45,436 research outputs found
Sensitivity of galaxy cluster dark energy constraints to halo modeling uncertainties
We perform a sensitivity study of dark energy constraints from galaxy cluster
surveys to uncertainties in the halo mass function, bias and the
mass-observable relation. For a set of idealized surveys, we evaluate
cosmological constraints as priors on sixteen nuisance parameters in the halo
modeling are varied. We find that surveys with a higher mass limit are more
sensitive to mass-observable uncertainties while surveys with low mass limits
that probe more of the mass function shape and evolution are more sensitive to
mass function errors. We examine the correlations among nuisance and
cosmological parameters. Mass function parameters are strongly positively
(negatively) correlated with Omega_DE (w). For the mass-observable parameters,
Omega_DE is most sensitive to the normalization and its redshift evolution
while w is more sensitive to redshift evolution in the variance. While survey
performance is limited mainly by mass-observable uncertainties, the current
level of mass function error is responsible for up to a factor of two
degradation in ideal cosmological constraints. For surveys that probe to low
masses (10^13.5 h^-1 M_sun), even percent-level constraints on model nuisance
parameters result in a degradation of ~ sqrt{2} (2) on Omega_DE (w) relative to
perfect knowledge.Comment: 13 pages, 5 figures, accepted by PR
Inorganic glass ceramic slip rings
Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours
Sound propagation from a simple source in a wind tunnel
The nature of the acoustic field of a simple source in a wind tunnel under flow conditions was examined theoretically and experimentally. The motivation of the study was to establish aspects of the theoretical framework for interpreting acoustic data taken (in wind) tunnels using in wind microphones. Three distinct investigations were performed and are described in detail
Helical tape forming device
Using a device that is not limited to a minimum thickness or width-to-thickness ratio, a very thin metal tape or ribbon is formed into a continuous flat wound helical coil. The device imparts the desired circular shape by squeeze rolling it with an unequal force across its width
Low friction magnetic recording tape Patent
Development of low friction magnetic recording tap
Summary of the Structure Functions and Low-x working group
We report a summary of the structure function working group which covers a
wide range of the recent results from HERA, Tevatron, RHIC, and JLab
experiments, and many theoretical issues from low x to high x.Comment: 20 pages, presented at 13th International Workshop on Deep Inelastic
Scattering (DIS 05), Madison, Wisconsin, 27 Apr - 1 May 200
Simulating study of the interaction between the propulsion and flight control systems of a subsonic lift fan VTOL
The possibility of interactions between the propulsion and flight control systems of a three-fan subsonic VTOL aircraft was studied using nonreal time simulation. Time histories of critical internal engine parameters were obtained and possible deleterious effects of engine dynamics on flight control were identified and analyzed. No deleterious effects, with the exception of the effects of the fan actuator deadband, were found. A method of alleviating these effects through feedback of the actuator output to the flight controller was developed
New Deal policies and the persistence of the Great Depression: a general equilibrium analysis
There are two striking aspects of the recovery from the Great Depression in the United States: the recovery was very weak and real wages in several sectors rose significantly above trend. These data contrast sharply with neoclassical theory, which predicts a strong recovery with low real wages. We evaluate the contribution of New Deal cartelization policies designed to limit competition and increase labor bargaining power to the persistence of the Depression. We develop a model of the bargaining process between labor and firms that occurred with these policies, and embed that model within a multi-sector dynamic general equilibrium model. We find that New Deal cartelization policies are an important factor in accounting for the post-1933 Depression. We also find that the key depressing element of New Deal policies was not collusion per se, but rather the link between paying high wages and collusion.Depressions
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