M. Boleininger S. L. Dudarev D. R. Mason E. Martínez
We derive a simple analytical line integral expression for the relaxation volume tensor of an arbitrary interconnected dislocation network. This quantity determines the magnitude of dislocation contribution to the dimensional changes and volumetric swelling of a material, and highlights the fundamental dual role of dislocations as sources of intern…
Preprint PublishedL. Reali M.R. Gilbert M. Boleininger S.L. Dudarev
Neutrons interacting with atomic nuclei in most of the materials included in the current fusion reactor designs—notably tungsten, ferritic and stainless steels, copper alloys—generate a γ-photon flux that is comparable in magnitude and e…
Preprint PublishedPui-Wai Ma Daniel R. Mason Steven Van Boxel Sergei L. Dudarev
We simulate effects of irradiation on nanocrystalline tungsten in the athermal high dose limit using the creation-relaxation algorithm, where microstructural evolution is driven not by thermally activated diffusion, but by fluctuating stresses resulting from the production and relaxation of defects. Over the entire interval of radiation exposure sp…
Preprint PublishedLuca Stefanescu Max Boleininger Pui-Wai Ma
We investigated the athermal irradiation-induced swelling and creep in iron subjecting to the application of external uniaxial stress. We studied this through atomic scale simulations using the creation-relaxation algorithm. We also calculated the defect relaxation volume density tensors (or eigenstrain) as a function of external uniaxial stress. B…
Preprint PublishedVignesh Gopakumar Stanislas Pamela Lorenzo Zanisi
Classical sequential models employed in time-series prediction rely on learning the mappings from the past to the future instances by way of a hidden state. The Hidden states characterise the historical information and encode the required temporal dependencies. However, most existing sequential models operate within finite-dimensional Euclidean spa…
PreprintA. Piccione J.W. Berkery S.A. Sabbagh Y. Andreopoulos
One of the biggest challenges to achieve the goal of producing fusion energy in tokamak devices is the necessity of avoiding disruptions of the plasma current due to instabilities. The Disruption Event Characterization and Forecasting (DECAF) framework has been developed in this purpose, integrating physics models of many causal events that can …
PreprintPui-Wai Ma T.-H. Hubert Chan
We have devised a new type of feedforward neural network. It is equivariant with respect to unitary operators $U(n)$. The input and output can be vectors in $\\mathbb{C}^n$ with arbitrary dimension~$n$. No convolution layer is required in our implementation, and we also avoid errors due to truncated higher order terms in Fourier-like transformat…
Preprint PublishedK. Pentland M. Tamborrino T. J. Sullivan J. Buchanan L. C. Appel
Sequential numerical methods for integrating initial value problems (IVPs) can be prohibitively expensive when high numerical accuracy is required over the entire interval of integration. One remedy is to integrate in a parallel fashion, “predicting” the solution serially using a cheap (coarse) solver and “correcting” these values using an …
Preprint PublishedS. H. Ward R. Akers S. D. Pinches A. Loarte R. G. L. Vann M. A. Van Zeeland L. Li Y. Liu A. Polevoi
The LOCUST GPU code has been applied to study the fast-ion transport caused by resonant magnetic perturbations in the high-performance Q = 10 ITER baseline scenario. The computational speed of the code is used calculate the impact of the ITER ELM-control-coil system on neutral beam heating efficiency, as well as producing detailed predictions o…
Preprint Published