23,696 research outputs found
Airloads research study. Volume 2: Airload coefficients derived from wind tunnel data
The development of B-1 aircraft rigid wind tunnel data for use in subsequent tasks of the Airloads Research Study is described. Data from the Rockwell International external structural loads data bank were used to generate coefficients of rigid airload shear, bending moment, and torsion at specific component reference stations or both symmetric and asymmetric loadings. Component stations include the movable wing, horizontal and vertical stabilizers, and forward and aft fuselages. The coefficient data cover a Mach number range from 0.7 to 2.2 for a wing sweep position of 67.5 degree
Airloads research study. Volume 1: Flight test loads acquisition
The acquisition of B-1 aircraft flight loads data for use in subsequent tasks of the Airloads Research Study is described. The basic intent is to utilize data acquired during B-1 aircraft tests, analyze these data beyond the scope of Air Force requirements, and prepare research reports that will add to the technology base for future large flexible aircraft. Flight test data obtained during the airloads survey program included condition-describing parameters, surface pressures, strain gage outputs, and loads derived from pressure and strain gauges. Descriptions of the instrumentation, data processing, and flight load survey program are included. Data from windup-turn and steady yaw maneuvers cover a Mach number range from 0.7 to 2.0 for a wing sweep position of 67.5 deg
Cross-Dimensional relaxation in Bose-Fermi mixtures
We consider the equilibration rate for fermions in Bose-Fermi mixtures
undergoing cross-dimensional rethermalization. Classical Monte Carlo
simulations of the relaxation process are performed over a wide range of
parameters, focusing on the effects of the mass difference between species and
the degree of initial departure from equilibrium. A simple analysis based on
Enskog's equation is developed and shown to be accurate over a variety of
different parameter regimes. This allows predictions for mixtures of commonly
used alkali atoms.Comment: 7 pages, 4 figures, uses Revtex 4. This is a companion paper to [PRA
70, 021601(R) (2004)] (cond-mat/0405419
SIGAME simulations of the [CII], [OI] and [OIII] line emission from star forming galaxies at z ~ 6
Of the almost 40 star forming galaxies at z>~5 (not counting QSOs) observed
in [CII] to date, nearly half are either very faint in [CII], or not detected
at all, and fall well below expectations based on locally derived relations
between star formation rate (SFR) and [CII] luminosity. Combining cosmological
zoom simulations of galaxies with SIGAME (SImulator of GAlaxy
Millimeter/submillimeter Emission) we have modeled the multi-phased
interstellar medium (ISM) and its emission in [CII], [OI] and [OIII], from 30
main sequence galaxies at z~6 with star formation rates ~3-23Msun/yr, stellar
masses ~(0.7-8)x10^9Msun, and metallicities ~(0.1-0.4)xZsun. The simulations
are able to reproduce the aforementioned [CII]-faintness at z>5, match two of
the three existing z>~5 detections of [OIII], and are furthermore roughly
consistent with the [OI] and [OIII] luminosity relations with SFR observed for
local starburst galaxies. We find that the [CII] emission is dominated by the
diffuse ionized gas phase and molecular clouds, which on average contribute
~66% and ~27%, respectively. The molecular gas, which constitutes only ~10% of
the total gas mass is thus a more efficient emitter of [CII] than the ionized
gas making up ~85% of the total gas mass. A principal component analysis shows
that the [CII] luminosity correlates with the star formation activity as well
as average metallicity. The low metallicities of our simulations together with
their low molecular gas mass fractions can account for their [CII]-faintness,
and we suggest these factors may also be responsible for the [CII]-faint normal
galaxies observed at these early epochs.Comment: 24 pages, 14 figures. Accepted for publication in the Astrophysical
Journa
Frequency Dependent Specific Heat from Thermal Effusion in Spherical Geometry
We present a novel method of measuring the frequency dependent specific heat
at the glass transition applied to 5-polyphenyl-4-ether. The method employs
thermal waves effusing radially out from the surface of a spherical thermistor
that acts as both a heat generator and thermometer. It is a merit of the method
compared to planar effusion methods that the influence of the mechanical
boundary conditions are analytically known. This implies that it is the
longitudinal rather than the isobaric specific heat that is measured. As
another merit the thermal conductivity and specific heat can be found
independently. The method has highest sensitivity at a frequency where the
thermal diffusion length is comparable to the radius of the heat generator.
This limits in practise the frequency range to 2-3 decades. An account of the
3omega-technique used including higher order terms in the temperature
dependency of the thermistor and in the power generated is furthermore given.Comment: 17 pages, 15 figures, Substantially revised versio
Higher-dimensional multifractal value sets for conformal infinite graph directed Markov systems
We give a description of the level sets in the higher dimensional
multifractal formalism for infinite conformal graph directed Markov systems. If
these systems possess a certain degree of regularity this description is
complete in the sense that we identify all values with non-empty level sets and
determine their Hausdorff dimension. This result is also partially new for the
finite alphabet case.Comment: 20 pages, 1 figur
vbyCaHbeta CCD Photometry of Clusters. VI. The Metal-Deficient Open Cluster NGC 2420
CCD photometry on the intermediate-band vbyCaHbeta system is presented for
the metal-deficient open cluster, NGC 2420. Restricting the data to probable
single members of the cluster using the CMD and the photometric indices alone
generates a sample of 106 stars at the cluster turnoff. The average E(b-y) =
0.03 +/- 0.003 (s.e.m.) or E(B-V) = 0.050 +/- 0.004 (s.e.m.), where the errors
refer to internal errors alone. With this reddening, [Fe/H] is derived from
both m1 and hk, using b-y and Hbeta as the temperature index. The agreement
among the four approaches is reasonable, leading to a final weighted average of
[Fe/H] = -0.37 +/- 0.05 (s.e.m.) for the cluster, on a scale where the Hyades
has [Fe/H] = +0.12. When combined with the abundances from DDO photometry and
from recalibrated low-resolution spectroscopy, the mean metallicity becomes
[Fe/H] = -0.32 +/- 0.03. It is also demonstrated that the average cluster
abundances based upon either DDO data or low-resolution spectroscopy are
consistently reliable to 0.05 dex or better, contrary to published attempts to
establish an open cluster metallicity scale using simplistic offset corrections
among different surveys.Comment: scheduled for Jan. 2006 AJ; 33 pages, latex, includes 7 figures and 2
table
Patterns in high-frequency FX data: Discovery of 12 empirical scaling laws
We have discovered 12 independent new empirical scaling laws in foreign
exchange data-series that hold for close to three orders of magnitude and
across 13 currency exchange rates. Our statistical analysis crucially depends
on an event-based approach that measures the relationship between different
types of events. The scaling laws give an accurate estimation of the length of
the price-curve coastline, which turns out to be surprisingly long. The new
laws substantially extend the catalogue of stylised facts and sharply constrain
the space of possible theoretical explanations of the market mechanisms.Comment: 26 pages, 3 figures, 23 tables,2nd version (text made more concise
and readable, algorithm pseudocode, results unchanged), 5-year datasets
(USD-JPY, EUR-USD) provided at http://www.olsen.ch/more/datasets
Plasma Magnetohydrodynamics and Energy Conversion
Contains reports on five research projects.National Science Foundation (Grant G-24073)Aeronautical Accessories Laboratory, Wright-Patterson Air Force Base, Ohio (Contract AF33(616)-7624
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