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See detailAn effective decision procedure for linear arithmetic over the integers and reals
Boigelot, Bernard ULg; Jodogne, Sébastien ULg; Wolper, Pierre ULg

in ACM transactions on Computational Logic (2005), 6(3), 614--633

This article considers finite-automata-based algorithms for handling linear arithmetic with both real and integer variables. Previous work has shown that this theory can be dealt with by using finite ... [more ▼]

This article considers finite-automata-based algorithms for handling linear arithmetic with both real and integer variables. Previous work has shown that this theory can be dealt with by using finite automata on infinite words, but this involves some difficult and delicate to implement algorithms. The contribution of this article is to show, using topological arguments, that only a restricted class of automata on infinite words are necessary for handling real and integer linear arithmetic. This allows the use of substantially simpler algorithms, which have been successfully implemented. [less ▲]

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See detailAn effective finite-element-based method for the computation of nonlinear normal modes of nonconservative systems
Renson, Ludovic ULg; Deliège, Geoffrey ULg; Kerschen, Gaëtan ULg

in Meccanica (2014), 49(8), 1901-1916

This paper addresses the numerical computation of nonlinear normal modes defined as two-dimensional invariant manifolds in phase space. A novel finite-element-based algorithm, combining the streamline ... [more ▼]

This paper addresses the numerical computation of nonlinear normal modes defined as two-dimensional invariant manifolds in phase space. A novel finite-element-based algorithm, combining the streamline upwind Petrov-Galerkin method with mesh moving and domain prediction-correction techniques, is proposed to solve the manifold-governing partial differential equations. It is first validated using conservative examples through the comparison with a reference solution given by numerical continuation. The algorithm is then demonstrated on nonconservative examples. [less ▲]

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See detailEffective heat conduction in dispersion of wires
Behrang, Arash; grmela, miroslav; Dubois, Charles et al

in Applied Physics Letters (2014), 104

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See detailEffective Iterative Solvers for Highly Non-Linear & Large Deformation Pressure Dependent Problems
Boman, Romain ULg; Colantonio, Laurent; Ponthot, Jean-Philippe ULg

in Van Keer, R.; Verhegghe, B.; Hogge, M. (Eds.) et al Proceedings of ACOMEN'98, Advanced Computational Methods in Engineering, part 2: Contributed papers (1998, September)

In this paper, we present a stress update scheme for non-deviatoric elastoviscoplastic models, which can be considered as an extension of the radial return method for classical plasticity. We use the ... [more ▼]

In this paper, we present a stress update scheme for non-deviatoric elastoviscoplastic models, which can be considered as an extension of the radial return method for classical plasticity. We use the unconditionally stable backward Euler scheme to obtain the viscoplastic solution at each increment. To solve the large sparse non symmetric iteration matrix, we use the GMRES method. This fast iterative solver, in conjunction with an appropriate preconditioner, can save a lot a memory and CPU time when 3D problem are considered. A comparison between direct and iterative solvers will be discussed on two applications of cold compaction of powders. [less ▲]

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See detailEffective masses in relativistic approaches to the nucleon-nucleus mean field
Jaminon, Martine ULg; Mahaux, Claude ULg

in Physical Review. C : Nuclear Physics (1989), 40

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See detailEffective particles and classification of periodic orbits of homogeneous granular chains with no precompression
Starosvetsky, Y.; Jayaprakash, K.R.; Vakakis, A.F. et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 85

We develop a systematic methodology for classifying the periodic orbits of homogeneous ordered granular chains with no dissipation, under the assumption that all granules oscillate with the same frequency ... [more ▼]

We develop a systematic methodology for classifying the periodic orbits of homogeneous ordered granular chains with no dissipation, under the assumption that all granules oscillate with the same frequency. The analysis is based on the idea of balancing linear momentum for sets of auxiliary models consisting of “effective particles.” The auxiliary models may be defined for any given finite, ordered granular chain composed of n identical granules (beads) that interact with each other through strongly nonlinear Hertzian interaction law. In turn, the auxiliary models may be effectively used for theoretically predicting the total number of periodic orbits and the corresponding amplitude ratios of the granules. Good correspondence between the theoretical models and results of direct numerical simulations is reported. The results presented herein can be used to understand the complex intrinsic dynamics of ordered granular media, and to systematically study the generation of mode localization in these strongly nonlinear systems. The derived analytical models can be utilized to predict the response of the effective particles, and based on that, to predict primary pulse transmission in periodic layered media with granular interfaces. Moreover, our analysis can be extended to the general class of nonlinear chains of particles with smooth interacting potentials and possible separation between particles during the motion. [less ▲]

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See detailEffective porosity values used in calibrated transport simulations in a fissured and slightly karstified chalk aquifer
Hallet, Vincent; Dassargues, Alain ULg

in Herbert, M.; Kovar, K. (Eds.) Groundwater Quality 1998, Tübinger Geowissenschaftliche Arbeiten (TGA) (1998)

