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Modified Green's Functions for Shallow Water Acoustic Wave Propagation
This article presents an assessment of alternative forms of the Green’s function for boundary element simulations of acoustic wave propagation in shallow water. It is assumed that the problem is two-dimensional, the source of acoustic disturbance is time-harmonic, the velocity of sound is constant and the medium in the absence of perturbations is quiescent.
Efficient implementations of the boundary element method for underwater acoustics should employ Green's functions which directly satisfy the boundary conditions on the free surface and the horizontal parts of the bottom boundary. In the present work, these Green's functions are constructed by using different techniques, namely the method of images, eigenfunction expansions and the Ewald’s method
Compositional uniformity, domain patterning and the mechanism underlying nano-chessboard arrays
We propose that systems exhibiting compositional patterning at the nanoscale,
so far assumed to be due to some kind of ordered phase segregation, can be
understood instead in terms of coherent, single phase ordering of minority
motifs, caused by some constrained drive for uniformity. The essential features
of this type of arrangements can be reproduced using a superspace construction
typical of uniformity-driven orderings, which only requires the knowledge of
the modulation vectors observed in the diffraction patterns. The idea is
discussed in terms of a simple two dimensional lattice-gas model that simulates
a binary system in which the dilution of the minority component is favored.
This simple model already exhibits a hierarchy of arrangements similar to the
experimentally observed nano-chessboard and nano-diamond patterns, which are
described as occupational modulated structures with two independent modulation
wave vectors and simple step-like occupation modulation functions.Comment: Preprint. 11 pages, 11 figure
Microscopic phenomena and a modern approach to turbulence
The use of an arc driven shock tube as a technique in the study of turbulence and evidence to support a kinetic theory of turbulence are described. Topics covered include: (1) reaction rate distortion in turbulent flow; (2) turbulent bursts in a shock tube; (3) driver gas flow with fluctuations; (4) improving the Mach number capabilities of arc driver shock tubes; and (5) resonant absorption in an argon plasma at thermal equilibrium
Decomposition driven interface evolution for layers of binary mixtures: I. Model derivation and stratified base states
A dynamical model is proposed to describe the coupled decomposition and
profile evolution of a free surface film of a binary mixture. An example is a
thin film of a polymer blend on a solid substrate undergoing simultaneous phase
separation and dewetting. The model is based on model-H describing the coupled
transport of the mass of one component (convective Cahn-Hilliard equation) and
momentum (Navier-Stokes-Korteweg equations) supplemented by appropriate
boundary conditions at the solid substrate and the free surface.
General transport equations are derived using phenomenological
non-equilibrium thermodynamics for a general non-isothermal setting taking into
account Soret and Dufour effects and interfacial viscosity for the internal
diffuse interface between the two components. Focusing on an isothermal setting
the resulting model is compared to literature results and its base states
corresponding to homogeneous or vertically stratified flat layers are analysed.Comment: Submitted to Physics of Fluid
Turbulence Time Series Data Hole Filling using Karhunen-Loeve and ARIMA methods
Measurements of optical turbulence time series data using unattended
instruments over long time intervals inevitably lead to data drop-outs or
degraded signals. We present a comparison of methods using both Principal
Component Analysis, which is also known as the Karhunen--Loeve decomposition,
and ARIMA that seek to correct for these event-induced and mechanically-induced
signal drop-outs and degradations. We report on the quality of the correction
by examining the Intrinsic Mode Functions generated by Empirical Mode
Decomposition. The data studied are optical turbulence parameter time series
from a commercial long path length optical anemometer/scintillometer, measured
over several hundred metres in outdoor environments.Comment: 8 pages, 9 figures, submitted to ICOLAD 2007, City University,
London, U
Contribution of exclusive channels to the leading order HVP of the muon
We evaluate the contributions of
exclusive channels to the dispersion integral of the leading order HVP of the
muon anomalous magnetic moment. These channels are included in some way in
previous evaluations of the and
contributions to , where the vector resonances (decaying
into ) are assumed to be on-shell. Since the separation of
resonance and background contributions in a given observable is, in general, a
model-dependent procedure, here we use pseudoscalar mesons and the photon as
the and states of the -matrix, such that the cross section contains the
interferences among different contributing to the amplitudes. We find , where
uncertainties stem mainly from vector meson dominance model parameters.
Improved experimental studies of these exclusive channels in the whole range
below 2 GeV would reduce model-dependency
Large Scale Instrumental Test Embankment on Uranium Tailings
The remediation of an inactive uranium mill tailings pile at the town of Andujar (Spain) has provided an opportunity to investigate the settlement characteristics of hydraulically-deposited uranium mill tailings. A test embankment was constructed on top of the existing tailings deposit and total stresses, settlements and pore pressures were measured. Settlements and pore pressure data were compared with the results obtained using an elastoplastic numerical model which allows the simulation of two dimensional consolidation processes. Backcalculated consolidation parameters were derived to provide agreement between the calculated and measured settlements and pore pressures. These parameters could then be used to predict the post-construction settlement of the remediated pile
Highly variable Vitis microsatellite loci for the identification of Pinot Noir clones
Nineteen new microsatellite loci of Vitis were elaborated by following the procedure of tagging an SSRenriched library. Primers for these VRG markers were used for genotyping grapevines. Only the markers VRG 1, VRG 2, VRG 4, VRG 7, VRG 9, VRG 10, VRG 15 and VRG 16 show heterozygous alleles and Mendelian segregation. Other VRG loci such as VRG 5, VRG 6, VRG 11, VRG 12 VRG 13 and VRG 17 produce a multiallelic profile and some of them show distorted segregation. Variability of the VRG loci is rather high as compared to other grapevine SSR markers. Stable VRG markers such as VRG 16 can be useful for the identification of cultivars. Highly variable VRG microsatellites could be successfully applied to trace polymorphism within the variety Pinot Noir. Clones of Pinot Noir could be differentiated using these markers. By applying the PhyQuest program, a dendrogramm showing the genetic divergence within Pinot Noir clones was constructed.
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