134,767 research outputs found
A high-Q^2 measurement of the photon structure function F_2^gamma at LEP2
The photon structure function F_2^gamma has been measured at of 706
GeV^2, using a sample of two-photon events with a scattered electron observed
in the OPAL electromagnetic endcap calorimeter. The data were taken during the
years 1997-1999, when LEP operated at e+e- centre-of-mass energies ranging from
183 to 202 GeV, and correspond to an integrated luminosity of 424 pb^-1. This
analysis represents the highest measurement of F_2^gamma made to date.Comment: 6 pages, 3 figures, To appear in the proceedings of Photon 2000,
Ambleside, Englan
Measurements of hadronic structure functions of the photon at LEP
The present status of the measurements of hadronic structure functions of the
photon, investigated in deep inelastic electron-photon scattering at LEP, is
presented. This article covers the hadronic structure function F_2^gamma of
quasi-real photons as well as the structure function of virtual photons.
Special emphasis is given to new developments in the analysis and to the most
recent measurements.Comment: 6 pages, 4 figures, To appear in the proceedings of DIS 2001,
Bologna, Ital
Turbulence measurements in the compressor exit flow of a General Electric CF6-50 engine
Ruggedized cooled film probes were used to measure CF6-50 compressor exit turbulence properties at three different engine idle condition test points. The turbulence probe was coupled to a constant temperature anemometer and signal conditioning system. An on-line readout system connected to the anemometer was used to check the data as it was acquired. At engine idle conditions, the turbulence intensity ranged from 4.8 percent to 5.6 percent and the length scale ranged from 5.64 cm to 6.95 cm. The length scale values are somewhat larger than the passage height at the measurement plane (5.54 cm), which indicates that the shape of the turbulent eddies are elongated in the axial direction. The microscale values range from about 0.73 cm to about 0.98 cm. Power spectral density distributions show that a large proportion of the turbulent energy at the measurement plane is concentrated at frequencies below one kilohertz
Mixed partial-wave scattering with spin-orbit coupling and validity of pseudo-potentials
We present exact solutions of two-body problem for spin-1/2 fermions with
isotropic spin-orbit(SO) coupling and interacting with an arbitrary short-range
potential. We find that in each partial-wave scattering channel, the
parametrization of two-body wavefunction at short inter-particle distance
depends on the scattering amplitudes of all channels. This reveals the mixed
partial-wave scattering induced by SO couplings. By comparing with results from
a square-well potential, we investigate the validity of original
pseudo-potential models in the presence of SO coupling. We find the s-wave
pseudo-potential provides a good approximation for low-energy solutions near
s-wave resonances, given the length scale of SO coupling much longer than the
potential range. However, near p-wave resonance the p-wave pseudo-potential
gives low-energy solutions that are qualitatively different from exact ones,
based on which we conclude that the p-wave model can not be applied to the
fermion system if the SO coupling strength is larger or comparable to the Fermi
momentum.Comment: 10 pages, 8 figures. Published version with figures improve
L-band, 1.2 m parabolic antenna-noise temperature measurement
Extensive antenna-noise temperature measurements at 1.6 GHz (L-band) were made using a 1.2 m (4 ft. diameter) parabolic dish antenna mounted on the flying bridge of a modern 15,690-ton, commercial-container ship. Both in-harbor and at-sea radiometer measurements were made that indicated a steady background, antenna-noise temperature value slightly less than 70 degrees Kelvin (K) at elevation angles of 5 percent, and greater, at 1.6 GHz. A comparison of theoretical and measured values indicate excellent agreement within about 5K for at-sea data. These measurements are helpful to RF equipment designers of maritime, L-band shipboard terminals for operation with the two, geostationary, maritime satellites, Marisat-A and -B
Navigation system and method
In a global positioning system (GPS), such as the NAVSTAR/GPS system, wherein the position coordinates of user terminals are obtained by processing multiple signals transmitted by a constellation of orbiting satellites, an acquisition-aiding signal generated by an earth-based control station is relayed to user terminals via a geostationary satellite to simplify user equipment. The aiding signal is FSK modulated on a reference channel slightly offset from the standard GPS channel. The aiding signal identifies satellites in view having best geometry and includes Doppler prediction data as well as GPS satellite coordinates and identification data associated with user terminals within an area being served by the control station and relay satellite. The aiding signal significantly reduces user equipment by simplifying spread spectrum signal demodulation and reducing data processing functions previously carried out at the user terminals
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Modular HLA RTI services: The GRIDS approach
The Generic Runtime Infrastructure for Distributed Simulation (GRIDS) has been developed to investigate modularity issues in distributed simulation. It could be argued that although the HLA RTI is a widespread solution to distributed simulation, it cannot include all possible services. This paper investigates an approach to extending the distributed simulation services available in the HLA RTI. One example of this is bridging support for HLA/DIS legacy integration. This paper therefore presents GRIDS, how GRIDS can be used to provide modular service support for the HLA RTI, and a case study on legacy integration to demonstrate our approach
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