22,475 research outputs found
Monte Carlo simulations of a diffusive shock with multiple scattering angular distributions
We independently develop a simulation code following the previous dynamical
Monte Carlo simulation of the diffusive shock acceleration under the isotropic
scattering law during the scattering process, and the same results are
obtained. Since the same results test the validity of the dynamical Monte Carlo
method for simulating a collisionless shock, we extend the simulation toward
including an anisotropic scattering law for further developing this dynamical
Monte Carlo simulation. Under this extended anisotropic scattering law, a
Gaussian distribution function is used to describe the variation of scattering
angles in the particle's local frame. As a result, we obtain a series of
different shock structures and evolutions in terms of the standard deviation
values of the given Gaussian scattering angular distributions. We find that the
total energy spectral index increases as the standard deviation value of the
scattering angular distribution increases, but the subshock's energy spectral
index decreases as the standard deviation value of the scattering angular
distribution increases.Comment: This article include 10 pages, 8 figures, and accepted by Astronomy
and Astrophysic
Latency Optimal Broadcasting in Noisy Wireless Mesh Networks
In this paper, we adopt a new noisy wireless network model introduced very
recently by Censor-Hillel et al. in [ACM PODC 2017, CHHZ17]. More specifically,
for a given noise parameter any sender has a probability of
of transmitting noise or any receiver of a single transmission in its
neighborhood has a probability of receiving noise.
In this paper, we first propose a new asymptotically latency-optimal
approximation algorithm (under faultless model) that can complete
single-message broadcasting task in time units/rounds in any
WMN of size and diameter . We then show this diameter-linear
broadcasting algorithm remains robust under the noisy wireless network model
and also improves the currently best known result in CHHZ17 by a
factor.
In this paper, we also further extend our robust single-message broadcasting
algorithm to multi-message broadcasting scenario and show it can broadcast
messages in time rounds. This new robust
multi-message broadcasting scheme is not only asymptotically optimal but also
answers affirmatively the problem left open in CHHZ17 on the existence of an
algorithm that is robust to sender and receiver faults and can broadcast
messages in time rounds.Comment: arXiv admin note: text overlap with arXiv:1705.07369 by other author
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