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See detailAn efficient DNA isolation protocol for filamentous cyanobacteria of the genus Arthrospira
Morin, Nicolas ULg; Vallaeys, Tatiana; Hendrickx, Larissa et al

in Journal of Microbiological Methods (2010), 80

Thanks to their photosynthetic and nutritive properties, cyanobacteria of the Arthrospira genus are of interest as food supplements, as efficient oxygen producing life support system organisms for manned ... [more ▼]

Thanks to their photosynthetic and nutritive properties, cyanobacteria of the Arthrospira genus are of interest as food supplements, as efficient oxygen producing life support system organisms for manned space flight, and for the production of biofuels. Despite these potential valuable applications, full genome sequences and genetic information in general on Arthrospira remain scarce. This is mainly due to the difficulty to extract sufficient high molecular weight nucleic acids from these filamentous cyanobacteria. In this article, an efficient and reproducible DNA extraction procedure for cyanobacteria of the genus Arthrospira was developed. The method is based on the combination of a soft mechanical lysis with enzymatic disruption of the cell wall. The comparison with other extraction protocols clearly indicates that this optimised method allows the recovery of a larger amount of DNA. Furthermore, the extracted DNA presents a high molecular weight, a reduced degradation and an excellent overall quality. It can be directly used for molecular biology purposes such as PCR, and clone library construction. [less ▲]

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See detailAn Efficient Dual and Triple Frequency Preprocessing Method for GALILEO and GPS Signals
Lonchay, Matthieu ULg; Bidaine, Benoît ULg; Warnant, René ULg

in 3rd International Colloquium – Scientific and Fundamentals Aspects of the GALILEO Programme (2011, September 02)

Data preprocessing is a mandatory stage for most of GNSS applications. In the frame of space weather and precise point positioning applications, the Geomatics Unit of the University of Liège has purchased ... [more ▼]

Data preprocessing is a mandatory stage for most of GNSS applications. In the frame of space weather and precise point positioning applications, the Geomatics Unit of the University of Liège has purchased two Septentrio PolaRx3eG receivers which allow tracking GPS L1/L5 and Galileo E1/E5a signals. In order to fully exploit these new data, we developed a preprocessing method extending existing techniques. Our preprocessing method consists of three consecutive steps. The first step is devoted to the compensation of receiver clock slips affecting code pseudorange and carrier-phase measurements. The second step covers cycle slips detection and the third step assesses data quality in terms of noise essentially affecting code pseudorange measurements. This preprocessing method was initially developed for GPS L1/L5 and Galileo E1/E5a dual frequency data but finally enhanced to also preprocess triple frequency data from first operational Galileo satellites as soon as data are available. The developed method already showed promising results. [less ▲]

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See detailAn efficient dynamic state estimator for large-scale electric power systems
Rousseaux, Patricia ULg

in Proceedings of the IFAC Symposium on Power Systems. Modelling and Control applications (1988)

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See detailEfficient estimation of the high-order response statistics of a wind-excited oscillator with nonlinear velocity feedback
Denoël, Vincent ULg; Carassale, Luigi

in Proceedings of the XIII Conference of the Italian Association for Wind engineering (2014)

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See detailEfficient Evaluation of the Geometrical Validity of Curvilinear Finite Elements
Johnen, Amaury ULg; Remacle, Jean-François; Geuzaine, Christophe ULg

in Proceedings of the 5th international conference on Advanced COmputational Methods in ENgineering (ACOMEN 2011) (2011, November 14)

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See detailEfficient finite element assembly of high order whitney forms
Marsic, Nicolas ULg; Geuzaine, Christophe ULg

in IET Conference Proceedings (2014)

This paper presents an efficient method for the finite element assembly of high order Whitney elements. We start by reviewing the classical assembly technique and by highlighting the most time consuming ... [more ▼]

This paper presents an efficient method for the finite element assembly of high order Whitney elements. We start by reviewing the classical assembly technique and by highlighting the most time consuming part. Then, we show how this classical approach can be reformulated into a computationally efficient matrix - matrix product. We also address the problem of the basis orientation by considering more than one reference space. We conclude by presenting numerical results on a wave guide problem. [less ▲]

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See detailAn efficient flamelet-based combustion model for compressible flows
Saghafian, Amirreza; Terrapon, Vincent ULg; Pitsch, Heinz

in Combustion and Flame (2014)

A combustion model based on a flamelet/progress variable approach for high-speed flows is introduced. In the proposed formulation, the temperature is computed from the transported total energy and ... [more ▼]

