Sensor-based human activity recognition (HAR) plays a fundamental role in various mobile application scenarios, but the model performance of HAR heavily relies on the richness of the dataset and the completeness of data annotation. To address the shortage of comprehensive activity types in collected datasets, we adopt the domain adaptation technique with a graph neural network-based approach by incorporating an adaptive learning mechanism to enhance the action recognition model’s generalization ability, especially when faced with limited sample sizes. To evaluate the effectiveness of our proposed approach, we conducted experiments using three well-known datasets: MHealth, PAMAP2, and TNDA. The experimental results demonstrate the efficacy of our approach in sensor-based HAR tasks, achieving impressive average accuracies of 98.88%, 98.58%, and 97.78% based on the respective datasets. Furthermore, we conducted transfer learning experiments to address the domain adaptation problem. These experiments revealed that our proposed model exhibits exceptional transferability and distinguishing ability, even in scenarios with limited available samples. Thus, our approach offers a practical and viable solution for sensor-based HAR tasks.

This work presents a topological nonlinear analysis approach for dynamical system measurements, frequently appearing in sensor-based inference tasks in human physical activity analysis. Traditional approaches to dynamical modeling included linear and nonlinear methods with specific representational abilities and some drawbacks. A novel approach we investigate is using topological descriptors of the shape of the dynamical attractor to represent the nature of dynamics. The proposed framework has three essential advantages compared to previous approaches: 1) with nonlinear phase space reconstruction, the dynamics descriptor is derived from the observation time series without any statistical assumption; 2) with the topological data analysis technique, the phase space topological properties are described in an intrinsic multiresolution analytical way, which brings novel information compared to traditional phase-space modeling techniques; 3) with different types of measurement sensing signals, the proposed approach shows stability in activities state inference. We illustrate our idea with the physical activity recognition tasks with wearable sensors, where the topological characteristics of reconstructed phase state space show strong representational ability for activity type inference.

In the framework of intelligent aided language learning, a real-time data-driven 3D visual pronunciation system of Chinese IPA is proposed. First, a high quality articulatory speech corpus including speech and 3D articulatory data of lips, tongue and jaw movements is collected through Electro-Magnetic Articulograph; second, the 3D articulatory modeling including shape design and motion synthesis is conducted. The articulatory shape is obtained by designing a precise 3D facial model including internal and external articulators. The articulatory motion synthesis is obtained combining parameterized model and anatomical model. The system can thus illustrate the slight differences among phonemes by synthesizing both internal and external articulatory movements. The perceptual evaluation shows the suitability of the system for instructing language learners to articulate.