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Real Time Markov Decision Processes for Crowd Simulation
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Open Source Tools for High Performance Quasi-Static-Time-Series Simulation Using Parallel Processing.
Abstract not provided.
Time-dependent temperature distribution in slowly cooled molten slag simulated by solidification process and heat transfer model using properties estimated by deep neural network
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CFD Modeling and Simulation in Materials Processing 2016
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Rancor Microworld Simulation Environment for Nuclear Process Control
The Rancor Microworld is a simplified nuclear power plant simulator. It represents the process of an integrated pressurized light water reactor core with a secondary Rankine cycle turbine/generator. The reactor core is governed by simplified core physics. Operators have the ability to raise and lower control rods to change the reactivity and consequently generate more or less electricity. The microworld provides a digital human machine interface for operating and monitoring the plant efficiently to maximize profits within the simulation. The simulation supports multi-unit operations analogous to small modular reactor plants and supports faults on various components within each unit to simulate some common training scenarios such as reactor and turbine trip events. The microworld includes experimental modules to log process parameters and both automated and user control inputs and events, administer situation awareness probes, and interface with eye tracking software.
Sludge Batch 10 Flowsheet Testing with Non-radioactive Simulants
Fourteen Chemical Processing Cell (CPC) simulations were performed with nonradioactive sludge simulants at the Aiken County Technology Laboratory in Aiken, SC. Four of these experiments were performed with Tank 51 sludge simulant. The remaining ten were performed with Tank 40 sludge simulant. The purpose of these experiments was to elucidate the chemistry and characteristics of Sludge Batch (SB) 10 as anticipated in the Defense Waste Processing Facility (DWPF). Experiments were performed at acid stoichiometries between 76% and 138% of the Koopman Minimum Acid requirement (85% - 144% of the Hsu acid requirement) and at REDuction/OXidation (REDOX) targets between 0.1 and 0.3. Testing examined the impact of coupled operations and sludge-only operations during Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) processing at both design basis and nominal boilup rates. This report shares conclusions made as a result of this testing.
Multi-scale modeling and simulation of a novel membrane reactor (MR)/adsorptive reactor (AR) process
Not provided.
Plasma processing of SRF cavities at Jefferson Lab: Experiment results and simulation insight
Plasma processing of superconducting radio frequency (SRF) cavities has been an active research effort at Jefferson Lab (JLab) since 2019, aimed at enhancing cavity performance by removing hydrocarbon contaminants and reducing field emission. In this experiment, processing using argon-oxygen and helium-oxygen gas mixtures to find minimum ignition power at different cavity pressure was investigated. Ongoing simulations are contributing to a better understanding of the plasma surface interactions and the fundamental physics behind the process. These simulations, combined with experimental studies, guide the optimization of key parameters such as gas type, RF power, and pressure to ignite plasma using selected higher-order mode (HOM) frequencies. This paper presents experimental data from argon-oxygen and helium-oxygen gas mixture C75 and C100 cavity plasma ignition studies, as well as simulation results for the C100-type cavity based on the COMSOL model previously applied to the C75 cavity.
Permanganate Oxidation of Defense Waste Processing Facility (DWPF) Recycle Collection Tank (RCT) Simulants Larger Scale Protocol Runs - Chemical Process Cell (CPC) Nominal and Foamover Conditions
Testing to develop a process to oxidize glycolate and other organic species in non-radioactive waste simulants was requested by Savannah River Remediation (SRR). A Task Technical and Quality Assurance Plan (TTQAP) was written to describe the testing requested by SRR in the development of a process to oxidize glycolate and other organic species that are responsible for hydrogen generation from thermolysis. Scoping studies have been completed as requested by a Technical Assistance Request (TAR) to evaluate the feasibility of using sodium permanganate and Fenton's Reagent (iron catalyzed hydrogen peroxide) for destroying glycolate. The results from these scoping studies were summarized in a report. Six phases of tests with simulants have been planned in developing an oxidation flowsheet for the Recycle Collection Tank (RCT), as shown in Table 1. The first three phases have been completed. The first phase comprised of scoping tests of permanganate and Fenton's reagent. The second phase was a matrix of 23 tests completed to inform a down-select decision by SRR and to complete testing needed to understand the influence of various factors in defining the optimum processing conditions for oxidation of organics. From the results of this testing, oxidation by permanganate was chosen over Fenton's reagent with hydrogen peroxide. The third phase of testing was to demonstrate nominal operation of the permanganate oxidation process under protocols similar to those used in the Defense Waste Processing Facility (DWPF).
