LHC Machine Developments in 2011-12

In 2011 and 2012 LHC Machine Development (MD) sessions were performed during dedicated slots of beam time. These MD studies were scheduled and planned well in advance. Study topics reflected the previously agreed priorities, such as further optimizing machine performance, exploring beam parameters beyond design targets, assessing machine limitations, testing new concepts and machine settings, preparing future LHC running in view of the 2013/14 LHC Shutdown (LS1) and the re-commissioning of the LHC at close to nominal beam energy in 2014/15. We describe the planning, preparation, execution, review, and documentation of these LHC beam studies and highlight a few key results.