14,304 research outputs found
Earthquake source parameters of the 2009 Mw 7.8 Fiordland (New Zealand) earthquake from L-band InSAR observations
The 2009 MW7.8 Fiordland (New Zealand) earthquake is the largest to have occurred in New Zealand since the 1931 Mw 7.8 Hawke’s Bay earthquake, 1 000 km to the northwest. In this paper two tracks of ALOS PALSAR interferograms (one ascending and one descending) are used to determine fault geometry and slip distribution of this large earthquake. Modeling the event as dislocation in an elastic half-space suggests that the earthquake resulted from slip on a SSW-NNE orientated thrust fault that is associated with the subduction between the Pacific and Australian Plates, with oblique displacement of up to 6.3 m. This finding is consistent with the preliminary studies undertaken by the USGS using seismic data
Magnetohydrodynamic normal mode analysis of plasma with equilibrium pressure anisotropy
In this work, we generalise linear magnetohydrodynamic (MHD) stability theory
to include equilibrium pressure anisotropy in the fluid part of the analysis. A
novel 'single-adiabatic' (SA) fluid closure is presented which is complementary
to the usual 'double-adiabatic' (CGL) model and has the advantage of naturally
reproducing exactly the MHD spectrum in the isotropic limit. As with MHD and
CGL, the SA model neglects the anisotropic perturbed pressure and thus loses
non-local fast-particle stabilisation present in the kinetic approach. Another
interesting aspect of this new approach is that the stabilising terms appear
naturally as separate viscous corrections leaving the isotropic SA closure
unchanged. After verifying the self-consistency of the SA model, we re-derive
the projected linear MHD set of equations required for stability analysis of
tokamaks in the MISHKA code. The cylindrical wave equation is derived
analytically as done previously in the spectral theory of MHD and clear
predictions are made for the modification to fast-magnetosonic and slow ion
sound speeds due to equilibrium anisotropy.Comment: 19 pages. This is an author-created, un-copyedited version of an
article submitted for publication in Plasma Physics and Controlled Fusion.
IOP Publishing Ltd is not responsible for any errors or omissions in this
version of the manuscript or any version derived from i
Impact of energetic particle orbits on long range frequency chirping of BGK modes
Long range frequency chirping of Bernstein-Greene-Kruskal modes, whose
existence is determined by the fast particles, is investigated in cases where
these particles do not move freely and their motion is bounded to restricted
orbits. An equilibrium oscillating potential, which creates different orbit
topologies of energetic particles, is included into the bump-on-tail
instability problem of a plasma wave. With respect to fast particles dynamics,
the extended model captures the range of particles motion (trapped/passing)
with energy and thus represents a more realistic 1D picture of the long range
sweeping events observed for weakly damped modes, e.g. global Alfven
eigenmodes, in tokamaks. The Poisson equation is solved numerically along with
bounce averaging the Vlasov equation in the adiabatic regime. We demonstrate
that the shape and the saturation amplitude of the nonlinear mode structure
depends not only on the amount of deviation from the initial eigenfrequency but
also on the initial energy of the resonant electrons in the equilibrium
potential. Similarly, the results reveal that the resonant electrons following
different equilibrium orbits in the electrostatic potential lead to different
rates of frequency evolution. As compared to the previous model [Breizman B.N.
2010 Nucl. Fusion 50 084014], it is shown that the frequency sweeps with lower
rates. The additional physics included in the model enables a more complete 1D
description of the range of phenomena observed in experiments.Comment: Submitted to Nuclear Fusion 25/01/201
Analytical considerations of flow boiling heat transfer in metal-foam filled tubes
Flow boiling in metal-foam filled tube was analytically investigated based on a modified microstructure model, an original boiling heat transfer model and fin analysis for metal foams. Microstructure model of metal foams was established, by which fiber diameter and surface area density were precisely predicted. The heat transfer model for flow boiling in metal foams was based on annular pattern, in which two phase fluid was composed by vapor region in the center of the tube and liquid region near the wall. However, it was assumed that nucleate boiling performed only in the liquid region. Fin analysis and heat transfer network for metal foams were integrated to obtain the convective heat transfer coefficient at interface. The analytical solution was verified by its good agreement with experimental data. The parametric study on heat transfer coefficient and boiling mechanism was also carried out
Do Anionic Titanium Dioxide Nano-Clusters Reach Bulk Band Gap? A Density Functional Theory Study
The electronic properties of both neutral and anionic (TiO2)n (n = 1-10) clusters are investigated by extensive density functional theory calculations. The predicted electron detachment energies and excitation gaps of anionic clusters agree well with the original experimental anion photoelectron spectra (APES). It is shown that the old way to analyze APES tends to overestimate vertical excitation gaps (VGA) of large anionic clusters, due to the nature of multiple electronic origins for the higher APES bands. Moreover, the VGA of anionic TiO2 clusters are evidently smaller than those of neutral clusters, which may also be the case for other metal oxide clusters with high electron affinity
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