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See detailMaximum entropy approach to the identification of stochastic reduced-order models of nonlinear dynamical systems
Arnst, Maarten ULg; Ghanem, Roger; Masri, Sami

in Aeronautical Journal (2010), 114(1160), 637-650

Data-driven methodologies based on the restoring force method have been developed over the past few decades for building predictive reduced-order models (ROMs) of nonlinear dynamical systems. These ... [more ▼]

Data-driven methodologies based on the restoring force method have been developed over the past few decades for building predictive reduced-order models (ROMs) of nonlinear dynamical systems. These methodologies involve fitting a polynomial expansion of the restoring force in the dominant state variables to observed states of the system. ROMs obtained in this way are usually prone to errors and uncertainties due to the approximate nature of the polynomial expansion and experimental limitations. We develop in this article a stochastic methodology that endows these errors and uncertainties with a probabilistic structure in order to obtain a quantitative description of the proximity between the ROM and the system that it purports to represent. Specifically, we propose an entropy maximization procedure for constructing a multi-variate probability distribution for the coefficients of power-series expansions of restoring forces. An illustration in stochastic aeroelastic stability analysis is provided to demonstrate the proposed framework. [less ▲]

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See detailMaximum entropy at intermediate anthropogenic dynamics
Vranken, Isabelle ULg; Bogaert, Jan ULg

in Jones, Bruce; Fu, Bojie (Eds.) The 8th World congress of the International Association of Landscape Ecology: Proceedings, Beijing, August 18-23, 2011 (2011, August 20)

Landscape entropy represents heterogeneity within a landscape (Renyi, 1961; Bogaert et al., 2005). Previous researches found increasing values of entropy by studying a limited number of zones increasingly ... [more ▼]

Landscape entropy represents heterogeneity within a landscape (Renyi, 1961; Bogaert et al., 2005). Previous researches found increasing values of entropy by studying a limited number of zones increasingly affected by anthropogenic effect (O’Neill et al., 1988; Bogaert et al., 2005). The present research aims to generalise the relationship between anthropogenic effect and landscape entropy, with a further goal of linking these concepts to overall biodiversity. 16 study zones from classified LANDSAT TM scenes and Africover maps presenting different anthropogenic effect intensities have been used (Djibu et al., 2008; Bamba et al., 2010; Barima et al., 2010; Munyemba, 2010; Vranken et al., 2011). Simpson's H diversity index based on class number has been used for entropy measurement (Renyi, 1961; Pielou, 1975; Shannon and Weaver, 1963). 1-H has been retained to get the relationship between the index and diversity directly proportional. For anthropogenic effect measurement, O’Neill’s U disturbance index, quotient between anthropogenic and natural areas, has been used (O’Neill et al., 1988). Log H has been retained to linearise the exponential relationship between the index and anthropogenic effect. Correlation between those variables has then been analysed. The scatter plot of the 16 study zones shows a Gaussian curve (Fig. 1) presenting maximal landscape entropy at intermediate anthropogenic effect. This distribution has been modelled by a second order polynomial regression with determination coefficient and significance. This phenomenon has been interpreted in terms of spatial transformation processes (Bogaert et al., 2004) and linked to the habitat heterogeneity hypothesis (Tews, 2004), as well as the intermediate disturbance hypothesis (Connell, 1978; Lindenmayer and Brugman, 2005). [less ▲]

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See detailMaximum likelihood range dependence compensation for STAP
Neyt, Xavier; Acheroy, Marc; Verly, Jacques ULg

Conference (2007)

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See detailTHE MAXIMUM-ENTROPY PRODUCTION PRINCIPLE IN CLIMATE MODELS - APPLICATION TO THE FAINT YOUNG SUN PARADOX
Gérard, Jean-Claude ULg; DELCOURT, D.; François, Louis ULg

in Quarterly Journal Of The Royal Meteorological Society (1990), 116(495), 1123-1132

Current theories of stellar evolution imply that the solar luminosity was 25-30% less than at present during early phases of the Earth's history. The response of the global annual climate to changes of ... [more ▼]

Current theories of stellar evolution imply that the solar luminosity was 25-30% less than at present during early phases of the Earth's history. The response of the global annual climate to changes of the solar input is examined using the maximum entropy production (MEP) principle and a zonal energy balance model including ice-albedo feedback. It is shown that this formulation reproduces satisfactorily the present meridional heat flux and latitudinal temperature distributions. It is found that the model predicts that the efficiency of the meridional heat transport decreases for low values of the solar constant. Consequently, if the solar irradiance is lowered, a progressive development of the polar caps and a decrease of the global surface temperature are obtained without major irreversibility in the system. A comparison with a similar model including diffusive heat transport formalism shows that the value of the critical solar luminosity causing a global glaciation is decreased when the meridional heat fluxes are determined by the MEP principle. [less ▲]

