Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
See detailOn the Model Validation in Nonlinear structural Dynamics,
Kerschen, Gaëtan ULg

Doctoral thesis (2002)

Detailed reference viewed: 59 (12 ULg)
Full Text
Peer Reviewed
See detailON THE MODELING OF ADHESIVE CONTACT AND STICTION FAILURE IN MICRO-SWITCHES
Wu, Ling ULg; Noels, Ludovic ULg; Golinval, Jean-Claude ULg

in Ouisse (FEMTO-ST – ENSMM, France); Deü (CNAM, FR), J.F. (Eds.) MEDYNA 2013 Proceedings (2013, April)

Undesirable stiction, which results from contact between surfaces, is a major failure mode in micro-switches. Indeed the adhesive forces can become so important that the two surfaces remain permanently ... [more ▼]

Undesirable stiction, which results from contact between surfaces, is a major failure mode in micro-switches. Indeed the adhesive forces can become so important that the two surfaces remain permanently glued, limiting the life-time of the MEMS. This is especially true when contact happens between surfaces where elasto-plastic asperities deform permanently until the surfaces reach plastic accommodation, increasing the surface forces. To predict this behavior, a micro adhesive-contact model is developed, which accounts for the surfaces topography evolutions during elasto-plastic contacts. This model can be used at a higher scale to study the MEMS behavior, and thus its life-time. For illustration purpose, an electrostatic-structural analysis is performed on a micro-switch. [less ▲]

Detailed reference viewed: 28 (6 ULg)
Full Text
Peer Reviewed
See detailOn the modeling of convective drying tests on soil samples in non-isothermal conditions
Gerard, Pierre ULg; Léonard, Angélique ULg; Charlier, Robert ULg et al

in Tsotsas, E.; Metzger, T.; Peglow, M. (Eds.) Proceedings of IDS 2010 - Drying 2010 (2010, October)

Detailed reference viewed: 43 (13 ULg)
Peer Reviewed
See detailOn the modelling of compressed long plates related to sheet-section behaviour
Hofmeyer, H.; Jaspart, Jean-Pierre ULg

in Proceedings of the Fifth International Conference on Thin-Walled Structures (2008)

Detailed reference viewed: 9 (0 ULg)
Full Text
Peer Reviewed
See detailOn the modelling of contact problems with friction by the finite element method.
Charlier, Robert ULg; Godinas, André; Cescotto, Serge ULg

in Proc. 8th Conf. on SMIRT (1985, August)

Detailed reference viewed: 18 (1 ULg)
Peer Reviewed
See detailOn the modelling of tridimensional contact with friction problems in context of large displacements problems
Charlier, Robert ULg; Habraken, Anne ULg

in Proc. of the 2nd Int. Conf. on Numerical Methods in Industrial Forming Processes (1986, August)

Detailed reference viewed: 11 (0 ULg)
Full Text
Peer Reviewed
See detailOn the Motion of Trapped Particles in the Vicinity of Corotation Centers
Beaugé, C.; Lemaitre, Anne; Jancart, Sylvie ULg

in Celestial Mechanics and Dynamical Astronomy (1999), 73

In the present paper we analyse the motion of a massless particle during the capture process in an exterior mean-motion resonance under the effects of an external dissipative force. In particular, we ... [more ▼]

In the present paper we analyse the motion of a massless particle during the capture process in an exterior mean-motion resonance under the effects of an external dissipative force. In particular, we study the orbital evolution from its initial approach to the commensurability up to the final nesting place in the periodic orbit around the equilibrium solution. [less ▲]

Detailed reference viewed: 4 (0 ULg)
Full Text
Peer Reviewed
See detailOn the motion of trapped particles in the vicinity of corotation centers
Beaugé, C.; Lemaitre, Anne; Jancart, Sylvie ULg

in Ferraz-Mello, S. (Ed.) Impact of Modern Dynamics in Astronomy (1999)

In this presentation we revisit the analytical determination of the corotation solutions of the restricted planar three-body problem under the effects of a Stokes drag. Previous calculations by different ... [more ▼]

