Search results for "current"
showing 10 items of 2224 documents
The new results on lattice deformation of current algebra
2008
The topic “Quantum Integrable Models” was reviewed in the literature and presented to the conferences and schools many times. Only the reports of our own have been done on quite a few occasions (see, e.g., [1], [2]). So here we shall try to present a fresh approach to the description of the ingredients of construction of integrable models. It has gradually evolved in the process of our joint work. Whereas our goal was the Sugawara construction for the lattice affine algebra (known now as the St.Petersburg algebra), (see, e.g., [1]), some technical developments happen to be new and useful for the already developed subjects. Here we shall underline this development.
Current Algebras as Hilbert Space Operator Cocycles
1994
Aspects of a generalized representation theory of current algebras in 3 + 1 dimensions axe discussed. Rules for a systematic computation of vacuum expectation values of products of currents are described. Their relation to gauge group actions in bundles of fermionic Fock spaces and to the sesquilinear form approach of Langmann and Ruijsenaars is explained. The regularization for a construction of an operator cocycle representation of the current algebra is explained. An alternative formula for the Schwinger terms defining gauge group extensions is written in terms of Wodzicki residue and Dixmier trace.
Electromechanical Numerical Analysis of an Air-Core Pulsed Alternator via Equivalent Network Formulation
2017
In this paper, the numerical analysis on an air-core pulsed alternator is presented. Since compulsators are characterized by very fast electromechanical transients, their accurate analysis requires strong coupling between the equations governing the electrical and the mechanical behaviors. The device is investigated by using a dedicated numerical code capable to take into account eddy currents, compensating windings, as well as the excitation/control circuits. Furthermore, the code is capable of modeling centrifugal forces and vibrations acting on the shaft due to electric and mechanical unbalances or to misalignments of the shaft from its centered position. This makes the code a very power…
Sign Languages Recognition Based on Neural Network Architecture
2017
In the last years, many steps forward have been made in speech and natural languages recognition and were developed many virtual assistants such as Apple’s Siri, Google Now and Microsoft Cortana. Unfortunately, not everyone can use voice to communicate to other people and digital devices. Our system is a first step for extending the possibility of using virtual assistants to speech impaired people by providing an artificial sign languages recognition based on neural network architecture.
A procedure to evaluate the seven parameters of the two-diode model for photovoltaic modules
2019
Abstract The paper presents an analytical procedure to calculate the seven parameters of the two-diode model of photovoltaic (PV) panels for any value of the solar irradiance and cell temperature. Six parameters (the photocurrent, the diode reverse saturation currents, the quality factor of the first diode and the series and shunt resistances), are evaluated by solving the equations related to the properties of the main points of the current-voltage (I-V) characteristics. The further information, necessary to calculate the entire set of seven truly independent parameters, is based on two conditions that have to be simultaneously satisfied: 1) the exclusion of negative values of the model pa…
High-efficiency silicon-compatible photodetectors based on Ge quantum dots
2011
We report on high responsivity, broadband metal/insulator/semiconductor photodetectors with amorphous Ge quantum dots (a-Ge QDs) as the active absorbers embedded in a silicon dioxide matrix. Spectral responsivities between 1-4 A/W are achieved in the 500-900 nm wavelength range with internal quantum efficiencies (IQEs) as high as ∼700%. We investigate the role of a-Ge QDs in the photocurrent generation and explain the high IQE as a result of transport mechanisms via photoexcited QDs. These results suggest that a-Ge QDs are promising for high-performance integrated optoelectronic devices that are fully compatible with silicon technology in terms of fabrication and thermal budget. © 2011 Amer…
Theoretical study on the influence of electric field direction on the photovoltaic performance of aryl amine organic dyes for dye-sensitized solar ce…
2019
It is very important to reveal the influence of different electric field directions on dye sensitizers. Thus, in this study, we investigated the electronic structures and optical properties of six designed aryl amine organic dye models under different electric fields using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Moreover, the electronic structures and optical properties of these studied dyes with different electric field in tetrahydrofuran (THF) were also calculated. The key parameters of the short-circuit current density (Jsc), including light harvesting efficiency (LHE) and intra-molecular charge transfer (ICT), are discussed in detail. With …
Effect of Reynolds number and lithium cation insertion on titanium anodization
2016
This work studies the influence of using hydrodynamic conditions (Reynolds number, Re = 0 to Re = 600) during Ti anodization and Li+ intercalation on anatase TiO2 nanotubes. The synthesized photocatalysts were characterized by using Field Emission Scanning Electron Microscope (FE-SEM), Raman Confocal Laser Microscopy, Electrochemical Impedance Spectroscopy (EIS), Mott-Schottky analysis (M-S), photoelectrochemical hydrogen production and resistance to photocorrosion tests. The obtained results showed that the conductivity of the NTs increases with Li+ intercalation and Re. The latter is due to the fact that the hydrodynamic conditions eliminate part of the initiation layer formed over the tu…
Spin-orbit torque-driven magnetization switching and thermal effects studied in Ta\CoFeB\MgO nanowires
2014
We demonstrate magnetization switching in out-of-plane magnetized Ta\CoFeB\MgO nanowires by current pulse injection along the nanowires, both with and without a constant and uniform magnetic field collinear to the current direction. We deduce that an effective torque arising from spin-orbit effects in the multilayer drives the switching mechanism. While the generation of a component of the magnetization along the current direction is crucial for the switching to occur, we observe that even without a longitudinal field thermally generated magnetization fluctuations can lead to switching. Analysis using a generalized N\'eel-Brown model enables key parameters of the thermally induced spin-orbi…
Should TiO2 nanostructures doped with Li+ be used as photoanodes for photoelectrochemical water splitting applications?
2017
[EN] Different TiO2 nanostructures, nanotubes and nanosponges, were obtained by anodization of Ti under stagnant and hydrodynamic conditions. Samples were doped with Li+ before and after annealing at 450 degrees C during 1 h. The nanostructures were characterized by different microscopy techniques: Field Emission Scanning Electron Microscopy (FE-SEM) and Raman Confocal Laser Microscopy. Additionally, Incident Photon-to-electron Conversion Efficiency (IPCE), photoelectrochemical water splitting and stability measurements were also performed. According to the results, TiO2 nanostructures doped before annealing present the worst photocurrent response, even if compared with undoped samples. On …