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See detailCollective motion and oscillator synchronization
Sepulchre, Rodolphe ULiege; Paley, Derek; Leonard, Naomi

in Cooperative Control (2005)

This paper studies connections between phase models of coupled oscillators and kinematic models of groups of self-propelled particles. These connections are exploited in the analysis and design of ... [more ▼]

This paper studies connections between phase models of coupled oscillators and kinematic models of groups of self-propelled particles. These connections are exploited in the analysis and design of feedback control laws for the individuals that stabilize collective motions for the group. [less ▲]

Detailed reference viewed: 38 (4 ULiège)
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See detailCollective motion, sensor networks, and ocean sampling
Leonard, Naomi Ehrich; Paley, Derek; Lekien, François et al

in Proceedings of the IEEE (2007), 95(1), 48-74

This paper addresses the design of mobile sensor networks for optimal data collection. The development is strongly motivated by the application to adaptive ocean sampling for an autonomous ocean observing ... [more ▼]

This paper addresses the design of mobile sensor networks for optimal data collection. The development is strongly motivated by the application to adaptive ocean sampling for an autonomous ocean observing and prediction system. A performance metric, used to derive optimal paths for the network of mobile sensors, defines the optimal data set as one which minimizes error in a model estimate of the sampled field. Feedback control laws are presented that stably coordinate sensors on structured tracks that have been optimized over a minimal set of parameters. Optimal, closed-loop solutions are computed in a number of low-dimensional cases to illustrate the methodology. Robustness of the performance to the influence of a steady flow field on relatively slow-moving mobile sensors is also explored. [less ▲]

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See detailCollective Motion: Bistability and Trajectory Tracking
Paley, Derek; Leonard, Naomi; Sepulchre, Rodolphe ULiege

in Proceedings of the 43rd IEEE Conference on Decision and Control (2004, December)

This paper presents analysis and application of steering control laws for a network of self-propelled, planar particles. We explore together the two stably controlled group motions, parallel motion and ... [more ▼]

This paper presents analysis and application of steering control laws for a network of self-propelled, planar particles. We explore together the two stably controlled group motions, parallel motion and circular motion, for modeling and design purposes. We show that a previously considered control law simultaneously stabilizes both parallel and circular group motion, leading to bistability and hysteresis. We also present behavior primitives that enable piecewise-linear network trajectory tracking. [less ▲]

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See detailCollective optimization over average quantities
Scardovi, Luca; Sepulchre, Rodolphe ULiege

in Proceedings of the 45th IEEE Conference on Decision and Control (2006)

This paper addresses the design of algorithms for the collective optimization of a cost function defined over average quantities in the presence of limited communication. We argue that several meaningful ... [more ▼]

This paper addresses the design of algorithms for the collective optimization of a cost function defined over average quantities in the presence of limited communication. We argue that several meaningful collective optimization problems can be formulated in this way. As an application of the proposed approach, we propose a novel algorithm that achieves synchronization or balancing in phase models of coupled oscillators under mild connectedness assumptions on the (possibly time-varying and unidirectional) communication graphs. [less ▲]

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See detailCollective Post-traumatic Disorders, Residual Resources, and an Extensive Context of Trust: Creating a Network in a Refugee Camp in Former Yugoslavia
Lemaire, Jean Marie; Despret, Vinciane ULiege

in International Journal of Mental Health (2001), 30(2), 22-26

Between 1993 and 1996, at the request of Médecins Sans Frontières, Belgium, a "pilot project for network therapy centered on families" was designed for, and developed in, two refugee and displaced persons ... [more ▼]

Between 1993 and 1996, at the request of Médecins Sans Frontières, Belgium, a "pilot project for network therapy centered on families" was designed for, and developed in, two refugee and displaced persons camps during the war ravaging former Yugoslavia. These two facilities housed approximately a thousand families, most of whom had lost one or more members and were suffering from very serious trauma. We decided to accompany our intervention with a dual process of evaluation. During the preliminary stage of this evaluation, the coordinator met with some of the families to ask for their help in supplying information concerning their needs and developing the most appropriate intervention. [less ▲]

