Herein, the spatial evolution characteristics of high-level Grade A tourist attractions in the Yangtze River Delta (YRD) urban agglomeration, from 2001 to 2021, are studied by comprehensively applying the nearest neighbor index, kernel density analysis, standard deviation ellipse, and spatial autocorrelation.High-level Grade A tourist attractions a

The existence of three-dimensional effects at cracks has been known for many years, but understanding has been limited, and for some situations still is.Understanding improved when the existence of corner point singularities and their implications became known.Increasingly powerful computers made it possible to investigate three-dimensional effects