6,605 research outputs found
Analysis of a diffusive effective mass model for nanowires
We propose in this paper to derive and analyze a self-consistent model
describing the diffusive transport in a nanowire. From a physical point of
view, it describes the electron transport in an ultra-scaled confined
structure, taking in account the interactions of charged particles with
phonons. The transport direction is assumed to be large compared to the wire
section and is described by a drift-diffusion equation including effective
quantities computed from a Bloch problem in the crystal lattice. The
electrostatic potential solves a Poisson equation where the particle density
couples on each energy band a two dimensional confinement density with the
monodimensional transport density given by the Boltzmann statistics. On the one
hand, we study the derivation of this Nanowire Drift-Diffusion Poisson model
from a kinetic level description. On the other hand, we present an existence
result for this model in a bounded domain
Two-loop scalar self-energies and pole masses in a general renormalizable theory with massless gauge bosons
I present the two-loop self-energy functions for scalar bosons in a general
renormalizable theory, within the approximation that vector bosons are treated
as massless or equivalently that gauge symmetries are unbroken. This enables
the computation of the two-loop physical pole masses of scalar particles in
that approximation. The calculations are done simultaneously in the
mass-independent \bar{MS}, \bar{DR}, and \bar{DR}' renormalization schemes, and
with arbitrary covariant gauge fixing. As an example, I present the two-loop
SUSYQCD corrections to squark masses, which can increase the known one-loop
results by of order one percent. More generally, it is now straightforward to
implement all two-loop sfermion pole mass computations in supersymmetry using
the results given here, neglecting only the electroweak vector boson masses
compared to the superpartner masses in the two-loop parts.Comment: 16 pages, 4 figures. v2: typo in eq. (5.30) fixe
An effective mass theorem for the bidimensional electron gas in a strong magnetic field
We study the limiting behavior of a singularly perturbed
Schr\"odinger-Poisson system describing a 3-dimensional electron gas strongly
confined in the vicinity of a plane and subject to a strong uniform
magnetic field in the plane of the gas. The coupled effects of the confinement
and of the magnetic field induce fast oscillations in time that need to be
averaged out. We obtain at the limit a system of 2-dimensional Schr\"odinger
equations in the plane , coupled through an effective selfconsistent
electrical potential. In the direction perpendicular to the magnetic field, the
electron mass is modified by the field, as the result of an averaging of the
cyclotron motion. The main tools of the analysis are the adaptation of the
second order long-time averaging theory of ODEs to our PDEs context, and the
use of a Sobolev scale adapted to the confinement operator
Stability and finite-time stability analysis of discrete-time nonlinear networked control systems
In this paper we present an approach to model networked control systems with a discrete-time nonlinear plant, operating in the presence of arbitrary but finite data dropout of state observations. Sufficient conditions for stability of the global system and finite-time stability over transmission intervals are provided
Finite-time stability of discrete-time nonlinear systems: analysis and design
Finite-time stability of nonlinear discrete-time systems is studied. Some new analysis results are developed and applied to controller design
Model-based networked control for finite-time stability of nonlinear systems: the stochastic case
In this paper we analyze model-based networked control systems for a discrete-time nonlinear plant model, operating in the presence of stochastic dropout of state observations. The dropout is modeled as a Markov chain, and sufficient conditions for finite-time stochastic stability are provided using the stochastic version of Lyapunov second method. In a companion paper we model the dropout as a deterministic sequence
Anomalous photon thermal Hall effect
We predict an anomalous thermal Hall effect (ATHE) mediated by photons in
networks of Weyl semi-metals. Contrary to the photon thermal Hall effect in
magneto-optical systems which requires the application of an external magnetic
field the ATHE in a Weyl semi-metals network is an intrinsic property of these
systems. Since the Weyl semi-metals can exhibit a strong nonreciprocal response
in the infrared over a broad spectral range the magnitude of thermal Hall flux
in these systems can be relatively large compared to the primary flux. This
ATHE paves the way for a directional control of heat flux by localy tuning the
magnitude of temperature field without changing the direction of temperature
gradient
Output Stabilizability
In this report, we provide algebraic tests to determine whether a linear Single-Input-Single-Output (SISO) system, is stabilizable with a constant output feedback
Potentialités androgénétiques du palmier dattier Phoenix dactylifera L. et culture in vitro d'anthères
Genetic potentialities if five male date palm genotypes, and in vitro culture of anthers. The experimental results derived from the study of five date palm (Phoenix dactylifera L.) genotypes indicate that the ability of microspores to divide varies with genotype and culture medium. The highest frequency of microspore division is obtained with the induction medium [Murashige and Skoog (MS 1962) mineral elements, 2,4-dichlorophenoxyacetique (2,4-D), 2-isopentenylaminopurine (2-IP)] containing activated charcoal. The pollinator T106 was considered as the most efficient genotype in our experimentatio
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