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See detailCollective pulsational velocity broadening due to gravity modes as a physical explanation for macroturbulence in hot massive stars
Aerts, C.; Puls, J.; Godart, Mélanie ULiege et al

in Astronomy and Astrophysics (2009), 508

Aims. We aimed at finding a physical explanation for the occurrence of macroturbulence in the atmospheres of hot massive stars, a phenomenon found in observations for more than a decade but that remains ... [more ▼]

Aims. We aimed at finding a physical explanation for the occurrence of macroturbulence in the atmospheres of hot massive stars, a phenomenon found in observations for more than a decade but that remains unexplained.<BR /> Methods: We computed time series of line profiles for evolved massive stars broadened by rotation and by hundreds of low-amplitude nonradial gravity-mode pulsations which are predicted to be excited for evolved massive stars.<BR /> Results: In general, line profiles based on macrotubulent broadening can mimic those subject to pulsational broadening. In several cases, though, good fits require macroturbulent velocities that pass the speed of sound for realistic pulsation amplitudes. Moreover, we find that the rotation velocity can be seriously underestimated by using a simple parameter description for macroturbulence rather than an appropriate pulsational model description to fit the line profiles.<BR /> Conclusions: We conclude that macroturbulence is a likely signature of the collective effect of pulsations. We provide line diagnostics and their typical values to decide whether or not pulsational broadening is present in observed line profiles, as well as a procedure to avoid an inaccurate estimation of the rotation velocity. [less ▲]

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See detailCollective Redress in Multiple Perspectives the challenges of integrating competition law, consumer law and the construction of a European judicial area
Sibony, Anne-Lise ULiege

Scientific conference (2011, April 07)

Collective redress ought to be looked at from several different perspectives: that of competition law, that of consumer law and that of building a European judicial area. This paper looks at the ... [more ▼]

Collective redress ought to be looked at from several different perspectives: that of competition law, that of consumer law and that of building a European judicial area. This paper looks at the challengenges posed by the necessity to hold all three perspective together. [less ▲]

Detailed reference viewed: 53 (7 ULiège)
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See detailCollective Retrieval hy Autonomous Rohots
Meyer, Patrick ULiege

Conference (2004)

Detailed reference viewed: 21 (2 ULiège)
See detailCollective spontaneous emission with quantized atomic motion
Damanet, François ULiege; Braun, Daniel; Martin, John ULiege

Scientific conference (2016, May 09)

Detailed reference viewed: 15 (5 ULiège)
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See detailCollective vortex behaviors: diversity, proximate, and ultimate causes of circular animal group movements
Delcourt, Johann ULiege; Bode, W.F. Nikolaï; Denoël, Mathieu ULiege

in Quarterly Review of Biology (2016), 91(1), 1-24

Ant mill, caterpillar circle, bat doughnut, amphibian vortex, duck swirl, and fish torus are different names for rotating circular animal formations, where individuals turn around a common center. These ... [more ▼]

Ant mill, caterpillar circle, bat doughnut, amphibian vortex, duck swirl, and fish torus are different names for rotating circular animal formations, where individuals turn around a common center. These “collective vortex behaviors” occur at different group sizes from pairs to several million individuals and have been reported in a large number of organisms, from bacteria to vertebrates, including humans. However, to date, no comprehensive review and synthesis of the literature on vortex behaviors has been conducted. Here, we review the state of the art of the proximate and ultimate causes of vortex behaviors. The ubiquity of this behavioral phenomenon could suggest common causes or fundamental underlying principles across contexts. However, we find that a variety of proximate mechanisms give rise to vortex behaviors. We highlight the potential benefits of collective vortex behaviors to individuals involved in them. For example, in some species, vortices increase feeding efficiency and could give protection against predators. It has also been argued that vortices could improve collective decision making and information transfer. We highlight gaps in our understanding of these ubiquitous behavioral phenomena and discuss future directions for research in vortex studies. [less ▲]

