center, that can measure vertical profiles of ozone, atmospheric dynamics parameters, and integrated contents of NO2 in the lowermost troposphere. First, a statistical analysis, using four years of ground based ozone LIDAR measurements (2011-2014), is done to understand the mechanisms responsible for the vertical gradient and the seasonal cycle of ozone in Paris. Then, in order to better assess the influence of transport on the spatial and temporal evolution of ozone, we focus on the results obtained from an instrumental campaign, organized in Paris, and during which continuous measurements of ozone, wind and turbulence in the atmospheric boundary layer were performed. The results show the impact of the entrainment of the residual layer into the mixed layer on the surface ozone variability in the morning at the local scale. A Lagrangian particle dispersion model (FLEXPART-WRF) is used to better assess the impact of the nocturnal transport of a clean ozone layer via nocturnal low level jets from Paris on the surface ozone evolution at the regional scale. Finally, a one dimensional chemical transport model (PACT 1D) is used to quantify the influence of vertical transport versus photochemistry on the evolution of boundary layer ozone during daytime
Hitchins, Jane. "Dispersion of particles from vehicle emissions." Thesis, Queensland University of Technology, 2001.
Знайти повний текст джерелаLi, Yan. "High-efficiency Blue Phase Liquid Crystal Displays." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5399.
Повний текст джерелаPh.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
Sallet, Marieli, and Marieli Sallet. "Desenvolvimento de um modelo lagrangeano para dispersão de poluentes em condições de vento fraco." Universidade Federal de Pelotas, 2007. http://repositorio.ufpel.edu.br/handle/ri/2183.
Повний текст джерелаCurrently, the search for analytical solutions for the dispersion problems is one of the main research subjects in the pollutant dispersion modeling. These solutions become important due to the intention to obtain dispersion models that generate reliable results in a small computational time, which are of great interest for regulatory air quality applications. Lagrangian particle models are an important and effective tool to simulate the atmospheric dispersion of airborne pollutants. These models are based on the Langevin equation, which is derived from the hypothesis that the velocity is given by the combination between a deterministic term and a stochastic term. In this work is presented a new Lagrangian particle model to simulate the pollutant dispersion in low wind speed conditions. During low wind speed, the diffusion of a pollutant in the planetary boundary layer (PBL) is indefinite and it has been observed that the plume is subject to a great deal of horizontal undulations, which are called plume meandering. The method proposed leads to a stochastic integral equation whose solution has been obtained through the Method of Successive Approximations or Picard s Iteration Method. The integral equation is written in terms of the real and imaginary parts of the complex function before performing the multiplication of the integrating factor, expressed by the Euler formula, inside and outside of the integral solution. To take account the meandering effect, the Frenkiel s Eulerian autocorrelation functions for low wind conditions is included naturally in the model. The new approach has been evaluated through the comparison with experimental data and other different dispersion models. Particularly, the results obtained by the model agree very well with the experimental data, indicating the model represents the dispersion process correctly in low wind speed conditions. It is also possible to verify that the new model results are better than ones obtained by the other models. The analytical feature of the technique and the natural inclusion of the Frenkiel s Eulerian autocorrelation function become the model more accurate than other models.
Atualmente, a busca por soluções analíticas para os problemas de dispersão é um dos principais assuntos de pesquisa na modelagem da dispersão de poluentes. Estas soluções tornam-se importantes devido à intenção de obter modelos de dispersão que geram resultados confiáveis em um tempo computacional pequeno, que são de grande interesse para aplicações no controle da qualidade do ar. Modelos de partícula Lagrangeano são uma ferramenta importante e eficaz para simular a dispersão atmosférica de poluentes do ar. Esses modelos são baseados na equação de Langevin, que é derivada da hipótese que a velocidade é dada por uma combinação entre um termo determinístico e um termo estocástico. Neste trabalho é apresentado um novo modelo de partícula Lagrangeano para simular a dispersão de poluentes em condições de velocidade de vento fraco. Durante a velocidade de vento fraco, a difusão de um poluente na Camada Limite Planetária (CLP) é indefinida e tem sido observado que a pluma está sujeita a grandes ondulações horizontais, que são chamadas meandro do vento. O método proposto leva a uma equação integral estocástica cuja solução é obtida através do Método das Aproximações Sucessivas ou Método Iterativo de Picard. A equação integral é escrita em termos das partes real e imaginária da função complexa antes de realizar a multiplicação do fator integrante, expresso pela fórmula de Euler, dentro e fora da solução integral. Para considerar o efeito do meandro, as funções de autocorrelação Euleriana de Frenkiel para condições de vento fraco são incluídas naturalmente no modelo. A nova aproximação foi avaliada através da comparação com dados experimentais e outros diferentes modelos de dispersão. Particularmente, os resultados obtidos pelo modelo concordam muito bem com os dados experimentais, indicando que o modelo representa o processo de dispersão corretamente em condições de velocidade de vento fraco. Também é possível verificar que os resultados do novo modelo são melhores do que os obtidos pelos outros modelos. A característica analítica da técnica e a inclusão natural da função de autocorrelação Euleriana de Frenkiel tornam o modelo mais exato que os outros modelos.
Lattaud, Cecile. "Synthesis of low density foam shells for inertial confinement fusion experiments." Thesis, Dijon, 2011. http://www.theses.fr/2011DIJOS033/document.
