6,166 research outputs found
Adaptive noise cancellation using multichannel lattice structure.
This thesis presents a multichannel adaptive noise cancellation technique (MCLS) for cancelling the noise over nonlinear transmission channel. The technique applies to the situation in which the reference signal and noisy primary signal are collected simultaneously. The coefficients of the multichannel multiple regression transversal filter are modified adaptively according to the backward prediction error vector generated from the multichannel adaptive lattice predictor. This multichannel adaptive noise cancellation procedure involves the NLMS adaptive algorithm. The performance of the new technique using different types of transmission channels, different types of reference inputs and different types of noise-free primary inputs are examined analytically. The new approach is experimentally shown to have better noise cancellation performance than the existing single-channel adaptive lattice noise cancellation algorithm (SCLS) over nonlinear transmission channel case, especially in low input SNR situation.Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2004 .X54. Source: Masters Abstracts International, Volume: 43-01, page: 0288. Adviser: H. K. Kwan. Thesis (M.A.Sc.)--University of Windsor (Canada), 2004
English Major Undergraduates’ Needs and Perceptions of Business English Activities and Resources in a Chinese University
This article explores English major undergraduates’ views on business English skills and topics, and investigates their perceptions of the meaningful activities and resources in one Chinese university context. The main research instruments are questionnaires containing rating and open-ended questions, and researcher’s participant observation with 149 English major undergraduates enrolling in Business English courses in 2016. The results show that participants most often require improvement in note-taking skills, public speaking and need to learn business communication topics. Participants value communicative teaching methodologies, including role plays, oral presentation, theme-based discussion, games and group work. Participants more often rely on electronic media resources, such as videos, internet and mobile applications than the print media resources such as library, books and dictionaries. This study serves as basis for further business English curriculum development and resources provision in the higher education setting. The study also indicates the potential for business English resources development and exploitation in China within the international education environment
Spin-current diode with a ferromagnetic semiconductor
Diode is a key device in electronics: the charge current can flow through the
device under a forward bias, while almost no current flows under a reverse
bias. Here we propose a corresponding device in spintronics: the spin-current
diode, in which the forward spin current is large but the reversed one is
negligible. We show that the lead/ferromagnetic quantum dot/lead system and the
lead/ferromagnetic semiconductor/lead junction can work as spin-current diodes.
The spin-current diode, a low dissipation device, may have important
applications in spintronics, as the conventional charge-current diode does in
electronics.Comment: 5 pages, 3 figure
Theory for electric dipole superconductivity with an application for bilayer excitons
Exciton superfluid is a macroscopic quantum phenomenon in which large
quantities of excitons undergo the Bose-Einstein condensation. Recently,
exciton superfluid has been widely studied in various bilayer systems. However,
experimental measurements only provide indirect evidence for the existence of
exciton superfluid. In this article, by viewing the exciton in a bilayer system
as an electric dipole, we provide a general theory for the electric dipole
superconductivity, and derive the London-type and Ginzburg-Landau-type
equations for the electric dipole superconductors. By using these equations, we
discover the Meissner-type effect and the electric dipole current Josephson
effect. These effects can provide direct evidence for the formation of the
exciton superfluid state in bilayer systems and pave new ways to drive an
electric dipole current.Comment: 10 pages, 5 figures, 1 Supplementary Informatio
The spin-polarized state of graphene: a spin superconductor
We study the spin-polarized Landau-level state of graphene. Due to
the electron-hole attractive interaction, electrons and holes can bound into
pairs. These pairs can then condense into a spin-triplet superfluid ground
state: a spin superconductor state. In this state, a gap opens up in the edge
bands as well as in the bulk bands, thus it is a charge insulator, but it can
carry the spin current without dissipation. These results can well explain the
insulating behavior of the spin-polarized state in the recent
experiments.Comment: 6 pages, 4 figure
Topological Imbert-Fedorov shift in Weyl semimetals
The Goos-H\"anchen (GH) shift and the Imbert-Fedorov (IF) shift are optical
phenomena which describe the longitudinal and transverse lateral shifts at the
reflection interface, respectively. Here, we report the GH and IF shifts in
Weyl semimetals (WSMs) - a promising material harboring low energy Weyl
fermions, a massless fermionic cousin of photons. Our results show that GH
shift in WSMs is valley-independent which is analogous to that discovered in a
2D relativistic material - graphene. However, the IF shift has never been
explored in non-optical systems, and here we show that it is valley-dependent.
Furthermore, we find that the IF shift actually originates from the topological
effect of the system. Experimentally, the topological IF shift can be utilized
to characterize the Weyl semimetals, design valleytronic devices of high
efficiency, and measure the Berry curvature
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