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See detailMaximum-likelihood Based Range-dependence Compensation for Coherent Multistatic STAP-based Radar
Neyt, Xavier; Acheroy, Marc; Verly, Jacques ULg

Conference (2007)

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See detailMaximum-likelihood reconstruction with ordered subsets in bone SPECT
Blocklet, Didier; Seret, Alain ULg; Popa, Niculaie et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1999), 40(12), 1978-1984

This study was aimed at determining whether the ordered-subset expectation maximum (OSEM) is more effective than filtered backprojection (FBP) for bone SPECT in the routine clinical context. Methods ... [more ▼]

This study was aimed at determining whether the ordered-subset expectation maximum (OSEM) is more effective than filtered backprojection (FBP) for bone SPECT in the routine clinical context. Methods. Fifty-seven consecutive bone SPECT studies were analyzed. They included pelvic and lumbar spine, thoraco lumbar spine, head and neck, feet and shoulders. A 64-projection SPECT study was acquired over 360° by single-head cameras 2–3h after the injection of 750 MBq 99mTc-methylene diphosphonate. Three observers compared the OSEM and FBP reconstructed images. Results. Streak artifacts, always present with FBP, were rarely generated with the OSEM. When present (n = 24), artifacts associated with negative values near hyperactivities in FBP were not generated with the OSEM in 67% of the cases (n = 16), permitting a satisfactory interpretation of these regions. In half of the other cases (17%, n = 4/24), interpretation was precluded. In only one case did the three observers agree that more hyperactivities were seen with the OSEM. Ninety-six percent of the OSEM pictures were superior or equal to FBP for anatomic resolution and were clearly better in 12% of the cases. The extent of the lesion with the OSEM seemed better or equally defined in 96% and clearly better in 14% of the cases. The low-activity regions were better or equally visualized in all cases and were clearly better seen in 23% of the cases. The quality of the pictures was found to be better or superior with the OSEM in 98% of the cases and definitely better in 65% of the cases. Conclusion: Replacement of FBP by the OSEM in bone SPECT would be beneficial to clinical practice. [less ▲]

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See detailMaxwell rigidity and topological constraints in amorphous phase-change networks
Micoulaut, M.; Otjacques, C.; Raty, Jean-Yves ULg et al

in AIP Conference Proceedings (2011), 1393

By analyzing first-principles molecular-dynamics simulations of different telluride amorphous networks, we develop a method for the enumeration of radial and angular topological constraints, and show that ... [more ▼]

By analyzing first-principles molecular-dynamics simulations of different telluride amorphous networks, we develop a method for the enumeration of radial and angular topological constraints, and show that the phase diagram of the most popular system Ge-Sb-Te can be split into two compositional elastic phases: a tellurium rich flexible phase and a stressed rigid phase that contains most of the materials used in phase-change applications. This sound atomic scale insight should open new avenues for the understanding of phase-change materials and other complex amorphous materials from the viewpoint of rigidity. [less ▲]

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See detailThe May 4, 2013 Stellar Occultation by Pluto and Implications for Pluto's Atmosphere
Olkin, Catherine B.; Young, L. A.; Borncamp, D. et al

in Bulletin of the American Astronomical Society (2013, October 01), 45

On May 4 2013, Pluto passed in front of a 14 star and the shadow was well observed from multiple occultation groups. This paper presents results from the three light curves observed at Las Cumbres ... [more ▼]

On May 4 2013, Pluto passed in front of a 14 star and the shadow was well observed from multiple occultation groups. This paper presents results from the three light curves observed at Las Cumbres Observatory Global Telescope Network (LCOGT) from their Cerro Tololo site. The three LCOGT telescopes have 1.0 m apertures and used identical frame-transfer cameras. The cameras currently have a 2 second readout time therefore autonomous observations were scheduled with different exposure times to give good time resolution of the event. We will present results of this occultation and compare occultation results from 1988 to 2013 with volatile transport models. [less ▲]

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See detailMay rare metallophytes benefit from disturbed soils following mining activities ? The case of the Crepidorhopalon tenuis in Katanga (D.R. COngo)
Faucon, Michel Pierre; Parmentier, Ingrid; Collinet, Gilles et al

in Restoration Ecology (2009)

