HIGH-FREQUENCY MOTION RESIDUALS IN MULTIBEAM ECHOSOUNDER DATA: ANALYSIS AND ESTIMATION

Advances in multibeam sonar mapping and data visualization have increasingly brought to light the subtle integration errors remaining in bathymetric datasets. Traditional field calibration procedures, such as the patch test, just account for static orientation bias and sonar-to-position latency. This, however, ignores the generally subtler integration problems that generate time-varying depth errors. Such dynamic depth errors are the result of an unknown offset in one or more of orientation, space, sound speed or time between the sonar and ancillary sensors. Such errors are systematic, and thus should be predictable, based on their relationship between the input data and integrated output. A first attempt at addressing this problem utilized correlations between motion and temporally smoothed, ping-averaged residuals. The known limitations of that approach, however, included only being able to estimate the dominant integration error, imperfectly accounting for irregularly spaced sounding distribution and only working in shallow water. This thesis presents a new and improved means of considering the dynamics of the integration error signatures which can address multiple issues simultaneously, better account for along-track sounding distribution, and is not restricted to shallow water geometry. The motion-driven signatures of six common errors are simultaneously identified. This is achieved through individually considering each sounding’s input-error relationship along extended sections of a single swath corridor. Such an approach provides a means of underway system optimization using nothing more than the bathymetry of typical seafloors acquired during transit. Initial results of the new algorithm are presented using data generated from a simulator, with known inputs and integration errors, to test the efficacy of the method. Results indicate that successful estimation requires conditions of significant vessel motion over periods of a few tens of seconds as well as smooth, gently rolling bathymetry along the equivalent spatial extent covered by the moving survey platform

Factors in older adult\u27s resistance to substance abuse treatment for prescription and over-the-counter-medication

The purpose of this study was to determine the factors that cause resistance in older adults to participation substance abuse (prescription drugs) treatment programs

Generalized diffusion problems in a conical domain, part II

After different variables and functions changes, the generalized dispersal problem, recalled in (1) below and considered in part I, see [14], leads us to invert a sum of linear operators in a suitable Banach space, see (2) below. The essential result of this second part lies in the complete study of this sum using the two well-known strategies: the one of Da Prato-Grisvard [4] and the one of Dore-Venni [6]

Generalized diffusion problems in a conical domain, part I

The purpose of this article (composed of two parts) is the study of the generalized dispersal operator of a reaction-diffusion equation in $L^p$-spaces set in the finite conical domain $S_{\omega,\rho}$ of angle $\omega>0$ and radius $\rho>0$ in $\mathbb{R}^2$. This first part is devoted to the behaviour of the solution near the top of the cone which is completely described in the weighted Sobolev space $W^{4,p}_{3-\frac{1}{p}}(S_{\omega,\rho})$, see Theorem 2.2

Dispersion Characterization in Single-Mode Optical Fibers for Supercontinuum Generation Supporting Few-Cycle Pulses

