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Se estudia una porción de la Faja Plegada y Corrida de Malargüe en el sur de los Andes Centrales (Cordillera Principal), Mendoza, Argentina, entre los 34 40 - 35 de latitud sur y 69 - 70 de longitud Oeste. Este área se encuentra regionalmente vinculada en su génesis y evolución al margen continental activo de América del Sur. Se caracteriza por un basamento volcaniclástico-plutónico de edad Permotriásica al que sobreyace una secuencia sedimentaria Triásica a Terciaria diferenciada en los Grupos Cuyo, Lotena, Mendoza, Rayoso, Neuquén, Malargüe y unidades cenozoicas que en conjunto suman un espesor mayor a los 6200 metros. La construcción de este sector del orógeno, asociada a la tectónica andina, involucra al basamento definiéndose a la faja plegada y corrida de Malargüe como epidérmica gruesa. La deformación del basamento y su vinculación con la cubierta sedimentaria permite explicar algunos rasgos notables para las estructuras ándicas de este sector de la Cordillera Principal, como la variación en el rumbo, cambios en la longitud de onda de los pliegues, presencia de múltiples despegues dentro de la cubierta sedimentaria o grandes variaciones de acortamiento entre regiones próximas. El objetivo de esta tesis es desarrollar un modelo cinemático para este sector de la Cordillera Principal argentina, sustentado en un detallado trabajo de superficie y apoyado por los datos disponibles de perforaciones y sísmica. Se interpretan y reconstruyen tres secciones estructurales de 60 km de longitud orientadas en dirección Oeste-Este, subperpendiculares a la dirección relevada para las estructuras tectónicas asociadas a la orogenia andina. Los afloramientos del Grupo Cuyo ocupan la porción occidental de estas secciones, mientras que el Mesozoico medio y alto queda restringido al centro localizándose las unidades terciarias en el borde oriental. Se interpretan dos altos de basamento cuyo rasgo superficial corresponde a importantes sinclinorios, denominados alto del arroyo El Freno y alto del arroyo Blanco, siendo el corrimiento asociado a este último el responsable de la exhumación del Grupo Cuyo desplazándose como falla fuera de secuencia en el último estadio de la evolución del área. La deformación del basamento por fallamiento retrovergente asociado a corrimientos regionales provergentes se revela como una posibilidad altamente confiable para la resolución de problemas tectónicos tanto en este como en otros sectores de la Cordillera Principal. Existe un notable desarrollo espacial de zonaciones estructurales asociadas a la geometría que presenta el basamento para esta porción de la Faja Plegada y Corrida de Malargüe en respuesta al crecimiento y avance del zócalo deformado como resultado de la compresión andina. Se observa una secuencialidad de eventos que permite definir un modelo progresivo en el tiempo, en donde la zonación estructural producida en respuesta a la deformación del zócalo es posteriormente afectada por el desarrollo de una nueva estructura de basamento. Los acortamientos medidos sustentan la imposibilidad de la inversión tectónica como mecanismo de construcción y avance del frente montañoso para esta porción de la Faja Plegada y Corrida de Malargüe, debiendo considerarse aplicar esta posibilidad con mucha cautela en otros sectores de la Cordillera Principal. / This thesis involves the study of the Malargüe Fold and Thrust belt, part of the Central Andes at the southern Cordillera Principal, Mendoza province, Argentina (34 40 35 S and 69 - 70W). The tectonic setting and evolution of the area is controlled by the continental active margin of the South America plate. The Malargüe Fold and Thrust belt is characterized by a volcaniclastic-plutonic Permian-Triassic basement which overlies a sedimentary sequence represented by Cuyo, Lotena, Mendoza, Rayoso, Neuquén and Malargüe Groups and cenozoic units, with more than 6200 meters of thickness. Construction of the mountain front is related to Andean tectonics and involves basement thrust sheets, defining a thick-skinned fold and thrust belt in this particular site of the Central Andes. Relationship between basement and fault and fold sedimentary cover allow us to explain some particular features for Andean structures at the Atuel river valley, such as strike variations, fold wave-length changes, multiple detachments horizons located into the sedimentary cover or different shortening between near localities. The aim of this thesis is to develop a kinematic model for this zone of Cordillera Principal province, supported in a detail field work and well and seismic available data. Three West-East structural sections with 60 km of length are interpreted and reconstructed, subperpendicular to tectonic orientation mapped for Andean structures. Cuyo Group outcrops are located at the western side of the sections, while middle and upper Mesozoic remains restricted to the centre and tertiary deposits are located at the eastern side. According to this, two structural basement highs where interpreted named as arroyo El Freno high and arroyo Blanco high. Regional major thrust involved to the elevation of the arroyo Blanco high is interpreted as responsible of Cuyo Group exhumation, related to an out-of sequence displacement that affects folded Mesozoic sequence in the latest stadium of tectonic evolution of the area. Basement deformation associated to regional master foreland thrusts and the developed of backthrusting appears to be a high confident possibility of resolution of tectonics problems in this area as well in another places of Cordillera Principal Province. There is notable structural zonation related to the basement geometry at this site of Malargüe Fold and Thrust belt in response to the growing and forward movement of deformed crystalline basement as a result of Andean compression. A temporal sequence of events can be observed allowing us to define a progressive model, where the previous structural zonation is affected for a new local basement structure. Shortening measures support impossibility of tectonic inversion of rifting Triassic normal fault system as a viable mechanism of construction y evolvement of mountain front for this part of Malargüe Fold and Thrust belt; a carefully consideration to this option in the study of others sides of Cordillera Principal is suggested.

