Le but de cette thèse est d'étudier d'une façon expérimentale et théorique le comportement synchrone d'un groupe d'oscillateurs contrôlés par la lumière (LCOs). Ces LCOs sont très simples du point de vue électronique et ont la propriété d'imiter le comportement des lucioles puisqu'ils interagissent par des impulsions de lumière. En même temps, les LCOs sont une bonne approche pour étudier d'autres systèmes qui agissent comme des oscillateurs d'intégration et de tir car un LCO est un oscillateur de relaxation à deux échelles de temps : un long processus de charge alterné avec un très court processus de décharge. Une série d'expériences a été menée pour pouvoir comprendre le processus de synchronisation des LCOs. Nous avons trouvé que l'acquisition de la synchronisation est due aux effets de la perturbation à savoir: le raccourcissement de la charge et l'allongement de la décharge. Les mesures expérimentales ainsi que la physique liée aux LCOs nous ont permis de formuler un modèle qui a été utilisé pour trouver d'une façon analytique la courbe de réponse de phase (PRC) qui caractérise un LCO. Le modèle a ensuite été validé en comparant les résultats expérimentaux et théoriques. Le modèle reproduit même, le phénomène de bifurcation qui apparaît lorsque trois LCOs sont couplés et disposés en ligne : deux états stables différents apparaissent selon les conditions initiales. L'accord trouvé entre théorie et expérience nous permet d'utiliser le modèle pour étudier d'autres situations qui ne sont pas facilement abordables du point de vue expérimental. Nous avons étudié analytiquement deux LCOs identiques couplés. Même pour ce cas idéal, nous étions obligés de faire des simplifications pour pouvoir trouver des solutions exactes. On a trouvé pour ce système deux états possibles qui dépendent des conditions initiales, la synchronisation (stable) et l'anti-synchronisation (instable). Nous avons également montré que le temps de synchronisation augmente avec la distance entre LCOs. La construction des langues d'Arnold (régions de synchronisation) nous a permis de distinguer des régions de synchronisation pure d'ordre n:m et des régions de superposition synchronisation--modulation. Nous avons travaillé numériquement avec des systèmes de LCOs affectés de bruits uniforme et Gaussien. Le comportement synchrone de ce système a été caractérisé en utilisant des paramètres statistiques simples tels que la moyenne de la différence de phase linéaire et la variance de la différence de phase cyclique. Nous avons démontré que le bruit, bien qu'il puisse perturber la synchronisation, peut aussi la favoriser entre deux LCOs qui ne se synchroniseraient pas en conditions normales, surtout quand le bruit est Gaussien et que les variances du bruit ne sont pas égales. Nous avons étudié en termes statistiques la synchronisation de LCOs couplés localement et arrangés en ligne, en anneau et en réseau. Nous avons montré que la synchronisation totale se produit plus facilement pour des LCOs disposés en anneau. Concernant le temps de synchronisation, il est imprédictible. Les résultats analytiques et numériques suggèrent que la synchronisation totale est le phénomène le plus probable quand le nombre d'oscillateurs n'est pas très grand. Finalement, nous avons étudié des LCOs statiques et mobiles couplés globalement. Dans les deux cas, nous avons trouvé que la synchronisation est moins probable quand le nombre d'oscillateurs augmente. Pour la condition statique, en considérant un couplage du type champ moyen, nous avons observé que le temps de synchronisation diminue avec le nombre de LCOs. Cependant, pour la situation plus réaliste dans laquelle l'interaction entre LCOs dépend de la distance les séparant, le temps de synchronisation devient à nouveau imprédictible. Enfin, nous avons étudié l'influence de la mobilité sur la synchronisation, problème qui est important en biologie et en robotique. Notre système, de par ses caractéristiques et sa base expérimentale, est beaucoup plus proche de la réalité que ceux considérés d'habitude dans la littérature. Les résultats obtenus peuvent s'appliquer à des systèmes biologiques (lucioles, cellules cardiaques, neurones, …), mais également à la robotique, où la communication à longue portée par la lumière et l'émergence de patterns de synchronisation pourraient être très utiles dans le but d'effectuer des tâches spécifiques.

The research described in this dissertation is the first evaluation of two-dimensional charge coupled devices (CCDs) for low light level analytical spectroscopy. The electro-optical properties of several unique two-dimensional CCDs are evaluated, including quantum efficiency, detector read noise, linearity, dynamic range, dark current, and blooming. Theoretical models describing the sensitivity and dynamic range of CCDs on a single detector element basis are developed. Based on this model and the characteristics of a CCD detector system built for this research, it is shown that a single detector element of a CCD has comparable or superior sensitivity than the most sensitive single channel detectors. The results of the CCD detector system applied to fluorescence, emission, absorption, and time and spatially resolved spectroscopies are presented. The charge binning readout mode, which combines charge packets from several detector elements into a single charge packet, is critically evaluated for increasing the sensitivity and dynamic range of spectroscopic measurements. Equations describing the sensitivity and dynamic range enhancement achieved through charge binning are derived and experimentally verified in atomic emission and molecular fluorescence spectroscopies. The results of operating the CCD in two specialized readout modes developed in this research termed high-speed framing and spectral framing are presented. High speed framing allows the CCD to rapidly acquire two-dimensional images with high sensitivity. The spectral framing readout mode enables the CCD to record time-resolved spectra at a rate of approximately one spectra every two microseconds with great sensitivity. The design and evaluation of a CCD based molecular fluorescence spectrograph using a mercury pen lamp excitation source is described. The limit of detection for anthracene is 1 x 10 ⁻¹²M and is superior to the results obtained by fluorometers employing laser sources and photomultiplier detection. The design and evaluation of a spatially resolving spectrograph for absorbance spectroscopy of optically dense films is presented. The measurement of the absorption spectra of spatially heterogeneous metal-phthalocyanine thin-film electrodes with peak absorbances greater than five absorbance units is described.

