Addressing the persistent challenge of learning from imbalanced datasets is crucial in advancing machine learning applications. Standard machine learning algorithms typically assume that the input data is balanced, and they often struggle to effectively learn the distribution of minority class data when dealing with imbalanced data. To address this, our study designed an improved Generative Adversarial Networks (GANs) model, named MDGAN, for tabular sample synthesis to augment samples and balance the data distribution. MDGAN employs a multi-generator and multi-discriminator structure to capture non-connected subspace manifolds, thereby better fitting the complete data distribution. To enhance the diversity among the multiple generators, an exclusive loss among generators was designed, ensuring that each generator produces data of different modalities. Additionally, a contrastive loss was introduced to ensure that the generated samples better fit the minority class distribution and are separated from the majority class distribution, preventing blurred classification boundaries. Qualitative and quantitative tests were conducted on 25 real datasets, and the experimental results indicate that MDGAN outperforms traditional classical models and current advanced oversampling models.

Infrared small target detection (IRSTD) based on deep learning has received extensive research and application. However, deep learning models require a large amount of data to perform well, and the collection and standardization of infrared small target data is challenging, limiting the applicability of such models. To address this issue, this study proposes a data augmentation scheme for infrared small targets based on Generative Adversarial Networks (GANs). The proposed method is a two-step approach: the first step is the generation of clean backgrounds, and the second is the adaptive fusion of targets and backgrounds. In the background generation stage, we first use the Fast Marching Method (FMM) to fill background targets and obtain clean backgrounds. Then, we design a multi-generator and multi-discriminator GAN model (MGD-GAN) to generate high-quality and diverse background images. In the adaptive target-background fusion stage, we propose a dual-discriminator GAN network (FusionGAN), which allows the target mask to be adaptively fused with the background pixels. By combining real targets with generated backgrounds, new infrared small target images are generated, achieving the goal of data augmentation. Experiments conducted across three different scenarios demonstrate that the proposed data augmentation scheme effectively enhances the performance of both traditional and advanced detection models.

Recently, convolutional neural networks have yielded promising results in infrared small target detection. However, limited data is a main restriction to the further promotion of detection performance. To solve this issue, we propose a novel two-stage synthetic data augmentation method, involving StyleGAN-based background generation and Transformer-based target fusion, which aims at generating diverse infrared small target images fitting the original distribution. In the background generation stage, we devise a spatial and low-frequency StyleGAN to ameliorate background generation quality, effectively adapting to less high-frequency information in infrared images. In the target fusion stage, a target prior-based Transformer model with a new detecting difficulty distribution similarity loss is proposed to modulate the intensity of targets implanted on synthetic backgrounds. Experimental results show that our synthetic data augmentation method greatly improves the performance of four detection models on three public datasets and attains state-of-the-art results compared to existing data augmentation methods.

The big data of Internet of Vehicles contributes to the development of intelligent transportation. Privacy protection in vehicular ad hoc networks (VANETs) is the core factor to improve user and vehicle participation. This article proposes a novel blockchain-based dynamic extensible privacy protection and message authentication scheme for VANETs. It minimizes the computation cost of message authentication based on an elliptic curve and message batch verification. Based on the Chinese remainder theorem, this scheme protects transmitted message security by adaptively and dynamically responding to vehicles and roadside units accessing the VANET. It offers a smart contract-based forensics and tracing solution from the accident vehicle. In addition, strict security proof and analysis that the scheme meets the security requirements for the VANET. It evaluates the efficiency of the scheme, and the results show its practicality.

Internet of Things (IoT) devices are large in number, widely distributed, weak in protection ability, and vulnerable to various malicious attacks. Intrusion detection technology can provide good protection for network equipment. However, the normal traffic and abnormal traffic in the network are usually imbalanced. Imbalanced samples will seriously affect the performance of machine learning detection algorithm. Therefore, this paper proposes an intrusion detection method based on data augmentation, namely TMG-IDS. We name the proposed data augmentation model TMG-GAN, which is a data augmentation method based on generative adversarial networks (GAN). First, TMG-GAN has a multi-generator structure, which can be used to generate different types of attack data simultaneously. Second, we increase the classifier structure, which can optimize the generator and discriminator more efficiently based on the classification loss. Third, we calculate the cosine similarity between the generated samples and the original samples and other types of generated samples as a generator loss, which can further improve the quality of generated samples and reduce the class overlap area between the distributions of various generated samples. We conduct extensive experiments on two intrusion detection datasets, CICIDS2017 and UNSW-NB15. The experimental results show that compared with the advanced oversampling algorithm and the latest intrusion detection algorithm, the proposed TMG-IDS method has a good detection effect under the three indicators of Precision, Recall and F1-score.

The barriers of food enterprises and departments caused information asymmetry, which is the root cause of food safety incidents. Simultaneously, it is challenging to solve the information asymmetry by the existing cloud-based food supply-chain regulation system. Establishing a secure and reliable data sharing environment is an effective solution to the information island. Blockchain can construct a security network based on mathematical algorithms, eliminating the third party’s potential security risk, and realize transparently share data. In this paper, on the principle of metadata remaining in the food enterprises, we propose a blockchain-cloud fusion scheme based on Decentralized Attribute-Based Signature (DABS) to realize secure data sharing between departments. It constructs a decentralized and trusting environment for data owners to share data and achieves social co-governance of food safety based on the smart contract. It can also preserve the existing system architecture and complement the performance disadvantage of blockchain and cloud storage. The result achieved from security analysis shows that our scheme supports unconditional full anonymity and can resist collusion attacks of N-1 out of N corrupted attribute authorities.