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See detailComparisons between ground-based FTIR and MIPAS N2O and HNO3 profiles before and after assimilation in BASCOE
Vigouroux, Corinne; De Mazière, Martine; Errera, Quentin et al

in Atmospheric Chemistry and Physics (2007), 7

Within the framework of the Network for Detection of Atmospheric Composition Change (NDACC), regular ground-based Fourier transform infrared ( FTIR) measurements of many species are performed at several ... [more ▼]

Within the framework of the Network for Detection of Atmospheric Composition Change (NDACC), regular ground-based Fourier transform infrared ( FTIR) measurements of many species are performed at several locations. Inversion schemes provide vertical profile information and characterization of the retrieved products which are therefore relevant for contributing to the validation of MIPAS profiles in the stratosphere and upper troposphere. We have focused on the species HNO3 and N2O at 5 NDACC-sites distributed in both hemispheres, i.e., Jungfraujoch (46.5 degrees N) and Kiruna (68 degrees N) for the northern hemisphere, and Wollongong (34 degrees S), Lauder (45 degrees S) and Arrival Heights (78 degrees S) for the southern hemisphere. These ground-based data have been compared with MIPAS offline profiles (v4.61) for the year 2003, collocated within 1000 km around the stations, in the lower to middle stratosphere. To get around the spatial collocation problem, comparisons have also been made between the same ground-based FTIR data and the corresponding profiles resulting from the stratospheric 4D-VAR data assimilation system BASCOE constrained by MIPAS data. This paper discusses the results of the comparisons and the usefullness of using BASCOE profiles as proxies for MIPAS data. It shows good agreement between MIPAS and FTIR N2O partial columns: the biases are below 5% for all the stations and the standard deviations are below 7% for the three mid-latitude stations, and below 10% for the high latitude ones. The comparisons with BASCOE partial columns give standard deviations below 4% for the mid-latitude stations to less than 8% for the high latitude ones. After making some corrections to take into account the known bias due to the use of different spectroscopic parameters, the comparisons of HNO3 partial columns show biases below 3% and standard deviations below 15% for all the stations except Arrival Heights ( bias of 5%, standard deviation of 21%). The results for this species, which has a larger spatial variability, highlight the necessity of defining appropriate collocation criteria and of accounting for the spread of the observed air-masses. BASCOE appears to have more deficiencies in producing proxies of MIPAS HNO3 profiles compared to N2O, but the obtained standard deviation of less than 10% between BASCOE and FTIR is reasonable. Similar results on profiles comparisons are also shown in the paper, in addition to partial column ones. [less ▲]

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See detailComparisons between SCIAMACHY and ground-based FTIR data for total columns of CO, CH4, CO2 and N2O
Dils, Bart; De Mazière, Martine; Muller, Jean-François et al

in Atmospheric Chemistry and Physics (2006), 6

Total column amounts of CO, CH4, CO2 and N2O retrieved from SCIAMACHY nadir observations in its near-infrared channels have been compared to data from a ground-based quasi-global network of Fourier ... [more ▼]

Total column amounts of CO, CH4, CO2 and N2O retrieved from SCIAMACHY nadir observations in its near-infrared channels have been compared to data from a ground-based quasi-global network of Fourier-transform infrared ( FTIR) spectrometers. The SCIAMACHY data considered here have been produced by three different retrieval algorithms, WFM-DOAS (version 0.5 for CO and CH4 and version 0.4 for CO2 and N2O), IMAP- DOAS ( version 1.1 and 0.9 (for CO)) and IMLM (version 6.3) and cover the January to December 2003 time period. Comparisons have been made for individual data, as well as for monthly averages. To maximize the number of reliable coincidences that satisfy the temporal and spatial collocation criteria, the SCIAMACHY data have been compared with a temporal 3rd order polynomial interpolation of the ground-based data. Particular attention has been given to the question whether SCIAMACHY observes correctly the seasonal and latitudinal variability of the target species. The present results indicate that the individual SCIAMACHY data obtained with the actual versions of the algorithms have been significantly improved, but that the quality requirements, for estimating emissions on regional scales, are not yet met. Nevertheless, possible directions for further algorithm upgrades have been identified which should result in more reliable data products in a near future. [less ▲]

