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Peer Reviewed
See detailDynamic state prediction and hierarchical filtering for power system estimation
Rousseaux, Patricia ULg; Van Cutsem, Thierry ULg; Mallieu, Didier et al

in Automatica (1988), 25(5), 595-618

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See detailA Dynamic Stiffness-Transfer Matrix Method for Forced Response Analysis of One-Dimensional Structures
Chen, S. L.; Golinval, Jean-Claude ULg; Géradin, Michel ULg

in Journal of Modal Analysis (1994), (Avril),

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See detailDynamic Stress and Fatigue Life Prediction Using Modal Testing and Model Correlation
Simon, Daniel; Golinval, Jean-Claude ULg

Conference given outside the academic context (1996)

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See detaildynamic structure of the radial glial fiber system of the developing murine cerebral wall.an immunocytochemical analysis
Gadisseux, Jean-François; Evrard, Philippe; Misson, Jean-Paul ULg et al

in Developmental Brain Research (1989), 50

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See detailDynamic Style Analysis with Errors in Variables
Bodson, Laurent ULg

Master of advanced studies dissertation (2007)

This paper revisits the traditional return-based style analysis (RBSA) in presence of time-varying exposures and errors in variables. We apply a selection algorithm using the Kalman filter to identify the ... [more ▼]

This paper revisits the traditional return-based style analysis (RBSA) in presence of time-varying exposures and errors in variables. We apply a selection algorithm using the Kalman filter to identify the more appropriate benchmarks and we compute their corresponding higher moment estimators (HME), i.e. the measurement error series introducing the (cross) moments of order three and four. Then, we retain the most significant HME and we add them to the selected benchmarks. Therefore, we obtain the most relevant benchmarks with none, some or all their HME as benchmarks explaining the analyzed fund return. We finally run the Kalman filter on the principal components of this set of selected benchmarks to avoid multicollinearity problems. Analysing EDHEC alternative indexes styles, we show that this technique improves the factor loadings and permits to identify more precisely the return sources of the considered fund. [less ▲]

Detailed reference viewed: 56 (6 ULg)
Peer Reviewed
See detailDynamic surface properties of the proteose-peptone fraction of bovine milk
Innocente, N.; Corradini, C.; Blecker, Christophe ULg et al

in Journal of Dairy Science (1998), 81(7), 1833-1839

Proteose-peptone is a heat-stable and acid-soluble protein fraction of milk that has important functional properties. Component 3, which is the most hydrophobic fraction, appears to be largely responsible ... [more ▼]

Proteose-peptone is a heat-stable and acid-soluble protein fraction of milk that has important functional properties. Component 3, which is the most hydrophobic fraction, appears to be largely responsible for the physicochemical properties of proteose-peptones and for their important biological role in milk. In this study, total proteose-peptone was prepared from bulk skim milk by precipitation with ammonium sulfate, and the hydrophobic fraction was purified by FPLC(R) (Pharmacia Fine Chemicals, Uppsala, Sweden). The drop volume method was used to investigate the dynamic surface activity of total proteose-peptone and component 3 of proteose-peptone at the air-water interface and at the oil-water interface. In general, proteose-peptones are good surfactants at both interfaces. Of all proteose-peptones, component 3 causes a more rapid reduction of interfacial tension in both interfaces. A system for measuring film balance was used to obtain more information about the surface and mechanical properties of proteose-peptone monolayers. We deduced from the compression isotherms that component 3 of proteose-peptone and total proteose-peptone films spread at the air-water interface present different mechanical properties. [less ▲]

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See detailDynamic T cell receptor clonotype changes in synovial tissue of patients with early rheumatoid arthritis: effects of treatment with cyclosporin A (Neoral)
VanderBorght, Ann; De Keyser, Filip; Geusens, Piet et al

in Journal of Rheumatology (2002), 29(3), 416-426

OBJECTIVE: To study T cell receptor (TCR) repertoire changes in synovial membrane over a 16 week period in patients with early rheumatoid arthritis (RA); and to study the influence of cyclosporin A (CSA ... [more ▼]

