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See detailDylan Thomas en chansons
Delville, Michel ULg

Article for general public (2010)

Detailed reference viewed: 17 (1 ULg)
See detailDynamath
Jaminon, Martine ULg; Wallenborn, Jean; Spitz, Carole et al

Learning material (2011)

Plaquette de l'exposition "Dynamath : les maths à la portée de tous"

Detailed reference viewed: 18 (4 ULg)
Peer Reviewed
See detailDynamic Accelerated Failure Time Model with Endogeneity and Heterogeneity: a Control Function approach
Tiwari, Amaresh Kumar ULg; Heuchenne, Cédric ULg

Conference (2013, August)

We develop a control function method to estimate an Accelerated Failure Time (AFT) model with multiple states, where we account for state dependence, heterogeneity, and endogeneity of covariates. In ... [more ▼]

We develop a control function method to estimate an Accelerated Failure Time (AFT) model with multiple states, where we account for state dependence, heterogeneity, and endogeneity of covariates. In accounting for state dependency in the structural AFT model and endogeneity of covariates through control functions, we are faced with predetermined covariates in the first stage treatment choice equation, which is a system of regressions for panel data. A concentrated likelihood method has been proposed to estimate a system of regressions with predetermined covariates. The control functions are based on "expected a posteriori" (EAP) values of the correlated random effects, and unlike alternative control function approaches, our approach allows for general instruments. [less ▲]

Detailed reference viewed: 17 (0 ULg)
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See detailDynamic analysis and preliminary design of twin-cylinder engines for clean propulsion systems
Louvigny, Yannick ULg; Vanoverschelde, Nicolas; Janssen, Guy et al

Conference (2009, July 02)

Facing environmental and energy challenges, automotive industry has to improve the fuel economy of vehicles and to reduce their polluting emissions. In this particular context, small twin-cylinder engines ... [more ▼]

Facing environmental and energy challenges, automotive industry has to improve the fuel economy of vehicles and to reduce their polluting emissions. In this particular context, small twin-cylinder engines regain interest for using in urban cars or as prime movers in hybrid electric cars. One difficulty with engine having few cylinders (three or less) comes from the balancing of the inertia forces created by the moving parts. Several models (from simple analytical model to complex flexible multibody simulation) of different configurations of twin-cylinder engine are developed. These models allow computing the inertia forces and moments generated by the engines and computing the strains and stresses of engine components. An important step is the engine balancing by modification of the crankshaft counterweights or by addition of balance shafts. The effect of the gas pressure on the balancing and on the component’s strains and stresses is also modelled. At the end, a comparison of the different configurations of twin-cylinder engine is provided [less ▲]

Detailed reference viewed: 125 (11 ULg)
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See detailA dynamic analysis of higher-comoment risk premiums in Hedge Fund returns
Lambert, Marie ULg

in Journal of Derivatives and Hedge Funds (2012), 18(1), 73-84

Hedge funds display a strong non-linear payoff structure because of the use of highly dynamic trading strategies. This article examines the relevance of using higherorder comoment equity risk premiums ... [more ▼]

Hedge funds display a strong non-linear payoff structure because of the use of highly dynamic trading strategies. This article examines the relevance of using higherorder comoment equity risk premiums implied in the United States and the emerging markets for capturing these return non-linearities. We provide evidence that the higherorder comoment equity risk premiums help in explaining the returns of the different hedge fund strategies from the Hedge Fund Research classification. We perform a dynamic analysis where moment risk exposures are examined separately in up and down markets. We show that hedge fund styles tend to vary their exposures to moment risks according to the market regimes. [less ▲]

Detailed reference viewed: 41 (7 ULg)
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See detailDynamic analysis of microbial behaviour face to envrionmental heterogeneities encountered in large-scale bioreactors
Sunya, Sirichai; Bideaux, Carine; Uribellarea, Jean-Louis et al

in Delvigne, Frank (Ed.) BASE (2011)

Detailed reference viewed: 16 (6 ULg)
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See detailDynamic analysis of the nonlinear behavior of MEMS using the finite element formulation
Rochus, Véronique ULg; Kerschen, Gaëtan ULg; Golinval, Jean-Claude ULg

in ASME International Design Engineering Technical Conferences & Computers and Information in Engineering Conference, Long Beach, 2005 (2005, September)

The dynamic response of a mass-spring model of electrostatically actuated MEMS is analyzed when a voltage step is applied. The dynamics of a clamped-clamped beam representing a micro-bridge system are ... [more ▼]

The dynamic response of a mass-spring model of electrostatically actuated MEMS is analyzed when a voltage step is applied. The dynamics of a clamped-clamped beam representing a micro-bridge system are also considered. To model and simulate the strong coupling between the electric and mechanical fields, a general finite element program has been developed based on a new monolithic formulation. The methodology proposed in this program does not require any iterative numerical scheme based on separate electrostatic and mechanical solvers, respectively. [less ▲]

