29,002 research outputs found
Efficient detection for multifrequency dynamic phasor analysis
Analysis of harmonic and interharmonic phasors is a promising smart grid measurement and diagnostic tool. This creates the need to deal with multiple phasor components having different amplitudes, including interharmonics with unknown frequency locations. The Compressive Sensing Taylor-Fourier Multifrequency (CSTFM) algorithm provides very accurate results under demanding test conditions, but is computationally demanding. In this paper we present a novel frequency search criterion with significantly improved effectiveness, resulting in a very efficient revised CSTFM algorithm
Stochastic modeling in nanoscale biophysics: Subdiffusion within proteins
Advances in nanotechnology have allowed scientists to study biological
processes on an unprecedented nanoscale molecule-by-molecule basis, opening the
door to addressing many important biological problems. A phenomenon observed in
recent nanoscale single-molecule biophysics experiments is subdiffusion, which
largely departs from the classical Brownian diffusion theory. In this paper, by
incorporating fractional Gaussian noise into the generalized Langevin equation,
we formulate a model to describe subdiffusion. We conduct a detailed analysis
of the model, including (i) a spectral analysis of the stochastic
integro-differential equations introduced in the model and (ii) a microscopic
derivation of the model from a system of interacting particles. In addition to
its analytical tractability and clear physical underpinning, the model is
capable of explaining data collected in fluorescence studies on single protein
molecules. Excellent agreement between the model prediction and the
single-molecule experimental data is seen.Comment: Published in at http://dx.doi.org/10.1214/07-AOAS149 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Comparison of exact and approximate cross-sections in relativistic Coulomb excitation
We present a new method of obtaining time-dependent matrix elements of the
electromagnetic pulse produced by a highly-relativistic projectile. These
matrix elements are used in a coupled-channel calculation to predict the
cross-sections for population of 1- and 2-phonon states of the giant dipole
resonance. Comparisons are made with the predictions of the long-wavelength and
Born approximations.Comment: 26 pages, LaTex2
Dynamic Decomposition of Spatiotemporal Neural Signals
Neural signals are characterized by rich temporal and spatiotemporal dynamics
that reflect the organization of cortical networks. Theoretical research has
shown how neural networks can operate at different dynamic ranges that
correspond to specific types of information processing. Here we present a data
analysis framework that uses a linearized model of these dynamic states in
order to decompose the measured neural signal into a series of components that
capture both rhythmic and non-rhythmic neural activity. The method is based on
stochastic differential equations and Gaussian process regression. Through
computer simulations and analysis of magnetoencephalographic data, we
demonstrate the efficacy of the method in identifying meaningful modulations of
oscillatory signals corrupted by structured temporal and spatiotemporal noise.
These results suggest that the method is particularly suitable for the analysis
and interpretation of complex temporal and spatiotemporal neural signals
Erlangen Programme at Large 3.1: Hypercomplex Representations of the Heisenberg Group and Mechanics
In the spirit of geometric quantisation we consider representations of the
Heisenberg(--Weyl) group induced by hypercomplex characters of its centre. This
allows to gather under the same framework, called p-mechanics, the three
principal cases: quantum mechanics (elliptic character), hyperbolic mechanics
and classical mechanics (parabolic character). In each case we recover the
corresponding dynamic equation as well as rules for addition of probabilities.
Notably, we are able to obtain whole classical mechanics without any kind of
semiclassical limit h->0.
Keywords: Heisenberg group, Kirillov's method of orbits, geometric
quantisation, quantum mechanics, classical mechanics, Planck constant, dual
numbers, double numbers, hypercomplex, jet spaces, hyperbolic mechanics,
interference, Segal--Bargmann representation, Schroedinger representation,
dynamics equation, harmonic and unharmonic oscillator, contextual probabilityComment: AMSLaTeX, 17 pages, 4 EPS pictures in two figures; v2, v3, v4, v5,
v6: numerous small improvement
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