3,519 research outputs found
Entropy of spatial monopole currents in pure SU(2) QCD at finite temperature
We study properties of space-like monopole trajectories in the Maximal
Abelian gauge of quenched SU(2) QCD at the finite temperature. We concentrate
on infrared monopole clusters which are responsible for the confinement
properties of the theory. We determine numerically the effective action of the
monopoles projected onto the three-dimensional time-slice. Then we derive the
length distributions of the monopole loops and fix their entropy.Comment: 12 pages, 22 figures, RevTeX
Asynchronous vibration problem of centrifugal compressor
An unstable asynchronous vibration problem in a high pressure centrifugal compressor and the remedial actions against it are described. Asynchronous vibration of the compressor took place when the discharge pressure (Pd) was increased, after the rotor was already at full speed. The typical spectral data of the shaft vibration indicate that as the pressure Pd increases, pre-unstable vibration appears and becomes larger, and large unstable asynchronous vibration occurs suddenly (Pd = 5.49MPa). A computer program was used which calculated the logarithmic decrement and the damped natural frequency of the rotor bearing systems. The analysis of the log-decrement is concluded to be effective in preventing unstable vibration in both the design stage and remedial actions
Dark filaments observed at 8.3mm and 3.1mm wavelength
Mapping of the sun was made at 3.1mm (98 GHz) and 8.3mm (36 GHz) wavelengths with a 45m dish radio telescope at the Nobeyama Cosmic Radio Observatory. The depressions associated with large H alpha filaments are derived to be -0.2 at 8.3mm and -0.05 at 3.1mm, which are darker than the values inferred by Raoult et al. (1979
Observations of IRAS F10214+4724 at the Nobeyama millimeter array
F10214+4724 is an IRAS source at z=2.286 with L(sub FIR) approximately 10(exp 14) solar luminosity. The CO(3-2) emission was detected at the NRAO 12-m telescope, and its molecular gas mass was estimated to be (1-3)x10(exp 11) solar mass. This object is unique and important because it is the first high-z object from which molecular line emission is detected and it enables us to investigate molecular gas content, star forming material, at an early stage of galactic evolution. If IRAS F10214+4724 is a primeval galaxy at the formation process, it is possible the gas has not been collapsed yet to the galactic scale. On the other hand, it is also possible IRAS F10214+4724 is a merging or interacting system like the most of ultra-luminous infrared galaxies. However, since the first detection was made with a medium size single-dish telescope, the precise position, extent, and distribution of the molecular gas had not been determined. The aim of our aperture synthesis observations is therefore to determine position and distribution of molecular gas
Charge ordering in \theta-(BEDT-TTF)2RbZn(SCN)4: Cooperative effects of electron correlations and lattice distortions
Combined effects of electron correlations and lattice distortions are
investigated on the charge ordering in \theta-(BEDT-TTF)2RbZn(SCN)4
theoretically in a two-dimensional 3/4-filled extended Hubbard model with
electron-lattice couplings. It is known that this material undergoes a phase
transition from a high-symmetry metallic state to a low-symmetry insulating
state with a horizontal-stripe charge order (CO) by lowering temperature. By
means of the exact-diagonalization method, we show that electron-phonon
interactions are crucial to stabilize the horizontal-stripe CO and to realize
the low-symmetry crystal structure.Comment: 7 peges, 7 figures, accepted for publication in Phys. Rev.
Phase diagram of the one-dimensional half-filled extended Hubbard model
We study the ground state of the one-dimensional half-filled Hubbard model
with on-site (nearest-neighbor) repulsive interaction () and
nearest-neighbor hopping . In order to obtain an accurate phase diagram, we
consider various physical quantities such as the charge gap, spin gap,
Luttinger-liquid exponents, and bond-order-wave (BOW) order parameter using the
density-matrix renormalization group technique. We confirm that the BOW phase
appears in a substantial region between the charge-density-wave (CDW) and
spin-density-wave phases. Each phase boundary is determined by multiple means
and it allows us to do a cross-check to demonstrate the validity of our
estimations. Thus, our results agree quantitatively with the renormalization
group results in the weak-coupling regime (), with the
perturbation results in the strong-coupling regime (), and with
the quantum Monte Carlo results in the intermediate-coupling regime. We also
find that the BOW-CDW transition changes from continuous to first order at the
tricritical point and the BOW
phase vanishes at the critical end point .Comment: 4 pages, 5 figure
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