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Full-Text Articles in Mechanical Engineering
Integrated Control Of Thermally Distorted Large Space Antennas, Robert H. Tolson
Integrated Control Of Thermally Distorted Large Space Antennas, Robert H. Tolson
Mechanical & Aerospace Engineering Theses & Dissertations
Studies on controlling the thermal distortion of large space antennae have generally investigated a single orbital position and have optimized actuator locations based on minimizing the RMS surface deviation from the original parabolic shape. One study showed the benefits of directly using far zone electric field characteristics as the performance measure; but, this approach resulted in a nonlinear programming problem. The objective of the current study is to develop an approach to designing a control system that (1) recognizes the time dependence of the distortion and (2) controls variables that are directly related to far field performance in a quadratic …
Nonproportionally Loaded Steel Beam-Columns And Flexibly-Connected Nonsway Frames, Siva Prasad Darbhamulla
Nonproportionally Loaded Steel Beam-Columns And Flexibly-Connected Nonsway Frames, Siva Prasad Darbhamulla
Civil & Environmental Engineering Theses & Dissertations
A theoretical study of the inelastic stability of nonproportionally loaded steel beam-columns and flexibly-connected frames is conducted. Specifically, solution techniques are formulated to predict the nonlinear behavior of cross sections, spatial beam-columns, and nonsway plane frames under the combined influence of imperfections, flexible connections, and nonproportional loads. A set of new inelastic slope-deflection equations for imperfect members are derived and their use illustrated through in-depth studies of flexibly-connected portal and two-bay two-story frames. These equations are derived from a system of nonlinear ordinary differential equations. The member studies are carried out using a second-order finite-difference solution to a set of …