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Graph neural network coarse-grain force field for the molecular crystal RDX

npj Computational Materials 2024年第1期10卷 1060-1070页

作者： Brian H.Lee James P.Larentzos John K.Brennan Alejandro Strachan School of Materials Engineering and Birck Nanotechnology Center Purdue UniversityWest LafayetteLafayetteINUSA U.S.Army Combat Capabilities Development Command(DEVCOM)Army Research Laboratory Aberdeen Proving GroundMDUSA

Condense phase molecular systems organize in wide range of distinct molecular configurations,including amorphous melt and glass as well as crystals often exhibiting polymorphism,that originate from their intricate intra-and intermolecular *** accurate coarse-grain(CG)models for these materials are critical to understand phenomena beyond the reach of all-atom simulations,current models cannot capture the diversity of molecular *** introduce a generally applicable approach to develop CG force fields for molecular crystals combining graph neural networks(GNN)and data from an all-atom simulations and apply it to the high-energy density material *** address the challenge of expanding the training data with relevant configurations via an iterative procedure that performs CG molecular dynamics of processes of interest and reconstructs the atomistic configurations using a pre-trained neural network *** multi-site CG model uses a GNN architecture constructed to satisfy translational invariance and rotational covariance for *** resulting model captures both crystalline and amorphous states for a wide range of temperatures and densities.

关键词： grain neural network

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Stability Analyses of Blunted Conical and Ogival Cylinder Forebodies at an Angle of Attack

Stability Analyses of Blunted Conical and Ogival Cylinder Fo...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Liang, Tony Vasile, Joseph D. SURVICE Engineering Company U.S. Army Combat Capabilities Development Command - Army Research Laboratory Aberdeen Proving Ground MD21005 United States

ISBN: (纸本)9781624107238

Stationary cross flow computational investigations of blunted conical and ogival cylindrical forebodies at 4 degrees angle of attack are presented. Base flow simulations were performed at frees tream Reynolds numbers of Re/m = 15.2 × 106 at Mach 6 to match the conditions of Boeing/AFOSR Mach 6 Quiet Tunnel (BAM6QT) at Purdue University. The geometric variations between the ogive and conical forebodies appears to have an influence on the vortexlines where lines on conical forebodies were more skewed towards the leeward side than on ogival for ebodies. Three nose tip bluntness were studied for each forebody configuration, i.e., rb= 0.05, 0.025 and 0.015, respectively. Geometric variations is shown to have an effect on vortexline trajectories and the growth of stationary crossflow disturbances. A correlation between the strength of the derivatives of base flow mass flux at the inflection point and to N-factor grow this suggested. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Angle of attack

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A Computational Environment for Aircraft Design and Acquisition engineering

A Computational Environment for Aircraft Design and Acquisit...

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AIAA SciTech Forum and Exposition, 2023

作者： Haehnel, Robert Hardin, Deanna Bates, Jordan Christensen, Scott Arnold, Thomas Brown, Marvin Bauer, Andrew Brannon, Quyen Church, Joshua Catlett, Amanda Coumbe, Theresa Cold Regions Research and Engineering Laboratory U.S. Army Combat Capabilities Development Command Moffett Field CA94035 United States Information and Technology Laboratory U.S. Army Combat Capabilities Development Command Moffett Field CA94035 United States Aviation and Missile Command U.S. Army Combat Capabilities Development Command Moffett Field CA94035 United States

ISBN: (数字)9781624106996

ISBN: (纸本)9781624106996

Computational Environment (CE) is a web-based portal designed to simplify running Department of Defense (DoD) modeling and simulation (M&S) tools on the DoD Super Computing Resource Center (DSRC) High Performance Computing (HPC) systems. CE is a portal in which applications (apps) for computational tools are housed. These apps provide a graphical user interface to the M&S tool that simplifies set up, running and reviewing the results of parameter studies. We provide an overview of the recent updates to the CE including the features available in the CE Helios 3.0, Kestrel 1.0 and Galaxy 1.0 apps. These apps are wrappers for the DoD CREATE-AV Helios and Kestrel CFD software and the Galaxy Simulation Builder multi-disciplinary design analysis and optimization software. © 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Graphical user interfaces

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Clutter and Ambiguity Reduction Using 3-Dimensional Side-Looking Synthetic Aperture Radar

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Progress In Electromagnetics research B 2023年 102卷 115-130页

作者： Kelly, Colin D. Dogaru, Traian V. Gallagher, Kyle A. Le, Calvin D. Phelan, Brian R. Narayanan, Ram M. The Department of Electrical Engineering and Computer Science The Pennsylvania State University University Park PA16802 United States The U.S. Army Combat Capabilities Development Command Army Research Laboratory AdelphiMD20783 United States

Advancement in radar component technology has led to a reduction in the size, weight, and power consumption of radar systems. Experimental radar systems can now be integrated onto smaller, maneuverable platforms, such as small unmanned aerial vehicles (sUAVs). Integration onto rotor-based sUAVs enables data collection over novel synthetic apertures which can be optimized for different scenarios. The design, simulation, and experimentation of a light-weight, ultra-wideband synthetic aperture radar (SAR) is presented here that will be used for the detection of obscured surface targets. The approach outlined herein uses 3-dimensional (3-D) imagery to vertically resolve clutter from the target. A vertical-grid aperture is presented which yields vertical resolution. Point spread functions are derived for both linear and vertical-grid apertures. The analytical expressions are verified using simulations. Finally, experimental data is used to form 3-D imagery and demonstrate the importance of vertical resolution in the discrimination between scatterers above the ground, as well as clutter mitigation. © (2023). All Rights Reserved.

