A HIERARCHICAL APPROACH TO CONTROL OF COMPLEX ENERGY AND POWER SYSTEMS FOR AIR VEHICLES: Modern aircraft are highly complex systems. This talk will present a particular hierarchical approach to energy and power flow in air vehicles that accommodates multiple power modes. These modes include thermal, fluid, electrical, or mechanical since these are all available in larger aircraft. In particular, with the current drive towards increased electrification, the management of power onboard aircraft has become an enabler or a bottleneck depending on the point of view. A key challenge in working across various modes of power flow is the widely varying time scales. The hierarchy allows for systems operating on different time scales to be coordinated in a controllable manner. It also allows for different dynamic decision making tools to be used at different levels of the hierarchy based on the needs of the physical systems under control. Additional advantages include the modularity and scalability inherent in the hierarchy. Additional modules can be added or removed without changing the basic approach. In addition to the hierarchical control, a particularly useful graph-based approach will be introduced for the purpose of modeling the system interactions. The graph approach, like the hierarchy, has benefits of modularity and scalability along with being an efficient framework for representing systems of different time scales. Recent results will be presented representing both generic interconnected complex systems as well as specific examples and resulting benefits.