OBJECTIVE: To study T cell receptor (TCR) repertoire changes in synovial membrane over a 16 week period in patients with early rheumatoid arthritis (RA); and to study the influence of cyclosporin A (CSA) on TCR repertoire in a subgroup of these patients. METHODS: Synovial tissue biopsies and paired blood samples were obtained from 12 patients with early RA at 2 time points. Seven patients were treated with CSA (Neoral-Sandimmun, 3 mg/kg/day) and 5 patients with placebo for 16 weeks. TCR V gene repertoires were analyzed by semiquantitative PCR-ELISA. CDR3 spectratyping and sequence analysis was used to compare TCR clonotype distributions. RESULTS: TCR-specific mRNA was detected in all synovial tissue biopsies at the first sampling, but in only 8/12 biopsies 16 weeks later (4/7 CSA group, 4/5 placebo group). Overrepresented TCR BV genes were found in biopsies of 10/12 patients at the first time point, and in 7/12 patients after 16 weeks (3/7 CSA, 4/5 placebo). CDR3 sequence analysis revealed dynamic repertoire changes with only a few persisting clonotypes in the synovial tissue of placebo controls. Persisting T cell clonotypes were more frequently found in the synovial tissue of CSA treated patients compared to the placebo group. CONCLUSION: These data suggest a dynamic process of T cell recruitment in the joints of RA patients. This process, possibly due to activation and subsequent infiltration of new T cell clones, apparently is influenced by CSA treatment. Synovial tissue T cells were no longer detected after 16 weeks' CSA treatment in 3 patients. In the other CSA treated patients, new T cell clones infiltrated, while other clones were persistently represented in the joints. These data may have important consequences for the design of T cell targeted therapies for RA. [less ▲]

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See detailDynamic Thermal Modeling of a Radiant Panel System and its Environment for Commissioning: Application to a Case Study
Fonseca Diaz, Nestor; Bertagnolio, Stéphane ULg

in Proceedings of the 9th International Conference for Enhanced Building Operation, Austin, TX (2009, November)

As a part of a commissioning study, the cooling ceiling system of a large commercial building located in Belgium is evaluated. A representative office has been instrumented and data on the cooling ceiling ... [more ▼]

As a part of a commissioning study, the cooling ceiling system of a large commercial building located in Belgium is evaluated. A representative office has been instrumented and data on the cooling ceiling system operating in real conditions have been collected. The simulation of the whole system is performed by means of a dynamic thermal model of the building and its HVAC system. The model considers the radiant panels as a dynamic-state finned heat exchanger connected to a simplified lumped dynamic model of the building. The behavior of the radiant ceiling system and the interactions with his environment (walls, ventilated façade, internal loads and ventilation system) has been experimentally and numerically evaluated. Commissioning test results show that the influence of surfaces temperatures inside the room, especially the façade, is considerable. Then, it is clear that the radiant ceiling system must be evaluated together with its designed environment and not as separate HVAC equipment. [less ▲]

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See detailA dynamic upper atmosphere of Venus as revealed by VIRTIS on Venus Express
Drossart, P.; Piccioni, G.; Gérard, Jean-Claude ULg et al

in Nature (2007), 450

The upper atmosphere of a planet is a transition region in which energy is transferred between the deeper atmosphere and outer space. Molecular emissions from the upper atmosphere (90-120 km altitude) of ... [more ▼]

The upper atmosphere of a planet is a transition region in which energy is transferred between the deeper atmosphere and outer space. Molecular emissions from the upper atmosphere (90-120 km altitude) of Venus can be used to investigate the energetics and to trace the circulation of this hitherto little-studied region. Previous spacecraft(1) and ground-based(2-4) observations of infrared emission from CO2, O-2 and NO have established that photochemical and dynamic activity controls the structure of the upper atmosphere of Venus. These data, however, have left unresolved the precise altitude of the emission(1) owing to a lack of data and of an adequate observing geometry(5,6). Here we report measurements of day-side CO2 non-local thermodynamic equilibrium emission at 4.3 mu m, extending from 90 to 120 km altitude, and of night-side O-2 emission extending from 95 to 100 km. The CO2 emission peak occurs at similar to 115 km and varies with solar zenith angle over a range of similar to 10 km. This confirms previous modelling(7), and permits the beginning of a systematic study of the variability of the emission. The O-2 peak emission happens at 96 km +/- 1 km, which is consistent with three-body recombination of oxygen atoms transported from the day side by a global thermospheric sub-solar to anti-solar circulation, as previously predicted(8). [less ▲]

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See detailDynamical atomic charges: The case of ABO(3) compounds
Ghosez, Philippe ULg; Michenaud, J. P.; Gonze, X.

in Physical Review. B : Condensed Matter (1998), 58(10), 6224-6240

Based on recent first-principles computations in perovskite compounds, especially BaTiO3, we examine the significance of the Born effective charge concept and contrast it with other atomic charge ... [more ▼]

