Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vii, 102 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 91-94).

This work is aimed towards the development of an artificially intelligent search algorithm used in conjunction with an Auto Associative Neural Network (AANN) to help locate and reconstruct faulty sensor inputs in control systems. The AANN can be trained to detect when sensors go faulty but the problem of locating the faulty sensor still remains. The search algorithm aids the AANN to help locate the faulty sensors and reconstruct their actual values. The algorithm uses domain specific heuristics based on the inherent behavior of the AANN to achieve its task. Common sensor errors such as drift, shift and random errors and the algorithms response to them have been studied. The issue of noise has also been investigated. These areas cover the first part of this work. The second part focuses on the development of a web interface that implements and displays the working of the algorithm. The interface allows any client on the World Wide Web to connect to the engineering software called MATLAB. The client can then simulate a drift, shift or random error using the graphical user interface and observe the response of the algorithm.

La tolérance et la gestion des fautes dans les grilles de données/calcul est d’une importance capitale. En effet, comme dans tout autre système distribué, les composants d’une grille sont susceptibles de tomber en panne à tout moment. Mais le risque de panne croît avec la taille du système, et est donc plus exacerbé dans un système de grille. En plus, tout en essayant de mettre à profit les ressources offertes par la grille, les applications tournant sur celle-ci sont de plus en plus complexes (ex. impliquent des interactions complexes, prennent des jours d’exécution), ce qui les rend plus vulnérables aux fautes. Le plus difficile dans la gestion des fautes dans une grille, c’est qu’il est difficile de savoir si une faute qui survient sur une entité de la grille est induite malicieusement ou accidentellement. Dans notre travail de thèse, nous utilisons le terme faute, au sens large, pour faire référence à tout étant inattendu qui survient sur tout composant de la grille. Certains de ces états provoquent des comportements aussi inattendus et perceptibles au niveau de la grille tandis que d’autres passent inaperçues. De plus, certaines de ces fautes sont le résultat d’une action malveillante alors que d’autres surviennent accidentellement ou instantanément. Dans ce travail de thèse, nous avons traité le cas de ces fautes induites malicieusement, et qui généralement passent inaperçues. Nous avons considéré en particulier le problème de la confidentialité et de l’intégrité des données stockées à long-terme sur la grille. L’étude de la confidentialité des données a été faite en deux temps dont la première partie concerne la confidentialité des données actives. Dans cette partie, nous avons considéré une application liée à la recherche des similitudes d’une séquence d’ADN dans une base de données contenant des séquences d’ADN et stockée sur la grille. Pour cela, nous avons proposé une méthode qui permet d’effectuer la comparaison sur un composant distant, mais tout en gardant confidentielle la séquence qui fait l’objet de la comparaison. Concernant les données passives, nous avons proposé une méthode de partage des données confidentielles et chiffrés sur la grille. En rapport avec l’intégrité des données, nous avons considéré le cas des données anonymes dans le cadre de l’intégrité des données passives. Pour les données actives, nous avons considéré le problème de la corruption des jobs exécutés sur la grille. Pour chacune des cas, nous avons proposé des mécanismes permettant de vérifier l’authenticité des données utilisées ou produites par ces applications.

Among the renewable energies, wind energy presents the highest growth in installed capacity and penetration in modern power systems. This is why reliability of wind turbines becomes an important topic in research and industry. To this end, condition monitoring (or health monitoring) systems are needed for wind turbines. The core of any condition monitoring system (CMS) are fault diagnosis algorithms whose task is to provide early warnings upon the occurrence of incipient (small magnitude) faults. Thanks to the use of CMS we can avoid premature breakdowns and reduce significatively maintenance costs. The present thesis deals with fault diagnosis in sensors of a doubly-fed induction generator (DFIG) for wind turbine (WT) applications. In particular we are interested in performing fault detection and isolation (FDI) of incipient faults affecting the measurements of the three-phase signals (currents and voltages) in a controlled DFIG. Although different authors have dealt with FDI for sensors in induction machines and in DFIGs, most of them rely on the machine model with constant parameters. However, the parameter uncertainties due to changes in the operating conditions will produce degradation in the performance of such FDI systems. In this work we propose a systematic methodology for the design of sensor FDI systems with the following characteristics: i) capable of detecting and isolating incipient additive (bias, drifts) and multiplicative (changes in the sensor gain) faults, ii) robust against changes in the references/disturbances affecting the controlled DFIG as well as modelling/parametric uncertainties, iii) residual generation system based on a multi-observer strategy to enhance the isolation process, iv) decision system based on statistical-change detection algorithms to treat the entire residual and perform fault detection and isolation at once. Three novel sensor FDI approaches are proposed. The first is a signal-based approach, that uses the model of the balanced three-phase signals (currents or voltages) for residual generation purposes. The second is a model-based approach that accounts for variation in the parameters. Finally, a third approach that combines the benefits of both the signal- and the model-based approaches is proposed. The designed sensor FDI systems have been validated using measured voltages, as well as simulated data from a controlled DFIG and a speed-controlled induction motor. In addition, in this work we propose a discrete-time multiple input multiple output (MIMO) regulator for each power converter, namely for the rotor side converter (RSC) and for the grid side converter (GSC). In particular, for RSC control, we propose a modified feedback linearization technique to obtain a linear time invariant (LTI) model dynamics for the compensated DFIG. The novelty of this approach is that the compensation does not depend on highly uncertain parameters such as the rotor resistance. For GSC control, a LTI model dynamics is derived using the ideas behind feedback linearization. The obtained LTI model dynamics are used to design Linear Quadratic Gaussian (LQG) regulators. A single design is needed for all the possible operating conditions.

