Search Results (3)

Most image forgery localization methods rely on supervised learning, requiring large labeled datasets for training. Recently, several unsupervised approaches based on the variational autoencoder (VAE) framework have been proposed for forged pixel detection. In these approaches, the latent space is built by a simple Gaussian distribution or a Gaussian Mixture Model. Despite their success, there are still some limitations: (1) A simple Gaussian distribution assumption in the latent space constrains performance due to the diverse distribution of forged images. (2) Gaussian Mixture Models (GMMs) introduce non-convex log-sum-exp functions in the Kullback–Leibler (KL) divergence term, leading to gradient instability and convergence issues during training. (3) Estimating GMM mixing coefficients typically involves either the expectation-maximization (EM) algorithm before VAE training or a multilayer perceptron (MLP), both of which increase computational complexity. To address these limitations, we propose the Deep ViT-VAE-GMM (DVVG) framework. First, we employ Jensen’s inequality to simplify the KL divergence computation, reducing gradient instability and improving training stability. Second, we introduce convolutional neural networks (CNNs) to adaptively estimate the mixing coefficients, enabling an end-to-end architecture while significantly lowering computational costs. Experimental results on benchmark datasets demonstrate that DVVG not only enhances VAE performance but also improves efficiency in modeling complex latent distributions. Our method effectively balances performance and computational feasibility, making it a practical solution for real-world image forgery localization. Full article

In electrified transportation systems, power system failures can lead to greater disasters. Therefore, the reliability of converters in transportation systems has been a concern. Fault-tolerant techniques are widely applied to ensure that converters can continue to supply loads under fault conditions. Fault diagnosis as a prerequisite for fault tolerance has also become a research hotspot. This paper proposes a fast method for fault diagnosis of high-frequency LLC converters. The proposed fault diagnosis method is based on the observation of the voltage across the resonant capacitor to determine and locate the faulty power switch, providing a basis for fault tolerance. This diagnosis method requires a voltage sensor, which is also necessary for some control methods. When applying these control methods, the proposed fault diagnosis method can be used without additional sensors, beneficial for cost reduction. A full-bridge LLC converter controlled by a digital signal processor was used as an experimental platform to verify the effectiveness and speed of the proposed diagnostic method. The results show that the proposed fault diagnosis method can achieve the fast diagnosis of high-frequency LLC converters in a short time and with only minimal computational resources. Full article

Landscape is an important object for research on local culture from a cultural geographical perspective. It is the spatial nature of memory that has seen the integrative study of memory and landscape receive increased attention from human geographers. The Qiqiao Festival is a traditional folk festival in the Lingnan region of Southern China. After half a century of suppression, the Qiqiao Festival in Zhucun was publically revitalized as the Guangzhou Qiqiao Cultural Festival, which coincided with the changing structure and significance of the landscape. This paper selected Zhucun, a typical urban village, as its case study and constructed an index system of festival landscapes. Through in-depth interviews, this paper studied the revival and restructure process of the Qiqiao Festival, and the role that landscapes play in the formation mechanism of memory on the part of subjects with different identities. The results showed that the elite and the local government selectively restructure festival landscapes, replacing authentic landscapes with “official” ones. The selection and production of a festival landscape constructed different memories among the subjects, where the festival memory of grassroots villagers was self-constructed and mostly came from traditional festival landscape elements while top-down interventions in the festival landscape constructed a different “official” memory for citizens and migrants to those of the villagers. The contemporary festival deviates from the original, which has weakened the conscious degree of cultural evolution and has had a reaction on the authenticity of memory. This research serves a reference for approaches in planning and conserving intangible cultural heritage in historic villages. Full article