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See detailAn Improved Reachability Analysis Method for Strongly Linear Hybrid Systems
Boigelot, Bernard ULiege; Bronne, Louis; Rassart, Stéphane

in Lecture Notes in Computer Science (1997), 1254

This paper addresses the exact computation of the set of reachable states of a linear hybrid system. It proposes an approach that is an extension of classical state-space exploration. This approach uses a ... [more ▼]

This paper addresses the exact computation of the set of reachable states of a linear hybrid system. It proposes an approach that is an extension of classical state-space exploration. This approach uses a new operation, based on a cycle analysis in the control graph of the system, for generating sets of reachable states, as well as a powerful representation system for sets of values. The method broadens the range of hybrid systems for which a finite and exact representation of the set of reachable states can be computed. In particular, the state-space exploration may be performed even if the set of variable values reachable at a given control location cannot be expressed as a finite union of convex regions. The technique is illustrated on a very simple example. [less ▲]

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See detailImproved separation and quantification of dioxin and furan congeners using Novel low-bleed capillary gas chromatography columns and mass spectrometry
Dorman, Frank; Reese, Shawn; Reiner, Eric et al

in Organohalogen Compounds (2004), 66

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See detailImproved separation of the 209 PCBs using GCxGC-TOFMS
Focant, Jean-François ULiege; Sjödin, Andreas; Patterson, Donald G.

in Organohalogen Compounds (2004), 66

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See detailImproved separation of the 209 polychlorinated biphenyl congeners using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry
Focant, Jean-François ULiege; Sjödin, Andreas; Patterson, Donald G.

in Journal of Chromatography. A (2004), 1040(2), 227-238

The separation of the 209 polychlorinated biphenyl (PCB) congeners has been studied using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC x GC-TOFMS). Four ... [more ▼]

The separation of the 209 polychlorinated biphenyl (PCB) congeners has been studied using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC x GC-TOFMS). Four column combinations based on thermally stable phases, DB-1/HT-8, DB-XLB/HT-8, DB-XLB/BPX-50, and HT-8/BPX-50, have been investigated. The HT-8/BPX-50 set produced the best separation. The distribution of the 100 to 150 ms wide peaks was highly structured in the chromatographic space and based on the degree of ortho-substitution within each separated homologue series. A total of 192 congeners were resolved in 146 min (1.3 analyte per min) using this column set. Eight coelutions involved 17 congeners. Among them, seven congeners were present in Aroclors at levels >1.0 wt.% (CBs 33, 47, 48, 95, 97, 163, 187). Except for CBs 47 and 48, none of the major constituents of commercial mixtures were coeluting. CB 138 was well separated from CBs 163 and 164 in the second dimension. For all column sets, CBs 20, 33, and 109 always coeluted with other PCBs. The 12 toxic dioxin-like congeners (CBs 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, 189), and the seven European Union marker PCBs (CBs 28, 52, 101, 118, 138, 153, 180) were separated from any interfering congeners. This was not the case for the other investigated column sets. [less ▲]

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See detailImproved shimming for fMRI specifically optimizing the local BOLD sensitivity
Balteau, Evelyne ULiege; Hutton, Chloe; Weiskopf, Nikolaus

in NeuroImage (2010), 49

In functional MRI, magnetic field inhomogeneities due to air-tissue susceptibility differences may lead to severe signal dropouts and geometric distortions in echo-planar images. Therefore, the ... [more ▼]

In functional MRI, magnetic field inhomogeneities due to air-tissue susceptibility differences may lead to severe signal dropouts and geometric distortions in echo-planar images. Therefore, the inhomogeneities in the field are routinely minimized by shimming prior to imaging. However in fMRI, the Blood Oxygen Level Dependent (BOLD) effect is the measure of interest, so the BOLD sensitivity (BS) should be optimized rather than the magnetic field homogeneity. The analytical expression for an estimate of the BOLD sensitivity has been recently developed, allowing for the computation of BOLD sensitivity maps from echo-planar images and field maps. This report describes a novel shimming procedure that optimizes the local BOLD sensitivity over a region of interest. The method is applied in vivo and compared to a standard global shimming procedure. A breath-holding experiment was carried out and demonstrated that the BS-based shimming significantly improved the detection of activation in a target region of interest, the medial orbitofrontal cortex. [less ▲]