Based on recent first-principles computations in perovskite compounds, especially BaTiO3, we examine the significance of the Born effective charge concept and contrast it with other atomic charge definitions, either static (Mulliken, Bader, etc.) or dynamical (Callen, Szigeti, etc.). It is shown that static and dynamical charges are not driven by the same underlying parameters. A unified treatment of dynamical charges in periodic solids and large clusters is proposed. The origin of the difference between static and dynamical charges is discussed in terms of local polarizability and delocalized transfers of charge: local models succeed in reproducing anomalous effective charges thanks to large atomic polarizabilities but, in ABO(3) compounds, ab initio calculations favor the physical picture based upon transfer of charges. Various results concerning barium and strontium titanates are presented. The origin of anomalous Born effective charges is discussed thanks to a band-by-band decomposition which allows us to identify the displacement of the Wannier center of separated bands induced by an atomic displacement. The sensitivity of the Born effective charges to microscopic and macroscopic strains is examined. Finally, we estimate the spontaneous polarization in the four phases of barium titanate. [less ▲]

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See detailDynamical behaviour of electro-mechanical coupled problem
Rochus, Véronique ULg; rixen, Daniel; Golinval, Jean-Claude ULg

Conference (2004)

MEMS are very small devices in which electric as well as mechanical dynamics phenomena appear. Because of the microscopic scale, some strong coupling effects between the different physical fields appear ... [more ▼]

MEMS are very small devices in which electric as well as mechanical dynamics phenomena appear. Because of the microscopic scale, some strong coupling effects between the different physical fields appear, and some forces, which are negligible at macroscopic scales, have to be taken into account. In order to make a good design of these micro-systems, it is important to analyse the coupling between the electrical and mechanical fields. This paper concerns the modelling of the strong electromechanical coupling appearing in micro-electro-mechanical systems (MEMS). The finite element method (FEM) is used to perform dynamical analysis taking into account large mesh displacements. Analysing the vibration of microsystems is a fundamental issues in the design of a broad range of sensors and actuators. The state of the art currently consists in using staggered procedures to compute quasi-static configurations based on the iteration between a structural model loaded by electrostatic forces and an electrostatic model defined on a domain following the deformation of the structure. Staggered iteration then leads to a static equilibrium position. Performing a perturbation analysis around the static equilibrium yields the electromechanical linearized stiffness needed for computing the eigenfrequencies. Obviously, performing the perturbation analysis to evaluate the tangent stiffness for every degree of freedom leads to very high computing costs and therefore onlythe tangent stiffness associated with presumed modes (typically some purely structural modes) are computed. Such a procedure can lead to important inaccuracies for designs where the electrostatic coupling is not quasi-uniform. In our work, we have developed a fully coupled electro-mechanical formulation that allows to find static equilibrium positions in a non-staggered way and which provides fully consistent tangent stiffness matrices for vibration analysis. The efficiency of the approach will be illustrated on modes of micro-electromechanical devices. The results obtained indicate that using this approach pull-in can be computed very accurately and at low computational cost. Also the coupled electromechanical modes obtained in the vicinity of equilibrium positions can be significantly different from the approximations obtained using a structural reduction at forehand. Numerical results are checked against analytical results where appropriate. The formulation developed for the strongly coupled electromechanical problem allows consistent vibration analysis of the system and yields more accurate vibration eigenmodes and frequencies than the classical staggered approaches. A second interest of the coupled tangent matrix is the computation of the dynamical behaviour of the coupled problem when we apply suddenly a voltage to the electrodes. Even under the pull-in voltage, the overshoot of the dynamical response may reduce the distance between the plate so that the electric force becomes dominant and the plates stick together. This phenomenon is called the dynamical pull-in. We will also treat it in this research. [less ▲]

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See detailDynamical clustering in driven granular gas
Opsomer, Eric ULg; Ludewig, François ULg; Vandewalle, Nicolas ULg

in Europhysics Letters [=EPL] (2012), 99

Driven granular gases present rich dynamical behaviors. Due to inelastic collisions, particles may form dense and slow regions. These clusters emerge naturally during a cooling phenomenon but another ... [more ▼]

Driven granular gases present rich dynamical behaviors. Due to inelastic collisions, particles may form dense and slow regions. These clusters emerge naturally during a cooling phenomenon but another dynamical clustering is observed when the system is continuously excited. In this paper, the physical processes that trigger the transition from a granular gas to a dynamical cluster are evidenced through numerical simulations. At the granular scale, the transition is evidenced by the observation of caging effects. At the scale of the system, the transition is emphasized by density fluctuations. Physical arguments, based on relaxation times, provide an analytical prediction for the edge between dynamical regimes. [less ▲]