Dans les dernières décennies, le domaine de la photonique ultra rapide a connu de nombreuses avancées. Cela a été motivé du côté de l’industrie par l’augmentation de la bande passante et l’utilisation des fibres optiques pour transmettre l’information et du côté fondamental par le fait que la génération d’impulsions lumineuses courtes donne accès à un instrument d’exploration des dynamiques fondamentales de la matière. La propagation d’impulsions ultra courtes est accompagnée par un élargissement spectral induit par des effets d’optique non linéaire dus à l’intensité importante de l’impulsion. La géométrie des fibres optiques permet la propagation confinée de la lumière pour une distance supérieure à la longueur de diffraction caractéristique. Cela fait des fibres monomodes des candidates très attractives pour la génération d’impulsions à l’aide d’effets non linéaires. La propagation de telles impulsions est fortement influencée par les propriétés dispersives des matériaux et du guide d’onde et pousse l’étude des caractéristiques dispersives des fibres mono-modes à travers une large bande spectrale. L’objectif principal du projet est de caractériser la dispersion de fibres optiques avec une extrême précision sur une large région spectrale. A cause de la dispersion induite par la géométrie du guide d’onde, utiliser l’équation de Sellmeier ne suffit pas pour décrire précisément la dispersion dans une fibre optique. Il est donc nécessaire de construire un montage optique. Un interféromètre de Mach-Zehnder qui contient la fibre sous étude dans un de ses bras et une ligne à délai dans l’autre est parfait pour cette application. L’étude des interférences à des longueurs d’onde différentes permet d’obtenir toute l’information nécessaire à l’extraction de la dispersion, comme le montre le chapitre 3. L’interféromètre est un système sensible, le ratio signal sur bruit doit être optimisé à la fois lors de l’acquisition du signal et lors de son traitement subséquent. Nous appliquons une transformée de Hilbert pour récupérer l’enveloppe du signal oscillant, comme le montre le chapitre 4. Notre montage est capable de mesurer et d’analyser la dispersion d’une fibre optique entre les longueurs d’onde de 1150 et 2600 nm. Il est compact et portable (en omettant la source de lumière) avec la possibilité de changer la fibre à étudier. Obtenir les caractéristiques dispersives d’une fibre optique hautement non linéaire permet de simuler la propagation d’une impulsion lumineuse courte (60 fs) dans celle ci. En utilisant un programme Python pour modéliser à la fois les non-linéarités et les effets dispersifs de la fibre optique, on obtient la forme temporelle et spectrale de l’impulsion à la sortie de la fibre.----------Abstract Within the last few years, many advances have been made in the field of ultrafast photonics. On the technology side, this interest is motivated by increasing bandwidth requirements in telecommunications and the use of fiber optics to transmit information. On the fundamental side, production of short pulses provides an instrument for investigating fundamental dynamics underlying interacting internal degrees of freedom in matter. The propagation of ultrashort pulses often requires spectral broadening via optical nonlinear processes accessed through the high peak intensity of the pulse. Optical fiber geometry allows for propagation of localized light through distances much longer than the characteristic diffraction length. As a result, single-mode optical fibers are very attractive candidates as a nonlinear medium for the production of ultrashort pulses. Propagation of short pulses is also strongly influenced by the dispersion properties of the medium and thus motivates the study of dispersion properties of single-mode fibers across a wide spectral band. The primary objective of this project is to characterize the dispersion in optical fibers with extreme precision over a large region of spectral bandwidth. Because of the dispersion induced by the waveguide geometry, Sellmeier’s equations do not accurately describe the dispersive properties of a fiber. Building a characterization setup is then necessary. An unbalanced Mach-Zehnder interferometer with the fiber under measurement on one arm and a delay stage on the other is perfect in this case. Generating interferences with different input wavelengths gives all the information to compute the fiber dispersion as shown in chapter 3. As interferometers are very sensitive, the signal to noise ratio can be improved by optimizing the electronics on the hardware side, and by using a Hilbert transform to retrieve the envelope of a signal on the processing side, as shown in chapter 4. The setup built in this project is able to measure and analyse the dispersion of an optical fiber between the wavelengths of 1150 nm and 2600 nm. It is both compact and movable (minus the light source) with the possibility to change the fiber to measure. Computing dispersion allows to simulate the propagation of an ultrashort pulse (60 fs) in a highly nonlinear fiber. Using a Python program to model both nonlinearities and the dispersion inside the fiber, we can compute the temporal shape of the output pulse and its spectrum

3D Sonar Measurements in Wakes of Ships of Opportunity

The aim of this work is to test the potential capabilities of 3D sonar technology for studying small-scale processes in the near-surface layer of the ocean, using the centerline wake of ships of opportunity as the object of study. The first tests conducted in Tampa Bay, Florida, with the 3D sonar have demonstrated the ability of this technology to observe the shape of the centerlinewake in great detail starting from centimeter scale, using air bubbles as a proxy. An advantage of the 3Dsonar technology is that it allows quantitative estimates of the ship wake geometry, which presents new opportunities for validation of hydrodynamic models of the ship wake. Three-dimensional sonar is also a potentially useful tool for studies of air-bubble dynamics and turbulence in breaking surface waves

NECESSARY AND SUFFICIENT CONDITIONS FOR MAXIMAL REGULARITY IN THE STUDY OF ELLIPTIC DIFFERENTIAL EQUATIONS IN HÖLDER SPACES

International audienceIn this paper we give new results on complete abstract second order differential equations of elliptic type in the framework of Hölder spaces. More precisely we study u′′+2Bu′+Au=f in the case when f is Hölder continuous and under some natural assumptions on the operators A and B. We give necessary and sufficient conditions of compatibility to obtain a strict solution u and also to ensure that the strict solution has the maximal regularity property