1,511 research outputs found
Boosting Handwriting Text Recognition in Small Databases with Transfer Learning
In this paper we deal with the offline handwriting text recognition (HTR)
problem with reduced training datasets. Recent HTR solutions based on
artificial neural networks exhibit remarkable solutions in referenced
databases. These deep learning neural networks are composed of both
convolutional (CNN) and long short-term memory recurrent units (LSTM). In
addition, connectionist temporal classification (CTC) is the key to avoid
segmentation at character level, greatly facilitating the labeling task. One of
the main drawbacks of the CNNLSTM-CTC (CLC) solutions is that they need a
considerable part of the text to be transcribed for every type of calligraphy,
typically in the order of a few thousands of lines. Furthermore, in some
scenarios the text to transcribe is not that long, e.g. in the Washington
database. The CLC typically overfits for this reduced number of training
samples. Our proposal is based on the transfer learning (TL) from the
parameters learned with a bigger database. We first investigate, for a reduced
and fixed number of training samples, 350 lines, how the learning from a large
database, the IAM, can be transferred to the learning of the CLC of a reduced
database, Washington. We focus on which layers of the network could be not
re-trained. We conclude that the best solution is to re-train the whole CLC
parameters initialized to the values obtained after the training of the CLC
from the larger database. We also investigate results when the training size is
further reduced. The differences in the CER are more remarkable when training
with just 350 lines, a CER of 3.3% is achieved with TL while we have a CER of
18.2% when training from scratch. As a byproduct, the learning times are quite
reduced. Similar good results are obtained from the Parzival database when
trained with this reduced number of lines and this new approach.Comment: ICFHR 2018 Conferenc
Higher order Whitehead products and structures on the homology of a DGL
We detect higher order Whitehead products on the homology of a
differential graded Lie algebra in terms of higher brackets in the
transferred structure on via a given homotopy retraction of
onto .Comment: New references and minor correction
Tree-structure Expectation Propagation for Decoding LDPC codes over Binary Erasure Channels
Expectation Propagation is a generalization to Belief Propagation (BP) in two
ways. First, it can be used with any exponential family distribution over the
cliques in the graph. Second, it can impose additional constraints on the
marginal distributions. We use this second property to impose pair-wise
marginal distribution constraints in some check nodes of the LDPC Tanner graph.
These additional constraints allow decoding the received codeword when the BP
decoder gets stuck. In this paper, we first present the new decoding algorithm,
whose complexity is identical to the BP decoder, and we then prove that it is
able to decode codewords with a larger fraction of erasures, as the block size
tends to infinity. The proposed algorithm can be also understood as a
simplification of the Maxwell decoder, but without its computational
complexity. We also illustrate that the new algorithm outperforms the BP
decoder for finite block-siz
Turbo EP-based Equalization: a Filter-Type Implementation
This manuscript has been submitted to Transactions on Communications on
September 7, 2017; revised on January 10, 2018 and March 27, 2018; and accepted
on April 25, 2018
We propose a novel filter-type equalizer to improve the solution of the
linear minimum-mean squared-error (LMMSE) turbo equalizer, with computational
complexity constrained to be quadratic in the filter length. When high-order
modulations and/or large memory channels are used the optimal BCJR equalizer is
unavailable, due to its computational complexity. In this scenario, the
filter-type LMMSE turbo equalization exhibits a good performance compared to
other approximations. In this paper, we show that this solution can be
significantly improved by using expectation propagation (EP) in the estimation
of the a posteriori probabilities. First, it yields a more accurate estimation
of the extrinsic distribution to be sent to the channel decoder. Second,
compared to other solutions based on EP the computational complexity of the
proposed solution is constrained to be quadratic in the length of the finite
impulse response (FIR). In addition, we review previous EP-based turbo
equalization implementations. Instead of considering default uniform priors we
exploit the outputs of the decoder. Some simulation results are included to
show that this new EP-based filter remarkably outperforms the turbo approach of
previous versions of the EP algorithm and also improves the LMMSE solution,
with and without turbo equalization
Trace elements and C and N isotope composition in two mushroom species from a mine-spill contaminated site
Fungi play a key role in the functioning of soil in terrestrial ecosystems, and in particular in the
remediation of degraded soils. The contribution of fungi to carbon and nutrient cycles, along with
their capability to mobilise soil trace elements, is well-known. However, the importance of life history
strategy for these functions has not yet been thoroughly studied. This study explored the soil-fungi
relationship of two wild edible fungi, the ectomycorrhizal Laccaria laccata and the saprotroph
Volvopluteus gloiocephalus. Fruiting bodies and surrounding soils in a mine-spill contaminated area
were analysed. Isotope analyses revealed Laccaria laccata fruiting bodies were 15N-enriched when
compared to Volvopluteus gloiocephalus, likely due to the transfer of 15N-depleted compounds to their
host plant. Moreover, Laccaria laccata fruiting bodies δ13C values were closer to host plant values than
surrounding soil, while Volvopluteus gloiocephalus matched the δ13C composition to that of the soil.
