14,125 research outputs found
Collection and dissemination of TES system information for the paper and pulp industry
A survey of U.S. and international paper and pulp mills using thermal energy storage (TES) systems as a part of their production processes was conducted to obtain sufficient operating data to conduct a benefits analysis encompassing: (1) an energy conservation assessment, (2) an economic benefits analysis, and (3) an environmental impact assessment. An information dissemination plan was then proposed to effectively present the benefits of TES to the U.S. paper and pulp industry
Effective forces between colloids at interfaces induced by capillary wave-like fluctuations
We calculate the effective force mediated by thermally excited capillary
waves between spherical or disklike colloids trapped at a fluid interface. This
Casimir type interaction is shown to depend sensitively on the boundary
conditions imposed at the three-phase contact line. For large distances between
the colloids an unexpected cancellation of attractive and repulsive
contributions is observed leading to a fluctuation force which decays
algebraically very rapidly. For small separations the resulting force is rather
strong and it may play an important role in two-dimensional colloid aggregation
if direct van der Waals forces are weak.Comment: 7 pages, 3 figures, minor revisions, one additional figur
The valvula cerebelli of the spiny eel, Macrognathus aculeatus, receives primary lateral-line afferents from the rostrum of the upper jaw
In the spiny eel, Macrognathus aculeatus, anterodorsal and (to a lesser degree) anteroventral lateralline nerves project massively to the granular layer of the valvula cerebelli, throughout its rostrocaudal extent. The posterior lateral-line nerve terminates in the corpus cerebelli. Thus, valvula and corpus cerebelli are supplied with mechanosensory input of different peripheral origins. An analysis of the taxonomic distribution of experimentally determined primary lateral-line input to the three parts of the teleostean cerebellum reveals that the eminentia granularis always receives such input, and that the corpus cerebelli is the recipient of primary lateral-line input in many teleosts. The valvula, however, receives primary lateral-line afferents in only two examined species. In M. aculeatus, the massive lateral-line input to the valvula probably originates in mechanoreceptors located in the elongated rostrum of the upper jaw, a characteristic feature of mastacembeloid fishes. This projection to the valvula may therefore represent a unique specialization that arose with the evolution of the peculiar rostrum
Comparison of the noise characteristics of two low pressure ratio fans with a high throat Mach number inlet
Acoustics data obtained in experiments with two low pressure ratio 50.8 cm (20 in.) diameter model fans differing in design tip speed were compared. Determination of the average throat Mach number used to compare high Mach inlet noise reduction characteristics was based on a correlation of inlet wall static pressure measurements with a flow field calculation. The largest noise reductions were generally obtained with the higher tip speed fan. At a throat Mach number of 0.79, the difference in noise reduction was about 3.5 db with static test conditions. Although the noise reduction increased for the lower tip speed fan with a simulated flight velocity of 41 m/sec (80 knots), it was still about 2 db less than that of the high tip speed fan which was only tested at the static condition. However, variations in acoustic performance could not be absolutely attributed to the different fan designs because of differences in inlet lip contours which resulted in small variations of peak wall Mach number and axial extend of supersonic and near-sonic flow
Simulated flight effects on noise characteristics of a fan inlet with high throat Mach number
An anechoic wind tunnel experiment was conducted to determine the effects of simulated flight on the noise characteristics of a high throat Mach number fan inlet. Comparisons were made with the performance of a conventional low throat Mach number inlet with the same 50.8 cm fan noise source. Simulated forward velocity of 41 m/sec reduced perceived noise levels for both inlets, the largest effect being more than 3 db for the high throat Mach number inlet. The high throat Mach number inlet was as much as 7.5 db quieter than the low throat Mach number inlet with tunnel airflow and about 6 db quieter without tunnel airflow. Effects of inlet flow angles up to 30 deg were seemingly irregular and difficult to characterize because of the complex flow fields and generally small noise variations. Some modifications of tones and directivity at blade passage harmonics resulting from inlet flow angle variation were noted
