2,084 research outputs found
Answer Set Programming for Non-Stationary Markov Decision Processes
Non-stationary domains, where unforeseen changes happen, present a challenge
for agents to find an optimal policy for a sequential decision making problem.
This work investigates a solution to this problem that combines Markov Decision
Processes (MDP) and Reinforcement Learning (RL) with Answer Set Programming
(ASP) in a method we call ASP(RL). In this method, Answer Set Programming is
used to find the possible trajectories of an MDP, from where Reinforcement
Learning is applied to learn the optimal policy of the problem. Results show
that ASP(RL) is capable of efficiently finding the optimal solution of an MDP
representing non-stationary domains
A methodology for solving single-model, stochastic assembly line balancing problem
Cataloged from PDF version of article.In this paper, a methodology is developed to solve the single-model, stochastic assembly line balancing problem
for the objective of minimizing the total labor cost and the expected incompletion cost arising from tasks not
completed within the prescribed cycle time. The methodology is based on determining an initial DP based solution
and its improvement using a branch-and-bound procedure which uses an approximate solution instead of a lower
bound for fathoming nodes. Detailed experimentation shows the superiority of this method over the most promising
one from the literature. # 1999 Elsevier Science Ltd. All rights reserved
Flux of Primordial Monopoles
We discuss how in supersymmetric models with D and F-flat directions, a
primordial monopole flux of order 10^{-16} - 10^{-18} cm^{-2} sec^{-1} sr^{-1}
can coexist with the observed baryon asymmetry. A modified Affleck-Dine
scenario yields the desired asymmetry if the monopoles are superheavy (~
10^{13}-10^{18} GeV). For lighter monopoles with masses ~ 10^{9}-10^{12} GeV,
the baryon asymmetry can arise via TeV scale leptogenesis.Comment: 17 pages, 4 figures, revtex
Comment on ``Cosmological Gamma Ray Bursts and the Highest Energy Cosmic Rays''
In a letter with the above title, published some time ago in PRL, Waxman made
the interesting suggestion that cosmological gamma ray bursts (GRBs) are the
source of the ultra high energy cosmic rays (UHECR). This has also been
proposed independently by Milgrom and Usov and by Vietri. However, recent
observations of GRBs and their afterglows and in particular recent data from
the Akeno Great Air Shwoer Array (AGASA) on UHECR rule out extragalactic GRBs
as the source of UHECR.Comment: Comment on a letter with the above title published by E. Waxman in
PRL 75, 386 (1995). Submitted for publication in PRL/Comment
Probing Pseudo-Dirac Neutrino through Detection of Neutrino Induced Muons from GRB Neutrinos
The possibility to verify the pseudo-Dirac nature of neutrinos is
investigated here via the detection of ultra high energy neutrinos from distant
cosmological objects like GRBs. The very long baseline and the energy range
from TeV to EeV for such neutrinos invokes the likelihood to
probe very small pseude-Dirac splittings. The expected secondary muons from
such neutrinos that can be detected by a kilometer scale detector such as
ICECUBE is calculated. The pseudo-Dirac nature, if exists, will show a
considerable departure from flavour oscillation scenario in the total yield of
the secondary muons induced by such neutrinos.Comment: 11 pages, 3figure
Can Galactic Observations Be Explained by a Relativistic Gravity Theory?
We consider the possibility of an alternative gravity theory explaining the
dynamics of galactic systems without dark matter. From very general assumptions
about the structure of a relativistic gravity theory we derive a general
expression for the metric to order . This allows us to compare the
predictions of the theory with various experimental data: the Newtonian limit,
light deflection and retardation, rotation of galaxies and gravitational
lensing. Our general conclusion is that the possibility for any gravity theory
to explain the behaviour of galaxies without dark matter is rather improbable.Comment: 12p, REVTeX 3.
On the New Conditions for a Total Neutrino Conversion in a Medium
We show that the arguments forming the basis for the claim that the
conditions for total neutrino conversion derived and studied in detail in [1,2]
``are just the conditions of the parametric resonance of neutrino oscillations
supplemented by the requirement that the parametric enhancement be complete'',
given in [4] have flaws which make the claim physically questionable. We show
also that in the case of the transitions in the Earth of the
Earth-core-crossing solar and atmospheric neutrinos the peaks in the relevant
transitions probabilities , associated with the new conditions, , are of physical relevance - in contrast to what is suggested in
[4]. Actually, the enhancement of in any region of the corresponding
parameter space are essentially determined by these absolute maxima of . We comment on few other aspects of the results derived in [1,2,3] which
have been misunderstood and/or misinterpreted in [4].Comment: 8 pages, late
Impact testing to determine the mechanical properties of articular cartilage in isolation and on bone
The original publication is available at www.springerlink.comNon peer reviewedPostprin
Neutrino, Neutron, and Cosmic Ray Production in the External Shock Model of Gamma Ray Bursts
The hypothesis that ultra-high energy (>~ 10^19 eV) cosmic rays (UHECRs) are
accelerated by gamma-ray burst (GRB) blast waves is assumed to be correct.
Implications of this assumption are then derived for the external shock model
of gamma-ray bursts. The evolving synchrotron radiation spectrum in GRB blast
waves provides target photons for the photomeson production of neutrinos and
neutrons. Decay characteristics and radiative efficiencies of the neutral
particles that escape from the blast wave are calculated. The diffuse
high-energy GRB neutrino background and the distribution of high-energy GRB
neutrino events are calculated for specific parameter sets, and a scaling
relation for the photomeson production efficiency in surroundings with
different densities is derived. GRBs provide an intense flux of high-energy
neutrons, with neutron-production efficiencies exceeding ~ 1% of the total
energy release. The radiative characteristics of the neutron beta-decay
electrons from the GRB "neutron bomb" are solved in a special case. Galaxies
with GRB activity should be surrounded by radiation halos of ~ 100 kpc extent
from the outflowing neutrons, consisting of a nonthermal optical/X-ray
synchrotron component and a high-energy gamma-ray component from
Compton-scattered microwave background radiation. The luminosity of sources of
GRBs and relativistic outflows in L* galaxies such as the Milky Way is at the
level of ~10^40+-1 ergs/s. This is sufficient to account for UHECR generation
by GRBs. We briefly speculate on the possibility that hadronic cosmic rays
originate from the subset of supernovae that collapse to form relativistic
outflows and GRBs. (abridged)Comment: 53 pages, 8 figures, ApJ, in press, 574, July 20, 2002. Substantial
revision, previous Appendix expanded to ApJ, 556, 479; cosmic ray origin
speculations to Heidelberg (astro-ph/001054) and Hamburg ICRC
(astro-ph/0202254) proceeding
Effects of Decays of Tau Neutrinos Near A Supernova
We revisit the constraints implied by SN 1987 A observations on the decay
rate of a multi-MeV decaying into the visible channel , if its lifetime is more than 10 {\it sec.}. We
discuss its implication for the minimal left-right symmetric model with see-saw
mechanism for neutrino masses. We also speculate on the possible formation of a
``giant Capacitor" in intergalactic space due to the decay of "neutronization"
's and spin allignment possibility in the supernova.Comment: 29 Pages, Tex file, UMDHEP 94-4
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