214 research outputs found
A process very similar to multifractional Brownian motion
In Ayache and Taqqu (2005), the multifractional Brownian (mBm) motion is
obtained by replacing the constant parameter of the fractional Brownian
motion (fBm) by a smooth enough functional parameter depending on the
time . Here, we consider the process obtained by replacing in the
wavelet expansion of the fBm the index by a function depending on
the dyadic point . This process was introduced in Benassi et al (2000)
to model fBm with piece-wise constant Hurst index and continuous paths. In this
work, we investigate the case where the functional parameter satisfies an
uniform H\"older condition of order \beta>\sup_{t\in \rit} H(t) and ones
shows that, in this case, the process is very similar to the mBm in the
following senses: i) the difference between and a mBm satisfies an uniform
H\"older condition of order ; ii) as a by product, one
deduces that at each point the pointwise H\"older exponent of is
and that is tangent to a fBm with Hurst parameter .Comment: 18 page
Borgoña y Franco Condado: estrechando lazos para una mayor cohesión económica, social y territorial
El ISSN corresponde a la versión electrónica del documentoPatrick Ayache, vicepresidente responsable de Asuntos Europeos e Internacionales en la región de Borgoña-Franco Condado, explica cómo la fusión está cambiando todos los aspectos de la cohesión territorial
Information-Theoretic Active Learning for Content-Based Image Retrieval
We propose Information-Theoretic Active Learning (ITAL), a novel batch-mode
active learning method for binary classification, and apply it for acquiring
meaningful user feedback in the context of content-based image retrieval.
Instead of combining different heuristics such as uncertainty, diversity, or
density, our method is based on maximizing the mutual information between the
predicted relevance of the images and the expected user feedback regarding the
selected batch. We propose suitable approximations to this computationally
demanding problem and also integrate an explicit model of user behavior that
accounts for possible incorrect labels and unnameable instances. Furthermore,
our approach does not only take the structure of the data but also the expected
model output change caused by the user feedback into account. In contrast to
other methods, ITAL turns out to be highly flexible and provides
state-of-the-art performance across various datasets, such as MIRFLICKR and
ImageNet.Comment: GCPR 2018 paper (14 pages text + 2 pages references + 6 pages
appendix
Thermopower in the strongly overdoped region of single-layer Bi2Sr2CuO6+d superconductor
The evolution of the thermoelectric power S(T) with doping, p, of
single-layer Bi2Sr2CuO6+d ceramics in the strongly overdoped region is studied
in detail. Analysis in term of drag and diffusion contributions indicates a
departure of the diffusion from the T-linear metallic behavior. This effect is
increased in the strongly overdoped range (p~0.2-0.28) and should reflect the
proximity of some topological change.Comment: 4 pages, 4 figure
Anomalous electronic susceptibility in Bi2Sr2CuO6+d and comparison with other overdoped cuprates
We report magnetic susceptibility performed on overdoped Bi2Sr2CuO6+d powders
as a function of oxygen doping d and temperature T. The decrease of the spin
susceptibility with increasing T is confirmed. At sufficient high temperature,
the spin susceptibility Chi_s presents an unusual linear temperature dependence
Chi_s ~ Chi_s0 -Chi_1 T. Moreover, a linear correlation between Chi_1 and
Chi_s0 for increasing hole concentration is displayed. A temperature Tchi,
independent of hole doping characterizes this scaling. Comparison with other
cuprates of the literature(LSCO, Tl-2201 and Bi-2212), over the same overdoped
range, shows similarities with above results. These non conventional metal
features will be discussed in terms of a singular narrow-band structure.Comment: 16 pages, 4 figure
Incremental Multiple Classifier Active Learning for Concept Indexing in Images and Videos
Regular Papers: Multimedia Indexing and MiningInternational audienceActive learning with multiple classifiers has shown good performance for concept indexing in images or video shots in the case of highly imbalanced data. It involves however a large number of computations. In this paper, we propose a new incremental active learning algorithm based on multiple SVM for image and video annotation. The experimental result show that the best performance (MAP) is reached when 15-30% of the corpus is annotated and the new method can achieve almost the same precision while saving 50 to 63% of the computation time
Retarding Sub- and Accelerating Super-Diffusion Governed by Distributed Order Fractional Diffusion Equations
We propose diffusion-like equations with time and space fractional
derivatives of the distributed order for the kinetic description of anomalous
diffusion and relaxation phenomena, whose diffusion exponent varies with time
and which, correspondingly, can not be viewed as self-affine random processes
possessing a unique Hurst exponent. We prove the positivity of the solutions of
the proposed equations and establish the relation to the Continuous Time Random
Walk theory. We show that the distributed order time fractional diffusion
equation describes the sub-diffusion random process which is subordinated to
the Wiener process and whose diffusion exponent diminishes in time (retarding
sub-diffusion) leading to superslow diffusion, for which the square
displacement grows logarithmically in time. We also demonstrate that the
distributed order space fractional diffusion equation describes super-diffusion
phenomena when the diffusion exponent grows in time (accelerating
super-diffusion).Comment: 11 pages, LaTe
Efficient registration of stereo images by matching graph descriptions of edge segments
Optical properties of an effective one-band Hubbard model for the cuprates
We study the Cu and O spectral density of states and the optical conductivity
of CuO_2 planes using an effective generalized one-band Hubbard model derived
from the extended three-band Hubbard model. We solve exactly a square cluster
of 10 unit cells and average the results over all possible boundary conditions,
what leads to smooth functions of frequency. Upon doping, the Fermi energy
jumps to Zhang-Rice states which are connected to the rest of the valence band
(in contrast to an isolated new band in the middle of the gap). The transfer of
spectral weight depends on the parameters of the original three-band model not
only through the one-band effective parameters but also through the relevant
matrix elements. We discuss the evolution of the gap upon doping. The optical
conductivity of the doped system shows a mid-infrared peak due to intraband
transitions, a pseudogap and a high frequency part related to interband
transitions. Its shape and integrated weight up to a given frequency (including
the Drude weight) agree qualitatively with experiments in the cuprates for low
to moderate doping levels, but significant deviations exist for doping .Comment: 11 pages (tex), 14 figures (ps
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