2,561 research outputs found
A new multiparametric topological method for determining the primary cosmic ray mass composition in the knee energy region
The determination of the primary cosmic ray mass composition from the
characteristics of extensive air showers (EAS), obtained at an observation
level in the lower half of the atmosphere, is still an open problem. In this
work we propose a new method of the Multiparametric Topological Analysis and
show its applicability for the determination of the mass composition of the
primary cosmic rays at the PeV energy region.Comment: 8 pages, 4 figures, talk given at Vulcano 2004 Workshop 'Frontier
Objects in Physics and Astrophysics', Vulcano, Italy, 24-29.05.04, to be
published in the Proceedings of the Worksho
Precise determination of muon and electromagnetic shower contents from shower universality property
We consider two new aspects of Extensive Air Shower development universality
allowing to make accurate estimation of muon and electromagnetic (EM) shower
contents in two independent ways. In the first case, to get muon (or EM) signal
in water Cherenkov tanks or in scintillator detectors it is enough to know the
vertical depth of shower maximum and the total signal in the ground detector.
In the second case, the EM signal can be calculated from the primary particle
energy and the zenith angle. In both cases the parametrizations of muon and EM
signals are almost independent on primary particle nature, energy and zenith
angle. Implications of the considered properties for mass composition and
hadronic interaction studies are briefly discussed. The present study is
performed on 28000 of proton, oxygen and iron showers, generated with CORSIKA
6.735 for spectrum in the energy range log(E/eV)=18.5-20.0 and
uniformly distributed in cos^2(theta) in zenith angle interval theta=0-65
degrees for QGSJET II/Fluka interaction models.Comment: Submitted to Phys. Rev.
Comparison between methods for the determination of the primary cosmic ray mass composition from the longitudinal profile of atmospheric cascades
The determination of the primary cosmic ray mass composition from the
longitudinal development of atmospheric cascades is still a debated issue. In
this work we discuss several data analysis methods and show that if the entire
information contained in the longitudinal profile is exploited, reliable
results may be obtained. Among the proposed methods FCC ('Fit of the Cascade
Curve'), MTA ('Multiparametric Topological Analysis') and NNA ('Neural Net
Analysis') with conjugate gradient optimization algorithm give the best
accuracy.Comment: 22 pages, 11 figures, accepted by Astroparticle Physics, minor
misprints and an extra figure remove
An accident waiting to happen.
This piece was exhibited at the Kinetic Art Fair 2011 in London
Fokker-Planck type equations with Sobolev diffusion coefficients and BV drift coefficients
In this paper we give an affirmative answer to an open question mentioned in
[Le Bris and Lions, Comm. Partial Differential Equations 33 (2008),
1272--1317], that is, we prove the well-posedness of the Fokker-Planck type
equations with Sobolev diffusion coefficients and BV drift coefficients.Comment: 11 pages. The proof has been modifie
2-D constrained Navier-Stokes equation and intermediate asymptotics
We introduce a modified version of the two-dimensional Navier-Stokes
equation, preserving energy and momentum of inertia, which is motivated by the
occurrence of different dissipation time scales and related to the gradient
flow structure of the 2-D Navier-Stokes equation. The hope is to understand
intermediate asymptotics. The analysis we present here is purely formal. A
rigorous study of this equation will be done in a forthcoming paper
New porous medium Poisson-Nernst-Planck equations for strongly oscillating electric potentials
We consider the Poisson-Nernst-Planck system which is well-accepted for
describing dilute electrolytes as well as transport of charged species in
homogeneous environments. Here, we study these equations in porous media whose
electric permittivities show a contrast compared to the electric permittivity
of the electrolyte phase. Our main result is the derivation of convenient
low-dimensional equations, that is, of effective macroscopic porous media
Poisson-Nernst-Planck equations, which reliably describe ionic transport. The
contrast in the electric permittivities between liquid and solid phase and the
heterogeneity of the porous medium induce strongly oscillating electric
potentials (fields). In order to account for this special physical scenario, we
introduce a modified asymptotic multiple-scale expansion which takes advantage
of the nonlinearly coupled structure of the ionic transport equations. This
allows for a systematic upscaling resulting in a new effective porous medium
formulation which shows a new transport term on the macroscale. Solvability of
all arising equations is rigorously verified. This emergence of a new transport
term indicates promising physical insights into the influence of the microscale
material properties on the macroscale. Hence, systematic upscaling strategies
provide a source and a prospective tool to capitalize intrinsic scale effects
for scientific, engineering, and industrial applications
A new method for the UHECR mass composition studies
The detemination of the primary cosmic ray mass composition from the
longitudinal development of atmospheric cascades is still an open problem. In
this work we propose a new method of the multiparametric topological analysis
and show that if both X - the depth of shower maximum and N -
the number of charged particles in the shower maximum are used, reliable
results can be obtained.Comment: 6 pages, 4 figures, talk given at CRIS2004 Cosmic Ray International
Seminar 'GZK and Surroundings', 31.05-4.06.04, Catania, Italy, to be
published in Nucl.Phys.B (Proc.Suppl.
Calculus and heat flow in metric measure spaces and applications to spaces with Ricci bounds from below
This paper is devoted to a deeper understanding of the heat flow and to the
refinement of calculus tools on metric measure spaces (X,d,m). Our main results
are:
- A general study of the relations between the Hopf-Lax semigroup and
Hamilton-Jacobi equation in metric spaces (X,d).
- The equivalence of the heat flow in L^2(X,m) generated by a suitable
Dirichlet energy and the Wasserstein gradient flow of the relative entropy
functional in the space of probability measures P(X).
- The proof of density in energy of Lipschitz functions in the Sobolev space
W^{1,2}(X,d,m).
- A fine and very general analysis of the differentiability properties of a
large class of Kantorovich potentials, in connection with the optimal transport
problem.
Our results apply in particular to spaces satisfying Ricci curvature bounds
in the sense of Lott & Villani [30] and Sturm [39,40], and require neither the
doubling property nor the validity of the local Poincar\'e inequality.Comment: Minor typos corrected and many small improvements added. Lemma 2.4,
Lemma 2.10, Prop. 5.7, Rem. 5.8, Thm. 6.3 added. Rem. 4.7, Prop. 4.8, Prop.
4.15 and Thm 4.16 augmented/reenforced. Proof of Thm. 4.16 and Lemma 9.6
simplified. Thm. 8.6 corrected. A simpler axiomatization of weak gradients,
still equivalent to all other ones, has been propose
- âŠ