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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Les territoires aéroportuaires comme catalyseurs de la connaissance et source d’innovation pour les métropoles mondiales : de l'airport city à l'aerotropolis ? / Airport territories as catalyist of knowledge and innovation for world metropolis : from Airport city to aerotropolis ?

Grangé, Jacques 19 September 2018 (has links)
Le développement du trafic aérien international est une composante majeure de la croissance des échanges internationaux intervenue depuis la seconde guerre mondiale. La traduction terrestre en est le développement des plateformes aéroportuaires. Avec les dérégulations intervenues dans les années 1990 les hubs sont des éléments majeurs de l’espace européen. Ils ont généré des territoires aéroportuaires allant au-delà des limites administratives et domaniales des aéroports ; ceux-ci sont des espaces importants de l’économie de la connaissance et de l’innovation. A ce titre, ils sont des polarités métropolitaines majeures. Nous en avons choisi trois majeures situées sur deux continents : Paris- Charles de Gaulle, Amsterdam- Schiphol et Seoul- Incheon. En raison de leur accessibilité multimodale synchrone, ces aéroports sont parties prenantes de territoires aéroportuaires importants et multifonctionnels. Ils participent sous de formes et des degrés divers à l’économie de la connaissance et de l’innovation et en particulier à ses circulations. / The development of international air traffic is a major component of the international exchanges occurred since the Second World War. The terrestrial translation is the development of airport. With the deregulations occurred in the years the 1990, hubs are major elements of European space. They generated airport territories going beyond the administrative and domanial limits of the airports; those are important spaces of the knowledge and innovation economy. For this reason, they are major metropolitan polarities. We chose three major located out of two continents: Paris Charles de Gaulle, Amsterdam Schiphol and Seoul Incheon... Because of their synchronous multimode accessibility, these airports are recipients of important and multipurpose airport territories. They take part in various forms and degrees in the knowledge and innovation economy and in particular in its circulations
52

Quantum optics with structured light / Optique quantique avec lumière structurée

Chille, Vanessa 23 September 2016 (has links)
La présente thèse a pour objectif d'analyser la lumière structurée non-classique et ses caractéristiques. L'optique quantique et la lumière structurée sont deux sujets qui font l'objet d'examens nombreux. Ils sont néanmoins rarement examinés en combinaison. Les propriétés quantiques de la lumière structurée sont moins bien étudiées qu'ils devraient l'être. Par la lumière structurée nous entendons les champs lumineux qui montrent une structure transverse complexe de l'intensité, la phase ou la polarisation. Nous voulons lier les deux sujets de l'optique quantique et la lumière structurée dans la présente thèse. Dans ce but, nous générons expérimentalement des champs lumineux structurés non-classiques. En particulier, nous réalisons une expérience qui permet de générer des faisceaux vectoriels vectoriels - c'est-à-dire des faisceaux lumineux dont l'état de polarisation présente une structure transverse complexe - qui montrent une réduction du bruit quantique. En outre, nous étudions théoriquement les propriétés spatiales de faisceaux lumineux, ainsi que leur bruit. Plus spécifiquement, nous analysons l'incertitude quantique dans la largeur d'un faisceau lumineux. Pour prouver la faisabilité de la vérification expérimentales de nos résultats théoriques, nous réalisons des simulations pour la mesure de paramètres spatiales utilisant un détecteur mulitpixels. / This thesis aims at learning more about nonclassical structured light. Quantum optics and structured light are two topics that are subject to countless scientific examinations. However, they are very rarely combined and the quantum properties of structured light are not as thoroughly studied as they deserve. By structured light, we mean any light fields with complex transverse distributions of intensity, phase or polarization. We want to link the topics of quantum optics and structured light in this thesis. For this purpose, we experimentally generate particular nonclassical structured light fields. In particular, we construct an experimental setup that enables us, in principle, to produce arbitrary amplitude squeezed vector beams, i.e. light beams with a complex transverse structure of the state of polarization. Furthermore, we analyze spatial properties of light beams, and their quantum noise theoretically. We specifically perform theoretical examinations of the quantum noise in the width of a light beam. To show the feasibility of an experimental verification of our theoretical results, we conduct simulations for the measurement of spatial parameters of a beam's cross-section by a multipixel detector.
53

Soustracteur de photons uniques pour états quantiques multimode dans le domaine spectral / A single-photon subtractor for spectrally multimode quantum states