A combustion model based on a flamelet/progress variable approach for high-speed flows is introduced. In the proposed formulation, the temperature is computed from the transported total energy and tabulated species mass fractions. Only three additional scalar equations need to be solved for the combustion model. Additionally, a flamelet library is used that is computed in a pre-processing step. This approach is very efficient and allows for the use of complex chemical mechanisms. An approximation is also introduced to eliminate costly iterative steps during the temperature calculation. To better account for compressibility effects, the chemical source term of the progress variable is rescaled with the density and temperature. The compressibility corrections are analyzed in an a priori study. The model is also tested in both Reynolds-averaged Navier–Stokes (RANS) and large-eddy simulation (LES) computations of a hydrogen jet in a supersonic transverse flow. Comparison with experimental measurements shows good agreement, particularly for the LES case. It is found that the disagreement between RANS results and experimental data is mostly due to the mixing model deficiencies and the presumed probability density functions used in the RANS formulation. A sensitivity study of the proposed model shows the importance of the compressibility corrections especially for the source term of the progress variable. [less ▲]

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See detailAn Efficient Flamelet-based Combustion Model for Supersonic Flows
Saghafian, Amirreza; Terrapon, Vincent ULg; Ham, Frank et al

in 17th AIAA International Space Planes and Hypersonic Systems and Technologies Conference 2011, Vol. 2; No AIAA 2011-2267 (2011, April)

A combustion model based on a Flamelet/Progress Variable approach for high-speed flows is introduced. In the proposed formulation, the temperature is computed from the transported total energy and ... [more ▼]

A combustion model based on a Flamelet/Progress Variable approach for high-speed flows is introduced. In the proposed formulation, the temperature is computed from the transported total energy and tabulated species mass fractions. The combustion is thus modeled by 3 additional scalar equations and a chemistry table that is computed in a pre-processing step. This approach is very efficient and allows the use of complex chemical mechanisms. An approximation is also introduced to eliminate costly iteration steps during the temperature calculation. To better account for compressibility e ects, the source term for the progress variable is rescaled with the pressure. The model is tested in both RANS and LES computations of a hydrogen jet in a supersonic transverse flow. Comparison with experimental measurements shows good agreement, particularly in the LES case. It is also found that the disagreement between RANS results and experimental data is mostly due to the mixing model de ciencies used in RANS. [less ▲]

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See detailAn efficient formulation for the simulation of elastic wave propagation in 1-dimensional collinding bodies
Depouhon, Alexandre ULg; Detournay, Emmanuel; Denoël, Vincent ULg

in Proceedings of the 11th International Conference on Vibration Problems (2013, September 09)

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See detailAn efficient global methodology for hazard analysis of dams complexes and cascades
Dewals, Benjamin ULg; Archambeau, Pierre ULg; Erpicum, Sébastien ULg et al

in Brebbia, C. A.; Popov, V.; Beriatos, E. (Eds.) Risk analysis Vol. 6 (2008)

Hazard analysis of dams arranged in complex or in cascade may involve the assessment of a large number of different scenarios of combined failures. However, a tremendous computation time would be needed ... [more ▼]

Hazard analysis of dams arranged in complex or in cascade may involve the assessment of a large number of different scenarios of combined failures. However, a tremendous computation time would be needed to perform a detailed modelling of the flows generated by all possible scenarios. Therefore, the present paper describes a methodology for analysing the flows induced by the most relevant incidents occurring on a complex or in a cascade of dams and reservoirs. The methodology combines several hydrodynamic models, including the two-dimensional flow solver WOLF 2D and a simplified lumped hydrodynamic model, to simulate the flows induced on the dams complex, the potential breaching in cascade of other dams, as well as the propagation of the flood wave in the whole downstream valley. The application of the methodology to a practical case study involving a complex of five dams is also described. [less ▲]

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See detailEfficient hydraulic numerical modeling with multiblock grids and linked models
Erpicum, Sébastien ULg; Archambeau, Pierre ULg; Dewals, Benjamin ULg et al

in Houille Blanche (2011), 3

In the field of numerical hydraulic engineering, the size of the simulations is one of the current challenges to consider with sufficient precision the large areas involved by practical applications. In ... [more ▼]

In the field of numerical hydraulic engineering, the size of the simulations is one of the current challenges to consider with sufficient precision the large areas involved by practical applications. In this scope, the linking in the same computational domain of different solvers, each one used in the part of the simulation where its characteristics are most suitable, opens the door to huge modeling possibilities. Such optimized hydraulic numerical modeling is presented in this paper with a multiblock multimodel 2D solver and its linking to a 1D model. After a description of the solvers, with emphasis on the linking procedures, theoretical test cases and real applications are presented. [less ▲]