In fissured and slighly karstified chalks, the main difficulty for modelling groundwater flow and transport consists in finding a good approximation of the highly heterogeneous reality by a REV concept ... [more ▼]

In fissured and slighly karstified chalks, the main difficulty for modelling groundwater flow and transport consists in finding a good approximation of the highly heterogeneous reality by a REV concept. No major problem is encountered for groundwater flow simulations when the high contrast in hydraulic conductivity can be given to the cells/elements of the model. The Darcy’s law is applied in terms of specific flow rate, through the REV. When considering transport, it is often assumed that the calibrated field of hydraulic conductivity should be kept unchanged. Consequently, ‘physically non acceptable’ values of the effective porosity are often needed to obtain a match between modelled and measured breakthrough curves. The model becomes, to some extent, a black-box model. [less ▲]

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See detailEffective Production of the Biodiesel Additive STBE by a Continuous Flow Process
Monbaliu, Jean-Christophe ULg; Winter, Marc; Chevalier, Bérengère et al

in Bioresource Technology (2011), 102

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See detailEffective resolution of racemic pirlindole at the preparative scale
De Tullio, Pascal ULg; Ceccato, A.; Liégeois, Jean-François ULg et al

in Chirality (1999), 11

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See detailEffective segmentation of green vegetation for resource-constrained real-time applications
Krishna Moorthy Parvathi, Sruthi Moorthy ULg; Boigelot, Bernard ULg; Mercatoris, Benoît ULg

Scientific conference (2015, July 15)

This paper describes an improved algorithm for segmentation of green vegetation under uncontrolled illumination conditions and also suitable for resource-constrained real-time applications. The proposed ... [more ▼]

This paper describes an improved algorithm for segmentation of green vegetation under uncontrolled illumination conditions and also suitable for resource-constrained real-time applications. The proposed algorithm uses a naïve Bayesian model to effectively combine various manually extracted features from two different color spaces namely RGB and HSV. The evaluation of 100 images indicated the better performance of the proposed algorithm than the vegetation index-based methods with comparable execution time. Moreover, the proposed algorithm performed better than the state-of-the-art EASA-based algorithms in terms of processing time and memory usage. [less ▲]

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See detailEffective soil hydraulic conductivity predicted with the maximum power principle
Westhoff, Martijn ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

Conference (2016, April)

Drainage of water in soils happens for a large extent through preferential flowpaths, but these subsurface flowpaths are extremely difficult to observe or parameterize in hydrological models. To ... [more ▼]

Drainage of water in soils happens for a large extent through preferential flowpaths, but these subsurface flowpaths are extremely difficult to observe or parameterize in hydrological models. To potentially overcome this problem, thermodynamic optimality principles have been suggested to predict effective parametrization of these (sub-grid) structures, such as the maximum entropy production principle or the equivalent maximum power principle. These principles have been successfully applied to predict heat transfer from the Equator to the Poles, or turbulent heat fluxes between the surface and the atmosphere. In these examples, the effective flux adapts itself to its boundary condition by adapting its effective conductance through the creation of e.g. convection cells. However, flow through porous media, such as soils, can only quickly adapt its effective flow conductance by creation of preferential flowpaths, but it is unknown if this is guided by the aim to create maximum power. Here we show experimentally that this is indeed the case: In the lab, we created a hydrological analogue to the atmospheric model dealing with heat transport between Equator and poles. The experimental setup consists of two freely draining reservoirs connected with each other by a confined aquifer. By adding water to only one reservoir, a potential difference will build up until a steady state is reached. From the steady state potential difference and the observed flow through the aquifer, and effective hydraulic conductance can be determined. This observed conductance does correspond to the one maximizing power of the flux through the confined aquifer. Although this experiment is done in an idealized setting, it opens doors for better parameterizing hydrological models. Furthermore, it shows that hydraulic properties of soils are not static, but they change with changing boundary conditions. A potential limitation to the principle is that it only applies to steady state conditions. Therefore the rate of adaptation of hydraulic properties should be faster than the rate of change in boundary conditions. [less ▲]

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See detailEffective spin model for interband transport in a Wannier-Stark lattice system
Plötz, Patrick; Schlagheck, Peter ULg; Wimberger, Sandro

in European Physical Journal D -- Atoms, Molecules, Clusters & Optical Physics (2011), 63

We show that the interband dynamics in a tilted two-band Bose-Hubbard model can be reduced to an analytically accessible spin model in the case of resonant interband oscillations. This allows us to ... [more ▼]

We show that the interband dynamics in a tilted two-band Bose-Hubbard model can be reduced to an analytically accessible spin model in the case of resonant interband oscillations. This allows us to predict the revival time of these oscillations which decay and revive due to inter-particle interactions. The presented mapping onto the spin model and the so achieved reduction of complexity has interesting perspectives for future studies of many-body systems. [less ▲]

