35,223 research outputs found
Note on Inversion Formula to Determine Binary Elements by Astrometry
Simplified solutions to determine binary elements by astrometry were obtained
in terms of elementary functions (Asada et al. 2004), and therefore require
neither iterative nor numerical methods. In the framework of the simplified
solution, this paper discusses the remaining two parameters of the time of
periastron passage and the longitude of ascending node in order to complete the
solution. We thus clarify a difference between the simplified solution and
other analytical methods.Comment: 12 pages, 4 figures, 2 tables; accepted for publication in PAS
Interpretations of SUSY Searches in ATLAS with Simplified Models
We present the status of interpretations of Supersymmetry (SUSY) searches in
ATLAS at the Large Hadron Collider (LHC) using simplified models. Such models
allow a systematic scan through the phase space in the sparticle mass plane,
and in the corresponding final state kinematics. Models at various levels of
simplification have been studied in ATLAS. The results can be extrapolated to
more general new physics models which lead to the same event topology with
similar mass hierarchies. Searches in the no-lepton channel with 1.04 fb^-1 of
data from 2011 and the same-sign dilepton channel with 35 pb^-1 of data from
2010 are presented. No excess above the Standard Model expectation is observed,
and the results are interpreted using the simplified models.Comment: 9 pages, 7 figures, 3 tables, for the proceedings of the DPF-2011
conference, Providence, RI, August 9-13, 201
Vectorization and Parallelization of the Adaptive Mesh Refinement N-body Code
In this paper, we describe our vectorized and parallelized adaptive mesh
refinement (AMR) N-body code with shared time steps, and report its performance
on a Fujitsu VPP5000 vector-parallel supercomputer. Our AMR N-body code puts
hierarchical meshes recursively where higher resolution is required and the
time step of all particles are the same. The parts which are the most difficult
to vectorize are loops that access the mesh data and particle data. We
vectorized such parts by changing the loop structure, so that the innermost
loop steps through the cells instead of the particles in each cell, in other
words, by changing the loop order from the depth-first order to the
breadth-first order. Mass assignment is also vectorizable using this loop order
exchange and splitting the loop into loops, if the cloud-in-cell
scheme is adopted. Here, is the number of dimension. These
vectorization schemes which eliminate the unvectorized loops are applicable to
parallelization of loops for shared-memory multiprocessors. We also
parallelized our code for distributed memory machines. The important part of
parallelization is data decomposition. We sorted the hierarchical mesh data by
the Morton order, or the recursive N-shaped order, level by level and split and
allocated the mesh data to the processors. Particles are allocated to the
processor to which the finest refined cells including the particles are also
assigned. Our timing analysis using the -dominated cold dark matter
simulations shows that our parallel code speeds up almost ideally up to 32
processors, the largest number of processors in our test.Comment: 21pages, 16 figures, to be published in PASJ (Vol. 57, No. 5, Oct.
2005
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