173 research outputs found
MODE: Structural Test Article (STA)
Viewgraphs on the Middeck 0-gravity Dynamics Experiment (MODE): Structural Test Article (STA) are presented. Topics covered include: MODE: structural test article motivation; hardware; sensors and actuators; experimental support module; data; preliminary results; supporting analysis program; and modeling approach
Multiple degree of freedom force-state component identification
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1994.Includes bibliographical references (p. 159-162).by Brett P. Masters.M.S
Evolutionary design of controlled structures
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1997.Includes bibliographical references (p. 209-213).by Brett P. Masters.Ph.D
Quaternary faulting in the New Madrid seismic zone in southernmost Illinois
U.S. Geological Survey, Department of the Interior, National Earthquake Hazards Reduction Program Award No. 1434-95-G-2525Ope
Quaternary faulting in the New Madrid seismic zone in southernmost Illinois
U.S. Geological Survey, Department of the Interior, under USGS award number 1434-95-G-2525Ope
SDSS-IV MaNGA: Spatially resolved star formation in barred galaxies
A novel wave-energy device is presented. Both a preliminary proof-of-principle of a working, scaled laboratory version of the energy device is shown as well as the derivation and analysis of a comprehensive mathematical and numerical model of the new device. The wave-energy device includes a convergence in which the waves are amplified, a constrained wave buoy with a (curved) mast and direct energy conversion of the buoy motion into electrical power via an electro-magnetic generator. The device is designed for use in breakwaters and it is possible to be taken out of action during severe weather. The new design is a deconstruction of elements of existing wave-energy devices, such as the TapChan, IP wave-buoy and the Berkeley Wedge, put together in a different manner to enhance energy conversion and, hence, efficiency. The idea of wave-focusing in a contraction emerged from our work on creating and simulating rogue waves in crossing seas, including a “bore-soliton-splash”. Such crossing seas have been recreated and modelled in the laboratory and in simulations by using a geometric channel convergence. The mathematical and numerical modelling is also novel. One monolithic variational principle governs the dynamics including the combined (potential-flow) hydrodynamics, the buoy motion and the power generation, to which the dissipative elements such as the electrical resistance of the circuits, coils and loads have been added a posteriori. The numerical model is a direct and consistent discretisation of this comprehensive variational principle. Preliminary numerical calculations are shown for the case of linearised dynamics; optimisation of efficiency is a target of future work
SDSS-IV MaNGA: spatially resolved dust attenuation in spiral galaxies
Dust attenuation in star-forming spiral galaxies affects stars and gas in
different ways due to local variations in dust geometry. We present spatially
resolved measurements of dust attenuation for a sample of 232 such star-forming
spiral galaxies, derived from spectra acquired by the SDSS-IV MaNGA survey. The
dust attenuation affecting the stellar populations of these galaxies (obtained
using full spectrum stellar population fitting methods) is compared with the
dust attenuation in the gas (derived from the Balmer decrement). Both of these
attenuation measures increase for local regions of galaxies with higher star
formation rates; the dust attenuation affecting the stellar populations
increases more so than the dust attenuation in the gas, causing the ratio of
the dust attenuation affecting the stellar populations to the dust attenuation
in the gas to decrease for local regions of galaxies with higher star formation
rate densities. No systematic difference is discernible in any of these dust
attenuation quantities between the spiral arm and inter-arm regions of the
galaxies. While both the dust attenuation in the gas and the dust attenuation
affecting the stellar populations decrease with galactocentric radius, the
ratio of the two quantities does not vary with radius. This ratio does,
however, decrease systematically as the stellar mass of the galaxy increases.
Analysis of the radial profiles of the two dust attenuation measures suggests
that there is a disproportionately high concentration of birth clouds
(incorporating gas, young stars and clumpy dust) nearer to the centres of
star-forming spiral galaxies.Comment: 17 pages, 8 figures, accepted for publication in Monthly Notices of
the Royal Astronomical Societ
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