Jacquard, Clément 20 January 2017 (has links)
Dans le cadre de cette thèse, nous avons construit et caractérisé un soustracteur de photons uniques pour l'ingénierie d'états quantiques de la lumière. Le but étant de réaliser une soustraction de photon pure et spectralement sélective sur une ressource multimode dans le domaine spectral. Ce soustracteur repose sur une interaction paramétrique de somme de fréquence entre un faisceau signal et un faisceau de contrôle au sein d'un milieu non-linéaire. Le spectre du faisceau de contrôle est mis en forme à l'aide d'un procédé de mise en forme d'impulsion. Le photon convertit est filtré et détecté grâce à détecteur de photon unique. Le soustracteur est donc la combinaison de tous ces éléments successifs. Nous avons développé un cadre théorique décrivant la soustraction multimode de photons uniques et montré qu'elle peut être décrite, peu importe l'implémentation, par une matrice de soustraction dans une base de modes. Grâce à ce formalisme, nous avons montré que le processus pouvait être caractérisé sans mesurer le signal transformé mais simplement en lui substituant un faisceau sonde dont les impulsions sont aussi mises en forme. Nous avons réalisé une tomographie du processus au niveau du photon unique pour une large gamme de faisceaux de contrôle différents. Nos résultats sont correctement décrits par la théorie développée et démontre la pureté du processus ainsi que l'agilité de la technique employée. / During this thesis, we have built and characterized a single-photon subtractor to engineer the quantum states of light. The aim is to perform a pure and spectrally selective photon subtraction on a multimode resource in the spectral domain. This subtractor consists in a parametric sum-frequency interaction between a signal beam and a control beam within a non-linear medium. The optical spectrum of the control beam is shaped using ultrafast pulse shaping. The up-converted photon is filtered and detected by a single-photon detector. The subtractor is therefore the combination of all these successive elements. We have developed a theoretical framework to describe the multimode subtraction of a single photon and showed that it can be summed up by a subtraction matrix in a modal basis independently of the physical implementation. Thanks to this formalism, we have shown that the process can be characterized without measuring the transformed signal beam but simply by using a probe beam whose pulses are also shaped. We carried out a process tomography at the single-photon level for a wide range of different control beams. Our results are correctly described by the theory we developed and demonstrates the purity of the process as well as the agility of the technique we used.
54

Performance Characterization of Silicon-On-Insulator (SOI) Corner Turning and Multimode Interference Devices

Zheng, Qi January 2012 (has links)
Silicon-on-insulator (SOI) technology has become increasingly attractive because of the strong light confinement, which significantly reduces the footprint of the photonic components, and the possibility of monolithically integrating advanced photonic waveguide circuits with complex electronic circuits, which may reduce the cost of photonic integrated circuits by mass production. This thesis is dedicated to numerical simulation and experimental performance measurement of passive SOI waveguide devices. The thesis consists of two main parts. In the first part, SOI curved waveguide and corner turning mirror are studied. Propagation losses of the SOI waveguide devices are accurately measured using a Fabry-Perot interference method. Our measurements verify that the SOI corner turning mirror structures can not only significantly reduce the footprint size, but also reduce the access loss by replacing the curved sections in any SOI planar lightwave circuit systems. In the second part, an optical 90o hybrid based on 4 × 4 multimode interference (MMI) coupler is studied. Its quadrature phase behavior is verified by both numerical simulations and experimental measurements.
55

Optovláknový sensor na principu vícemódové interference / Fiber-optic sensor based on multi-mode interference

Hedl, Michal January 2020 (has links)
This diploma thesis is focused on measurement of the physical quantities by fiber optic sensors based on multimode interference. The objective is to evaluate the appropriate method of signal provided by the spectrum analyzer. Firstly, a review of optics, optical phenomena and fibers is performed. The basic theory necessary for the realization of measurements and the principal of fiber optic sensors and SMS (singlemode–multimode–singlemode) structures are discussed. Finally, the automated measuring workplace for absorption spectrum measurement is created and described. Given data are finally evaluated by an artificial neural network and a sensor concept for practical utilization is designed.
56

Characterization of a Red Multimode Vertical-Cavity Surface-Emitting Laser for Intrinsic Parameters

Wagstaff, Jonathan 07 1900 (has links)
Compared to single-mode VCSELs, multimode VCSELs have not received much attention in models and characterizations for functional parameters, despite making up the majority of commercially available VCSELs [1]. In particular, the extraction of the linewidth enhancement factor for multimode VCSELs has been overlooked, likely due to difficulties in measurement. Additionally, multimode models for VCSELs have, until recently, omitted spectral characteristics such as linewidth [2]. This is the first work to report a measured linewidth enhancement factor value (lower bound) for a multimode VCSEL. A characterization for the functional parameters of a red multimode vertical-cavity surface-emitting laser (VCSEL) is shown herein. The extracted values form a complete working set of parameters for the laser rate equations. The techniques employed for extracting values include frequency responses, power versus current fittings, and optical spectral measurements. From the frequency responses at various bias currents, the relaxation oscillation frequency and damping factor are found. The power versus current curve is fitted to find parameters including the modal spontaneous emission rate and carrier density at threshold. The spectral measurements are used for evaluating the linewidth enhancement factor (LEF) also known as the alpha factor or Henry factor. These 5 methods have been applied previously to characterizing single-mode VCSELs [3]–[5]. The experimentally extracted parameters herein are important for creating accurate models and simulations for multimode VCSELs. Improved multimode VCSEL models are necessary for improving optical communication, especially for short-range optical interconnects [2]. The measured parameters for the characterized VCSEL are comparable to similar single-mode VCSELs characterized in other works. This is promising because multi-mode VCSELs have higher output power than their single-mode counterparts, thus these results may aid in improving short-range optical interconnects.
57