Detailed reference viewed: 64 (27 ULg)
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See detailDynamic analysis of the self-locking phenomenon in tape spring hinges
Hoffait, Sébastien ULg; Bruls, Olivier ULg; Granville, Didier et al

in Acta Astronautica (2010), 66(7-8), 1125-1132

This paper investigates the dynamic behaviour of tape-spring hinges that are commonly used in space deployable structures. During the deployment of an appendice (e.g. a solar panel or a beam), a tape ... [more ▼]

This paper investigates the dynamic behaviour of tape-spring hinges that are commonly used in space deployable structures. During the deployment of an appendice (e.g. a solar panel or a beam), a tape-spring hinge allows the simultaneous achievement of the actuating, guiding and self-locking functions without friction elements. The proposed finite element model is able to capture buckling and hysteresis phenomena, which have a strong influence on the 3D motion of the system. A detailed analysis of those effects is developed, leading to a physical explanation of the crucial self-locking phenomenon. [less ▲]

Detailed reference viewed: 83 (12 ULg)
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See detailDynamic Analysis Used to Cope with Partial and Temporary Failures
Franssen, Jean-Marc ULg; Gens, Frederic

in Franssen, Jean-Marc; Benichou, Nouredine; Kodur, Venkatesh (Eds.) et al Proceedings of SiF'04: Third International Structures in Fire workshop (2004)

Detailed reference viewed: 62 (2 ULg)
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See detailDynamic And Equilibrium Surface Tensions Of Surfactin Aqueous Solutions
Razafindralambo, Hary ULg; Thonart, Philippe ULg; Paquot, Michel ULg

in Journal of Surfactants and Detergents (2004), 7(1), 41-46

A homologous series of surfactins containing β-hydroxy fatty acids having 13, 14, or 15 carbon atoms were isolated from the supernatant of Bacillus subtilis strain S499 cultures. Their surface-active ... [more ▼]

A homologous series of surfactins containing β-hydroxy fatty acids having 13, 14, or 15 carbon atoms were isolated from the supernatant of Bacillus subtilis strain S499 cultures. Their surface-active properties at the air-water interface were then evaluated. Dynamic surface tension data were analyzed by the relaxation function γt=γm+(γo−γm)/[1+(t/t*)n]. Based on various parameters t*, n, vmax, γm calculated from this equation, the dynamic surface properties of surfactin were found to depend on both bulk concentration and hydrophobic character of the alkyl chain. At low concentrations of surfactin, the dynamic surface tension (γd) decreased with increasing carbon atom number of the surfactin alkyl chain (n=13 to 15). However, at high concentrations, the maximum decrease of 41-4 was achieved by surfactin-C14. In contrast, more strongly hydrophobic alkyl chains in surfactins always enhanced their ability in reducing the equilibrium surface tensions and their aptitude in forming micelles. [less ▲]

Detailed reference viewed: 110 (78 ULg)
See detailDynamic and Mobile GIS: Investigating Changes in Space and Time
Drummond, Jane; Billen, Roland ULg; Joao, Elsa et al

Book published by CRC Press (2007)

Detailed reference viewed: 56 (8 ULg)
See detailDynamic and region specific changes in estrogen production induced by reproductive stimuli.
de Bournonville, Catherine ULg; Dickens, Molly J; Ball, Gregory F et al

Poster (2012, May 04)

Detailed reference viewed: 7 (0 ULg)
See detailDynamic and static aspects of voltage collapse
Van Cutsem, Thierry ULg

in Proc. International Workshop on "Bulk Power System Voltage Phenomena - voltage stability and security" (1988)

Detailed reference viewed: 14 (0 ULg)
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See detailDynamic approach of structural fire calculation with FEM software
Vassart, Olivier; Cajot, Louis-Guy; Franssen, Jean-Marc ULg et al

in Proc. 5th International Conference on Performance-Based Codes and Fire Safety Design Methods (2004)

This paper explains how the dynamic approach has been implemented in the computer software SAFIR in order to cope with temporary and local failures that occured in a step be step static analysis of ... [more ▼]

This paper explains how the dynamic approach has been implemented in the computer software SAFIR in order to cope with temporary and local failures that occured in a step be step static analysis of structures subjected to fire.By means of this recently implemented dynamic algorithm, it’s now possible to simulate the complete failure mechanism, to predict the influence of a local failure on the global behaviour of the structure and to follow eventually the progressive collapse. Therefore the resistance time is now really determined whereas in the past many numerical failure corresponding to local failure were interpreted as resistance time of the whole structure. [less ▲]

Detailed reference viewed: 65 (0 ULg)
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See detailDynamic assessment of severity of illness in pediatric intensive care.
Ruttimann, U E; Albert, Adelin ULg; Pollack, M M et al

in Critical Care Medicine (1986), 14(3), 215-21

Severity of illness in 293 pediatric ICU patients was assessed by a daily estimate of ICU survival. The probability of nonsurvival was obtained by logistic regression analysis, using physiologic stability ... [more ▼]

