Distributed State Machine Supervision for Long-baseline Gravitational-wave Detectors

The Laser Interferometer Gravitational-wave Observatory (LIGO) consists of two identical yet independent, widely-separated, long-baseline gravitational-wave detectors. Each Advanced LIGO detector consists of complex optical-mechanical systems isolated from the ground by multiple layers of active seismic isolation, all controlled by hundreds of fast, digital, feedback control systems. This article describes a novel state machine-based automation platform developed to handle the automation and supervisory control challenges of these detectors. The platform, called \textit{Guardian}, consists of distributed, independent, state machine automaton nodes organized hierarchically for full detector control. User code is written in standard Python and the platform is designed to facilitate the fast-paced development process associated with commissioning the complicated Advanced LIGO instruments. While developed specifically for the Advanced LIGO detectors, Guardian is a generic state machine automation platform that is useful for experimental control at all levels, from simple table-top setups to large-scale multi-million dollar facilities.Comment: Version 2: 11 pages, 9 figures. Submitted to Review of Scientific Instrument

Draw like a builder, build like a writer. And the crack is in the detail

As the inevitable building by numbers ensues, London’s Thames Gateway becomes one of many playgrounds for bar charting enthusiasts. Houses measured by the thousands and little clues as to where it is, that ghost in the machine, what they are, the structures of everyday contemporary life, and who's life it is anyway. Fernand Braudel, Georges Perec, Jorge Luis Borges, amongst others, are employed to examine just how Wittgensteins radiators find their ways into Barratts South East catalogue. They supply the container for Dickensian content with Sinclairesque detail, while late Jan Turnovski's epic lunacy will help to once and for all allay widespread popular fears that Wittgenstein 1 and 2 may add up to one-and-a-half, simple as that. Never has the ideal of treating technology involved with building as an intellectual discipline been further removed from any notion of genius, loci or otherwise; housing policy housing, building policy building. Against the backdrop of mass housing and landmark buildings with little space or time for anything in between, five years of studio work with diploma students at the University of Greenwich, Vienna University of Technology and University Innsbruck, concerned themselves with the structural narrative of the Thames Gateway. This paper, as well as the projects presented through it, is a premature attempt at anchoring buildings on the words they are built on, technology on the sentence structure of its description, assembly instructions written in the most specific of dialects. It describes techniques, suggesting an architecture read backwards, sideways, horizontal and in parallel, free associative sequence, thus discussing issues of site, context, detail and conceptual adhesion. It also poses questions: concerning locality, history, ritual, conceptualisation and intellectual detachment. Above all, in view of the sheer relentlessness of commercially driven urban expansion, questions of soul and character, of design sustainability in terms of creating space to accommodate viable structures social, cultural, narrative. Allowing history to continue, creating place worth telling tales about