32,395 research outputs found
Fatigue testing of low-cost fiberglass composite wind turbine blade materials
The static and fatigue behavior of transverse filament tape (TFT) fiberglass/epoxy and TFT/polyester composites was established by the testing of specimens cut from panels fabricated by a filament winding process used for the construction of large experimental wind turbine blades
The Impact of Line Misidentification on Cosmological Constraints from Euclid and other Spectroscopic Galaxy Surveys
We perform forecasts for how baryon acoustic oscillation (BAO) scale and
redshift-space distortion (RSD) measurements from future spectroscopic emission
line galaxy (ELG) surveys such as Euclid are degraded in the presence of
spectral line misidentification. Using analytic calculations verified with mock
galaxy catalogs from log-normal simulations we find that constraints are
degraded in two ways, even when the interloper power spectrum is modeled
correctly in the likelihood. Firstly, there is a loss of signal-to-noise ratio
for the power spectrum of the target galaxies, which propagates to all
cosmological constraints and increases with contamination fraction, .
Secondly, degeneracies can open up between and cosmological parameters.
In our calculations this typically increases BAO scale uncertainties at the
10-20% level when marginalizing over parameters determining the broadband power
spectrum shape. External constraints on , or parameters determining the
shape of the power spectrum, for example from cosmic microwave background (CMB)
measurements, can remove this effect. There is a near-perfect degeneracy
between and the power spectrum amplitude for low values, where
is not well determined from the contaminated sample alone. This has the
potential to strongly degrade RSD constraints. The degeneracy can be broken
with an external constraint on , for example from cross-correlation with a
separate galaxy sample containing the misidentified line, or deeper
sub-surveys.Comment: 18 pages, 7 figures, updated to match version accepted by ApJ (extra
paragraph added at the end of Section 4.3, minor text edits
Angular Power Spectrum of the Microwave Background Anisotropy seen by the COBE Differential Microwave Radiometer
The angular power spectrum estimator developed by Peebles (1973) and Hauser &
Peebles (1973) has been modified and applied to the 2 year maps produced by the
COBE DMR. The power spectrum of the real sky has been compared to the power
spectra of a large number of simulated random skies produced with noise equal
to the observed noise and primordial density fluctuation power spectra of power
law form, with . Within the limited range of spatial scales
covered by the COBE DMR, corresponding to spherical harmonic indices 3 \leq
\ell \lsim 30, the best fitting value of the spectral index is with the Harrison-Zeldovich value approximately
0.5 below the best fit. For 3 \leq \ell \lsim 19, the best fit is . Comparing the COBE DMR at small to
the at from degree scale anisotropy experiments
gives a smaller range of acceptable spectral indices which includes .Comment: 22 pages of LaTex using aaspp.sty and epsf.sty with appended
Postscript figures, COBE Preprint 94-0
Quantum computers can search arbitrarily large databases by a single query
This paper shows that a quantum mechanical algorithm that can query
information relating to multiple items of the database, can search a database
in a single query (a query is defined as any question to the database to which
the database has to return a (YES/NO) answer). A classical algorithm will be
limited to the information theoretic bound of at least O(log N) queries (which
it would achieve by using a binary search).Comment: Several enhancements to the original pape
Teleportation and Secret Sharing with Pure Entangled States
We present two optimal methods of teleporting an unknown qubit using any pure
entangled state. We also discuss how such methods can also have succesful
application in quantum secret sharing with pure multipartite entangled states.Comment: Latex, 13 pages, submitted to PRA. One sub section already appeared
in the archive: quant-ph /990701
The Parity Bit in Quantum Cryptography
An -bit string is encoded as a sequence of non-orthogonal quantum states.
The parity bit of that -bit string is described by one of two density
matrices, and , both in a Hilbert space of
dimension . In order to derive the parity bit the receiver must
distinguish between the two density matrices, e.g., in terms of optimal mutual
information. In this paper we find the measurement which provides the optimal
mutual information about the parity bit and calculate that information. We
prove that this information decreases exponentially with the length of the
string in the case where the single bit states are almost fully overlapping. We
believe this result will be useful in proving the ultimate security of quantum
crytography in the presence of noise.Comment: 19 pages, RevTe
Extragalactic Point Source Search in Five-year WMAP 41, 61 and 94 GHz Maps
We present the results of an extragalactic point source search using the
five-year WMAP 41, 61 and 94 GHz (Q-, V- and W-band) temperature maps. This
work is an extension of our point source search in the WMAP maps applying a
CMB-free technique. An internal linear combination (ILC) map has been formed
from the three-band maps, with the weights chosen to remove the CMB anisotropy
signal as well as to favor a selection of flat-spectrum sources. We find 381
sources at the > 5 sigma level outside the WMAP point source detection mask in
the ILC map, among which 89 are "new" (i.e., not present in the WMAP catalog).
Source fluxes have been calculated and corrected for the Eddington bias. We
have solidly identified 367 (96.3%) of our sources. The 1 sigma positional
uncertainty is estimated to be 2'. The 14 unidentified sources could be either
extended radio structure or obscured by Galactic emission. We have also applied
the same detection process on simulated maps and found 364+/-21 detections on
average. The recovered source distribution N(>S) agrees well with the
simulation input, which proves the reliability of this method.Comment: 28 pages, 9 figures, 2 tables, accepted by Ap
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