282 research outputs found
A Magnetic-Field-Effect Transistor and Spin Transport
A magnetic-field-effect transistor is proposed that generates a
spin-polarized current and exhibits a giant negative magnetoresitance. The
device consists of a nonmagnetic conducting channel (wire or strip) wrapped, or
sandwiched, by a grounded magnetic shell. The process underlying the operation
of the device is the withdrawal of one of the spin components from the channel,
and its dissipation through the grounded boundaries of the magnetic shell,
resulting in a spin-polarized current in the nonmagnetic channel. The device
may generate an almost fully spin-polarized current, and a giant negative
magnetoresistance effect is predicted.Comment: 4 pages, 3 figure
trans-4-(2-Amino-5-bromo-6-methylpyrimidin-4-ylamino)-1-methylcyclohexanol
The title compound, C12H19BrN4O, represents the minor component of the two products obtained in a series of transformations involving the Grignard reaction of tert-butoxycarbonyl-protected 4-aminocyclohexanone with MeMgBr, and subsequent interaction of the obtained amino-substituted cyclohexanol with 4-chloro-6-methylpyrimidin-2-amine followed by bromination with N-bromosuccinimide. The X-ray structure showed that this product represents a trans isomer with respect to the amino and hydroxy substituents in the cyclohexyl ring; the dihedral angle between the aminopyrimidine plane and the (noncrystallographic) mirror plane of the substituted cyclohexyl fragment is 33.6 (3)°. Only two of the four potentially ‘active’ H atoms participate in intermolecular N—H⋯O and O—H⋯N hydrogen bonds, linking the molecules into layers parallel to the (10) plane
Fokker-Planck Equation with Fractional Coordinate Derivatives
Using the generalized Kolmogorov-Feller equation with long-range interaction,
we obtain kinetic equations with fractional derivatives with respect to
coordinates. The method of successive approximations with the averaging with
respect to fast variable is used. The main assumption is that the correlator of
probability densities of particles to make a step has a power-law dependence.
As a result, we obtain Fokker-Planck equation with fractional coordinate
derivative of order .Comment: LaTeX, 16 page
Secondary atomization of a biodiesel micro-emulsion fuel droplet colliding with a heated wall
Using high-speed video recording, we establish the following regimes of hydrodynami
Relaxation of high-energy quasiparticle distributions: electron-electron scattering in a two-dimensional electron gas
A theory is developed for the evolution of the non-equilibrium distribution
of quasiparticles when the scattering rate decreases due to particle
collisions. We propose a "modified one-collision approximation" which is most
effective for high-energy quasiparticle distributions. This method is used to
explain novel measurements of the non-monotonic energy dependence of the signal
of scattered electrons in a 2D system. The observed effect is related to a
crossover from the ballistic to the hydrodynamic regime of electron flow.Comment: 6 pages, 3 figure
Fractional Kinetics for Relaxation and Superdiffusion in Magnetic Field
We propose fractional Fokker-Planck equation for the kinetic description of
relaxation and superdiffusion processes in constant magnetic and random
electric fields. We assume that the random electric field acting on a test
charged particle is isotropic and possesses non-Gaussian Levy stable
statistics. These assumptions provide us with a straightforward possibility to
consider formation of anomalous stationary states and superdiffusion processes,
both properties are inherent to strongly non-equilibrium plasmas of solar
systems and thermonuclear devices. We solve fractional kinetic equations, study
the properties of the solution, and compare analytical results with those of
numerical simulation based on the solution of the Langevin equations with the
noise source having Levy stable probability density. We found, in particular,
that the stationary states are essentially non-Maxwellian ones and, at the
diffusion stage of relaxation, the characteristic displacement of a particle
grows superdiffusively with time and is inversely proportional to the magnetic
field.Comment: 15 pages, LaTeX, 5 figures PostScrip
Determination of aircraft current location on the basis of its acoustic noise
In this paper the algorithm of signal detection by means passive acoustics and digital data processing is proposed. This algorithm is original and contains the processing of signals, which are received by several acoustic aerials. For signal detection the calculation of wide-band ambiguity function together with its projection on time axis are used. All the calculations are executed with the real signals. As the result the location of the aircraft on Cartesian coordinate plane is observed. The suggested algorithm is also proposed to use for measuring of aircraft noise with the aim of environmental protection
Electron-beam propagation in a two-dimensional electron gas
A quantum mechanical model based on a Green's function approach has been used
to calculate the transmission probability of electrons traversing a
two-dimensional electron gas injected and detected via mode-selective quantum
point contacts. Two-dimensional scattering potentials, back-scattering, and
temperature effects were included in order to compare the calculated results
with experimentally observed interference patterns. The results yield detailed
information about the distribution, size, and the energetic height of the
scattering potentials.Comment: 7 pages, 6 figure
- …