648 research outputs found
A SVD accelerated kernel-independent fast multipole method and its application to BEM
The kernel-independent fast multipole method (KIFMM) proposed in [1] is of
almost linear complexity. In the original KIFMM the time-consuming M2L
translations are accelerated by FFT. However, when more equivalent points are
used to achieve higher accuracy, the efficiency of the FFT approach tends to be
lower because more auxiliary volume grid points have to be added. In this
paper, all the translations of the KIFMM are accelerated by using the singular
value decomposition (SVD) based on the low-rank property of the translating
matrices. The acceleration of M2L is realized by first transforming the
associated translating matrices into more compact form, and then using low-rank
approximations. By using the transform matrices for M2L, the orders of the
translating matrices in upward and downward passes are also reduced. The
improved KIFMM is then applied to accelerate BEM. The performance of the
proposed algorithms are demonstrated by three examples. Numerical results show
that, compared with the original KIFMM, the present method can reduce about 40%
of the iterating time and 25% of the memory requirement.Comment: 19 pages, 4 figure
A -vertex Kernel for -packing
The -packing problem asks for whether a graph contains
vertex-disjoint paths each of length two. We continue the study of its
kernelization algorithms, and develop a -vertex kernel
Ways to cultivate students’ innovative ability in computer teaching in adult education
This paper will focus on the feasibility of cultivating students’ innovative ability in adult education computer teaching.
Combining theory with practice, this paper aims to fi nd out eff ective methods and strategies to stimulate and cultivate students’ innovative
ability in adult computer teaching through exploration and research, and provide operable and highly instructive suggestions for adult
computer teaching. Finally, improve students’ computer application ability and innovation quality, and help them better ada pt to social
development
Top quark forward-backward asymmetry at the Tevatron: a comparative study in different new physics models
The top quark forward-backward asymmetry A_{FB}^t measured at the Tevatron is
above the Standard Model prediction by more than 2-sigma deviation, which might
be a harbinger for new physics. In this work we examine the contribution to
A_{FB}^t in two different new physics models: one is the minimal supersymmetric
model without R-parity (RPV-MSSM) which contributes to A_{FB}^t via
sparticle-mediated t-channel process d d_bar-> t t_bar; the other is the
third-generation enhanced left-right model (LR model) which contributes to
A_{FB}^t via Z'-mediated t-channel or s-channel processes. We find that in the
parameter space allowed by the tt_bar production rate and the tt_bar invariant
mass distribution at the Tevatron, the LR model can enhance A_{FB}^t to within
the 2-sigma region of the Tevatron data for the major part of the parameter
space, and in optimal case A_{FB}^t can reach 12% which is slightly below the
1-sigma lower bound. For the RPV-MSSM, only in a narrow part of the parameter
space can the \lambda'' couplings enhance A_{FB}^t to within the 2-sigma region
while the \lambda' couplings just produce negative contributions to worsen the
fit.Comment: Version in PRD (RPV-MSSM lambda" effects added
Explanation of the ATLAS Z-peaked excess by squark pair production in the NMSSM
The ATLAS collaboration recently reported a excess in the
leptonic- channel. We intend to interpret this excess by
squark pair production in the Next-to-Minimal Supersymmetric Standard Model
(NMSSM). The decay chain we employ is , where and denote the
lightest and the next-to-lightest neutralinos with singlino and bino as their
dominant components respectively. Our simulations indicate that after
considering the constraints from the ATLAS searches for
signal the central value of the excess can be obtained for , and if the constraint from the CMS on- search is
further considered, more than 10 signal events are still attainable for
. Compared with the interpretation by
gluino pair production, the squark explanation allows for a significantly wider
range of as well as a less compressed SUSY mass spectrum. We
also show that the squark explanation will be readily tested at the initial
stage of the 14 TeV LHC.Comment: 19 pages, 4 figure
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