153 research outputs found
Controlling the Spin Polarization of the Electron Current in a Semimagnetic Resonant-Tunneling Diode
The spin filtering effect of the electron current in a double-barrier
resonant-tunneling diode (RTD) consisting of ZnMnSe semimagnetic layers has
been studied theoretically. The influence of the distribution of the magnesium
ions on the coefficient of the spin polarization of the electron current has
been investigated. The dependence of the spin filtering degree of the electron
current on the external magnetic field and the bias voltage has been obtained.
The effect of the total spin polarization of the electron current has been
predicted. This effect is characterized by total suppression of the spin-up
component of electron current, that takes place when the Fermi level coincides
with the lowest Landau level for spin-up electrons in the RTD semimagnetic
emitter
First Principles Analysis of Electron-Phonon Interaction in Graphene
The electron-phonon interaction in monolayer graphene is investigated by
using density functional perturbation theory. The results indicate that the
electron-phonon interaction strength is of comparable magnitude for all four
in-plane phonon branches and must be considered simultaneously. Moreover, the
calculated scattering rates suggest an acoustic phonon contribution that is
much weaker than previously thought, revealing the role of optical phonons even
at low energies. Accordingly it is predicted, in good agreement with a recent
measurement, that the intrinsic mobility of graphene may be more than an order
of magnitude larger than the high values reported in suspended samples.Comment: 12 pages, 4 figure
Observations of comets C/2002 T7 (LINEAR) and 2P/Encke at Andrushivka
Photometric and spectral observations of C/2002 T7 (LINEAR) and 2P/Encke were made with the Zeiss-600 telescope at the Andrushivka Astronomical Observatory in November 2003. CCD imaging of the comets was carried out with narrowband HB filters CN, RC, and BC. The total number of CN molecules, gas production rate for CN, and Afρ value for the dust coma were obtained. The optical spectra of Comet C/2002 T7 (LINEAR) were obtained and reduced for the wavelength range 4200–7300 Å. The reddening gradient is derived for th
Psychosomatic organism disorders in peptic ulcer of the stomach and duodenum
Велику частину гастроентерологічних захворювань займає пептична виразка шлунку та дванадцятипалої кишки. Особливу роль у даному захворюванні відіграє психоемоційний стан пацієнта, особливо в умовах тотальної урбанізації, коли стресові фактори виключити із життя неможливо, що і призводять до психосоматичних захворювань
Electro-optical bunch length monitor for flute: Layout and simulations
A new compact linear accelerator FLUTE is currently under construction at Karlsruhe Institute of Technology (KIT) in collaboration with DESY and PSI. It aims at obtaining femtosecond electron bunches (~1fs - 300 fs) with a wide charge range (1 pC - 3 nC) and requires a precise bunch length diagnostic system. Here we present the layout of a bunch length monitor based on the electro-optic technique of spectral decoding using an Yb-doped fiber laser system (central wavelength 1030 nm) and a GaP crystal. Simulations of the electro-optic signal for different operation modes of FLUTE were performed and main challenges are discussed in this talk. This work is funded by the European Union under contract PITN-GA-2011-28919
FPGA-Implemented Fractal Decoder with Forward Error Correction in Short-Reach Optical Interconnects
Forward error correction (FEC) codes combined with high-order modulator formats, i.e., coded modulation (CM), are essential in optical communication networks to achieve highly efficient and reliable communication. The task of providing additional error control in the design of CM systems with high-performance requirements remains urgent. As an additional control of CM systems, we propose to use indivisible error detection codes based on a positional number system. In this work, we evaluated the indivisible code using the average probability method (APM) for the binary symmetric channel (BSC), which has the simplicity, versatility and reliability of the estimate, which is close to reality. The APM allows for evaluation and compares indivisible codes according to parameters of correct transmission, and detectable and undetectable errors. Indivisible codes allow for the end-to-end (E2E) control of the transmission and processing of information in digital systems and design devices with a regular structure and high speed. This study researched a fractal decoder device for additional error control, implemented in field-programmable gate array (FPGA) software with FEC for short-reach optical interconnects with multilevel pulse amplitude (PAM-M) modulated with Gray code mapping. Indivisible codes with natural redundancy require far fewer hardware costs to develop and implement encoding and decoding devices with a sufficiently high error detection efficiency. We achieved a reduction in hardware costs for a fractal decoder by using the fractal property of the indivisible code from 10% to 30% for different n while receiving the reciprocal of the golden ratio
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