66,827 research outputs found
Field Measurements of Spontaneous Potential (SP) for Smart Well Monitoring and Control. A Field Test in the UK Chalk Aquifer
Imperial Users onl
A deterministic numerical model for the nonlinear Boltzmann equation
We propose a new deterministic numerical scheme, based on the discontinuous
Galerkin method, for solving the Boltzamnn equation for rarefied gases. The new
scheme guarantees the conservation of the mass, momentum and energy. We avoid
any stochastic procedures in the treatment of the collision operator of the
Boltzmamn equation.Comment: Conference: Partial differential equations in kinetic theories:
kinetic description of biological models. Nov 8, 2010 - Nov 12, 2010
Edinburgh (UK) The second version differs from the first only in the MSC
class dat
A non-parametric and scale-independent method for cluster analysis II: the multivariate case
A general method is described for detecting and analysing galaxy systems. The
multivariate geometrical structure of the sample is studied by using an
extension of the method which we introduced in a previous paper. The method is
based on an estimate of the probability density underlying a data sample. The
density is estimated by using an iterative and adaptive kernel estimator. The
used kernels have spherical symmetry, however we describe a method in order to
estimate the locally optimal shape of the kernels. We use the results of the
geometrical structure analysis in order to study the effects that is has on the
cluster parameter estimate. This suggests a possible way to distinguish between
structure and substructure within a sample. The method is tested by using
simulated numerical models and applied to two galaxy samples taken from the
literature. The results obtained for the Coma cluster suggest a core-halo
structure formed by a large number of geometrically independent systems. A
different conclusion is suggested by the results for the Cancer cluster
indicating the presence of at least two independent structures both containing
substructure. The dynamical consequences of the results obtained from the
geometrical analysis will be described in a later paper. Further applications
of the method are suggested and are currently in progress.Comment: To appear in Monthly Notices of R.A.S., 50 pages of text, latex file,
aasms style, figures are available on request from the Autho
Non-linear evolution equations and hyperelliptic covers of elliptic curves
We study the general properties of spectral curves associated to
doubly-periodic solutions of Korteweg-deVries, sine-Gordon, Non-linear
Schr\"odinger and 1D Toda equations, and construct examples of arbitrary genus
Is the cold spot responsible for the CMB North-South asymmetry?
Several intriguing phenomena, unlikely within the standard inflationary
cosmology, were reported in the cosmic microwave background (CMB) data from
WMAP and appear to be uncorrelated. Two of these phenomena, termed CMB
anomalies, are representative of their disparate nature: the North-South
asymmetry in the CMB angular-correlation strength, inconsistent with an
isotropic universe, and the cold spot, producing a significant deviation from
Gaussianity. We find a cause-effect relationship between them, at medium
angular scales (l = 11 - 20): we show that a successive diminution of the cold
spot (absolute-value) temperature implies a monotonic decrease of the
North-South asymmetry power, and moreover we find that the cold spot supplies
60% of such power.Comment: 5 pages, 2 Postscript figure
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