Leveraging electrocardiogram (ECG) signals for emotion recognition represents a core challenge in affective computing, particularly in achieving robustness across diverse demographic groups (such as older adults with mild cognitive impairment). This challenge is rooted in three key issues: the complex multi-scale nature of ECG signals, high inter-individual physiological variability, and the need for computationally efficient temporal modeling for IoT applications. To address these issues systematically, this study proposes HCMNet, a novel, physiologically-inspired hybrid Convolutional-Mamba network. HCMNet’s architecture is problem-driven: a hierarchical scale-aware convolutional module captures multi-scale features analogous to HRV analysis; an innovative Non-Local Channel Convolutional Attention (NLCCA) mechanism mitigates inter-individual variability by learning to reshape the feature space; and a Mamba2-based Bidirectional State-Space Model (BiSSM) efficiently models temporal dynamics with linear complexity. Additionally, we validated the model on a self-built Wearable ECG emotion dataset comprising healthy elderly individuals and patients with mild cognitive impairment (MCI), as well as on public datasets WESAD and DREAMER. Experimental results demonstrate that our proposed HCMNet, through its synergistic hybrid architecture, effectively extracts robust emotional features. It not only achieves state-of-the-art performance on public benchmarks but also exhibits strong robustness for special populations. Furthermore, our in-depth adaptation analysis reveals that while a “one-model-fits-all” approach is infeasible for unseen subjects, HCMNet excels as a robust transferable base model that can be rapidly personalized, offering a practical paradigm for accurate and adaptable emotion recognition in real-world IoT settings. The source code is available at https://github.com/INSOCE/HCMNet.

In recent years, the demand for smart healthcare solutions have heightened the need for accuracy, reliability, and comfort in bedside ECG recording and analysis. This study presents a bedside non-direct contact ECG recording system based on capacitive coupling electrocardiography (cECG) and verifies its performance in accurately capturing Heart Rate Variability (HRV) during the night. Firstly, cECG collects ECG data through clothing, avoiding skin irritation from conventional wet electrodes. Secondly, leveraging the unique characteristics of cECG signals, a deep learning framework assesses the quality of cECG, filtering noise and identifying off-bed information, enhancing HRV analysis precision. Subsequently, the system was employed to recording sleep data from 6 subjects overnight, with our proposed algorithm utilized for signal quality assessment (SQA) and HRV analysis. Finally, HRV features were compared with synchronously collected wet electrode ECG signals, encompassing time domain features, frequency domain features, and nonlinear features, totaling 13 HRV features. Experimental findings demonstrate that for the SQA task, the model achieved a classification accuracy of 94.7%, with a Recall of 0.941, Precision of 0.940, F1 score of 0.941, and Cohen's Kappa of 0.927. The accuracy of on/off-bed monitoring reached 99.79%. Additionally, HRV features showed a strong correlation with the reference ECG. In the time-domain metrics, the largest mean absolute percentage error (MAPE) is for PNN50, with a value of 8.148%. In the frequency-domain features, the largest MAPE is for HF, with a value of 13.253%. For nonlinear features, the largest MAPE is for SD1, with a value of 5.182%. Generally, the system exhibited a reliable solution for cECG recording, on/off-bed status detection, and bedside HRV analysis.

The combination of wearable sensors and competitive sports provides quantitative information for scientific training, effectively assisting athletes in improving their athletic performance. This study presents a technical framework for athletic sports assessment in competitive swimming based on body-area sensor networks. In our approach, wearable inertial sensor nodes are placed on specific body parts of the athletes to capture motion data during different competitive swimming strokes. Multiwearable inertial sensor nodes are worn on specific body parts of athletes for real-time monitoring motion data during training sessions. A motion intensity detection-based error-state-Kalman-filter algorithm is proposed for multisensor data fusion. Additionally, through kinematic statistical analysis, the characteristics of joint motion during training are clearly explained. Furthermore, a deep learning network that fuses sensor time series and human skeleton graphs is proposed for different stroke phase segmentation, enabling quantitative measurement of motion phases, and several baseline classifiers are chosen for comparison to validate the robustness of our phase segmentation method. We also investigate the sensor combination selection issue during the phase segmentation process to determine the optimal sensor configuration. Our approach provides a scientific solution for the integration of wearable sensors and competitive sports, contributing to the high-quality development of the next generation of smart sports.

