1,344 research outputs found
Multi-beam Energy Moments of Multibeam Particle Velocity Distributions
High resolution electron and ion velocity distributions, f(v), which consist
of N effectively disjoint beams, have been measured by NASA's Magnetospheric
Multi-Scale Mission (MMS) observatories and in reconnection simulations.
Commonly used standard velocity moments generally assume a single
mean-flow-velocity for the entire distribution, which can lead to
counterintuitive results for a multibeam f(v). An example is the (false)
standard thermal energy moment of a pair of equal and opposite cold particle
beams, which is nonzero even though each beam has zero thermal energy. By
contrast, a multibeam moment of two or more beams has no false thermal energy.
A multibeam moment is obtained by taking a standard moment of each beam and
then summing over beams. In this paper we will generalize these notions,
explore their consequences and apply them to an f(v) which is sum of
tri-Maxwellians. Both standard and multibeam energy moments have coherent and
incoherent forms. Examples of incoherent moments are the thermal energy
density, the pressure and the thermal energy flux (enthalpy flux plus heat
flux). Corresponding coherent moments are the bulk kinetic energy density, the
RAM pressure and the bulk kinetic energy flux. The false part of an incoherent
moment is defined as the difference between the standard incoherent moment and
the corresponding multibeam moment. The sum of a pair of corresponding coherent
and incoherent moments will be called the undecomposed moment. Undecomposed
moments are independent of whether the sum is standard or multibeam and
therefore have advantages when studying moments of measured f(v).Comment: 27 single-spaced pages. Three Figure
The range of V - R colors for a cluster of E and S0 galaxies as a function of redshift
The expected (V - R) color distribution for a centrally condensed, relaxed cluster of E and S0 galaxies has been calculated as a function of redshift. Because of the differences in the ultraviolet spectra of E and S0 galaxies, which are correlated with absolute magnitude, the spread in (V - R) colors for such a cluster becomes increasingly wide for increasing redshift. This effect becomes pronounced for redshifts of 0.4 and beyond. Thus evidence for the color evolution of cluster galaxies will be seen as an additional broadening of the color distribution
A Comparison of Photointerpretive and Digital Production Methods for Four Key Remote Sensing-Based Information Products
No abstract availabl
Prolongations of Geometric Overdetermined Systems
We show that a wide class of geometrically defined overdetermined semilinear
partial differential equations may be explicitly prolonged to obtain closed
systems. As a consequence, in the case of linear equations we extract sharp
bounds on the dimension of the solution space.Comment: 22 pages. In the second version, a comparison with the classical
theory of prolongations was added. In this third version more details were
added concerning our construction and especially the use of Kostant's
computation of Lie algebra cohomolog
Program on stimulating operational private sector use of Earth observation satellite information
Ideas for new businesses specializing in using remote sensing and computerized spatial data systems were developd. Each such business serves as an 'information middleman', buying raw satellite or aircraft imagery, processing these data, combining them in a computer system with customer-specific information, and marketing the resulting information products. Examples of the businesses the project designed are: (1) an agricultural facility site evaluation firm; (2) a mass media grocery price and supply analyst and forecaster; (3) a management service for privately held woodlots; (4) a brokerage for insulation and roofing contractors, based on infrared imagery; (5) an expanded real estate information service. In addition, more than twenty-five other commercially attractive ideas in agribusiness, forestry, mining, real estate, urban planning and redevelopment, and consumer information were created. The commercial feasibility of the five business was assessed. This assessment included market surveys, revenue projections, cost analyses, and profitability studies. The results show that there are large and enthusiastic markets willing to pay for the services these businesses offer, and that the businesses could operate profitably
Observations of magnetic flux ropes during magnetic reconnection in the Earth's magnetotail
We present an investigation of magnetic flux ropes observed by the four
Cluster spacecraft during periods of magnetic reconnection in the Earth's
magnetotail. Using a list of 21 Cluster encounters with the reconnection
process in the period 2001–2006 identified in Borg et al. (2012), we present
the distribution and characteristics of the flux ropes. We find 27 flux ropes
embedded in the reconnection outflows of only 11 of the 21 reconnection
encounters. Reconnection processes associated with no flux rope observations
were not distinguishable from those where flux ropes were observed. Only 7 of
the 27 flux ropes show evidence of enhanced energetic electron flux above
50 keV,
and there was no clear signature of the flux rope in the thermal particle
measurements. We found no clear correlation between the flux rope core field
and the prevailing IMF <I>B</I><sub>y</sub> direction
ÄŒerenkov emission of quasiparallel whistlers by fast electron phase-space holes during magnetic reconnection
A correlation between infrared excess and period for Mira variables
The [8.7]-[11.4] infrared color is found to increase monotonically with increasing period for a sample of 41 Mira variables. We conclude that mass loss is not a stochastic process and that for any Mira variable the rate of mass loss is directly linked to the parameters which dictate the period of that variable
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