38,974 research outputs found
Electron Population Aging Models for Wide-Angle Tails
Color-color diagrams have been useful in studying the spectral shapes in
radio galaxies. At the workshop we presented color-color diagrams for two
wide-angle tails, 1231+674 and 1433+553, and found that the standard aging
models do not adequately represent the observed data. Although the JP and KP
models can explain some of the observed points in the color-color diagram, they
do not account for those found near the power-law line. This difficulty may be
attributable to several causes. Spectral tomography has been previously used to
discern two separate electron populations in these sources. The combination
spectra from two such overlying components can easily resemble a range of
power-laws. In addition, any non-uniformity in the magnetic field strength can
also create a power-law-like spectrum. We will also discuss the effects that
angular resolution has on the shape of the spectrum.Comment: 4 pages, 1 figure, proceedings from 1999 'Life Cycles of Radio
Galaxies' workshop at STScI in Baltimore, M
What do we know about interchange fees and what does it mean for public policy? : commentary on Evans and Schmalensee
Debit cards ; Credit cards
A Markovian model for assessment of personnel hiring plans
As a result of the current economic environment, many organizations are having to operate with fewer resources. In the manpower area, these constraints have forced organizations to operate within well-defined hiring plans. Exceeding personnel ceilings is in most cases an intolerable situation. A mathematical model, based on the theory of Markov processes, is presented which can be used to assess the chances of success of personnel hiring plans. The model considers a plan to be successful if the final population size, at the end of the planning period, lies within a range specified by management. Although this model was developed to assess personnel hiring plans at the Goddard Space Flight Center, it is directly applicable wherever personnel hiring plans are used
Temperature reducing coating for metals subject to flame exposure Patent
Anodizing method for providing metal surfaces with temperature reducing coatings against flame
Long and Short GRB
We report evidence from the 3B Catalogue that short (T_90 < 10 s) and long
(T_90 > 10 s) GRB represent different populations and processes: Their spectral
behavior is qualitatively different, with short bursts harder in the BATSE
range, but chiefly long bursts detected at higher photon energies; \langle
V/V_max \rangle = 0.385 \pm 0.019 for short GRB but \langle V/V_max \rangle =
0.282 \pm 0.014 for long GRB, differing by 0.103 \pm 0.024. Long GRB may be the
consequence of accretion-induced collapse, but this mechanism fails for short
GRB, for which we suggest colliding neutron stars.Comment: 5 pp., latex, no figures, revised to work around bug in latex
compile
Aggregation of metallochlorophylls - Examination by spectroscopy
Nuclear magnetic resonance measurements determine which metallochlorophylls, besides magnesium-containing chlorophylls, possess coordination aggregation properties. Infrared spectroscopy reveals that only zinc pheophytin and zinc methyl pheophorbide showed significant coordination aggregation, whereas divalent nickel and copper did not
Application of advanced on-board processing concepts to future satellite communications systems: Bibliography
Abstracts are presented of a literature survey of reports concerning the application of signal processing concepts. Approximately 300 references are included
Innovation, Rent Extraction, and Integration in Systems Markets
We consider innovation incentives in markets where final goods comprise two strictly complementary components, one of which is monopolized. We focus on the case in which the complementary component is competitively supplied, and in which innovation is important. We explore ways in which the monopoly may have incentives to confiscate efficiency rents in the competitive sector, thus weakening or destroying incentives for independent innovation. We discuss how these problems are affected if the monopolist integrates into the competitive sector.
Application of CFD techniques toward the validation of nonlinear aerodynamic models
Applications of Computational fluid dynamics (CFD) methods to determine the regimes of applicability of nonlinear models describing the unsteady aerodynamic responses to aircraft flight motions are described. The potential advantages of computational methods over experimental methods are discussed and the concepts underlying mathematical modeling are reviewed. The economic and conceptual advantages of the modeling procedure over coupled, simultaneous solutions of the gasdynamic equations and the vehicle's kinematic equations of motion are discussed. The modeling approach, when valid, eliminates the need for costly repetitive computation of flow field solutions. For the test cases considered, the aerodynamic modeling approach is shown to be valid
Solution to the differential equation for combined radiative and convective cooling for a heated sphere
A solution is presented for the differential equation relating the combined effects of radiative and forced convective cooling for a heated sphere. The equation has the form where T and t are the variables temperature and time, respectively, and K sub o, T sub o, and H are constants. The solution can be used as a guideline for the design and understanding of space processing phenomena
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