74 research outputs found
A simple technique for improving multi-class classification with neural networks
We present a novel method to perform multi-class pattern classification with
neural networks and test it on a challenging 3D hand gesture recognition
problem. Our method consists of a standard one-against-all (OAA)
classification, followed by another network layer classifying the resulting
class scores, possibly augmented by the original raw input vector. This allows
the network to disambiguate hard-to-separate classes as the distribution of
class scores carries considerable information as well, and is in fact often
used for assessing the confidence of a decision. We show that by this approach
we are able to significantly boost our results, overall as well as for
particular difficult cases, on the hard 10-class gesture classification task.Comment: European Symposium on artificial neural networks (ESANN), Jun 2015,
Bruges, Belgiu
A pragmatic approach to multi-class classification
We present a novel hierarchical approach to multi-class classification which
is generic in that it can be applied to different classification models (e.g.,
support vector machines, perceptrons), and makes no explicit assumptions about
the probabilistic structure of the problem as it is usually done in multi-class
classification. By adding a cascade of additional classifiers, each of which
receives the previous classifier's output in addition to regular input data,
the approach harnesses unused information that manifests itself in the form of,
e.g., correlations between predicted classes. Using multilayer perceptrons as a
classification model, we demonstrate the validity of this approach by testing
it on a complex ten-class 3D gesture recognition task.Comment: European Symposium on artificial neural networks (ESANN), Apr 2015,
Bruges, Belgium. 201
Efficient online bootstrapping of sensory representations
International audienceThis is a simulation-based contribution exploring a novel approach to the open-ended formation of multimodal representations in autonomous agents. In particular, we address the issue of transferring ("bootstrapping") feature selectivities between two modalities, from a previously learned or innate reference representation to a new induced representation. We demonstrate the potential of this algorithm by several experiments with synthetic inputs modeled after a robotics scenario where multimodal object representations are "bootstrapped" from a (reference) representation of object affordances. We focus on typical challenges in autonomous agents: absence of human supervision, changing environment statistics and limited computing power. We propose an autonomous and local neural learning algorithm termed PROPRE (projection-prediction) that updates induced representations based on predictability: competitive advantages are given to those feature-sensitive elements that are inferable from activities in the reference representation. PROPRE implements a bi-directional interaction of clustering ("projection") and inference ("prediction"), the key ingredient being an efficient online measure of predictability controlling learning in the projection step. We show that the proposed method is computationally efficient and stable, and that the multimodal transfer of feature selectivity is successful and robust under resource constraints. Furthermore, we successfully demonstrate robustness to noisy reference representations, non-stationary input statistics and uninformative inputs
A Framework for the Automated Parameterization of a Sensorless Bearing Fault Detection Pipeline
This study proposes a framework for the automated hyperparameter optimization
of a bearing fault detection pipeline for permanent magnet synchronous motors
(PMSMs) without the need of external sensors. A automated machine learning
(AutoML) pipeline search is performed by means of a genetic optimization to
reduce human induced bias due to inappropriate parameterizations. For this
purpose, a search space is defined, which includes general methods of signal
processing and manipulation as well as methods tailored to the respective task
and domain. The proposed framework is evaluated on the bearing fault detection
use case under real world conditions. Considerations on the generalization of
the deployed fault detection pipelines are also taken into account. Likewise,
attention was paid to experimental studies for evaluations of the robustness of
the fault detection pipeline to variations of the motors working condition
parameters between the training and test domain. The present work contributes
to the research of fault detection on rotating machinery in the following
terms: (1) Reduction of the human induced bias to the data science process,
while still considering expert and task related knowledge, ending in a generic
search approach (2) tackling the bearing fault detection task without the need
for external sensors (sensorless) (3) learning a domain robust fault detection
pipeline applicable to varying motor operating parameters without the need of
re-parameterizations or fine-tuning (4) investigations on working condition
discrepancies with an excessive degree to determine the pipeline limitations
regarding the abstraction of the motor parameters and the pipeline
hyperparametersComment: 8 pages, 4 figures, 5 tables, ieee conference paper template use
Co-training of context models for real-time object detection
International audienceWe describe a simple way to reduce the amount of required training data in context-based models of real- time object detection. We demonstrate the feasibility of our approach in a very challenging vehicle detection scenario comprising multiple weather, environment and light conditions such as rain, snow and darkness (night). The investigation is based on a real-time detection system effectively composed of two trainable components: an exhaustive multiscale object detector ("signal-driven detection"), as well as a module for generating object-specific visual attention ("context models") controlling the signal-driven detection process. Both parts of the system require a significant amount of ground-truth data which need to be generated by human annotation in a time-consuming and costly process. Assuming sufficient training examples for signal-based detection, we demonstrate that a co-training step can eliminate the need for separate ground-truth data to train context models. This is achieved by directly training context models with the results of signal-driven detection. We show that this process is feasible for different qualities of signal-driven detection, and maintains the performance gains from context models. As it is by now widely accepted that signal-driven object detection can be significantly improved by context models, our method allows to train strongly improved detection systems without additional labor, and above all, cost
A Study of Deep Learning for Network Traffic Data Forecasting
We present a study of deep learning applied to the domain of network traffic
data forecasting. This is a very important ingredient for network traffic
engineering, e.g., intelligent routing, which can optimize network performance,
especially in large networks. In a nutshell, we wish to predict, in advance,
the bit rate for a transmission, based on low-dimensional connection metadata
("flows") that is available whenever a communication is initiated. Our study
has several genuinely new points: First, it is performed on a large dataset
(~50 million flows), which requires a new training scheme that operates on
successive blocks of data since the whole dataset is too large for in-memory
processing. Additionally, we are the first to propose and perform a more
fine-grained prediction that distinguishes between low, medium and high bit
rates instead of just "mice" and "elephant" flows. Lastly, we apply
state-of-the-art visualization and clustering techniques to flow data and show
that visualizations are insightful despite the heterogeneous and non-metric
nature of the data. We developed a processing pipeline to handle the highly
non-trivial acquisition process and allow for proper data preprocessing to be
able to apply DNNs to network traffic data. We conduct DNN hyper-parameter
optimization as well as feature selection experiments, which clearly show that
fine-grained network traffic forecasting is feasible, and that domain-dependent
data enrichment and augmentation strategies can improve results. An outlook
about the fundamental challenges presented by network traffic analysis (high
data throughput, unbalanced and dynamic classes, changing statistics, outlier
detection) concludes the article.Comment: 16 pages, 12 figures, 28th International Conference on Artificial
Neural Networks (ICANN 2019
Incremental learning algorithms and applications
International audienceIncremental learning refers to learning from streaming data, which arrive over time, with limited memory resources and, ideally, without sacrificing model accuracy. This setting fits different application scenarios where lifelong learning is relevant, e.g. due to changing environments , and it offers an elegant scheme for big data processing by means of its sequential treatment. In this contribution, we formalise the concept of incremental learning, we discuss particular challenges which arise in this setting, and we give an overview about popular approaches, its theoretical foundations, and applications which emerged in the last years
Computational Advantages of Deep Prototype-Based Learning
International audienceWe present a deep prototype-based learning architecture which achieves a performance that is competitive to a conventional, shallow prototype-based model but at a fraction of the computational cost, especially w.r.t. memory requirements. As prototype-based classification and regression methods are typically plagued by the exploding number of prototypes necessary to solve complex problems, this is an important step towards efficient prototype-based classification and regression. We demonstrate these claims by benchmarking our deep prototype-based model on the well-known MNIST dataset
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