Representations of Energy Landscapes by Sublevelset Persistent Homology: An Example With n-Alkanes
Authors:
Joshua Mirth,
Yanqin Zhai,
Johnathan Bush,
Enrique G Alvarado,
Howie Jordan,
Mark Heim,
Bala Krishnamoorthy,
Markus Pflaum,
Aurora Clark,
Yang Zhang,
Henry Adams
Abstract:
Encoding the complex features of an energy landscape is a challenging task, and often chemists pursue the most salient features (minima and barriers) along a highly reduced space, i.e. 2- or 3-dimensions. Even though disconnectivity graphs or merge trees summarize the connectivity of the local minima of an energy landscape via the lowest-barrier pathways, there is more information to be gained by…
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Encoding the complex features of an energy landscape is a challenging task, and often chemists pursue the most salient features (minima and barriers) along a highly reduced space, i.e. 2- or 3-dimensions. Even though disconnectivity graphs or merge trees summarize the connectivity of the local minima of an energy landscape via the lowest-barrier pathways, there is more information to be gained by also considering the topology of each connected component at different energy thresholds (or sublevelsets). We propose sublevelset persistent homology as an appropriate tool for this purpose. Our computations on the configuration phase space of n-alkanes from butane to octane allow us to conjecture, and then prove, a complete characterization of the sublevelset persistent homology of the alkane $C_m H_{2m+2}$ potential energy landscapes, for all $m$, and in all homological dimensions. We further compare both the analytical configurational potential energy landscapes and sampled data from molecular dynamics simulation, using the united and all-atom descriptions of the intramolecular interactions. In turn, this supports the application of distance metrics to quantify sampling fidelity and lays the foundation for future work regarding new metrics that quantify differences between the topological features of high-dimensional energy landscapes.
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Submitted 19 March, 2021; v1 submitted 2 November, 2020;
originally announced November 2020.
Gyro-Control of a Solar Sailing Satellite
Authors:
Hendrik Willem Jordaan,
Willem Herman Steyn
Abstract:
Recent successes in the deployment of sails in space have reduced the risk associated with solar sailing missions. The attitude control requirements for a solar sailing mission is low with only slow attitude maneuvers needed to maintain a stable attitude and produce a required solar thrust. Future science missions will require large attitude maneuvers with a fully deployed sail. This article inves…
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Recent successes in the deployment of sails in space have reduced the risk associated with solar sailing missions. The attitude control requirements for a solar sailing mission is low with only slow attitude maneuvers needed to maintain a stable attitude and produce a required solar thrust. Future science missions will require large attitude maneuvers with a fully deployed sail. This article investigates the current options for attitude control on solar sails and proposes a gyro-controlled solar sailing. This concept uses a spinning solar sail to construct a control moment gyroscope capable to produce large torques. Steering laws for performing attitude maneuvers and simulation results are presented which demonstrates the capabilities of such a solution.
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Submitted 29 October, 2019;
originally announced October 2019.