SpeechDepressionDetection (SDD) has garnered attention from researchers due to its low cost and convenience. However, current algorithms lack methods for extracting interpretable acoustic features based on clinical manifestations. In addition, effectively fusing these features to overcome individual heterogeneity remains a challenge. This study proposes a decoupled multi-perspective fusion (DMPF) model. The model extracts five key features of voiceprint, emotion, pause, energy, and tremor based on the multi-perspective clinical manifestations. These features are then decoupled into common and private features, which fused through graph attention network to obtain the comprehensive depression representation. Notably, this study has collected a depression speech dataset, which includes standardized and comprehensive tasks along with diagnostic labels provided by psychologists. Extensive subject-independent experiments were conducted on the DAIC-WOZ, MODMA and MPSC datasets. The voiceprint features can automatically cluster the depressed and non-depressed populations. Furthermore, DMPF can effectively fuse common and private features from different perspectives, achieving AUC of 84.20%, 85.34%, 86.13% on three datasets. The results illustrate the interpretability of multi-perspective features and demonstrate that the combination of speech manifestations can enhance the detection ability, which can provide a multi-perspective observational tool for physicians and clinical practice.

Complexity measurement, essential in diverse fields like finance, biomedicine, climate science, and network traffic, demands real-time computation to mitigate risks and losses. Sample Entropy (SampEn) is an efficacious metric which quantifies the complexity by assessing the similarities among microscale patterns within the time-series data. Unfortunately, the conventional implementation of SampEn is computationally demanding, posing challenges for its application in real-time analysis, particularly for long time series. Field Programmable Gate Arrays (FPGAs) offer a promising solution due to their fast processing and energy efficiency, which can be customized to perform specific signal processing tasks directly in hardware. The presented work focuses on accelerating SampEn analysis on FPGAs for efficient time-series complexity analysis. A refined, fast, Lightweight SampEn architecture (LW SampEn) on FPGA, which is optimized to use sorted sequences to reduce computational complexity, is accelerated for FPGAs. Various sorting algorithms on FPGAs are assessed, and novel dynamic loop strategies and micro-architectures are proposed to tackle SampEn's undetermined search boundaries. Multi-source biomedical signals are used to profile the above design and select a proper architecture, underscoring the importance of customizing FPGA design for specific applications. Our optimized architecture achieves a 7x to 560x speedup over standard baseline architecture, enabling real-time processing of time-sensitive data.

Automated sleep staging is crucial for assessing sleep quality and diagnosing sleep-related diseases. Single-channel EEG has attracted significant attention due to its portability and accessibility. Most existing automated sleep staging methods often emphasize temporal information and neglect spectral information, the relationship between sleep stage contextual features, and transition rules between sleep stages. To overcome these obstacles, this paper proposes an attention-based two stage temporal-spectral fusion model (BiTS-SleepNet). The BiTS-SleepNet stage 1 network consists of a dual-stream temporal-spectral feature extractor branch and a temporal-spectral feature fusion module based on the cross-attention mechanism. These blocks are designed to autonomously extract and integrate the temporal and spectral features of EEG signals, leveraging temporal-spectral fusion information to discriminate between different sleep stages. The BiTS-SleepNet stage 2 network includes a feature context learning module (FCLM) based on Bi-GRU and a transition rules learning module (TRLM) based on the Conditional Random Field (CRF). The FCLM optimizes preliminary sleep stage results from the stage 1 network by learning dependencies between features of multiple adjacent stages. The TRLM additionally employs transition rules to optimize overall outcomes. We evaluated the BiTS-SleepNet on three public datasets: Sleep-EDF-20, Sleep-EDF-78, and SHHS, achieving accuracies of 88.50%, 85.09%, and 87.01%, respectively. The experimental results demonstrate that BiTS-SleepNet achieves competitive performance in comparison to recently published methods. This highlights its promise for practical applications.

Datasets often include noisy labels, but learning from them is difficult. Since mislabeled examples usually have larger loss values in training, the small-loss trick is regarded as a standard metric to identify the clean example from the training set for better performance. Nonetheless, this proposal ignores that some clean but hard-to-learn examples also generate large losses. They could be misidentified by this criterion. In this paper, we propose a new metric called the Integrated Area Margin (IAM), which is superior to the traditional small-loss trick, particularly in recognizing the clean but hard-to-learn examples. According to the IAM, we further offer the Hyperspherical Margin Weighting (HMW) approach. It is a new sample weighting strategy that restructures the importance of each example. It should be highlighted that our approach is universal and can strengthen various methods in this field. Experiments on both benchmark and real-world datasets indicate that our HMW outperforms many state-of-the-art approaches in learning with noisy label tasks. Codes are available at https://github.com/Zhangshuojackpot/HMW.

