293 research outputs found

    Evolution of magnetic fields and energetics of flares in active region 8210

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    To better understand eruptive events in the solar corona, we combine sequences of multi-wavelength observations and modelling of the coronal magnetic field of NOAA AR 8210, a highly flare-productive active region. From the photosphere to the corona, the observations give us information about the motion of magnetic elements (photospheric magnetograms), the location of flares (e.g., Hα\alpha, EUV or soft X-ray brightenings), and the type of events (Hα\alpha blueshift events). Assuming that the evolution of the coronal magnetic field above an active region can be described by successive equilibria, we follow in time the magnetic changes of the 3D nonlinear force-free (nlff) fields reconstructed from a time series of photospheric vector magnetograms. We apply this method to AR 8210 observed on May 1, 1998 between 17:00 UT and 21:40 UT. We identify two types of horizontal photospheric motions that can drive an eruption: a clockwise rotation of the sunspot, and a fast motion of an emerging polarity. The reconstructed nlff coronal fields give us a scenario of the confined flares observed in AR 8210: the slow sunspot rotation enables the occurence of flare by a reconnection process close to a separatrix surface whereas the fast motion is associated with small-scale reconnections but no detectable flaring activity. We also study the injection rates of magnetic energy, Poynting flux and relative magnetic helicity through the photosphere and into the corona. The injection of magnetic energy by transverse photospheric motions is found to be correlated with the storage of energy in the corona and then the release by flaring activity. The magnetic helicity derived from the magnetic field and the vector potential of the nlff configuration is computed in the coronal volume. The magnetic helicity evolution shows that AR 8210 is dominated by the mutual helicity between the closed and potential fields and not by the self helicity of the closed field which characterizes the twist of confined flux bundles. We conclude that for AR 8210 the complex topology is a more important factor than the twist in the eruption process

    What memory binding functions is the hippocampus responsible for?

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    The role of the hippocampus in binding information in working memory (WM) is little understood. When complex experiences comprise associations between different pieces of information such as objects and locations (relational binding), the function of the hippocampus is required to hold them in WM (Mitchell et al., 2000; 2006; Piekema, 2006). However, recent evidence suggests that if the to-be-associated information leads to the formation of integrated objects such as coloured shapes (conjunctive binding), the hippocampus is less involved in holding temporary representations of these complex events in WM (Baddeley et al., 2010; Piekema, 2006). We investigated the relational and conjunctive binding hypotheses of the hippocampal functions in a patient with right hippocampal damage. The patient and controls were asked to study visual arrays of stimuli which consisted of shape-colour relations (shape-colour pairs) or shape-colour conjunctions (coloured shapes). After the study array, they were presented with a new screen consisting of one set of shapes (line drawings) and one set of colours. They were asked to reconstruct the bindings by selecting the shapes and their corresponding colours. As compared to healthy controls, the patient was impaired in holding relations of shapes and colours in WM whereas he could retain the conjunctions similarly to controls. These results lend support to the role of the hippocampus in supporting memory for inter-item associations but not memory for conjunctions of features which define objects' identity

    A Study of Risk Management Practice of Highway Projects in Nigeria

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    Construction Risk Management must be given adequate attention in order to ensure a successful project that meets the expectation of project goals and objectives thus risk management practice in Nigeria with respect to highway projects is explored in this study. Questionnaire survey was adopted for a population of 82 professionals (highway engineers, quantity surveyors and land surveyors) in clients, consultants and contracting organisations, using stratified random sampling techniques. The data collected were analysed by determination of the mean of the responses from the respondents and one way Analysis of Variance (ANOVA). Result of the analysis showed that; lack of accepted industry model for analysis of risk is rated as the most influencing factor in the implementation of risk management practice in Nigeria, followed by human/ organizational resistance. There is no significant difference at 5% level of significance between the responses of the clients, consultants and contractors on risk identification tools usage and risks response tools usage, risks analysis techniques usage of all the respondents except algorithms and Monte Carlo simulation. The result further showed that risk management practice is low in Nigeria, as all the respondents agreed that the use of rule of thumbs in managing construction risks associated with highways is prevalent as against modern techniques that are widely in use in developed countries. The study recommended adequate training for all stakeholders in highway construction sector to improve management of risks thus meeting project goals of time, approved budgets, and quality, imbibing the health and safety culture,  and in an environmentally acceptable manner. Keywords: Development, Highways, Risk management

