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Nutation and precession resonances in an antiferromagnet subjected to a dc magnetic field are investigated by employing coupled linearized inertial Landau–Lifshitz–Gilbert equations describing the dynamics of magnetizations of antiferromagnet sublattices with uniaxial magnetocrystalline anisotropy. Analytical expressions for the eigenfrequencies of such an antiferromagnet are obtained for the longitudinal and transverse directions of the external dc field and for different ranges of its strength. The effect of inertia on the values of the resonant frequencies is shown for all possible states of the antiferromagnet in both the longitudinal and transverse directions of the external field. The estimated resonant frequencies are compared with those obtained from the numerical solution of the system of undamped inertial Landau–Lifshitz–Gilbert equations for closed trajectories of sublattice magnetizations. The good agreement of both independent estimations is demonstrated. [ABSTRACT FROM AUTHOR]

The nonlinear ac stationary responses of magnetization and the dynamic magnetic hysteresis of ferromagnetic particles with uniaxial anisotropy acted on by both external dc and ac magnetic fields are evaluated by employing the inertial Landau–Lifshitz–Gilbert equation. Analytical expressions are obtained for the components of the second- and third-order nonlinear susceptibility tensors using the perturbation method. The dynamic nonlinear susceptibility strongly depends on the dc field strength. The effect of inertia on the area and slope of the dynamic magnetic hysteresis loop is demonstrated. In addition to nutation resonance, the main nonlinear effects previously observed in the ferromagnetic resonance region (frequency doubling and appearance of weak subharmonic resonance peaks) are predicted in the nutation resonance frequency region. [ABSTRACT FROM AUTHOR]

Nutation and precession resonances are investigated for nanomagnets with uniaxial, biaxial, and cubic magnetocrystalline anisotropies employing the linearized inertial Landau–Lifshitz–Gilbert equation. Analytical expression analogous to the Smit–Beljers–Suhl formula for resonance frequencies is obtained. The estimated nutation resonance frequencies are compared with those obtained from the undamped inertial Landau–Lifshitz–Gilbert equation by determining numerically closed trajectories near the bottom of the deepest potential well. The good agreement of both independent estimations is demonstrated. [ABSTRACT FROM AUTHOR]

A study of heat transfer in simultaneously developing flow through rectangular tubes is presented in this article. Heat transfer coefficients were measured for three different tube sizes and shapes (D[sub h] = 2.21 mm, α = 0.050; D[sub h] = 3.02 mm, α = 0.108; and D[sub h ]= 1.74 mm, α = 0.029), which correspond to typical dimensions used in automotive heat exchangers. For each of these tubes, several different tube lengths were tested to measure the effect of developing flow on the Nusselt number. The results demonstrate that developing flow enhances Nusselt numbers, especially for short tubes. For the geometry range studied, the effect of aspect ratio was not very significant. Heat transfer correlations that accounted for the effects of Reynolds number (118 < Re < 10,671) Prandtl number (6.48 < Pr < 16.20), and bulk-to-wall property variations (0.243 < μ[sub b]/μ[sub w] < 0.630), and geometric features such as tube length, hydraulic diameter, and aspect ratio, were developed from the data. [ABSTRACT FROM AUTHOR]

Quantum effects in the Brownian motion in a tilted cosine potential are treated in the high temperature and weak bath-particle coupling limit via the semiclassical master equation for the time evolution of the reducedWigner function in phase space. The differential recurrence relation generated from the master equation by expanding the periodic Wigner function expressed as a function of wave number k in Fourier series via Floquet's theorem is solved for bounded periodic initial conditions using matrix-continued fractions yielding both the timeindependent and the time-dependent bounded periodic solutions. Just as the classical problem, the non-periodic solution is determined from the recurrence relation by integrating w.r.t. k over the first Brillouin zone with the initial conditions generated by the non-periodic Wigner distribution corresponding to zero probability current. The time-independent periodic (locked) solution is used to estimate quantum effects in the dc current-voltage characteristic of a Josephson junction including the capacitance, while the time-dependent nonperiodic (running) solution is used to determine the dynamic structure factor and ultimately via integration over the first Brillouin zone the lifetime of the zerovoltage state. The current-voltage characteristics displayed as average velocity versus tilt reproduce in the high damping limit those from the semiclassical Smoluchowski equation, while the decrease in the lifetime of the zero-voltage state due to (the barrier lowering) quantum effects appears to be very sensitive to the tilt. [ABSTRACT FROM AUTHOR]

Several corrections to the article "Master equation in phase space applied to the quantum Brownian motion in a tilted periodic potential" that was published on 12 April, 2012 issue are presented.