In this presentation we revisit the analytical determination of the corotation solutions of the restricted planar three-body problem under the effects of a Stokes drag. Previous calculations by different authors, and using different external dissipative forces, have always shown significant quantitative errors of the models with respect to the numerical values. Up to date no concrete explanation has been obtained for this discrepancy. We show that the origin of these errors lies not only in the modelization of the gravitational forces (i.e. disturbing function) but in the averaging process of the variational equations. A second-order averaging is developed based on a Lie transform method (Kamel, 1969). With it we can calculate new equilibrium solutions with a greatly improved accuracy. In a second part, this same perturbation method is applied to study the periodic orbits (i.e. limit cycles) which describe the motion of the particles around the averaged corotational solutions. We show how analytical approximations of these cycles can be obtained through the inverse transformation of the averaging process itself. In all cases, we present comparisons with numerical simulations of the exact equations. [less ▲]

Detailed reference viewed: 16 (0 ULg)
Full Text
Peer Reviewed
See detailOn the mtDNA restriction patterns variation of the Iberian wood mouse (Apodemus sylvaticus). Comparison with other west Mediterranean populations.
Michaux, Johan ULg; Libois, Roland ULg; Ramalhinho, M. G. et al

in Hereditas (1998), 129(3), 187-94

In previous studies, the presence of three main lineages of wood mice mtDNA was described in western Europe: a first one distributed from the Pyrenees to Scandinavia. a Thyrrenian one occurring in ... [more ▼]

In previous studies, the presence of three main lineages of wood mice mtDNA was described in western Europe: a first one distributed from the Pyrenees to Scandinavia. a Thyrrenian one occurring in peninsular Italy, Elba, Corsica and Sardinia and a third one restricted to Sicily and Marettimo. Do the Iberian wood mice belong to one of these lineages? In order to answer this question, animals were trapped all over the Iberian peninsula (11 sites) as well as in three of the Balearic islands. Comparisons with specimens from the above mentioned lineages were made. From 158 animals trapped in 30 sites, 78 different mtDNA restriction patterns were obtained and compared using the NEI and LI index ((Nei M and Li WH, (1979). Mathematical model for studying genetic variation in terms of restriction endonucleases. Proc. Natl. Acad. Sci. USA 76: 5269-5273) of nucleotide divergence. A neighbour-joining tree, with a specimen of Apodemus flavicollis as outgroup, was then computed from the similarity matrix. Apodemus flavicollis is well separated from all the A. sylvaticus and all the Iberian restriction patterns are clustered with those of continental France, showing a great similarity level between the Iberian and north-west European animals. This group is well separated from the Sicilian and from the Tyrrhenian ones. These results suggest that the Pyrenees are not a biogeographic barrier for the wood mouse and that the postglacial recolonisation of western Europe by that species has its origin in populations which, during the latest Ice age, were living in refuges situated in southern France or in the Iberian peninsula. Because the Balearic restriction patterns are clustered in a lineage joining Iberian pattern at a low divergence level, we suggest that their origin is continental Spain or southern France. [less ▲]

Detailed reference viewed: 14 (3 ULg)
Full Text
See detailOn the multiplicity of the non-thermal radio emitters 9 Sgr and HD 168112
Rauw, Grégor ULg; Sana, H.; Gosset, Eric ULg et al

in Massive Stars and High-Energy Emission in OB Associations (2005, November)

We discuss the first results of our ongoing optical spectroscopic monitoring campaign of the two O-type stars 9 Sgr and HD 168112. Both objects display a non-thermal radio emission and were considered as ... [more ▼]

We discuss the first results of our ongoing optical spectroscopic monitoring campaign of the two O-type stars 9 Sgr and HD 168112. Both objects display a non-thermal radio emission and were considered as single stars. Based on a large set of high-resolution spectra, we find that 9 Sgr is clearly an eccentric SB2 binary with an orbital period of several years. On the other hand, no evidence for radial velocity variations attributable to binary motion is found in our spectra of HD 168112. [less ▲]

