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See detailOn the spectral bands measurements for combustion monitoring
Arias, Luis; Torres, S; Sbarbaro, D et al

in Combustion and Flame (2011), 158

In this work, spatial–spectral experimental issues affecting the detection of radical emissions in a natural gas flame are discussed and studied by a radiometric analysis of the flame spectral emission ... [more ▼]

In this work, spatial–spectral experimental issues affecting the detection of radical emissions in a natural gas flame are discussed and studied by a radiometric analysis of the flame spectral emission. As results of this analysis, Local and Global Spectral Radiation Measurements (LSRM and GSRM respectively) techniques are proposed, and guidelines for selecting the radical emission bands and spatial location of photodetectors are given. Two types of experiments have been performed in order to demonstrate the reliability of the GSRM technique for combustion characterization. In the first experiment, the LSRM and the GSRM have been implemented by using a home made sensor array, based on silicon photodiodes, for sensing the excited CH* and C2 radicals in a natural gas flame. It has been experimentally that by using the GSRM, the signal’s dispersion can be reduced to about 86% for the CH* and 76% for the C2 with respect to the obtained values with LSRM methodology. In the second experiment, the GSRM technique has been applied for sensing the CH* and C2 radicals, where it has been found that the signals emissions ratio C2/CH* provides a good indicator of the thermal combustion efficiency and the CO pollutants emissions, with small dispersion. Thus, the GSRM technique has corroborated the usefulness of that ratio for combustion monitoring. [less ▲]

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See detailOn the spectrum of H II regions
Manfroid, Jean ULg

in Bulletin de l'Academie Royale de Belgique (1979), 65

It is demonstrated that the validity of present models of H II regions is not well established. It is clear that simple models (and the usual formulas involving line ratios) are unable to provide a ... [more ▼]

It is demonstrated that the validity of present models of H II regions is not well established. It is clear that simple models (and the usual formulas involving line ratios) are unable to provide a correct interpretation of the nebular spectrum. The importance of several geometrical and density effects which may account for some peculiar spectral features (such as bright forbidden S II lines and anomalous abundances) is emphasized. It is concluded that the best course to follow in H II region spectral analysis is the comparison of observations and sophisticated models on a statistical basis. [less ▲]

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See detailOn the spectrum of recombining H II regions
Manfroid, Jean ULg

in Astronomy and Astrophysics (1976), 51

The spectrum of collisionally excited lines in fossil H II regions of various densities is computed. The emission by ions of eight heavy elements is taken into account.

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See detailOn the stability of the symmetric interior penalty method - Application to 3D compressible RANS simulations of a high lift cascade flow
Drosson, Marcus ULg; Hillewaert, Koen

in ACOMEN 2011 Proceedings (2011)

Stability and convergence of the interior penalty (IP) discontinuous Galerkin method are closely related to the penalty coefficient sigma_f . Whereas Shahbazi [1] has derived nearly optimal values of ... [more ▼]

Stability and convergence of the interior penalty (IP) discontinuous Galerkin method are closely related to the penalty coefficient sigma_f . Whereas Shahbazi [1] has derived nearly optimal values of sigma_f for elliptic problems (assuming a constant viscosity parameter), we propose a generalisation of this definition, in order to take into account mesh anisotropy on the one hand, and strong variations of the diffusivity on the other hand, typical for Reynolds-averaged Navier-Stokes models, in particular the Spalart-Allmaras model. The adequacy of this new definition is illustrated by the application to benchmark 2D computations. Finally, a comparison with two state of the art finite volume solvers is presented for a 3D high-lift cascade flow. [less ▲]

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See detailOn the statistical assessment of small sample classification
Noirhomme, Quentin ULg; Lesenfants, Damien ULg; Gomez, Francisco et al

Conference (2013, December)

Classifiers start to be used in medical application to infer diagnosis. Their results are assessed through either a binomial or a permutation test. Distributions built from classification of random data ... [more ▼]

Classifiers start to be used in medical application to infer diagnosis. Their results are assessed through either a binomial or a permutation test. Distributions built from classification of random data with cross-validation, did not follow the theoretical binomial distribution, showing that binomial test was not conservative enough. A permutation test is thus recommended. [less ▲]

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See detailOn the Streptomyces albus G DD carboxypeptidase mechanism of action of penicillin, vancomycin, and ristocetin
Leyh-Bouille, Mélina; Ghuysen, Jean-Marie ULg; Nieto, Manuel et al

in Biochemistry (1970), 9(15), 2971-2975

The activity of the D-alanyl-D carboxypeptidase from the penicillin-resistant Streptomyces albus G is not or very little affected by penicillins and related antibiotics. The molecular basis for the ... [more ▼]

