Recent advances in underwater sonar detection have highlighted the challenges of acquiring real-world sonar data due to experimental costs and environmental constraints. While deep learning-based methods have shown promise in sonar synthesis, existing approaches often lack fidelity in waveform generation. This manuscript proposes Multi-Band HiFi-GAN, a high-fidelity synthesis method that incorporates a multi-band processing module based on a Pseudo-QMF bank for spectrally-efficient sub-band decomposition, and Multi-Band STFT Discriminator (MBSD) that jointly models time-frequency structures and mitigates aliasing artifacts. Additionally, we design a multi-resolution STFT loss to enhance convergence. Evaluated on DeepShip dataset using Fréchet Audio Distance (FAD), our method demonstrates superior performance, achieving a lower FAD score than existing approaches. Augmenting real training data with synthesized samples improves target classification accuracy to 96.94% at a 100% mixing ratio. The work provides a practical data augmentation solution for underwater acoustic systems, improving synthesis fidelity.

Machine learning, particularly deep learning, typically achieves high facial emotion image recognition accuracy benefiting from multiple labeled data. However, the datasets usually contain insufficient labeled samples and numerous unlabeled data since human labeling is a costly endeavor. For semi-supervised learning of these datasets, self-training procedure solely based on the visual features of images fails to comprehensively understand the intricate high-level semantic features. Since EEG signals contain not only visual information related to the visual stimulus but also emotional information related to brain activity, they are highly suitable as supervisory signals for labeling unlabeled facial emotion images. In this study, we specifically employ EEG signals evoked by visual image stimuli in conjunction with EEGNet3D to learn a discriminative EEG class representation manifold of brain activity. The one-hot class label is replaced with the EEG class representation as the supervisory to train the base model. Then, better pseudo-labeling is achieved using the base model in the EEG class representation manifold. Based on pseudo-labeling results, the utilization of unlabeled data is further improved. Interestingly, our findings reveal that when utilizing EEG class representations as supervisory information for the base model, the base model demonstrates a learning pattern that involves focusing more on the eye area when making judgments about emotions. This behavior closely resembles how the human brain decodes emotions. Experiments show that the performance of the proposed method can be effectively enhanced by combining labeled and pseudo-labeled images. Further experiments demonstrate that our method exhibits strong generalization abilities when applied to new image datasets and other visual networks.

Biometric recognition using visually evoked potentials (VEPs), a type of neural response to visual stimuli recorded via electroencephalography (EEG), has shown great promise. However, the non-stationary nature of EEG signals poses a major challenge in cross-session scenarios, where data collected on different days often leads to performance degradation. To address this, we propose the Discriminative Robust Feature Network (DRFNet) to enhance the robustness and inter-subject discriminability of identity representations across sessions. DRFNet incorporates two key components: (1) A log-power transformation that amplifies inter-individual differences by capturing non-linear energy patterns from VEP features via signal squaring and logarithmic scaling; and (2) A hierarchical normalization strategy with adaptive attention to balance discriminative identity cues with inter-session invariance by stabilizing feature distributions across multiple levels (feature map, batch, and sample). On two public multi-session SSVEP datasets (Dataset A: 30 subjects, 6 s trials; Dataset B: 54 subjects, 4 s trials), our model outperformed state-of-the-art methods, achieving identification accuracies of 92.92% and 86.30%, and equal error rates of 3.92% and 4.09%, respectively. Further analysis demonstrates that filter bank processing and a reduced set of parietal-occipital electrodes can provide more discriminative features while offering a practical path toward system lightweighting.

Domainadaptation has proven effective for suppressing the inter-subject variability problem in cross-subject EEG classification tasks in which labeled data is available for source subjects while only unlabeled data is provided for target subjects. Existing domain adaptation methods typically reduced the distribution discrepancy between source and target domains by directly utilizing source domain samples or features. To safeguard the privacy of source domain data, we propose to construct a Proxy Domain by simultaneously considering the prediction Consistency and Confidence (PDCC) of locally trained source models on target EEG samples, serving as the substitute to the source domain. The framework commences with the augmentation and alignment of the source domain data to enhance feature generalizability, after which source models are trained independently on each source subject's data in a decentralized manner. Knowledge transfer from source to target domains is achieved exclusively through accessing to the source domain model, enabling the PDCC-based proxy domain construction that encapsulates the source knowledge. Finally, domain adaptation is performed using the proxy domain and target domain. As a result, PDCC eliminates the need to access source domain data while effectively leveraging source knowledge. Experimental results on four benchmark EEG datasets demonstrate that PDCC consistently outperforms eleven existing methods, including several advanced transfer learning and source-free methods. Especially, the effectiveness of the proxy domain is extensively investigated.

