Augmented reality (AR) scene modeling with virtual-real integration is an effective way to enhance users’ perception and understanding of geographic spaces. However, the existing modeling methods focus on precise virtual-real alignment in static scenes using single-frame images, leading to inefficiencies in dynamic scene modeling and low accuracy in virtual-real integration. This paper proposes a fast modeling method for AR dynamic scenes with spatio-temporal semantic constraints. By thoroughly analyzing spatio-temporal semantic constraint rules in AR dynamic scene modeling, a keyframe extraction algorithm based on a synchronized spatio-temporal semantic distance measurement model was designed. A rapid spatio-temporal interpolation model for AR dynamic view poses with spatio-temporal semantic association was established, and a real 3D scene-driven fast twin modeling method for AR dynamic scenes was proposed. Experimental results show that the proposed method reduces redundant image matching computations by 87.53% while maintaining virtual-real registration accuracy above 1°. This method enables accurate sampling of keyframes with spatio-temporal homogeneity, avoids redundant transmission of large volumes of frame image data, and improves AR dynamic scene virtual-real registration efficiency while maintaining accuracy. Furthermore, the spatial semantic information in real 3D scenes effectively guides fast AR dynamic scene modeling.

In recent years, blockchain technology has developed rapidly and received widespread attention. However, its pseudonymous and decentralized nature has also attracted many criminal activities. Ponzi schemes, a kind of classic financial scam, also hide their true face in smart contracts, causing massive financial losses to blockchain users. Although several methods have been proposed to detect Ponzi contracts, there are still limitations in broad applicability, semantics understanding, and adversarial robustness. In this article, we propose PonziHunter, an intelligent framework for hunting Ponzi contracts on Ethereum. To tackle the problem of broad applicability, we train a detection model that does not require expert experience based on publicly available on-chain bytecode and off-chain contract labels. To tackle the problem of semantics understanding, we employ cross-function control flows and state variable dependencies to understand the logic of Ponzi contracts. Specifically, we decompile bytecodes into higher-order representations to analyze control flows and state variable dependencies and model the information as graph data. By combining the idea of code slicing, we identify the basic blocks related to Ponzi contract recognition. To tackle the problem of adversarial robustness, we model Ponzi contract recognition as a graph classification problem based on contrastive pre-training. We propose a data augmentation method for control flow graphs (CFGs), which preserves the basic blocks related to Ponzi contract recognition as much as possible during data perturbation. Experimental results show that PonziHunter outperforms state-of-the-art tools with average improvements of at least 4.77% on real-world ground-truth data and can newly discover 85 Ponzi contracts in the wild. More importantly, PonziHunter is robust against adversarial examples and can locate the critical basic blocks for smart Ponzi detection.

An important step in implementing geospatial digital twins is to enhance the expressiveness of virtual geographical scenes for the physical world. However, the existing virtual geographical scenes cannot quickly express the dynamically changing geographic environment for remote users due to the inefficient handling of modeling processes, user perception, and remote sharing. The research analysed the concept and characteristics of geospatial digital twins, and constructed the virtual geographical scene ontology, based on which we developed geographical spatiotemporal semantic rules and designed a dynamic annotation algorithm to enhance the representation of virtual geographical scenes. Finally, we investigated a real-time transmission method of panoramic video based on 5 G and used immersive virtual reality (IVR) to realize the user experience of remote immersion in geographical scenes. We selected a specific geographic environment containing multiple typical geographic entities to develop three prototype systems for experimental analyses. The results showed that the proposed method enabled users to view the virtual geographical scene on a VR device. The average latency for this process was 14.72 seconds. Compared with the virtual geographical scenes constructed by traditional methods, the experiments showed the proposed method advantageous in comprehensiveness, timeliness, and photorealism and abilities to enhance the user’s geographical scene perception.

The detail and representation of a spatial layout varies with scale. This affects an individual’s learning effectiveness and understanding, in turn directly influencing their behavior in a fire evacuation. However, the impact of layout learning methods with different spatial scales on fire evacuation behavior, and the relationship between spatial cognition and evacuation effects, remains unclear. We conducted spatial layout learning across three scales with 81 participants and simulated a fire evacuation scenario in a mobile virtual reality for groups. We collected evacuation decision-making and user experience questionnaires as supplementary data. The results demonstrate that small-scale learning objects are the easiest for participants to understand in terms of spatial layout and relationships, but their performance in fire evacuation is poor. Large-scale learning objects significantly improve participants’ evacuation efficiency. Spatial layout learning plays a crucial role in fire evacuation outcomes, but traditional spatial knowledge acquisition measurement methods cannot predict fire evacuation performance. This study sheds light on how spatial cognition influences fire evacuation behavior and provides a more reliable fire evacuation simulation method based on mobile virtual reality (MVR).

As an important application of virtual geographic environments (VGEs), virtual disaster scenes are essential in enhancing the public’s risk awareness. However, existing virtual disaster scene visualization methods lack expert guidance and fail to meet the public’s requirements, resulting in an ineffective public understanding. Therefore, this paper proposes a knowledge-guided disaster scene 3D visualization framework. First, the public’s demand for disaster scene visualization is analyzed, and a geographic knowledge graph of disaster scenes is constructed. Second, through the guidance of the knowledge graph, the virtual disaster scenes are fusion modeled and suitability represented. Third, a diverse organization and adaptive scheduling method of disaster scene data for multi-computing devices is established. Finally, we developed a prototype system for disaster scene visualization, selected a typical disaster, and conducted cognitive experiments with eye-tracking technology. The results show that the proposed method can effectively support the adaptive visualization of virtual disaster scenes for four computing devices and maintain an efficient frame rate. In addition, compared with other disaster scene visualization methods, our framework incorporates semantic knowledge of scene, user, demand, and space. It can effectively convey disaster information and help the public cognize disaster risks and has significant advantages in modeling standardization, personalization, and adaptability.

Patients of depression often have lower performance in perception, planning, and execution in cognition, compared to healthy controls. Depression has been reported to be associated with functional alterations in the resting state connectivity in the brain. This study investigates whether there are differences in neural dynamics measured by mental arithmetic tasks (MAT) between depressed and healthy subjects. To this end, this study employed an ROI-based functional connectivity analysis, within-condition interregional covariance analysis (WICA), to explore the correlates of the brain deactivation regions. Results of this study showed that the corresponding emotional loop is inhibited in healthy subjects and show the control loops of attention and emotion is inhibited in depressed subjects during MAT, and the patients with depression may produce a stronger stress response than the healthy subjects during the MAT. This may be the key reason for that the mathematical abilities of the depression subjects were inferior to that of the healthy subjects.