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Reliable Dynamic Causality Analysis for Efficient Prescriptive Maintenance of Degraded Industrial Equipment
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Multi-omics fusion network for prediction of early recurrence in colorectal liver metastases
No full textThe behavior of sulfur regolith concrete under micrometeoroid impacts for lunar surface structures
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Enhancing the computational performance of granular flow simulations in DEM and CFD-DEM with adaptive sparse contacts (ASC)
No full textABSTRACT: The Discrete Element Method (DEM) is a popular numerical method to predict granular flows. However, systems containing a considerable number of particles entail significant computational costs. In this work, we present the Adaptive Sparse Contacts (ASC), designed to enhance the computational efficiency of DEM simulations, particularly for particles in a quasi-static state, through granular temperature evaluation. An extension to CFD-DEM with an advection term that allows the fluid-driven particle motion is also presented. Results obtained with a rectangular hopper case show the adaptability of the algorithm with respect to the variation in particulate flow dynamics with a speedup up to 2.4x. The sensitivity of the method to the granular temperature threshold is assessed using a dam break case. Evaluation of the ASC on fluidized bed and pneumatic conveying cases shows suitability for capturing dense particle-laden flows in CFD-DEM simulations
Toward highly accurate multigroup coupled photon-electron-positron cross-sections for the Boltzmann Fokker-Planck Equation
Full text linkABSTRACT: For many contemporary applications, ionizing radiation transport plays a pivotal role, requiring an accurate assessment of its impact on the exposed environment. While Monte Carlo simulations are widely considered the gold standard for accurate general-purpose coupled transport of photons, electrons and positrons in matter, discrete ordinates algorithms provide a viable alternative. This work consolidates cross-section models for coupled photon-electron-positron transport and provides the methodology to generate the data required by the multigroup Boltzmann Fokker-Planck transport equation and by energy and charge deposition formulas. It includes elastic, collisional and radiative inelastic interactions of leptons, annihilation of positrons, Compton scattering, Rayleigh scattering, photoelectric effect, pair production as well as fluorescence and Auger electron production from relaxation cascades following ionization. Comparative analyses of energy deposition in water, aluminum, and gold are conducted for incident beams of 1 MeV, 10 MeV, and 100 MeV electrons and photons, and juxtaposed against Monte Carlo reference calculations. While disparities of a few percent are typical, higher deviation can be observed due to discretization or physical model limitations. Energy spectrums per particle type at varying depths in the medium are also contrasted with Monte Carlo calculations to discern limitations in the current implementation and to propose potential avenues for enhancing the presented models. Energy and charge deposition calculations are also compared to experimental measurements. The cross-section production and transport algorithms are implemented in an open-source Julia package, Radiant.jl
