Eumelanin is regarded to be an attractive candidate material for biomedical applications. Despite many theoretical studies exploring the structure of eumelanin, an exact mapping of the energetic landscape of the very large phase space of eumelanin is still elusive. In this work, we implement a piecewise Ising Model to predict formation enthalpies of Eumelanin single and double tetramers, and demonstrate its superior predictive and generalizable capabilities. We believe this model will prove very useful in theoretically characterizing the many unique properties attributed to its disorder. The modular nature of the predictive Ising model built up in this work is well-suited for analysis and characterization of a larger phase space of eumelanin polymers, including hexamers and octomers, as well as larger stacked structures, such as potential triple and quadruple eumelanin tetramers. Absorbance data can be incorporated with population-wide predictions of polymer abundance to produce weighted-average predictions of broadband absorbance of bulk eumelanin.
We present a DFT study utilizing the Hubbard U correction to probe structural and magnetic disorder in NaO2, primary discharge product of Na-O2 batteries. We show that NaO2 exhibits a large degree of rotational and magnetic disorder; a 3-body Ising Model is necessary to capture the subtle interplay of this disorder. MC simulations demonstrate that energetically favorable, FM phases near room temperature consist of alternating bands of orthogonally-oriented O2 dimers. We find that bulk structures are insulating, with a subset of FM structures showing a moderate gap (< 2 eV) in one spin channel.
<div class="section abstract"><div class="htmlview paragraph">A state-of-the-art review of the technical meaning and application of the term ‘maneuver’, used by the U.S. Army and ground vehicle engineering communities, was performed with regard to various military activities, including modeling and simulation (M&S), to focus on the value and applicability of the term to military vehicle dynamics. As shown, U.S. military doctrine has built through history and experience a unique concept of maneuver-in-general and its application in U.S. Army unified land operations. Yet, the term ‘maneuver’ needs further technical categorization and characterization for the purpose of dynamics of military unmanned ground vehicles (UGVs) and vehicle design for maneuver. While the NHTSA and SAE standards and definitions provide solid foundations for M&S of cars and trucks to enhance the safety of those vehicles (manned and autonomous), occupants, and pedestrians on roads, the standards cannot address all needs of military vehicles in maneuver. Military UGVs are designed to operate in hyper-dynamic battlefield and tactical conditions on severe terrains where manned systems cannot operate. These operational conditions require a different approach to modeling, simulation, and real-time UGV-self-assessment of its dynamic behavior to be technically capable to fulfill autonomous missions and tasks for the sake of the safety of warfighters and the UGV itself. In the paper, a technical definition for a military vehicle maneuver is presented with the purpose of encompassing vehicle agile movements with extended safety due to controllable instability and also unsafe movements on a need basis. Sub-element definitions of a vehicle maneuver and new ideation of agile movement is proposed to narrow the scope to vehicle military tasks in austere environments. Along with formulation, a graphical interpretation is provided to illustrate advantages of the proposed approach for planning UGV motion using geometric and kinematics characteristics. The contextual application is shown in an operation study to illustrate where the terms can improve M&S.</div></div>
A vehicle’s dynamic factor characterizes the potential that can be created by the powertrain that may be utilized to overcome the rolling resistance, grade resistance, and accelerate the vehicle. The dynamic factor is commonly given as a function of the vehicle's theoretical velocity and computed using the powertrain characteristics without taking into account the effect of the driveline configuration which can impact the tire slippages and vehicle’s actual velocity. The velocity reduction due to tire slip can considerably impact the vehicle speed for off-road vehicles operating with large traction requirements. In this paper, a new approach to interpretation of the dynamic factor is presented which is based on the vehicle's actual velocity and driveline characteristics. The computation of the actual velocity accounts for the individual tire slippages of vehicles with multiple driving axles, which is influenced by the ground condition and power splitting characteristics of the driveline. A comparison of the conventional and proposed approach is given for a 4x4 off-road vehicle. A set of factors for vehicle design are proposed based on integral qualities of the ideal and actual dynamic factor to characterize the combined influence of the transmission and driveline system to utilize the engine power for vehicle acceleration performance.
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