# Condition-Based Monitoring and Maintenance: State of the Art Review
## 3 University Research Related to CBM  
As people around the world are becoming increasingly more aware of the applications of CBM, they are taking interest in developing new technologies and strategies and are coming up with new management tools related to CBM. Most of this research around the world takes place in universities and defense. In the United States, the Department of Defense (DoD) has invested a large amount in the field of CBM. Their main focus is to meet the warfighter expectation while making every effort to conduct cost-effective sustainment operations. Thus, on 7 November 2007, DoD established a policy for CBM+, which provides an integrated strategy for deployment of enabling technologies, processes, and procedures that focus on a broad range of weapon system sustainment improvements. CBM+ was originally developed as a DoD initiative to provide a focus for a broad variety of maintenance improvements that would benefit both the maintainer and the warfighter [151]. It was established to expand upon condition-based maintenance (CBM) and encompasses other technologies, processes, and procedures that enable improved maintenance and logistics practices. The CBM+ Action Group developed a \"CBM+ DoD Guidebook\" as aninformation reference and tool to assist logistic managers with CBM+ project development, implementation, and execution. Defense Acquisition University, which provides learning and consulting for acquisition programs and projects, provides training on CBM+ business case analysis [152]. The Condition-Based Maintenance plus (CBM+) module provides the learner with an overview and introduction to Depot Maintenance Management and Operations needed in DoD systems [153]. The Applied Research Laboratory at the Pennsylvania State University (ARL Penn State) is using a systems approach for CBM. This is done by using a hierarchical architecture for developing and implementing health assessment systems. Here, in this hierarchy, a system is considered right from the top level to the lowest level of components where the failure originates. This hierarchical architecture consists of six levels: material, element, component, subsystem, system, and plant platform. They have been working in this field since 1994 and have established themselves as the world leader in CBM mechanical systems. Their projects cover various CBM issues from materials to decision support. The Systems and Operations Automation (SOA) Division of the ARL Penn State addresses the emerging fields of condition-based maintenance (CBM) and advanced sensing and control. The division provides valuable research and development efforts to support the U.S. Department of Defense and U.S. industry. It uses a number of specialized tools and facilities focused on condition-based maintenance such as mechanical diagnostic test bed, diesel-enhanced mechanical diagnostic test bed, lubrication system test bench, bearing prognostics test rig, torsional test rig, ball and V-ring test stand, battery prognostics test bench, complex systems monitoring features toolbox, and systems integration and technology transfer (SITT) facility [154]. A lot of research is being done at the University of South Carolina (USC), in which emphasis has been given to collect and warehouse data and formulate requirements for a move towards CBM. Their CBM Research Centre has supported the U.S. Army by conducting research to support a timely and cost-effective aircraft maintenance program. The CBM program at USC combines comprehensive research with a multi-faceted methodology to strive towards continued success by the U.S. Army's aviation division. The CBM test facilities include a full-scale drive train test that stands capable of testing several platforms such as the U.S. Army Apache, Blackhawk, and Chinoco helicopters [155].