Detailed reference viewed: 20 (1 ULg)
Full Text
Peer Reviewed
See detailOn the multiplicity of the O-star Cyg OB2#8a and its contribution to the gamma-ray source 3EG J2033+4118
De Becker, Michaël ULg; Rauw, Grégor ULg; Swings, Jean-Pierre ULg

in Astrophysics & Space Science (2005), 297(1-4), 291-298

We present the results of an intensive spectroscopic campaign in the optical waveband revealing that Cyg OB2 # 8A is an O6+ O5.5 binary system with a period of about 21.9 days. Cyg OB2 # 8A is a bright X ... [more ▼]

We present the results of an intensive spectroscopic campaign in the optical waveband revealing that Cyg OB2 # 8A is an O6+ O5.5 binary system with a period of about 21.9 days. Cyg OB2 # 8A is a bright X-ray source, as well as a non-thermal radio emitter. We discuss the binarity of this star in the framework of a campaign devoted to the study of non-thermal emitters, from the radio waveband to gamma-rays. In this context, we attribute the non-thermal radio emission from this star to a population of relativistic electrons, accelerated by the shock of the wind-wind collision. These relativistic electrons could also be responsible for a putative gamma-ray emission through inverse Compton scattering of photospheric UV photons, thus contributing to the yet unidentified EGRET source 3EG J2033+ 4118. [less ▲]

Detailed reference viewed: 13 (4 ULg)
Full Text
Peer Reviewed
See detailOn the multivariate nature of brain metabolic impairment in Alzheimer’s disease
Salmon, Eric ULg; Kerrouche, Nacer; Perani, Daniela et al

in Neurobiology of Aging (2009), 30

We used principal component analysis to decompose functional images of patients with AD in orthogonal ensembles of brain regions with maximal metabolic covariance. Three principal components explained 38 ... [more ▼]

We used principal component analysis to decompose functional images of patients with AD in orthogonal ensembles of brain regions with maximal metabolic covariance. Three principal components explained 38% of the total variance in a large sample of FDG-PET images obtained in 225 AD patients. One functional ensemble (PC2) included limbic structures from Papez's circuit (medial temporal regions, posterior and anterior cingulate cortex, thalamus); its disruption in AD patients was related to episodic memory impairment. Another principal component (PC1) illustrated major metabolic variance in posterior cerebral cortices, and patients' scores were correlated to instrumental functions (language and visuospatial abilities). PC3 comprised frontal, parietal, temporal and posteromedial (posterior cingulate and precuneus) cortices, and patients' scores were related to executive dysfunction and global cognitive impairment. The three main metabolic covariance networks converged in the posterior cingulate area that showed complex relationships with medial temporal structures within each PC. Individual AD scores were distributed as a continuum along PC axes: an individual combination of scores would determine specific clinical symptoms in each patient. [less ▲]

Detailed reference viewed: 154 (21 ULg)
Full Text
Peer Reviewed
See detailOn the nature of the hard X-ray source IGR J2018+4043
Bykov, Andrei Mikhailovich; Krassilchtchikov, Alexandre Mikhailovich; Uvarov, Yuri Alexandrovich et al

in Astrophysical Journal (2006), 649(1, Part 2), 21-24

We found a very likely counterpart to the recently discovered hard X-ray source IGR J2018 + 4043 in the multiwavelength observations of the source field. The source, originally discovered in the 20-40 keV ... [more ▼]

We found a very likely counterpart to the recently discovered hard X-ray source IGR J2018 + 4043 in the multiwavelength observations of the source field. The source, originally discovered in the 20-40 keV band, is now confidently detected also in the 40-80 keV band, with a flux of (1.4 +/- 0.4) x 10(-11) ergs cm(-2) s(-1). A 5 ks Swift observation of the IGR J2018 + 4043 field revealed a hard pointlike source with an observed 0.5-10 keV flux of 3.4(-0.8)(+0.7) x 10(-12) ergs cm(-2) s(-1) (90% confidence level) at alpha = 20(h)18(m)38(s).55, delta = +40 degrees 41'00.4" (with a 4".2 uncertainty). The combined Swift-INTEGRAL spectrum can be described by an absorbed power-law model with photon index Gamma = 1.3 +/- 0.2 and N-H = 6.1(-2.2)(+3.3) x 10(22) cm(-2). In archival optical and infrared data we found a slightly extended and highly absorbed object at the Swift source position. There is also an extended VLA 1.4 GHz source peaked at a beamwidth distance from the optical and X-ray positions. The observed morphology and multiwavelength spectra of IGR J2018 + 4043 are consistent with those expected for an obscured accreting object, i.e., an AGN or a Galactic X-ray binary. The identification suggests possible connection of IGR J2018 + 4043 to the bright gamma-ray source GEV J2020 + 4023 detected by COS B and CGRO EGRET. [less ▲]

