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Computer control of stochastic distributed systems with applications to very large electrostatically figured satellite antennas

Lang, Jeffrey (Jeffrey H.)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 366 leaves; 17591355 bytes; 17591115 bytes; application/pdf; application/pdf
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by Jeffrey Hastings Lang.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980.; Includes bibliographical references.

Multivariable isoperformance methodology for precision opto-mechanical systems

De Weck, Olivier Ladislas, 1968-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 285 p.; 11956742 bytes; 11956540 bytes; application/pdf; application/pdf
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Precision opto-mechanical systems, such as space telescopes, combine structures, optics and controls in order to meet stringent pointing and phasing requirements. In this context a novel approach to the design of complex, multi-disciplinary systems is presented in the form of a multivariable isoperformance methodology. The isoperformance approach first finds a point design within a given topology, which meets the performance requirements with sufficient margins. The performance outputs are then treated as equality constraints and the non-uniqueness of the design space is exploited by trading key disturbance, plant, optics and controls parameters with respect to each other. Three algorithms (branch-and-bound, tangential front following and vector spline approximation) are developed for the bivariate and multivariable problem. The challenges of large order models are addressed by presenting a fast diagonal Lyapunov solver, apriori error bounds for model reduction as well as a governing sensitivity equation for similarity transformed state space realizations. Specific applications developed with this technique are error budgeting and multiobjective design optimization. The goal of the multiobjective design optimization is to achieve a design which is pareto optimal...

Fusion of remote vision and on-board acceleration data for the vibration estimation of large space structures

Bilton, Amy M. (Amy Marlou)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 96 leaves; 5346223 bytes; 5351035 bytes; application/pdf; application/pdf
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Future space structures such as solar power stations and telescopes are expected to be very large. These structures will require on-orbit construction. Due to the risks and costs of human extravehicular work, teams of robots will be essential for the on-orbit assembly of the large space structures. There are a number of technical challenges presented by such robotic construction. The structures will need to be made of lightweight materials and will be very flexible. Autonomous robots will require information about the vibrations of the flexible structures and their dynamic parameters in order to perform the construction efficiently. Often models of the structures are imperfect, therefore the magnitude of the vibrations of the structure must be estimated on-orbit. This thesis presents a method for estimating the shape and dynamic parameters of a vibrating large space structure. This technique is a cooperative sensing approach using remote free-flying robot observers equipped with vision sensors and structure-mounted accelerometers. This approach exploits the complementary nature of the two types of sensors.; (cont.) Vision sensors are able to measure structure deflections at a high spatial frequency but are bandwidth limited. Accelerometers are able to make measurements at high temporal frequency...

Linear theory of radiation from large space structures with induced AC current

Wang, Jiong
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: [1], 159 leaves
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by Jiong Wang.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1988.; Bibliography: leaves 118-119.

Improving particle confinement in inertial electrostatic fusion for spacecraft power and propulsion

Dietrich, Carl, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 244 p.
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Fusion energy is attractive for use in future spacecraft because of improved fuel energy density and reduced radioactivity compared with fission power. Unfortunately, the most promising means of generating fusion power on the ground (Tokamak based reactors like ITER and inertial confinement reactors like NIF) require very large and heavy structures for power supplies and magnets, in the case of magnetic confinement, or capacitors and lasers in the case of inertial confinement. The mass of these reactors and support equipment is sufficiently large that no existing or planned heavy-lift vehicle could launch such a reactor, thereby necessitating in-space construction which would substantially increase the cost of the endeavor. The scaling of Inertial Electrostatic Confinement (IEC) is such that high power densities might be achievable in small, light-weight reactors, potentially enabling more rapid, lower cost development of fusion power and propulsion systems for space applications. The primary focus of the research into improving particle and energy confinement in IEC systems is based on the idea of electrostatic ion focusing in a spherically symmetric gridded IEC system.; (cont.) Improved ion confinement in this system is achieved by the insertion of multiple concentric grids with appropriately tailored potentials to focus ion beams away from the grid wires. In order to reduce the occurrence of charge exchange and streaming electron power losses...