Nonlinear Dynamics of Tapping Mode Atomic Force Microscopy

Bahrami, Arash 05 September 2012 (has links)
A mathematical model is developed to investigate the grazing dynamics of tapping mode atomic force microscopes (AFM) subjected to a base harmonic excitation. The nonlinear dynamics of the AFM microcantilever are studied in both of the monostable and bistable phases with the microcantilever tip being, respectively, located in the monostable and bistable regions of the static bifurcation diagram in the reference configuration. Free-vibration responses of the AFM probes, including the microcantilever natural frequencies and mode shapes, are determined. It is found that, for the parameters used in a practical operation of an AFM, the natural frequencies and mode shapes of the AFM microcantilever are almost the same as those of a free-end microcantilever with the same geometry and made of an identical material. A multimode Galerkin approximation is utilized to discretize the nonlinear partial-differential equation of motion and associated boundary conditions governing the cantilever response and obtain a set of nonlinearly coupled ordinary-differential equations (ODE) governing the time evolution of the system dynamics. The corresponding nonlinear ODE set is then solved using numerical integration schemes. A comprehensive numerical analysis is performed for a wide range of the excitation amplitude and frequency. The tip oscillations are examined using nonlinear dynamic tools through several examples. The non-smoothness in the tip/sample interaction model is treated rigorously. A higher-mode Galerkin analysis indicates that period doubling bifurcations and chaotic vibrations are possible in tapping mode microscopy for certain operating parameters. It is also found that a single-mode Galerkin approximation, which accurately predicts the tip nonlinear responses far from the sample, is not adequate for predicting all of the nonlinear phenomena exhibited by an AFM, such as grazing bifurcations, and leads to both quantitative and qualitative errors. A point-mass model is also developed based on the single-mode Galerkin procedure to compare with the present distributed-parameter model. In addition, a reduced-order model based on a differential quadrature method (DQM) is employed to explore the dynamics of the AFM probe in the bistable phase where the multimode Galerkin procedure is computationally expensive. We found that the DQM with a few grid points accurately predicts the static bifurcation diagram. Moreover, we found that the DQM is capable of precise prediction of the lowest natural frequencies of the microcantilever with only a few grid points. For the higher natural frequencies, however, a large number of grid points is required. We also found that the natural frequencies and mode shapes of the microcantilever about non-contact equilibrium positions are almost the same as those of the free-end microcantilever. On the other hand, free-vibration responses of the microcantilever about contact equilibrium positions are quite different from those of the free-end microcantilever. Moreover, we used the DQM to discretize the partial-differential equation governing the microcantilever motion and a finite-difference method (FDM) to calculate limit-cycle responses of the AFM tip. It is shown that a combination of the DQM and FDM applied, respectively, to discretize the spatial and temporal derivatives provides an efficient, accurate procedure to address the complicated dynamic behavior exhibited by the AFM probe. The procedure was, therefore, utilized to study the response of the microcantilever to a base harmonic excitation through several numerical examples. We found that the dynamics of the AFM probe in the bistable region is totally different from those in the monostable region. / Ph. D.
58

Interference and correlation effects in multimode quantum systems. Multimode systems.

Dedes, Christos January 2009 (has links)
The purpose of this thesis is the theoretical study of interference and correlation effects in multimode and continuum mode quantum systems. We are concerned with interference effects in multiport devices which in a sense are generalised Mach-Zehnder interferometers. It is shown how these multimode devices can be employed for the study of negative result and interaction free measurements. Interference and coherence effects are also studied in relation to the radiation fields generated by atoms through the process of spontaneous emission. Besides first order interference, higher order coherence effects are investigated with the aid of Glauber's photodetection theory and it is found that detectors that lie in spacelike regions may display nonclassical correlations under certain conditions. It is well known that the vanishing of field commutators between regions that cannot be connected by subluminal signals reflects the locality of quantum field theory. But is it possible that these spacelike regions exhibit correlations that violate Bell type inequalities? This is the main question and principal concern of the thesis and the answer is affirmative, nonclassical correlations between spacelike regions are indeed possible. A scheme of four detectors that lie in spacelike points was also studied. In this case we do not consider the radiation field but a free scalar field in vacuum state. Nevertheless the virtual quanta of this field may induce nonclassical correlations if the intervals between the detectors are spacelike but small enough. The fundamental reason for this fact is the nonvanishing of the Feynman propagator outside the light cone. Since this propagator is decaying expotentially with the distance it is demonstrated that for large spacelike intervals field correlations obey classical inequalities. We should also note that different inertial observers will agree on the violation or not of these inequalities since the results are manifestly Lorentz invariant.
59

Characterization of High-Aspect Ratio, Thin Film Silicon Carbide Diaphragms Using Multimode, Resonance Frequency Analysis

Barnes, Andrew Charles 06 February 2015 (has links)
No description available.
60

ELECTRICAL EQUALIZATION FOR MULTIMODE FIBER SYSTEMS

Liu, Yizhou 11 January 2017 (has links)
No description available.

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