14,241 research outputs found
Mathematical Programs for Belief Propagation and Consensus
This paper develops methods of distributed Bayesian hypothesis tests for
fault detection and diagnosis that are based on belief propagation and
optimization in graphical models. The main challenges in developing distributed
statistical estimation algorithms are i) difficulties in ensuring convergence
and consensus for solutions of distributed inference problems, ii) increasing
computational costs due to lack of scalability, and iii) communication
constraints for networked multi-agent systems. To cope with those challenges,
this manuscript considers i) belief propagation and optimization in graphical
models of complex distributed systems, ii) decomposition methods of
optimization for parallel and iterative computations, and iii) distributed
decision-making protocols.Comment: 25 pages, 2 figures, technical repor
A Note on the Convexity of and its Constrained Optimization Representation
This note provides another proof for the {\em convexity} ({\em strict
convexity}) of over the positive definite cone for
any given positive semidefinite matrix (positive definite matrix
) and the {\em strictly convexity} of over
the positive definite cone for any given . Equivalent optimization
representation with linear matrix inequalities (LMIs) for the functions and are presented. Their
optimization representations with LMI constraints can be particularly useful
for some related synthetic design problems
Roles of Direct Break-up Reaction on Neutrino Scattering off C near Nucleon Threshold Region
Neutrino (antineutrino) scattering off C is one of various important
key reactions for -process in the nucleosysnthesis of light nuclei. Most
of neutrino-nucleus scattering are considered through indirect processes within
the energy range from a few to tens of MeV. Target nuclei are excited by
incident neutrino (antineutrino) through various transitions, and subsequently
decay into other nuclei with emitting particles. But, direct processes are also
feasible, in which incident neutrino (antineutrino) strips directly one nucleon
from target nuclei. Consequently, direct processes may affect abundances of
C and B additionally to indirect processes. We investigate direct
neutrino (antineutrino) quasi-elastic scattering off C around the energy
region liberating one nucleon and discuss implications of direct processes in
the nucleosynthesis. The direct processes might be comparable to the indirect
processes if the final state interaction is taken into account.Comment: 9 pages, 3 figure
Stability Analysis of Discrete-time Lure Systems with Slope-restricted Odd Monotonic Nonlinearities
Many nonlinear dynamical systems can be written as Lure systems, which are
described by a linear time-invariant system interconnected with a diagonal
static sector-bounded nonlinearity. Sufficient conditions are derived for the
global asymptotic stability analysis of discrete-time Lure systems in which the
nonlinearities have restricted slope and/or are odd, which is the usual case in
real applications. A Lure-Postnikov-type Lyapunov function is proposed that is
used to derive sufficient analysis conditions in terms of linear matrix
inequalities (LMIs). The derived stability critera are provably less
conservative than criteria published in the literature, with numerical examples
indicating that conservatism can be reduced by orders of magnitude
General limit on the relation between abundances of D and Li in big bang nucleosynthesis with nucleon injections
The injections of energetic hadrons could have occurred in the early universe
by decays of hypothetical long-lived exotic particles. The injections induce
the showers of nonthermal hadrons via nuclear scattering. Neutrons generated at
these events can react with Be nuclei and reduce Be abundance solving a
problem of the primordial Li abundance. We suggest that thermal neutron
injection is a way to derive a model independent conservative limit on the
relation between abundances of D and Li in a hadronic energy injection
model. We emphasize that an uncertainty in cross sections of inelastic
scattering affects the total number of induced neutrons, which determines final
abundances of D and Li. In addition, the annihilations of antinucleons with
He result in higher D abundance and trigger nonthermal Li production.
It is concluded that a reduction of Li abundance from a value in the
standard big bang nucleosynthesis (BBN) model down to an observational two
upper limit is necessarily accompanied by an undesirable increase of D
abundance up to at least an observational 12 upper limit from
observations of quasi-stellar object absorption line systems. The effects of
antinucleons and secondary particles produced in the hadronic showers always
lead to a severer constraint. The BBN models involving any injections of extra
neutrons are thus unlikely to reproduce a small Li abundance consistent
with observations.Comment: 14 pages, 6 figure
High-lying Gamow-Teller excited states in the deformed nuclei, and , by the smearing of the Fermi surface in Deformed Quasi-particle RPA (DQRPA)
With the advent of high analysis technology in detecting the Gamow-Teller
(GT) excited states beyond one nucleon emission threshold, the quenching of the
GT strength to the Ikeda sum rule seems to be recovered by the high-lying GT
states. Moreover, in some nuclei, the stronger GT peaks than any other peaks
appear explicitly in the high-lying excited states. We address that these
high-lying GT excited states stems from the smearing of the Fermi surface by
the increase of the chemical potential owing to the deformation within a
framework of the deformed quasi-particle random phase approximation (DQRPA).
Detailed mechanism leading to the smearing is discussed, and comparisons to the
available experimental data are shown to explain the strong peaks on the
high-lying GT excited states in a satisfactory manner.Comment: 8 figures. arXiv admin note: substantial text overlap with
arXiv:1205.456
Effects of the density-dependent weak form factors on the neutrino reaction via neutral current for the nucleon in nuclear medium and C
The nucleon form factors in free space are usually thought to be modified
when a nucleon is bound in a nucleus or immersed in a nuclear medium. We
investigate effects of the density-dependent axial and weak-vector form factors
on the electro-neutrino () and anti-electro-neutrino
reactions via neutral current (NC) for a nucleon in nuclear medium or C.
For the density-dependent form factors, we exploit the quark-meson-coupling
(QMC) model, and apply them to the and induced reactions
by NC. About 12% decrease of the total cross section by reaction on the
nucleon is obtained at normal density, , as
well as about 18% reduction of total cross section on C, by
the modification of the weak form factors of the bound nucleon.
However, similarly to the charged current reaction, effects of the nucleon
property change in the reaction reduce significantly the cross
sections about 30% for the nucleon in matter and C cases. Such a large
asymmetry in the cross sections is addressed to originate from
the different helicities of and
The Axial Current in Electromagnetic Interaction
We discussed the possibility that the charged axial currents of matter fields
could be non-conserved in electromagnetic interaction at order. It
means that chiral symmetry is broken explicitly by electromagnetic interaction.
This explicit symmetry breaking of chiral symmetry is shown to lead the mass
differences between the charged and neutral particles of matter fields.Comment: 8 page
A Role of the Axial Vector Mesons on the Photon Production in Heavy Ion Collisions and Their Relevant Decays
A role of the axial vector mesons, such as and , on the emitted
photon spectrum in hot hadronic matter is studied through the channels and . They are shown
to be dominant channels in this spectrum. This study is carried out with an
effective chiral lagrangian which includes vector and axial-vector mesons and
explains well their relevant decays simultaneously.Comment: 12 pages, 2 figure
Corrected constraints on big bang nucleosynthesis in a modified gravity model of
Big bang nucleosynthesis in a modified gravity model of is
investigated. The only free parameter of the model is a power-law index . We
find cosmological solutions in a parameter region of . We calculate abundances of He, D, He, Li, and
Li during big bang nucleosynthesis. We compare the results with the latest
observational data. It is then found that the power-law index is constrained to
be (95 % C.L.) mainly from observations
of deuterium abundance as well as He abundance.Comment: 6 pages, 2 figures, Published by APS at
http://journals.aps.org/prd/abstract/10.1103/PhysRevD.91.10402
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