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See detailComparisons between SCIAMACHY Scientific Products and Ground-Based FTIR Data for Total Columns of CO, CH4 and N2O
De Mazière, M.; Barret, B.; Blumenstock, T. et al

Scientific conference (2004, May)

Total column amounts of CO, CH4 and N2O retrieved from SCIAMACHY nadir observations in its near-infrared channels have been compared to data from a ground-based network of Fourier-transform infrared (FTIR ... [more ▼]

Total column amounts of CO, CH4 and N2O retrieved from SCIAMACHY nadir observations in its near-infrared channels have been compared to data from a ground-based network of Fourier-transform infrared (FTIR) spectrometers as well as to data obtained with an FTIR instrument during a ship cruise in January-February 2003, along the African West Coast. The SCIAMACHY data considered here have been produced by two different scientific retrieval algorithms, wfm-doas (version 4.0) and IMLM (version 5.1), and cover different time periods, making the number of reliable coincidences that satisfy the temporal and spatial collocation criteria rather limited and different for both. Also the quality of the SCIAMACHY Level 1 data, and thus of the Level 2 data for the different time periods is very different. Still the comparisons demonstrate the capability of SCIAMACHY, using one of both algorithms, to deliver geophysically valuable products for the target species under consideration, on a global scale. [less ▲]

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See detailComparisons between stellar models and reliability of the theoretical models
Lebreton, Yveline; Montalban Iglesias, Josefa ULg

in Astrophysics & Space Science (2010), 328

The high quality of the asteroseismic data provided by space missions such as CoRoT (Michel et al. in The CoRoT Mission, ESA Spec. Publ. vol. 1306, p. 39, 2006) or expected from new operating missions ... [more ▼]

The high quality of the asteroseismic data provided by space missions such as CoRoT (Michel et al. in The CoRoT Mission, ESA Spec. Publ. vol. 1306, p. 39, 2006) or expected from new operating missions such as Kepler (Christensen-Dalsgaard et al. in Commun. Asteroseismol. 150:350, 2007) requires the capacity of stellar evolution codes to provide accurate models whose numerical precision is better than the expected observational errors (i.e. below 0.1 μHz on the frequencies in the case of CoRoT). We present a review of some thorough comparisons of stellar models produced by different evolution codes, involved in the CoRoT/ESTA activities (Monteiro in Evolution and Seismic Tools for Stellar Astrophysics, 2009). We examine the numerical aspects of the computations as well as the effects of different implementations of the same physics on the global quantities, physical structure and oscillations properties of the stellar models. We also discuss a few aspects of the input physics. [less ▲]

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See detailComparisons in Migration Studies
Martiniello, Marco ULg

in Journal of Comparative Migration Studies (2013), 1(1), 7-22

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See detailComparisons of anisotropic elastoplastic laws applied to steel sheet
Habraken, Anne ULg; Radu, Jean-Pol ULg; Duchene, Laurent ULg et al

in International Conference NUMIFORM 1998 (1998, June)

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See detailComparisons of FEM approaches modelling the metal plastic behaviour
Habraken, Anne ULg; Gerday, Anne-Françoise ULg; Diouf, B. et al

in Cueto, Elías; Chinesta, Francisco (Eds.) Proceedings of the 10th ESAFORM Conference on Material Forming (2007)

Simple phenomenological laws (e.g. classical Hill 1948 quadratic law) are compared to more complex laws based on crystal plasticity through various numerical simulations: mechanical tests of ECAE ... [more ▼]

Simple phenomenological laws (e.g. classical Hill 1948 quadratic law) are compared to more complex laws based on crystal plasticity through various numerical simulations: mechanical tests of ECAE materials, nanoindentation of titanium alloys and copper, and large strain torsion of copper bars. Taking into consideration the complexity of the investigated processes, the numerical results present rather good agreements with experimental observations. [less ▲]

