The 13th issue of the Transactions on Computational Science journal consists of two parts. The six papers in Part I span the areas of computing collision probability, digital image contour extraction, multiplicatively weighted Voronoi diagrams, multi-phase segmentation, the rough-set approach to incomplete information systems, and fault-tolerant systolic arrays for matrix multiplications. The five papers in Part II focus on neural-network-based trajectory prediction, privacy in vehicular ad-hoc networks, augmented reality for museum display and the consumer garment try-on experience, and geospatial knowledge discovery for crime analysis.