980 resultados para Geostatistical inversion


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We report performance enhancements enabled by pre-dispersed spectral inversion equivalent to that of ideal back-propagation, with further x2 increase in reach from multi-channel compensation, with spectral inversion employed upto 400km (from mid-link) with <1dB penalties. © 2012 OSA.

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Mathematics Subject Classification: 42A38, 42C40, 33D15, 33D60

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Mathematics Subject Classification 2010: 42C40, 44A12.

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Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

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Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

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Far-field stresses are those present in a volume of rock prior to excavations being created. Estimates of the orientation and magnitude of far-field stresses, often used in mine design, are generally obtained by single-point measurements of stress, or large-scale, regional trends. Point measurements can be a poor representation of far-field stresses as a result of excavation-induced stresses and geological structures. For these reasons, far-field stress estimates can be associated with high levels of uncertainty. The purpose of this thesis is to investigate the practical feasibility, applications, and limitations of calibrating far-field stress estimates through tunnel deformation measurements captured using LiDAR imaging. A method that estimates the orientation and magnitude of excavation-induced principal stress changes through back-analysis of deformation measurements from LiDAR imaged tunnels was developed and tested using synthetic data. If excavation-induced stress change orientations and magnitudes can be accurately estimated, they can be used in the calibration of far-field stress input to numerical models. LiDAR point clouds have been proven to have a number of underground applications, thus it is desired to explore their use in numerical model calibration. The back-analysis method is founded on the superposition of stresses and requires a two-dimensional numerical model of the deforming tunnel. Principal stress changes of known orientation and magnitude are applied to the model to create calibration curves. Estimation can then be performed by minimizing squared differences between the measured tunnel and sets of calibration curve deformations. In addition to the back-analysis estimation method, a procedure consisting of previously existing techniques to measure tunnel deformation using LiDAR imaging was documented. Under ideal conditions, the back-analysis method estimated principal stress change orientations within ±5° and magnitudes within ±2 MPa. Results were comparable for four different tunnel profile shapes. Preliminary testing using plastic deformation, a rough tunnel profile, and profile occlusions suggests that the method can work under more realistic conditions. The results from this thesis set the groundwork for the continued development of a new, inexpensive, and efficient far-field stress estimate calibration method.

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Français L'observation ethnographique des politisations différentielles pendant une campagne électorale en contexte autoritaire changeant est un analyseur privilégié de plusieurs processus. Sur un plan empirique, elle donne à voir les modalités diversifiées d'appropriation du moment électoral par les acteurs, les tentatives d'ajustement d'une partie de la gauche marocaine à la perte de son électorat de granit et aux transformations du marché électoral, mais également un mouvement de fond : celui de l'inversion ponctuelle du principe censitaire, en lien avec la désertion des urnes par les plus dotés culturellement et matériellement et avec la mutation du vote urbain populaire. Sur un plan théorique, l'examen des tâtonnements en oeuvre - avant leur naturalisation - permet de poursuivre le dialogue entre les travaux sur le clientélisme politique et sur la politisation, au croisement des approches socio-historiques et de sociologie politique, en contextes autoritaires et démocratiques. Il montre l'intérêt de dépasser les oppositions entre conceptions restrictives et extensives de la politisation, pour se saisir processuellement et in situ des politisations différentielles des acteurs, des registres et des pratiques. English Differential Forms of Politicization and Mutual Acculturation in an Authoritarian ContextThe ethnographic observation of differential forms of politicization during an electoral campaign in a changing authoritarian context is an ideal means of analyzing a number of processes. Empirically, it enables us to observe the actors' diverse ways of appropriating the electoral moment, a Moroccan leftist party's attempts to adjust to the loss of its electoral base and the transformations of the electoral market. It also enables us to observe a one-time reversal of the symbolic voting restrictions, in correlation with the desertion of the polls by the those best equipped to participate, both culturally and materially, and with the transformation of the urban popular vote. In theoretical terms, examination of such ongoing processes - before their stabilization - allows us to follow the interplay between the work on political clientelism and on politicization, at the intersection of sociohistorical and political sociological approaches, in authoritarian and democratic contexts. It demonstrates the value of moving beyond the opposition between restrictive and extensive conceptions of politicization, to grasp the process in situ of differential forms of the politicization of actors, registers and practices.