Unsupervised learning of finite full covariance multivariate generalized Gaussian mixture models for human activity recognition

2019 ◽  
Vol 78 (13) ◽  
pp. 18669-18691 ◽  
Author(s):  
Fatma Najar ◽  
Sami Bourouis ◽  
Nizar Bouguila ◽  
Safya Belghith
Keyword(s):  
Unsupervised Learning ◽  
Mixture Models ◽  
Activity Recognition ◽  
Human Activity ◽  
Gaussian Mixture Models ◽  
Gaussian Mixture ◽  
Human Activity Recognition

scholarly journals Collaborative Graph Convolutional Networks: Unsupervised Learning Meets Semi-Supervised Learning

2020 ◽  
Vol 34 (04) ◽  
pp. 4215-4222
Author(s):  
Binyuan Hui ◽  
Pengfei Zhu ◽  
Qinghua Hu
Keyword(s):  
Unsupervised Learning ◽  
Supervised Learning ◽  
Mixture Models ◽  
Gaussian Mixture Models ◽  
Graph Clustering ◽  
Gaussian Mixture ◽  
Complex Data ◽  
Convolutional Networks ◽  
Attributed Graph ◽  
Node Classification

Graph convolutional networks (GCN) have achieved promising performance in attributed graph clustering and semi-supervised node classification because it is capable of modeling complex graphical structure, and jointly learning both features and relations of nodes. Inspired by the success of unsupervised learning in the training of deep models, we wonder whether graph-based unsupervised learning can collaboratively boost the performance of semi-supervised learning. In this paper, we propose a multi-task graph learning model, called collaborative graph convolutional networks (CGCN). CGCN is composed of an attributed graph clustering network and a semi-supervised node classification network. As Gaussian mixture models can effectively discover the inherent complex data distributions, a new end to end attributed graph clustering network is designed by combining variational graph auto-encoder with Gaussian mixture models (GMM-VGAE) rather than the classic k-means. If the pseudo-label of an unlabeled sample assigned by GMM-VGAE is consistent with the prediction of the semi-supervised GCN, it is selected to further boost the performance of semi-supervised learning with the help of the pseudo-labels. Extensive experiments on benchmark graph datasets validate the superiority of our proposed GMM-VGAE compared with the state-of-the-art attributed graph clustering networks. The performance of node classification is greatly improved by our proposed CGCN, which verifies graph-based unsupervised learning can be well exploited to enhance the performance of semi-supervised learning.

scholarly journals Combining Supervised and Unsupervised Learning Algorithms for Human Activity Recognition

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6309
Author(s):  
Elena-Alexandra Budisteanu ◽  
Irina Georgiana Mocanu
Keyword(s):  
Unsupervised Learning ◽  
Activity Recognition ◽  
Human Activity ◽  
Data Augmentation ◽  
Learning Algorithms ◽  
Human Activity Recognition ◽  
Convolutional Networks ◽  
Supervised And Unsupervised Learning ◽  
Novel Approach ◽  
Unsupervised Deep Learning

Human activity recognition is an extensively researched topic in the last decade. Recent methods employ supervised and unsupervised deep learning techniques in which spatial and temporal dependency is modeled. This paper proposes a novel approach for human activity recognition using skeleton data. The method combines supervised and unsupervised learning algorithms in order to provide qualitative results and performance in real time. The proposed method involves a two-stage framework: the first stage applies an unsupervised clustering technique to group up activities based on their similarity, while the second stage classifies data assigned to each group using graph convolutional networks. Different clustering techniques and data augmentation strategies are explored for improving the training process. The results were compared against the state of the art methods and the proposed model achieved 90.22% Top-1 accuracy performance for NTU-RGB+D dataset (the performance was increased by approximately 9% compared with the baseline graph convolutional method). Moreover, inference time and total number of parameters stay within the same magnitude order. Extending the initial set of activities with additional classes is fast and robust, since there is no required retraining of the entire architecture but only to retrain the cluster to which the activity is assigned.

scholarly journals Human Activity Recognition Using Gaussian Mixture Hidden Conditional Random Fields

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Muhammad Hameed Siddiqi ◽  
Madallah Alruwaili ◽  
Amjad Ali ◽  
Saad Alanazi ◽  
Furkh Zeshan
Keyword(s):  
Activity Recognition ◽  
Human Activity ◽  
Random Fields ◽  
Classification Accuracy ◽  
Conditional Random Fields ◽  
Gaussian Mixture ◽  
Human Activity Recognition ◽  
Substantial Improvement ◽  
Learning Method ◽  
Proposed Model

In healthcare, the analysis of patients’ activities is one of the important factors that offer adequate information to provide better services for managing their illnesses well. Most of the human activity recognition (HAR) systems are completely reliant on recognition module/stage. The inspiration behind the recognition stage is the lack of enhancement in the learning method. In this study, we have proposed the usage of the hidden conditional random fields (HCRFs) for the human activity recognition problem. Moreover, we contend that the existing HCRF model is inadequate by independence assumptions, which may reduce classification accuracy. Therefore, we utilized a new algorithm to relax the assumption, allowing our model to use full-covariance distribution. Also, in this work, we proved that computation wise our method has very much lower complexity against the existing methods. For the experiments, we used four publicly available standard datasets to show the performance. We utilized a 10-fold cross-validation scheme to train, assess, and compare the proposed model with the conditional learning method, hidden Markov model (HMM), and existing HCRF model which can only use diagonal-covariance Gaussian distributions. From the experiments, it is obvious that the proposed model showed a substantial improvement with p value ≤0.2 regarding the classification accuracy.

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