Spring Changeover of the Middle Atmosphere Circulation Compared with Rocket Wind Data up to 80 Km

The middle atmosphere circulation is governed by two seasonal basic states in winter and summer, twice a year separated by relatively shortlived reversal periods. These seasonal basic states of circulation and the spring changeover period between them are investigated

Orbital photogalvanic effects in quantum-confined structures

We report on the circular and linear photogalvanic effects caused by free-carrier absorption of terahertz radiation in electron channels on (001)-oriented and miscut silicon surfaces. The photocurrent behavior upon variation of the radiation polarization state, wavelength, gate voltage and temperature is studied. We present the microscopical and phenomenological theory of the photogalvanic effects, which describes well the experimental results. In particular, it is demonstrated that the circular (photon-helicity sensitive) photocurrent in silicon-based structures is of pure orbital nature originating from the quantum interference of different pathways contributing to the absorption of monochromatic radiation.Comment: 8 pages, 5 figures, two culumne

Valley separation in graphene by polarized light

We show that the optical excitation of graphene with polarized light leads to the pure valley current where carriers in the valleys counterflow. The current in each valley originates from asymmetry of optical transitions and electron scattering by impurities owing to the warping of electron energy spectrum. The valley current has strong polarization dependence, its direction is opposite for normally incident beams of orthogonal linear polarizations. In undoped graphene on a substrate with high susceptibility, electron-electron scattering leads to an additional contribution to the valley current that can dominate.Comment: 4+ pages, 2 figure

ІНФОРМАЦІЙНЕ ЗАБЕЗПЕЧЕННЯ КОНТРОЛЮ ПОТОЧНОГО СТАНУ ІНФОКОМУНІКАЦІЙНОЇ МЕРЕЖІ В УМОВАХ ВПЛИВУ ЗОВНІШНІХ ЗАВАД

The processes of information support of situational management of infocommunication networks in the conditions of influence of external disturbances are considered in the work. The expediency of using the mathematical apparatus of information theory for the analysis of processes of control of parameters of infocommunication networks is substantiated. It is shown that periodic multiple sequential control of the parameters of the infocommunication network provides determination of the state of the network under the influence of external interference and the probability of its transition to a new state in the near future. The entropy of the controlled process changes with changing quantization step and multiple successive measurements. It is noted that in the case of periodic multiple consecutive control, the object is constantly in transition in terms of information. The entropy value of an object can be considered determined only for some short periods of time between measurements or when information about the object is not received. An important condition for improving the quality of control is to reduce and completely eliminate delays in the information process.The processes of information support of situational management of infocommunication networks in the conditions of influence of external disturbances are considered in the work. The expediency of using the mathematical apparatus of information theory for the analysis of processes of control of parameters of infocommunication networks is substantiated. It is shown that periodic multiple sequential control of the parameters of the infocommunication network provides determination of the state of the network under the influence of external interference and the probability of its transition to a new state in the near future. The entropy of the controlled process changes with changing quantization step and multiple successive measurements. It is noted that in the case of periodic multiple consecutive control, the object is constantly in transition in terms of information. The entropy value of an object can be considered determined only for some short periods of time between measurements or when information about the object is not received. An important condition for improving the quality of control is to reduce and completely eliminate delays in the information process

Photoexcitation of valley-orbit currents in (111)-oriented silicon metal-oxide-semiconductor field-effect transistors

We demonstrate the injection of pure valley-orbit currents in multivalley semiconductors and present the phenomenological theory of this effect. We studied photoinduced transport in (111)-oriented silicon metaloxide-semiconductor field effect transistors at room temperature. By shining circularly polarized light on exact oriented structures with six equivalent valleys, nonzero electron fluxes within each valley are generated, which compensate each other and do not yield a net electric current. By disturbing the balance between the valley fluxes, we demonstrate that the pure valley-orbit currents can be converted into a measurable electric current