44,277 research outputs found
Radial deformation of the earth by oceanic tidal loading
A high-degree spherical harmonic series is used to compute the radial deformation of the Earth by oceanic tidal loading. By exploiting fast numerical transforms, this approach is found to be much more efficient, but no less accurate, than the traditional Green's function approach. The method is used to derive an atlas of load tide maps for 10 constitutents of the NSWC ocean tide model
Complexity in forecasting and predictive models
Te challenge of this special issue has been to know the
state of the problem related to forecasting modeling and
the creation of a model to forecast the future behavior
that supports decision making by supporting real-world applications.
Tis issue has been highlighted by the quality of its
research work on the critical importance of advanced analytical methods, such as neural networks, sof computing,
evolutionary algorithms, chaotic models, cellular automata,
agent-based models, and fnite mixture minimum squares
(FIMIX-PLS).info:eu-repo/semantics/publishedVersio
Influence of quenched dilution on the quasi-long-range ordered phase of the 2d XY model
The influence of non magnetic impurities in the 2d XY model is investigated
through Monte Carlo (MC) simulations. The general picture of the transition is
fully understood from the Harris criterion which predicts that the universality
class is unchanged, and the Berezinskii-Kosterlitz-Thouless description of the
topological transition remains valid. We nevertheless address here the question
about the influence of dilution on the quasi-long-range order at low
temperatures. In particular, we study the asymptotic of the pair correlation
function and report the MC estimates for the critical exponent at
different dilutions. In the weak dilution region, our MC calculations are
further supported by simple spin-wave-like calculations.Comment: 8 pages, 7 eps figure
Breathers in FPU systems, near and far from the phonon band
There exists a recent mathematical proof on the existence of small amplitude
breathers in FPU systems near the phonon band, which includes a prediction of
their amplitude and width. In this work we obtain numerically these breathers,
and calculate the range of validity of the predictions, which extends
relatively far from the phonon band. There exist also large amplitude breathers
with the same frequency, with the consequence that there is an energy gap for
breather creation in these systems.Comment: 3 pages, 2 figures, proceeding of the conference on Localization and
to and Energy Transfer in Nonlinear Systems, June 17-21, 2002, San Lorenzo de
El Escorial, Madrid, Spain. To be published by World Scientifi
The Stellar Mass Fundamental Plane: The virial relation and a very thin plane for slow-rotators
Early-type galaxies -- slow and fast rotating ellipticals (E-SRs and E-FRs)
and S0s/lenticulars -- define a Fundamental Plane (FP) in the space of
half-light radius , enclosed surface brightness and velocity
dispersion . Since and are distance-independent
measurements, the thickness of the FP is often expressed in terms of the
accuracy with which and can be used to estimate sizes .
We show that: 1) The thickness of the FP depends strongly on morphology. If the
sample only includes E-SRs, then the observed scatter in is ,
of which only is intrinsic. Removing galaxies with
further reduces the observed scatter to ( intrinsic). The observed scatter increases to the usually
quoted in the literature if E-FRs and S0s are added. If the FP is defined using
the eigenvectors of the covariance matrix of the observables, then the E-SRs
again define an exceptionally thin FP, with intrinsic scatter of only
orthogonal to the plane. 2) The structure within the FP is most easily
understood as arising from the fact that and are nearly
independent, whereas the and correlations are nearly
equal and opposite. 3) If the coefficients of the FP differ from those
associated with the virial theorem the plane is said to be `tilted'. If we
multiply by the global stellar mass-to-light ratio and we account
for non-homology across the population by using S\'ersic photometry, then the
resulting stellar mass FP is less tilted. Accounting self-consistently for
gradients will change the tilt. The tilt we currently see suggests that
the efficiency of turning baryons into stars increases and/or the dark matter
fraction decreases as stellar surface brightness increases.Comment: 13 pages, 9 figures, 3 tables, accepted for publication in MNRA
Continuous Time Random Walks in periodic systems: fluid limit and fractional differential equations on the circle
In this article, the continuous time random walk on the circle is studied. We
derive the corresponding generalized master equation and discuss the effects of
topology, especially important when Levy flights are allowed. Then, we work out
the fluid limit equation, formulated in terms of the periodic version of the
fractional Riemann-Liouville operators, for which we provide explicit
expressions. Finally, we compute the propagator in some simple cases. The
analysis presented herein should be relevant when investigating anomalous
transport phenomena in systems with periodic dimensions.Comment: 14 pages, 1 figure. References added. Published versio
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