Vacuum arc thrusters offer a relatively simple and cheap form of satellite propulsion, especially suitable for nanosatellites such as CubeSats or even smaller. This thesis focuses on vacuum arc thruster design considering the thruster’s manufacturing, assembly and integration into the spacecraft, and proposes a new anode geometry easing thruster production. Vacuum arc thruster research is traditionally experimental in nature due to a lack of accurate models. This work follows this approach, and studies experimentally the effect of several geometric design parameters on thruster performance. The outcome confrms findings from several papers, and suggests specifc improvements towards existing models for predicting the effect of the thruster’s geometry on its thrust. The chosen experimental approach raised the need for a micro-thrust measurement stand. Two distinct measurement stands have been designed, realized and used to test various thruster prototypes. One test stand is more accurate. However, the other setup allows for considerably faster testing.

A nonlinear programming technique is applied to the optimization of the thrust and lift control histories for missiles. The first problem considered is that of determining the thrust history which maximizes the range of a continuously-variable (non-pulsed) thrust rocket in horizontal lifting flight. The optimal control solution for this problem is developed. The problem is then approximated by a parameter optimization problem which is solved using a second-order, quasi-Newton method with constraint projection. The two solutions are found to compare well. This result allows confidence in the use of the nonlinear-programming technique to solve optimization problems in flight mechanics for which no analytical optimal-control solutions exist. Such a problem is to determine the thrust and lift histories which maximize the final velocity of a multiple-pulse missile. This problem is solved for both horizontal- and elevation-plane trajectories with and without final time constraints. The method is found to perform well in the solution of these optimization problems and to yield substantial improvements in performance over the nominal trajectories. / M.S.

The problem of maximizing the altitude of a rocket in vertical flight has been extensively analyzed by many writers since the early days of rocketry. In the beginning, solutions were obtained using the classical theory of the Calculus of Variations, and later using Optimal Control theory. For strict assumptions on the drag law and the thrust, solutions were found, even in a closed, analytic form. Nevertheless, for more realistic conditions, the problem becomes a very complex one, and the solution is far from complete. In addition to this, complexity increases if an isoperimetric constraint is added to the problem. Such a case is, for example, the problem of extremizing the rise in altitude for a given time. In the present work an attempt is made to treat the problem under the most realistic assumptions used so far, for both the system of equations and the drag model. The analysis of the problem reveals that a more complex thrust history exists than the classical sequence of full-singular-coast subarcs, for both the time-constrained case, and for the case of a drag model with a sharp rise in the transonic region. In the first case, a second full-thrust subarc is generated at the end of the singular subarc, owing to the boundedness of the thrust, while, in the second case, a full-thrust subarc appears in transition from the subsonic to the supersonic branch of the singular path. Both are new results, at least for the bounded-thrust case, and the drag law assumed, insofar as the author knows. Discussion is also provided for the limitations of such a switching structure, and it is shown that the composition of an optimal trajectory is heavily dependent on the assumed drag law. / Master of Science

Folding prior to thrust-sheet emplacement is proposed to explain presence of overturned synclines in the footwalls of many thrust-faults in the Appalachian foreland fold- and thrust-belt of southwest Virginia. Investigation of relations in the footwalls of the Saltville and St. Clair thrust-sheets near the Southern-Central Appalachian juncture indicates presence of at least two distinct types of footwall structures: 1)isolated forelimbs of thrust-truncated asymmetric ramp-generated anticlines, and 2)areally extensive overturned subthrust synclines. Mesoscopic fabric data and strain states indicate rotation of bedding by folding prior to thrust-sheet emplacement rather than drag folding during thrusting. Low angles between bedding and cleavage planes and low strain values on the back limbs of folds at thrust terminations (Sinking Creek anticline) and in hangingwall strata seems to indicate folding was largely accomplished by flexural flow in units of relatively low mechanical strength. / M.S.

Reprocessing of Appalachian Ultradeep Core Hole (ADCOH) southern Appalachian seismic reflection data was focused on improving the reflection imaging and hence interpretability of seismic signatures previously interpreted as duplexes created by thrust stacking of thin beds of Paleozoic shelf strata. The reprocessed data are used to determine a more unique depth domain geometry for one of the proposed duplexes. Reprocessed data are partially improved through an increase in both stacking velocity coverage and datum statics velocity coverage as well as an appropriate use of residual statics. Interpretability increases from the improvement in resolution and the consideration of geologic strike direction relative to profile direction. Initial shotpoint ray trace modeling shows the chaotic nature of raypaths and some of the problems associated with the imaging of reflections when complex geology is involved. Data reprocessing and two-dimensional ray trace modeling yield results which suggest that the studied seismic signature is part of a broad hinterland-dipping duplex. At the trailing edge of the duplex itself beds appear to be successively fault truncated, perhaps explaining the increased amplitude and reflectivity in this zone. The truncations result in a wedge-shaped geometry that resembles the trailing edge of an antiformal stack duplex. The improved data also show 1) a shallow band of reflections that correlate with the Shope Fork and Chunky Gal Mountain faults within the Blue Ridge allochthon, 2) thrust ramping initiated by basement faulting that extends only a short distance into the overlying sedimentary strata, 3) a more highly faulted Grenville basement surface and, 4) almost intact Paleozoic shelf strata (?) being carried along the thrust surface serving and bounding the hinterland-dipping duplex. / M.S.