102,210 research outputs found
Surface current excitation on an inhomogeneously-sheathed plasma immersed cylinder by electromagnetic and electrokinetic waves
Inhomogeneous sheath effect on surface current excitation of immersed plasma cylinder by electromagnetic and electrokinetic wave
Entropy for Quark States
We discuss the quantum state structure using the standard model for three
colored quarks in the fundamental representations of making up the
singlet ground state of the hadrons. This allows us to calculate a finite von
Neumann entropy from the quantum reduced density matrix, which we explicitly
evaluate for the quarks in a model for the meson and baryon states. Finally we
look into the general effects and implications of entanglement in the
color space.Comment: 9 pages, 0 figure
Conditions driving chemical freeze-out
We propose the entropy density as the thermodynamic condition driving best
the chemical freeze-out in heavy-ion collisions. Taking its value from lattice
calculations at zero chemical potential, we find that it is excellent in
reproducing the experimentally estimated freeze-out parameters. The two
characteristic endpoints in the freeze-out diagram are reproduced as well.Comment: 8 pages, 5 eps figure
Cross-calibration of Suzaku XIS and XMM-Newton EPIC using clusters of galaxies
We extend a previous cross-calibration study by the International
Astronomical Consortium for High Energy Calibration (IACHEC) on
XMM-Newton/EPIC, Chandra/ACIS and BeppoSAX/MECS X-ray instruments with clusters
of galaxies to Suzaku/XIS instruments. Our aim is to study the accuracy of the
energy-dependent effective area calibration of the XIS instruments by
comparison of spectroscopic temperatures, fluxes and fit residuals obtained
with Suzaku/XIS and XMM-Newton/EPIC-pn for the same cluster. The temperatures
measured in the hard 2.0-7.0 keV energy band with all instruments are
consistent within 5 %. However, temperatures obtained with the XIS instruments
in the soft 0.5-2.0 keV band disagree by 9-29 %. We investigated residuals in
the XIS soft band, which showed that if XIS0 effective area shape is accurately
calibrated, the effective areas of XIS1 and XIS3 are overestimated below 1.0
keV (or vice versa). Adjustments to the modelling of the column density of the
XIS contaminant in the 3-6 arcmin extraction region while forcing consistent
emission models in each instrument for a given cluster significantly improved
the fits. The oxygen column density in XIS1 and XIS3 contaminant must be
increased by 1-2E17 cm^-2 in comparison to the values implemented in the
current calibration, while the column density of the XIS0 contaminant given by
the analysis is consistent with the public calibration. XIS soft band
temperatures obtained with the modification to the column density of the
contaminant agree better with temperatures obtained with the EPIC-pn instrument
of XMM-Newton, than with those derived using the Chandra-ACIS instrument.
However, comparison of hard band fluxes obtained using Suzaku-XIS to fluxes
obtained using the Chandra-ACIS and EPIC-pn instruments proved inconclusive.Comment: 24 pages, 27 figures, accepted for publication in Astronomy &
Astrophysic
Space station particulate contamination environment
The origin of particulate contamination on the Space Station will mostly be from pre-launch operations. The adherence and subsequent release of these particles during space flight are discussed. Particle size, release velocity, and release direction are important in determining particle behavior in the vicinity of the vehicle. The particulate environment at the principal science instrument locations is compared to the space shuttle bay environment. Recommendations for possibly decreasing the particulate contamination are presented
The influence of strange quarks on QCD phase diagram and chemical freeze-out: Results from the hadron resonance gas model
We confront the lattice results on QCD phase diagram for two and three
flavors with the hadron resonance gas model. Taking into account the
truncations in the Taylor-expansion of energy density done on the
lattice at finite chemical potential , we find that the hadron resonance
gas model under the condition of constant describes very well the
lattice phase diagram. We also calculate the chemical freeze-out curve
according to the entropy density . The -values are taken from lattice QCD
simulations with two and three flavors. We find that this condition is
excellent in reproducing the experimentally estimated parameters of the
chemical freeze-out.Comment: 5 pages, 3 figures and 1 table Talk given at VIIIth international
conference on ''Strangeness in Quark Matter'' (SQM 2004), Cape Town, South
Africa, Sep. 15-20 200
Effect of the NACA Injection Impeller on the Mixture Distribution of a Double-Row Radial Aircraft Engine
The NACA injection impeller was developed to improve the mixture distribution of aircraft engines by discharging the fuel from a centrifugal supercharger impeller, thus promoting a thorough mixing of fuel and charge air. Tests with a double-row radial aircraft engine indicated that for the normal range of engine power the NACA injection impeller provided marked improvement in mixture distribution over the standard spray-bar injection system used in the same engine. The mixture distribution at cruising conditions was excellent; at 1200, 15OO, and 1700 brake horsepower, the differences between the fuel-air ratios of the richest and the leanest cylinders were reduced to approximately one-third their former values. The maximum cylinder temperatures were reduced about 30 [degrees] F and the temperature distribution was improved by approximately the
degree expected from the improvement in mixture distribution. Because the mixture distribution of the engine tested improves slightly at engine powers exceeding 1500 brake horsepower and because the effectiveness of the particular impeller diminished slightly at high rates of fuel flow, the improvement in mixture distribution at
rated power and rich mixtures was less than that for other conditions.
The difference between the fuel-air ratios of the richest and the leanest cylinders of the engine using the standard spray bar was so great that the fuel-air ratios of several cylinders were well below the chemically correct mixture, whereas other cylinders were operating at rich mixtures. Consequently, enrichment to improve engine cooling actually increascd some of the critical temperatures. The uniform mixture distribution providod by the injection impeller restored the normal response of cylinder temperatures to mixture enrichnent
Synchronized voltage contrast display analysis system
An apparatus and method for comparing internal voltage potentials of first and second operating electronic components such as large scale integrated circuits (LSI's) in which voltage differentials are visually identified via an appropriate display means are described. More particularly, in a first embodiment of the invention a first and second scanning electron microscope (SEM) are configured to scan a first and second operating electronic component respectively. The scan pattern of the second SEM is synchronized to that of the first SEM so that both simultaneously scan corresponding portions of the two operating electronic components. Video signals from each SEM corresponding to secondary electron signals generated as a result of a primary electron beam intersecting each operating electronic component in accordance with a predetermined scan pattern are provided to a video mixer and color encoder
Statistical derivation of design criteria for liquid rocket combustion instability Final report
Statistical correlation between engine design and combustion stability in liquid propellant rocket engine
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