Critical adsorption and critical Casimir forces for geometrically structured confinements
We study the behavior of fluids, confined by geometrically structured
substrates, upon approaching a critical point at T = Tc in their bulk phase
diagram. As generic substrate structures periodic arrays of wedges and ridges
are considered. Based on general renormalization group arguments we calculate,
within mean field approximation, the universal scaling functions for order
parameter profiles of a fluid close to a single structured substrate and
discuss the decay of its spatial variation into the bulk. We compare the excess
adsorption at corrugated substrates with the one at planar walls. The
confinement of a critical fluid by two walls generates effective critical
Casimir forces between them. We calculate corresponding universal scaling
functions for the normal critical Casimir force between a flat and a
geometrically structured substrate as well as the lateral critical Casimir
force between two identically patterned substrates.Comment: 25 pages, 21 figure
Implications of Quasar Black Hole Masses at High Redshifts
We investigated a sample of 15 luminous high-redshift quasars (3.3 < z < 5.1)
to measure the mass of their super-massive black holes (SMBH) and compare, for
the first time, results based on CIV, MgII, and Hbeta emission lines at
high-redshifts. Assuming gravitationally bound orbits as dominant broad-line
region gas motion, we determine black hole masses in the range of M_bh = 2
times 10^8 M_sun up to M_bh = 4 times 10^10 M_sun. While the black hole mass
estimates based on CIV and Hbeta agree well, MgII typically indicates a factor
of lower SMBH masses. A flatter slope of the Hbeta radius -
luminosity relation, a possibly steeper slope of the MgII radius - luminosity
relation, and a slightly larger radius of the MgII BLR than for Hbeta could
relax the discrepancy. In spite of these uncertainties, the CIV, MgII, and
Hbeta emission lines consistently indicate super-massive black hole masses of
several times 10^9 M_sun at redshifts up to z = 5.1. Assuming logarithmic
growth by spherical accretion with a mass to energy conversion efficiency of
epsilon = 0.1 and an Eddington ratio L_bol / L_edd calculated for each quasar
individually, we estimate black hole growth-times of the order of several ~100
Myr which are smaller than the age of the universe at the corresponding
redshift. Assuming high-mass seed black holes (M_bh^seed = 10^3 to 10^5 M_sun)
the SMBHs in the z = 3.5 quasars began to grow at redshifts z > 4, while for
the quasars with z > 4.5 they started at z = 6 to 10. These estimated time
scales for forming SMBHs at high redshifts, together with previous studies
indicating high quasar metallicities, suggest that the main SMBH growth phase
occurs roughly contemporaneously with a period of violent and extensive star
formation in proto-galactic nuclei.Comment: 26 pages, 4 figures. ApJ, accepted, Vol.611 (Aug20
Slowly decaying classical fields, unitarity, and gauge invariance
In classical external gauge fields that fall off less fast than the inverse
of the evolution parameter (time) of the system the implementability of a
unitary perturbative scattering operator (-matrix) is not guaranteed,
although the field goes to zero. The importance of this point is exposed for
the counter-example of low-dimensionally expanding systems. The issues of gauge
invariance and of the interpretation of the evolution at intermediate times are
also intricately linked to that point.Comment: 8 pages, no figure
Melting Pattern of Diquark Condensates in Quark Matter
Thermal color superconducting phase transitions in high density three-flavor
quark matter are investigated in the Ginzburg-Landau approach. Effects of
nonzero strange quark mass, electric and color charge neutrality, and direct
instantons are considered. Weak coupling calculations show that an interplay
between the mass and electric neutrality effects near the critical temperature
gives rise to three successive second-order phase transitions as the
temperature increases: a modified color-flavor locked (mCFL) phase (ud, ds, and
us pairings) -> a ``dSC'' phase (ud and ds pairings) -> an isoscalar pairing
phase (ud pairing) -> a normal phase (no pairing). The dSC phase is novel in
the sense that while all eight gluons are massive as in the mCFL phase, three
out of nine quark quasiparticles are gapless.Comment: minor changes in the text, fig.2 modifie
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