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See detailAn approach to modal analysis of power system angle stability
Roth, Anna; Ruiz-Vega, Daniel; Ernst, Damien ULg et al

in Proceedings of IEEE Powertech 2001 (2001)

An approach to modal analysis and modal identification is proposed, capable of complementing the panoply of existing methods. It is based on a hybrid time-domain – direct transient stability method called ... [more ▼]

An approach to modal analysis and modal identification is proposed, capable of complementing the panoply of existing methods. It is based on a hybrid time-domain – direct transient stability method called SIME (for SIngle Machine Equivalent). In short, SIME uses a conventional transient stability program to transform the time varying parameters of the system into those of a one-machine infinite bus (OMIB) equivalent system. The representations of this OMIB allow substantial reduction of the original problem’s dimensionality. Many important advantages may result. For example, the multimachine system unstable equilibrium point (UEP) can readily be derived from the OMIB UEP, which is calculated analytically and unambiguously in a two-dimensional space. Further, the interplay between multimachine and OMIB characteristics and their complementary properties provides a better understanding and handling of damping, inter-area oscillations and their control. More generally, modal analysis and modal identification tasks get closer to each other and easier to handle. The paper essentially focuses on the approach as such rather than on potential applications. Simulations carried out on a 3-machine system illustrate main features. [less ▲]

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See detailAn approach to optimise the establishment of grassy headlands in the Belgian Walloon region: A tool for agri-environmental schemes
De Longueville, Florence ULg; Tychon, Bernard ULg; Leteinturier, B. et al

in Land Use Policy (2007), 24(2), 443-450

Farming in Europe is constantly changing as environmental concerns have increasingly been taken into account since the mid 1980s and emphasis has been put on agri-environmental matters throughout all ... [more ▼]

Farming in Europe is constantly changing as environmental concerns have increasingly been taken into account since the mid 1980s and emphasis has been put on agri-environmental matters throughout all European countries. For instance, in Wallonia (Belgium), as a result of the provisions of the Government Decree on agri-environmental measures, farmers are increasingly encouraged to adopt environmentally friendly practices such as the creation of grassy headlands in their fields. As European agriculture is changing, tools are needed to monitor the evolution of agricultural practices, to control policy application and to advise farmers. In this framework, we present a new approach to optimise the establishment of grassy headlands in cultivated fields. Using a Geographic Information System (GIS), we identify exact locations where farmers can introduce grassy headlands in accordance with legal specifications and environmental concerns and calculate the total length of grassy headland that farmers can establish considering the features of their farm and parcels and for which they can receive subsidies. It indicates a potential, which could serve as a calculation baseline for an indicator. Wallonia was chosen as study area because a digitised parcel plan has been available from the Integrated Administration and Control System (IACS) since 1997. The methodological approach proposes a new valorisation of this spatial information layer and can be considered as an example of application providing relevant information for several intervention levels: national or regional decisionmakers, advisors and individual farmers. Since all EU Member States had to set up their own GIS-based land parcel system starting in 2005, our approach may be useful as is or in similar applications in other countries. (c) 2006 Elsevier Ltd. All rights reserved. [less ▲]

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See detailAn approach to real-time transient stability assessment and control
Pavella, Mania ULg; Wehenkel, Louis ULg; Bettiol, Arlon et al

in Techniques for stability limit search - Publication IEEE : TP-138-0 (1997)

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See detailAn approach to retrieve information on the carbonyl fluoride (COF2) vertical distributions above Jungfraujoch by FTIR multi-spectrum multi-window fitting
Duchatelet, Pierre ULg; Mahieu, Emmanuel ULg; Ruhnke, Roland et al

in Atmospheric Chemistry and Physics (2009), 9

We present an original multi-spectrum fitting procedure to retrieve volume mixing ratio (VMR) profiles of carbonyl fluoride (COF2) from ground-based high resolution Fourier transform infrared (FTIR) solar ... [more ▼]