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See detailImproved spectral fitting of nitrogen dioxide from OMI in the 405-465 nm window
van Geffen, J H G M; Boersma, K F; Van Roozendael, M et al

in Atmospheric Measurement Techniques (2015), 8

An improved nitrogen dioxide (NO2) slant column density retrieval for the Ozone Monitoring Instrument (OMI) in the 405–465 nm spectral region is presented. Since the launch of OMI on board NASA’s EOS-Aura ... [more ▼]

An improved nitrogen dioxide (NO2) slant column density retrieval for the Ozone Monitoring Instrument (OMI) in the 405–465 nm spectral region is presented. Since the launch of OMI on board NASA’s EOS-Aura satellite in 2004, differential optical absorption spectroscopy (DOAS) retrievals of NO2 slant column densities have been the starting point for the KNMI DOMINO and NASA SP NO2 vertical column data as well as the OMI NO2 data of some other institutes. However, recent intercomparisons between NO2 retrievals from OMI and other UV/Vis and limb spectrometers, as well as ground-based measurements, suggest that OMI stratospheric NO2 is biased high. This study revises and, for the first time, fully documents the OMI NO2 retrieval in detail. The representation of the OMI slit function to convolve high-resolution reference spectra onto the relevant spectral grid is improved. The window used for the wavelength calibration is optimised, leading to much-reduced fitting errors. Ozone and water vapour spectra used in the fit are updated, reflecting the recently improved knowledge of their absorption cross section in the literature. The improved spectral fit also accounts for absorption by the O2–O2 collision complex and by liquid water over clearwater areas. The main changes in the improved spectral fitting result from the updates related to the wavelength calibration: the RMS error of the fit is reduced by 23% and the NO2 slant column by 0.85 1015 molec cm-2, independent of latitude, solar zenith angle and NO2 value. Including O2–O2 and liquid water absorption and updating the O3 and water vapour cross-section spectra further reduces NO2 slant columns on average by 0.35 1015 molec cm-2, accompanied by a further 9% reduction in the RMS error of the fit. The improved OMI NO2 slant columns are consistent with independent NO2 retrievals from other instruments to within a range that can be explained by photochemically driven diurnal increases in stratospheric NO2 and by small differences in fitting window and approach. The revisions indicate that current OMI NO2 slant columns suffered mostly from an additive positive offset, which is removed by the improved wavelength calibration and representation of the OMI slit function. It is therefore anticipated that the improved NO2 slant columns are most important to retrievals of spatially homogeneous stratospheric NO2 rather than to heterogeneous tropospheric NO2. [less ▲]

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See detailImproved spectral parameters for the 16O2 infrared forbidden lines in the X3∑g− (0–1) band
Goldman, A.; Rinsland, C. P.; Canova, B. et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (1995), 54(5), 757-765

New spectral parameters have been generated for the electric quadrupole (eq) and magnetic dipole (md) infrared transitions in the fundamental vibration-rotation 3∑g− (0–1) band of 16O2. Significant ... [more ▼]

New spectral parameters have been generated for the electric quadrupole (eq) and magnetic dipole (md) infrared transitions in the fundamental vibration-rotation 3∑g− (0–1) band of 16O2. Significant improvements in line positions (for both eq and md) and in the long standing problem of the md line intensities, have been achieved by combining recent theoretical work with the analysis of high resolution (0.002 and 0.01 cm−1) solar absorption spectra. [less ▲]

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See detailImproved stability and transient behaviour of generalized-alpha time integrators for constrained flexible systems
Arnold, Martin; Bruls, Olivier ULiege; Cardona, Alberto

Conference (2011, November)

