13,275 research outputs found
A generalized approach to dynamic-stability flight analysis
Energy integral equation for dynamic stability flight analysi
Sparsely Sampling the Sky: A Bayesian Experimental Design Approach
The next generation of galaxy surveys will observe millions of galaxies over
large volumes of the universe. These surveys are expensive both in time and
cost, raising questions regarding the optimal investment of this time and
money. In this work we investigate criteria for selecting amongst observing
strategies for constraining the galaxy power spectrum and a set of cosmological
parameters. Depending on the parameters of interest, it may be more efficient
to observe a larger, but sparsely sampled, area of sky instead of a smaller
contiguous area. In this work, by making use of the principles of Bayesian
Experimental Design, we will investigate the advantages and disadvantages of
the sparse sampling of the sky and discuss the circumstances in which a sparse
survey is indeed the most efficient strategy. For the Dark Energy Survey (DES),
we find that by sparsely observing the same area in a smaller amount of time,
we only increase the errors on the parameters by a maximum of 0.45%.
Conversely, investing the same amount of time as the original DES to observe a
sparser but larger area of sky we can in fact constrain the parameters with
errors reduced by 28%
Entry Dynamics of a Spinning Vehicle
Solution for angular motion analysis on spinning atmospheric entry vehicl
A Submillimeter Selected Quasar in the Field of Abell 478
We report the discovery of a z=2.83 quasar in the field of the cooling flow
galaxy cluster Abell 478. This quasar was first detected in a submm survey of
star forming galaxies at high redshifts, as the brightest source. We discuss
the optical spectrum and far-IR spectral energy distribution (SED) of this
object.Comment: 4 pages, 3 figures, in "Deep Millimeter Surveys: Implications for
Galaxy Formation and Evolution", ed. J. Lowenthal and D. Hughes, World
Scientific Publisher
Secondary and compound concentrators for parabolic dish solar thermal power systems
A secondary optical element may be added to a parabolic dish solar concentrator to increase the geometric concentration ratio attainable at a given intercept factor. This secondary may be a Fresnel lens or a mirror, such as a compound elliptic concentrator or a hyperbolic trumpet. At a fixed intercept factor, higher overall geometric concentration may be obtainable with a long focal length primary and a suitable secondary matched to it. Use of a secondary to increase the geometric concentration ratio is more likely to e worthwhile if the receiver temperature is high and if errors in the primary are large. Folding the optical path with a secondary may reduce cost by locating the receiver and power conversion equipment closer to the ground and by eliminating the heavy structure needed to support this equipment at the primary focus. Promising folded-path configurations include the Ritchey-Chretien and perhaps some three element geometries. Folding the optical path may be most useful in systems that provide process heat
Chiral-Odd and Spin-Dependent Quark Fragmentation Functions and their Applications
We define a number of quark fragmentation functions for spin-0, -1/2 and -1
hadrons, and classify them according to their twist, spin and chirality. As an
example of their applications, we use them to analyze semi-inclusive
deep-inelastic scattering on a transversely polarized nucleon.Comment: 19 pages in Plain TeX, MIT CTP #221
Novel Quark Fragmentation Functions and the Nucleon's Transversity Distribution
We define twist-two and twist-three quark fragmentation functions in Quantum
Chromodynamics (QCD) and study their physical implications. Using this
formalism we show how the nucleon's transversity distribution can be measured
in single pion inclusive electroproduction.Comment: 10 pages, uses PHYZZX macro package, 2 PostScript figures (added
using FIGURES). MIT-CTP-215
The Quantum Effective Action, Wave Functions and Yang-Mills (2+1)
We explore the relationship between the quantum effective action and the
ground state (and excited state) wave functions of a field theory. Applied to
the Yang-Mills theory in 2+1 dimensions, we find the leading terms of the
effective action from the ground state wave function previously obtained in the
Hamiltonian formalism by solving the Schrodinger equation.Comment: 16 pages, expanded discussion section, added references, version
accepted for Phys. Rev.
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