Tanana River Test Site Model Verification Using the Marine and Hydrokinetic Toolkit (MHKiT)
The marine energy (ME) industry historically lacked a standardized data processing toolkit for common tasks such as data ingestion, quality control, and visualization. The marine and hydrokinetic toolkit (MHKiT) solved this issue by providing a public software deployment (open-source and free) toolkit for the ME industry to store and maintain commonly used functionality for wave, tidal, and river energy. This paper demonstrates an initial model verification study in MHKiT. Using Delft3D, a numerical model of the Tanana River Test Site (TRTS) at Nenana, Alaska was created. Field data from the site was collected using an Acoustic Doppler Current Profiler (ADCP) at the proposed Current Energy Converter (CEC) locations. MHKiT is used to process model simulations from Delft3D and compare them to the transect data from the ADCP measurements at TRTS. The ability to use a single tool to process simulation and field data demonstrates the ease at which the ME industry can obtain results and collaborate across specialties, reducing errors and increasing efficiency.
Parallel Implementation of Nonadditive Gaussian Process Potentials for Monte Carlo Simulations
A strategy is presented to implement Gaussian process potentials in molecular simulations through parallel programming. Attention is focused on the three-body nonadditive energy, though all algorithms extend straightforwardly to the additive energy. The method to distribute pairs and triplets between processes is general to all potentials. Results are presented for a simulation box of argon, including full box and atom displacement calculations, which are relevant to Monte Carlo simulation. Data on speed-up are presented for up to 120 processes across four nodes. A 4-fold speed-up is observed over five processes, extending to 20-fold over 40 processes and 30-fold over 120 processes.
Reduced Order Model Improvement and Integration into Topology Optimization
The purpose of this CRADA was to integrate a reduced order model simulation capability into advanced engineering design capabilities. This work contributed to a substantial reduction in the time required to simulate an additive manufacturing process. Shorter simulation time improves the commercial viability and practical utility of the Sunata software and may lead to wider adoption of additive manufacturing processes.
A phase-field model for quasi-dynamic nucleation, growth, and propagation of rate-and-state faults
Despite its critical role in the study of earthquake processes, numerical simulation of the entire stages of fault rupture remains a formidable task. The main challenges in simulating a fault rupture process include the complex evolution of fault geometry, frictional contact, and off-fault damage over a wide range of spatial and temporal scales. Here, in this paper, we develop a phase-field model for quasi-dynamic fault nucleation, growth, and propagation, which features two standout advantages: (i) it does not require any sophisticated algorithms to represent fault geometry and its evolution; and (ii) it allows for modeling fault nucleation, propagation, and off-fault damage processes with a single formulation. Built on a recently developed phase-field framework for shear fractures with frictional contact, the proposed formulation incorporates rate- and state-dependent friction, radiation damping, and their impacts on fault mechanics and off-fault damage. We show that the numerical results of the phase-field model are consistent with those obtained from well-verified approaches that model the fault as a surface of discontinuity, without suffering from the mesh convergence issue in the existing continuous approaches to fault rupture (e.g., the stress glut method). Further, through numerical examples of fault propagation in various settings, we demonstrate that the phase-field approach may open new opportunities for investigating complex earthquake processes that have remained overly challenging for the existing numerical methods.
