Urban Traffic Flow Prediction Model with CPSO/SSVM Algorithm under the Edge Computing Framework

Urban traffic flow prediction has always been an important realm for smart city build-up. With the development of edge computing technology in recent years, the network edge nodes of smart cities are able to collect and process various types of urban traffic data in real time, which leads to the possibility of deploying intelligent traffic prediction technology with real-time analysis and timely feedback on the edge. In view of the strong nonlinear characteristics of urban traffic flow, multiple dynamic and static influencing factors involved, and increasing difficulty of short-term traffic flow prediction in a metropolitan area, this paper proposes an urban traffic flow prediction model based on chaotic particle swarm optimization algorithm-smooth support vector machine (CPSO/SSVM). The prediction model has built a new second-order smooth function to achieve better approximation and regression effects and has further improved the computational efficiency of the smooth support vector machine algorithm through chaotic particle swarm optimization. Simulation experiment results show that this model can accurately predict urban traffic flow

Investigation on the Hydrogeochemical Characteristics and Controlling Mechanisms of Groundwater in the Coastal Aquifer

Groundwater contamination in coastal areas has attracted widespread attention. However, studies on the hydrogeochemical characteristics and controlling mechanisms in coastal aquifers are still lacking. In this study, 71 sets of groundwater samples were collected during the dry and wet seasons in a coastal city, Shandong Province. Correlation and principal component analyses were used to identify pollution sources. Meanwhile, Piper diagrams, Gibbs plots, ion ratios, and saturation indices were employed to investigate the hydrogeochemical controlling mechanisms. The results revealed that pollution components included Na+, NH4+, Cl−, SO42−, NO3−, NO2−, Pb, As, Se, TDS, TH, F−, and Mn. Pollution compositions in the study area were primarily derived from natural processes and anthropogenic activities. The contamination of nitrogen resulted primarily from agricultural activities. The exceedance of SO42− was mainly due to the leaching of waste by rainfall. High Na+, Cl−, and F− were related to sea intrusion. Pb and Se might have been caused by anthropogenic activities. The exceedance of As was caused by anthropogenic inputs and natural factors. The poor seepage conditions and anoxic conditions promoted the enrichment of Mn. The concentration of most components in the dry season was larger than that in the wet season. There were no significant differences in water chemistry type during the wet season and dry season. Groundwater chemical compositions were dominated by the dissolution of halite, gypsum, and anhydrite, as well as the cation exchange reaction. The influence of seawater intrusion on groundwater was not serious

A Comprehensive Review of Recent Progress on GaN High Electron Mobility Transistors: Devices, Fabrication and Reliability

GaN based high electron mobility transistors (HEMTs) have demonstrated extraordinary features in the applications of high power and high frequency devices. In this paper, we review recent progress in AlGaN/GaN HEMTs, including the following sections. First, challenges in device fabrication and optimizations will be discussed. Then, the latest progress in device fabrication technologies will be presented. Finally, some promising device structures from simulation studies will be discussed