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See detailAn Improved On-line Contingency Screening for Power System Transient Stability Assessment
Weckesser, Johannes ULg; Jóhannsson, Hjörtur; Glavic, Mevludin ULg et al

in Electric Power Components & Systems (2017)

This paper presents a contingency screening method and a framework for its on-line implementation. The proposed method carries out contingency screening and on-line stability assessment with respect to ... [more ▼]

This paper presents a contingency screening method and a framework for its on-line implementation. The proposed method carries out contingency screening and on-line stability assessment with respect to first-swing transient stability. For that purpose, it utilizes the single machine equivalent method and aims at improving the prior developed contingency screening approaches. In order to determine vulnerability of the system with respect to a particular contingency, only one time-domain simulation needs to be performed. An early stop criteria is proposed so that in a majority of the cases the simulation can be terminated after a few hundred milliseconds of simulated system response. The method’s outcome is an assessment of the system’s stability and a classification of each considered contingency. The contingencies are categorized by exploiting parameters of an equivalent one machine infinite bus system. A novel island detection approach, appropriate for an on-line application since it utilizes efficient algorithms from graph theory and enables stability assessment of individual islands, is also introduced. The New England and New York system as well as the large-scale model of the Continental-European interconnected system are used to test the proposed method with respect to assessment accuracy and computation time. [less ▲]

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See detailImproved one-dimensional numerical simulation of transient mixed flow in water pipes network
Kerger, François ULg; Archambeau, Pierre ULg; Erpicum, Sébastien ULg et al

in Proceedings of the 2nd ENVITAM PhD Day (2008, January 29)

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See detailAN IMPROVED ONE-POINT INTEGRATION METHOD FOR LARGE-STRAIN ELASTOPLASTIC ANALYSIS
Stainier, Laurent ULg; Ponthot, Jean-Philippe ULg

in Computer Methods in Applied Mechanics & Engineering (1994), 118(1-2), 163-177

In this paper, we present a new one-point integration method generalizing Flanagan and Belytschko's method (Internat. J. Numer. Methods Engrg. 17 (1981) 679-706) and a modification of Belytschko and ... [more ▼]

In this paper, we present a new one-point integration method generalizing Flanagan and Belytschko's method (Internat. J. Numer. Methods Engrg. 17 (1981) 679-706) and a modification of Belytschko and Bindeman's method (Comput. Methods Appl. Mech. Engrg. 88 (1991) 311-340), both in the frame of large deformation elastoplastic analysis. These stabilization methods are combined with the radial return method used to integrate the constitutive law. Plane strain problems are first considered, and the method is then generalized to axisymmetrical situations. The explicit time integration scheme with its critical timestep is also considered. A few examples are presented that show the great time savings that can be obtained with reduced integration without any loss of accuracy, and even with a gain in the solution quality, since the underintegrated elements prove to be 'flexurally superconvergent'. [less ▲]

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See detailImproved operational model for real-time reconstruction of the electron density profile at a single ionosonde location
Stankov, Stanimir; Warnant, René ULg; Jodogne, Jean-Claude

in Proceedings of the COST271 2002 workshop (2002, October)

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See detailImproved Outcome Prediction Based on Csf Extrapolated Creatine Kinase Bb Isoenzyme Activity and Other Risk Factors in Severe Head Injury
Hans, Pol ULg; Albert, Adelin ULg; FRANSSEN, Colette ULg et al

in Journal of Neurosurgery (1989), 71(1), 54-8

The present study of 43 patients with severe head injury shows that outcome prediction can be markedly improved by combining an appropriate marker of the degree of initial brain damage and other risk ... [more ▼]