关键词： Synthetic aperture radar

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Lightweight Low-Cost Multifunctional Composite for Structure

Lightweight Low-Cost Multifunctional Composite for Structure

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Haynes, Robert A. Luzetsky, Harry R. Phifer, Ellen M. U.S. Army Combat Capabilities Development Command Aviation and Missile Center Fort EustisVA23604 United States Research and Analysis Group SURVICE Engineering Company LLC BelcampMD21017 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

The requirement for improved performance in air vehicles necessitates technological advancements in the materials and structures used in those vehicles to achieve weight savings and improved durability and damage tolerance. Simultaneously, vehicle development programs are demanding reductions in cost and fabrication and assembly time. This article presents work to develop a multifunctional composite material technology that saves weight through incorporating electromagnetic shielding into the laminate, improves durability and damage tolerance through use of thermoplastic composite materials, and reduces cost and manufacturing time through continuous compression molding and automated laser in-situ tape placement fabrication techniques. A comparative analysis is conducted with other widely used aircraft designs to quantify the improvements of the multifunctional composite. A representative section of an aircraft tailcone structure is designed, fabricated, and tested to demonstrate the advancements. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Compression molding

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Correlation of Tiltrotor Aeroelastic Stability Wind Tunnel Test 79

Correlation of Tiltrotor Aeroelastic Stability Wind Tunnel T...

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79th Vertical Flight Society Annual Forum and Technology Display, FORUM 2023

作者： Kang, Hao Kreshock, Andrew R. Thornburgh, Robert P. Floros, Matthew Yeo, Hyeonsoo Shen, Jinwei U. S. Army Combat Capabilities Development Command Army Research Laboratory Langley Research Center HamptonVA United States U. S. Army Combat Capabilities Development Command Aviation & Missile Center Ames Research Center Moffett FieldCA United States Department of Aerospace Engineering and Mechanics University of Alabama TuscaloosaAL United States

ISBN: (纸本)9781713874799

This paper presents a correlation study of detailed finite element modeling with component vibration tests and comprehensive analysis modeling with whirl flutter experimental data for the TiltRotor Aeroelastic Stability Testbed (TRAST). TRAST is a semi-span tiltrotor model system that has been developed to investigate tiltrotor whirl flutter phenomena and to provide experimental data for rotorcraft analysis validations. To ensure that real structures are represented accurately by the comprehensive analysis codes, detailed NASTRAN models using 2D/3D shell and solid elements were developed and refined based on vibration tests of the TRAST components. Details of the component vibration tests and correlation with NASTRAN models are described for the rotor blades, hub, and the wing and pylon assembly. The 2D/3D NASTRAN rotor blade model was simplified to a 1-D model consisting solely of beam and other 1-D elements. Using the components and the properties of the 1-D model, structural models for the comprehensive analyses were developed and validated against the vibration test data. Whirl flutter models were developed by adding aerodynamics to the validated structural models. These models were compared to wind-tunnel experimental data. Two comprehensive rotorcraft analysis codes, CAMRAD II and RCAS, were used for the whirl flutter correlation study. Sensitivity of the TRAST whirl flutter prediction to modeling details is discussed. Copyright © 2023 by the Vertical Flight Society. All rights reserved.

关键词： Wind tunnels

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OPTIMIZING PERFORMANCE OF COMPACT HYPERVELOCITY ELECTROTHERMAL GUNS: ELECTRODE COMPOSITION AND BORE DIAMETER 16

OPTIMIZING PERFORMANCE OF COMPACT HYPERVELOCITY ELECTROTHERM...

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16th Hypervelocity Impact Symposium, HVIS 2022

作者： Wilmer, Brian L. Casey Uhlig, W. Berning, Paul R. Coppinger, Matthew J. SURVICE Engineering BelcampMD United States U.S. Army Combat Capabilities Development Command Army Research Laboratory Aberdeen Proving GroundMD United States

ISBN: (纸本)9780791887424

A benchtop electrothermal gun capable of launching mm-sized objects has achieved muzzle velocities ranging from 1.0 to over 6 km/s. Experiments and simulations have been performed to elucidate the key parameters which drive overall performance. Smaller bore diameters with smaller, lower mass projectiles resulted in the largest velocity gains while larger caliber barrels produced higher efficiencies. © 2022 by ASME

关键词： Electric heating

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Bi-Fidelity Neural Network Model for Multi-fuel Capable Internal Combustion Engines

