27,636 research outputs found
Supersymmetric KdV equation: Darboux transformation and discrete systems
For the supersymmetric KdV equation, a proper Darboux transformation is
presented. This Darboux transformation leads to the B\"{a}cklund transformation
found early by Liu and Xie \cite{liu2}. The Darboux transformation and the
related B\"{a}cklund transformation are used to construct integrable super
differential-difference and difference-difference systems. The continuum limits
of these discrete systems and of their Lax pairs are also considered.Comment: 13pages, submitted to Journal of Physics
Representation of perfectly reconstructed octave decomposition filter banks with set of decimators {2,4,4} via tree structure
In this letter, we prove that a filter bank with set of decimators {2,4,4} achieves perfect reconstruction if and only if it can be represented via a tree structure and each branch of the tree structure achieves perfect reconstruction
Remote downconversion with wavelength reuse for the radio/fiber uplink connection
The authors present a novel technology for uplink transmission in radio-over-fiber distribution systems. The technique employs remote downconversion of the uplink data to intermediate frequency (IF) in the base station (BS). The local oscillator signal for the downconversion is optically generated in the central station (CS) and sent to the BS via optical fiber. The IF uplink data is then modulated onto an optical carrier, retrieved from the downlink signal, and sent to the CS, where the baseband conversion takes place. By employing this method of uplink connection, simplicity and cost efficiency of the BS is achieved
Global well-posedness for the Gross-Pitaevskii equation with an angular momentum rotational term in three dimensions
In this paper, we establish the global well-posedness of the Cauchy problem
for the Gross-Pitaevskii equation with an angular momentum rotational term in
which the angular velocity is equal to the isotropic trapping frequency in the
space \Real^3.Comment: 11 page
Interacting dark energy, holographic principle and coincidence problem
The interacting and holographic dark energy models involve two important
quantities. One is the characteristic size of the holographic bound and the
other is the coupling term of the interaction between dark energy and dark
matter. Rather than fixing either of them, we present a detailed study of
theoretical relationships among these quantities and cosmological parameters as
well as observational constraints in a very general formalism. In particular,
we argue that the ratio of dark matter to dark energy density depends on the
choice of these two quantities, thus providing a mechanism to change the
evolution history of the ratio from that in standard cosmology such that the
coincidence problem may be solved. We investigate this problem in detail and
construct explicit models to demonstrate that it may be alleviated provided
that the interacting term and the characteristic size of holographic bound are
appropriately specified. Furthermore, these models are well fitted with the
current observation at least in the low red-shift region.Comment: 20 pages, 3 figure
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