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See detailImproved statistics of submesoscale eddies in the Baltic Sea retrieved from SAR imagery
Karimova, Svetlana ULiege; Gade, Martin

in International Journal of Remote Sensing (2016), 37(10), 2394-2414

In the present paper the spatio-temporal distribution of submesoscale eddies seen in Envisat Advanced Synthetic Aperture Radar (ASAR) imagery of the Baltic Sea is discussed. A total of 1250 ASAR images ... [more ▼]

In the present paper the spatio-temporal distribution of submesoscale eddies seen in Envisat Advanced Synthetic Aperture Radar (ASAR) imagery of the Baltic Sea is discussed. A total of 1250 ASAR images acquired between 2009 and 2011 form the basis of our studies and show imprints of almost 7000 submesoscale eddies. Since the visibility of vortical structures in synthetic aperture radar (SAR) imagery significantly depends on the near-surface wind speed, wind data from a numerical model of the Baltic Sea were additionally used to get improved eddy statistics. Seasonally averaged fields of near-surface wind speed, surface currents, sea surface temperature (SST), and SST gradient were also analyzed in order to reveal the role of these hydrophysical parameters in the observed spatial and temporal variation of submesoscale eddies. [less ▲]

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See detailImproved surface quality of anisotropically etched silicon {111} planes for mm-scale integrated optics
Cotter, J. P.; Zeimpekis, Ioannis; Kraft, Michaël ULiege et al

in Journal of Micromechanics and Microengineering (2013), 23(11), 117006

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See detailAn improved synthesis of 9-[(3)-[F-18]fluoro-1-hydroxy-2-propoxy)methyl]guanine ([F-18]FHPG).
SHIUE, CY.; SHIUE, GG.; HUSTINX, Roland ULiege et al

in Journal of Nuclear Medicine (The) (1999), 40

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See detailAn improved technique for the preparation of Streptomyces peptidases and N-acetylmuramyl-l-alanine amidase active on bacterial wall peptidoglycans
Ghuysen, Jean-Marie ULiege; Dierickx, L.; Coyette, J. et al

in Biochemistry (1969), 8(1), 213-222

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See detailAn Improved Test to Study the Changes in Membrane Permeability During Rehydration of Freeze-Dried Weissella paramesenteroides LC11
Soro, Amenan Anastasie; Djè, K. M.; Thonart, Philippe ULiege

in The Open Biotechnology Journal (2010), 4

The objective of this study was to assess changes in membrane permeability during rehydration of freeze-dried Weissella paramesenteroides LC11. Viability was assessed using the electrical conductivity ... [more ▼]

The objective of this study was to assess changes in membrane permeability during rehydration of freeze-dried Weissella paramesenteroides LC11. Viability was assessed using the electrical conductivity measurement (ms cm-1 g-1 dry weight) and the plate count method (cfu g-1 dry weight). The symptoms of injury included an increase in the electrolyte leakage during the first 4 h of rehydration in Milli Q water and a decrease in the survival rate (about 64%), suggesting an increase in membrane permeability during dehydration. During rehydration of the freeze-dried strain, an increase in the temperature, NaCl or monosodium glutamate concentration and a decrease in H+ concentration resulted in an increase in the electrolyte leakage and a decrease in the survival rate (from about 5% to 97%, with respect to the treatment made). However, a decrease in the electrolyte leakage was observed with increasing glycerol, sucrose or maltodextrin and resulted in the maintenance of cell viability. Change in membrane permeability might lead to electrolyte leakage during rehydration and, ultimately, cell death. The electrolyte leakage assay associated with the plate count method, a quick and inexpensive method, could be used to evaluate dried bacteria resistance to dehydration. [less ▲]

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See detailImproved Thévenin equivalent methods for real-time voltage stability assessment
Perez, Angel; Johannsson, Hjortur; Ostergaard, Jacob et al

in proc. IEEE ENERGYCON Conference (2016, April)

An improved Thévenin equivalent method for real-time voltage stability assessment that uses wide-area information from synchrophasors is proposed. The improvements are a better modeling of the limited ... [more ▼]