Noisy labels are often encountered in datasets, but learning with them is challenging. Although natural discrepancies between clean and mislabeled samples in a noisy category exist, most techniques in this field still gather them indiscriminately, which leads to their performances being partially robust. In this paper, we reveal both empirically and theoretically that the learning robustness can be improved by assuming deep features with the same labels follow a student distribution, resulting in a more intuitive method called student loss. By embedding the student distribution and exploiting the sharpness of its curve, our method is naturally data-selective and can offer extra strength to resist mislabeled samples. This ability makes clean samples aggregate tightly in the center, while mislabeled samples scatter, even if they share the same label. Additionally, we employ the metric learning strategy and develop a large-margin student (LT) loss for better capability. It should be noted that our approach is the first work that adopts the prior probability assumption in feature representation to decrease the contributions of mislabeled samples. This strategy can enhance various losses to join the student loss family, even if they have been robust losses. Experiments demonstrate that our approach is more effective in inaccurate supervision. Enhanced LT losses significantly outperform various state-of-the-art methods in most cases. Even huge improvements of over 50% can be obtained under some conditions.

Automatic emotion recognition based on multichannel Electroencephalography (EEG) holds great potential in advancing human-computer interaction. However, several significant challenges persist in existing research on algorithmic emotion recognition. These challenges include the need for a robust model to effectively learn discriminative node attributes over long paths, the exploration of ambiguous topological information in EEG channels and effective frequency bands, and the mapping between intrinsic data qualities and provided labels. To address these challenges, this study introduces the distribution-based uncertainty method to represent spatial dependencies and temporal-spectral relativeness in EEG signals based on Graph Convolutional Network (GCN) architecture that adaptively assigns weights to functional aggregate node features, enabling effective long-path capturing while mitigating over-smoothing phenomena. Moreover, the graph mixup technique is employed to enhance latent connected edges and mitigate noisy label issues. Furthermore, we integrate the uncertainty learning method with deep GCN weights in a one-way learning fashion, termed Connectivity Uncertainty GCN (CU-GCN). We evaluate our approach on two widely used datasets, namely SEED and SEEDIV, for emotion recognition tasks. The experimental results demonstrate the superiority of our methodology over previous methods, yielding positive and significant improvements. Ablation studies confirm the substantial contributions of each component to the overall performance.

The value of Electrocardiogram (ECG) monitoring in early cardiovascular disease (CVD) detection is undeniable, especially with the aid of intelligent wearable devices. Despite this, the requirement for expert interpretation significantly limits public accessibility, underscoring the need for advanced diagnosis algorithms. Deep learning-based methods represent a leap beyond traditional rule-based algorithms, but they are not without challenges such as small databases, inefficient use of local and global ECG information, high memory requirements for deploying multiple models, and the absence of task-to-task knowledge transfer. In response to these challenges, we propose a multi-resolution model adept at integrating local morphological characteristics and global rhythm patterns seamlessly. We also introduce an innovative ECG continual learning (ECG-CL) approach based on parameter isolation, designed to enhance data usage effectiveness and facilitate inter-task knowledge transfer. Our experiments, conducted on four publicly available databases, provide evidence of our proposed continual learning method's ability to perform incremental learning across domains, classes, and tasks. The outcome showcases our method's capability in extracting pertinent morphological and rhythmic features from ECG segmentation, resulting in a substantial enhancement of classification accuracy. This research not only confirms the potential for developing comprehensive ECG interpretation algorithms based on single-lead ECGs but also fosters progress in intelligent wearable applications. By leveraging advanced diagnosis algorithms, we aspire to increase the accessibility of ECG monitoring, thereby contributing to early CVD detection and ultimately improving healthcare outcomes.

Precise segmentation is a vital first step to analyze semantic information of cardiac cycle and capture anomaly with cardiovascular signals. However, in the field of deep semantic segmentation, inference is often unilaterally confounded by the individual attribute of data. Towards cardiovascular signals, quasi-periodicity is the essential characteristic to be learned, regarded as the synthesize of the attributes of morphology ($A_{m}$) and rhythm ($A_{r}$). Our key insight is to suppress the over-dependence on$A_{m}$or$A_{r}$while the generation process of deep representations. To address this issue, we establish a structural causal model as the foundation to customize the intervention approaches on$A_{m}$and$A_{r}$, respectively. In this article, we propose contrastive causal intervention (CCI) to form a novel training paradigm under a frame-level contrastive framework. The intervention can eliminate the implicit statistical bias brought by the single attribute and lead to more objective representations. We conduct comprehensive experiments with the controlled condition for QRS location and heart sound segmentation. The final results indicate that our approach can evidently improve the performance by up to 0.41% for QRS location and 2.73% for heart sound segmentation. The efficiency of the proposed method is generalized to multiple databases and noisy signals.