The activity of the D-alanyl-D carboxypeptidase from the penicillin-resistant Streptomyces albus G is not or very little affected by penicillins and related antibiotics. The molecular basis for the mechanism of action of penicillin is discussed. The Streptomyces albus G D-alanyl-D carboxypeptidase appears as a model for the study of a mechanism of penicillin resistance that does not involve the enzymatic degradation of the antibiotic. Vancomycin and ristocetin are shown to inhibit the hydrolysis of sensitive peptides by the Streptomyces albus G D-alanyl-D carboxypeptidase and the mechanism of inhibition is discussed. [less ▲]

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See detailOn the strong and selective isotope effect in the UV excitation of N2 with implications toward the nebula and Martian atmosphere
Muskatel, B. H.; Remacle, Françoise ULg; Thiemens, Mark et al

in Proceedings of the National Academy of Sciences of the United States of America (2011), 108(15), 6020-6025

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See detailOn the structural analogy between D-alanyl-D-alanine terminated peptides and β-lactam antibiotics
Brasseur, Josette ULg; Dive, Georges ULg; Ghuysen, Jean-Marie ULg

in European Journal of Medicinal Chemistry (1984), 4

Structural analogy between D-alanyl-D-alanine terminated peptides (and analogues) of varying substrate activity toward D-alanyl-D-alanine-cleaving peptidases, and bicyclic fused ring azetidinone ... [more ▼]

Structural analogy between D-alanyl-D-alanine terminated peptides (and analogues) of varying substrate activity toward D-alanyl-D-alanine-cleaving peptidases, and bicyclic fused ring azetidinone structures of varying inactivating potency toward the same enzymes has been exa-mihed by comparing the relative spatial disposition of the carboxylate function at the C-terminal position and the amide function at the N-terminal position with respect to the scissile amide bond at the central position. The observed variations in the geometric parameters and the molecular electrostatic potential maps generated by these functional groups suggest multiple modes of binding. In the monobactam sulfazecin, the relative disposition of at least the scissile amide bond and the terminal sulphamate group is comparable to that of the corresponding functions in the bicyclic β-lactams. [less ▲]

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See detailOn the structure of liquid IV-VI semiconductors
Raty, Jean-Yves ULg; Gaspard, Jean-Pierre ULg; Bionducci, M. et al

in Journal of Non-Crystalline Solids (1999), 250-252

The crystalline structure of most stoichiometric IV-VI semiconductors can be viewed as a distortion of the NaCl structure; the distortion amplitude depends on the components. As a result, corrugated ... [more ▼]

The crystalline structure of most stoichiometric IV-VI semiconductors can be viewed as a distortion of the NaCl structure; the distortion amplitude depends on the components. As a result, corrugated planes of covalently bonded atoms are linked by dispersion (Van der Waals) forces. Neutron scattering experiments were performed on the liquid phases of a series of IV-VI compounds (GeS, GeSe, GeTe, SnS, SnSe and SnTe). We show that the evolution of the local order is correlated with the conductivity measurements [less ▲]

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See detailOn the structure of liquid tellurium
Bichara, C.; Raty, Jean-Yves ULg; Gaspard, Jean-Pierre ULg

in Journal of Non-Crystalline Solids (1996), 205-207

The atomic structure and the bonding mechanism in liquid tellurium are investigated by a tight binding Monte Carlo technique. The chain structure is preserved but a third covalent bond emerges with an ... [more ▼]

The atomic structure and the bonding mechanism in liquid tellurium are investigated by a tight binding Monte Carlo technique. The chain structure is preserved but a third covalent bond emerges with an intermediate interatomic separation (3.15 Aring). In addition a bond length alternation inside the chain appears in agreement with recent EXAFS experiments and the valence angles are significantly reduced. The electronic structure is studied and particular attention is paid to the modifications of lone pair interactions in the liquid structure [less ▲]

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See detailOn the structure of the nebula M 2-9
Kohoutek, L.; Surdej, Jean ULg

in Astronomy and Astrophysics (1980), 85

The structure of planetary nebula M 2-9 has been investigated on direct plates taken with the ESO 3.6 m-telescope in 1977-78. Compared with the photographs from 1952, 1971, and 1973 the main condensations ... [more ▼]

The structure of planetary nebula M 2-9 has been investigated on direct plates taken with the ESO 3.6 m-telescope in 1977-78. Compared with the photographs from 1952, 1971, and 1973 the main condensations in the wings show a remarkable shift approximately in the W-E direction which can be explained as a rotating motion about the nebular axis of symmetry (N-S axis). The angular velocity seems to increase with the distance from the core. Two faint loops extending to about 1 arcmin on each side of the core and lying on the nebular axis were discovered. The very elongated shape of the nebula indicates the presence of an anisotropic velocity field in it. [less ▲]

