38,240 research outputs found
Intensity-Correlation Spectroscopy
A survey is given of techniques for spectroscopic analysis using intensity fluctuations. Particular attention is given to counting times, the role of macroscopic sources and detectors, and the electronic constraints placed on the observations
Registration of Heat Capacity Mapping Mission day and night images
Neither iterative registration, using drainage intersection maps for control, nor cross correlation techniques were satisfactory in registering day and night HCMM imagery. A procedure was developed which registers the image pairs by selecting control points and mapping the night thermal image to the daytime thermal and reflectance images using an affine transformation on a 1300 by 1100 pixel image. The resulting image registration is accurate to better than two pixels (RMS) and does not exhibit the significant misregistration that was noted in the temperature-difference and thermal-inertia products supplied by NASA. The affine transformation was determined using simple matrix arithmetic, a step that can be performed rapidly on a minicomputer
Advanced Computer Dormant Reliability Study Final Report
Reliability of integrated circuits and discrete components of electronics for computer and dormant module for Minuteman
High Redshift Standard Candles: Predicted Cosmological Constraints
We investigate whether future measurements of high redshift standard candles
(HzSCs) will be a powerful probe of dark energy, when compared to other types
of planned dark energy measurements. Active galactic nuclei and gamma ray
bursts have both been proposed as potential HzSC candidates. Due to their high
luminosity, they can be used to probe unexplored regions in the expansion
history of the universe. Information from these regions can help constrain the
properties of dark energy, and in particular, whether it varies over time.
We consider both linear and piecewise parameterizations of the dark energy
equation of state, , and assess the optimal redshift distribution a
high-redshift standard-candle survey could take to constrain these models.
The more general the form of the dark energy equation of state being
tested, the more useful high-redshift standard candles become. For a linear
parameterization of , HzSCs give only small improvements over planned
supernova and baryon acoustic oscillation measurements; a wide redshift range
with many low redshift points is optimal to constrain this linear model.
However to constrain a general, and thus potentially more informative, form of
, having many HzSCs can significantly improve limits on the nature of
dark energy.Comment: Accepted MNRAS, 27 Pages, 15 figures, matches published versio
Information extraction and transmission techniques for spaceborne synthetic aperture radar images
Information extraction and transmission techniques for synthetic aperture radar (SAR) imagery were investigated. Four interrelated problems were addressed. An optimal tonal SAR image classification algorithm was developed and evaluated. A data compression technique was developed for SAR imagery which is simple and provides a 5:1 compression with acceptable image quality. An optimal textural edge detector was developed. Several SAR image enhancement algorithms have been proposed. The effectiveness of each algorithm was compared quantitatively
Delayed soft X-ray emission lines in the afterglow of GRB 030227
Strong, delayed X-ray line emission is detected in the afterglow of GRB
030227, appearing near the end of the XMM-Newton observation, nearly twenty
hours after the burst. The observed flux in the lines, not simply the
equivalent width, sharply increases from an undetectable level (<1.7e-14
erg/cm^2/s, 3 sigma) to 4.1e-14 erg/cm^2/s in the final 9.7 ks. The line
emission alone has nearly twice as many detected photons as any previous
detection of X-ray lines. The lines correspond well to hydrogen and/or
helium-like emission from Mg, Si, S, Ar and Ca at a redshift z=1.39. There is
no evidence for Fe, Co or Ni--the ultimate iron abundance must be less than a
tenth that of the lighter metals. If the supernova and GRB events are nearly
simultaneous there must be continuing, sporadic power output after the GRB of a
luminosity >~5e46 erg/s, exceeding all but the most powerful quasars.Comment: Submitted to ApJL. 14 pages, 3 figures with AASLaTe
Lifetime and decay of unstable particles in S-matrix theory
An investigation is made of the possible time dependence of decay laws for unstable particles. The probability P(t) that an unstable particle has not decayed at time t is expressed in terms of S-matrix quantities. It is concluded that, contrary to popular belief, the exponential decay law P=e-Γt is only one of a discrete set of possible decay laws
FearNot! An Anti-Bullying Intervention: Evaluation of an Interactive Virtual Learning Environment
Original paper can be found at: http://www.aisb.org.uk/publications/proceedings.shtm
Fluctuations with time of scattered-particle intensities
The fluctuations in counting rate of a particle detector are studied. These may be used to study the coherence properties of the beam. For the case of electromagnetic radiation they may be used to study spectral line shapes. The fluctuations in intensity of scattered particles provide a means of studying fluctuation phenomena in the target
FLUKA Simulations of Energy Density Deposition from a ILC Bunch in different Spoiler Designs
FLUKA is used to simulate the energy deposition due to a direct bunch impact of the ILC beam in various candidate spoiler designs. The conclusions extracted will contribute to the overall optimisation process and identify areas where additional experimental data would be beneficial
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