1. Detection and Modeling of Vegetation Phenology Spatiotemporal Characteristics in the Middle Part of the Huai River Region in China Xu, Di; Fu, Meichen 2015 Articles Functions, OrthogonalVegetation monitoringVegetation and climateEcologySustainabilityLand use--Planning
2. Online Learning in the Virginia Community College System Jaggars, Shanna; Xu, Di 2010 Articles Community colleges