33,093 research outputs found

    The Surface Energy Balance System (SEBS) for estimation of turbulent heat fluxes

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    A Surface Energy Balance System (SEBS) is proposed for the estimation of atmospheric turbulent fluxes and evaporative fraction using satellite earth observation data, in combination with meteorological information at proper scales. SEBS consists of: a set of tools for the determination of the land surface physical parameters, such as albedo, emissivity, temperature, vegetation coverage etc., from spectral reflectance and radiance measurements; a model for the determination of the roughness length for heat transfer; and a new formulation for the determination of the evaporative fraction on the basis of energy balance at limiting cases. Four experimental data sets are used to assess the reliabilities of SEBS. Based on these case studies, SEBS has proven to be capable to estimate turbulent heat fluxes and evaporative fraction at various scales with acceptable accuracy. The uncertainties in the estimated heat fluxes are comparable to in-situ measurement uncertainties.</p> <p style='line-height: 20px;'><b>Keywords:</b> Surface energy balance, turbulent heat flux, evaporation, remote sensin

    The definition of "Insider" in section 3 of the securities markets Act 1988: A review and comparison with other jurisdictions

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    Statutory definitions of what constitutes an “insider” for the purposes of insider trading laws may be based on either a “person connection” approach or an “information connection” approach. The “person connection” approach defines “insider” by reference to the relationship of the person to the public issuer of securities, while the “information connection” approach considers anyone who has material price-sensitive information about the issuer to be an insider, regardless of his or her relationship to the issuer. In common with Japan, Hong Kong and China, New Zealand’s insider trading law — the Securities Markets Act 1988 — uses a person connection approach in its definition of “insider”. Other jurisdictions, however, including both the United Kingdom and Australia, have, to varying degrees, recently amended their definitions to reflect the information connection approach. The United States, although the first country to address the issue of insider trading, lacks a statutory definition of “insider” and instead relies on generally applicable laws against securities fraud. It has developed a definition with elements of both approaches. This paper reviews the definitions in use in the United States and in other countries (including New Zealand) which have been influenced by the American experience. It concludes that the narrow, relationship-based approach does not capture some conduct that may be damaging to the integrity of the securities market. A definition based on the information connection approach (perhaps combined with elements of the person connection approach) may therefore be preferable to New Zealand’s current definition

    EAGLE 2006 – Multi-purpose, multi-angle and multi-sensor in-situ and airborne campaigns over grassland and forest

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    EAGLE2006 - an intensive field campaign - was carried out in the Netherlands from the 8th until the 18th of June 2006. Several airborne sensors - an optical imaging sensor, an imaging microwave radiometer, and a flux airplane – were used and extensive ground measurements were conducted over one grassland (Cabauw) site and two forest sites (Loobos & Speulderbos) in the central part of the Netherlands, in addition to the acquisition of multi-angle and multi-sensor satellite data. The data set is both unique and urgently needed for the development and validation of models and inversion algorithms for quantitative surface parameter estimation and process studies. EAGLE2006 was led by the Department of Water Resources of the International Institute for Geo-Information Science and Earth Observation and originated from the combination of a number of initiatives coming under different funding. The objectives of the EAGLE2006 campaign were closely related to the objectives of other ESA Campaigns (SPARC2004, Sen2Flex2005 and especially AGRISAR2006). However, one important objective of the campaign is to build up a data base for the investigation and validation of the retrieval of bio-geophysical parameters, obtained at different radar frequencies (X-, C- and L-Band) and at hyperspectral optical and thermal bands acquired over vegetated fields (forest and grassland). As such, all activities were related to algorithm development for future satellite missions such as Sentinels and for satellite validations for MERIS, MODIS as well as AATSR and ASTER thermal data validation, with activities also related to the ASAR sensor on board ESA’s Envisat platform and those on EPS/MetOp and SMOS. Most of the activities in the campaign are highly relevant for the EU GEMS EAGLE project, but also issues related to retrieval of biophysical parameters from MERIS and MODIS as well as AATSR and ASTER data were of particular relevance to the NWO-SRON EcoRTM project, while scaling issues and complementary between these (covering only local sites) and global sensors such as MERIS/SEVIRI, EPS/MetOP and SMOS were also key elements for the SMOS cal/val project and the ESA-MOST DRAGON programme. This contribution describes the mission objectives and provides an overview of the airborne and field campaigns

    Hydrostatic pressure effects on the static magnetism in Eu(Fe0.925_{0.925}Co0.075_{0.075})2_{2}As2_{2}

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    The effects of hydrostatic pressure on the static magnetism in Eu(Fe0.925_{0.925}Co0.075_{0.075})2_{2}As2_{2} are investigated by complementary electrical resistivity, ac magnetic susceptibility and single-crystal neutron diffraction measurements. A specific pressure-temperature phase diagram of Eu(Fe0.925_{0.925}Co0.075_{0.075})2_{2}As2_{2} is established. The structural phase transition, as well as the spin-density-wave order of Fe sublattice, is suppressed gradually with increasing pressure and disappears completely above 2.0 GPa. In contrast, the magnetic order of Eu sublattice persists over the whole investigated pressure range up to 14 GPa, yet displaying a non-monotonic variation with pressure. With the increase of the hydrostatic pressure, the magnetic state of Eu evolves from the canted antiferromagnetic structure in the ground state, via a pure ferromagnetic structure under the intermediate pressure, finally to a possible "novel" antiferromagnetic structure under the high pressure. The strong ferromagnetism of Eu coexists with the pressure-induced superconductivity around 2 GPa. The change of the magnetic state of Eu in Eu(Fe0.925_{0.925}Co0.075_{0.075})2_{2}As2_{2} upon the application of hydrostatic pressure probably arises from the modification of the indirect Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between the Eu2+^{2+} moments tuned by external pressure.Comment: 9 pages, 6 figure
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