8,161 research outputs found
A functional non-central limit theorem for jump-diffusions with periodic coefficients driven by stable Levy-noise
We prove a functional non-central limit theorem for jump-diffusions with
periodic coefficients driven by strictly stable Levy-processes with stability
index bigger than one. The limit process turns out to be a strictly stable Levy
process with an averaged jump-measure. Unlike in the situation where the
diffusion is driven by Brownian motion, there is no drift related enhancement
of diffusivity.Comment: Accepted to Journal of Theoretical Probabilit
Derivative moments in turbulent shear flows
We propose a generalized perspective on the behavior of high-order derivative
moments in turbulent shear flows by taking account of the roles of small-scale
intermittency and mean shear, in addition to the Reynolds number. Two
asymptotic regimes are discussed with respect to shear effects. By these means,
some existing disagreements on the Reynolds number dependence of derivative
moments can be explained. That odd-order moments of transverse velocity
derivatives tend not vanish as expected from elementary scaling considerations
does not necessarily imply that small-scale anisotropy persists at all Reynolds
numbers.Comment: 11 pages, 7 Postscript figure
An energy-momentum consistent time integration scheme based on a mixed framework for non-linear electro-elastodynamics
The objective of the present work is the introduction of new mixed variational principles for EM time integrators in electromechanics, hence bridging the gap between the previous work presented by the authors in References [11] and [1], opening up the possibility to a variety of new Finite Element implementations
Evidence for magnetic clusters in NiV close to the quantum critical concentration
The d-metal alloy NiV undergoes a quantum phase transition from
a ferromagnetic ground state to a paramagnetic ground state as the vanadium
concentration is increased. We present magnetization, ac-susceptibility and
muon-spin relaxation data at several vanadium concentrations near the critical
concentration at which the onset of ferromagnetic order is
suppressed to zero temperature. Below , the muon data reveal a broad
magnetic field distribution indicative of long-range ordered ferromagnetic
state with spatial disorder. We show evidence of magnetic clusters in the
ferromagnetic phase and close to the phase boundary in this disordered
itinerant system as an important generic ingredient of a disordered quantum
phase transition. In contrast, the temperature dependence of the magnetic
susceptibility above is best described in terms of a magnetic quantum
Griffiths phase with a power-law distribution of fluctuation rates of dynamic
magnetic clusters. At the lowest temperatures, the onset of a short-range
ordered cluster-glass phase is recognized by an increase in the muon
depolarization in transverse fields and maxima in ac-susceptibility.Comment: 6 pages, 5 figures, submitted to Proceedings of SCES 201
Ferromagnetic coupling of mononuclear Fe centers in a self-assembled metal-organic network on Au(111)
The magnetic state and magnetic coupling of individual atoms in nanoscale
structures relies on a delicate balance between different interactions with the
atomic-scale surrounding. Using scanning tunneling microscopy, we resolve the
self-assembled formation of highly ordered bilayer structures of Fe atoms and
organic linker molecules (T4PT) when deposited on a Au(111) surface. The Fe
atoms are encaged in a three-dimensional coordination motif by three T4PT
molecules in the surface plane and an additional T4PT unit on top. Within this
crystal field, the Fe atoms retain a magnetic ground state with easy-axis
anisotropy, as evidenced by X-ray absorption spectroscopy and X-ray magnetic
circular dichroism. The magnetization curves reveal the existence of
ferromagnetic coupling between the Fe centers
Climatology and Modeling of Quasi-monochromatic Atmospheric Gravity Waves Observed over Urbana Illinois
From analyzing nine months of airglow imaging observations of atmospheric gravity waves (AGWs) over Adelaide, Australia (35°S) [Walterscheid et al., 1999] have proposed that many of the quasi-monochromatic waves seen in the images were primarily thermally ducted. Here are presented 15 months of observations, from February 1996 to May 1997, for AGW frequency and propagation direction from a northern latitude site, Urbana Illinois (40°N). As Adelaide, Urbana is geographically distant from large orographic features. Similar to what was found in Adelaide, the AGWs seem to originate from a preferred location during the time period around summer solstice. In conjunction with these airglow data there exists MF radar data to provide winds in the 90 km region and near-simultaneous lidar data which provide a temperature climatology. The temperature data have previously been analyzed by States and Gardner [2000]. The temperature and wind data are used here in a full wave model analysis to determine the characteristics of the wave ducting and wave reflection during the 15 month observation period. This model analysis is applied to this and another existing data set recently described by Nakamura et al. [1999]. It is shown that the existence of a thermal duct around summer solstice can plausibly account for our observations. However, the characteristics of the thermal duct and the ability of waves to be ducted is also greatly dependent on the characteristics of the background wind. A simple model is constructed to simulate the trapping of these waves by such a duct. It is suggested that the waves seen over Urbana originate no more than a few thousand kilometers from the observation site
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