Detailed reference viewed: 76 (6 ULg)
Full Text
See detailOn the nature of the spectral and photometric periodic variability of apparently single Wolf-Rayet stars
Morel, Thierry ULg

in The Observatory (1999), 119

Not Available

Detailed reference viewed: 11 (1 ULg)
Full Text
Peer Reviewed
See detailOn the necessity and biological significance of threshold-free regulon prediction outputs
Rigali, Sébastien ULg; Nivelle, Renaud; Tocquin, Pierre ULg

in Molecular Biosystems (2015)

The in silico prediction of cis-acting elements in a genome is an efficient way to quickly obtain an overview of the biological processes controlled by a trans-acting factor, and connections between ... [more ▼]

The in silico prediction of cis-acting elements in a genome is an efficient way to quickly obtain an overview of the biological processes controlled by a trans-acting factor, and connections between regulatory networks. Several regulon prediction web tools are available, designed to identify DNA motifs predicted to be bound by transcription factors using position weight matrix-based algorithms. In this paper we expose and discuss the conflicting objectives of software creators (bioinformaticians) and software users (biologists), who aim for reliable and exhaustive prediction outputs, respectively. Software makers, concerned with providing tools that minimise the number of false positive hits, often impose a stringent threshold score for a sequence to be included in the list of the putative cis-acting sites. This rigidity eventually results in the identification of strongly reliable but largely straightforward sites, i.e. those associated with genes already anticipated to be targeted by the studied transcription factor. Importantly, this biased identification of strongly bound sequences contrasts with the biological reality where, in many circumstances, a weak DNA-protein interaction is required for the appropriate gene's expression. We show here a series of transcriptionally controlled systems involving weakly bound cis-acting elements that could never have been discovered because of the policy of preventing software users from modifying the screening parameters. Proposing only trustworthy prediction outputs thus prevents biologists from fully utilising their knowledge background and deciding to analyse statistically irrelevant hits that could nonetheless be potentially involved in subtle, unexpected, though essential cis-trans relationships. [less ▲]

Detailed reference viewed: 8 (1 ULg)
Full Text
See detailOn the necessity to consider varying parameters in the land subsidence computations
Dassargues, Alain ULg

in Barends, F. B. J.; Brouwer, F. J. J.; Schröder, F. H. (Eds.) Land Subsidence (Proc. of the Vth Int. Symp.) (1995)

Detailed reference viewed: 16 (4 ULg)
Full Text
Peer Reviewed
See detailOn the necessity to use three-dimensional groundwater models for describing impact of drought conditions on streamflow regimes
Dassargues, Alain ULg; Maréchal, J. C.; Carabin, Guy et al

in Hydrological Extremes : Understanding, Predicting, Mitigating (1999)

Detailed reference viewed: 24 (7 ULg)
Full Text
Peer Reviewed
See detailOn the Number of Abelian Bordered Words
Rampersad, Narad; Rigo, Michel ULg; Salimov, Pavel ULg

in Lecture Notes in Computer Science (2013), 7907

In the literature, many bijections between (labeled) Motzkin paths and various other combinatorial objects are studied. We consider abelian (un)bordered words and show the connection with irreducible ... [more ▼]

In the literature, many bijections between (labeled) Motzkin paths and various other combinatorial objects are studied. We consider abelian (un)bordered words and show the connection with irreducible symmetric Motzkin paths and paths in Z not returning to the origin. This study can be extended to abelian unbordered words over an arbitrary alphabet and we derive expressions to compute the number of these words. In particular, over a 3-letter alphabet, the connection with paths in the triangular lattice is made. Finally, we study the lengths of the abelian unbordered factors occurring in the Thue--Morse word. [less ▲]

Detailed reference viewed: 59 (13 ULg)