12,657 research outputs found
Re-use of an ontology for modelling urban energy systems
The use of ontologies for the interoperability of software models is widespread, with many applications also in the energy domain. By formulating a shared data structure and a definition of concepts and their properties, a language is created that can be used between modellers and - formalised in an ontology - between model components. When modelling energy systems, connections between different infrastructures are critical, e.g. the interaction between the gas and electricity markets or the need for various infrastructures including power, heat, water and transport in cities. While a commonly shared ontology of energy systems would be highly desirable, the fact is that different existing models or applications already use dedicated ontologies, and have been demonstrated to work well using them. To benefit from linking data sources and connecting models developed with different ontologies, a translation between concepts can be made. In this paper a model of an urban energy system built upon one ontology is initialised using energy transformation technologies defined in another ontology, thus illustrating how this common perspective might benefit researchers in the energy domain. ©2010 IEEE
Improving water productivity in agriculture in developing economies: in search of new avenues
Water ProductivityCrop productionWheatCottonEvapotranspirationEcnomic aspects
A correction procedure for the errors in single-crystal intensities due to the inhomogeneity of the primary X-ray beam
Graphite monochromators are known to give rise to non-homogeneous primary X-ray beams. When intensities of single crystals are measured the effective cross section of a non-spherical crystal in the X-ray beam depends on its orientation in the beam. Therefore, systematic errors in the measured integrated intensities are introduced by the inhomogeneity of the incoming beam. A correction for these errors can be made, knowing the intensity profile of the primary beam and the dimensions and orientation of the crystal in the beam. The correction can conveniently be applied with the absorption correction. Examples of the corrections are given for crystals with rational boundary planes. It is shown that the intensity of an X-ray reflection as a function of the rotation about the scattering vector ( rotation) can be calculated with fair accuracy. In some cases (large elongated crystals in an inhomogeneous beam) correction for absorption only may give results which are worse than those with no correction at all
Neutrix Calculus and Finite Quantum Field Theory
In general, quantum field theories (QFT) require regularizations and infinite
renormalizations due to ultraviolet divergences in their loop calculations.
Furthermore, perturbation series in theories like QED are not convergent
series, but are asymptotic series. We apply neutrix calculus, developed in
connection with asymptotic series and divergent integrals, to QFT,obtaining
finite renormalizations. While none of the physically measurable results in
renormalizable QFT is changed, quantum gravity is rendered more manageable in
the neutrix framework.Comment: 10 pages; LaTeX; version to appear in J. Phys. A: Math. Gen. as a
Letter to the Edito
Spacetime Foam, Holographic Principle, and Black Hole Quantum Computers
Spacetime foam, also known as quantum foam, has its origin in quantum
fluctuations of spacetime. Arguably it is the source of the holographic
principle, which severely limits how densely information can be packed in
space. Its physics is also intimately linked to that of black holes and
computation. In particular, the same underlying physics is shown to govern the
computational power of black hole quantum computers.Comment: 8 pages, LaTeX; Talk given by Jack Ng, in celebration of Paul
Frampton's 60th birthday, at the Coral Gables Conference (in Fort Lauderdale,
Florida on December 17, 2003). To appear in the Proceedings of the 2003 Coral
Gables Conferenc
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