2,096 research outputs found
Traffic control system and method
Frequency of carrier received by aircraft is measured and compared with reference to indicate magnitude of Doppler shift. One Doppler frequency range is selected and indicated by digital signal. Difference between frequency is offset of apparent carrier frequency transmitted by aircraft
Traffic control system and method Patent
Traffic control system for supersonic transports using synchronous satellite for data relay between vehicles and ground statio
Remote sensing of the atmosphere from environmental satellites
Various applications of satellite remote sensing of the earth are reviewed, including (1) the use of meteorological satellites to obtain photographic and radiometric data for determining weather conditions; (2) determination of the earth radiation budget from measurements of reflected solar radiation and emitted long wave terrestrial radiation; (3) the use of microwave imagery for measuring ice and snow cover; (4) LANDSAT visual and near infrared observation of floods and crop growth; and (5) the use of the Nimbus 4 backscatter ultraviolet instrument to measure total ozone and vertical ozone distribution. Plans for future activities are also discussed
Electrons in the Earth's Outer Radiation Zone
Electrons in the earths outer radiation bel
Exoplanet Detection Techniques
We are still in the early days of exoplanet discovery. Astronomers are
beginning to model the atmospheres and interiors of exoplanets and have
developed a deeper understanding of processes of planet formation and
evolution. However, we have yet to map out the full complexity of multi-planet
architectures or to detect Earth analogues around nearby stars. Reaching these
ambitious goals will require further improvements in instrumentation and new
analysis tools. In this chapter, we provide an overview of five observational
techniques that are currently employed in the detection of exoplanets: optical
and IR Doppler measurements, transit photometry, direct imaging, microlensing,
and astrometry. We provide a basic description of how each of these techniques
works and discuss forefront developments that will result in new discoveries.
We also highlight the observational limitations and synergies of each method
and their connections to future space missions.Comment: 24 pages, 19 figures, PPVI proceedings. Appears as 2014, Protostars
and Planets VI, Henrik Beuther, Ralf S. Klessen, Cornelis P. Dullemond, and
Thomas Henning (eds.), University of Arizona Press, Tucson, 914 pp.,
p.715-73
Possible Stellar Metallicity Enhancements from the Accretion of Planets
A number of recently discovered extrasolar planet candidates have
surprisingly small orbits, which may indicate that considerable orbital
migration takes place in protoplanetary systems. A natural consequence of
orbital migration is for a series of planets to be accreted, destroyed, and
then thoroughly mixed into the convective envelope of the central star. We
study the ramifications of planet accretion for the final main sequence
metallicity of the star. If maximum disk lifetimes are on the order of 10 Myr,
stars with masses near 1 solar mass are predicted to have virtually no
metallicity enhancement. On the other hand, early F and late A type stars with
masses of 1.5--2.0 solar masses can experience significant metallicity
enhancements due to their considerably smaller convection zones during the
first 10 Myr of pre-main-sequence evolution. We show that the metallicities of
an aggregate of unevolved F stars are consistent with an average star accreting
about 2 Jupiter-mass planets from a protoplanetary disk having a 10 Myr
dispersal time.Comment: 14 pages, AAS LaTeX, 3 figures, accepted to ApJ Letter
Tunable far infrared laser spectrometers
The state of the art in far infrared (FIR) spectroscopy is reviewed. The development of tunable, coherent FIR radiation sources is discussed. Applications of tunable FIR laser spectrometers for measurement of rotational spectra and dipole moments of molecular ions and free radicals, vibration-rotation-tunneling (VRT) spectra of weakly bound complexes, and vibration-rotation spectra of linear carbon clusters are presented. A detailed description of the Berkeley tunable FIR laser spectrometers is presented in the following article
The Berkeley tunable far infrared laser spectrometers
A detailed description is presented for a tunable far infrared laser spectrometer based on frequency mixing of an optically pumped molecular gas laser with tunable microwave radiation in a Schottky point contact diode. The system has been operated on over 30 laser lines in the range 10–100 cm^–1 and exhibits a maximum absorption sensitivity near one part in 10^6. Each laser line can be tuned by ±110 GHz with first-order sidebands. Applications of this instrument are detailed in the preceding paper
Spin Susceptibility and Gap Structure of the Fractional-Statistics Gas
This paper establishes and tests procedures which can determine the electron
energy gap of the high-temperature superconductors using the model
with spinon and holon quasiparticles obeying fractional statistics. A simpler
problem with similar physics, the spin susceptibility spectrum of the spin 1/2
fractional-statistics gas, is studied. Interactions with the density
oscillations of the system substantially decrease the spin gap to a value of
, much less than the mean-field value of
. The lower few Landau levels remain visible, though broadened
and shifted, in the spin susceptibility. As a check of the methods, the
single-particle Green's function of the non-interacting Bose gas viewed in the
fermionic representation, as computed by the same approximation scheme, agrees
well with the exact results. The same mechanism would reduce the gap of the
model without eliminating it.Comment: 35 pages, written in REVTeX, 16 figures available upon request from
[email protected]
Recruitment Sources of Channel and Blue Catfishes Inhabiting the Middle Mississippi River
Insight into environments that contribute recruits to adult fish stocks in riverine systems is vital for effective population management and conservation. Catfish are an important recreational species in the Mississippi River and are commercially harvested. However, contributions of main channel and tributary habitats to catfish recruitment in large rivers are unknown. Stable isotope and trace elemental signatures in otoliths are useful for determining environmental history of fishes in a variety of aquatic systems, including the Mississippi River. The objectives of this study were to identify the principal natal environments of channel catfish Ictalurus punctatus and blue catfish I. furcatus in the middle Mississippi River (MMR) using otolith stable oxygen isotopic composition (δ18O) and strontium:calcium ratios (Sr:Ca). Catfishes were sampled during July-October 2013-2014 and lapilli otoliths were analyzed for δ18O and Sr:Ca. Water samples from the MMR and tributaries were collected seasonally from 2006-2014 to characterize site-specific signatures. Persistent differences in water δ18O and Sr:Ca among the MMR and tributaries (including the upper Mississippi, Illinois, and Missouri rivers as well as smaller tributaries) were evident, enabling identification of natal environment for individual fish. Blue and channel catfish stocks in the MMR primarily recruited from the large rivers (Missouri and Mississippi) in our study area, with minimal contributions from smaller tributaries. Recruitment and year class strength investigations and efforts to enhance spawning and nursery habitats should be focused in the large rivers with less emphasis in smaller tributaries
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