Concept drift poses a challenge in the field of data stream mining. Most existing online deep learning methods rely on a single objective, failing to sufficiently capture the latent feature information embedded in the data, which hinders rapid adaptation to distribution changes. To address these issues, this paper proposes a Multi-objective Joint Optimization of Deep Network (MJOD) model. Specifically, the feature connection network (FCN) connects features from different layers via dense feature units, constructing an integrated classification objective to fully utilize both shallow and deep information for precise prediction. Subsequently, the feature refinement network (FRN) compares historical representative information with current data to build a compressed reconstruction objective, thereby capturing changes in data distribution. Furthermore, the feature enhancement network (FEN) extracts spatial structure information from the data and constructs an information balance objective to retain the information most relevant to the task. By jointly optimizing the integrated classification, compressed reconstruction, and information balance objectives, the model maximizes the utilization of feature information within the streaming data, enabling rapid learning of new distributions. Experimental results demonstrate that MJOD is superior to other baseline methods across various drift scenarios.

In image classification, the label quality of training data critically influences model generalization, especially for deep neural networks (DNNs). Traditionally, learning from noisy labels (LNL) can improve the generalization of DNNs through complex architectures or a series of robust techniques, but its performance improvement is limited by the discriminative paradigm. Unlike traditional ways, we resolve the LNL problems from the perspective of robust label generation, based on diffusion models within the generative paradigm. To expand the diffusion model into a robust classifier that explicitly accommodates more noise knowledge, we propose a Directional Label Diffusion (DLD) model. It disentangles the diffusion process into two paths, i.e., directional diffusion and random diffusion. Specifically, directional diffusion simulates the corruption of true labels into a directed noise distribution, prioritizing the removal of likely noise, whereas random diffusion introduces inherent randomness to support label recovery. This architecture enable DLD to gradually infer labels from an initial random state, interpretably diverging from the specified noise distribution. To adapt the model to diverse noisy environments, we design a low-cost label pre-correction method that automatically supplies more accurate label information to the diffusion model, without requiring manual intervention or additional iterations. Our approach outperforms state-of-the-art methods on both simulated and real-world noisy datasets. Code is available at https://github.com/SenyuHou/DLD.

Recently, the potential of lightweight models for resource-constrained scenarios has garnered significant attention, particularly in safety-critical tasks such as bio-electrical signal classification and B-ultrasound-assisted diagnostic. These tasks are frequently affected by environmental noise due to patient movement artifacts and inherent device noise, which pose significant challenges for lightweight models (e.g., deep binary neural networks (DBNNs)) to perform robust inference. A pertinent question arises: can a well-trained DBNN effectively resist environmental noise during inference? In this study, we find that the DBNN's robustness vulnerability comes from the binary weights and scaling factors. Drawing upon theoretical insights, we propose L1-infinite norm constraints for binary weights and scaling factors, which yield a tighter upper bound compared to existing state-of-the-art (SOTA) methods. Finally, visualization studies show that our approach introduces minimal noise perturbations at the periphery of the feature maps. Our approach outperforms the SOTA method, as validated by several experiments conducted on the bio-electrical and image classification datasets. We hope our findings can raise awareness among researchers about the environmental noise robustness of DBNNs.

The skewed class distribution and data complexity may severely affect the imbalanced classification results. The cost of classification can be significantly reduced if these data complexity are measured and pre-processed prior to training, particularly when dealing with large-scale and high-dimensional datasets. Although many methods have been proposed to evaluate data complexity, most of them fail to fully consider the interaction among different data characteristics, or the connection between class imbalance and these characteristics, thus posing a serious challenge to effectively evaluate the difficulty of classification. This paper presents a new data complexity measure MFII (multi-factor imbalance index), which measures the combined effects of the skewed class distribution and data characteristics on classification difficulty. In particular, it further comprehensively investigates the impact of overlap size, confusion degree, and sub-cluster structure. VoR (value of resolution) and DoC (degree of consistency) are also proposed to evaluate the resolution and interpretability of complexity measures. The experimental results demonstrate that MFII has lower VoR and a stronger correlation with classification metrics, which indicates that MFII can more accurately evaluate the difficulty of multi-class imbalanced classification tasks.

Class overlap is a major factor of data complexity that hampers classifier performance, particularly in imbalanced learning scenarios. Most existing oversampling methods rely on conservative seed sample selection and decoupled synthesis strategies, which limit sample diversity and fail to effectively control overlap risk. This paper proposes a novel oversampling framework called TMACO (Class Alliance-Constrained Oversampling), which integrates data complexity considerations into both seed selection and sample generation. First, TMACO selects seed sample units using a class alliance constraint that jointly considers spatial geometry and class distribution to enhance diversity and representativeness. Second, it generates synthetic samples based on three-point units to ensure regional stability. Third, a region-level filtering mechanism is applied to prevent synthetic samples from intruding into majority class areas. Extensive experiments on benchmark and real-world datasets demonstrate that TMACO consistently improves minority class performance and overall classification accuracy compared to state-of-the-art oversampling techniques. The proposed method also offers interpretable parameter control and adapts well to varying task objectives.

Concept drift is an important characteristic and inevitable difficult problem in streaming data mining. Ensemble learning is commonly used to deal with concept drift. However, most ensemble methods cannot balance the accuracy and diversity of base learners after drift occurs, and cannot adjust adaptively according to the drift type. To solve these problems, this paper proposes a targeted ensemble learning (Targeted EL) method to improve the accuracy and diversity of ensemble learning for streaming data with abrupt and gradual concept drift. First, to improve the accuracy of the base learners, the method adopts different sample weighting strategies for different types of drift to realize bidirectional transfer of new and old distributed samples. Second, the difference matrix is constructed by the prediction results of the base learners on the current samples. According to the drift type, the submatrix with appropriate size and maximum difference sum is extracted adaptively to select appropriate, accuracy and diverse base learners for ensemble. The experimental results show that the proposed method can achieve good generalization performance when dealing with the streaming data with abrupt and gradual concept drift.