The present study of 43 patients with severe head injury shows that outcome prediction can be markedly improved by combining an appropriate marker of the degree of initial brain damage and other risk factors. The patients were classified into three groups according to their actual outcome after 6 months: death (22 patients); persistent vegetative state or severe disability (eight patients); and moderate disability or good recovery (13 patients). By applying stepwise logistic discriminant analysis to the patients' data, five significant risk factors were selected: degree of neurological damage assessed by cerebrospinal fluid (CSF) extrapolated creatine kinase BB isoenzyme activity, Glasgow-Liege Coma Scale score, age, incidence of thoracic injury, and intracranial pressure (ICP). Extrapolated creatine kinase BB activity had the highest prognostic ability (67%). Uncontrollable elevated ICP proved to be systematically associated with death, whereas its absence was not necessarily indicative of a favorable outcome. The combination of the five variables yielded a total prognostic efficiency of 91%. The percentages of correctly predicted patients for the three outcome groups were, respectively, 100%, 50%, and 100%. Thus, half of the persistently vegetative and severely disabled patients were identified by the selected factors. [less ▲]

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See detailImproved pancreatic K-ATP channel openers belonging to the pyridothiadiazine chemical class
Pirotte, Bernard ULg; De Tullio, Pascal ULg; Lebrun, P. et al

in Journal de Pharmacie de Belgique (1993), 48

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See detailImproved parallelism and scheduling in multi-core software routers
Egi, Norbert; Iannaccone, Gianluca; Manesh, Maziar et al

in Journal of Supercomputing (2011)

Recent technological advances in commodity server architectures, with multiple multi-core CPUs, integrated memory controllers, high-speed interconnects, and enhanced network interface cards, provide ... [more ▼]

Recent technological advances in commodity server architectures, with multiple multi-core CPUs, integrated memory controllers, high-speed interconnects, and enhanced network interface cards, provide substantial computational capacity, and thus an attractive platform for packet forwarding. However, to exploit this available capacity, we need a suitable software platform that allows effective parallel packet processing and resource management. In this paper, we at first introduce an improved forwarding architecture for software routers that enhances parallelism by exploiting hardware classification and multi-queue support, already available in recent commodity network interface cards. After evaluating the original scheduling algorithm of the widely-used Click modular router, we propose solutions for extending this scheduler for improved fairness, throughput, and more precise resource management. To illustrate the potential benefits of our proposal, we implement and evaluate a few key elements of our overall design. Finally, we discuss how our improved forwarding architecture and resource management might be applied in virtualized software routers. [less ▲]

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See detailImproved parameters for the transiting hot Jupiters WASP-4b and WASP-5b
Gillon, Michaël ULg; Smalley, B.; Hebb, L. et al

in Astronomy and Astrophysics (2009), 496

The gaseous giant planets WASP-4b and WASP-5b are transiting 12-magnitude solar-type stars in the Southern hemisphere. The aim of the present work is to refine the parameters of these systems using high ... [more ▼]

The gaseous giant planets WASP-4b and WASP-5b are transiting 12-magnitude solar-type stars in the Southern hemisphere. The aim of the present work is to refine the parameters of these systems using high cadence VLT/FORS2 z-band transit photometry and high-resolution VLT/UVES spectroscopy. For WASP-4, the new estimates for the planet radius and mass from a combined analysis of our VLT data with previously published transit photometry and radial velocities are R[SUB]p[/SUB] = 1.30[SUP]+0.05[/SUP][SUB]-0.04[/SUB] R[SUB]J[/SUB] and M[SUB]p[/SUB] = 1.21[SUP]+0.13[/SUP][SUB]-0.08[/SUB] M_J, resulting in a density rho[SUB]p[/SUB] = 0.55[SUP]+0.04[/SUP][SUB]-0.02[/SUB] rho_J. The radius and mass for the host star are R_* = 0.87[SUP]+0.04[/SUP][SUB]-0.03[/SUB] R_o and M_* = 0.85[SUP]+0.11[/SUP][SUB]-0.07[/SUB] M_o. Our ground-based photometry reaches 550 ppm at time sampling of ~50 s. Nevertheless, we also report the presence of an instrumental effect on the VLT that degraded our photometry for the WASP-5 observations. This effect could be a major problem for similar programs. Our new estimates for the parameters of the WASP-5 system are R[SUB]p[/SUB] = 1.09 ± 0.07 R_J, M[SUB]p[/SUB] = 1.58[SUP]+0.13[/SUP][SUB]-0.10[/SUB] M_J, rho[SUB]p[/SUB] = 1.23 [SUP]+0.26[/SUP][SUB]-0.16[/SUB] rho_J, R_* = 1.03[SUP]+0.06[/SUP][SUB]-0.07[/SUB] R_o, and M_* = 0.96[SUP]+0.13[/SUP][SUB]-0.09[/SUB] M_o. The measured size of WASP-5b agrees well with the basic models of irradiated planets, while WASP-4b is clearly an ``anomalously'' large planet. Based on data collected with the FORS2 imager at the VLT-UT4 telescope and with the UVES spectrograph at the VLT-UT2 telescope (Paranal Observatory, ESO, Chile) in the programme 280.C-5003. [less ▲]

