6,001 research outputs found
Nonparametric Markovian Learning of Triggering Kernels for Mutually Exciting and Mutually Inhibiting Multivariate Hawkes Processes
In this paper, we address the problem of fitting multivariate Hawkes
processes to potentially large-scale data in a setting where series of events
are not only mutually-exciting but can also exhibit inhibitive patterns. We
focus on nonparametric learning and propose a novel algorithm called MEMIP
(Markovian Estimation of Mutually Interacting Processes) that makes use of
polynomial approximation theory and self-concordant analysis in order to learn
both triggering kernels and base intensities of events. Moreover, considering
that N historical observations are available, the algorithm performs
log-likelihood maximization in operations, while the complexity of
non-Markovian methods is in . Numerical experiments on simulated
data, as well as real-world data, show that our method enjoys improved
prediction performance when compared to state-of-the art methods like MMEL and
exponential kernels
Deformation effect on total reaction cross sections for neutron-rich Ne-isotopes
Isotope-dependence of measured reaction cross sections in scattering of
Ne isotopes from C target at 240 MeV/nucleon is analyzed by
the double-folding model with the Melbourne -matrix. The density of
projectile is calculated by the mean-field model with the deformed Wood-Saxon
potential. The deformation is evaluated by the antisymmetrized molecular
dynamics. The deformation of projectile enhances calculated reaction cross
sections to the measured values.Comment: 6 pages, 4 figures, 2 table
Determination of the structure of Ne by full-microscopic framework
We perform the first quantitative analysis of the reaction cross sections of
Ne by C at 240 MeV/nucleon, using the double-folding model
(DFM) with the Melbourne -matrix and the deformed projectile density
calculated by the antisymmetrized molecular dynamics (AMD). To describe the
tail of the last neutron of Ne, we adopt the resonating group method
(RGM) combined with AMD. The theoretical prediction excellently reproduce the
measured cross sections of Ne with no adjustable parameters. The
ground state properties of Ne, i.e., strong deformation and a halo
structure with spin-parity , are clarified.Comment: 4 pages, 4 figures, 2 table
Recent developments in the eikonal description of the breakup of exotic nuclei
The study of exotic nuclear structures, such as halo nuclei, is usually
performed through nuclear reactions. An accurate reaction model coupled to a
realistic description of the projectile is needed to correctly interpret
experimental data. In this contribution, we briefly summarise the assumptions
made within the modelling of reactions involving halo nuclei. We describe
briefly the Continuum-Discretised Coupled Channel method (CDCC) and the
Dynamical Eikonal Approximation (DEA) in particular and present a comparison
between them for the breakup of 15C on Pb at 68AMeV. We show the problem faced
by the models based on the eikonal approximation at low energy and detail a
correction that enables their extension down to lower beam energies. A new
reaction observable is also presented. It consists of the ratio between angular
distributions for two different processes, such as elastic scattering and
breakup. This ratio is completely independent of the reaction mechanism and
hence is more sensitive to the projectile structure than usual reaction
observables, which makes it a very powerful tool to study exotic structures far
from stability.Comment: Contribution to the proceedings of the XXI International School on
Nuclear Physics and Applications & the International Symposium on Exotic
Nuclei, dedicated to the 60th Anniversary of the JINR (Dubna) (Varna,
Bulgaria, 6-12 September 2015), 7 pages, 4 figure
Invariant manifolds and orbit control in the solar sail three-body problem
In this paper we consider issues regarding the control and orbit transfer of solar sails in the circular restricted Earth-Sun system. Fixed points for solar sails in this system have the linear dynamical properties of saddles crossed with centers; thus the fixed points are dynamically unstable and control is required. A natural mechanism of control presents itself: variations in the sail's orientation. We describe an optimal controller to control the sail onto fixed points and periodic orbits about fixed points. We find this controller to be very robust, and define sets of initial data using spherical coordinates to get a sense of the domain of controllability; we also perform a series of tests for control onto periodic orbits. We then present some mission strategies involving transfer form the Earth to fixed points and onto periodic orbits, and controlled heteroclinic transfers between fixed points on opposite sides of the Earth. Finally we present some novel methods to finding periodic orbits in circumstances where traditional methods break down, based on considerations of the Center Manifold theorem
Predict-prevent control method for perturbed excitable systems
We present a control method based on two steps: prediction and prevention.
For prediction we use the anticipated synchronization scheme, considering
unidirectional coupling between excitable systems in a master-slave
configuration. The master is the perturbed system to be controlled, meanwhile
the slave is an auxiliary system which is used to predict the master's
behavior. We demonstrate theoretically and experimentally that an efficient
control may be achieved.Comment: 4 pages, 5 figure
Effects of instillation locations of boulders at bottom of pool-and-weir fishway on migration rate of Zacco platypus
It is important to keep suitable area by boulders in pooland- weir fishway to make the migration rate of fish high. In this study, migrating behaviors of Zacco platypus in pooland- weir fishway were compared with locations of boulders placed on the bottom of pool-and-weir fishway changed. Migration behaviors of Zacco platypus were obtained with the aid of two digital video cameras. It was found that Zacco platypus migrates remarkably uses the space between boulders when boulders were placed on the upper bottom in the pool. It is because the velocity of space between boulders is low compared to other space.The 11th Pacific Symposium on Flow Visualization and Image Processing, 2017, 1-3 December, Kumamoto, Japa
A method for scoring [mi-1] and [mi-1]f in growth tubes
Scoring [mi-1] and [mi-1]f in growth tube
Effect of nitrogen source and pH on the growth of a glutamine requiring strain (glm)
Effect of nitrogen source and pH on the growth of a glutamine requiring strain (glm
The Brieva-Rook Localization of the Microscopic Nucleon-Nucleus Potential
The nonlocality of the microscopic nucleon-nucleus optical potential is
commonly localized by the Brieva-Rook approximation. The validity of the
localization is tested for the proton+Zr scattering at the incident
energies from 65 MeV to 800 MeV. The localization is valid in the wide
incident-energy range.Comment: 20 pages, 8 figure
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