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See detailComparisons of finite element and Rayleigh methods for the study of conical Bloch waves in arrays of metallic cylinders
Guenneau, S.; Nicolet, A.; Geuzaine, Christophe ULg et al

in COMPEL (2004), 23(4), 932--949

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See detailComparisons of long-term stratospheric nitric acid and hydrogen fluoride variations using satellite and ground-based measurements
Froidevaux, L.; Anderson, J.; Hannigan, J. et al

Conference (2011, November 09)

We investigate the long-term variations of stratospheric nitric acid (HNO3) and hydrogen fluoride (HF), based on several satellite and ground-based measurement records. We use results from the Upper ... [more ▼]

We investigate the long-term variations of stratospheric nitric acid (HNO3) and hydrogen fluoride (HF), based on several satellite and ground-based measurement records. We use results from the Upper Atmosphere Research Satellite (launched in late 1991 and decommissioned in late 2005), the Aura satellite (launched in summer 1991, with on-going measurements), and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) (from 2004 to present), in conjunction with several long-term ground-based datasets from the Network for the Detection of Atmosphere Composition Change (NDACC). In particular, we investigate the time series of HNO3 and HF, using NDACC column data for validation. We focus here on a few NDACC sites with long-term and frequent measurements, namely the Jungfraujoch (45N, 8E), Lauder (45S, 170E), and Mauna Loa (20N, 204E) sites, where ground-based Fourier Transform Infrared (FTIR) measurements have covered both the UARS and Aura time periods (1991 to present). For HNO3, we investigate whether there are indications of a systematic offset between the measurements by the Microwave Limb Sounder (MLS) instruments aboard both UARS and Aura. For hydrogen fluoride, the HALogen Occultation Experiment's HF time series are connected to the ACE-FTS dataset, and we analyze the correlation of this time series with the ground-based datasets. In addition, model runs from the Whole Atmosphere Community Climate Model (WACCM) and the TOMCAT/SLIMCAT model are used as part of the long-term time series intercomparisons. We note that there is a significant time gap in the HNO3 time series from the satellite measurements used here. The long-term satellite datasets studied here include zonal average Earth Science Data Records (ESDRs) being produced under the Global Ozone Chemistry And Related trace gas Data records for the Stratosphere (GOZCARDS) project, part of the NASA Making Earth Science data records for Use in Research Environments (MEaSUREs) program. We also analyze coincident-type measurements, for the comparisons between satellite and ground-based observations. [less ▲]

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See detailComparisons of Saturn Kilometric Radiation and Saturn's UV Aurora
Kurth, William; Gurnett, D. A.; Clarke, J. T. et al

Conference (2004, May 17)

During the period 8 to 30 January 2004, a campaign to study the correlation between the solar wind and the response of Saturn's aurora was carried out using Cassini and the Hubble Space Telescope. In ... [more ▼]

During the period 8 to 30 January 2004, a campaign to study the correlation between the solar wind and the response of Saturn's aurora was carried out using Cassini and the Hubble Space Telescope. In particular, fields and particles instruments on Cassini were used to monitor the solar wind near Saturn and Saturn kilometric radio emissions nearly continuously. STIS images from Hubble were obtained approximately every other day to record Saturn's UV auroral morphology and intensity. In this paper we focus particularly on the relationship between the Saturn kilometric emissions and the auroral brightness and morphology. The radio emissions are generally believed to be generated by the cyclotron maser instability on auroral field lines similar to the situation for auroral kilometric radiation at Earth. A number of studies have shown a direct relationship between the radio emissions and discrete auroral arcs at Earth. Hence, one expects a relationship between the radio emissions and the aurora at Saturn. During the campaign, two corotating interaction regions (CIRs) swept past Cassini and Saturn (which were of order 0.5 AU apart at the time). Accompanying the CIRs were high solar wind densities. As expected from Voyager studies, the higher solar wind density resulted in generally more intense radio emissions. The UV images show that Saturn's UV aurora brighten considerably in response to the CIRs, as well. Furthermore, the brightest aurora usually appear in the local morning, consistent with the Voyager-determined SKR source region on field lines connecting to the magnetopause and the Kelvin-Helmholtz hypothesis for the origin of accelerated electrons. A more detailed examination of the auroral phenomena show much more complex variations, however. The radio emission frequency extent and peak frequency vary remarkably from one Saturn rotation to the next. Similarly, the auroral morphology changes dramatically. For example, it appears the evolution of the auroral oval to higher latitudes (higher L-shells) is correlated with a shift in the frequency of peak radio emissions to lower frequencies. This can be explained through an analysis of the cyclotron maser beaming geometry. We examine this and other aspects of the correlations between the radio emissions and the aurora. [less ▲]

