Nuclear spin polarization can be pumped into spin-blockaded quantum dots by multiple Landau-Zener passages through singlet-triplet anticrossings. By numerical simulations of realistic systems with 10(7) nuclear spins during 10(5) sweeps, we uncover a mechanism of dynamical self-quenching which results in a fast saturation of the nuclear polarization under stationary pumping. This is caused by s...

Recent progress in the theory of solar and stellar dynamos is reviewed. Particular emphasis is placed on the mean-field theory which tries to describe the collective behavior of the magnetic field. In order to understand solar and stellar activity, a quantitatively reliable theory is necessary. Much of the new developments center around magnetic helicity conservation which is seen to be importa...

the micro-segregation in binary al-cu alloys containing 2.2, 3.7, and 4.8 wt.% copper was investigated by differential thermal analysis (dta) and numerical modeling. for this purpose, the alloys were melted using a dta furnace with the capability of quenching samples during solidification. the melted samples were cooled at 0.008 and 0.083 k/s and subsequently quenched from predetermined tempera...

Problem of high PT suppression in RHIC data is generally associated to jet quenching in a dense medium. We recently proposed a new approach to high energy nuclear scattering, which treats the initial stage of heavy ion collisions in a sophisticated way, and whose numerical solution is the model neXus. Within this model, there is no jet quenching, but the explicit energy conservation leads to si...

We report, for the first time to our knowledge, the presence of concentration-induced nonuniform power in tunable erbium-doped fiber lasers. A theoretical model is proposed with pair-induced quenching taken into account. We obtain good agreement between numerical and experimental results of a high-concentration erbium-doped fiber ring laser with a large tuning range of over 100 nm. These findin...

In this paper, we study the semidiscrete approximation of solution a nonlinear diffusion equation with source and singular boundary flux. We find some conditions under which form quenches in finite time estimate its quenching time. also establish convergence to theoretical one when mesh size tends zero. Finally, give numerical experiments for best illustration our analysis.

In this study the Taguchi method, has been applied to optimize the heat treatment parameters for the corrosion resistance of AA6061 aluminum alloy. The experimental design consisted of four parameters (aging temperature, aging time, quenching environment and NaCl concentration), each containing three levels. Tafel polarization measurements were carried out to determine the corrosion resistance ...