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See detailEffective stress method to be used in beam finite elements to take local instabilities into account
Franssen, Jean-Marc ULg; Cowez, Baptiste; Gernay, Thomas ULg

in Fire Safety Science 11 (2014, February)

In the fire situation, Bernoulli beam finite elements are the workhorse used in numerical calculation model for simulating the behaviour of the structure. Such finite elements treat all sections as class ... [more ▼]

In the fire situation, Bernoulli beam finite elements are the workhorse used in numerical calculation model for simulating the behaviour of the structure. Such finite elements treat all sections as class 1 (stocky) sections whatever the slenderness of the plates that make the section, allowing the development of a full plastic stress distribution in the section which leads to complete plastic redistribution along the members in the structure. This type of element is thus not adapted for modeling structures that contain slender sections of class 2, 3 or 4. This document presents a new approach to take into account local instabilities in slender sections using beam finite elements. The new approach is based on an effective constitutive law of steel. The effective law is not symmetrical with respect to tension and compression because, in tension, the stress-strain relationship is not modified whereas, in compression, the stress-strain relationship is modified. [less ▲]

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See detailEffective temperature of ions in traveling wave ion mobility spectrometry
Morsa, Denis ULg; Gabelica, Valérie ULg; De Pauw, Edwin ULg

in Analytical Chemistry (2011), 83(14), 5775-5782

Traveling wave ion mobility spectrometers (TW IMS) operate at significantly higher fields than drift tube ion mobility spectrometers. Here we measured the fragmentation of the fragile p ... [more ▼]

Traveling wave ion mobility spectrometers (TW IMS) operate at significantly higher fields than drift tube ion mobility spectrometers. Here we measured the fragmentation of the fragile p-methoxybenzylpyridinium ion inside the TW ion mobility cell of the first-generation SYNAPT HDMS spectrometer. The ion’s vibrational internal energy was quantified by a vibrational effective temperature Teff,vib, which is the mean temperature of the ions inside the cell that would result in the same fragmentation yield as observed experimentally. Significant fragmentation of the probe ion inside the TW IMS cell was detected, indicating that field heating of the ions takes place in TW IMS. For typical small molecule IMS conditions, Teff,vib = 555 ± 2 K. The variations of the effective temperature were studied as a function of the IMS parameters, and we found that Teff,vib decreases when the wave height decreases, when the pressure increases, or when the wave speed increases. The energy transfer efficiency of argon is higher than for He, N2 or CO2. Teff,vib being directly related to the ion speed inside the TW IMS, our results also provide new insight on the ion movement in TW IMS. We also discuss the influence of field heating of ions for calibration and structural studies in TW IMS. [less ▲]

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See detailEffective treatment of Jo-1-associated polymyositis with T-cell-depleted autologous peripheral blood stem cell transplantation.
Baron, Frédéric ULg; Ribbens, Clio ULg; Kaye, O. et al

in British Journal of Haematology (2000), 110(2), 339-342

A patient with Jo-1 antibody-associated polymyositis (Jo-1 PM) had a Karnofsky score of 40% and severe muscle, liver and lung damage that was refractory to standard therapy. The female patient received an ... [more ▼]

A patient with Jo-1 antibody-associated polymyositis (Jo-1 PM) had a Karnofsky score of 40% and severe muscle, liver and lung damage that was refractory to standard therapy. The female patient received an autologous T-cell-depleted haematopoietic stem cell transplant (HSCT) after myeloablative conditioning. The transplant procedure was complicated by severe adult respiratory distress syndrome (ARDS) and adenovirus-associated haemorrhagic cystitis as well as cytomegalovirus (CMV) reactivation. The patient's creatinine phosphokinase (CPK) and alanine transaminase (ALT) values were normal on day 21. The patient's strength has improved remarkably and her dyspnoea is subjectively improved. At 15 months after the transplant, the patient was well with a Karnofsky score of 80% and had been off any therapy, including steroids, for 14 months. [less ▲]

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See detaileffective use of dolomitic material in Mbuji-Mayi region
Matamba Jibikila, Raphaël ULg

Conference (2012, September 12)

En vue d'une utilisation efficace de matériaux dolomitiques du supergroupe de Mbuji-Mayi (RD Congo), une caractérisation méticuleuse de chaque faciès de matériau s'impose. Cela permettrait une bonne ... [more ▼]

En vue d'une utilisation efficace de matériaux dolomitiques du supergroupe de Mbuji-Mayi (RD Congo), une caractérisation méticuleuse de chaque faciès de matériau s'impose. Cela permettrait une bonne gestion de ressources en définissant pour chaque faciès, des applications optimales et durables. [less ▲]

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