Ask HN: Open Source machine learning research

Hi. I'm looking for any links to machine learning/AI research work being conducted by or through open source software programs. Something like Collaborative Filtering by MLPACK (done in 2014) or open source search engines, data analysis of time series or the like. Projects/research which are looking for volunteers - something like OpenCV - for Computer Vision and/or Graphics are also something similar I'm interested in. Any help would be appreciated.