EMAN (Electron Micrograph ANalysis) is a software package developed at Baylor College of Medicine to perform single particle reconstructions. It examines the average properties of a very large number of molecules to determine the 3 dimensional structure of a molecule from thousands to hundreds of thousands of noisy images of individual molecules at subnanometer resolutions. The diagram of the overall experiment is as the following.  

While the initial 3D model is generated with human interaction, the refinement from a preliminary 3D model to the final model is fully automated. It is the most computationally intensive part of EMAN and the project requires up to hundreds of PFlops which can be benefit from Grid.