Simulations of effects of fiber rigidity on wet press
A previously developed lattice-Boltzmann lattice-spring method is applied to simulate a wet press process. In simulations, multi-individual flexible fibers are settled on a wire screen by the force of gravity, and a fiber network is formed on the top surface of the wire screen. Next, the coordinates and velocities of fluid and fiber solid particles are copied to a computer press simulator composed of two perforated plates. A pressure pulse is imposed at the fluid contact line of the two press plates. Water is squeezed out of the fiber network by the pressure. Finally, during simulations, fiber rigidity, fiber concentrations, and pressure pulses are varied and their effects on water removal and re-wet phenomena are systematically studied.
Mu2e resonant extraction regulation system simulation in delivery ring
Mu2e is an upcoming experiment at Fermilab that relies on the slowly extracted 8 GeV proton beam from the Delivery Ring. The experiment imposes strong requirements on the spill uniformity. To address these requirements, the fast spill regulations system is being developed and commissioned. To inform this development and optimize the system performance we are carrying out the detailed simulations of the regulation process. The simulation includes the effect of six harmonic sextupoles that excite the third-integer resonance and three fast ramping quadrupoles that drive the horizontal tune to 29/3. The components of spill regulation system are designed to mitigate long-term drifts in the beam, ensuring stable operation over extended timescales, as well as addresses rapid variations within single spill. In this study, we review the regulation system design, simulation of the slow regulation, and the fast regulation PID regulation to curtail random variations in the extraction rate that could occur within a single spill.
Modeling Dust Production, Growth, and Destruction in Reionization-era Galaxies with the CROC Simulations: Methods and Parameter Exploration
We introduce a model for the explicit evolution of interstellar dust in a cosmological galaxy formation simulation. We post-process a simulation from the Cosmic Reionization on Computers project, integrating an ordinary differential equation for the evolution of the dust-to-gas ratio along pathlines in the simulation sampled with a tracer particle technique. This model incorporates the effects of dust grain production in asymptotic giant branch star winds and supernovae, grain growth due to the accretion of heavy elements from the gas phase of the interstellar medium, and grain destruction due to thermal sputtering in the high-temperature gas of supernova remnants due to thermal sputtering. A main conclusion of our analysis is the importance of a carefully chosen dust destruction model, for which different reasonable parameterizations can predict very different values at the ∼100 pc resolution of the interstellar medium (ISM) in our simulations. We run this dust model on the single most massive galaxy in a 10 h$^{−1}$ comoving megaparsec box, which attains a stellar mass of ∼2 × 10$^{9}$ M $_{⊙}$ by z = 5. We find that the model is capable of reproducing dust masses and dust-sensitive observable quantities broadly consistent with existing data from high-redshift galaxies. The total dust mass in the simulated galaxy is somewhat sensitive to parameter choices for the dust model, especially the timescale for grain growth due to accretion in the ISM. Consequently, observable quantity observations that can constrain galaxy dust masses at these epochs are potentially useful for placing constraints on dust physics.
The microphysics of the warm-rain and ice crystal processes of precipitation in simulated continental convective storms
Precipitation in clouds can form by either warm-rain or ice crystal processes, referred to as warm and cold formation pathways, respectively. Here, we investigate the warm and cold pathway contributions to surface precipitation in simulated continental convective storms. We analyze three contrasting convective storms that are cold-based, slightly warm-based and very warm-based. We apply tracer-tagging techniques in our aerosol-cloud model to determine simulated microphysical pathways that lead to precipitation. We find cold components of graupel and rain mass were higher than warm components in cold- and slightly warm-based clouds. By contrast, in very warm-based clouds nearly 80% of surface precipitation was formed via warm-rain processes. Lowering of cloud base altitude to levels about 10–20 K warmer switched surface precipitation to being mostly warm, due to enhanced moisture content in the planetary boundary layer and larger cloud droplets aloft intensifying raindrop freezing. Our simulations indicate that warm and cold processes co-exist in any storm and the balance between them is determined by cloud base temperature and solute aerosol conditions.