25,918 research outputs found
Truss Decomposition in Massive Networks
The k-truss is a type of cohesive subgraphs proposed recently for the study
of networks. While the problem of computing most cohesive subgraphs is NP-hard,
there exists a polynomial time algorithm for computing k-truss. Compared with
k-core which is also efficient to compute, k-truss represents the "core" of a
k-core that keeps the key information of, while filtering out less important
information from, the k-core. However, existing algorithms for computing
k-truss are inefficient for handling today's massive networks. We first improve
the existing in-memory algorithm for computing k-truss in networks of moderate
size. Then, we propose two I/O-efficient algorithms to handle massive networks
that cannot fit in main memory. Our experiments on real datasets verify the
efficiency of our algorithms and the value of k-truss.Comment: VLDB201
Analyses of celestial pole offsets with VLBI, LLR, and optical observations
This work aims to explore the possibilities of determining the long-period
part of the precession-nutation of the Earth with techniques other than very
long baseline interferometry (VLBI). Lunar laser ranging (LLR) is chosen for
its relatively high accuracy and long period. Results of previous studies could
be updated using the latest data with generally higher quality, which would
also add ten years to the total time span. Historical optical data are also
analyzed for their rather long time-coverage to determine whether it is
possible to improve the current Earth precession-nutation model
Switching of both local ferroelectric and magnetic domains in multiferroic Bi0.9La0.1FeO3 thin film by mechanical force
Cross-coupling of ordering parameters in multiferroic materials by multiple
external stimuli other than electric field and magnetic field is highly
desirable from both practical application and fundamental study points of view.
Recently, mechanical force has attracted great attention in switching of
ferroic ordering parameters via electro-elastic coupling in ferroelectric
materials. In this work, mechanical force induced polarization and
magnetization switching were investigated in a polycrystalline multiferroic
Bi0.9La0.1FeO3 thin film using a scanning probe microscopy system. The
piezoresponse force microscopy and magnetic force microscopy responses suggest
that both the ferroelectric domains and the magnetic domains in Bi0.9La0.1FeO3
film could be switched by mechanical force as well as electric field. High
strain gradient created by mechanical force is demonstrated as able to induce
ferroelastic switching and thus induce both ferroelectric dipole and magnetic
spin flipping in our thin film, as a consequence of electro-elastic coupling
and magneto-electric coupling. The demonstration of mechanical force control of
both the ferroelectric and the magnetic domains at room temperature provides a
new freedom for manipulation of multiferroics and could result in devices with
novel functionalities
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