Design and optimization of lightweight space telescope structures

Stewart, Andrzej Matthew
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 140 p.
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As mankind attempts to look deeper into the universe, increasingly larger space telescopes will be needed to achieve the levels of resolution required to perform these missions. Due to this increase in size, increasing emphasis will be placed on designing lightweight, efficient structures in order to reduce structural mass and minimize launch costs. This thesis discusses several issues related to the design of lightweight space telescopes. Three topics are presented. The first topic deals with the design of a secondary mirror support structure. A simple tripod design is studied and optimized in detail. Several baffle--type designs are also studied and compared to the tripod. Finally, the buckling behavior of the bars in the structures is considered. The second topic deals with localized effects around the attachment points of actuators on a deformable mirror. Using a least-squares method and the coefficient of multiple determination, deformation results from a finite element model are compared to an ideal deformation shape obtained from beam bending theory. Using these results, an optimum set of dimensions is found for the actuator standoff posts that minimizes the deviation of the finite element results from the ideal shape.; (cont.) Finally...

A modular programming language for engineering design

Coffee, Thomas Merritt
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 142 p.
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We introduce a new universal model of computation called MDPL that generalizes other functional models like the lambda calculus and combinatory logic. This model leads naturally to a new type of programming language that combines the key strengths of imperative and functional languages for development and analysis of programs. These strengths have particular relevance for rapid analysis of large-scale engineering design problems. MDPL uses a novel approach to provide not only the flexibility to easily change relationships among elements in a program (as in imperative languages), but also the power to easily reuse and redeploy existing structures of such relationships in new places within a program (as in functional languages). The core formalism of MDPL is highly structured, but can be operated on by a family of formally defined algorithmic transformations that can automatically modify the structure of MDPL programs in useful ways to alter the relationships between essentially arbitrary program elements. These operations change the structure of a program to either change its functional interpretation, or to provide a different representation with the same interpretation, which may be used to make further changes. These algorithmic transformations play a critical role in rapid...

Experimental validation of the efficient robotic transportation algorithm for large-scale flexible space structures

Ono, Masahiro, S.M. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 79 p.
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A new large space structure transportation method proposed recently is modified and experimentally validated. The proposed method is to use space robots' manipulators to control the vibration, instead of their reaction jets. It requires less fuel than the reaction jet-based vibration control methods, and enables quick damping of the vibration. The key idea of this work is to use the decoupled controller, which controls the vibration mode and rigid body mode independently. The performance of the proposed method and the control algorithm is demonstrated and quantitatively evaluated by both simulation and experiments.; by Masahiro Ono.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.; Includes bibliographical references (p. 77-79).

A Model for the Thermoelastic Behavior of a Joint-Leg-Beam System for Space Applications

Cliff,E.M.; Liu,Z.; Spies,R. D.
Fonte: Revista de la Unión Matemática Argentina Publicador: Revista de la Unión Matemática Argentina
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 Português
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Rigidizable-Inflatable (RI) materials offer the possibility of deployable large space structures (C.H.M. Jenkins (ed.), Gossamer Spacecraft: Membrane and Inflatable Structures Technology for Space Applications, Progress in Aeronautics and Astronautics, 191, AIAA Pubs., 2001) and so are of interest in applications where large optical or RF apertures are needed. In particular, in recent years there has been renewed interest in inflatable-rigidizable truss-structures because of the efficiency they offer in packaging during boost-to-orbit. However, much research is still needed to better understand dynamic response characteristics, including inherent damping, of truss structures fabricated with these advanced material systems. One of the most important characteristics of such space systems is their response to changing thermal loads, as they move in and out of the Earth's shadow. We study a model for the thermoelastic behavior of a basic truss componentconsisting of two RI beams connected through a joint subject to solar heating. Axial and transverse motions as well as thermal response of the beams with thermoelastic damping are taking into account. The model results in a couple PDE-ODE system. Well-posedness and stability results are shown and analyzed.