We present an original multi-spectrum fitting procedure to retrieve volume mixing ratio (VMR) profiles of carbonyl fluoride (COF2) from ground-based high resolution Fourier transform infrared (FTIR) solar spectra. The multi-spectrum approach consists of simultaneously combining, during the retrievals, all spectra recorded consecutively during the same day and with the same resolution. Solar observations analyzed in this study with the SFIT-2 v3.91 fitting algorithm correspond to more than 2900 spectra recorded between January 2000 and December 2007 at high zenith angles, with a Fourier Transform Spectrometer operated at the high-altitude International Scientific Station of the Jungfraujoch (ISSJ, 46.5° N latitude, 8.0° E longitude, 3580 m altitude), Switzerland. The goal of the retrieval strategy described here is to provide information about the vertical distribution of carbonyl fluoride. The microwindows used are located in the ν4 or in the ν4 COF2 infrared (IR) absorption bands. Averaging kernel and eigenvector analysis indicates that our FTIR retrieval is sensitive to COF2 inversion between 17 and 30 km, with the major contribution to the retrieved information always coming from the measurement. Moreover, there was no significant bias between COF2 partial columns, total columns or VMR profiles retrieved from the two bands. For each wavenumber region, a complete error budget including all identified sources has been carefully established. In addition, comparisons of FTIR COF2 17–30 km partial columns with KASIMA and SLIMCAT 3-D CTMs are also presented. If we do not notice any significant bias between FTIR and SLIMCAT time series, KASIMA COF2 17–30 km partial columns are lower of around 25%, probably due to incorrect lower boundary conditions. For each times series, linear trend estimation for the 2000–2007 time period as well as a seasonal variation study are also performed and critically discussed. For FTIR and KASIMA time series, very low COF2 growth rates (0.4±0.2%/year and 0.3±0.2%/year, respectively) have been derived. However, the SLIMCAT data set gives a slight negative trend (−0.5±0.2%/year), probably ascribable to discontinuities in the meteorological data used by this model. We further demonstrate that all time series are able to reproduce the COF2 seasonal cycle, which main seasonal characteristics deduced from each data set agree quite well. [less ▲]

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See detailAN APPROACH TO THE ASYMMETRIC-SYNTHESIS OF L-6-[F-18]FLUORODOPA VIA NCA NUCLEOPHILIC FLUORINATION
Lemaire, Christian ULg; Guillaume, Marcel; Cantineau, Robert et al

in Applied Radiation & Isotopes (1991), 42(7), 629-635

The NCA asymmetric synthesis of L-6-[F-18]fluorodopa starting from (1R,2R,5R)-[(+)-2-hydroxypinanyl-3-idene]glycine t-butyl ester as chiral agent has been developed. After F-18-fluorination of the two ... [more ▼]

The NCA asymmetric synthesis of L-6-[F-18]fluorodopa starting from (1R,2R,5R)-[(+)-2-hydroxypinanyl-3-idene]glycine t-butyl ester as chiral agent has been developed. After F-18-fluorination of the two commercially available aldehydes either 6-nitroveratraldehyde or 6-nitropiperonal, the required alkylating [F-18]fluorobenzyl bromide derivative can be easily prepared by treatment with NaBH4 followed by SOBr2. Alkylation of the Schiff base was carried out with the lithium salt of 2,2,6,6-tetramethylpiperidine as base in anhydrous THF at -78-degrees-C. Following hydrolysis of the protecting groups with hydroxylamine and Hl, the L-amino acid was obtained in 75% L form (ee 50%) with a 10% decay corrected (120 min) radiochemical yield. [less ▲]

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See detailApproach to the molecular mechanisms of the modulation of growth hormone gene expression by glucocorticoid and thyroid hormones
ROUSSEAU, G. G.; ELIARD, P. H.; BARLOW, J. W. et al

in Journal of Steroid Biochemistry (1987), 27(1-3), 149-58

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See detailAn Approach to the Revenant Ballads in Newfoundland
Peere, Isabelle ULg

Conference (1986, June 02)

In continuity to our previous textual analysis of the Newfoundland corpus of Child ballads, this paper further investigates the resonance of the texts' poetic and symbolic meanings in their socio-cutlural ... [more ▼]

In continuity to our previous textual analysis of the Newfoundland corpus of Child ballads, this paper further investigates the resonance of the texts' poetic and symbolic meanings in their socio-cutlural context [less ▲]

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See detailApproach to the use of immobilizer sulfatase for analytical purposes and for the pràoduction of desulfo-glucosinolates
Wathelet, Jean-Paul ULg

in Industrial Crops & Products (1998), 7

A commercial crude sulfatase from snail (Helix pomatia) was purified by ion exchange affinity, HPLC, gel-filtration chromatography. The enzyme isolated. which was ca. 37-folcl more active than the ... [more ▼]

