9,097 research outputs found
Incremental and Transitive Discrete Rotations
A discrete rotation algorithm can be apprehended as a parametric application
from \ZZ[i] to \ZZ[i], whose resulting permutation ``looks
like'' the map induced by an Euclidean rotation. For this kind of algorithm, to
be incremental means to compute successively all the intermediate rotate d
copies of an image for angles in-between 0 and a destination angle. The di
scretized rotation consists in the composition of an Euclidean rotation with a
discretization; the aim of this article is to describe an algorithm whic h
computes incrementally a discretized rotation. The suggested method uses o nly
integer arithmetic and does not compute any sine nor any cosine. More pr
ecisely, its design relies on the analysis of the discretized rotation as a
step function: the precise description of the discontinuities turns to be th e
key ingredient that will make the resulting procedure optimally fast and e
xact. A complete description of the incremental rotation process is provided,
also this result may be useful in the specification of a consistent set of
defin itions for discrete geometry
Stability of Coalescence Hidden variable Fractal Interpolation Surfaces
In the present paper, the stability of Coalescence Hidden variable Fractal
Interpolation Surfaces(CHFIS) is established. The estimates on error in
approximation of the data generating function by CHFIS are found when there is
a perturbation in independent, dependent and hidden variables. It is proved
that any small perturbation in any of the variables of generalized
interpolation data results in only small perturbation of CHFIS. Our results are
likely to be useful in investigations of texture of surfaces arising from the
simulation of surfaces of rocks, sea surfaces, clouds and similar natural
objects wherein the generating function depends on more than one variable
Inverse Anticipating Synchronization
We report a new type of chaos synchronization:inverse anticipating
synchronization, where a time delay chaotic system can drive another system in
such a way that the driven system anticipates the driver by synchronizing with
its inverse future state. We extend the concept of inverse anticipating chaos
synchronization to cascaded systems. We propose means for the experimental
observation of inverse anticipating chaos synchronization in external cavity
lasers.Comment: LaTex 6 pages, resubmitted to PR
128Xe and 130Xe: Testing He-shell burning in AGB stars
The s-process branching at 128I has been investigated on the basis of new,
precise experimental (n,g) cross sections for the s-only isotopes 128Xe and
130Xe. This branching is unique, since it is essentially determined by the
temperature- and density-sensitive stellar decay rates of 128I and only
marginally affected by the specific stellar neutron flux. For this reason it
represents an important test for He-shell burning in AGB stars. The description
of the branching by means of the complex stellar scenario reveals a significant
sensitivity to the time scales for convection during He shell flashes, thus
providing constraints for this phenomenon. The s-process ratio 128Xe/130Xe
deduced from stellar models allows for a (9+-3)% p-process contribution to
solar 128Xe, in agreement with the Xe-S component found in meteoritic presolar
SiC grains.Comment: 24 pages, 9 figures, accepted for publication in Astophysical Journa
Revisiting Digital Straight Segment Recognition
This paper presents new results about digital straight segments, their
recognition and related properties. They come from the study of the
arithmetically based recognition algorithm proposed by I. Debled-Rennesson and
J.-P. Reveill\`es in 1995 [Debled95]. We indeed exhibit the relations
describing the possible changes in the parameters of the digital straight
segment under investigation. This description is achieved by considering new
parameters on digital segments: instead of their arithmetic description, we
examine the parameters related to their combinatoric description. As a result
we have a better understanding of their evolution during recognition and
analytical formulas to compute them. We also show how this evolution can be
projected onto the Stern-Brocot tree. These new relations have interesting
consequences on the geometry of digital curves. We show how they can for
instance be used to bound the slope difference between consecutive maximal
segments
The First Year IceCube-DeepCore Results
The IceCube Neutrino Observatory includes a tightly spaced inner array in the
deepest ice, called DeepCore, which gives access to low-energy neutrinos with a
sizable surrounding cosmic ray muon veto. Designed to be sensitive to neutrinos
at energies as low as 10 GeV, DeepCore will be used to study diverse physics
topics with neutrino signatures, such as dark matter annihilations and
atmospheric neutrino oscillations. The first year of DeepCore physics
data-taking has been completed, and the first observation of atmospheric
neutrino-induced cascades with IceCube and DeepCore are presented.Comment: 4 pages, 3 figures, TAUP 2011 (Journal of Physics: Conference Series
(JCPS)
Decomposing Service Definition in Predicate/Transition-Nets for Designing Distributed Systems
In this paper, we propose a new algorithm for the derivation of a protocol specification in Pr/T-nets, which is the specification of communicating N entities (N can be given), from a given service specification in Pr/T-nets and an allocation of the places of the service specification to the N entities. Our algorithm decomposes each transition of the service specification into a set of communicating Pr/T-subnets running on the N entities. Moreover, for the efficient control of conflict of shared resources, we present a timestamp-based mutual exclusion algorithm and incorporate it into the derivation algorithm
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