نتایج جستجو برای: oscillating magnetic field
تعداد نتایج: 1054791 فیلتر نتایج به سال:
We derive the closed system of averaged magnetohydrodynamic (MHD) equations for general oscillating flows. The used small parameter of our asymptotic theory is the dimensionless inverse frequency, and the leading term for a velocity field is chosen to be purely oscillating. The employed mathematical approach combines the twotiming method and the notion of a distinguished limit. The properties o...
in order to study the effect of intensity and exposure duration magnetic field on wheat (triticum aestivum l.) seed germination an experiment was conducted in laboratory of ferdowsi university of mashhad, iran. the experiment was including 11 treatments as three level of magnetic field intensities (pretreatment of seeds with 50, 100 and 150 mt magnetic field) and three exposure durations (10, 2...
Functional MRI has become an important tool of researchers and clinicians who seek to understand patterns of neuronal activation that accompany sensory and cognitive processes. However, the interpretation of fMRI images rests on assumptions about the relationship between neuronal firing and hemodynamic response that are not firmly grounded in rigorous theory or experimental evidence. Further, t...
The stability of a viscoelastic interface acted upon by an oscillating azimuthal magnetic field is studied. The interface separates two rigid magnetic fluid columns. Only azimuthal disturbrance modes are considered in a linear perturbation technique. Weak viscoelastic effects are taken into consideration, so that their contributions are demonstrated in the boundary conditions. The presence or a...
We study by Monte Carlo techniques the evolution of finite two-dimensional Ising systems in oscillating magnetic fields. The phenomenon of stochastic resonance is observed. The characteristic peak obtained for the correlation function between the external field and magnetization, versus the temperature of the system, is studied for various external fields and lattice sizes. PACS number(s): 05.4...
We have obtained a time series of 81 high-cadence circular polarization observations of the rapidly oscillating Ap star HD 24712 with the new ESPaDOnS spectropolarimeter at CFHT. We used the high-S/N, high-resolution Stokes I and V spectra to investigate possible variation of the mean longitudinal field over the pulsation cycle in this roAp star. Our multiline magnetic field and radial velocity...
The question of how, and how fast, magnetization can be reversed is a topic of great practical interest for the manipulation and storage of magnetic information. It is generally accepted that magnetization reversal should be driven by a stimulus represented by time-non-invariant vectors such as a magnetic field, spin-polarized electric current, or cross-product of two oscillating electric field...
S U M M A R Y The secular variation of the geomagnetic field is due to flow of molten iron in the Earth’s core. One can invert for the flow at the core-surface, assuming that the magnetic field is frozen into the core fluid. The validity of the frozen flux approximation (FFA) depends on the scale length of the magnetic field and the period of core motions. A first-order quantitative assessment ...
The equations for fully compressible rotating magnetoconvection are numerically solved in a Cartesian box assuming conditions roughly suitable for the geodynamo. The mean electromotive force describing the generation of mean magnetic flux by convective turbulence in the rotating fluid is directly calculated from the simulations, and the corresponding α-coefficients are derived. Due to the very ...
An electric current flowing around a loop produces a magnetic field and hence a magnetic flux through the loop. The ratio of the magnetic flux to the electric current is called the magnetic self-inductance. Can there be a dual situation with a magnetic current flowing around a loop and producing an electric field and hence an electric flux through the loop? Following the classical electrodynami...
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