366 research outputs found
A data mining approach for location prediction in mobile environments
Cataloged from PDF version of article.Mobility prediction is one of the most essential issues that need to be explored for mobility management
in mobile computing systems. In this paper, we propose a new algorithm for predicting the next inter-cell
movement of a mobile user in a Personal Communication Systems network. In the first phase of our threephase
algorithm, user mobility patterns are mined from the history of mobile user trajectories. In the second
phase, mobility rules are extracted from these patterns, and in the last phase, mobility predictions are
accomplished by using these rules. The performance of the proposed algorithm is evaluated through simulation
as compared to two other prediction methods. The performance results obtained in terms of Precision
and Recall indicate that our method can make more accurate predictions than the other methods.
2004 Elsevier B.V. All rights reserved
Scalable Mining of Common Routes in Mobile Communication Network Traffic Data
A probabilistic method for inferring common routes from mobile communication network traffic data is presented. Besides providing mobility information, valuable in a multitude of application areas, the method has the dual purpose of enabling efficient coarse-graining as well as anonymisation by mapping individual sequences onto common routes. The approach is to represent spatial trajectories by Cell ID sequences that are grouped into routes using locality-sensitive hashing and graph clustering. The method is demonstrated to be scalable, and to accurately group sequences using an evaluation set of GPS tagged data
Optical and excitonic properties of transition metal oxide perovskites by the Bethe-Salpeter equation
We present a systematic investigation of the role and importance of excitonic effects on the optical propertiesof transitions metal oxide perovskites. A representative set of 14 compounds has been selected, including3d(SrTiO3, LaScO3,LaTiO3,LaVO3,LaCrO3,LaMnO3, LaFeO3, and SrMnO3), 4d(SrZrO3, SrTcO3,andCa2RuO4)and5d(SrHfO3,KTaO3, and NaOsO3) perovskites, covering a band gap ranging from 0.1 eVto 6.1 eV and exhibiting different electronic, structural, and magnetic properties. Optical conductivities andoptical transitions including electron-hole interactions are calculated through the solution of the Bethe-Salpeterequation (BSE) with quasiparticle energies evaluated by the single-shotG0W0approximation. The excitonbinding energies are computed by means of a model BSE, carefully benchmarked against the full-BSE method,in order to obtain well-converged results in terms ofk-point sampling. The predicted results are compared withavailable measured data, with an overall satisfactory agreement between theory and experiment
Single top or bottom production associated with a scalar in \gamma p collision as a probe of topcolor-assisted technicolor
In the framework of the topcolor-assisted technicolor (TC2) models, we study
the productions of a single top or bottom quark associated with a scalar in
\gamma-p collision, which proceed via the subprocesses c\gamma -> t\pi_t^0,
c\gamma -> t h_t^0 and c\gamma -> b\pi^+_t mediated by the anomalous top or
bottom coupling tc\pi_t^0, tch_t^0 and bc\pi_t^+. These productions, while
extremely suppressed in the Standard Model, are found to be significantly
enhanced in the large part of the TC2 parameter space, especially the
production via c\gamma -> b\pi^+ can have a cross section of 100 fb, which may
be accessible and allow for a test of the TC2 models.Comment: 13 pages, 4 figures, comments and references adde
Determining the Electron-Phonon Coupling Strength in Correlated Electron Systems from Resonant Inelastic X-ray Scattering
We show that high resolution Resonant Inelastic X-ray Scattering (RIXS)
provides direct, element-specific and momentum-resolved information on the
electron-phonon (e-p) coupling strength. Our theoretical analysis demonstrates
that the e-p coupling can be extracted from RIXS spectra by determining the
differential phonon scattering cross section. An alternative, very direct
manner to extract the coupling is to use the one and two-phonon loss ratio,
which is governed by the e-p coupling strength and the core-hole life-time.
This allows measurement of the e-p coupling on an absolute energy scale.Comment: 4 pages, 3 figure
Spin waves and spin-state transitions in a ruthenate high-temperature antiferromagnet
Ruthenium compounds play prominent roles in materials research ranging from
oxide electronics to catalysis, and serve as a platform for fundamental
concepts such as spin-triplet superconductivity, Kitaev spin-liquids, and
solid-state analogues of the Higgs mode in particle physics. However, basic
questions about the electronic structure of ruthenates remain unanswered,
because several key parameters (including the Hund's-rule, spin-orbit, and
exchange interactions) are comparable in magnitude, and their interplay is
poorly understood - partly due to difficulties in synthesizing sizable single
crystals for spectroscopic experiments. Here we introduce a resonant inelastic
x-ray scattering (RIXS) technique capable of probing collective modes in
microcrystals of -electron materials. We present a comprehensive set of
data on spin waves and spin-state transitions in the honeycomb antiferromagnet
SrRuO, which possesses an unusually high N\'eel temperature. The
new RIXS method provides fresh insight into the unconventional magnetism of
SrRuO, and enables momentum-resolved spectroscopy of a large class
of transition-metal compounds.Comment: The original submitted version of the published manuscript.
https://www.nature.com/articles/s41563-019-0327-
Clustering mobile trajectories for resource allocation in mobile environments
The recent developments in computer and communication technologies gave rise to Personal Communication Systems. Due to the nature of the PCS, the bandwidth allocation problem arises, which is based on the notion of bandwidth-on-demand. We deal with the problem of how to predict the position of a mobile client. We propose a new algorithm, called DCP, to discover user mobility patterns from collections of recorded mobile trajectories and use them for the prediction of movements and dynamic allocation of resources. The performance of the proposed algorithm is examined against two baseline algorithms. The simulation results illustrate that the proposed algorithm achieves recall that is comparable to that of the baseline algorithms and substantial improvement in precision. This improvement guarantees very good predictions for resource allocation with the advantage of very low resource consumption. © Springer-Verlag Berlin Heidelberg 2003
X-ray resonant photoexcitation: line widths and energies of K{\alpha} transitions in highly charged Fe ions
Photoabsorption by and fluorescence of the K{\alpha} transitions in highly
charged iron ions are essential mechanisms for X-ray radiation transfer in
astrophysical environments. We study photoabsorption due to the main K{\alpha}
transitions in highly charged iron ions from heliumlike to fluorinelike (Fe
24+...17+) using monochromatic X-rays around 6.6 keV at the PETRA III
synchrotron photon source. Natural linewidths were determined with hitherto
unattained accuracy. The observed transitions are of particular interest for
the understanding of photoexcited plasmas found in X-ray binaries and active
galactic nuclei.Comment: Revised versio
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