9,707 research outputs found
Adaptive-wall wind-tunnel research at NASA-Ames Research Center
Adaptive wall wind tunnel research is summarized. Small scale two and three dimensional wind tunnel experiments and numerical experiments with a three dimensional adaptive wall simulator are included. A NACA 0012 airfoil was tested in a 25 by 13 cm slotted wall test section. Airflow through the test section walls was controlled by adjusting the pressures in segmented plenums. Interference free conditions were successfully attained in subsonic and transonic flows. For the three dimensional experiment, the 25 by 13 cm wind tunnel was modified to permit cross stream wall adjustments. The test model was a semispan wing mounted to one sidewall. Wall interference was substantially reduced at several angles of attack at Mach 0.60. A wing on wall configuration was also modeled in the numerical experiments. These flow simulations showed that free air conditions can be approximated by adjusting boundary conditions at only the floor and ceiling of the test section. No sidewall control was necessary. Typical results from these experiments are discussed
OH Maser sources in W49N: probing differential anisotropic scattering with Zeeman pairs
Our analysis of a VLBA 12-hour synthesis observations of the OH masers in
W49N has provided detailed high angular-resolution images of the maser sources,
at 1612, 1665 and 1667 MHz. The images, of several dozens of spots, reveal
anisotropic scatter broadening; with typical sizes of a few tens of
milli-arc-seconds and axial ratios between 1.5 to 3. The image position angles
oriented perpendicular to the galactic plane are interpreted in terms of
elongation of electron-density irregularities parallel to the galactic plane,
due to a similarly aligned local magnetic field. However, we find the apparent
angular sizes on the average a factor of 2.5 less than those reported by Desai
et al., indicating significantly less scattering than inferred earlier. The
average position angle of the scattered broadened images is also seen to
deviate significantly (by about 10 degrees) from that implied by the magnetic
field in the Galactic plane. More intriguingly, for a few Zeeman pairs in our
set, we find significant differences in the scatter broadened images for the
two hands of polarization, even when apparent velocity separation is less than
0.1 km/s. Here we present the details of our observations and analysis, and
discuss the interesting implications of our results for the intervening
anisotropic magneto-ionic medium, as well as a comparison with the expectations
based on earlier work.Comment: 5 pages, 3 figures, submitted to the Proceedings of the IAU Symposium
287: "Cosmic masers - from OH to H0
CO observations and investigation of triggered star formation towards N10 infrared bubble and surroundings
We studied the environment of the dust bubble N10 in molecular emission.
Infrared bubbles, first detected by the GLIMPSE survey at 8.0 m, are ideal
regions to investigate the effect of the expansion of the HII region on its
surroundings eventual triggered star formation at its borders. In this work, we
present a multi-wavelength study of N10. This bubble is especially interesting
as infrared studies of the young stellar content suggest a scenario of ongoing
star formation, possibly triggered, on the edge of the HII region. We carried
out observations of CO(1-0) and CO(1-0) emission at PMO 13.7-m
towards N10. We also analyzed the IR and sub-mm emission on this region and
compare those different tracers to obtain a detailed view of the interaction
between the expanding HII region and the molecular gas. We also estimated the
parameters of the denser cold dust condensation and of the ionized gas inside
the shell. Bright CO emission was detected and two molecular clumps were
identified, from which we have derived physical parameters. We also estimate
the parameters for the densest cold dust condensation and for the ionized gas
inside the shell. The comparison between the dynamical age of this region and
the fragmentation time scale favors the "Radiation-Driven Implosion" mechanism
of star formation. N10 reveals to be specially interesting case with gas
structures in a narrow frontier between HII region and surrounding molecular
material, and with a range of ages of YSOs situated in region indicating
triggered star formation.Comment: Version 2 - Submmited to ApJ (under review
Microscopic mass estimations
The quest to build a mass formula which have in it the most relevant
microscopic contributions is analyzed. Inspired in the successful Duflo-Zuker
mass description, the challenges to describe the shell closures in a more
transparent but equally powerful formalism are discussed.Comment: 14 pages, 6 figures, submitted to Journal of Physics G, Focus issue
on Open Problems in Nuclear Structure Theor
Intelligent distributed module for local control of lighting and electrical outlets in a home
This article proposes a control of lighting and electrical loads, suitable for smart homes, using embedded systems with low-cost wireless communication modules. The system is based on a distributed intelligent home automation architecture, to work autonomously or interconnect wirelessly to a larger system. It has a set of sensors that allow you to ration the use of electricity through automatic switching off the lights or electrical devices, allowing the lighting to be regulated. It has several modules that communicate to a central node wirelessly, and an interface based on a mobile application. UML and Petri Nets were used for the projection, modelling and validation of the system, its implementation was developed in C/C ++ language for 32-bit microcontrollers. Tests of the prototype showed stable behavior, fast communications and sufficient coverage for a single-family house, whose performance is higher to other similar works found in the scientific community
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