17,911 research outputs found
Design Features And Stress Analysis Of A 0.686-Scale Standard Dynamics Model
A 0 .686-Scale Standard Dynamics Model Incorporating Some Tpecial Features Was Designed And Built At NAL .A Brief . Description Of The Various Design And Construction Features, Load Estimations And A Detailed Stress Analysis Of The Model Are Presented In The Report To Provide An Idea Of The Current Practice Adopted At NAL For The Design And Construction Of Wind Tunnel Models For Dynamic Stability Testing . The Model Was Successfully Employed For Check-Out And Validation Of A Forced-Oscillation Rig At Mach Numbers Up to 1.3 And Angles Of Attack Up to 20 Deg In The NAL 1.2m Blowdown Tunne
Prospects of dynamical determination of General Relativity parameter beta and solar quadrupole moment J2 with asteroid radar astronomy
We evaluated the prospects of quantifying the parameterized post-Newtonian
parameter beta and solar quadrupole moment J2 with observations of near-Earth
asteroids with large orbital precession rates (9 to 27 arcsec century).
We considered existing optical and radar astrometry, as well as radar
astrometry that can realistically be obtained with the Arecibo planetary radar
in the next five years. Our sensitivity calculations relied on a traditional
covariance analysis and Monte Carlo simulations. We found that independent
estimates of beta and J2 can be obtained with precisions of
and , respectively. Because we assumed rather conservative
observational uncertainties, as is the usual practice when reporting radar
astrometry, it is likely that the actual precision will be closer to
and , respectively. A purely dynamical determination
of solar oblateness with asteroid radar astronomy may therefore rival the
helioseismology determination.Comment: The astrophysical journal (ApJ), in pres
Flow reversals in turbulent convection via vortex reconnections
We employ detailed numerical simulations to probe the mechanism of flow
reversals in two-dimensional turbulent convection. We show that the reversals
occur via vortex reconnection of two attracting corner rolls having same sign
of vorticity, thus leading to major restructuring of the flow. Large
fluctuations in heat transport are observed during the reversal due to this
flow reconfiguration. The flow configurations during the reversals have been
analyzed quantitatively using large-scale modes. Using these tools, we also
show why flow reversals occur for a restricted range of Rayleigh and Prandt
numbers
INPOP new release: INPOP13b
Based on the use of MESSENGER radiotracking data in the construction of new
Mercury ephemerides (Verma et al. 2014) a new planetary ephemerides INPOP13b
was built including Mercury improvements but also improvements on the Mars
orbit and on the tie of INPOP planetary ephemerides to ICRF in general.Comment: INPOP sources available http://www.imcce.fr/inpo
Incompressible Turbulence as Nonlocal Field Theory
It is well known that incompressible turbulence is nonlocal in real space
because sound speed is infinite in incompressible fluids. The equation in
Fourier space indicates that it is nonlocal in Fourier space as well. Contrast
this with Burgers equation which is local in real space. Note that the sound
speed in Burgers equation is zero. In our presentation we will contrast these
two equations using nonlocal field theory. Energy spectrum and renormalized
parameters will be discussed.Comment: 7 pages; Talk presented in Conference on "Perspectives in Nonlinear
Dynamics (PNLD 2004)" held in Chennai, 200
Computation of Kolmogorov's Constant in Magnetohydrodynamic Turbulence
In this paper we calculate Kolmogorov's constant for magnetohydrodynamic
turbulence to one loop order in perturbation theory using the direct
interaction approximation technique of Kraichnan. We have computed the
constants for various , i.e., fluid to magnetic energy ratios
when the normalized cross helicity is zero. We find that increases from
1.47 to 4.12 as we go from fully fluid case to a situation when , then it decreases to 3.55 in a fully magnetic limit .
When , we find that .Comment: Latex, 10 pages, no figures, To appear in Euro. Phys. Lett., 199
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