12,303 research outputs found
Thematic mapper design parameter investigation
This study simulated the multispectral data sets to be expected from three different Thematic Mapper configurations, and the ground processing of these data sets by three different resampling techniques. The simulated data sets were then evaluated by processing them for multispectral classification, and the Thematic Mapper configuration, and resampling technique which provided the best classification accuracy were identified
Evaluation of a semi-active gravity gradient system. Volume I - Technical summary
Semi-active gravity gradient system for attitude control of earth oriented spacecraf
Evaluation of a semi-active gravity gradient system. Volume II - Appendices
Evaluation of semi-active gravity gradient system - appendixe
Arctic marine climate of the early nineteenth century
The climate of the early nineteenth century is likely to have been significantly cooler than that of today, as it was a period of low solar activity (the Dalton minimum) and followed a series of large volcanic eruptions. Proxy reconstructions of the temperature of the period do not agree well on the size of the temperature change, so other observational records from the period are particularly valuable. Weather observations have been extracted from the reports of the noted whaling captain William Scoresby Jr., and from the records of a series of Royal Navy expeditions to the Arctic, preserved in the UK National Archives. They demonstrate that marine climate in 1810 - 1825 was marked by consistently cold summers, with abundant sea-ice. But although the period was significantly colder than the modern average, there was considerable variability: in the Greenland Sea the summers following the Tambora eruption (1816 and 1817) were noticeably warmer, and had less sea-ice coverage, than the years immediately preceding them; and the sea-ice coverage in Lancaster Sound in 1819 and 1820 was low even by modern standards. © 2010 Author(s)
The Nature and Purpose of Work and Productivity
The authors discuss the importance of the work-rest cycle for daily living
Searching for the expelled hydrogen envelope in Type I supernovae via late-time H-alpha emission
We report the first results from our long-term observational survey aimed at
discovering late-time interaction between the ejecta of hydrogen-poor Type I
supernovae and the hydrogen-rich envelope expelled from the progenitor star
several decades/centuries before explosion. The expelled envelope, moving with
a velocity of ~10 -- 100 km s, is expected to be caught up by the
fast-moving SN ejecta several years/decades after explosion depending on the
history of the mass-loss process acting in the progenitor star prior to
explosion. The collision between the SN ejecta and the circumstellar envelope
results in net emission in the Balmer-lines, especially in H-alpha. We look for
signs of late-time H-alpha emission in older Type Ia/Ibc/IIb SNe having
hydrogen-poor ejecta, via narrow-band imaging. Continuum-subtracted H-alpha
emission has been detected for 13 point sources: 9 SN Ibc, 1 SN IIb and 3 SN Ia
events. Thirty-eight SN sites were observed on at least two epochs, from which
three objects (SN 1985F, SN 2005kl, SN 2012fh) showed significant temporal
variation in the strength of their H-alpha emission in our DIAFI data. This
suggests that the variable emission is probably not due to nearby H II regions
unassociated with the SN, and hence is an important additional hint that
ejecta-CSM interaction may take place in these systems. Moreover, we
successfully detected the late-time H-alpha emission from the Type Ib SN 2014C,
which was recently discovered as a strongly interacting SN in various (radio,
infrared, optical and X-ray) bands.Comment: 8 pages, 7 figures, accepted in Ap
Relative entropy via non-sequential recursive pair substitutions
The entropy of an ergodic source is the limit of properly rescaled 1-block
entropies of sources obtained applying successive non-sequential recursive
pairs substitutions (see P. Grassberger 2002 ArXiv:physics/0207023 and D.
Benedetto, E. Caglioti and D. Gabrielli 2006 Jour. Stat. Mech. Theo. Exp. 09
doi:10.1088/1742.-5468/2006/09/P09011). In this paper we prove that the cross
entropy and the Kullback-Leibler divergence can be obtained in a similar way.Comment: 13 pages , 2 figure
On factorizing -matrices in and spin chains
We consider quantum spin chains arising from -fold tensor products of the
fundamental evaluation representations of and .
Using the partial -matrix formalism from the seminal work of Maillet and
Sanchez de Santos, we derive a completely factorized expression for the
-matrix of such models and prove its equivalence to the expression obtained
by Albert, Boos, Flume and Ruhlig. A new relation between the -matrices and
the Bethe eigenvectors of these spin chains is given.Comment: 30 page
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