Search results for "MULTIPLE"
showing 10 items of 2678 documents
The UWB-OFDM Channel Analysis in Frequency
2009
In this paper, the ultra-wideband channel with orthogonal frequency division multiplexing (UWB-OFDM) is analyzed in the frequency domain. For UWB-OFDM channels with log-normal fading in the time domain, we show that the amplitude of each subcarrier can be approximated by a Nakagami-m random variable, where the fading parameter, the mean power and the correlation coefficient are expressed in terms of the following parameters: time arrival of the clusters, inter-arrival time of rays inside clusters, and power decay constants of rays and clusters.
Topology of multiplex heterogeneous networks of Hodgkin-Huxley-type of models with bistability leading to stabilization stable equilibrium
2021
The dynamics of a multiplex heterogeneous networks of oscillators is studied. Two types of very similar models based on the Hodgkin-Huxley formalism are used as the basic elements of the network: the first one demonstrates bursting oscillations; the second one manifests bistability between bursting oscillations and stable equilibrium. Multiplex networks were developed and investigated, assuming more active communication between models with bistability. Different topologies of the networks are studied. It is shown that in this case it is enough to have one element with bistability in the subnetworks in order to stabilize the equilibrium state in the entire network.
Measuring charge based quantum bits by a superconducting single-electron transistor
2002
Single-electron transistors have been proposed to be used as a read-out device for Cooper pair charge qubits. Here we show that a coupled superconducting transistor at a threshold voltage is much more effective in measuring the state of a qubit than a normal-metal transistor at the same voltage range. The effect of the superconducting gap is to completely block the current through the transistor when the qubit is in the logical state 1, compared to the mere diminishment of the current in the normal-metal case. The time evolution of the system is solved when the measuring device is driven out of equilibrium and the setting is analysed numerically for parameters accessible by lithographic alu…
Fingerprints of spin-orbital polarons and of their disorder in the photoemission spectra of doped Mott insulators with orbital degeneracy
2017
We explore the effects of disordered charged defects on the electronic excitations observed in the photoemission spectra of doped transition metal oxides in the Mott insulating regime by the example of the $R_{1-x}$Ca$_x$VO$_3$ perovskites, where $R=$La,$\dots$,Lu. A fundamental characteristic of these vanadium $d^2$ compounds with partly filled $t_{2g}$ valence orbitals is the persistence of spin and orbital order up to high doping, in contrast to the loss of magnetic order in high-$T_c$ cuprates at low defect concentration. We demonstrate that the disordered electronic structure of doped Mott-Hubbard insulators can be obtained with high precision within the unrestricted Hartree-Fock appro…
Transverse nonlinear optics in heavy-metal-oxide glass
2008
6 pags. ; 9 figs.
Optical demultiplexing of millimeter-wave subcarriers for wireless channel distribution employing dual wavelength FBGs
2007
An optical mm-wave demultiplexer is presented. Double sideband modulation with suppressed optical carrier and filtering properties of dual overwritten fiber Bragg gratings are the fundamentals for optical demultiplexing of mm-wave radio-on-fiber signals: using a single optical carrier, Millimeter-wave signals of 20 and 40 GHz frequencies carrying independent data are created, transmitted over fiber, demultiplexed and wireless distributed to be detected and data recovered in a mobile unit. Double sideband modulation with suppressed optical carrier yields no power penalty due to chromatic dispersion, while the filtering properties of the dual overwritten fiber Bragg gratings allow less than −…
Two-dimensional optical wavelet decomposition with white-light illumination by wavelength multiplexing
2001
We present a novel method for achieving in real time a two-dimensional optical wavelet decomposition with white-light illumination. The underlying idea of the suggested method is wavelength multiplexing. The information in the different wavelet components of an input object is transmitted simultaneously in different wavelengths and summed incoherently at the output plane. Experimental results show the utility of the new proposed method.
Experimental Stark-broadening studies of the NI multiplet $\mathsf{(^{1}D) 3s^{2}D - (^{1}D)3p^{2}P^{o}}$ at 7904.5 �
2004
Experimental Stark-broadening studies of the NI multiplet $(^{1}{\rm D})3s$ $^{2}{\rm D} - (^{1}{\rm D})3p$ $^{2}{\rm P}^{\rm o}$ are reported. Line shape measurements were performed using a wall-stabilized arc operated at atmospheric pressure in helium with small amounts of nitrogen and hydrogen. The radiation of the plasma emitted from nearly homogeneous plasma layers in end-on direction was measured using a grating spectrometer equipped with a charge-coupled device (CCD) detector. The arc current was varied from 35 to 50 A in order to obtain different plasma conditions (electron densities and temperatures). The so-called j(x) profiles of Griem, convoluted with the corresponding Doppler a…
MultiChannel Multiple Scattering Theory for XAFS. Application to L2,3 Edges of Ca
2005
We present a multichannel extension of the multiple scattering method for x-ray absorption fine structure (XAFS) spectroscopy that allows to take account of atomic multiplet-like electron correlation effects in condensed systems, on the basis of ab initio electron structure calculations. The formalism is outlined and an application to near-edge XAFS at the L2,3 edges of Ca metal is presented. In this system, the experimentally observed branching ratio deviates strongly from that obtained from the standard (one-electron) approach to XAFS. This is due to that fact that one-electron theory neglects the multiplet coupling between the photo-electron and the 2p core-hole. Within the multi-channel…
The master two-loop two-point function. The general case
1991
Abstract We present a new calculation of the two-loop two-point function. Avoiding standard techniques such as Feynman parametrization and Wick rotation we end up with a simple double integral representation valid for arbitrary mass-cases. Numerical and analytical checks confirm our result.