Sample Entropy (SampEn) is an information en-tropy algorithm widely used for complexity analysis and chaos estimation in many applications. In particular, SampEn measures complexity of time series by the conditional probability of the inner pattern. Unfortunately, the straightforward implementation of SampEn is quadratic time complexity, restricting its real-time analysis ability for health applications and long-term data analysis. Although researchers have proposed fast versions of SampEn to avoid unnecessary comparisons, they have not been accelerated yet due to their performance bottleneck in the complex similarity pair process. In this paper, we evaluate fast SampEn algorithms by employing multi-source biomedical signals on an Field-Programmable Gate Arrays (FPGA). Since fast SampEn algorithms based of a pre-sorting stage promise to outperform other SampEn algorithms, Lightweight SampEn based on Merge Sort is here implemented and optimized. Dif-ferent type of optimizations, that can be generalized for similar Lightweight-based SampEn algorithms, are used to reduce the overall latency while the data throughput is increased. A load balancing strategy for multi similarity pair modules is also proposed to solve the unbalancing loads, a bottleneck when increasing the execution parallelism of this type of algorithms. As a result, the proposed SampEn architecture runs 10 times faster than the fastest SampEn implementation on a modern CPU.

The analysis of facial expression is a very complex and challenging problem. Most researches for automated Facial Expression Recognition (FER) are mainly based on deep learning networks, rarely considering data imbalance. This paper commits to addressing the long-tail distribution problems among large-scale datasets in wild. Inspired by the continual learning method, we reconstruct multi-subsets first by randomly selecting from head classes and up-sampling tail classes. A pre-trained backbone is then introduced to learn general weights in a repeatedly train-prune fashion. Hereafter, our approach creatively trains a new classifier based on union parameters previously preserved and achieves an outperformance without extra parameters added in, using the gradual-prune technique. The results show that the independent training of classifiers has been a contributing factor. We successfully conduct this experiment with several classic networks, prove its effectiveness in training a deep network on imbalanced dataset. In the face of the poor performance in current FER, we find that domain knowledge is somehow affecting the accuracy of recognition by further exploring the obstacles from the image itself.Code available at https://github.com/Epicghx/FER

Recently, development of wearable and Internet of Things (IoT) technologies enables the real-time and continuous individual electrocardiogram (ECG) monitoring. In this paper, we develop a novel IoT-based wearable 12-lead ECG SmartVest system for early detection of cardiovascular diseases, which consists of four typical IoT components: 1) sensing layer using textile dry ECG electrode; 2) network layer utilizing Bluetooth, WiFi, etc.; 3) cloud saving and calculation platform and server; and 4) application layer for signal analysis and decision making. We focus on addressing the challenge of real-time signal quality assessment (SQA) and lightweight QRS detection for wearable ECG application. First, a combination method of multiple signal quality indices and machine learning is proposed for classifying 10-s single-channel ECG segments as acceptable and unacceptable. Then a lightweight QRS detector is developed for accurate location of QRS complexes. The results show that the proposed SQA method can efficiently deal with tradeoff between accepting good (97.9%) and rejecting poor (96.4%) quality ECGs, ensuring that only a low percentage of recorded ECGs are discarded. The proposed lightweight QRS detector achieves a${F_{1}}$score higher than 99.5% for processing clean ECGs. Meanwhile, it reports significantly higher${F_{1}}$scores than two existing QRS detectors for processing noisy ECGs. In addition, it also has a fine computation efficiency. This paper demonstrates that the developed IoT-driven ECG SmartVest system can be applied for widely monitoring the population during daily life and has a promising application future.

Speech is easily affected by different background noise in real environment to reduce the speech intelligibility, in particular, for hearing impaired listeners. In order to improve the above issue, several hearing aids have been developed to enhance the speech signal in noisy environment. Most of current hearing aids were designed to enhance the component of speech and suppress the component of noise. However, it is difficult to separate other speech sources. Adaptive signal enhancement with the beamforming technique might improve the above issue. However, how to distinguish the location of the desired speaker effectively is still a difficult challenge for adaptive beamforming method. A novel concept of hearing aid was proposed in this study. Different from the beamforming-based hearing aids, which use the crosscorrelation-coefficient method to estimate time difference of arrival (TDOA), an image recognition technology was used to estimate the location of the desired speaker to obtain the more precise TDOA. An adaptive signal enhancement was also used to enhance the noisy speech sound. From the experimental results, the proposed system could provide a smaller absolute error of TDOA less than 1.25 × 10-4ms, and a clear speech sound from the target speaker who the user wants to listen to.