scholarly journals WISER wavefront propagation simulation code: advances and applications

2020 ◽  
Author(s):  
Michele Manfredda ◽  
Aljosa Hafner ◽  
Simone Gerusina ◽  
Nicola Mahne ◽  
Alberto Simoncig ◽  
...  
Keyword(s):  
Simulation Code ◽  
Wavefront Propagation

Driving Torsion Scans with Wavefront Propagation

2020 ◽  
Author(s):  
Yudong Qiu ◽  
Daniel Smith ◽  
Chaya Stern ◽  
mudong feng ◽  
Lee-Ping Wang
Keyword(s):  
Potential Energy ◽  
Force Field ◽  
Degrees Of Freedom ◽  
Computational Cost ◽  
Initial Guess ◽  
Field Development ◽  
Force Field Development ◽  
Wavefront Propagation ◽  
Open Source Software Package

<div>The parameterization of torsional / dihedral angle potential energy terms is a crucial part of developing molecular mechanics force fields.</div><div>Quantum mechanical (QM) methods are often used to provide samples of the potential energy surface (PES) for fitting the empirical parameters in these force field terms.</div><div>To ensure that the sampled molecular configurations are thermodynamically feasible, constrained QM geometry optimizations are typically carried out, which relax the orthogonal degrees of freedom while fixing the target torsion angle(s) on a grid of values.</div><div>However, the quality of results and computational cost are affected by various factors on a non-trivial PES, such as dependence on the chosen scan direction and the lack of efficient approaches to integrate results started from multiple initial guesses.</div><div>In this paper we propose a systematic and versatile workflow called \textit{TorsionDrive} to generate energy-minimized structures on a grid of torsion constraints by means of a recursive wavefront propagation algorithm, which resolves the deficiencies of conventional scanning approaches and generates higher quality QM data for force field development.</div><div>The capabilities of our method are presented for multi-dimensional scans and multiple initial guess structures, and an integration with the MolSSI QCArchive distributed computing ecosystem is described.</div><div>The method is implemented in an open-source software package that is compatible with many QM software packages and energy minimization codes.</div>

scholarly journals Building the Foundation of Robot Explanation Generation Using Behavior Trees

2021 ◽  
Vol 10 (3) ◽  
pp. 1-31
Author(s):  
Zhao Han ◽  
Daniel Giger ◽  
Jordan Allspaw ◽  
Michael S. Lee ◽  
Henny Admoni ◽  
...  
Keyword(s):  
Autonomous Robots ◽  
Free Form ◽  
Static Structure ◽  
Simulation Code ◽  
Causal Information ◽  
Robot Behavior ◽  
Behavior Trees ◽  
Robot Task ◽  
Task Specification ◽  
Explanation Generation

As autonomous robots continue to be deployed near people, robots need to be able to explain their actions. In this article, we focus on organizing and representing complex tasks in a way that makes them readily explainable. Many actions consist of sub-actions, each of which may have several sub-actions of their own, and the robot must be able to represent these complex actions before it can explain them. To generate explanations for robot behavior, we propose using Behavior Trees (BTs), which are a powerful and rich tool for robot task specification and execution. However, for BTs to be used for robot explanations, their free-form, static structure must be adapted. In this work, we add structure to previously free-form BTs by framing them as a set of semantic sets {goal, subgoals, steps, actions} and subsequently build explanation generation algorithms that answer questions seeking causal information about robot behavior. We make BTs less static with an algorithm that inserts a subgoal that satisfies all dependencies. We evaluate our BTs for robot explanation generation in two domains: a kitting task to assemble a gearbox, and a taxi simulation. Code for the behavior trees (in XML) and all the algorithms is available at github.com/uml-robotics/robot-explanation-BTs.

McChasy2: New Monte Carlo RBS/C simulation code designed for use with large crystalline structures

2021 ◽  
Vol 498 ◽  
pp. 9-14
Author(s):  
Lech Nowicki ◽  
Jacek Jagielski ◽  
Cyprian Mieszczyński ◽  
Kazimierz Skrobas ◽  
Przemysław Jóźwik ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Simulation Code ◽  
Crystalline Structures

scholarly journals Depth-Integrated Two-Phase Modeling of Two Real Cases: A Comparison between r.avaflow and GeoFlow-SPH Codes

2021 ◽  
Vol 11 (12) ◽  
pp. 5751
Author(s):  
Seyed Ali Mousavi Tayebi ◽  
Saeid Moussavi Tayyebi ◽  
Manuel Pastor
Keyword(s):  
Rock Avalanche ◽  
Two Phase ◽  
Simulation Code ◽  
Simulation Tools ◽  
Mesh Free ◽  
Particle Hydrodynamics ◽  
Landslide Evolution ◽  
Smoothed Particle ◽  
Hazard And Risk ◽  
Comparison Of The Results

Due to the growing populations in areas at high risk of natural disasters, hazard and risk assessments of landslides have attracted significant attention from researchers worldwide. In order to assess potential risks and design possible countermeasures, it is necessary to have a better understanding of this phenomenon and its mechanism. As a result, the prediction of landslide evolution using continuum dynamic modeling implemented in advanced simulation tools is becoming more important. We analyzed a depth-integrated, two-phase model implemented in two different sets of code to stimulate rapid landslides, such as debris flows and rock avalanches. The first set of code, r.avaflow, represents a GIS-based computational framework and employs the NOC-TVD numerical scheme. The second set of code, GeoFlow-SPH, is based on the mesh-free numerical method of smoothed particle hydrodynamics (SPH) with the capability of describing pore pressure’s evolution along the vertical distribution of flowing mass. Two real cases of an Acheron rock avalanche and Sham Tseng San Tsuen debris flow were used with the best fit values of geotechnical parameters obtained in the prior modeling to investigate the capabilities of the sets of code. Comparison of the results evidenced that both sets of code were capable of properly reproducing the run-out distance, deposition thickness, and deposition shape in the benchmark exercises. However, the values of maximum propagation velocities and thickness were considerably different, suggesting that using more than one set of simulation code allows us to predict more accurately the possible scenarios and design more effective countermeasures.

