17,823 research outputs found
Computer program analyzes and designs supersonic wing-body combinations
Computer program formulates geometric description of the wing body configuration, optimizes wing camber shape, determines wing shape for a given pressure distribution, and calculates pressures, forces, and moments on a given configuration. The program consists of geometry definition, transformation, and paneling, and aerodynamics, and flow visualization
Ferroelectricity in the xAg2Nb4O11–(1−x)Na2Nb4O11 solid solution
Compositions in the (AgxNa1-x)2Nb4O11 solid solution have been prepared by a conventional
solid state method. Composites containing Ag2Nb4O11 have been shown to be ferroelectric
and the Curie temperature shown to decrease from 149 °C at x = 1 to 62 °C at x = 0.7. Roomtemperature
compositions with x ≤ 0.7 are monoclinic, while those with x ≥ 0.8 are
rhombohedral with structures consistent with the relevant end-members. At x = 0.75, the
structure was mainly rhombohedral but with coexistence of the monoclinic structure,
indicating the proximity of a phase boundary
Improved method for aerodynamic analysis of wing-body-tail configurations in subsonic and supersonic flow
Method permits analysis of noncircular bodies and calculation of wing-body interference effects in presence of body closure, two features not previously available. In addition, use of vortex distribution, having linear variation in streamwise direction, results in improved chordwise pressure distributions on wing and tail surfaces
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Calibration and comparison of chlorine decay models for a test water distribution system
This paper investigates the kinetics of monochloramine as disinfectant in a 1.3 km water pipe. A novel procedure for the correction of chlorine meter errors is introduced and applied. Parameter estimation using nonlinear optimisation procedures is used to identify decay coefficients for monochloramine models with a single coefficient or two coefficients as used in EPANET. Important difficulties in fitting these parameters which come about because of the model structure are highlighted. Finally, results of
decay coefficients are presented and investigated for flow, inlet chlorine concentration and temperature dependence
Infrared Observations of novae in the SOFIA era
Classical novae inject chemically enriched gas and dust into the local
inter-stellar medium (ISM). Abundances in the ejecta can be deduced from
infrared (IR) forbidden line emission. IR spectroscopy can determine the
mineralogy of grains that grow in nova ejecta. We anticipate the impact that
NASA's new Stratospheric Observatory for Infrared Astronomy (SOFIA) will have
on future IR studies of novae.Comment: To appear in the proceedings of "Physics of Evolved Stars 2015 - A
conference dedicated to the memory of Olivier Chesneau
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