| 1. |
- Faue, Patrick, et al.
(författare)
-
High-speed X-ray study of process dynamics caused by surface features during continuous-wave laser polishing
- 2023
-
Ingår i: CIRP annals. - : Elsevier. - 0007-8506 .- 1726-0604. ; 72:1, s. 201-204
-
Tidskriftsartikel (refereegranskat)abstract
- During high-speed X-ray imaging of laser surface polishing experiments of specimens of 316L stainless steel at Argonne National Lab's Advanced Photon Source, it was discovered that the induced keyhole changes shape and dimensions while crossing an engineered surface feature without altering process parameters. It was observed that the post-surface feature keyhole was deeper than that of the pre surface feature keyhole. This work reports on the first in-situ observation of the effect of localized surface geometry on underlying melt pool behavior. This has implications for defect formation mechanisms during laser melting processes that rely on melt pool geometry.
|
|
| 2. |
- Volpp, Joerg, et al.
(författare)
-
The surface tension of boiling steel surfaces
- 2024
-
Ingår i: Results in Materials. - : Elsevier. - 2590-048X. ; 22
-
Tidskriftsartikel (refereegranskat)abstract
- Material properties of metals and metal alloys at high temperatures are often unknown, but necessary to understand physical mechanisms for prediction and improvement of high temperature processes, such as laser beam technologies. Surface tension is an elementary property that was measured in this study above the boiling temperature of steel using a laser-induced vapor channel in a steel substrate and the extraction of the vapor channel diameter from in-situ X-ray observations. The measurement principle is based on the pressure balance inside the keyhole, where the recoil pressure from keyhole wall vaporization works against the surface tension pressure from the surrounding melt pool. An increase in surface tension at increasing temperatures above the boiling point was measured against theoretical expectations. In order to create the keyhole shapes measured, the surface tension must increase to counterbalance the increasing recoil pressure.
|
|
| 3. |
- Zhang, Yuhe, et al.
(författare)
-
PhaseGAN : a deep-learning phase-retrieval approach for unpaired datasets
- 2021
-
Ingår i: Optics Express. - 1094-4087. ; 29:13, s. 19593-19604
-
Tidskriftsartikel (refereegranskat)abstract
- Phase retrieval approaches based on deep learning (DL) provide a framework to obtain phase information from an intensity hologram or diffraction pattern in a robust manner and in real-time. However, current DL architectures applied to the phase problem rely on i) paired datasets, i. e., they are only applicable when a satisfactory solution of the phase problem has been found, and ii) the fact that most of them ignore the physics of the imaging process. Here, we present PhaseGAN, a new DL approach based on Generative Adversarial Networks, which allows the use of unpaired datasets and includes the physics of image formation. The performance of our approach is enhanced by including the image formation physics and a novel Fourier loss function, providing phase reconstructions when conventional phase retrieval algorithms fail, such as ultra-fast experiments. Thus, PhaseGAN offers the opportunity to address the phase problem in real-time when no phase reconstructions but good simulations or data from other experiments are available.
|
|