Bi-Fidelity Neural Network Model for Multi-fuel Capable Inte...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Pavalavanni, Pradeep Kumar Narayanan, Sai Ranjeet Sun, Zongxuan Yang, Suo Kim, Kenneth S. Kweon, Chol-Bum M. Department of Mechanical Engineering University of Minnesota - Twin Cities MinneapolisMN55455 United States U.S. Army Combat Capabilities Development Command Army Research Laboratory Aberdeen Proving GroundMD21005 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

Energy Assisted Compression Ignition (EACI) has garnered significant attention in recent years due to its potential applications in aviation propulsion. To enhance combustion and facilitate ignition with low cetane number (CN) jet fuels, a ceramic-based glow plug is utilized as an ignition assistant (IA). Control systems are essential for internal combustion (IC) engines to optimize performance, and ensure durability. They manage various parameters like fuel injection (timing, duration, and amount), ignition timing, and after-treatment systems, making the engine efficient, responsive, and environmentally friendly. A reliable engine control system requires a substantial amount of pressure-crank-angle signals spread across a wide range of operating conditions to effectively train the controller software. For engines operating under a wide range of conditions and control parameters, traditional data collection through experimental methods is both time-consuming and expensive, especially under challenging conditions, such as low CNs. Computational Fluid Dynamics (CFD) can be supplemented to the experimental data. However, the CFD simulation time to generate the wide range of data points for the control systems requires a huge number of CPU hours. In this study, we propose a bi-fidelity regression problem, where we integrate the high-fidelity, expensive experimental data with "low-fidelity", cost-effective CFD data. We employed an artificial neural network (ANN) based methodology for multi-fidelity regression, utilizing two separate ANNs for each level of fidelity. This approach demonstrated effectiveness by achieving physically acceptable error levels in pressure prediction across various operating conditions and engine control parameters, highlighting its potential for efficient and accurate engine control system training in complex IC engine operations. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Glow plugs

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Phenomenological modeling of plasma-assisted methane ignition using plasma energy fraction manifolds

Phenomenological modeling of plasma-assisted methane ignitio...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Noah Johnson, Praise Taneja, Taaresh Sanjeev Sun, Zongxuan Yang, Suo Kim, Kenneth S. Kweon, Chol-Bum M. Department of Mechanical Engineering University of Minnesota - Twin Cities MinneapolisMN55455 United States U.S. Army Combat Capabilities Development Command Army Research Laboratory Aberdeen Proving GroundMD21005 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

The present work advances a phenomenological plasma-assisted combustion model by implementing spatiotemporally varying plasma energy fractions for fast gas heating, vibrational energy excitation, and fast chemical dissociation of gas species. This is achieved through a 2D manifold of plasma energy fractions generated for varying reduced electric fields (E/N) and the thermochemical state of the gas mixture, represented by a progress variable, forming a 2D manifold of energy fractions. The manifold is generated using 0D calculations with a detailed chemical mechanism for plasma-assisted combustion of methane at E/N ranging from 100 to 500 Td and progress variable ranging from 0 (fresh gas mixture) to 1 (burned gas mixture), and is integrated into the phenomenological model. Additionally, a spatiotemporally evolving plasma power density (PPD) obtained from 2D detailed plasma simulations for an air discharge is accommodated in the phenomenological model to describe the evolution of the plasma streamer during discharge. This enhanced model is validated against experiments representing plasma discharge and post-discharge ignition kernel evolution. Specifically, the present model is compared against experimental ultra-fast gas heating and O2 dissociation during plasma discharge, in addition to experimental pressure wave and heated channel radius. The present model is then utilized to investigate ignition kernel evolution for a methane-air discharge across a pin-pin discharge configuration. Specifically, the plasma evolution and the evolution of the post-discharge ignition kernel for a stoichiometric methane-air plasma discharge that utilizes the accommodated spatiotemporal PPD are compared against the results obtained using the original phenomenological model. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Dissociation

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Iso-surface sampler for developing high-dimensional engine controllers using high-fidelity CFD models

Iso-surface sampler for developing high-dimensional engine c...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Narayanan, Sai Ranjeet Govind Raju, Sathya Aswath Sun, Zongxuan Yang, Suo Kim, Kenneth S. Kweon, Chol-Bum M. Department of Mechanical Engineering University of Minnesota Twin Cities MinneapolisMN55455 United States U.S. Army Combat Capabilities Development Command Army Research Laboratory Aberdeen Proving Ground MN21005 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

Developing controllers solely based on experimental testing is an industrious task as it is time-consuming and can be quite expensive. Instead, model-based controller development relies on a model, and hence the controller’s performance relies on the model’s accuracy. In the case of complex physical systems, physics-based high-fidelity models can be developed but cannot be directly used in controllers due to their complexity and computational overhead. Consequently, the use of data-driven models has garnered significant interest as they require minimal knowledge of the underlying physics for model development. However, these models heavily rely on the data based on which they are built. This paper discusses a method for developing reliable controllers by sampling data from high-fidelity computational fluid dynamics (CFD) models developed for internal combustion engine simulations. The developed iso-surface sampler (ISS) methodology samples data at high dimensions automatically in two stages, namely iso-surface generation and infilling. The framework and sampled data was then validated by performing simulations to develop a controller for the combustion phasing of a multi-fuel capable compression ignition engine. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Internal combustion engines

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