26,671 research outputs found
Spectral characterization of the LANDSAT Thematic Mapper sensors
The spectral coverage characteristics of the two thematic mapper instruments were determined by analyses of spectral measurements of the optics, filters, and detectors. The following results are presented: (1) band 2 and 3 flatness was slightly below specification, and band 7 flatness was below specification; (2) band 5 upper-band edge was higher than specifications; (3) band 2 band edges were shifted upward about 9 nm relative to nominal; and (4) band 4, 5, and 7 lower band edges were 16 to 18 nm higher then nominal
Introduction to Thematic Mapper investigations. Section 1: Radiometry. Section 2: Geometry
An overview of papers which deal with radiometric characterization of the TM sensor is presented. Spectral characteristics are summarized. The geometric accuracy of TM are also examined. Aspects of prelaunch and post launch sensor performance, ground processing techniques, and error correction are also investigated
Analytical simulation of the Langley Research Center integrated life-support system, volume 1
Analytical simulation of integrated life support system and oxygen recovery syste
Spectral characterization of the LANDSAT-D multispectral scanner subsystems
Relative spectral response data for the multispectral scanner subsystems (MSS) to be flown on LANDSAT-D and LANDSAT-D backup, the protoflight and flight models, respectively, are presented and compared to similar data for the Landsat 1,2, and 3 subsystems. Channel-bychannel (six channels per band) outputs for soil and soybean targets were simulated and compared within each band and between scanners. The two LANDSAT-D scanners proved to be nearly identical in mean spectral response, but they exhibited some differences from the previous MSS's. Principal differences between the spectral responses of the D-scanners and previous scanners were: (1) a mean upper-band edge in the green band of 606 nm compared to previous means of 593 to 598 nm; (2) an average upper-band edge of 697 nm in the red band compared to previous averages of 701 to 710 nm; and (3) an average bandpass for the first near-IR band of 702-814 nm compared to a range of 693-793 to 697-802 nm for previous scanners. These differences caused the simulated D-scanner outputs to be 3 to 10 percent lower in the red band and 3 to 11 percent higher in the first near-IR band than previous scanners for the soybeans target. Otherwise, outputs from soil and soybean targets were only slightly affected. The D-scanners were generally more uniform from channel to channel within bands than previous scanners
Balloon borne humidity and aerosol sensors
Infrared detectors for balloon sensing of aerosols and atmospheric moistur
Online peer support for students
While many UK higher education institutions have websites offering information and advice on common student problems, interactive online support is less common. This article describes a project developing internet-based mutual support for students experiencing psychological problems at University College London
Digging into research
Non-Peer ReviewedCanadianAgronomist.ca translates research into agronomic knowledge that agronomists and farmers can use to grow better crops. CanadianAgronomist.ca helps to fill the technology transfer gap between researchers, agronomists and farmers by summarizing research from peer-reviewed academic journals and final research reports into easily accessible Research Insights that agronomists and farmers can use to improve crop production practices. Stay up up-to-date on recent research findings. Agronomists, farmers, researchers, students and other agricultural advisors can sign up for a free subscription to receive email notifications of new Research Insights postings roughly every two weeks. Research Insights will be archived on the website, and a search function can be used to access specific topics. Canadian Agronomist.ca is possible through the generous sponsorships of grower supported commodity groups and maintains independence from advertisers. Platinum and Founding Sponsor Western Grains Research Foundation Gold Alberta Canola Silver Alberta Wheat Bronze Alberta Barley Sask Canola Prairie Oat Growers Associatio
Transition from inspiral to plunge in precessing binaries of spinning black holes
We investigate the non-adiabatic dynamics of spinning black hole binaries by
using an analytical Hamiltonian completed with a radiation-reaction force,
containing spin couplings, which matches the known rates of energy and angular
momentum losses on quasi-circular orbits. We consider both a straightforward
post-Newtonian-expanded Hamiltonian (including spin-dependent terms), and a
version of the resummed post-Newtonian Hamiltonian defined by the Effective
One-Body approach. We focus on the influence of spin terms onto the dynamics
and waveforms. We evaluate the energy and angular momentum released during the
final stage of inspiral and plunge. For an equal-mass binary the energy
released between 40Hz and the frequency beyond which our analytical treatment
becomes unreliable is found to be, when using the more reliable Effective
One-Body dynamics: 0.6% M for anti-aligned maximally spinning black holes, 5% M
for aligned maximally spinning black hole, and 1.8% M for non-spinning
configurations. In confirmation of previous results, we find that, for all
binaries considered, the dimensionless rotation parameter J/E^2 is always
smaller than unity at the end of the inspiral, so that a Kerr black hole can
form right after the inspiral phase. By matching a quasi-normal mode ringdown
to the last reliable stages of the plunge, we construct complete waveforms
approximately describing the gravitational wave signal emitted by the entire
process of coalescence of precessing binaries of spinning black holes.Comment: 31 pages, 7 tables, and 13 figure
Cavity cooling of an optically trapped nanoparticle
We study the cooling of a dielectric nanoscale particle trapped in an optical
cavity. We derive the frictional force for motion in the cavity field, and show
that the cooling rate is proportional to the square of oscillation amplitude
and frequency. Both the radial and axial centre-of-mass motion of the trapped
particle, which are coupled by the cavity field, are cooled. This motion is
analogous to two coupled but damped pendulums. Our simulations show that the
nanosphere can be cooled to 1/e of its initial momentum over time scales of
hundredths of milliseconds.Comment: 11 page
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