229 research outputs found

    The engineering geology of the Nottingham area, UK

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    Nottingham was built near a crossing point on the River Trent in the East Midlands of England. Initially, the City developed on a low sandstone hill close to the north bank of the river, which provided a secure, well-drained location above the marshes that bordered the river. Geologically, Nottingham stands at the boundary between Palaeozoic rocks to the north and west, and Mesozoic and Cainozoic strata to the south and east. The area is underlain by coal-bearing Carboniferous Coal Measures, Permian dolomitic limestones, Permo-Triassic mudstones and weak sandstones, Jurassic clays and Quaternary glacial and alluvial deposits. Artificial deposits, resulting from the social, industrial and mineral extraction activities of the past cover the natural deposits over much of the area. This geological environment has underpinned the economic development of the area through the mining of coal (now largely ceased), oil extraction that was important during the Second World War, brickmaking from clays, alluvial sand and gravel extraction from the Trent Valley and gypsum extraction from the Permo-Triassic mudstones. The Permo-Triassic sandstone is a nationally important aquifer and has also been exploited at the surface and from shallow mines for sand. However, this history of the use and exploitation of mineral deposits has created a number of environmental problems including rising groundwater levels, abandoned mine shafts and mining subsidence, and, within the City itself, the occasional collapse of artificial cavities in the sandstone and contaminated land left by industrial activities. Natural constraints on development include gypsum dissolution, landslides, rockfalls, swell-shrink problems in Jurassic clays and flooding. Occasional minor earthquakes are attributed to movements due to coal mining or natural, deep geological structures. Thus, Nottingham’s geological context remains an important consideration when planning its future regeneration and development

    A typology of different development and testing options for symbolic regression modelling of measured and calculated datasets

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    AbstractData-driven modelling is used to develop two alternative types of predictive environmental model: a simulator, a model of a real-world process developed from either a conceptual understanding of physical relations and/or using measured records, and an emulator, an imitator of some other model developed on predicted outputs calculated by that source model. A simple four-way typology called Emulation Simulation Typology (EST) is proposed that distinguishes between (i) model type and (ii) different uses of model development period and model test period datasets. To address the question of to what extent simulator and emulator solutions might be considered interchangeable i.e. provide similar levels of output accuracy when tested on data different from that used in their development, a pair of counterpart pan evaporation models was created using symbolic regression. Each model type delivered similar levels of predictive skill to that other of published solutions. Input–output sensitivity analysis of the two different model types likewise confirmed two very similar underlying response functions. This study demonstrates that the type and quality of data on which a model is tested, has a greater influence on model accuracy assessment, than the type and quality of data on which a model is developed, providing that the development record is sufficiently representative of the conceptual underpinnings of the system being examined. Thus, previously reported substantial disparities occurring in goodness-of-fit statistics for pan evaporation models are most likely explained by the use of either measured or calculated data to test particular models, where lower scores do not necessarily represent major deficiencies in the solution itself

    State-of-the-art energetic and morphological modelling of the launching site of the M87 jet

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    M87 has been the target of numerous astronomical observations across the electromagnetic spectrum, and very long baseline interferometry has resolved an edge-brightened jet1,2,3,4. However, the origin and formation of its jets remain unclear. In our current understanding, black holes (BH) are the driving engine of jet formation5, and indeed the recent Event Horizon Telescope observations revealed a ring-like structure in agreement with theoretical models of accretion onto a rotating Kerr BH6. In addition to the spin of the BH being a potential source of energy for the launching mechanism, magnetic fields are believed to play a key role in the formation of relativistic jets7,8. A priori, the spin, a⋆, of the BH in M87⋆ is unknown; however, when accounting for the estimates of the X-ray luminosity and jet power, values of |a_{*}| ≳ 0.5 appear favoured6. Besides the properties of the accretion flow and the BH spin, the radiation microphysics including the particle distribution (thermal6 and non-thermal^{9,10}) as well as the particle acceleration mechanism11 play a crucial role. We show that general relativistic magnetohydrodynamic simulations and general relativistic radiative transfer calculations can reproduce the broadband spectrum from the radio to the near-infrared regime and simultaneously match the observed collimation profile of M87, thus allowing us to set rough constraints on the dimensionless spin of M87* to be 0.5 ≲ a⋆ ≲ 1.0, with higher spins being possibly favoured

    DC Proposal: PRISSMA, Towards Mobile Adaptive Presentation of the Web of Data

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    International audienceThe Mobile Web is evolving fast and mobile access to the Web of Data is gaining momentum. Interlinked RDF resources consumed from portable devices need proper adaptation to the context in which the action is performed. This paper introduces PRISSMA (Presentation of Resources for Interoperable Semantic and Shareable Mobile Adaptability), a domain-independent vocabulary for displaying Web of Data resources in mobile environments. The vocabulary is the first step towards a declarative framework aimed at sharing and re-using presentation information for context-adaptable user interfaces over RDF data

    Resident's preferences for urban brownfield revitalization: Insights from two Czech cities.

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    Residents’ preferences are one of the factors in deciding how brownfields should be revitalized. We compare the views of residents in a city with many brownfields (Karviná) with those in a city with only few brownfields (České Budějovice). We assessed the preferences of residents for four global regeneration alternatives (refurbishment, demolition, open space, (re)development) in three different areas of a city (city centre, inner city, city outskirts). A one percent population sample of two post-socialistic cities in the Czech Republic, was used for the comparison. Positive preferences towards brownfield regeneration were confirmed. We found spatial differences in preferences between refurbishment and demolition of brownfields in each city area: demolition was preferred for inner city brownfields whereas refurbishment was preferred in the city centre and outskirts. Differences were also identified between the two cities: residents of the brownfield rich city preferred demolition, whereas residents of the city with few brownfields preferred refurbishment. Creating new public open space, for residents′ recreation, was given a lower importance within the city centre and a higher significance in outskirts. With the support of a combined ANOVA model, significant differences in residents’ preferences were found for distinct types of regeneration with regards to the cities’ character, the location of brownfields within the city and residents′ proximity
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