Performance evaluation of automaticairdust monitors by means of a simulation code

1991 ◽  
Vol 22 ◽  
pp. S383-S386
Author(s):  
C. Bartolomei ◽  
D. Calef ◽  
U. Delprato ◽  
A. Lagioia ◽  
R. Remetti ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Simulation Code

A Nonlinear Rail Vehicle Dynamics Computer Program SAMS/Rail: Part 1—Theory and Formulations

2009 ◽  
Author(s):  
Khaled E. Zaazaa ◽  
Brian Whitten ◽  
Brian Marquis ◽  
Erik Curtis ◽  
Magdy El-Sibaie ◽  
...  
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Contact Element ◽  
Contact Forces ◽  
Simulation Code ◽  
Vehicle Performance ◽  
Normal Contact ◽  
Advantages And Disadvantages ◽  
High Speed Trains

Accurate prediction of railroad vehicle performance requires detailed formulations of wheel-rail contact models. In the past, most dynamic simulation tools used an offline wheel-rail contact element based on look-up tables that are used by the main simulation solver. Nowadays, the use of an online nonlinear three-dimensional wheel-rail contact element is necessary in order to accurately predict the dynamic performance of high speed trains. Recently, the Federal Railroad Administration, Office of Research and Development has sponsored a project to develop a general multibody simulation code that uses an online nonlinear three-dimensional wheel-rail contact element to predict the contact forces between wheel and rail. In this paper, several nonlinear wheel-rail contact formulations are presented, each using the online three-dimensional approach. The methods presented are divided into two contact approaches. In the first Constraint Approach, the wheel is assumed to remain in contact with the rail. In this approach, the normal contact forces are determined by using the technique of Lagrange multipliers. In the second Elastic Approach, wheel/rail separation and penetration are allowed, and the normal contact forces are determined by using Hertz’s Theory. The advantages and disadvantages of each method are presented in this paper. In addition, this paper discusses future developments and improvements for the multibody system code. Some of these improvements are currently being implemented by the University of Illinois at Chicago (UIC). In the accompanying “Part 2” and “Part 3” to this paper, numerical examples are presented in order to demonstrate the results obtained from this research.

A New Model Towards Thermal Mixing and Stratification in Passive Containment

2013 ◽  
Author(s):  
He Zhang ◽  
Fenglei Niu ◽  
Yu Yu ◽  
Peipei Chen
Keyword(s):  
Heat Transfer ◽  
System Analysis ◽  
Cooling System ◽  
Transfer Problem ◽  
Ambient Fluid ◽  
Simulation Code ◽  
Thermal Mixing ◽  
Lumped Parameter ◽  
Passive Safety System ◽  
Transfer Problems

Thermal mixing and stratification often appears in passive containment cooling system (PCCS), which is an important part of passive safety system. So, it is important to accurately predict the temperature and density distributions both for design optimization and accident analysis. However, current major reactor system analysis codes only provide lumped parameter models which can only get very approximate results. The traditional 2-D or 3-D CFD methods require very long simulation time, and it’s not easy to get result. This paper adopts a new simulation code, which can be used to calculate heat transfer problems in large enclosures. The new code simulates the ambient fluid and jets with different models. For the ambient fluid, it uses a one-dimensional model, which is based on the thermal stratification and derived from three conservation equations. While for different jets, the new code contains several jet models to fully simulate the different break types in containment. Now, the new code can only simulate rectangular enclosures, not the cylinder enclosure. So it is meaningful for us to modify the code to simulate the actual containment, then it can be applied to solve the heat transfer problem in PCCS accurately.

The Expansion Model of Debris Cloud Induced by Oblique Hypervelocity Impact

2012 ◽  
Vol 13 (3-4) ◽  
Author(s):  
Qing-Ming Zhang ◽  
Y. H. Chen ◽  
F. L. Huang ◽  
Z. Z. Gong
Keyword(s):  
Conservation Law ◽  
Mass Conservation ◽  
Hypervelocity Impact ◽  
Polar Coordinates ◽  
Dynamic Evolution ◽  
Nonlinear Integral Equations ◽  
Simulation Code ◽  
Debris Cloud ◽  
Expansion Model ◽  
Energy Conservation Law

AbstractFor describing the dynamic evolution of debris cloud formed in oblique hypervelocity impact, a model (expressed in polar coordinates) for the shape, the velocity distribution and the mass distribution is developed according to the results of experiments and numerical simulation, and parameters of the Model are identified by nonlinear integral equations which are derived from mass conservation law and energy conservation law. Afterwards, the model has been verified by another simulation code.

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