21,026 research outputs found
Large-time Behavior of Solutions to the Inflow Problem of Full Compressible Navier-Stokes Equations
Large-time behavior of solutions to the inflow problem of full compressible
Navier-Stokes equations is investigated on the half line .
The wave structure which contains four waves: the transonic(or degenerate)
boundary layer solution, 1-rarefaction wave, viscous 2-contact wave and
3-rarefaction wave to the inflow problem is described and the asymptotic
stability of the superposition of the above four wave patterns to the inflow
problem of full compressible Navier-Stokes equations is proven under some
smallness conditions. The proof is given by the elementary energy analysis
based on the underlying wave structure. The main points in the proof are the
degeneracies of the transonic boundary layer solution and the wave interactions
in the superposition wave.Comment: 27 page
Microscopic interface phonon modes in structures of GaAs quantum dots embedded in AlAs shells
By means of a microscopic valence force field model, a series of novel
microscopic interface phonon modes are identified in shell quantum dots(SQDs)
composed of a GaAs quantum dot of nanoscale embedded in an AlAs shell of a few
atomic layers in thickness. In SQDs with such thin shells, the basic principle
of the continuum dielectric model and the macroscopic dielectric function are
not valid any more. The frequencies of these microscopic interface modes lie
inside the gap between the bulk GaAs band and the bulk AlAs band, contrary to
the macroscopic interface phonon modes. The average vibrational energies and
amplitudes of each atomic shell show peaks at the interface between GaAs and
AlAs. These peaks decay fast as their penetrating depths from the interface
increase.Comment: 13 pages, 4 figure
Relationship of transport coefficients with statistical quantities of charged particles
In the previous studies, from the Fokker-Planck equation the general spatial
transport equation, which contains an infinite number of spatial derivative
terms with ,
was derived. Due to the complexity of the general equation, some simplified
equations with finite spatial derivative terms have been used in astrophysical
researches, e.g., the diffusion equation, the hyperdiffusion one, subdiffusion
transport one, etc. In this paper, the simplified equations with the highest
order spatial derivative terms up to the first-, second-, third-, fourth-, and
fifth-order are listed, and their transport coefficient formulas are derived,
respectively. We find that most of the transport coefficients are determined by
the corresponding statistical quantities. In addition, we find that the
well-known statistical quantities, skewness and kurtosis
, are determined by some transport coefficients. The results can
help one to use different transport coefficients determined by the statistical
quantities, including many that are relatively new found in this paper, to
study charged particle parallel transport processes
The effect of solar wind on the charged particles' diffusion coefficients
The transport of energetic charged particles through magnetized plasmas is
ubiquitous in interplanetary space and astrophysics, and the important physical
quantities are the along-field and cross-field spatial diffusion coefficients
of energetic charged particles. In this paper, the influence of solar wind on
particle transport is investigated. Using the focusing equation, we obtain
along- and cross-field diffusion coefficient accounting for the solar wind
effect. For different conditions, the relative importance of solar wind effect
to diffusion are investigated. It is shown that when energetic charged
particles are close to the sun, for along-field diffusion the solar wind effect
needs to be taken into account. These results are important for studying
energetic charged particle transport processes in the vicinity of the sun
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