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See detailEfficient Immunoselection of Cytolytic Effectors with a Magnetic Cell Sorter
Jacobs, Nathalie ULg; Moutschen, Michel P; Boniver, Jacques ULg et al

in Research in Immunology (1993), 144(2), 141-50

This paper describes a rapid and efficient method for the sorting of in vitro activated cytolytic effectors cells. For cytotoxic assays, a large number of cells with conserved function must be rapidly ... [more ▼]

This paper describes a rapid and efficient method for the sorting of in vitro activated cytolytic effectors cells. For cytotoxic assays, a large number of cells with conserved function must be rapidly obtained. Immunomagnetic sorting was chosen because it is faster than flow cytometry sorting. The MACS system requires the use of paramagnetic beads of small diameter (100-150 nm), reputed to interfere minimally with cell function. In order to generate the cytolytic effectors, peripheral blood lymphocytes were cultivated in the presence of interleukin-2 (50 U/ml) and anti-CD3 monoclonal antibody (BMA030, 100 ng/ml) for 4 days. Cell separation was based on the membrane expression of the CD3 complex. The purity obtained for positive (CD3+) cell sorting with the MACS was higher than 95%. The purity of negative (CD3-) cell fraction was more variable, but further purification by flow cytometry rapidly yielded purity higher than 95%. Cytotoxic assays were performed against four target cell lines (K562, Daudi, HL60 and U937) and proliferation assays showed that both negatively and positively selected populations had conserved their function acquired during culture in the presence of anti-CD3 mAb and IL2. [less ▲]

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See detailAn efficient implicit approach for the thermomechanical behavior of materials submitted to high strain rates
Jeunechamps, Pierre-Paul ULg; Ponthot, Jean-Philippe ULg

in Journal de Physique IV (2006), 134

In the present paper, three solutions are proposed to simulate fast phenomena with finite element method at best. At first, material constitutive laws of Johnson-Cook and Zerilli-Armstrong types are ... [more ▼]

In the present paper, three solutions are proposed to simulate fast phenomena with finite element method at best. At first, material constitutive laws of Johnson-Cook and Zerilli-Armstrong types are implemented. These well-known laws are efficient for the description of material behavior at high velocities, especially for material used in automotive or aeronautics industry. The second contribution of this paper is the coupling of an implicit Chung-Hulbert algorithm taking into account the inertial effects with a staggered scheme for solving the thermal problem. The last input of this paper is the use of EAS (Enhanced Assumed Strain) finite elements to better capture complex strain modes, especially bending that is not accurately evaluated with classical finite elements. These EAS finite elements are used in the scope of thermomechanical dynamic phenomena implemented in a modular C++ environment at the University of Liege in the home made software METAFOR. [less ▲]

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See detailAn Efficient Implicit Scheme for the Treatment of Contact between Deformable Bodies
GRAILLET, D.; Ponthot, Jean-Philippe ULg

in . Proceedings of "NUMIFORM'98, Simulation of Materials Processing: Theory, Methods and Applications (1998, June)

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See detailAn Efficient Implicit Scheme for the Treatment of Contact Between Deformable Bodies
Ponthot, Jean-Philippe ULg; GRAILLET

in Idelsohn, S.; Onate; Dvorkin (Eds.) Proceedings of "World Congress on Computational Mechanics IV (1998)

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See detailAn Efficient Implicit Scheme for the Treatment of Frictional Contact between Deformable Bodies
GRAILLET, D.; Ponthot, Jean-Philippe ULg

in Proceedings of "First ESAFORM Conference on Material Forming" (1998)

Detailed reference viewed: 5 (3 ULg)
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See detailEfficient Implicit Schemes for Finite Element Impact Simulation
Ponthot, Jean-Philippe ULg; Graillet, D.

in International Journal of Crashworthiness (1999), 4(3), 273-285

Detailed reference viewed: 10 (4 ULg)
See detailEfficient Implicit Schemes for High-Speed Dynamics and Crash Simulation. Application to shock-absorber devices
Hogge, Michel ULg; GRAILLET, D.; Ponthot, Jean-Philippe ULg

in Proceedings of «ACOMEN’98», Advanced Computational Methods in Engineering: Invited Papers (1998, September)

Detailed reference viewed: 23 (1 ULg)
See detailEfficient implicit schemes for the treatment of the contact between deformable bodies. Application to shock absorber devices
GRAILLET, D.; Stainier, Laurent ULg; Ponthot, Jean-Philippe ULg

in Proceedings of the Fifth National Belgian Congress on Theoretical and Applied Mechanics (2000)

Detailed reference viewed: 17 (8 ULg)