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Global change refers to changes in the relationship between humans and nature. It is desirable to actively integrate human social activities into the unified framework of global change so that thei...

Airborne laser scanning (ALS) has recently been identified as a potential tool in topographic mapping for archaeological prospection. However, most existing applications in this field refers to man...

Sliding mode control and disturbance compensation techniques are applied to a nonlinear speed control algorithm for a permanent magnet synchronous motor (PMSM). Optimizing the speed control performance of PMSM systems with various disturbances and uncertainties is challenging. To achieve a satisfactory performance, a sliding mode control method based on the super-twisting algorithm reaching law (STRL) is presented. STRL can adapt dynamically to the variations of a controlled system. The STRL maintains a high tracking performance of the controller and allows the control input to eliminate chattering. To estimate the uncertainties and compensate for disturbances, a support vector regression-disturbance observer (SVR-DOB) is presented. The estimated uncertainties were used to minimize modeling errors and improve the disturbance rejection. A controller using SVR-DOB achieves a high precision, and the simulation results demonstrated the validity of the proposed control approach.

The traditional logistics vehicle tracking method lacks the function of active identification and switch tracking. Therefore, in the presence of interference, there are some problems such as interf...

An evacuation model combining alterable accessibility and human awareness.The agent awareness of accessibility is reflected by both spatial and event knowledge.The alterable accessibility is represented by a semantic model and is timely updated.The spatial change has a negative effect when detouring occurs due to a lack of knowledge.The spatial change has a positive effect when the exit utilization is balanced. The building environment and evacuation behavior are decisive factors for building evacuation performance. Shifting toward the use of agent-based models, many current studies have considered the heterogeneous evacuation behavior resulting from an individualized perception of the building environment, but few studies have incorporated the evacuees' awareness of the predictable change in the spatial accessibility by activated fire safety facilities during emergency scenarios. To investigate the specific influence of such spatial change on the evacuation performance, this study presents an agent-based building evacuation model in which the evacuee's knowledge, including both the spatial knowledge of the stationary environment during a normal situation and the event knowledge of the predictable spatial change for fire-fighting purposes, is considered. In addition, a semantic representation of building environment is developed to represent the alterable connectivity structure when considering the fire safety facilities. Using the proposed model, a series of evacuation simulations have been conducted for groups of evacuees with different knowledge levels during three specific fire scenarios. The simulation results suggest that the proposed model can evaluate the potential influence of the spatial change on the evacuation efficiency, which is dependent on the evacuees' knowledge level and the location of the fire safety facilities. The model, although a prototype at this stage, will facilitate more realistic evacuation simulation in fire emergency scenarios and will support building evacuation management.

This article presents a method of noise measurement using reality–virtuality fusional avatar and the real-time visualization of noise in an online virtual geographic environment (VGE). The reality–virtuality fusional avatar links the user with his/her avatar in the virtual world. Therefore, noise data collected by the users in the real world can be simultaneously visualized in the virtual world. A framework of reality–virtuality fusional avatar was proposed and implemented based on OpenSimulator (OpenSim). The noise data was collected by mobile phones with a sensing application called ISEISense. Preliminary experiment was carried out in the Chinese University of Hong Kong campus. It is expected that such a reality–virtuality fusional avatar will be able to support public-participated noise measurement through online VGE.

Many of the world's powerful and wealthy nations, including China, have devoted both large amounts of funding and considerable promotion to lunar research and exploration. The launch of Chinese Chang'e-1 satellite and the construction of the scientific observation data platform created a favourable opportunity for research into the lunar geometrical, physical and chemical environment. Based on this background, a Wide Area Network (WAN) based virtual lunar environment was constructed for observation data sharing and further exploration. The systematic architecture and framework were introduced and then strategies of mass data (e.g. lunar digital elevation model, lunar digital orthophoto map and typical thematic lunar data) organisation, integration, management and scheduling were then set up to achieve the 3D visualisation of typical lunar geomorphic features. Furthermore, the integration method of 3D lunar data and the process model of impact craters were studied; thus, the whole lunar and celest...

The integration of high dimensional geo-visualization, geo-data management, geo-process modeling and computation, geospatial analysis, and geo-collaboration is a trend in GIScience. The technical platform that matches the trend forms a new framework unlike that of GIS and is conceptualized in this paper as a collaborative virtual geographic environment (CVGE). This paper focuses on two key issues. One is scientific research on CVGE including the concept definition and the conceptual and system framework development. The other is a prototype system development according to CVGE frameworks for air pollution simulation in the Pearl River Delta. The prototype system integrates air pollution source data, air pollution dispersion models, air pollution distribution/dispersion visualization in geographically referenced environments, geospatial analysis, and geo-collaboration. Using the prototype system, participants from geographically distributed locations can join in the shared virtual geographic environment to conduct collaborative simulation of air pollution dispersion. The collaborations supporting this simulation happen on air pollution source editing, air pollution dispersion modeling, geo-visualization of the output of the modeling, and geo-analysis.

This paper introduces a scalable virtual learning environment of the Chinese University of Hong Kong; an explicitly geographical, immersive, and sharable 3D learning space with comprehensive social elements. It is characterized by multi-user collaborative modeling, group learning approaches of geo-collaboration, social space-oriented hierarchical avatars, and knowledge exchanging and sharing based on virtual geographic experiments. Applications for the purpose of public education and virtual geographic experiment, and indicated future works prove the possibility to offer a greater opportunity to foster interdisciplinary collaborations, revitalize teaching patterns and learning contents, improve learners' cognitive abilities to solve problems, and enhance their understanding of scientific concepts and processes.