Numerical analysis on transitions and symmetry-breaking in the wake of a flapping foil

Flying and marine animals often use flapping wings or tails to generate thrust. In this paper, we will use the simplest flapping model with a sinusoidal pitching mo- tion over a range of frequency and amplitude to investigate the mechanism of thrust generation. Previous work focuses on the Karman vortex street and the reversed Karman vor- tex street but the transition between two states remains un- known. The present numerical simulation provides a com- plete scenario of flow patterns from the Karman vortex street to reversed Karman vortex street via aligned vortices and the ultimate state is the deflected Karman vortex street, as the parameters of flapping motions change. The results are in agreement with the previous experiment. We make further discussion on the relationship of the observed states with drag and thrust coefficients and explore the mechanism of enhanced thrust generation using flapping motions.

A review on cooperative perception and control supportedinfrastructure-vehicle system

With the rapid development of connected autonomous vehicles(CAVs),both road infrastructure and transport are experiencing a profound transformation.In recent years,the cooperative perception and control supported infrastructure-vehicle system(IVS)attracted increasing attention in the field of intelligent transportation systems(ITS).The perception information of surrounding objects can be obtained by various types of sensors or communication networks.Control commands generated by CAVs or infrastructure can be executed promptly and accurately to improve the overall performance of the transportation system in terms of safety,efficiency,comfort and energy saving.This study presents a comprehensive review of the research progress achieved upon cooperative perception and control supported IVS over the past decade.By focusing on the essential interactions between infrastructure and CAVs and between CAVs,the infrastructure-vehicle cooperative perception and control methods are summarized and analyzed.Furthermore,the mining site as a closed scenario was used to show the current application of IVS.Finally,the existing issues of the cooperative perception and control technology implementation are discussed,and the recommendation for future research directions are proposed.