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See detailA dynamical energy-based hysteresis model for iron loss calculation in laminated cores
Steentjes, S.; Henrotte, F.; Geuzaine, Christophe ULg et al

in International Journal of Numerical Modelling (2014), 27(3), 433-443

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See detailDynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753
Briquet, Maryline ULg; Korhonen, H.; González, J. F. et al

in Astronomy and Astrophysics (2010), 511

<BR /> Aims: We gathered about 100 high-resolution spectra of three typical HgMn (mercury-manganese) stars, <ASTROBJ>HD 11753</ASTROBJ>, <ASTROBJ>HD 53244</ASTROBJ>, and <ASTROBJ>HD 221507</ASTROBJ>, to ... [more ▼]

<BR /> Aims: We gathered about 100 high-resolution spectra of three typical HgMn (mercury-manganese) stars, <ASTROBJ>HD 11753</ASTROBJ>, <ASTROBJ>HD 53244</ASTROBJ>, and <ASTROBJ>HD 221507</ASTROBJ>, to search for slowly pulsating B-like pulsations and surface inhomogeneous distribution of various chemical elements. <BR /> Methods: Classical frequency analysis methods were used to detect line profile variability and to determine the variation period. Doppler imaging reconstruction was performed to obtain abundance maps of chemical elements on the stellar surface. <BR /> Results: For <ASTROBJ>HD 11753</ASTROBJ>, which is the star with the most pronounced variability, distinct spectral line profile changes were detected for Ti, Sr, Y, Zr, and Hg, whereas for <ASTROBJ>HD 53244</ASTROBJ> and <ASTROBJ>HD 221507</ASTROBJ> the most variable line profiles belong to the elements Hg and Y, respectively. We derived rotation periods for all three stars from the variations of radial velocities and equivalent widths of spectral lines belonging to inhomogeneously distributed elements: P[SUB]rot[/SUB] (<ASTROBJ>HD 11753</ASTROBJ>) = 9.54 d, P[SUB]rot[/SUB] (<ASTROBJ>HD 53244</ASTROBJ>) = 6.16 d, and P[SUB]rot[/SUB] (<ASTROBJ>HD 221507</ASTROBJ>) = 1.93 d. For <ASTROBJ>HD 11753</ASTROBJ> the Doppler imaging technique was applied to derive the distribution of the most variable elements Ti, Sr, and Y using two datasets separated by ~65 days. Results of Doppler imaging reconstruction revealed noticeable changes in the surface distributions of Ti II, Sr II, and Y II between the datasets, indicating the hitherto not well understood physical processes in stars with radiative envelopes that cause a rather fast dynamical chemical spot evolution. Based on observations obtained with the CORALIE Echelle Spectrograph on the 1.2-m Euler Swiss telescope, situated at La Silla, Chile.Postdoctoral Fellow of the Fund for Scientific Research, Flanders. [less ▲]

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Peer Reviewed
See detailA dynamical model with hysteresis for the homogenization of ferromagnetic laminated cores
Henrotte, F.; Niyonzima, Innocent ULg; Steentjes, S. et al

in Proceedings of the 7th European Conference on Numerical Methods in Electromagnetism (NUMELEC2012) (2012, July)

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See detailDynamical Modeling of the Deep Impact Dust Ejecta Cloud
Bonev, T.; Ageorges, N.; Bagnulo, S. et al

in Käufl, H. U.; Sterken, C. (Eds.) Deep Impact as a World Observatory Event: Synergies in Space, Time, and Wavelength (2009)

The collision of Deep Impact with comet 9P/Tempel 1 generated a bright cloud of dust which dissipated during several days after the impact. The brightness variations of this cloud and the changes of its ... [more ▼]

The collision of Deep Impact with comet 9P/Tempel 1 generated a bright cloud of dust which dissipated during several days after the impact. The brightness variations of this cloud and the changes of its position and shape are governed by the physical properties of the dust grains. We use a Monte Carlo model to describe the evolution of the post-impact dust plume. The results of our dynamical simulations are compared to the data obtained with FORS2footnote{FORS stands for \underline{FO}cal Reducer and low dispersion Spectrograph for the Very Large Telescope (VLT) of the European Southern Observatory (ESO).} to derive the particle size distribution and the total amount of material contained in the dust ejecta cloud. [less ▲]

Detailed reference viewed: 17 (2 ULg)