222 research outputs found
A Semisupervised Recurrent Convolutional Attention Model for Human Activity Recognition.
Recent years have witnessed the success of deep learning methods in human activity recognition (HAR). The longstanding shortage of labeled activity data inherently calls for a plethora of semisupervised learning methods, and one of the most challenging and common issues with semisupervised learning is the imbalanced distribution of labeled data over classes. Although the problem has long existed in broad real-world HAR applications, it is rarely explored in the literature. In this paper, we propose a semisupervised deep model for imbalanced activity recognition from multimodal wearable sensory data. We aim to address not only the challenges of multimodal sensor data (e.g., interperson variability and interclass similarity) but also the limited labeled data and class-imbalance issues simultaneously. In particular, we propose a pattern-balanced semisupervised framework to extract and preserve diverse latent patterns of activities. Furthermore, we exploit the independence of multi-modalities of sensory data and attentively identify salient regions that are indicative of human activities from inputs by our recurrent convolutional attention networks. Our experimental results demonstrate that the proposed model achieves a competitive performance compared to a multitude of state-of-the-art methods, both semisupervised and supervised ones, with 10% labeled training data. The results also show the robustness of our method over imbalanced, small training data sets
Investigating Deep Neural Network Architecture and Feature Extraction Designs for Sensor-based Human Activity Recognition
The extensive ubiquitous availability of sensors in smart devices and the
Internet of Things (IoT) has opened up the possibilities for implementing
sensor-based activity recognition. As opposed to traditional sensor time-series
processing and hand-engineered feature extraction, in light of deep learning's
proven effectiveness across various domains, numerous deep methods have been
explored to tackle the challenges in activity recognition, outperforming the
traditional signal processing and traditional machine learning approaches. In
this work, by performing extensive experimental studies on two human activity
recognition datasets, we investigate the performance of common deep learning
and machine learning approaches as well as different training mechanisms (such
as contrastive learning), and various feature representations extracted from
the sensor time-series data and measure their effectiveness for the human
activity recognition task.Comment: Seventh International Conference on Internet of Things and
Applications (IoT 2023
The Domain Mismatch Problem in the Broadcast Speaker Attribution Task
The demand of high-quality metadata for the available multimedia content requires the development of new techniques able to correctly identify more and more information, including the speaker information. The task known as speaker attribution aims at identifying all or part of the speakers in the audio under analysis. In this work, we carry out a study of the speaker attribution problem in the broadcast domain. Through our experiments, we illustrate the positive impact of diarization on the final performance. Additionally, we show the influence of the variability present in broadcast data, depicting the broadcast domain as a collection of subdomains with particular characteristics. Taking these two factors into account, we also propose alternative approximations robust against domain mismatch. These approximations include a semisupervised alternative as well as a totally unsupervised new hybrid solution fusing diarization and speaker assignment. Thanks to these two approximations, our performance is boosted around a relative 50%. The analysis has been carried out using the corpus for the Albayzín 2020 challenge, a diarization and speaker attribution evaluation working with broadcast data. These data, provided by Radio Televisión Española (RTVE), the Spanish public Radio and TV Corporation, include multiple shows and genres to analyze the impact of new speech technologies in real-world scenarios
A state-of-the-art of physics-informed neural networks in engineering
Técnicas de machine learning vêm ganhando cada vez mais espaço no cenário industrial no intuito de converter o crescente fluxo de informação (data) em melhorias de processos. Entre tais técnicas, as redes neuronais se destacam devido à sua capacidade de aproximador universal de funções, cuja performance pode ser enriquecida ao se fornecer conhecimentos físicos prévios: tem-se, então, o desenvolvimento das
Physics-informed neural networks (PINN). Nesse contexto e observando-se um “gap” na produção de trabalhos relacionados ao tema e da difusão dessa temática na grade de formação dos cursos da Escola de Química, esse trabalho se propõe a realizar um estado da arte da técnica mencionada. Observou-se interesse particular das PINN para aplicações em mecânica dos fluidos e transferência de calor. Ademais, as PINN
se mostram ferramentas importantes tanto para a resolução de problemas ditos “diretos” quanto “indiretos”. Por fim, através de exemplos práticos, constatou-se a capacidade de se aproximar funções de interesse particular na indústria química usando-se redes neurais sem nenhuma informação física do problema (obtenção do fator de atrito) e utilizando-se a equação diferencial que descreve o problema (resolução da equação de difusão em 1D)
A Comprehensive Survey of Deep Learning in Remote Sensing: Theories, Tools and Challenges for the Community
In recent years, deep learning (DL), a re-branding of neural networks (NNs),
has risen to the top in numerous areas, namely computer vision (CV), speech
recognition, natural language processing, etc. Whereas remote sensing (RS)
possesses a number of unique challenges, primarily related to sensors and
applications, inevitably RS draws from many of the same theories as CV; e.g.,
statistics, fusion, and machine learning, to name a few. This means that the RS
community should be aware of, if not at the leading edge of, of advancements
like DL. Herein, we provide the most comprehensive survey of state-of-the-art
RS DL research. We also review recent new developments in the DL field that can
be used in DL for RS. Namely, we focus on theories, tools and challenges for
the RS community. Specifically, we focus on unsolved challenges and
opportunities as it relates to (i) inadequate data sets, (ii)
human-understandable solutions for modelling physical phenomena, (iii) Big
Data, (iv) non-traditional heterogeneous data sources, (v) DL architectures and
learning algorithms for spectral, spatial and temporal data, (vi) transfer
learning, (vii) an improved theoretical understanding of DL systems, (viii)
high barriers to entry, and (ix) training and optimizing the DL.Comment: 64 pages, 411 references. To appear in Journal of Applied Remote
Sensin
Label-efficient Time Series Representation Learning: A Review
The scarcity of labeled data is one of the main challenges of applying deep
learning models on time series data in the real world. Therefore, several
approaches, e.g., transfer learning, self-supervised learning, and
semi-supervised learning, have been recently developed to promote the learning
capability of deep learning models from the limited time series labels. In this
survey, for the first time, we provide a novel taxonomy to categorize existing
approaches that address the scarcity of labeled data problem in time series
data based on their dependency on external data sources. Moreover, we present a
review of the recent advances in each approach and conclude the limitations of
the current works and provide future directions that could yield better
progress in the field.Comment: Under Revie
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