A commercial crude sulfatase from snail (Helix pomatia) was purified by ion exchange affinity, HPLC, gel-filtration chromatography. The enzyme isolated. which was ca. 37-folcl more active than the commercial one was covalently immobilizcd on nyon 6.6 by the cross linking method. Immobilized sulfatase was usecl to produce some desulfo-glucosinolates (DSGLs) on the gram-scale. starting fiom glucotropaeolin. glucoraphenin ancl épiprogoitrin ancl for HPLC analyses of glucosinolates (GLs) containecl in cruciferous material and rapeseecl in particular. The immobilized enzyme as well as allowing the standarclization of the HPLC methocl for GLs analysis seems to be an efflcient system for producing DSGLs which are interesting starting materials to prepare bio-active structures through further chemical modilications. [less ▲]

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See detailApproach to the use of Near Infrared Spectrometry for the estimation of microbial nitrogen contamination of forages during ruminal incubation in nylon bag.
Lecomte, Philippe; Kamoun, Mohammed; Agneessens, Richard et al

in Giesecke, D. (Ed.) Proceedings of the Society of Nutrition Physiology. (1994, September)

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See detailApproaches for assessing potential impacts of thyroid hormone disrupting chemicals in wild sea bass (Dicentrarchus labrax)
Schnitzler, Joseph ULg; Klaren, Peter; Thomé, Jean-Pierre ULg et al

Poster (2010)

Organic compounds such as pesticides and polychlorobiphenyls (PCBs) are well described endocrine disrupters; of particular interest are effects on thyroid function. To assess the ability of occurring ... [more ▼]

Organic compounds such as pesticides and polychlorobiphenyls (PCBs) are well described endocrine disrupters; of particular interest are effects on thyroid function. To assess the ability of occurring pollutants in European coastal areas to disrupt the thyroid system in sea bass, a field study in the major European estuaries, namely, the Scheldt, the Seine, the Loire, the Charente and the Garonne has been conducted. Several thyroid endpoints were simultaneously examined. Diameter of follicles and the epithelial cell heights give an indication on the production and secretion activity of the thyroid gland. The activity of enzymes involved in the metabolism (deiodination, glucuronidation and sulfatation) of thyroid hormones was analyzed. Finally thyroxine (T4) and triiodothyronine (T3) concentrations were analyzed in muscle by radioimmunoassay. The combined use of all those endpoints gives us an overview of the complex thyroid hormone system. PCB concentration in wild fish varied from 10 to 100 ng g-1 wet weight (ww) depending on length and location. Each region has its own contamination levels and profiles reflecting the contribution of pollutants from rivers. The contamination levels were as follows: the highest concentrations were measured in individuals collected from the coastal region near the Scheldt > Seine > Loire > Charente and the lowest levels were observed in sea bass from coastal regions near the Garonne. Measurements of metabolic activity revealed an altered hepatic T4 outer ring deiodinase whereas T4 sulfatation and T4 glucuronidation were not affected. Owing to the extensive autoregulatory feedback at both central and peripheral levels, the thyroid hormone concentrations were preserved despite the PCB induced changes in thyroid hormone dynamics. [less ▲]

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See detailApproaches for assessing the presence and impact of thyroid hormone disrupting chemicals in sea bass (Dicentrarchus labrax) from European coasts
Schnitzler, Joseph ULg

Doctoral thesis (2011)

Thyroid functional status of wild fish in relation with the contamination of their environment deserves further investigation. Polychlorinated biphenyls (PCBs) and organochlorine pesticides like Dichloro ... [more ▼]

