Capabilities needed in Information management for a digital built Britain

Network FOuNTAIN is the Network For ONTologies And Information maNagement in Digital Built Britain, a project funded by the Centre for Digital Built Britain. The vision of the Network is for all stakeholders in Digital Built Britain (DBB) to be able to meet their information needs. With the establishment of concepts such as Building Information Modelling and Common Data Environments, built environment design, construction and operation are becoming increasingly information-intensive. The Network undertook five workshop activities between July and December 2018. This paper summarises the proceedings of these workshops, and in particular establishes future capabilities needed to realise the vision of DBB. The first workshop sought to establish the scope of “Information Management”. It was concluded that the capability to gauge Information Management Maturity was needed. The second and third workshops focused on ontologies and reviewed the variety of standards currently available. It was concluded that the capability was needed to establish the appropriate scope of standardisation, and to design or extend existing ontologies in general. The capability was also needed to develop current classification systems, schema and frameworks, Uniclass 2015 in particular, to maximise the potential to share data. The fourth workshop explored system requirements; it identified three modes of consuming information and the corresponding software requirements for each mode. The three modes identified are: Search & Retrieval, Browsing & Expiration and Information Delivery. The fifth and final workshop focused on business models and concluded that the capability was needed to identify and derive business value from Information Management. The paper closes with a research agenda required to deliver those capabilities. Fundamental research is needed to formulate a process of establishing the appropriate scope of standardisation for Information Management at project, organisation and industry levels. This research needs to unfold in the context of emerging related international standards. <br

A Neutron Star Binary Merger Model for GW170817/GRB170817a/SSS17a

The merging neutron star gravitational wave event GW170817 has been observed throughout the entire electromagnetic spectrum from radio waves to $\gamma$-rays. The resulting energetics, variability, and light curves are shown to be consistent with GW170817 originating from the merger of two neutron stars, in all likelihood followed by the prompt gravitational collapse of the massive remnant. The available $\gamma$-ray, X-ray and radio data provide a clear probe for the nature of the relativistic ejecta and the non-thermal processes occurring within, while the ultraviolet, optical and infrared emission are shown to probe material torn during the merger and subsequently heated by the decay of freshly synthesized $r$-process material. The simplest hypothesis that the non-thermal emission is due to a low-luminosity short $\gamma$-ray burst (sGRB) seems to agree with the present data. While low luminosity sGRBs might be common, we show here that the collective prompt and multi-wavelength observations are also consistent with a typical, powerful sGRB seen off-axis. Detailed follow-up observations are thus essential before we can place stringent constraints on the nature of the relativistic ejecta in GW170817.Comment: 9 pages, 5 figures, accepted to ApJ Letter

Electromagnetic Evidence that SSS17a is the Result of a Binary Neutron Star Merger

11 hours after the detection of gravitational wave source GW170817 by the Laser Interferometer Gravitational-Wave Observatory and Virgo Interferometers, an associated optical transient SSS17a was discovered in the galaxy NGC 4993. While the gravitational wave data indicate GW170817 is consistent with the merger of two compact objects, the electromagnetic observations provide independent constraints of the nature of that system. Here we synthesize all optical and near-infrared photometry and spectroscopy of SSS17a collected by the One-Meter Two-Hemisphere collaboration. We find that SSS17a is unlike other known transients. The source is best described by theoretical models of a kilonova consisting of radioactive elements produced by rapid neutron capture (the r-process). We find that SSS17a was the result of a binary neutron star merger, reinforcing the gravitational wave result.Comment: 21 pages, 4 figures, accepted to Scienc

Network FOuNTAIN a CDBB network: For ONTologies and information maNagement in digital built Britain. Final report.

Network FOuNTAIN is the Network For ONTologies And Information maNagement in Digital Built Britain. The Network is supported by the Centre for Digital Built Britain. The vision of the Network is for all stakeholders in Digital Built Britain (DBB) to be able to meet their information needs. With the establishment of concepts such as Building Information Modelling (BIM) and Common Data Environments (CDE), built environment design, construction and operation are becoming increasingly information-intensive. The Network undertook five workshop activities between July and December 2018. This report summarises the proceedings of these workshops, and in particular establishes future capabilities needed to realise the vision of DBB

Jet Formation in 3D GRMHD Simulations of Bondi-Hoyle-Lyttleton Accretion

A black hole (BH) travelling through a uniform, gaseous medium is described by Bondi-Hoyle-Lyttleton (BHL) accretion. If the medium is magnetized, then the black hole can produce relativistic outflows. We performed the first 3D, general-relativistic magnetohydrodynamics simulations of BHL accretion onto rapidly rotating black holes using the code H-AMR, where we mainly varied the strength of a background magnetic field that threads the medium. We found that the ensuing accretion continuously drags to the BH the magnetic flux, which accumulates near the event horizon until it becomes dynamically important. Depending on the strength of the background magnetic field, the BHs can sometimes launch relativistic jets with high enough power to drill out of the inner accretion flow, become bent by the headwind, and escape to large distances. While for stronger background magnetic fields the jets are continuously powered, at weaker field strengths they are intermittent, turning on and off depending on the fluctuating gas and magnetic flux distributions near the event horizon. We find that our jets reach extremely high efficiencies of $\sim100-300\%$, even in the absence of an accretion disk. We also calculated the drag forces exerted by the gas onto to the BH, finding that the presence of magnetic fields causes drag forces to be much less efficient than in unmagnetized BHL accretion, and sometimes become negative, accelerating the BH rather than slowing it down. Our results extend classical BHL accretion to rotating BHs moving through magnetized media and demonstrate that accretion and drag are significantly altered in this environment.Comment: Comments welcome! 16 pages, 8 figures, submitted to Ap

Network FOuNTAIN A CDBB network: For ONTologies and information maNagement in digital built Britain: Final report

Network FOuNTAIN is the Network For ONTologies And Information maNagement in Digital Built Britain. The Network is supported by the Centre for Digital Built Britain. The vision of the Network is for all stakeholders in Digital Built Britain (DBB) to be able to meet their information needs. With the establishment of concepts such as Building Information Modelling (BIM) and Common Data Environments (CDE), built environment design, construction and operation are becoming increasingly information-intensive. The Network undertook five workshop activities between July and December 2018. This report summarises the proceedings of these workshops, and in particular establishes future capabilities needed to realise the vision of DBB