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See detailA compartimentalized model for trickle flow through packed beds based on x-ray tomograms
Toye, Dominique ULg; Marchot, Pierre ULg; Crine, Michel ULg et al

in Flamand, G. (Ed.) Récents Progrès en Génie des procédés - N°69 - Tools fro process understanding and control - Proceedings of the 2nd European Congress on Chemical Engineering – ECCE2, 05 – 07 octobre 1999, Montpellier, France (1999)

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See detailThe Compartmentation of Phosphorylated Thiamine Derivatives in Cultured Neuroblastoma Cells
Bettendorff, Lucien ULg

in Biochimica et Biophysica Acta (1994), 1222(1), 7-14

Thiamine transport in cultured neuroblastoma cells is mediated by a high-affinity carrier (KM = 40 nM). In contrast, the uptake of the more hydrophobic sulbutiamine (isobutyrylthiamine disulfide) is ... [more ▼]

Thiamine transport in cultured neuroblastoma cells is mediated by a high-affinity carrier (KM = 40 nM). In contrast, the uptake of the more hydrophobic sulbutiamine (isobutyrylthiamine disulfide) is unsaturable and its initial transport rate is 20-times faster than for thiamine. In the cytoplasm, sulbutiamine is rapidly hydrolyzed and reduced to free thiamine, the overall process resulting in a rapid and concentrative thiamine accumulation. Incorporation of radioactivity from [14C]thiamine or [14C]sulbutiamine into intracellular thiamine diphosphate is slow in both cases. Despite the fact that the diphosphate is probably the direct precursor for both thiamine monophosphate and triphosphate, the specific radioactivity increased much faster for the latter two compounds than for thiamine diphosphate. This suggests the existence of two pools of thiamine diphosphate, the larger one having a very slow turnover (about 17 h); a much smaller, rapidly turning over pool would be the precursor of thiamine mono- and triphosphate. The turnover time for thiamine triphosphate could be estimated to be 1-2 h. When preloading the cells with [14C]sulbutiamine was followed by a chase with the same concentration of the unlabeled compound, the specific radioactivities of thiamine and thiamine monophosphate decreased exponentially as expected, but labeling of the diphosphate continued to increase slowly. Specific radioactivity of thiamine triphosphate increased first, but after 30 min it began to slowly decrease. These results show for the first time the existence of distinct thiamine diphosphate pools in the same homogeneous cell population. They also suggest a complex compartmentation of thiamine metabolism. [less ▲]

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See detailLa compatibilité de l’article 80 de la loi sur les pratiques de commerce avec l’article 29 du Traité CE
Defossez, Alexandre ULg

in Revue de Droit Commercial Belge = Tijdschrift voor Belgisch Handelsrecht (2009)

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See detailLa compatibilité du métier de secrétaire communal avec d’autres fonctions : aperçu de lege lata, de lege peractura et de lege ferenda
Donnay, Luc ULg

in L'indépendance du secrétaire communal : utopie ou réalité? (2012)

Il s'agit d'un examen de la compatibilité du métier de secrétaire communal avec d'autres fonctions au regard de la situation législative actuelle et des projets de réformes en cours.

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See detailCompatibility between fibers and modified bitumen
Courard, Luc ULg; Rigo, Jean-Marie ULg; Degeimbre, Robert ULg et al

in Rigo, Jean-Marie; Degeimbre, Robert (Eds.) Reflective cracking in pavements - Assessment and control (1989)

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See detailCompatibility of using TiO2 and the faecal near-infrared reflectance spectrometry for estimation of cattle intake
Vandermeulen, Sophie ULg; Decruyenaere, Virginie; Ramirez-Restrepo, Carlos Alberto et al

in EGF at 50: the future of European Grasslands. Proceedings of the 25th General Meeting of the European Grassland Federation, Aberystwyth, Wales, U.K., 7 - 11th September 2014 (in press)

