128,558 research outputs found
Quadrature entanglement and photon-number correlations accompanied by phase-locking
We investigate quantum properties of phase-locked light beams generated in a
nondegenerate optical parametric oscillator (NOPO) with an intracavity
waveplate. This investigation continuous our previous analysis presented in
Phys.Rev.A 69, 05814 (2004), and involves problems of continuous-variable
quadrature entanglement in the spectral domain, photon-number correlations as
well as the signatures of phase-locking in the Wigner function. We study the
role of phase-localizing processes on the quantum correlation effects. The
peculiarities of phase-locked NOPO in the self-pulsing instability operational
regime are also cleared up. The results are obtained in both the
P-representation as a quantum-mechanical calculation in the framework of
stochastic equations of motion, and also by using numerical simulation based on
the method of quantum state diffusion.Comment: Subm. to PR
The breakage prediction for hydromechanical deep drawing based on local bifurcation theory
A criterion of sheet metal localized necking under plane stress was established based on the bifurcation theory and the characteristics theory of differential equation. In order to be capable to incorporate the directional dependence of the plastic strain rate on stress rate, Ito-Goya’s constitutive equation which gave a one to one relationship between stress rate component and plastic strain rate component was employed. The hydromechanical deep drawing process of a cylindrical cup part was simulated using the commercial software ABAQUS IMPLICIT. The onset of breakage of the part during the forming process was predicted by combining the simulation results with the local necking criterion. The proposed method is applied to the hydro-mechanical deep drawing process for A2219 aluminum alloy sheet metal to predict the breakage of the cylindrical cup part. The proposed method can be applied to the prediction of breakage in the forming of the automotive bodies
Conductivity and Atomic Structure of Isolated Multiwalled Carbon Nanotubes
We report associated high resolution transmission electron microscopy (HRTEM)
and transport measurements on a series of isolated multiwalled carbon
nanotubes. HRTEM observations, by revealing relevant structural features of the
tubes, shed some light on the variety of observed transport behaviors, from
semiconducting to quasi-metallic type. Non Ohmic behavior is observed for
certain samples which exhibit "bamboo like" structural defects. The resistance
of the most conducting sample, measured down to 20 mK, exhibits a pronounced
maximum at 0.6 K and strong positive magnetoresistance.Comment: 4 pages, 4 eps figure
Toward precision mass measurements of neutron-rich nuclei relevant to -process nucleosynthesis
The open question of where, when, and how the heavy elements beyond iron
enrich our Universe has triggered a new era in nuclear physics studies.\ Of all
the relevant nuclear physics inputs, the mass of very neutron-rich nuclides is
a key quantity for revealing the origin of heavy elements beyond iron.\
Although the precise determination of this property is a great challenge,
enormous progress has been made in recent decades, and it has contributed
significantly to both nuclear structure and astrophysical nucleosynthesis
studies.\ In this review, we first survey our present knowledge of the nuclear
mass surface, emphasizing the importance of nuclear mass precision in
-process calculations.\ We then discuss recent progress in various methods
of nuclear mass measurement with a few selected examples.\ For each method, we
focus on recent breakthroughs and discuss possible ways of improving the
weighing of -process nuclides.Comment: 10 figures, review articles in Frontiers of Physic
Giant dispersion of critical currents in superconductor with fractal clusters of a normal phase
The influence of fractal clusters of a normal phase on the dynamics of a
magnetic flux trapped in a percolative superconductor is considered. The
critical current distribution and the current-voltage characteristics of
fractal superconducting structures in the resistive state are obtained for an
arbitrary fractal dimension of the cluster boundaries. The range of fractal
dimensions, where the dispersion of critical currents becomes infinite, is
found. It is revealed that the fractality of clusters depresses of the electric
field caused by the magnetic flux motion thus increasing the critical current
value. It is expected that the maximum current-carrying capability of a
superconductor can be achieved in the region of giant dispersion of critical
currents.Comment: 7 pages with 3 figure
- …