29,395 research outputs found
Improving information filtering via network manipulation
Recommender system is a very promising way to address the problem of
overabundant information for online users. Though the information filtering for
the online commercial systems received much attention recently, almost all of
the previous works are dedicated to design new algorithms and consider the
user-item bipartite networks as given and constant information. However, many
problems for recommender systems such as the cold-start problem (i.e. low
recommendation accuracy for the small degree items) are actually due to the
limitation of the underlying user-item bipartite networks. In this letter, we
propose a strategy to enhance the performance of the already existing
recommendation algorithms by directly manipulating the user-item bipartite
networks, namely adding some virtual connections to the networks. Numerical
analyses on two benchmark data sets, MovieLens and Netflix, show that our
method can remarkably improve the recommendation performance. Specifically, it
not only improve the recommendations accuracy (especially for the small degree
items), but also help the recommender systems generate more diverse and novel
recommendations.Comment: 6 pages, 5 figure
Integrable dispersionless KdV hierarchy with sources
An integrable dispersionless KdV hierarchy with sources (dKdVHWS) is derived.
Lax pair equations and bi-Hamiltonian formulation for dKdVHWS are formulated.
Hodograph solution for the dispersionless KdV equation with sources (dKdVWS) is
obtained via hodograph transformation. Furthermore, the dispersionless
Gelfand-Dickey hierarchy with sources (dGDHWS) is presented.Comment: 15 pages, to be published in J. Phys. A: Math. Ge
Morphology and thermal conductivity of model organic aerogels
The intersection volume of two independent 2-level cut Gaussian random fields
is proposed to model the open-cell microstructure of organic aerogels. The
experimentally measured X-ray scattering intensity, surface area and solid
thermal conductivity of both polymeric and colloidal organic aerogels can be
accounted for by the model.Comment: 5 pages. RevTex with 4 encapsulated figures. Higher resolution
figures have been submitted for publication. To be published in Phys. Rev. E
(Rapid Comm.). email, [email protected]
On the Toda Lattice Equation with Self-Consistent Sources
The Toda lattice hierarchy with self-consistent sources and their Lax
representation are derived. We construct a forward Darboux transformation (FDT)
with arbitrary functions of time and a generalized forward Darboux
transformation (GFDT) for Toda lattice with self-consistent sources (TLSCS),
which can serve as a non-auto-Backlund transformation between TLSCS with
different degrees of sources. With the help of such DT, we can construct many
type of solutions to TLSCS, such as rational solution, solitons, positons,
negetons, and soliton-positons, soliton-negatons, positon-negatons etc., and
study properties and interactions of these solutions.Comment: 20 page
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