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See detailOn the structure-sensitivity of 2-butanol dehydrogenation over Cu/SiO2 cogelled xerogel catalysts
Lambert, Stéphanie ULg; Cellier, Caroline; Ferauche, Fabrice et al

in Catalysis Communications (2007), 8

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See detailOn the substrate specificity of bacterial DD-peptidases: evidence from two series of peptidoglycan-mimetic peptides
Anderson, J. W.; Adediran, S. A.; Charlier, Paulette ULg et al

in Biochemical Journal (2003), 373(Part 3), 949-955

The reactions between bacterial DD-peptidases and beta-lactam antibiotics have been studied for many years. Less well understood are the interactions between these enzymes and their natural substrates ... [more ▼]

The reactions between bacterial DD-peptidases and beta-lactam antibiotics have been studied for many years. Less well understood are the interactions between these enzymes and their natural substrates, presumably the peptide moieties of peptidoglycan. In general, remarkably little activity has previously been demonstrated in vitro against potential peptide substrates, although in many cases the peptides employed were non-specific and not homologous with the relevant peptidoglycan. In this paper, the specificity of a panel of DD-peptidases against elements of species-specific D-alanyl-D-alanine peptides has been assessed. In two cases, those of soluble, low-molecular-mass DD-peptidases, high activity against the relevant peptides has been demonstrated. In these cases, the high specificity is towards the free N-terminus of the peptidoglycan fragment. With a number of other enzymes, particularly high-molecular-mass DD-peptidases, little or no activity against these peptides was observed. In separate experiments, the reactivity of the enzymes against the central, largely invariant, peptide stem was examined. None of the enzymes surveyed showed high activity against this structural element although weak specificity in the expected direction towards the one structural variable (D-gammaGln versus D-gammaGlu) was observed. The current state of understanding of the activity of these enzymes in vitro is discussed. [less ▲]

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See detailOn the symmetry of the age field of a passive tracer released into a one-dimensional fluid flow by a point-source
Deleersnijder, E.; Delhez, Eric ULg; Crucifix, M. et al

in Bulletin de la Société Royale de Liège (2001), 70

Tracer is released from a point-source into an incompressible, one-dimensional fluid flow, with constant velocity and diffusivity. The age of a tracer parcel, which is defined as the time elapsed since ... [more ▼]

Tracer is released from a point-source into an incompressible, one-dimensional fluid flow, with constant velocity and diffusivity. The age of a tracer parcel, which is defined as the time elapsed since leaving the source, may be evaluated as the ratio of the age concentration to the tracer concentration. The latter are governed by two partial differential equations. Time-dependent analytical solutions are derived, which show that the age is symmetric with respect to the source. This is astonishing, since it could have been expected that the age would reflect somehow the strong asymmetry of the tracer concentration, which tends to be much larger on the downstream side of the source than on the upstream side. Some finite-difference counterparts of this problem are seen to lead to age fields which, in their steady-state limit, are also symmetric with respect to the source. This is believed to be helpful to interpret the results of numerical models of complex fluid flows in which the age is introduced as a diagnostic variable. [less ▲]

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See detailOn the TEC short-term forecast with corrections based on the average ionospheric response to background and storm-time geomagnetic conditions
Stankov, Stanimir; Warnant, René ULg; Kozarev, R.

in Geophysical Research Abstracts (2009, April), 11(Abs. No EGU2009-13283),

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See detailOn the transferability of concepts and its significance for landscape ecology.
Bogaert, Jan ULg; Barima, Y S S

in JME : Journal of Mediterranean Ecology (2008), 9

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See detailOn the ultimate compressive strength of transversely cracked plates
Bayatfar, Abbas ULg; Pire, Timothée ULg; Rigo, Philippe ULg

in Proceedings of the ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering (2014, June)

This paper aims to numerically analyse the ultimate strength of transversely cracked steel plates under longitudinal compressive loading, considering the effect of initial distortion as well. The main ... [more ▼]

This paper aims to numerically analyse the ultimate strength of transversely cracked steel plates under longitudinal compressive loading, considering the effect of initial distortion as well. The main objective of this study is to investigate the ultimate compressive strength characteristics of an unstiffened steel plate due to transverse cracking damages located in the middle (i.e. centre cracks and edge cracks). To achieve that, a series of non-linear finite element (FE) analyses are carried out using ANSYS commercial finite element code. The obtained FE results are discussed to indicate the amount of crack influence, in terms of its length and location, on the ultimate compressive strength of a steel plate element with different thicknesses. [less ▲]

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