Perception Enhanced Deep Deterministic Policy Gradient for Autonomous Driving in Complex Scenarios

Autonomous driving has witnessed rapid advancement;however,ensuring safe and efficient driving in intricate scenarios remains a critical challenge.In particular,traffic roundabouts bring a set of challenges to autonomous driving due to the unpredictable entry and exit of vehicles,susceptibility to traffic flow bottlenecks,and imperfect data in perceiving environmental information,rendering them a vital issue in the practical application of autonomous driving.To address the traffic challenges,this work focused on complex roundabouts with multi-lane and proposed a Perception EnhancedDeepDeterministic Policy Gradient(PE-DDPG)for AutonomousDriving in the Roundabouts.Specifically,themodel incorporates an enhanced variational autoencoder featuring an integrated spatial attention mechanism alongside the Deep Deterministic Policy Gradient framework,enhancing the vehicle’s capability to comprehend complex roundabout environments and make decisions.Furthermore,the PE-DDPG model combines a dynamic path optimization strategy for roundabout scenarios,effectively mitigating traffic bottlenecks and augmenting throughput efficiency.Extensive experiments were conducted with the collaborative simulation platform of CARLA and SUMO,and the experimental results show that the proposed PE-DDPG outperforms the baseline methods in terms of the convergence capacity of the training process,the smoothness of driving and the traffic efficiency with diverse traffic flow patterns and penetration rates of autonomous vehicles(AVs).Generally,the proposed PE-DDPGmodel could be employed for autonomous driving in complex scenarios with imperfect data.

Surface plasmon polariton waveguides with subwavelength confinement

Surface plasmon polaritons（SPPs） are evanescent waves propagating along metal-dielectric interfaces, which provide an effective way to realize optical wave guiding with subwavelength confinement. Metallic nanostructures supporting SPPs,that is, plasmonic waveguides, are considered as required components to construct nanophotonic devices and circuits with a high degree of miniaturization and integration. In this paper, various types of plasmonic waveguides operating in the visible, infrared, and terahertz regions are reviewed, and the status of the research on their fundamentals, fabrications,and applications is provided as well. First, we discuss the mechanisms of SPPs beyond the diffraction limit, and their launching methods. Then, the characteristics of SPPs on various plasmonic waveguides are reviewed, including top-down and bottom-up fabricated types. Considering applications, certain prototypes of plasmonic devices and circuits constructed by plasmonic waveguides for bio/chemo sensing, router, and light modulation are demonstrated. Finally, a summary and future outlook of plasmonic waveguides are given.