5,628 research outputs found
Prediction of heat transfer from laminar boundary layers, with emphasis on large free- stream velocity gradients and highly cooled walls
Prediction of heat transfer and shear stress from laminar boundary laye
Analysis of one dimensional isentropic flow with tables for partially ionized argon
One-dimensional isentropic flow variables of partially ionized argon - tables and data analysi
Semi-classical Laguerre polynomials and a third order discrete integrable equation
A semi-discrete Lax pair formed from the differential system and recurrence
relation for semi-classical orthogonal polynomials, leads to a discrete
integrable equation for a specific semi-classical orthogonal polynomial weight.
The main example we use is a semi-classical Laguerre weight to derive a third
order difference equation with a corresponding Lax pair.Comment: 11 page
On equivariant characteristic ideals of real classes
Let be an odd prime, an abelian totally real number field,
its cyclotomic -extension,
We give an explicit description of the equivariant characteristic ideal of
over for all odd by applying M. Witte's formulation of an equivariant main conjecture (or
"limit theorem") due to Burns and Greither. This could shed some light on
Greenberg's conjecture on the vanishing of the -invariant of
$F_\infty/F.
Observational Diagnoses of Extratropical Ozone STE from 2005-2010
The transport of ozone from the stratosphere to the extratropical troposphere is an important boundary condition to tropospheric chemistry. However, previous direct estimates from models and indirect estimates from observations have poorly constrained the magnitude of ozone stratosphere-troposphere exchange (STE). In this study we provide a direct diagnosis of the extratropical ozone STE using data from the Microwave Limb Sounder on Aura and output of the MERRA reanalysis over the time period from 2005 to the present. We find that the mean annual STE is about 275 Tg yr-1 and 205 Tg yr-1 in the NH and SH, respectively. The interannual variability of the magnitude is about twice as great in the NH than the SH. This variability is dominated by the seasonal variability during the late winter and spring. A comparison of the ozone flux to the mass flux reveals that there is not a simple relationship between the two quantities. This presentation will also examine the magnitude and distribution of ozone in the lower stratosphere relative to the years of maximum and minimum ozone ST
A novel approach to model 4 decades of marine chemical data
The awareness of the negative effects of chemical pollution in the sixties has led to an increased concern on the chemical status of the marine environment in the following decades. International regulation in Europe started with the Oslo and Paris convention in the seventies, later on leading to the OSPAR commission. At national level, extended research on chemical pollutants in marine sediments and marine biota was done within the “Project Mer/Projekt Zee” from 1970 to 1976. Since then, a long series of research and monitoring projects was conducted, reporting on the chemical status of the Belgian Part of the North Sea.
Within the 4demon project, a major work package focused on the collection, quality control and intercalibration of more than 40 years of data on heavy metals and polychlorinated biphenyls. In this presentation, the modelling approach and results on sediment data will be presented.
Within current OSPAR and MSFD monitoring on chemical pollution, variability in location, seasonality, grain size, etc. is reduced thanks to standardized OSPAR guidelines. This facilitates comparability of data within and between regions and assessments based on 5-15 year timetrends are frequently made. Within more than 40 years of pollution data, variability is much larger, and multiple issues should be tackled to intercalibrate the data: changes in sampling locations and analyses methods over time, missing essential metadata, sample analysis on different grain size fractions,… Therefore, existing time trend modelling approaches could not be applied within the 4Demon project. An alternative approach, focused on cluster analysis and different normalisation procedures was proposed. A parametric linear mixed effect model was used to integrate all data into consistent long term time lines which give a view on PCB and heavy metal pollution on a large time frame.
Acknowledgement
We want to thank the Belgian Science Policy Office (BELSPO) for the financial support of the 4Demon project.</p
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