6,767 research outputs found

    On the fine structure of medium energy electron fluxes in the auroral zone and related effects in the ionospheric D-region

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    This study is based on measurements of trapped and precipitated electrons of energy &gt;30 keV and &gt;100 keV observed by polar orbiting environmental satellites during overpasses of the imaging riometer at KilpisjÀrvi, Finland. The satellites are in sun-synchronous orbits of about 850 km altitude, recording the electron fluxes at 2-s time resolution. The riometer measures the radiowave absorption at 38.2 MHz, showing the spatial pattern within a 240 km field of view. <br><br> The analysis has focussed on two areas. Having found a close correlation between the radiowave absorption and the medium-energy electron fluxes during satellite overpasses, empirical relationships are derived, enabling one quantity to be predicted from the other for three sectors of local time. It is shown that small-scale variations observed during a pass are essentially spatial rather than temporal. <br><br> Other properties, such as the spectra and the relation between precipitated and trapped components, are also considered in the light of the theory of pitch angle scattering by VLF waves. It is found that the properties and behaviour depend strongly on the time of day. In the noon sector, the precipitated and trapped fluxes are highly correlated through a square law relationship

    A critical comparison of approaches to resource name management within the IEC common information model

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    Copyright @ 2012 IEEEElectricity network resources are frequently identified within different power systems by inhomogeneous names and identities due to the legacy of their administration by different utility business domains. The IEC 61970 Common Information Model (CIM) enables network modeling to reflect the reality of multiple names for unique network resources. However this issue presents a serious challenge to the integrity of a shared CIM repository that has the task of maintaining a resource manifest, linking network resources to master identities, when unique network resources may have multiple names and identities derived from different power system models and other power system applications. The current approach, using CIM 15, is to manage multiple resource names within a singular CIM namespace utilizing the CIM “IdentifiedObject” and “Name” classes. We compare this approach to one using additional namespaces relating to different power systems, similar to the practice used in CIM extensions, in order to more clearly identify the genealogy of a network resource, provide faster model import times and a simpler means of supporting the relationship between multiple resource names and identities and a master resource identity.This study is supported by the UK National Grid and Brunel University

    Methane cracking over cobalt molybdenum carbides

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    The catalytic behaviour of Co3Mo3C, Co6Mo6C, Co3Mo3N and Co6Mo6N for methane cracking has been studied to determine the relationship between the methane cracking activity and the chemical composition. The characterisation of post-reaction samples showed a complex phase composition with the presence of Co3Mo3C, α-Co and ÎČ-Mo2C as catalytic phases and the deposition of different forms of carbon during reaction

    Revised You’re Welcome Criteria and Future Developments in Adolescent Healthcare

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    In 2011, the Department of Health (England) will publish revised You’re Welcome criteria. This is the first comprehensive attempt to define good quality health services for young people (11-19 years) and provide a self-assessment tool applicable to all adolescent health services. It builds on a growing understanding of the distinctiveness and importance of adolescent health, and the demands placed on adolescent health services. This article reviews changing understandings of the nature of adolescence, including physical, psychological and social transition, evolving patterns of morbidity and mortality, adolescence as part of a life-course approach to health and health behaviours, and the specific needs of young people when using health services. We describe key features of the You're Welcome criteria and discuss the views of young people and professionals involved in revising them, as well as relevant published literature. Lastly, we discuss how the perspective of social paediatrics may be useful in guiding professionals towards a more holistic approach to adolescent care in the future

    Radicals in carbonaceous residue deposited on mordenite from methanol

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    It is shown that control of the degree of coking can lead to the observation of hyperfine structures in the carbonaceous residues deposited from methanol over mordenite (H-MOR) at temperatures relevant to the conversion of methanol to hydrocarbons. EPR measurements of the catalyst samples at various times on stream have been recorded, with a rich hyperfine splitting pattern observed in the early stages of the reaction. Interpretation of the EPR data with the aid of density functional theoretical calculations has afforded the first definitive assignment of the radical cations formed in high temperature coke. The results detail a shortlist of six species: 2,3/2,6/2,7-dimethylnaphthalenium, 2,3,6-trimethylnaphthalenium, 2,3,6,7-tetramethylnaphthalenium, and anthracenium radical cations whose proton hyperfine splitting profiles match the experimental spectra; 2,3,6,7-tetramethylnaphthalenium showed the best agreement. The observation of these particular isomers of polymethylnaphthalene suggest the formation of more highly branched polyaromatic species is less likely within the confines of the H-MOR 12-membered ring channel. These radicals formed when the catalyst is active may constitute key intermediates in the conversion of methanol to light olefins
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