Combining titanium dioxide (TiO2) as indigestible marker to faecal near-infrared reflectance spectrometry (F-NIRS) can be used to determine cattle feed intake and quality of ingested forage if F-NIRS ... [more ▼]

Combining titanium dioxide (TiO2) as indigestible marker to faecal near-infrared reflectance spectrometry (F-NIRS) can be used to determine cattle feed intake and quality of ingested forage if F-NIRS spectra are not modified by the marker. This study aimed at determining the compatibility of TiO2 with F-NIRS. Three dry cows were fed a standard hay-based diet for three weeks supplemented with a daily dose of 0.1 % (10g) TiO2 during the last two weeks of the experiment. Faeces samples were collected every day and analysed for TiO2 and F-NIRS. Results suggest that TiO2 did not interfere with F-NIRS analyses. The calculations of crude protein, NDF, ADL contents, as well as dry matter intake did not change over time with increasing TiO2 in the faeces (P > 0.05). Slight differences observed for other predicted parameters seemed to be independent from TiO2. The higher Mahalanobis distance (H) for chemical composition (H = 7.2) independent from TiO2 inclusion could indicate that faecal spectra did not correspond exactly to the prediction database. Although 0.1% incorporation of TiO2 seem not to interfere with F-NIRS measurements, caution must be taken with higher levels of TiO2 as nothing indicates that interference could not appear. [less ▲]

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See detailCompatibility performance as a fundamental requirement for the repair of concrete structures with Self-Compacting Repair Mortars
Courard, Luc ULg; Bissonnette, Benoît

in De Schutter, Geert; Boel, V. (Eds.) Self Compacting Concrete SCC2007 (2007, September)

Durable adhesion of repair material on concrete substrate requires compatibility between the materials to be bonded. There are four main compatibility components to be addressed in any concrete repair ... [more ▼]

Durable adhesion of repair material on concrete substrate requires compatibility between the materials to be bonded. There are four main compatibility components to be addressed in any concrete repair scenario: dimensional, permeability, chemical and electrochemical compatibility. Among those, dimensional compatibility is often prevalent: while a cement-base repair material inevitably undergoes shrinkage, the substrate opposes to its free movement, a situation that can lead to cracking and, subsequently, promote debonding. Besides, an essential requirement for bond development is the creation of the interface itself: the intimate contact between the repair system and concrete substrate is required in order to maximize adhesion. Adequate compaction of the new layer is consequently one of the main parameters that will govern the quality of the bond: sufficient vibration or specific rheological properties for the repair material are needed. Self-Compacting Repair Mortar (SCRM) can be advantageously used in many repair situations. Limestone fillers seem to offer interesting advantages as addition to these repair materials as they increase the workability of the final product. Several materials have been tested and characterised by means of a physical, chemical and mechanical characterization test program: specific attention has been given to water demand and superplasticizer efficiency. [less ▲]

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See detailCompatibilization of immiscible polymer blends (PV/PVDF) by the addition of a third polymer (PMMA): analysis of phase morphology and mechanical properties
Moussaif, Noureddin; Jérôme, Robert ULg

in Polymer (1999), 40(14), 3919-3932

Compatibilization of the immiscible polycarbonate (PC)/polyvinylidenefluoride (PVDF) pair by a third homopolymer, i.e. polymethylmethacrylate (PMMA), was studied in relation to phase morphology and ... [more ▼]

Compatibilization of the immiscible polycarbonate (PC)/polyvinylidenefluoride (PVDF) pair by a third homopolymer, i.e. polymethylmethacrylate (PMMA), was studied in relation to phase morphology and mechanical properties of the polyblends. Scanning electron microscopy showed a more regular and finer phase dispersion when the original PMMA content in PVDF exceeded 20 wt.%. The premixing of PVDF with ca. 40 wt.% PMMA also had a beneficial effect on mechanical properties, such as ultimate tensile strength, elongation at break, and notched impact strength. All these experimental results are consistent with the interfacial activity of PMMA in the PC/PVDF blends. [less ▲]

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