Fungal species presented high bioaccumulation and concentrations of Cd and Cu in their fruiting bodies.
Human consumption of these fruiting bodies may represent a toxicological risk due to their elevated Cd
concentrations
Coordinating heterogeneous IoT devices by means of the centralized vision of the SDN controller
The IoT (Internet of Things) has become a reality during recent years. The desire of having everything connected to the Internet results in clearly identified benefits that will impact on socio economic development. However, the exponential growth in the number of IoT devices and their heterogeneity open new challenges that must be carefully studied. Coordination among devices to adapt them to their users' context usually requires high volumes of data to be exchanged with the cloud. In order to reduce unnecessary communications and network overhead, this paper proposes a novel network architecture based on the Software-Defined Networking paradigm that allows IoT devices coordinate and adapt them within the scope of a particular context.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
Tree-Structure Expectation Propagation for LDPC Decoding over the BEC
We present the tree-structure expectation propagation (Tree-EP) algorithm to
decode low-density parity-check (LDPC) codes over discrete memoryless channels
(DMCs). EP generalizes belief propagation (BP) in two ways. First, it can be
used with any exponential family distribution over the cliques in the graph.
Second, it can impose additional constraints on the marginal distributions. We
use this second property to impose pair-wise marginal constraints over pairs of
variables connected to a check node of the LDPC code's Tanner graph. Thanks to
these additional constraints, the Tree-EP marginal estimates for each variable
in the graph are more accurate than those provided by BP. We also reformulate
the Tree-EP algorithm for the binary erasure channel (BEC) as a peeling-type
algorithm (TEP) and we show that the algorithm has the same computational
complexity as BP and it decodes a higher fraction of errors. We describe the
TEP decoding process by a set of differential equations that represents the
expected residual graph evolution as a function of the code parameters. The
solution of these equations is used to predict the TEP decoder performance in
both the asymptotic regime and the finite-length regime over the BEC. While the
asymptotic threshold of the TEP decoder is the same as the BP decoder for
regular and optimized codes, we propose a scaling law (SL) for finite-length
LDPC codes, which accurately approximates the TEP improved performance and
facilitates its optimization
Growth of Single-Crystal LiNbO<sub>3</sub> Particles by Aerosol-Assisted Chemical Vapor Deposition Method
Adjusting nucleation conditions, an effective shape and size control in the preparation of single-crystal lithium niobate nanoparticles by aerosol-assisted chemical vapor deposition method was demonstrated. The effect of the most relevant parameters leading to nanocrystals taking a specific shape or size once they are synthesized was analyzed. This has allowed us to demonstrate that it is possible to control the size and morphology of particles prepared adjusting the nucleation conditions. The synthesized nanocrystals showed different morphologies including quasi-cubic, tetrahedral, polyhedral, and hexagonal shapes, with characteristic sizes ranging from a few tens to a few hundred nanometers. However, rod-like structures with characteristic lengths ranging from 3 to 5 μm were also obtained. The structural and morphological characterization by X-ray diffraction and high-resolution electron microscopy techniques revealed the single-crystal nature of the synthesized particles
Neuroscience and subjectivity. A proposal for cooperation between neuroscience and some philosophical traditions
One of the main challenges of biology consists in articulating a coherent view of the central nervous system and its structure.
To this end, neuroscience has emerged as an interdisciplinary project which looks to integrate the different disciplines
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