Severity of illness in 293 pediatric ICU patients was assessed by a daily estimate of ICU survival. The probability of nonsurvival was obtained by logistic regression analysis, using physiologic stability index (PSI) values from previous days as time-dependent covariates. Only PSI values from the previous 2 days gave statistically significant predictions of short-term (less than 24 h) outcome. When the prediction model derived from these data was tested prospectively on a separate set of 345 pediatric patients, there was excellent agreement between observed and predicted short-term mortality. Receiver operating characteristic curves for the 345 patients were statistically equivalent to those originally derived for the 293 patients, and this prediction model had significantly (p less than .025) more accuracy than prediction based on admission PSI. These results indicate that this model for daily risk assessment is statistically reliable and objective, as verified against eventual outcome. In the 345 patients, ICU mortality was predicted with 89% sensitivity and 91% specificity. This prediction model may be used to stratify patient groups for clinical studies, or identify very low-risk patients for potential early ICU discharge. [less ▲]

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See detailDynamic assessment of the floc morphology, bacterial diversity and integron content of an activated sludge reactor processing hospital effluent
Stalder, Thibault; Alrhmoun, Moussab; Louvet, Jean-Noël ULg et al

in Environmental Science & Technology (2013)

The treatment of hospital effluents (HE) is a major concern, as they are suspected of disseminating drugs and antibiotic resistance determinants in the environment. In order to assess HE influence on ... [more ▼]

The treatment of hospital effluents (HE) is a major concern, as they are suspected of disseminating drugs and antibiotic resistance determinants in the environment. In order to assess HE influence on wastewater treatment plant biomass, lab scale conventional activated sludge systems (CAS) were continuously fed with real HE or urban effluent as a control. To gain insights into the main hurdles linked to HE treatment, we conducted a multiparameter study using classical physicochemical characterization, phase contrast and confocal laser 35 scaning microscopy, and molecular biology (i.e. pyrosequencing) tools. HE caused erosion of floc structure and the production of extracellular polymeric substances attributed to the development of floc forming bacteria. Adaptation of the sludge bacterial community to the HE characteristics, thus maintaining the purification performance of the biomass, was observed. Finally, the comparative metagenomic analysis of the CAS showed that HE 40 treatment resulted in an increase of class 1 resistance integrons (RIs) and the introduction of Pseudomonas spp. into the bacterial community. HE treatment did not reduce the CAS process performance; nevertheless it increases the risk of dissemination into the environment of bacterial species and genetic determinants (RIs) involved in antibiotic resistance acquisition. [less ▲]

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See detailDynamic auroral storms on Saturn as observed by the Hubble Space Telescope
Nichols, J. D.; Badman, S. V.; Baines, K. H. et al

in Geophysical Research Letters (2014), 41

We present observations of significant dynamics within two UV auroral storms observed on Saturn using the Hubble Space Telescope in April/May 2013. Specifically, we discuss bursts of auroral emission ... [more ▼]

We present observations of significant dynamics within two UV auroral storms observed on Saturn using the Hubble Space Telescope in April/May 2013. Specifically, we discuss bursts of auroral emission observed at the poleward boundary of a solar wind-induced auroral storm, propagating at ˜330% rigid corotation from near ˜01 h LT toward ˜08 h LT. We suggest that these are indicative of ongoing, bursty reconnection of lobe flux in the magnetotail, providing strong evidence that Saturn's auroral storms are caused by large-scale flux closure. We also discuss the later evolution of a similar storm and show that the emission maps to the trailing region of an energetic neutral atom enhancement. We thus identify the auroral form with the upward field-aligned continuity currents flowing into the associated partial ring current. [less ▲]

Detailed reference viewed: 16 (8 ULg)
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See detailDynamic calibration of Flexiforce sensors for ballistic measurements
Robbe, Cyril ULg; Papy, Alexandre; Nsiampa Ndompetelo, ULg

in Binetruy, Christophe; Boussu, François (Eds.) Recent Advances in TExtile Composites (2010, October 26)

In the field of terminal ballistics, non-invasive force measurements are sometimes needed. The cheap and thin Flexiforce sensors can be used for this purpose with low collateral effects. This paper works ... [more ▼]

In the field of terminal ballistics, non-invasive force measurements are sometimes needed. The cheap and thin Flexiforce sensors can be used for this purpose with low collateral effects. This paper works on the development of a method designed to dynamically calibrate the Flexiforce sensor. The objective is to find a calibration parameter that correlates the Flexiforce output signal, in terms of conductance, to the applied force. The process used to achieve this dynamic calibration is based on a drop test. The principle is to impact the sensor with the falling of a specified mass. The force signal delivered by the Flexiforce sensor is afterwards compared to the signal measured by a reference force sensor that measures the same impact. To further validate this measurement, the impact is applied on a spring, placed directly between the falling mass and the Flexiforce. The deflection of that spring is measured with a high-speed camera. Knowing the spring properties, we can determine the force produced by the spring on the two sensors, and consequently validate the reference measurement. The calibration factor seems independent of the applied force, and follows a normal distribution. Both the frequency of the impact and the contact surface have an influence on the output of the Flexiforce sensor. For that reason the calibration process should use a frequency and a contact surface similar to the considered application. [less ▲]

Detailed reference viewed: 123 (1 ULg)