180,491 research outputs found
Maximum likelihood method for fitting the Fundamental Plane of the 6dF Galaxy Survey
We have used over 10,000 early-type galaxies from the 6dF Galaxy Survey
(6dFGS) to construct the Fundamental Plane across the optical and near-infrared
passbands. We demonstrate that a maximum likelihood fit to a multivariate
Gaussian model for the distribution of galaxies in size, surface brightness and
velocity dispersion can properly account for selection effects, censoring and
observational errors, leading to precise and unbiased parameters for the
Fundamental Plane and its intrinsic scatter. This method allows an accurate and
robust determination of the dependencies of the Fundamental Plane on variations
in the stellar populations and environment of early-type galaxies.Comment: 3 pages, 1 figure, to appear in the proceedings of the IAU Symposium
262 "Stellar Populations: Planning for the Next Decade", Charlot and Bruzual
ed
Vibrational transfer functions for base excited systems
Computer program GD203 develops transfer functions to compute governing vibration environment for complex structures subjected to a base motion
Magnets with stabilized conductors
Method fabricates stabilized composite conductor, for use in construction of magnets, using equal amounts of superconducting and metal materials, thus reducing weight, cost and size
Shock absorber Patent
Design and development of double acting shock absorber for spacecraft docking operation
Rotational joint assembly for the prosthetic leg
A rotational joint assembly for a prosthetic leg has been devised, which enables an artificial foot to rotate slightly when a person is walking, running or turning. The prosthetic leg includes upper and lower tubular members with the rotational joint assembly interposed between them. The assembly includes a restrainer mechanism which consists of a pivotably mounted paddle element. This device applies limiting force to control the rotation of the foot and also restores torque to return the foot back to its initial position
Shock absorber operates over wide range
Piston-type hydraulic shock absorber, with a metered damping system, operates over a wide range of kinetic energy loading rates. It is used for absorbing shock and vibration on mounted machinery and heavy earth-moving equipment
A numerical determination of the bow shock wave in transonic axisymmetric flow about blunt bodies
A numerical method was developed for calculating axisymmetric transonic (M greater than 1) flow about a blunt body; the bow shock wave location was investigated. A Rankine-Hugoniot jump was applied at the shock while relaxation on the isentropic equation of motion was used between shock and body. The shock wave is adjusted by a Newton type iteration scheme. Results are given for a sphere in the Mach number range 1.62 down to 1.02
Incident shock-wave characteristics in air, argon, carbon dioxide, and helium in a shock tube with unheated helium driver
Incident shock-wave velocities were measured in the Langley 6-inch expansion tube, operated as a shock tube, with air, argon, carbon dioxide, and helium as test gases. Unheated helium was used as the driver gas and most data were obtained at pressures of approximately 34 and 54 MN/sq m. A range of pressure ratio across the diaphragm was obtained by varying the quiescent test-gas pressure, for a given driver pressure, from 0.0276 to 34.5 kN/sq m. Single- and double-diaphragm modes of operation were employed and diaphragms of various materials tested. Shock velocity was determined from microwave interferometer measurements, response of pressure transducers positioned along interferometer measurements, response of pressure transducers positioned along the driven section (time-of-arrival gages), and to a lesser extent, measured tube-wall pressure. Velocities obtained from these methods are compared and limitations of the methods discussed. The present results are compared with theory and the effects of diaphragm mode (single or double diaphragm), diaphragm material, heating of the driver gas upon pressurization of the driver section, diaphragm opening time, interface mixing, and two-dimensional (nonplanar) flow are discussed
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