20,136 research outputs found
A Survey of Adaptive Resonance Theory Neural Network Models for Engineering Applications
This survey samples from the ever-growing family of adaptive resonance theory
(ART) neural network models used to perform the three primary machine learning
modalities, namely, unsupervised, supervised and reinforcement learning. It
comprises a representative list from classic to modern ART models, thereby
painting a general picture of the architectures developed by researchers over
the past 30 years. The learning dynamics of these ART models are briefly
described, and their distinctive characteristics such as code representation,
long-term memory and corresponding geometric interpretation are discussed.
Useful engineering properties of ART (speed, configurability, explainability,
parallelization and hardware implementation) are examined along with current
challenges. Finally, a compilation of online software libraries is provided. It
is expected that this overview will be helpful to new and seasoned ART
researchers
Deep Learning How to Fit an Intravoxel Incoherent Motion Model to Diffusion-Weighted MRI
Purpose: This prospective clinical study assesses the feasibility of training
a deep neural network (DNN) for intravoxel incoherent motion (IVIM) model
fitting to diffusion-weighted magnetic resonance imaging (DW-MRI) data and
evaluates its performance. Methods: In May 2011, ten male volunteers (age
range: 29 to 53 years, mean: 37 years) underwent DW-MRI of the upper abdomen on
1.5T and 3.0T magnetic resonance scanners. Regions of interest in the left and
right liver lobe, pancreas, spleen, renal cortex, and renal medulla were
delineated independently by two readers. DNNs were trained for IVIM model
fitting using these data; results were compared to least-squares and Bayesian
approaches to IVIM fitting. Intraclass Correlation Coefficients (ICC) were used
to assess consistency of measurements between readers. Intersubject variability
was evaluated using Coefficients of Variation (CV). The fitting error was
calculated based on simulated data and the average fitting time of each method
was recorded. Results: DNNs were trained successfully for IVIM parameter
estimation. This approach was associated with high consistency between the two
readers (ICCs between 50 and 97%), low intersubject variability of estimated
parameter values (CVs between 9.2 and 28.4), and the lowest error when compared
with least-squares and Bayesian approaches. Fitting by DNNs was several orders
of magnitude quicker than the other methods but the networks may need to be
re-trained for different acquisition protocols or imaged anatomical regions.
Conclusion: DNNs are recommended for accurate and robust IVIM model fitting to
DW-MRI data. Suitable software is available at (1)
Applying Winnow to Context-Sensitive Spelling Correction
Multiplicative weight-updating algorithms such as Winnow have been studied
extensively in the COLT literature, but only recently have people started to
use them in applications. In this paper, we apply a Winnow-based algorithm to a
task in natural language: context-sensitive spelling correction. This is the
task of fixing spelling errors that happen to result in valid words, such as
substituting {\it to\/} for {\it too}, {\it casual\/} for {\it causal}, and so
on. Previous approaches to this problem have been statistics-based; we compare
Winnow to one of the more successful such approaches, which uses Bayesian
classifiers. We find that: (1)~When the standard (heavily-pruned) set of
features is used to describe problem instances, Winnow performs comparably to
the Bayesian method; (2)~When the full (unpruned) set of features is used,
Winnow is able to exploit the new features and convincingly outperform Bayes;
and (3)~When a test set is encountered that is dissimilar to the training set,
Winnow is better than Bayes at adapting to the unfamiliar test set, using a
strategy we will present for combining learning on the training set with
unsupervised learning on the (noisy) test set.Comment: 9 page
Semi-Supervised Speech Emotion Recognition with Ladder Networks
Speech emotion recognition (SER) systems find applications in various fields
such as healthcare, education, and security and defense. A major drawback of
these systems is their lack of generalization across different conditions. This
problem can be solved by training models on large amounts of labeled data from
the target domain, which is expensive and time-consuming. Another approach is
to increase the generalization of the models. An effective way to achieve this
goal is by regularizing the models through multitask learning (MTL), where
auxiliary tasks are learned along with the primary task. These methods often
require the use of labeled data which is computationally expensive to collect
for emotion recognition (gender, speaker identity, age or other emotional
descriptors). This study proposes the use of ladder networks for emotion
recognition, which utilizes an unsupervised auxiliary task. The primary task is
a regression problem to predict emotional attributes. The auxiliary task is the
reconstruction of intermediate feature representations using a denoising
autoencoder. This auxiliary task does not require labels so it is possible to
train the framework in a semi-supervised fashion with abundant unlabeled data
from the target domain. This study shows that the proposed approach creates a
powerful framework for SER, achieving superior performance than fully
supervised single-task learning (STL) and MTL baselines. The approach is
implemented with several acoustic features, showing that ladder networks
generalize significantly better in cross-corpus settings. Compared to the STL
baselines, the proposed approach achieves relative gains in concordance
correlation coefficient (CCC) between 3.0% and 3.5% for within corpus
evaluations, and between 16.1% and 74.1% for cross corpus evaluations,
highlighting the power of the architecture
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