In real-world scenarios, multimodal sentiment analysis faces significant challenges, particularly in cross-scenario generalization. Existing works fail to effectively deal with the variability in evaluation frameworks and modality combinations, which results in poor transfer performance across different application contexts. In this article, the cognition-driven adaptive semantic decoding framework (CASDF) is proposed to realize an evaluation system and modality-independent multimodal sentiment analysis. Specifically, the adaptive modality association module is proposed to construct the adaptive modality mapping space, which allows us to dynamically adapt to arbitrary modality combinations. This indeed breaks through the limitation of the modality number and effectively deals with the modality gap. Furthermore, similar to the human hierarchical cognition (“perception-concept-decision”), the evaluation system progressive alignment module is presented to establish the unified evaluation system. This consists of the perception, concept, and decision analysis, which contributes to the adaptive cross-task analysis from the discrete sentiment space to the continuous sentiment space. The above joint analysis of the evaluation system and modality number indeed leads to the more flexible and generable multimodal sentiment semantic decoding paradigm. The experiments demonstrate that our sentiment semantic analysis network can achieve state-of-the-art performance.

While various deep learning techniques for electroencephalogram (EEG)-based brainprint recognition have achieved considerable success, these models remain vulnerable to adversarial attacks. However, existing black-box attack methods suffer from an inherent trade-off between query efficiency and distortion level. To address this challenge and further investigate the security risks of brainprint recognition systems in real-world black-box scenarios, we propose a query-efficient, low-distortion black-box attack method that targets the high-frequency components of EEG signals. Our approach innovatively selects sparse sampling points to estimate more accurate gradient information and leverages historical gradients to guide the prioritization of important points, thereby accelerating the attack process. The perturbations are applied in the high-frequency domain of the EEG signal to enhance stealth and effectiveness. Extensive experiments under black-box settings demonstrate that our method achieves state-of-the-art performance across two datasets and four models. Compared to existing methods, our approach significantly improves attack success rates while reducing the number of queries and minimizing distortion to imperceptible levels, thus achieving a superior balance between query efficiency and perturbation stealth.

Recent works on visual classification tasks have leveraged EEG signals to provide additional supervisory information, further improving the performance of the models on natural images. However, previous methods often force machine models to directly match EEG signals, which involves the transfer of modal-specific representations, leading to potentially distorted alignment of modal-shared representations. Moreover, focusing solely on aligning individual sample features neglects the alignment of relationships between samples, making it difficult to capture the potential relational reasoning capabilities in EEG signals. This relational reasoning ability is key to the human brain’s outstanding performance in visual classification tasks. Similarly, for a machine model, the complex relationships between instances are more critical than individual instances. Inspired by this, our idea is to enhance machine visual classification capabilities by imparting human-like relational reasoning, encouraging machine models to focus on the relational structure within EEG signals. To this end, we propose a brain-machine relation alignment method that constructs a cognitive model and a visual model to process EEG signals and visual images, respectively. Instead of forcing the visual model to mimic the output of an individual EEG data sample represented by the cognitive model, we encourage it to learn the mutual relations of EEG data samples. By penalizing the difference in relational structures between EEG signals and visual images, we facilitate the transfer of relational knowledge. Experiments demonstrate that the proposed method significantly improves the classification performance of the visual model. This highlights the potential of relational alignment as a robust mechanism for integrating human relational reasoning into machine learning models.

Abstract Insulators, as typical equipment for distribution networks, provide good electrical insulation between live conductors and earth. Timely and accurate detection is essential for insulator detection issues. However, as the complexity of neural networks increases, the detection efficiency is often lower. Therefore, this paper proposes a fast insulator positioning and defect detection method. Firstly, for insulator target localization, the SqueezeNet network is improved using ECA attention mechanism. In addition, to address the issue of low defect detection accuracy, a joint algorithm has been proposed. The integration of convolutional variational autoencoder (CVAE) and generative adversarial network (GAN) solve their own shortcomings due to different image focus angles. The target localization accuracy reaches 94.30%, and the defect detection accuracy reaches 89.60%. It solves the problems of difficulty in locating small targets in a large field of view and inaccurate detection due to a small number of abnormal samples. This method has been tried and tested in practical distribution network systems.

In this paper, we propose an improved distributed fusion algorithm under the Labeled multi-Bernoulli (LMB) filter framework. Firstly, the LMB parameter set is augmented by a new group variable, which is able to record the matching information of the neighbour sensors. Then the matching LMB components of the survival targets between the sensors can be fused directly by checking the group variable, greatly reducing the time cost of the matching calculation and the interference from the newborn targets. While for the newborn targets, the Murty algorithm is employed and only performed once to find the best matching relation between the sensors. Finally, experimental results show that the proposed algorithm offers a better tracking performance than the state-of-the-art R-GCI-LMB algorithm with lower computational complexity and higher tracking accuracy.

Due to the weak and nonstationary properties, electroencephalogram (EEG) data present significant individual differences. To align data distributions of different subjects, transfer learning showed promising performance in cross-subject EEG emotion recognition. However, most of the existing models sequentially learned the domain-invariant features and estimated the target domain label information. Such a two-stage strategy breaks the inner connections of both processes, inevitably causing the suboptimality. In this article, we propose a joint EEG feature transfer and semisupervised cross-subject emotion recognition model in which the shared subspace projection matrix and target label are jointly optimized toward the optimum. Extensive experiments are conducted on SEED-IV and SEED, and the results show that the emotion recognition performance is significantly enhanced by the joint learning mode and the spatial-frequency activation patterns of critical EEG frequency bands and brain regions in cross-subject emotion expression are quantitatively identified by analyzing the learned shared subspace.