Thyroid functional status of wild fish in relation with the contamination of their environment deserves further investigation. Polychlorinated biphenyls (PCBs) and organochlorine pesticides like Dichloro-Diphenyl-Trichloroethane (DDTs), Hexachlorocyclohexanes (HCHs), aldrin, dieldrin and trace elements (Cd, Cu, Se, Pb, Zn and Hg) were analysed in the muscle of sea bass (Dicentrarchus labrax) sampled in coastal regions near several important European river mouths (Gironde, Charente, Loire, Seine and Scheldt). We applied a multi-level approach of thyroid function assessment. Thyroxine (T4) and triiodothyronine (T3) concentrations in muscle were analyzed by radioimmunoassay. The activity of hepatic enzymes involved in extrathyroidal pathways of thyroid hormone metabolism, viz. deiodination, glucuronidation and sulfation were analyzed. Last, follicle diameter and epithelial cell heights were measured. We observed changes that lead to an increased conversion of T4 to T3 and lowered thyroid hormone excretion. The changes in the metabolic pathways of thyroid hormones can be interpreted as a pathway to maintain thyroid hormone homeostasis. The higher chlorinated PCBs seemed to be the most implicated in this perturbation. To gain a more integrated insight, we examined the effect of subchronic exposure to a mixture of Aroclor standards on thyroid hormone physiology and metabolism in juvenile sea bass. After 120 days of exposure, histomorphometry of thyroid tissue, muscular thyroid hormone concentration and activity of enzymes involved in metabolism of thyroid hormones were assessed. The results show that the effects of PCB exposures on the thyroid system are dose-dependent. Exposure to environmentally relevant doses of PCB (0.3 to 1.0 μg Σ7PCBs per g food pellets) increases thyroid hormone synthesis and stimulates hepatic T4 outer ring deiodinase and T4 sulfation. Thyroid hormone tissue levels were preserved thanks to the PCB induced changes in T4 dynamics. At 10 times higher concentrations (10 μg Σ7PCBs per g food pellets) an important depression of T3 and T4 levels could be observed which are apparently caused by degenerative histological changes in the thyroid tissue. We propose accurate interpretations, by reviewing the different stages of teleost thyroid function and regulation. [less ▲]

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See detailApproaches for retrieving abundances of methane isotopologues in the frame of the AGACC project from ground-based FTIR observations performed at the Jungfraujoch
Duchatelet, Pierre ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

Poster (2007, April)

This work has been performed within the frame of AGACC(http://www.oma.be/AGACC/Home.html), a contribution to the Belgian Scientific Support for a Sustainable Development. The project intends to make an ... [more ▼]

This work has been performed within the frame of AGACC(http://www.oma.be/AGACC/Home.html), a contribution to the Belgian Scientific Support for a Sustainable Development. The project intends to make an advanced exploitation of existing ground-based remote-sensing measurements for a selection of atmospheric species that play an important role in the chemistry of the atmosphere and that have a direct or indirect impact on climate. Target species include -among others- lower tropospheric aerosols, H2O, HDO, CH4, HCN and CO. The instrumentation includes 3 types of spectrometers (FTIR, MAXDOAS and Brewer) and one CIMEL sun photometer. These instruments are operated at 3 different sites (Jungfraujoch, Ile de la Réunion and Uccle) and most of them are affiliated with the Network for the Detection of Atmospheric Composition Change (NDACC, formerly NDSC - http://www.ndacc.org), a group dedicated to performing high-quality long-term observations. This contribution will deal with the detection of the isotopologues of methane, a species released to the atmosphere by natural processes (e.g. wetlands, termites) as well as by anthropogenic activities (e.g. fossil fuel exploitation, rice agriculture, biomass burning, etc). Due to its high warming potential and its relatively long chemical lifetime, atmospheric methane is a major greenhouse gas. Methane also affects climate by influencing tropospheric ozone and stratospheric water. The cycle of methane is complex and a thoroughly study of the sources and sinks of its main isotopologue, as well as the other isotopic species, is necessary to characterize it. Isotopic ratios are also useful to differentiate between various sources of atmospheric methane. To study the vertical distribution of methane isotopologues from the high resolution FTIR spectra recorded by the University of Liège instrument at the International Scientific Station of the Jungfraujoch (ISSJ; 46.5°N, 8.0°E, 3580m a.s.l., Swiss Alps), we have selected several 13CH4 lines distributed in the so-called InSb (1-5 µm) and MCT (2-16 µm) spectral ranges. A set of four microwindows has also been selected for the study of CH3D. Using the SFIT-2 v3.91 algorithm, vertical column abundances as well as low-resolution vertical distributions have been retrieved, adjusted from an a priori profile defined on a 41 layers scheme and derived from ACE-FTS space observations. The information content and first preliminary retrieval results will be presented. [less ▲]

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See detailApproaches of organizational effectiveness applied to social enterprises
Mouchamps, Hugues ULg

Conference (2013, October 25)

This speech aims to address two theoretical challenges to which every scholar interested in the performance of social enterprises is confronted: the problem of defining what performance exactly is and the ... [more ▼]

