Validation of the U.S. Army Research Laboratory's Gun Dynamics Simulation Codes for Prototype Kinetic Energy

2003 ◽  
Author(s):  
James F. Newill ◽  
Bernard J. Guidos ◽  
Carl D. Livecchia
Keyword(s):  
Kinetic Energy ◽  
Dynamics Simulation ◽  
The U.S ◽  
Simulation Codes

Impact of Resolution and Design on the U.S. Navy Global Ensemble Performance in the Tropics

2011 ◽  
Vol 139 (7) ◽  
pp. 2145-2155 ◽  
Author(s):  
Carolyn A. Reynolds ◽  
Justin G. McLay ◽  
James S. Goerss ◽  
Efren A. Serra ◽  
Daniel Hodyss ◽  
...  
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Kinetic Energy ◽  
Ensemble Prediction ◽  
Cyclone Track ◽  
Tropical Cyclone Track ◽  
Ensemble Performance ◽  
Ensemble Mean ◽  
The Tropics ◽  
The U.S

Abstract The performance of the U.S. Navy global atmospheric ensemble prediction system is examined with a focus on tropical winds and tropical cyclone tracks. Ensembles are run at a triangular truncation of T119, T159, and T239, with 33, 17, and 9 ensemble members, respectively, to evaluate the impact of resolution versus the number of ensemble member tradeoffs on ensemble performance. Results indicate that the T159 and T239 ensemble mean tropical cyclone track errors are significantly smaller than those of the T119 ensemble out to 4 days. For ensemble forecasts of upper- and lower-tropospheric tropical winds, increasing resolution has only a small impact on ensemble mean root-mean-square error for wind speed, but does improve Brier scores for 10-m wind speed at the 5 m s−1 threshold. In addition to the resolution tests, modifications to the ensemble transform initial perturbation methodology and inclusion of stochastic kinetic energy backscatter are also evaluated. Stochastic kinetic energy backscatter substantially increases the ensemble spread and improves Brier scores in the tropics, but for the most part does not significantly reduce ensemble mean tropical cyclone track error.

Molecular Dynamics Simulation of Fullerene Cluster Ion Impact

1997 ◽  
Vol 504 ◽  
Author(s):  
Takaaki Aoki ◽  
Toshio Seki ◽  
Masahiro Tanomura ◽  
Jiro Matsuo ◽  
Zinetulla Insepov ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Kinetic Energy ◽  
Carbon Cluster ◽  
Dynamics Simulation ◽  
Multiple Collision ◽  
Sapphire Substrates ◽  
Cluster Ion ◽  
Ion Impact ◽  
Dynamics Simulations ◽  
Cascade Damage

ABSTRACTIn order to interpret the projection range and to reveal the mechanism of damage formation by cluster ion impact, molecular dynamics simulations of a fullerene carbon cluster (C60) impacting on diamond (001) surfaces were performed. When the kinetic energy of C60 is as low as 200eV/atom, C60 implants into the substrate deeper than a monomer ion with the same energy per atom because of the clearing-way effect. The kinetic energy of the cluster disperses isotropically because of the multiple-collision effect, and then a large hemispherical damage region is formed. When the energy of the cluster is as high as 2keV/atom, the cluster dissociates in the substrate, and then cascade damage is formed like in a case of a monomer ion impact. The projection range of incident atoms becomes similar to that of the monomer with the same energy per atom. However, the number of displacements of C60 is larger than the summation of 60 monomer carbons. The displacement yield of fullerene is 4 to 7 times higher than that of monomer carbon. This result agrees with the measurement of the displacements made on sapphire substrates with C60 and C2 irradiation.

MOLECULAR-DYNAMICS SIMULATION OF RADIATION DAMAGE ON COPPER CLUSTERS

2000 ◽  
Vol 11 (05) ◽  
pp. 1025-1032
Author(s):  
ŞAKIR ERKOÇ
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Kinetic Energy ◽  
Potential Energy ◽  
Radiation Damage ◽  
Potential Energy Function ◽  
Dynamics Simulation ◽  
External Radiation ◽  
Empirical Potential ◽  
Copper Clusters

The effect of radiation damage on copper clusters has been investigated by performing molecular-dynamics simulation using empirical potential energy function for interaction between copper atoms. The external radiation is modeled by giving extra kinetic energy in the range of 5–50 eV to initially chosen atom in the cluster. It has been found that the atom having extra kinetic energy dissociates independently from the amount of given energy in the studied range.

Modeling Energy Portfolio Scoring

2016 ◽  
pp. 203-226
Author(s):  
Rafael Diaz ◽  
Joshua G. Behr ◽  
Rafael Landaeta ◽  
Francesco Longo ◽  
Letizia Nicoletti
Keyword(s):  
Renewable Energy ◽  
Policy Making ◽  
Production Method ◽  
Economic Benefits ◽  
Dynamics Simulation ◽  
Electricity Production ◽  
Hampton Roads ◽  
Support Policy ◽  
The Impact ◽  
The U.S

U.S. regions are expected to follow the national trend towards investment in renewable energy as part of their electricity portfolio. The progress of energy portfolios that typically involves traditional methods, such as centralized nuclear and coal-fired generation, and towards cleaner- and renewable-source generation will impact economic growth and public health. Renewable electricity production must strike a balance among cost, reliability, and compatibility. The economic and health benefits obtained from developing an efficient energy portfolio make renewable energy alternatives an important consideration for regions endowed with natural resources. A portfolio mix of production method that considers the economic benefits while limiting adverse health and environmental impacts is attractive. This research proposes a System Dynamics simulation framework to support policy-making efforts in assessing the impact of energy portfolios. The authors demonstrate the utility of the framework by means of analyzing data that pertain to the U.S. Hampton Roads - Peninsula Region.