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See detailImproved parameters for the transiting planet HD 17156b: a high-density giant planet with a very eccentric orbit
Gillon, Michaël ULg; Triaud, A H M J; Mayor, M. et al

in Astronomy and Astrophysics (2008), 485

We report high-precision transit photometry for the recently detected planet HD 17156b. Using these new data with previously published transit photometry and radial velocity measurements, we perform a ... [more ▼]

We report high-precision transit photometry for the recently detected planet HD 17156b. Using these new data with previously published transit photometry and radial velocity measurements, we perform a combined analysis based on a Markov Chain Monte Carlo approach. The resulting mass M[SUB]p[/SUB] = 3.09[SUP]+0.22[/SUP][SUB]-0.17[/SUB]~M_Jup and radius R[SUB]p[/SUB] = 1.23[SUP]+0.17[/SUP][SUB]-0.20[/SUB] R_Jup for the planet places it at the outer edge of the density distribution of known transiting planets with rho[SUB]p[/SUB] = 1.66[SUP]+1.37[/SUP][SUB]-0.60[/SUB] rho_Jup. The obtained transit ephemeris is T_Tr = 2 454 438.48271[SUP]+0.00077[/SUP][SUB]-0.00057[/SUB] + N × 21.21747[SUP]+0.00070[/SUP][SUB]-0.00067[/SUB] BJD. The derived plausible tidal circularization time scales for HD 17156b are larger than the age of the host star. The measured high orbital eccentricity e = 0.6719[SUP]+0.0052[/SUP][SUB]-0.0063[/SUB] can thus not be interpreted as the clear sign of the presence of another body in the system. Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. Photometric measurements are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/485/871 [less ▲]

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See detailImproved performances of intraocular lenses by poly(ethylene glycol) chemical coatings
Bozukova, Dimitriya ULg; Pagnoulle, Christophe; De Pauw-Gillet, Marie-Claire ULg et al

in Biomacromolecules (2007), 8(8), 2379-2387

Cataract surgery is a routine ophthalmologic intervention resulting in replacement of the opacified natural lens by a polymeric intraocular lens (IOL). A main postoperative complication, as a result of ... [more ▼]

Cataract surgery is a routine ophthalmologic intervention resulting in replacement of the opacified natural lens by a polymeric intraocular lens (IOL). A main postoperative complication, as a result of protein adsorption and lens epithelial cell (LEC) adhesion, growth, and proliferation, is the secondary cataract, referred to as posterior capsular opacification (PCO). To avoid PCO formation, a poly(ethylene glycol) (PEG) chemical coating was created on the surface of hydrogel IOLs. Attenuated total reflectance Fourier transform infrared spectroscopy, “captive bubble” and “water droplet” contact angle measurements, and atomic force microscopy analyses proved the covalent grafting of the PEG chains on the IOL surface while keeping unchanged the optical properties of the initial material. A strong decrease of protein adsorption and cell adhesion depending on the molar mass of the grafted PEG (1100, 2000, and 5000 g/mol) was observed by performing the relevant in vitro tests with green fluorescent protein and LECs, respectively. Thus, the study provides a facile method for developing materials with nonfouling properties, particularly IOLs. [less ▲]