An improved Thévenin equivalent method for real-time voltage stability assessment that uses wide-area information from synchrophasors is proposed. The improvements are a better modeling of the limited synchronous generators, and a processing that anticipates the effect of field current limiters, before the latter are activated. Several study cases using detailed dynamic simulations of the Nordic test system have been used to assess the performance of the proposed improvements. Their effectiveness is analyzed and, based on the results, their possible application in combination with the sensitivity-based voltage stability assessment method is explored. [less ▲]

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See detailImproved use of serial laboratory data in acute myocardial infarction
Albert, Adelin ULiege; Chapelle, Jean-Paul ULiege; Heusghem, C. et al

Poster (1982, August)

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See detailImproved use of serial laboratory data in acute myocardial infarction
Albert, Adelin ULiege; Chapelle, Jean-Paul ULiege; Heusghem, C. et al

in Clinical Chemistry (1983), 28

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See detailImproved vitrification method allowing direct transfer of goat embryos
Guignot, F.; Bouttier, A.; Baril, G. et al

in Theriogenology (2006), 66(4), 1004-1011

The aim of this study was to design a vitrification method suited to field embryo transfer experiments in goat. In a first experiment, a standard vitrification protocol, previously designed for sheep ... [more ▼]

The aim of this study was to design a vitrification method suited to field embryo transfer experiments in goat. In a first experiment, a standard vitrification protocol, previously designed for sheep embryos was compared to slow freezing of goat embryos. No significant difference was observed on kidding rate (48% versus 69%, respectively), nor on embryo survival rate (35% versus 45%). Second experiment: all embryos were vitrified. After warming, embryos were either transferred directly (direct transfer), or after in vitro dilution of the cryoprotectants (conventional transfer). The kidding rate was not affected by the transfer method (38% versus 23%, respectively). However, embryo survival rate tended to be higher after direct transfer (26% versus 14%). Third experiment: OPS vitrification was compared to standard vitrification. The kidding rate was not affected (22% versus 39%, respectively), but the embryo survival rate was lower after OPS (14% versus 28%). Fourth experiment: 0.4 M sucrose was added with cryoprotectants in vitrification. The kidding rate after direct transfer was significantly enhanced after addition of sucrose (56% versus 27%, respectively), whereas embryo survival rate was not significantly affected (32% versus 18%). Fifth experiment: vitrification with sucrose supplementation was compared to slow freezing. No significant difference was observed after direct transfer on kidding rate (52% versus 31%, respectively), but embryo survival rate tended to be higher after vitrification (34% versus 2 1 %). In conclusion, our results indicate that addition of 0.4 M sucrose in association with direct transfer improves significantly the viability of goat vitrified embryos. [less ▲]

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See detailAn improved weighting method with multibounds formulation and convex programming for multicriteria structural optimization
Zhang, W. H.; Domaszewski, M.; Fleury, Claude ULiege

in International Journal for Numerical Methods in Engineering (2001), 52(9), 889-902

This paper presents an improved weighting method for multicriteria structural optimization. By introducing artificial design variables, here called as multibounds formulation (MBF), we demonstrate ... [more ▼]

This paper presents an improved weighting method for multicriteria structural optimization. By introducing artificial design variables, here called as multibounds formulation (MBF), we demonstrate mathematically that the weighting combination of criteria can be transformed into a simplified problem with a linear objective function. This is a unified formulation for one criterion and multicriteria problems. Due to the uncoupling of involved criteria after the transformation, the extension and the adaptation of monotonic approximation-based convex programming methods such as the convex linearization (CONLIN) or the method of moving asymptotes (MMA)are made possible to solve multicriteria problems as efficiently as for one criterion problems. In this work, a multicriteria optimization tool is developed by integrating the multibounds formulation with the CONLIN optimizer and the ABAQUS finite element analysis system. Some numerical examples are taken into account to show the efficiency of this approach. [less ▲]

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See detailImprovement and validation of milk fatty acid predictions using mid-infrared spectrometry
Soyeurt, Hélène ULiege; McParland, Sinead; Berry, Donagh et al

in Proceedings of the Bristish Society of Animal Science and the Agricultural Research Forum (2010)

Detailed reference viewed: 38 (6 ULiège)