192 research outputs found
Proceedings of the 26th International Symposium on Theoretical Aspects of Computer Science (STACS'09)
The Symposium on Theoretical Aspects of Computer Science (STACS) is held alternately in France and in Germany. The conference of February 26-28, 2009, held in Freiburg, is the 26th in this series. Previous meetings took place in Paris (1984), Saarbr¨ucken (1985), Orsay (1986), Passau (1987), Bordeaux (1988), Paderborn (1989), Rouen (1990), Hamburg (1991), Cachan (1992), W¨urzburg (1993), Caen (1994), M¨unchen (1995), Grenoble (1996), L¨ubeck (1997), Paris (1998), Trier (1999), Lille (2000), Dresden (2001), Antibes (2002), Berlin (2003), Montpellier (2004), Stuttgart (2005), Marseille (2006), Aachen (2007), and Bordeaux (2008). ..
A Multi-Scale Flexible Framework for Urban Modelling
Ph. D. ThesisThe configuration of urban areas, and of infrastructures which serve them is central to
managing the urbanisation process. Integrated assessment frameworks aim to inform
decisions regarding planning, policy, and design to coordinate projects across sectors.
Development of such models poses a number of challenges; (i) scenario generation, (ii)
intelligibility to stakeholders, (iii) validity, (iv) control and feedback, (v) execution time, (vi)
data requirements, (vii) uncertainties and, (viii) flexibility/reusability.
This research has developed a multi-scale flexible framework which disaggregates projected
regional employment to ward-level population, and further to rasterised development. This
comprises; (i) transport network generalised cost, (ii) cost composition, (iii) spatial interaction
incorporating transport accessibility, (iv) development zoning, (v) multi-criteria evaluation of
development suitability, and (vi) cellular development. The framework is generically
implemented, each model being specified in terms of inputs, outputs, and parameters. Modellinkage is via input/output chaining, providing the opportunity to experiment with alternative
solutions. Execution is flexible/configurable to perform multiple model runs whilst varying
parameters and propagating metadata through stages. Python controls execution flow, C++
provides performance, PostgreSQL manages data, and QGIS assists input/output.
The framework is deployed in baseline scenarios for London and Innsbruck, and in more
detailed scenario/uncertainty exploration for London. The framework’s utility is judged by
criteria corresponding to the above challenges and is found to be favourable, with
performance, flexibility and uncertainty support as key attributes. The framework executes
models for London in ~52 seconds on modest hardware (1.6GHz, 8GB). This involves costweighted Dijkstra - 4 transport networks (~42s), cost composition and accessibility
conversion (~4s), spatial interaction - 633 wards (~2s), rasterised 4-hectare development
zones (~1s), 7 criteria development suitability evaluation (~1s), and cellular development -
100m scale (~2s). Combinatorial uncertainties are accommodated by a flexible, modular
structure which promotes reuse, and records run configuration as well as model parameters in
chained metadat
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