The coasts of Guangdong-Hong Kong-Macao Greater Bay Area (GBA) are facing threats and challenges from rising sea levels, frequent extreme events and human intervention. In this study, the Coastal Hazard Wheel (CHW) was used to classify the coasts of GBA, assess its hazard change from 2010 to 2020, identify hazards hotspots and explore available coastal management options. The results show that the coastal types of GBA in 2010 and 2020 are consistent, with delta/low estuary island and hard rock slope as the main types. GBA is vulnerable to ecosystem disruption, saltwater intrusion, gradual inundation and flooding hazards. Compared with 2010, the high risk proportion of each hazard in 2020 decreased significantly, but the high risk of flooding increased slightly. All kinds of hazards are interdependent and influenced by each other. The Pearl River Estuary, the east bank of Yamen Waterway, the west bank of Huangmao Sea and Dapeng Bay show very high hazard vulnerability, and the flooding risk is the highest. Soft measures such as coastal zoning, tsunami warning systems, wetland restoration and hazard simulation are most widely used in coastal management. CHW is applicable to GBA’s coastal hazard vulnerability assessment, which provides a case study for coastal risk assessment of GBA and has certain reference significance for hazard management and sustainable development for the Bay Area.

The traditional particle swarm optimization (PSO) algorithm often exhibits defects such as of slow convergence and easily falling into a local optimum. To overcome these problems, this paper proposes an enhanced variant featuring adaptive selection. Initially, a composite chaotic mapping model integrating Logistic and Sine mappings is employed to initialize the population for diversity and exploration capability. Subsequently, the global and local search capabilities of the algorithm are balanced through the introduction of adaptive inertia weights. The population is then divided into three subpopulations—elite, ordinary, and inferior particles—based on their fitness values, with each group employing a distinct position update strategy. Finally, a particle mutation strategy is incorporated to avoid convergence to local optima. Experimental results demonstrate that our algorithm outperforms existing algorithms on the standard benchmark functions. In practical engineering applications, our algorithm also has demonstrated better performance than other meta heuristic algorithms.

Among many coastal hazards, rip currents have gradually become one of the most noticeable hazards. Studies have demonstrated that most drowning accidents at beaches around the world are related to rip currents. In this study, online and field questionnaires were combined for the first time to reveal beachgoers’ awareness of rip currents in China from four aspects: demographic characteristics, swimming ability, information about visiting beaches, and knowledge about rip currents. One educational strategy was introduced to the field survey. The results suggest that (i) the proportion of online and field respondents who have heard of “rip currents” and seen warning signs of rip currents is extremely small. This reflects that beachgoers lack awareness of rip current hazards. Thus, China needs to strengthen the safety education of rip current knowledge. (ii) The level of awareness of rip currents can significantly affect the community’s ability to identify the location of rip currents and their choice of escape direction. (iii) In the field survey, we implemented an educational strategy as an intervention for respondents, and the accuracy of identifying rip currents and choosing the correct escape route improved by 34% and 46.7%, respectively. This implies that the intervention of educational strategy can significantly deepen beachgoers’ awareness of rip currents. It is recommended that more educational strategies about rip current knowledge be implemented on Chinese beaches in the future.

Rip currents are fast offshore currents and a critical component of nearshore circulation, significantly influencing public safety and material transport. This study employs the Generalized Additive Model, an effective approach for uncovering complex nonlinear relationships, to provide a comprehensive quantitative understanding of rip current drivers. By integrating field observations from a headland beach in southern China with Delft3D numerical modeling, which incorporates wave‐current coupling, the contributions and interactions of environmental factors to low‐energy rip current generation were quantified. Results indicate that rip currents form only within specific parameter combinations, with an annual occurrence rate of 5.9% in the study area. Significant nonlinear relationships were found between rip current generation and key environmental factors, including wave period (Period), significant wave height (SWH), wave direction (Direction), wind direction (WindDir), and water level. Variations in Direction and SWH were particularly influential. The formation of rip currents depends on the interaction of environmental factors, and the response to a single factor diminishes if other factors have not reached their thresholds. Certain environmental factor ranges, while not strongly influencing rip current velocity, can significantly increase rip current frequency. This distinction between rip current velocity (hazard intensity) and frequency provides novel insights into rip current generation mechanisms and supports the development of early warning systems.

A mixed matching circuit for miniaturizing dual-band antenna is introduced and verified in this study. Two L-shaped matching circuit for miniaturization are cascaded to interpret the theory of operation in accordance with the dual-band allocations on the Smith chart. A matching circuit equation is deduced based on a bidirectional matching track from a certain position to the origin point on the Smith chart. Furthermore, a dual-band antenna is taken as an example to illustrate the performance of the novel matching approach for miniaturization. The occupation of a dual-band antenna can be reduced by a quarter at the simultaneous operational frequencies of 2.4 and 5.8 GHz. Lastly, a dual-band planar inverted-F antenna (PIFA) is developed and examined. The experimental results are well consistent with those in the simulator.