Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 22 for “"gravity gradient"”.
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Rotational locks for gravity gradient satellites
… rotational motion for satellites moving in a gravity gradient field is examined using both analytical and numerical techniques. It is shown that rotational locks at spin rates of n/2 (where n is an integer) satellite rotations per orbit revolution exist for specific combinations of satellite …
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Gravity gradient study of the central Honey Lake Basin, Lassen County, California
Includes bibliographical references.
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Water - Gravity - Gradient: A gathering in the floodplain of the Hout Bay valley
This dissertation departs with an enduring interest in matter. The research, in turn, becomes focused primarily on physicality and its implications for people. An empathetic attitude towards considering material developed as a founding precept for the design endeavour. The project can be described …
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Performance analysis of a GPS interferometric attitude determination system for a gravity gradient stabilized spacecraft
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1995.
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A Nonlinear Magnetic Controller for Three-Axis Stability of Nanosatellites
… through simulations, and the results for gravity-gradient stable and non gravity-gradient stable spacecraft are compared. An optimization technique is implemented in an attempt to obtain the best performance from the controller. For every spacecraft configuration, a set of gains can be …
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Exercise under artificial gravity - experimental and computational approaches
… state within acceptable limits. Artificial gravity has long been suggested as a comprehensive countermeasure that is capable of challenging all the physiological systems at the same time, therefore maintaining overall health during extended weightlessness. Ground studies have shown that …
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Dual Quaternions for Gravity Recovery Missions
… methods which are currently utilized for gravity recovery missions. The proposed modeling and control approach was verified against and compared to the tangent bundle to Special Euclidean Group 3 through MATLAB simulations. The dual quaternion-based approach shows superior performance over …
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Mesozoic Rift Evolution and Crustal Structure of the Gulf of Mexico Basin from Integration of Multiple Geological and Geophysical Datasets
… This dissertation integrates satellite free-air gravity data, full-tensor gravity gradient data, 104,000 line-kilometers of 2D reflection data, and publicly available refraction data and deep wells over 4.2 million km2 to improve our understanding of the GOM rift history. Chapter 1 summarizes the …
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Towards detecting gravitational waves from the Crab Pulsar
… radiation. Noteworthy examples include Newtonian gravity gradient, seismic, acoustic, thermal and photon shot noise. These are the obstacles that must be confronted by the planned upgrade to the LIGO detectors, Advanced LIGO. To achieve improved sensitivity, significant improvements of LIGO's …
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Design, analysis, and testing of a precision guidance, navigation, and control system for a dual-spinning Cubesat
… This orientation leaves the spacecraft at a gravity-gradient-unstable equilibrium. Further, imperfect cancellation of the payload's angular momentum induces nutation behavior. An extended Kalman filter is implemented on a 16-bit P1C24 microcontroller to combine gyroscope, limb sensor, and …
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Novel approaches to Newtonian noise suppression in interferometric gravitational wave detection
… LIGO noise in the 1-10 Hz range is Newtonian (or gravity gradient) noise which arises from local fluctuations in the Earth's gravitational field. Density fluctuations from seismic activity as well as acoustic and turbulent phenomenon in the Earth's atmosphere both contribute to slight variations …
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Squat exercise biomechanics during short-radius centrifugation
Artificial gravity (AG) created by short-radius centrifugation is a promising countermeasure to the physiological de-conditioning that results from long-duration spaceflight. However, as on Earth, gravity alone does not ensure fitness. We will need to supplement passive exposure to AG with physical …
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Understanding dark matter halos with tidal caustics
… of the tidal caustics. We find that the local gravity and gravity gradient of the larger galaxy, and the energy spread and initial phase space density of the smaller galaxy, can be jointly constrained by fitting this profile. The constraints are degenerate but model-independent. We find that …
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Determining the ability of terrestrial time-lapse microgravity surveying on a glacier to find summer mass balance using gravitational modeling
… gravimetric methods using data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite mission. However, the former can be logistically costly and have large extrapolation errors: measurements taken at monthly temporal scales are expensive and have a spatial resolution of …
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Kalman Filter Implementation to Determine Orbit and Attitude of a Satellite in a Molniya Orbit
… in the rotational equations of motion model: gravity gradient torque, solar pressure torque, magnetic torque, and aerodynamic torque. Four cases were tested corresponding to four different on board attitude determining sensors: magnetometer, Earth sensor, sun sensor, and star tracker. A …
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Dynamics and Control of a Tensegrity System in Low-Earth Orbit
… forces in the tendons or external forces such as gravity. However, a balance of sorts must be maintained - if a tendon were to go slack, the entire structure could become unstable and collapse on itself. This thesis looks at placing a tensegrity structure in orbit around the Earth. As a …
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Development of Hardware and Efficient, Robust Control Algorithms for a Nanosatellite Reaction Control System
… in the space environment, including magnetic and gravity gradient torques, aerodynamic forces, solar radiation pressure, and propellant sloshing. Iterative hardware development is performed of a thruster module suitable for use on nanosatellites, including detailed evaluations of different …
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Stratigraphy and Structure of the Miocene "Esmeralda" Formation in Stewart Valley, Mineral County, Nevada
… eastward dip of the sediments and the steep gravity gradient near the Cedar Mountains, suggests tilted block faulting. The Gabbs Valley Range-Stewart Valley block was tilted east and was dropped relative to the Cedar Mountain block.</p>
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Applications of Roll-Along Electrical Resistivity Surveying in Conjunction with Other Geophysical Methods for Engineering and Environmental Site Characterization
… used with seismic refraction, magnetometer and gravity surveying in geophysical characterization of sites with a specific environmental or engineering problem. Three examples are presented where resistivity surveying provided vital constraints on acquisition and interpretation of other data in …
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Attitude Determination & Control System Design and Implementation for a 6U CubeSat Proximity Operations Mission
… by aerodynamic drag, solar radiation pressure, gravity gradient torques, and residual magnetic moments. A mechanical propellant slosh model and a reaction torque analysis of the deployable solar panel hinges approximate the internal dynamics of the satellite. A trade study is presented to …
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