4,784 research outputs found
Penetration of Antarctic subglacial lakes by VHF electromagnetic pulses: Information on the depth and electrical conductivity of basal water bodies
Development and performance of power processor system for 2-gigahertz, 200-watt amplifier for communications technology satellite
The electrical and environmental requirements for a power processor system (PPS) designed to supply the appropriate voltages and currents to a 200-watt traveling wave tube (TWT) for a communication technology satellite is described. A block diagram of the PPS, the interface requirements between the PPS and spacecraft, the interface requirements between the PPS and 200-watt TWT, and the environmental requirements of the PPS are presented. Also included are discussions of protection circuits, interlocking sequences, and transient requirements. Predictions of the flight performance, based on ground test data, are provided
Legislation: The 1978 Maryland Environmental Standing Act
[A]ccess to the court of the United States is the most effective means for citizens to participate directly in environmental decisions and may be the only way to assure that democratic processes are brought to bear on environmental problems.
Legislation: The 1978 Maryland Environmental Standing Act
[A]ccess to the court of the United States is the most effective means for citizens to participate directly in environmental decisions and may be the only way to assure that democratic processes are brought to bear on environmental problems.
The Al Gamma-ray Line from Massive-Star Regions
The measurement of gamma rays from the diffuse afterglow of radioactivity
originating in massive-star nucleosynthesis is considered a laboratory for
testing models, when specific stellar groups are investigated, at known
distance and with well-constrained stellar population. Regions which have been
exploited for such studies include Cygnus, Carina, Orion, and
Scorpius-Centaurus. The Orion region hosts the Orion OB1 association and its
subgroups at about 450~pc distance. We report the detection of Al gamma
rays from this region with INTEGRAL/SPI.Comment: Contribution to Symposium "Nuclei in the Cosmos XIV", Niigata, Japan,
Jun 2016; 3 pages, 2 figures; accepted for publication in JPS (Japan Physical
Society) Conference Proceedings http://jpscp.jps.jp
Beautiful Baryons from Lattice QCD
We perform a lattice study of heavy baryons, containing one () or
two -quarks (). Using the quenched approximation we obtain for the
mass of
The mass splitting between the and the B-meson is found to increase
by about 20\% if the light quark mass is varied from the chiral limit to the
strange quark mass.Comment: 11 pages, Figures obtained upon request from [email protected]
Low temperature phase diagram and critical behaviour of the four-state chiral clock model
The low temperature behaviour of the four-state chiral clock () model
is reexamined using a systematic low temperature series expansion of the free
energy. Previously obtained results for the low temperature phases are
corrected and the low temperature phase diagram is derived. In addition, the
phase transition from the modulated region to the high temperature paraphase is
shown to belong to the universality class of the 3d-XY model.Comment: 17 pages in ioplppt style, 3 figure
Comment on "Indispensable Finite Time Correlations for Fokker-Planck Equations from Time Series Data"
Comment on "Indispensable Finite Time Correlations for Fokker-Planck
Equations from Time Series Data"Comment: 2 pages, 1 figur
Parameter uncertainty in forecast recalibration
This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Ensemble forecasts of weather and climate are subject to systematic biases in the ensemble mean and variance, leading to inaccurate estimates of the forecast mean and variance. To address these biases, ensemble forecasts are post-processed using statistical recalibration frameworks. These frameworks often specify parametric probability distributions for the verifying observations. A common choice is the Normal distribution with mean and variance specified by linear functions of the ensemble mean and variance. The parameters of the recalibration framework are estimated from historical archives of forecasts and verifying observations. Often there are relatively few forecasts and observations available for parameter estimation, and so the fitted parameters are also subject to uncertainty. This artefact is usually ignored. This study reviews analytic results that account for parameter uncertainty in the widely used Model Output Statistics recalibration framework. The predictive bootstrap is used to approximate the parameter uncertainty by resampling in more general frameworks such as Non-homogeneous Gaussian Regression. Forecasts on daily, seasonal and annual time scales are used to demonstrate that accounting for parameter uncertainty in the recalibrated predictive distributions leads to probability forecasts that are more skilful and reliable than those in which parameter uncertainty is ignored. The improvements are attributed to more reliable tail probabilities of the recalibrated forecast distributions.Stefan Siegert was supported by the European Union Programme FP7/2007–2013 under grant agreement 3038378 (SPECS). Philip Sansom was supported by a grant from the National Oceanic and Atmospheric Administration (NOAA) NA12OAR4310086
Stochastic method for in-situ damage analysis
Based on the physics of stochastic processes we present a new approach for
structural health monitoring. We show that the new method allows for an in-situ
analysis of the elastic features of a mechanical structure even for realistic
excitations with correlated noise as it appears in real-world situations. In
particular an experimental set-up of undamaged and damaged beam structures was
exposed to a noisy excitation under turbulent wind conditions. The method of
reconstructing stochastic equations from measured data has been extended to
realistic noisy excitations like those given here. In our analysis the
deterministic part is separated from the stochastic dynamics of the system and
we show that the slope of the deterministic part, which is linked to mechanical
features of the material, changes sensitively with increasing damage. The
results are more significant than corresponding changes in eigenfrequencies, as
commonly used for structural health monitoring.Comment: This paper is accepted by European Physical Journal B on November 2.
2012. 5 pages, 5 figures, 1 tabl
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