95,565 research outputs found
A Java implementation of Coordination Rules as ECA Rules
This paper gives an insight in to the design and implementation of the coordination rules as ECA rules. The language specifications of the ECA rules were designed and the corresponding implementation of the same using JAVA as been partially done. The paper also hints about the future work in this area which deals with embedding this code in JXTA, thus enabling to form a P2P layer with JXTA as the back bone
Parallel matrix inversion techniques
In this paper, we present techniques for inverting sparse, symmetric and positive definite matrices on parallel and distributed computers. We propose two algorithms, one for SIMD implementation and the other for MIMD implementation. These algorithms are modified versions of Gaussian elimination and they take into account the sparseness of the matrix. Our algorithms perform better than the general parallel Gaussian elimination algorithm. In order to demonstrate the usefulness of our technique, we implemented the snake problem using our sparse matrix algorithm. Our studies reveal that the proposed sparse matrix inversion algorithm significantly reduces the time taken for obtaining the solution of the snake problem. In this paper, we present the results of our experimental work
Parsimonious Labeling
We propose a new family of discrete energy minimization problems, which we
call parsimonious labeling. Specifically, our energy functional consists of
unary potentials and high-order clique potentials. While the unary potentials
are arbitrary, the clique potentials are proportional to the {\em diversity} of
set of the unique labels assigned to the clique. Intuitively, our energy
functional encourages the labeling to be parsimonious, that is, use as few
labels as possible. This in turn allows us to capture useful cues for important
computer vision applications such as stereo correspondence and image denoising.
Furthermore, we propose an efficient graph-cuts based algorithm for the
parsimonious labeling problem that provides strong theoretical guarantees on
the quality of the solution. Our algorithm consists of three steps. First, we
approximate a given diversity using a mixture of a novel hierarchical
Potts model. Second, we use a divide-and-conquer approach for each mixture
component, where each subproblem is solved using an effficient
-expansion algorithm. This provides us with a small number of putative
labelings, one for each mixture component. Third, we choose the best putative
labeling in terms of the energy value. Using both sythetic and standard real
datasets, we show that our algorithm significantly outperforms other graph-cuts
based approaches
Polymer precursors for ceramic matrix composites
The synthesis and characterization of a polycyclohexasilane is reported. Because of its cyclic structure, it is anticipated that this polymer might serve as a precursor to SIC having a high char yield with little rearrangement to form small, volatile cyclic silanes, and, as such, would be of interest as a precursor to SiC composite matrices and fibers, or as a binder in ceramic processing. Several approaches to the synthesis of a bifunctional cyclic monomer were attempted; the most successful of these was metal coupling of PhMeSiCl2 and Me2SiCl2. The procedure gives six-membered ring compounds with all degrees of phenyl substitution, from none to hexaphenyl. The compounds with from 0-2 groups were isolated and characterized. The fraction with degree of phenyl substitution equal to 2, a mixture of cis and trans 1,2-; 1,3-; and 1,4 isomers, was isolated in 32 percent yield. Pure 1,4 diphenyldecamethylcyclohexasilane was isolated from the mixed diphenyl compounds and characterized. Diphenyldecamethylcyclohexasilanes were dephenylated to dichlorodecamethylcyclohexasilanes by treating with H2SO4.NH4Cl in benzene. The latter were purified and polymerized by reacting with sodium in toluene. The polymers were characterized by HPGPC, elemental analysis, proton NMR, and IR. Thermogravimetric analyses were carried out on the polymers. As the yield of residual SiC was low, polymers were heat treated to increase the residual char yield. As high as 51.52 percent residual char yield was obtained in one case
Liouville Numbers and Schanuel's Conjecture
In this paper, using an argument of P. Erdos, K. Alniacik and E. Saias, we
extend earlier results on Liouville numbers, due to P. Erdos, G.J. Rieger, W.
Schwarz, K. Alniacik, E. Saias, E.B. Burger. We also produce new results of
algebraic independence related with Liouville numbers and Schanuel's
Conjecture, in the framework of G delta-subsets.Comment: Archiv der Math., to appea
Liouville numbers, Liouville sets and Liouville fields
Following earlier work by E.Maillet 100 years ago, we introduce the
definition of a Liouville set, which extends the definition of a Liouville
number. We also define a Liouville field, which is a field generated by a
Liouville set. Any Liouville number belongs to a Liouville set S having the
power of continuum and such that the union of S with the rational number field
is a Liouville field.Comment: Proceedings of the American Mathematical Society, to appea
Taming of Modulation Instability by Spatio-Temporal Modulation of the Potential
Spontaneous pattern formation in a variety of spatially extended nonlinear
system always occurs through a modulation instability: homogeneous state of the
system becomes unstable with respect to growing modulation modes. Therefore,
the manipulation of the modulation instability is of primary importance in
controlling and manipulating the character of spatial patterns initiated by
that instability. We show that the spatio-temporal periodic modulation of the
potential of the spatially extended system results in a modification of its
pattern forming instability. Depending on the modulation character the
instability can be partially suppressed, can change its spectrum (for instance
the long wave instability can transform into short wave instability), can split
into two, or can be completely eliminated. The latter result is of especial
practical interest, as can be used to stabilize the intrinsically unstable
system. The result bears general character, as it is shown here on a universal
model of Complex Ginzburg-Landau equations in one and two spatial dimension
(and time). The physical mechanism of instability suppression can be applied to
a variety of intrinsically unstable dissipative systems, like self-focusing
lasers, reaction-diffusion systems, as well as in unstable conservative
systems, like attractive Bose Einstein condensates.Comment: 5 pages, 4 figures, 1 supplementary video fil
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