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See detailImproved phase segmentation using RGB imaging
Tarquini, Simone; Pirard, Eric ULg

(1996)

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See detailImproved photo-induced cobalt-mediated radical polymerization in continuous flow photoreactors
Kermagoret, Anthony; Wenn, Benjamin; Debuigne, Antoine ULg et al

in Polymer Chemistry (2015), 6

The implementation of cobalt-mediated radical polymerization (CMRP) for continuous microreactor synthesis is described. We demonstrate how the utilization of flow photoreactors allows the speed up of the ... [more ▼]

The implementation of cobalt-mediated radical polymerization (CMRP) for continuous microreactor synthesis is described. We demonstrate how the utilization of flow photoreactors allows the speed up of the polymerization of vinyl acetate (VAc) under UV irradiation without loss of polymerization control. Microfluidics under UV irradiation has also been successfully implemented for the copolymerization of VAc with a less reactive olefin 1-octene (1-Oct). Reactivity ratios were deduced for this copolymerization system, and poly(VAc-co-1-Oct) copolymers containing up to 50 mol% of 1-Oct were synthesized. To the best of our knowledge, this is the first report on a photopolymerization where continuous flow techniques not only led to an improvement of reaction rates and dispersity, but also led to the avoidance of significant side-products that were observed in batch processing [less ▲]

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See detailImproved Policy Support Through Segmentation Based on Social Acceptance
Cools, Mario ULg; Brijs, Kris; Tormans, Hans et al

in Proceedings of the 90th Annual Meeting of the Transportation Research Board (DVD-ROM) (2011)

This paper proposes Q-methodology as a technique for the identification of more homogeneous subgroups or ‘segments’ within a rather heterogeneous overall population when it comes to social acceptance of ... [more ▼]

This paper proposes Q-methodology as a technique for the identification of more homogeneous subgroups or ‘segments’ within a rather heterogeneous overall population when it comes to social acceptance of demand restricting policy measures. Identification of such segments would allow policy makers to better tailor their future actions and thereby increase the chance for a successful implementation of the measures they propose. A set of 33 persons, selected in function of age, gender and car ownership evaluated the acceptability of a total number of 42 demand restricting policy measures. Special care was taken that the final set of statements covered the four classically distinguished demand restricting strategies, i.e., improved transport options, incentives for the use of alternative transport modes, parking and land-use management, and institutional policy revision. In addition, a balance between both ‘hard’ and ‘soft’ and ‘push’ and ‘pull’ measures was strived for. The results indicate that four different segments in terms of social acceptance of demand restricting policy measures, can be distinguished, i.e., travelers in favor of traffic calming, travelers against hard push measures, travelers in favor of demand restriction, and travelers against policy innovations. Besides the differences and similarities between these segments, the practical implications for policy makers are discussed, together with a series of specific recommendations and suggestions for future research. [less ▲]

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See detailImproved precision on the radius of the nearby super-Earth 55 Cnc e
Gillon, Michaël ULg; Demory, B.-O.; Benneke, B. et al

in Astronomy and Astrophysics (2012), 539

We report on new transit photometry for the super-Earth 55 Cnc e obtained with Warm Spitzer/IRAC at 4.5 microns. An individual analysis of these new data leads to a planet radius of 2.21-0.16+0.15 Rearth ... [more ▼]

We report on new transit photometry for the super-Earth 55 Cnc e obtained with Warm Spitzer/IRAC at 4.5 microns. An individual analysis of these new data leads to a planet radius of 2.21-0.16+0.15 Rearth, in good agreement with the values previously derived from the MOST and Spitzer transit discovery data. A global analysis of both Spitzer transit time-series improves the precision on the radius of the planet at 4.5 microns to 2.20+-0.12 Rearth. We also performed an independent analysis of the MOST data, paying particular attention to the influence of the systematic effects of instrumental origin on the derived parameters and errors by including them in a global model instead of performing a preliminary detrending-filtering processing. We deduce from this reanalysis of MOST data an optical planet radius of 2.04+-0.15 Rearth that is consistent with our Spitzer infrared radius. Assuming the achromaticity of the transit depth, we performed a global analysis combining Spitzer and MOST data that results in a planet radius of 2.17+-0.10 Rearth (13,820+-620 km). These results confirm that the most probable composition of 55 Cnc e is an envelope of supercritical water above a rocky nucleus. [less ▲]

