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M. Shaw

Publications and source records attributed to M. Shaw.

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Closing the Loop: Deploying Auto-Generating Digital Twins for Particle Accelerators

The simulation of a physical system in a virtual replica, known as a digital twin, is a useful way to interrogate the system non-invasively, providing the ability to perform predictive maintenance and surveillance, and to investigate potential novel configurations without perturbing the system. This article presents the implementation of an auto-generating digital twin architecture for particle accelerators: a virtual control system is generated to mirror the physical accelerator hardware, and used to update a simulation model which then feeds back the results into virtual diagnostics. All of the information about the accelerator lattice is cascaded down from a ground source of truth, removing any ambiguity about the naming of parameters between the simulation model and the virtual hardware. This design is modular and extensible, allowing researchers from different institutions to use their own models (for example, a machine learning model) and accelerator lattices while maintaining the overall structural coherence of the digital twin. This architecture has been tested for three accelerator facilities \textendash~CLARA, the ISIS injector, and the proposed UK XFEL \textendash~and aims to provide the foundation for a collaborative community effort in the development of shared technology towards a generic digital twin solution.

physics.acc-ph

Nuclear bars and blue nuclei within barred spiral galaxies

Multicolour near IR photometry for a sample of 32 large barred spiral galaxies is presented. By applying ellipse fitting techniques, we identify significant isophote twists with respect to the primary bar axis in the nuclear regions of $\sim$70 \%\ of the sample. These twists are identified in galaxies as late as SBbc and are clearly distinguishable from spiral arm morphology. At most seven of the galaxies with isophote twists are inferred to possess secondary (nuclear) bars, the axis ratios of which appear to correlate with morphological type. The remainder may result from triaxial bulges, or from oblate bulges misaligned with the primary bar. The near IR colour distributions in these data show evidence for (red) circumnuclear star forming rings in 4 galaxies. The majority of the sample (19) also possess striking blue nuclear regions, bluer than typical old stellar populations by $\sim$0.3 mag. in (J--H) and $\sim$0.23 mag. in (H--K). Such blue colours do not appear to correlate with the presence of nuclear rings or pseudo--rings, nor with the activity of the host galaxy (as determined from emission--line spectroscopic characteristics). Several mechanisms to explain this blue colour are considered.

astro-ph