Повний текст джерелаThis work deals with the fabrication process of low density foam shells and the sharp control of their shape (diameter, thickness, density, sphericity, non-concentricity). During this PhD we focused on the non-concentricity criterion which has to be lower than 1%. The shells are synthesized using a microencapsulation process leading to a double emulsion and followed by a thermal polymerization at 60°C. According to the literature, three major parameters, the density of the three phases, the deformations of the shells along the process and the kinetics of the polymerization have a direct influence on the shells non-concentricity. The results obtained showed that when the density gap between the internal water phase and the organic phase increases, the TMPTMA shells non-concentricity improves. A density gap of 0.078 g.cm-3 at 60°C, leads to an average non-concentricity of 2.4% with a yield of shells of 58%. It was also shown that the synthesis process can be considered as reproducible. While using the same internal water phase, equivalent non-concentricity results are obtained using either a straight tube, a tube with areas of constriction or a short wound tube. The time required to fix the shell’s shape is at least 20 minutes with thermal polymerization. So, it seems that the time spent by the shells inside the rotating flask allows the centering of the internal water phase inside the organic phase, whatever the circulation process used. In order to get higher polymerization rates and to avoid destabilization phenomena, we then focused our study on photopolymerization. When the synthesis is performed using a UV lamp with an efficient light intensity, the shells have a slightly higher thickness than the shells synthesized by thermal polymerization. Moreover, a really higher yield, around 80%, is achieved with UV polymerization. However, the average non-concentricity of the shells synthesized lays around 20%, which is really high compared to the 2.4% average non-concentricity obtained with thermal polymerization. It would be interesting to expose the shells to UV light at different times after collection in order to study the influence of the agitation time on the shells non-concentricity
Allain, Florent. "Evaluation of the Classical Reaction Engineering models in terms of mass transport and reaction rate distribution for low tube-to-particle diameter ratio beds." Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-theses/374.
Повний текст джерелаAzim, Riasat. "Low-Storage Hybrid MacCormack-type Schemes with High Order Temporal Accuracy for Computational Aeroacoustics." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1515720270119389.
Повний текст джерелаLattaud, Cécile. "Synthesis of low density foam shells for inertial confinement fusion experiments." Phd thesis, Université de Bourgogne, 2011. http://tel.archives-ouvertes.fr/tel-00692058.
Повний текст джерелаFerreira, Júnior Elmo de Sena 1989. "Gas jet modeling using large eddy simulation in a low momentum cfd code = Modelagem de um jato de gás usando simulações das grandes escalas em um código cfd de baixo momento." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266050.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-26T16:12:11Z (GMT). No. of bitstreams: 1 FerreiraJunior_ElmodeSena_M.pdf: 18188081 bytes, checksum: 2b445e8828a2a2b90c9a27c3379a7d74 (MD5) Previous issue date: 2015
Resumo: A simulação numérica é de grande importância em diversas áreas da engenharia, tais como otimização e manutenção de processo químico, bem como na indústria do petróleo e segurança do processo. O Fire Dynamics Simulator (FDS) é um código de Fluidodinâmica Computacional com base na simulação das grandes escalas. Este foi desenvolvido pelo Instituto Nacional de Padrões e Tecnologia (NIST). O código FDS foi originalmente projetado para modelar baixo fluxo de velocidade comumente encontrados em cenários de incêndio. Assim, o FDS não é adequado para simulação de casos onde o número de Mach é elevado. Para superar esta limitação, este trabalho propõe um novo modelo dedicado às características próximas da saída do jato a fim de permitir o FDS simular cenários de jatos e dispersão de gás. A abordagem também reduz significativamente o tempo da simulação computacional. A ferramenta proposta é uma alternativa livre e confiável para a modelagem de dispersão de gás. Os resultados são amplamente discutidas e um estudo de caso de uma plataforma é apresentado. A comparação com os resultados experimentais, bem como um pacote CFD comercial mostram boa concordância
Abstract: The numerical simulation is of great importance in various areas of engineering such as optimization and maintenance of chemical process, petroleum industry and process safety. The Fire Dynamics Simulator (FDS) is a Computational Fluid Dynamics (CFD) code based on Large Eddy Simulation (LES) modeling and developed by National Institute of Standards and Technology (NIST). FDS code was originally designed to model low speed flow commonly found in fire scenarios. Hence, FDS is not suitable for modeling high Mach number cases. To overcome this limitation this work proposes a novel model dedicated to the near field jet characteristics in order to enable FDS to simulate jet scenarios and gas dispersion. The approach also reduces the computational time significantly as far as turbulent jet flows are concerned. The proposed tool is a free and reliable alternative for gas dispersion modeling. Results are extensively discussed and case study for a typical offshore site is presented. Comparison with experimental results as well as commercial CFD package show good agreement
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
Patwari, Neal. "Measured and Modeled Time and Angle Dispersion Characteristics of the 1.8 GHz Peer-to-Peer Radio Channel." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/32201.
Повний текст джерелаMaster of Science
Suyitno, Budhi-Muliawan. "Etude du comportement en fatigue d'aciers à dispersoïdes." Poitiers, 1988. http://www.theses.fr/1988POIT2342.
Повний текст джерелаShiran, Vahid. "Design and optimization of terahertz waveguides with low loss and dispersion." Thesis, 2020. http://hdl.handle.net/1828/12090.
Повний текст джерелаGraduate