113,554 research outputs found
Welding torch and wire feed manipulator
Welding torch and wire feed manipulator increase capability for performing automatic welding operations. The manipulator rotates on its horizontal axis to avoid obstacles as they approach the torch. The initial individual attitudes of the torch and wire guide are set with respect to the general configuration of the part
Magnetic ionization fronts II: Jump conditions for oblique magnetization
We present the jump conditions for ionization fronts with oblique magnetic
fields. The standard nomenclature of R- and D-type fronts can still be applied,
but in the case of oblique magnetization there are fronts of each type about
each of the fast- and slow-mode speeds. As an ionization front slows, it will
drive first a fast- and then a slow-mode shock into the surrounding medium.
Even for rather weak upstream magnetic fields, the effect of magnetization on
ionization front evolution can be important. [Includes numerical MHD models and
an application to observations of S106.]Comment: 9 pages, 10 figures, Latex, to be published in MNRA
Research in and application of state variable feedback design of guidance control systems for aerospace vehicles Progress report
Weighted least squares parameter estimation, Kalman filter, and random search problems for aerospace guidance control system desig
Chemical reaction of atomic oxygen with evaporated films of copper, part 4
Evaporated copper films were exposed to an atomic oxygen flux of 1.4 x 10(exp 17) atoms/sq cm per sec at temperatures in the range 285 to 375 F (140 to 191 C) for time intervals between 2 and 50 minutes. Rutherford backscattering spectroscopy (RBS) was used to determine the thickness of the oxide layers formed and the ratio of the number of copper to oxygen atoms in the layers. Oxide film thicknesses ranged from 50 to 3000 A (0.005 to 0.3 microns, or equivalently, 5 x 10(exp -9) to 3 x 10(exp -7); it was determined that the primary oxide phase was Cu2O. The growth law was found to be parabolic (L(t) varies as t(exp 1/2)), in which the oxide thickness L(t) increases as the square root of the exposure time t. The analysis of the data is consistent with either of the two parabolic growth laws. (The thin-film parabolic growth law is based on the assumption that the process is diffusion controlled, with the space charge within the growing oxide layer being negligible. The thick-film parabolic growth law is also based on a diffusion controlled process, but space-charge neutrality prevails locally within very thick oxides.) In the absence of a voltage measurement across the growing oxide, a distinction between the two mechanisms cannot be made, nor can growth by the diffusion of neutral atomic oxygen be entirely ruled out. The activation energy for the reaction is on the order of 1.1 eV (1.76 x 10(exp -19) joule, or equivalently, 25.3 kcal/mole)
Control system design using optimization techniques Final report
Optimization techniques for control of fuel valve systems for air breathing jet engines and 40-60 inlet control problem
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