Common Aero Vehicle Autonomous Reentry Trajectory Optimization Satisfying Waypoint and No-Fly Zone Constraints

To support the Global Strike mission, an autonomous trajectory optimization technique is presented to minimize the flight time, satisfy terminal and intermediate constraints, and remain within the specified vehicle heating and control limitations. Waypoints are specified for reconnaissance or multiple payload deployments and no-fly zones are specified for geopolitical restrictions or threat avoidance. The Hypersonic Cruise Vehicle (HCV) is used as a simplified two-dimensional platform to compare multiple solution techniques. The solution techniques include a unique geometric approach, an analytical dynamic optimization technique, and a numerical approach. This numerical technique is a direct solution method involving pseudospectral methods and nonlinear programming to converge to the optimal solution. The Common Aero Vehicle (CAV) is used as the test platform for the full three-dimensional reentry trajectory optimization problem. The culmination of this research is the verification of the optimality of this proposed numerical technique, as shown for both the two-dimensional and three-dimensional models. Lastly, user implementation strategies are presented to improve accuracy and enhance solution convergence

Building block libraries and structural considerations in the self-assembly of polyoxometalate and polyoxothiometalate systems

Inorganic metal-oxide clusters form a class of compounds that are unique in their topological and electronic versatility and are becoming increasingly more important in a variety of applications. Namely, Polyoxometalates (POMs) have shown an unmatched range of physical properties and the ability to form structures that can bridge several length scales. The formation of these molecular clusters is often ambiguous and is governed by self-assembly processes that limit our ability to rationally design such molecules. However, recent years have shown that by considering new building block principles the design and discovery of novel complex clusters is aiding our understanding of this process. Now with current progress in thiometalate chemistry, specifically polyoxothiometalates (POTM), the field of inorganic molecular clusters has further diversified allowing for the targeted development of molecules with specific functionality. This chapter discusses the main differences between POM and POTM systems and how this affects synthetic methodologies and reactivities. We will illustrate how careful structural considerations can lead to the generation of novel building blocks and further deepen our understanding of complex systems