53,997 research outputs found
Chiral Structure of Vector and Axial-Vector Tetraquark Currents
We investigate the chiral structure of local vector and axial-vector
tetraquark currents, and study their chiral transformation properties. We
consider the charge-conjugation parity and classify all the isovector vector
and axial-vector local tetraquark currents of quantum numbers
I(G)J(PC)=1(-)1(-+), I(G)J(PC)=1(+)1(--), I(G)J(PC)=1(-)1(++) and
I(G)J(PC)=1(+)1(+-). We find that there is a one to one correspondence among
them. Using these currents, we perform QCD sum rule analyses. Our results
suggest that there is a missing b1 state having I(G)J(PC)=1(+)1(+-) and a mass
around 1.47-1.66 GeV.Comment: 27 pages, 8 figures, 3 tables, accepted by EPJC. arXiv admin note:
text overlap with arXiv:1311.443
Frictional interface crack-tip singular stress field in anisotropic
This study presents the asymptotic displacement and stress fields at the crack tip of frictional interface where slip can occur along the interface between two anisotropic composite laminates. The results show that real values corresponding to the order of stress singularities may exit at the crack tip of the frictional interface between two anisotropic layers. The order of stress singularity largely depends on the coefficient of friction within the interface and the material properties of anisotropic composite laminates such as fibre orientations
Extracting Noun Phrases from Large-Scale Texts: A Hybrid Approach and Its Automatic Evaluation
To acquire noun phrases from running texts is useful for many applications,
such as word grouping,terminology indexing, etc. The reported literatures adopt
pure probabilistic approach, or pure rule-based noun phrases grammar to tackle
this problem. In this paper, we apply a probabilistic chunker to deciding the
implicit boundaries of constituents and utilize the linguistic knowledge to
extract the noun phrases by a finite state mechanism. The test texts are
SUSANNE Corpus and the results are evaluated by comparing the parse field of
SUSANNE Corpus automatically. The results of this preliminary experiment are
encouraging.Comment: 8 pages, Postscript file, Unix compressed, uuencode
On Weak Topology for Optimal Control of Switched Nonlinear Systems
Optimal control of switched systems is challenging due to the discrete nature
of the switching control input. The embedding-based approach addresses this
challenge by solving a corresponding relaxed optimal control problem with only
continuous inputs, and then projecting the relaxed solution back to obtain the
optimal switching solution of the original problem. This paper presents a novel
idea that views the embedding-based approach as a change of topology over the
optimization space, resulting in a general procedure to construct a switched
optimal control algorithm with guaranteed convergence to a local optimizer. Our
result provides a unified topology based framework for the analysis and design
of various embedding-based algorithms in solving the switched optimal control
problem and includes many existing methods as special cases
- …