arXiv subjects

Soraya Terrab

Publications and source records attributed to Soraya Terrab.

3 recordsLinked to original sources

arXiv2024

A hybrid SIAC -- data-driven post-processing filter for discontinuities in solutions to numerical PDEs

We present a hybrid filter that is only applied to the approximation at the final time and allows for reducing errors away from a shock as well as near a shock. It is designed for discontinuous Galerkin approximations to PDEs and combines a rigorous moment-based Smoothness-Increasing Accuracy-Conserving (SIAC) filter with a data-driven CNN filter. While SIAC improves accuracy in smooth regions, it fails to reduce the $\mathcal{O}(1)$ errors near discontinuities, particularly in inviscid compressible flows with shocks. Our hybrid SIAC-CNN filter, trained exclusively on top-hat functions, enforces consistency constraints globally and higher-order moment conditions in smooth regions, reducing both $\ell_2$ and $\ell_\infty$ errors near discontinuities and preserving theoretical accuracy in smooth regions. We demonstrate its effectiveness on the Euler equations for the Lax, Sod, and Shu-Osher shock-tube problems.

math.NA↗

arXiv2022

Global Sensitivity Analysis of Plasma Instabilities via Active Subspaces

Active subspace analysis is a useful computational tool to identify and exploit the most important linear combinations in the space of a model's input parameters. These directions depend inherently on a quantity of interest, which can be represented as a function from input parameters to model outputs. As the dynamics of many plasma models are driven by potentially uncertain parameter values, the utilization of active subspaces to perform global sensitivity analysis represents an important tool to understand how certain physical phenomena depend upon fluctuations in the values of these parameters. In the current paper, we construct and implement new computational methods to quantify the induced uncertainty within the growth rate generated by perturbations in a collisionless plasma modeled by the one-dimensional Vlasov-Poisson system near an unstable, spatially-homogeneous equilibrium in the linear regime.

physics.plasm-ph↗

arXiv2016

Ionic liquid-based variable focus electrowetting optics with bandwidths spanning the visible to mid-infrared

Infrared optical materials and devices are important for a wide range of applications in the defense, scientific, and consumer markets. For imaging, spectroscopy, microscopy and persistent surveillance, adaptive optic systems that span the visible to infrared region are particularly useful. We address this need with novel electrowetting lens and prism elements that operate from 400 to 5000 nm. In contrast to conventional electrowetting devices that use polar liquids, limited by high absorption in the infrared region, we present room-temperature ionic liquid-based (RTIL, N-Propyl-Nmethylpyrrolidinium Bis(fluorosulfonyl)imide, Pyr1333a, Solvionic) lens and prism elements with unprecedented spectral bandwidths. Our electrowetting lenses tune over 20 diopters and have been demonstrated at 588, 1550 and 3000 nm wavelengths. Additionally, we have demonstrated prism elements with a steering angle of 0.56° at 1550 nm.

physics.optics↗