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See detailMay Rare Metallophytes Benefit from Disturbed Soils Following Mining Activity? The Case of the Crepidorhopalon tenuis in Katanga (D. R. Congo)
Faucon, Michel-Pierre; Parmentier, Ingrid; Colinet, Gilles ULg et al

in Restoration Ecology (2011), 19

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See detailThe May-July 1989 Crisis of V348 Sgr
Manfroid, Jean ULg; Houziaux, Léo ULg

in Information Bulletin on Variable Stars (1989), 3375

Not Available

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See detailMaya blue-green pigments found in Calakmul, Mexico: a study by Raman and UV-visible spectroscopy
Moreno, Renata Garcia; Strivay, David ULg; Gilbert, Bernard ULg

in Journal Of Raman Spectroscopy (2008), 39(8), 1050-1056

After more than two decades of fieldwork in the Maya archaeological site of Calakmul, Mexico, numerous remnants of blue and green pigments have been reported on wall paintings, as well as on funerary ... [more ▼]

After more than two decades of fieldwork in the Maya archaeological site of Calakmul, Mexico, numerous remnants of blue and green pigments have been reported on wall paintings, as well as on funerary paraphernalia, such as masks, miniatures and vases. The importance of these pigments is linked to the sacred values that Maya people associate with blue and green colours since pre-Columbian times. These hues symbolise water, and are therefore associated with fertility and regeneration. This paper aims to perform a survey of the blue and green pigments used in the Early Classic and Late Classic periods in Calakmul (300-850 A.D.), in order to have a better understanding of their chemical composition and origin. Analyses were performed on microsamples using Raman and UV-visible spectroscopies to evaluate the possibilities that these techniques can offer in future in situ researches on Mesoamerican archaeological materials and objects. With these analyses, we have documented a large blue-green chromatic palette, which includes the earliest Blue Maya and Green Maya known to date, as well as malachite, pseudomalachite and an unknown-up-to-now blue-green mineral pigment, veszelyite, used specifically for ritual objects. The results indicate a careful selection of imported products and the mastering of a complex ancient Maya pictorial tradition. Copyright (c) 2008 John Wiley & Sons, Ltd. [less ▲]

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See detailThe mayonnaise droplet
Terwagne, Denis ULg; Mack, Nicolas; Dorbolo, Stéphane ULg et al

Poster (2009, March)

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See detailThe mayonnaise droplet
Terwagne, Denis ULg; Gilet, Tristan ULg; Vandewalle, Nicolas ULg et al

Conference (2009, November 23)

A compound drop is made of a millimetric water drop encapsulated by an oil shell. They are obtained by merging one drop of each component (water and oil). Afterwards, they are laid on a high viscosity oil ... [more ▼]

A compound drop is made of a millimetric water drop encapsulated by an oil shell. They are obtained by merging one drop of each component (water and oil). Afterwards, they are laid on a high viscosity oil bath which is vertically vibrated. When the forcing acceleration is higher than a given threshold, compound drops can bounce on the surface. We show that above a second threshold some oil contained in the shell enters in the inner water droplet. In a second experiment, we drop the compound droplet on the oil bath at rest. We can determine the range of impact speed in which capillary waves developed on the surface are able to generate an oil drop (coming from the shell) in the water drop. When the bouncing trajectories of the droplets are analyzed a correlation between the emulsion threshold and the static analysis can be made. [less ▲]

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See detailThe mayonnaise droplet
Terwagne, Denis ULg; Gilet, Tristan ULg; Vandewalle, Nicolas ULg et al

Poster (2009, September)

Compound drops are made of a millimetric water drop encapsulated by an oil shell. They are laid on a high viscosity oil bath which is vertically vibrated. When the forcing acceleration is higher than a ... [more ▼]

Compound drops are made of a millimetric water drop encapsulated by an oil shell. They are laid on a high viscosity oil bath which is vertically vibrated. When the forcing acceleration is higher than a given threshold, compound drops can bounce on the surface. We show that above an another threshold a double emulsion occurs in the drop. We measured this emulsion threshold for various size and water/oil volume ratio of the compound drop. [less ▲]

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See detailThe mayonnaise droplet
Terwagne, Denis ULg; Mack, Nicolas; Dorbolo, Stéphane ULg et al

in Chaos (2009)

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See detailThe mazer physics
Bastin, Thierry ULg

Conference (2003)

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See detailMazindol in the treatment of Parkinson's disease.
Delwaide, P. J.; Schoenen, Jean ULg; Martinelli, P.

in Archives of Neurology (1983), 40(13), 788-90

Mazindol, a drug that blocks the reuptake of dopamine, was studied in the treatment of Parkinson's disease in both a pilot study (12 patients) and a controlled trial (11 patients). The patients had stage ... [more ▼]

Mazindol, a drug that blocks the reuptake of dopamine, was studied in the treatment of Parkinson's disease in both a pilot study (12 patients) and a controlled trial (11 patients). The patients had stage II or III disease, according to the classification of Hoehn and Yahr. Both studies showed that mazindol possessed anti-parkinsonian properties and that the improvement was statistically significant. The therapeutic effect was moderate, but could be of value for patients in the early stages of the disease. The drug was well tolerated; only two patients had side effects. [less ▲]

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