This speech aims to address two theoretical challenges to which every scholar interested in the performance of social enterprises is confronted: the problem of defining what performance exactly is and the integration of the complexity inherent to social enterprises in the definition of performance (Speckbacher, 2003; Meadows and Pike, 2010; Samples and Austin, 2009; Polonsky and Grau, 2008). Our point is that the performance literature does not currently provide satisfying answers to these challenges. The first challenge identified is the confusion in the literature surrounding the definition of organizational performance (Quinn & Rohrbaugh, 1983). Performance scholars contributed to this confusion by each using an own definition of performance unrelated to any wider theoretical framework or by even bypassing the definition issue (Campbell, 1977). As they rarely share common definitions of performance, the accumulation of a body of common knowledge remains illusionary. In any case, performance scholars stick to isolated definitions and hardly recognize that multiple contingent definitions of performance can coexist in a consistent framework. The second challenge is closely related to the first one as it also concerns the definition of performance. For social enterprises, the performance definition step is an essential issue because, unlike for-profit corporations often do, relying only on straightforward performance indicators such as financial ratios would not be sufficient. Therefore they have to work on with a more complex definition of performance, which forces them to deepen the definition issue even more carefully. These challenges are addressed in the two sections of this paper. The first challenge is tackled in the first section of the paper, in which we compare the relative advantages of two bodies of literature likely to serve as basis for the definition of performance for social enterprises. This first section concludes with the relevance of rejuvenating an old body of literature, namely “organizational effectiveness” , which is likely to provide answers to the confusion plaguing the definition issue in the performance literature. Based on that theoretical finding, we develop a second section in which we review the OE literature to deal with the second challenge. This body of literature can potentially offer strong theoretical bases to integrate the complexity of social enterprises, except that the interrelationships between the existing OE approaches have never been explicitly stressed up to now. Therefore we address this research gap by setting up a framework articulating the existing OE approaches, which can open the way to integrate the complexity of social enterprises. [less ▲]

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See detailApproaches to handling incomplete data in family-based association testing
Van Steen, Kristel ULg; Laird, N. M.; Markel, P. et al

in Annals of Human Genetics (2007), 71(Pt 2), 141-51

The high throughput of data arising from the complete sequence of the human genome has left statistical geneticists with a rich and extensive information source. The wide availability of software and the ... [more ▼]

The high throughput of data arising from the complete sequence of the human genome has left statistical geneticists with a rich and extensive information source. The wide availability of software and the increase in computing power has improved the possibilities to access and process such data. One problem is incompleteness of the data: unobserved or partially observed data points due to technical reasons or reasons associated with the patient's status or erroneous measurements of phenotype or genotype, to name a few. When not properly accounted for, these sources of incompleteness may seriously jeopardize the credibility of results from analyses. In this paper we provide some perspectives on the occurrence and analysis of different forms of incomplete data in family-based genetic association testing. [less ▲]

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See detailApproaches to synthesize carbon-supported platinum-based electrocatalysts for proton-exchange membrane fuel cells
Maillard, Frédéric; Job, Nathalie ULg; Chatenet, Marian

in Suib, Steven (Ed.) New and future developments in catalysis. Batteries, hydrogen storage and fuel cells (2013)

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See detailApproaches to the optimal navigation organization on the inland waterway network
Marchal, Jean ULg; Zhang, Z. M.

in Procceedings of the First Symposium on Operation Research with Application in Engineering, Technology and Management (ISORA’95) (1995)

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See detailApproaches to unravel the pathophysiological background of unexplained perinatal mortality in dairy cows
Taverne, M. A. M.; van der Weijden, G. C.; Jonker, F. H. et al

in Reproduction in Domestic Animals (2007), 42(Suppl. 2), 64

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See detailApproaching field tuned quantum criticality in CeIn3-xSnx
Silhanek, Alejandro ULg; Zocco, D.; Harrison, N. et al

in Physica B: Condensed Matter (2006), 378-80

We report on the magnetic field evolution of the Neel temperature T-N in the heavy electron system CeIn3-xSnx (x = 0 and 0.3), as determined by specific heat, magnetocaloric effect, and electrical ... [more ▼]

We report on the magnetic field evolution of the Neel temperature T-N in the heavy electron system CeIn3-xSnx (x = 0 and 0.3), as determined by specific heat, magnetocaloric effect, and electrical transport measurements. For the stoichiometric compound, T-N is fully suppressed at H-c similar to 65 T, whereas for x = 0.3 the critical field extrapolates to H-c similar to 30 T. An increasing Sommerfeld coefficient gamma, obtained above T-N, as field increases is observed and could be related to the a putative quantum critical point at H-c. (c) 2006 Published by Elsevier B.V. [less ▲]

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See detailApproaching the true prevalence of pituitary tumors
Beckers, Albert ULg; Adam, C.; Ciccarelli, A. et al

in ENEA congress : Napoli, April 2004 (2004, April)

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