1,026 research outputs found
Photon-energy dissipation caused by an external electric circuit in "virtual" photo-excitation processes
We consider generation of an electrical pulse by an optical pulse in the
``virtual excitation'' regime. The electronic system, which is any
electro-optic material including a quantum well structure biased by a dc
electric field, is assumed to be coupled to an external circuit. It is found
that the photon frequency is subject to an extra red shift in addition to the
usual self-phase modulation, whereas the photon number is conserved. The Joule
energy consumed in the external circuit is supplied only from the extra red
shift.Comment: 4 pages, 1 fugur
Polarized Gluons in the Nucleon
QCD suggests that gluons in the nucleon play an important role in {\it
so-called} ``the proton spin problem''. In this talk, the behavior of the
polarized gluon distribution in the nucleon is discussed by using the
positivity condition of distribution functions together with the unpolarized
and polarized experimental data.Comment: LaTeX file, 9 pages+4 figures not included (available upon request),
Talk presented at the Workshop on GeV Scale Physics as a Probe into New
Physics, Toyama(Japan), 26-28 June, 199
Observation of Jonscher Law in AC Hopping Conduction of Electron-Doped Nanoporous Crystal 12CaO7Al2O3 in THz Frequency Range
We have performed terahertz time-domain spectroscopy of carrier-doped
nanoporous crystal 12CaO7Al2O3 showing the Mott variable range hopping at room
temperature. The real part of the dielectric constant clearly demonstrates the
nature of localized carriers. The frequency dependence of both the real and
imaginary parts of the dielectric constant can be simply explained by assuming
two contributions: a dielectric response by the parent compound with no
carriers and an AC hopping conduction with the Jonscher law generally reported
up to GHz range. The possible obedience to the Jonscher law in the THz range
suggests a relaxation time of the hopping carriers much faster than 1ps in the
carrier-doped 12CaO7Al2O3.Comment: 4pages 3figures. to be published in Phys. Rev.
Development and validation of new cryogenic cavitation model for rocket turbopump inducer
A rocket propellant is often used cryogenic fluid such as liquid hydrogen or liquid oxygen, and it is known that a suction performance of turbopump inducer (Fig.1) in cryogenic fluid is improved due to Thermodynamic effect . Thermodynamic effect can be explained by temperature decrease inside a cavity region arising from the latent heat absorption. Although this effect is also to be observed in water cavitation, it becomes more accentuated in cryogenic fluid. In order to properly understand the cavitation performance of the inducer, this thermodynamic effect should not be overlooked. In the present study, cryogenic cavitation model without energy equation was established. During the design phase of an inducer, wall clock time of CFD simulation becomes an important point, therefore, equation number should be small. The present model considers that temperature decrease due to latent heat absorption is analytically estimated. Validation calculations were carried out for blunt head form and hydrofoil for water cavitation and two-dimensional blunt body, Laval nozzle and inducer for cryogenic fluids.http://deepblue.lib.umich.edu/bitstream/2027.42/84260/1/CAV2009-final63.pd
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