scholarly journals Sensitive Five-Fold Local Symmetry to Kinetic Energy of Depositing Atoms in Cu-Zr Thin Film Growth

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2548 ◽  
Author(s):  
Lu Xie ◽  
Haojie An ◽  
Qing Peng ◽  
Qin Qin ◽  
Yong Zhang
Keyword(s):  
Kinetic Energy ◽  
Metallic Glass ◽  
Material Design ◽  
Local Symmetry ◽  
Growth Conditions ◽  
Glass Forming Ability ◽  
Dynamics Simulation ◽  
Index Method ◽  
Glass Forming ◽  
Glass Films

We have investigated the glass formation ability of Cu-Zr alloy by molecular dynamics simulation of the deposition process. The atomistic structures of ZrxCu100−x metallic glass films have been systematically examined under the growth conditions of hypereutectic-eutectic, near-eutectic, and hypoeutectic regions by the radial distribution function and simulated X-ray diffraction. The structure analysis using Voronoi polyhedron index method demonstrates the variations of short-range order and five-fold local symmetry in ZrxCu100−x metallic glass films with respect to the growth conditions. We manifest that the five-fold local symmetry is sensitive to the kinetic energy of the depositing atoms. There is positive correlation between the degree of five-fold local symmetry and glass forming ability. Our results suggest that sputtering conditions greatly affect the local atomic structures and consequential properties. The glass forming ability could be scaled by the degree of five-fold local symmetry. Our study might be useful in optimizing sputtering conditions in real experiments, as well as promising implications in material design of advanced glassy materials.

Adjustments in Tornado Counts, F-Scale Intensity, and Path Width for Assessing Significant Tornado Destruction

2014 ◽  
Vol 53 (6) ◽  
pp. 1494-1505 ◽  
Author(s):  
Ernest Agee ◽  
Samuel Childs
Keyword(s):  
Kinetic Energy ◽  
Doppler Radar ◽  
Lower Threshold ◽  
Maximum Width ◽  
Wind Speeds ◽  
Mean Width ◽  
Increasing Trend ◽  
Highly Correlated ◽  
The U.S ◽  
Mean Kinetic Energy

AbstractThe U.S. tornado record is subject to inhomogeneities that are due to inconsistent practices in counting tornadoes, assessing their damage, and measuring pathlength and path width. Efforts to improve the modern tornado record (1950–2012) have focused on the following: 1) the rationale for removing the years 1950–52, 2) identification of inconsistencies in F0, F1, and F2 counts based on implementation of the Fujita scale (F scale) and Doppler radar, 3) overestimation of backward-extrapolated F-scale intensity, and 4) a change in path-width reporting from mean width (1953–94) to maximum width (1995–2012). Unique adjustments to these inconsistencies are made by analyzing trends in tornado counts, comparing with previous studies, and making an upward adjustment of tornadoes classified by mean width to coincide with those classified by maximum width. Such refinements offer a more homogeneous tornado record and provide the opportunity to better evaluate climatological trends in significant (F/EF2–F/EF5) tornado activity. The median EF-scale (enhanced Fujita scale) wind speeds Vmed have been adopted for all significant tornadoes from 1953 to 2012, including an adjustment for overestimated intensities from 1953 to 1973. These values are used to calculate annual mean kinetic energy, which shows no apparent trend. The annual mean maximum path width from 1953 to 2012 (adjusted upward from 1953 to 1994 to obtain a common lower threshold), however, displays an increasing trend. Also, the EF-scale median wind speeds are highly correlated with . The quantity (Vmed × PWmax)2 is proposed as a tornado destruction index, and, when calculated as an annual cumulative value, the three largest years are 2007, 2008, and 2011.

scholarly journals Dynamics of liquid argon flow around carbon nanotube

2020 ◽  
Author(s):  
Masoud Arabghahestani ◽  
Mohammadamin Sheikhshahrokhdehkordi ◽  
Nelson K. Akafuah
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Kinetic Energy ◽  
Flow Velocity ◽  
Drag Force ◽  
Liquid Argon ◽  
The Body ◽  
Dynamics Simulation ◽  
Computational Domain ◽  
Argon Flow

In this work non-equilibrium molecular dynamics (MD) simulations were performed to investigate the liquid argon flow passing a stationary carbon nanotube and to estimate kinetic energy of the flow and flow forces exerted on the nanotube. Effects of different factors were also investigated. CFD simulations of flow around a circular cylinder were also performed to compare the results with those of MD around the carbon nanotube. In molecular dynamics simulation, the fluid forces on the body are calculated directly from the summation of the molecular forces exerted on solid atoms by fluid atoms. In this work, this method is used to investigate the effects of different flow parameters such as flow velocity, flow temperature on the flow behavior over the carbon nanotube, atom positioning around the nanotube and forces exerted on it. The simulation is 3D, and the computational domain consists of a maximum of 33,700 liquid argon atoms as the fluid and 240 atoms of carbon which represent the solid nanotube. A single-walled carbon nanotube is simulated as a rigid body of fixed carbon atoms, and both argon-argon and argon-carbon interactions are modeled by the standard Lennard-Jonnes potential function. Flow is driven by rescaling fluid particles velocities at the inlet region with a length of 3% of the domain length in that direction every 50-time steps. Based on the information given, a parallel code was developed, and investigations have been conducted using this code. Results show that among all the parameters which were investigated in this paper, the flow velocity has the most significant effects on the exerted forces and kinetic energy on the carbon nanotube and the drag force is increased with an increment of the flow inlet velocity in all cases. Lift fluctuates around zero in all cases of the stationary carbon nanotube. Inlet flow velocities and temperatures have also changed atoms positioning in the vicinity of the nanotube and so atomic density in the nearby bins which is used to further clarify the difference in the drag force.

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