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See detailAn improved preparation method of benzyl and thenyl triphenylphosphonium salt
Zhang, Jian-Xin; Dubois, Philippe ULg; Jérôme, Robert ULg

in Synthetic Communications (1996), 26(16), 3091-3095

New benzyl and thenyl phosphonium salts have been prepared by an improved method in solution from the parent alcohols and triphenylphosphine hydrobromide. Benzyl-type alcohols containing a tertiary amine ... [more ▼]

New benzyl and thenyl phosphonium salts have been prepared by an improved method in solution from the parent alcohols and triphenylphosphine hydrobromide. Benzyl-type alcohols containing a tertiary amine can also be converted within high yields to phosphonium salts by removing the formed water by azeotropic distillation. Solvent (methylene chloride, chloroform and acetonitrile) and temperature have been chosen in close relation to the alcohol reactivity. Purification is straightforward and yields are relatively high. [less ▲]

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See detailImproved PRESS sequence for lactate detection in the human vitreous body
Balteau, Evelyne ULg; COLLIGNON, Nathalie ULg; Robe, Pierre ULg et al

in Proceedings of the International Society for Magnetic Resonance in Medicine (2006), 14

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See detailImproved pressure contour analysis for estimating cardiac stroke volume using pulse wave velocity measurement.
Kamoi, Shun; Pretty, Christopher; Balmer, Joel et al

in BioMedical Engineering OnLine (2017), 16(1), 51

BACKGROUND: Pressure contour analysis is commonly used to estimate cardiac performance for patients suffering from cardiovascular dysfunction in the intensive care unit. However, the existing techniques ... [more ▼]

BACKGROUND: Pressure contour analysis is commonly used to estimate cardiac performance for patients suffering from cardiovascular dysfunction in the intensive care unit. However, the existing techniques for continuous estimation of stroke volume (SV) from pressure measurement can be unreliable during hemodynamic instability, which is inevitable for patients requiring significant treatment. For this reason, pressure contour methods must be improved to capture changes in vascular properties and thus provide accurate conversion from pressure to flow. METHODS: This paper presents a novel pressure contour method utilizing pulse wave velocity (PWV) measurement to capture vascular properties. A three-element Windkessel model combined with the reservoir-wave concept are used to decompose the pressure contour into components related to storage and flow. The model parameters are identified beat-to-beat from the water-hammer equation using measured PWV, wave component of the pressure, and an estimate of subject-specific aortic dimension. SV is then calculated by converting pressure to flow using identified model parameters. The accuracy of this novel method is investigated using data from porcine experiments (N = 4 Pietrain pigs, 20-24.5 kg), where hemodynamic properties were significantly altered using dobutamine, fluid administration, and mechanical ventilation. In the experiment, left ventricular volume was measured using admittance catheter, and aortic pressure waveforms were measured at two locations, the aortic arch and abdominal aorta. RESULTS: Bland-Altman analysis comparing gold-standard SV measured by the admittance catheter and estimated SV from the novel method showed average limits of agreement of +/-26% across significant hemodynamic alterations. This result shows the method is capable of estimating clinically acceptable absolute SV values according to Critchely and Critchely. CONCLUSION: The novel pressure contour method presented can accurately estimate and track SV even when hemodynamic properties are significantly altered. Integrating PWV measurements into pressure contour analysis improves identification of beat-to-beat changes in Windkessel model parameters, and thus, provides accurate estimate of blood flow from measured pressure contour. The method has great potential for overcoming weaknesses associated with current pressure contour methods for estimating SV. [less ▲]

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