    Application of users’ light-switch stochastic models to dynamic energy simulation

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    The design of an innovative building should include building overall energy flows estimation. They are principally related to main six influencing factors (IEA-ECB Annex 53): climate, building envelope and equipment, operation and maintenance, occupant behaviour and indoor environment conditions. Consequently, energy-related occupant behaviour should be taken into account by energy simulation software. Previous researches (Bourgeois et al. 2006, Buso 2012, Fabi 2012) already revealed the differences in terms of energy loads between considering occupants' behaviour as stochastic processes rather than deterministic inputs, due to the uncertain nature of human behaviour. In this paper, new stochastic models of users’ interaction with artificial lighting systems are developed and implemented in the energy simulation software IDA ICE. They were developed from field measurements in an office building in Prague. The aim is to evaluate the impact of a user's switching action over whole building energy consumption. Indeed, it is interesting not only to see the variance related to electric energy consumption, but the overall effect on a building's energy load

    Application of users’ light-switch stochastic models to dynamic energy simulation

    Get PDF
    The design of an innovative building should include building overall energy flows estimation. They are principally related to main six influencing factors (IEA-ECB Annex 53): climate, building envelope and equipment, operation and maintenance, occupant behaviour and indoor environment conditions. Consequently, energy-related occupant behaviour should be taken into account by energy simulation software. Previous researches (Bourgeois et al. 2006, Buso 2012, Fabi 2012) already revealed the differences in terms of energy loads between considering occupants' behaviour as stochastic processes rather than deterministic inputs, due to the uncertain nature of human behaviour. In this paper, new stochastic models of users’ interaction with artificial lighting systems are developed and implemented in the energy simulation software IDA ICE. They were developed from field measurements in an office building in Prague. The aim is to evaluate the impact of a user's switching action over whole building energy consumption. Indeed, it is interesting not only to see the variance related to electric energy consumption, but the overall effect on a building's energy load

    The BlueBio project’s database: web-mapping cooperation to create value for the Blue Bioeconomy

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    Funding innovation requires knowledge on previous/on-going research and identification of gaps and synergies among actors, networks and projects, but targeted databases remain scattered, incomplete and scarcely searchable. Here we present the BlueBio database: a first comprehensive and robust compilation of internationally and nationally funded research projects active in the years 2003–2019 in Fisheries, Aquaculture, Seafood Processing and Marine Biotechnology. Based on the previous research projects’ database realized in the framework of the COFASP ERA-NET, it was implemented within the ERA-NET Cofund BlueBio project through a 4-years data collection including 4 surveys and a wide data retrieval. After being integrated, data were harmonised, shared as open and disseminated through a WebGIS that was key for data entry, update and validation. The database consists of 3,254 “georeferenced” projects, described by 22 parameters that are clustered into textual and spatial, some directly collected while others deduced. The database is a living archive to inform actors of the Blue Bioeconomy sector in a period of rapid transformations and research needs and is freely available at: https://doi.org/10.6084/m9.figshare.21507837.v3

    Impact of occupant behaviour on the energy-saving potential of retrofit measures for a public building in the UK

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    This is an Accepted Manuscript of an article published by Taylor & Francis in Intelligent Buildings International on 06 Feb 2016, available online: http://dx.doi.org/10.1080/17508975.2016.1139538© 2016 Taylor & Francis In building refurbishment projects, dynamic building simulation is popularly used to predict the energy-saving potential of various refurbishment scenarios. However, in this process, it is not clear whether occupant behaviour should be carefully modelled due to the lack of evidence about its impact on the prediction results. To answer this question, this study selected a UK public building and used dynamic building simulation to predict the energy-saving potential of common refurbishment measures, under various occupant behavioural conditions. The results revealed that for the case study building occupants’ heating behaviour has a significant impact on the predicted energy-saving potential of all evaluated refurbishment measures: when changing from passive heating users to active heating users, the energy-saving potential was nearly doubled. Although occupants’ window opening behaviour was not shown to be as important as heating behaviour for the refurbishment of the case study building, it has a specific influence on the refurbishment measure of increasing window layers: when windows are opened longer, the effectiveness of increasing window layers on promoting the building energy efficiency is decreased. According to the findings from this study, occupant behaviour should be considered as an important aspect in building refurbishment projects
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