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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 15 of 15 for “"Moving Mass"”.
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A Moving Mass on A String
Made available in DSpace on 2014-12-04T23:10:58Z (GMT). No. of bitstreams: 1 5900575.pdf: 1730510 bytes, checksum: 3213ab4f4cf9a3258b60b006d7851045 (MD5) Previous issue date: 1958
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A Moving Mass on an Infinite Beam
Made available in DSpace on 2014-12-04T23:11:01Z (GMT). No. of bitstreams: 1 6100213.pdf: 2116602 bytes, checksum: d7380578d21afd5d4042d7183a42e686 (MD5) Previous issue date: 1960
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Mars Precision Entry Vehicle Guidance Using Internal Moving Mass Actuators
… missions. This dissertation develops internal moving mass actuator (IMMA) control systems for improving Mars precision entry guidance of rigid capsules and demonstrating precision guidance capability for HIADs. IMMAs provide vehicle control moments without direct interaction with the external …
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Assessment of moving-mass actuators for hypersonic vehicles with deployable decelerators
This study assesses internal moving-mass actuator configuration options for trajectory control in the hypersonic regime of planetary entry. Trajectory control is achieved by shifting the location of the center of gravity relative to the center of pressure to modify aerodynamic trim conditions. The …
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Modular Modification of a Buoyant AUV for Low-Speed Operation
… speeds, one may easily incorporate a modular moving mass actuator. In some cases, it may also be advantageous to include a fixed wing. The equations of motion and equilibrium conditions to regulate depth are derived, and the effectiveness and low-speed efficiency of a fixed wing is evaluated. …
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Hydrodynamic Modeling for Autonomous Underwater Vehicles Using Computational and Semi-Empirical Methods
… their buoyancy and their attitude with moving mass actuators and inflatable bladders, are proving their worth as efficient long-distance, long-duration ocean sampling platforms. Gliders have the capability to travel thousands of kilometers without a need to stop or recharge. There is a …
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Practical Challenges in the Method of Controlled Lagrangians
… is applied to vehicle systems with internal moving point mass actuators. Applications of moving mass actuators include certain spacecraft, atmospheric re-entry vehicles, and underwater vehicles. Control design using moving mass actuators is challenging; the system is often underactuated and …
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Optimal Paths in Gliding Flight
… of these efficient (but traditionally slow moving) vehicles. This dissertation aims to improve the performance of shallow water underwater gliders through path planning. The path planning problem is formulated for a dynamic particle (or "kinematic car") model. The objective is to identify …
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A Multiple Degree of Freedom Actuator using a single vibrating transducer
… transducer, is derived. An efficient, low-moving-mass moving magnet transducer is developed and shown to greatly improve theoretical system efficiency. Finally, a hypocycloid speed reducer mechanism is developed and fabricated to achieve a very high reduction ratio in a compact package with …
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Hydrology of a large unstable hillslope at Ebnit, Vorarlberg : identifying dominating processes and structures
… of control mechanisms of hydrological induced mass movements. To this end, detailed hydrological process studies and physically-based hydrological modelling were applied. The study site is a hillslope in the Dornbirn Ache valley near Bregenz, Austria. This so called Heumös slope features a …
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Adaptive Control and Estimation of the Center of Mass of a 5-degree-of-freedom Spacecraft Testbed
… of rotation (<em>CoR</em>) and the center of mass (<em>CoM</em>) of the testbed, which makes the system behave like a three-dimensional pendulum.</p> <p>Testbeds with rotational degrees of freedom must be designed to minimize this offset. However, manufacturing and assembly precision is …
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Design and control methods for high-accuracy variable reluctance actuators
… of providing high force densities (force per moving mass) and lower power values relative to the present state-of-the-art Lorentz actuators that are used to drive the reticle stage. However, reluctance actuators are highly nonlinear with both current and air gap. They also display other …
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Modeling and monitoring of the dynamic response of railroad bridges using wireless smart sensors
… bridges and railroad bridges. Usually, the mass of the vehicles crossing highway bridges is assumed to be relatively small compared to the mass of the bridge itself; as a result, the mass of the vehicles are often neglecting in the problem. In contrast, the mass of a train crossing a …
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Reliability based live loads for structural assessment of bridges on heavy-haul railway lines
… derived using 2 dimensional beam model with moving masses is presented. The approximate formulae predicts the reduced frequency within 12% of the estimate from field vibration measurements of an 11 span continuous bridge with train to bridge linear mass ratio of 88%. The approximate formula …
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Design, control and error analysis of a fast tool positioning system for ultra-precision machining of freeform surfaces
… The influences of mechanical parameters such as mass, damping, and stiffness were investigated within the closed-loop framework. Under a given disturbance condition, the optimal bearing stiffness and optimal damping coefficients were found. Experimental positioning tests showed that a larger …