This dissertation deals with the measurement of Modulation Transfer Function (MTF) and spatial noise in infrared CCD's. A new method for the measurement of MTF is presented, which uses the phenomenon of laser speckle. The instrument constructed has the advantages that it does not require components of high optical or mechanical quality, and it does not require precise alignment. There is only one moving part in the system. The results of this method are compared with results obtained from an interferometric technique and from an impulse response technique, and found to be in close agreement. The characterization of spatially-dependent noise is pursued via the formalism of Detective Quantum Efficiency and also via a two dimensional generalization of the classical representation for information capacity. Suggestions for improving the performance of the array as a signal processor are drawn from these considerations. Test results are presented for a 64 by 32 element infrared CCD of Schottky barrier construction.

No description available.

No description available.

A truss spar, named as Horn Mountain, was deployed in the Gulf of Mexico in 1,650 m of water, approximately 150 km southeast of New Orleans in June 2002. Horn Mountain is operated by British Petroleum (B.P.). Extensive field measurements were made using an integrated marine monitoring system attached to the truss spar. In this study, dynamic analysis of the truss spar interacting with its mooring and riser system was performed using a time-domain numerical code, known as ‘COUPLE’. The simulated results were then compared with the corresponding field measurements made during Hurricane Isidore. During the numerical study, various hydrodynamic parameters which were crucial to the accuracy of predicting the global motions of the truss spar and tensions in mooring lines and risers were scrutinized, such as the drag and added-mass coefficients of heave plates, hard tank and truss beams. Satisfactory agreement between the simulation and corresponding measurements was reached, indicating that the numerical code, COUPLE, can be used to conduct the time-domain analysis of a truss spar interacting with its mooring and riser system under severe storm impact. A comparative study was also conducted to analyze the significance of interaction of risers with the hull structure. Three different cases of coupled analysis are simulated, namely (i) coupled analysis of truss spar interacting with mooring lines, (ii) coupled analysis of truss spar interacting with the mooring lines and the steel catenary risers, (iii) coupled analysis of truss spar interacting with the mooring lines, the steel catenary risers and top tension risers. Major statistical parameters of the global motions of the truss spar and the mooring line tensions for the three cases are compared with the field measurements.

Reservoir geomechanics is a production induced phenomena that is experienced in large number of fields around the world. Hydrocarbon production changes the pore pressure which in turn alters the in-situ stress state. For reservoirs that are either stress sensitive or where rock is soft and unconsolidated, stresses have appreciable effect on rock properties like porosity and permeability. Anisotropic and isotropic permeability changes affect flow direction and movement of flood front thereby influencing well performance and reservoir productivity. Coupling of geomechanical calculation with multi-phase flow calculation is needed to make prudent predictions about the reservoir production and recovery. The post processing tools provided with the simulators cannot monitor flood front movement and fail to capture important information like flow directionality and dominant phase in a flow. Geomechanical simulation is combined with streamline tracing to aid in better understanding of the reservoir dynamics through visualization of flow patterns in the reservoir. Streamline tracing is a proved reservoir engineering tool that is widely used by industry experts to capture information on flood movement, injector-producer relations and swept area. In the present research, we have incorporated total velocity streamlines and phase streamlines for coupled geomechanical simulation and compared the results with streamline tracing for conventional reservoir simulator to explain geomechanics behavior on reservoir flow processes in a more detailed and appealing manner. Industry standard simulators are used for coupled geomechanical simulation and conventional simulation and streamline tracing has been done through in-house tracing code. The research demonstrates the benefits and power of streamline tracing in visualizing flow patterns through work on two cases; first, a synthetic case for studying water injection in a five spot pattern and second, a SPE 9th comparative study. The research gives encouraging results by showing how geomechanics influences reservoir flow paths and reservoir dynamics through visualization of flow. The streamlines captures flow directionality, information regarding appearance and disappearance of gas phase and the connectivity between injector and producer.

A truss spar, named as Horn Mountain, was deployed in the Gulf of Mexico in 1,650 m of water, approximately 150 km southeast of New Orleans in June 2002. Horn Mountain is operated by British Petroleum (B.P.). Extensive field measurements were made using an integrated marine monitoring system attached to the truss spar. In this study, dynamic analysis of the truss spar interacting with its mooring and riser system was performed using a time-domain numerical code, known as ‘COUPLE’. The simulated results were then compared with the corresponding field measurements made during Hurricane Isidore. During the numerical study, various hydrodynamic parameters which were crucial to the accuracy of predicting the global motions of the truss spar and tensions in mooring lines and risers were scrutinized, such as the drag and added-mass coefficients of heave plates, hard tank and truss beams. Satisfactory agreement between the simulation and corresponding measurements was reached, indicating that the numerical code, COUPLE, can be used to conduct the time-domain analysis of a truss spar interacting with its mooring and riser system under severe storm impact. A comparative study was also conducted to analyze the significance of interaction of risers with the hull structure. Three different cases of coupled analysis are simulated, namely (i) coupled analysis of truss spar interacting with mooring lines, (ii) coupled analysis of truss spar interacting with the mooring lines and the steel catenary risers, (iii) coupled analysis of truss spar interacting with the mooring lines, the steel catenary risers and top tension risers. Major statistical parameters of the global motions of the truss spar and the mooring line tensions for the three cases are compared with the field measurements.

No description available.

No description available.