Two fundamental structural elements, basement architecture and basal decollement, play a significant role in the evolution of a tectonically active region. Using different approaches (field data, literature review and analogue models) this thesis demonstrates that these two elements affected the deformation style in the Zagros fold-thrust belt during Mesozoic extensional and Cenozoic contractional episodes. Reassessment of available data suggests a new configuration for the basement to Zagros basin that consists of basement faults with three different trends. Complicated interrelationships of these basement faults divide the Zagros basin into two major basement blocks, active and passive. This model associated with geological evidence suggests that deformation in the basement due to the convergence between Arabia and Iran is not restricted to the Zagros Mountains but already involves a considerable part of the Arabian platform. However, deformation in the cover units is not only governed by the deformation in the basement, which are decoupled from each other by the Hormuz salt in many parts in the Zagros fold-thrust belt. Geological evidence shows that there is a clear relationship between activity of the Hormuz structures and the basement faults in the Zagros basin. Extended analogue models indirectly show how Hormuz types of basal decollement associated with the opening of Neo-Tethys can control the distribution, number, width and geometry of faults, penetrative strain, and diapirism. Analogue models shortened from one-end show that the spatial distribution of the Hormuz salt in the Zagros belt map viscous and frictional decollements to the thin-skinned deformation. Shortening of the cover results in formation of partitioning of strain into transpressional zones, different topographic wedges and differential sedimentation of growth sediments along the Zagros belt. Model results supported by geological and geophysical data sets suggest that some of the faults previously attributed to basement could have developed above the initial lateral boundaries between viscous and frictional basal decollements.

This thesis studies and compares existing Numerical Result checking algorithms for FFT computations under faults. In order to simulate faulty conditions, a fault injection tool is implemented. The fault injection tool is designed so as to be as non-intrusive to the application as possible. Faults are injected into memory in the form of bit flips in the data elements of the application. The performance of the three result checking algorithms under these conditions is studied and compared. Faults are injected at all the stages of the FFT computation by flipping each of the 64-bits in the double-precision representation. Experiments also include introducing random bit flips in the data array, emulating a more real-life like scenario. Finally the performance of these algorithms under a set of worst-case is also studied

In the northern Gulf of Mexico, seafloor hydrocarbon fluid and gas seepage is an ubiquitous process on the continental margin. Although seafloor seepage and seep-related features (mud volcanoes, carbonate formation) have been studied for many years, little is known about their mechanisms of formation and the relationship of sub-surface structure to current seep activity. In this study, we examined three seafloor seeps in the Garden Banks and Mississippi Canyon areas using exploration and reprocessed 3D multi-channel seismic (MCS) data augmented with side-scan sonar (Garden Banks site) to characterize hydrocarbon seep activity and develop an understanding of the processes that led to their formation. Side-scan sonar data provided high resolution coverage of the seafloor while the exploration seismic data were used to image near and deep sub-surface features. Additionally, the 3D amplitude extraction maps were useful in delineating amplitude anomalies often associated with seep related activity. The reprocessed 3D seismic data were used to map in greater detail near seafloor features and amplitude anomalies. Using remote sensing geophysical data, we were effectively able to map sub-surface features such as salt topography, seep-related faults and geophysical indicators of hydrocarbons and correlate them with seafloor amplitude anomalies and fault traces in order to characterize seep activity level. The southern mud volcano in the Garden Banks site is characterized as an established high flux seep vent owing to signs of active seepage and sediment flows as well as the build-up of hard grounds. The northern mud volcano in the area, with greater hard ground build-up and fewer signs of active seepage represents an established low flux seep vent. In the Mississippi Canyon area, the data suggest that the seep mound can be characterized as a mature high flux vent due to the extensive build-up of hard ground, evidence of gas hydrates and signs of active seepage and sediment flows. The mechanisms of formation are similar between the two study sites. Upwelling salt appears to have fractured the sub-surface leading to the formation of fault induced depressions. Mapping of geophysical indicators of hydrocarbons implies that hydrocarbon migration is occurring along bedding planes to the fault systems underlying the depressions. Here they appear to migrate vertically to the seafloor creating the topographic features and seafloor amplitude anomalies that characterize the seeps

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 20, 2010). Includes bibliographical references. Also issued in print.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vi, 63 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 29-37).

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 128-140).