Detailed reference viewed: 194 (33 ULiège)
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See detailCollectors of Japanese Art in belgium : between exotism and scholarship
Bawin, Julie ULiege

in Oriental Fascination. 1889-1915. The Japonisme in Belgium (2008)

Detailed reference viewed: 42 (10 ULiège)
See detailLes colles auto-adhésives
MAINJOT, Amélie ULiege

Conference (2009, December)

Detailed reference viewed: 12 (0 ULiège)
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See detailCollider aspects of flavor physics at high Q
Lari, T.; Pape, L.; Porod, W. et al

in European Physical Journal C -- Particles & Fields (2008), 57(1-2), 183-307

This chapter of the 'Flavor in the era of LHC' workshop report discusses flavor-related issues in the production and decays of heavy states at the LHC at high momentum transfer Q, both from the ... [more ▼]

This chapter of the 'Flavor in the era of LHC' workshop report discusses flavor-related issues in the production and decays of heavy states at the LHC at high momentum transfer Q, both from the experimental and the theoretical perspective. We review top quark physics, and discuss the flavor aspects of several extensions of the standard model, such as supersymmetry, little Higgs models or models with extra dimensions. This includes discovery aspects, as well as the measurement of several properties of these heavy states. We also present publicly available computational tools related to this topic. © Springer-Verlag / Società Italiana di Fisica 2008. [less ▲]

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See detailColliding particles carrying nonzero orbital angular momentum
Ivanov, Igor ULiege

in Physical Review. D : Particles and Fields (2011), 83(9), 093001

Photons carrying nonzero orbital angular momentum (twisted photons) are well-known in optics. Recently, using Compton backscattering to boost optical twisted photons to high energies was suggested ... [more ▼]

Photons carrying nonzero orbital angular momentum (twisted photons) are well-known in optics. Recently, using Compton backscattering to boost optical twisted photons to high energies was suggested. Twisted electrons in the intermediate energy range have also been produced recently. Thus, collisions involving energetic twisted particles seem to be feasible and represent a new tool in high-energy physics. Here we discuss some generic features of scattering processes involving twisted particles in the initial and/or final state. In order to avoid additional complications arising from nontrivial polarization states, we focus here on scalar fields only. We show that processes involving twisted particles allow one to perform a Fourier analysis of the plane-wave cross section with respect to the azimuthal angles of the initial particles. In addition, using twisted states, one can probe the autocorrelation function of the amplitude, which is inaccessible in the plane-wave collisions. Finally, we discuss prospects for experimental study of these effects. [less ▲]

Detailed reference viewed: 14 (1 ULiège)
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See detailColliding Wind Signatures in Early-Type Binaries
Rauw, Grégor ULiege

in Revista Mexicana de Astronomia y Astrofisica Conference Series (2008, August 01)

Observations of early-type binaries not only allow us to establish the fundamental properties of massive stars in a model-independent fashion, but furthermore provide important information on the ... [more ▼]

Observations of early-type binaries not only allow us to establish the fundamental properties of massive stars in a model-independent fashion, but furthermore provide important information on the interactions of their stellar winds. The signatures of wind-wind interactions have been found over a broad range of wavelengths and energies, from the radio domain to X-rays and possibly gamma-rays. In this review, I discuss some results of the study of wind interactions in Wolf-Rayet and O-star binaries. [less ▲]

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See detailColliding-wind binaries as non-thermal X-ray emitters: an observational investigation from XMM-Newton to next generation X-ray observatories
De Becker, Michaël ULiege

Poster (2007, December)

The investigation of massive stars in the radio domain revealed about 25 years ago that some of them are synchrotron emitters, showing that these objects are able to accelerate particles up to ... [more ▼]

The investigation of massive stars in the radio domain revealed about 25 years ago that some of them are synchrotron emitters, showing that these objects are able to accelerate particles up to relativistic velocities. In this context, non-thermal emission processes such as inverse Compton scattering are expected to be at work in the high-energy domain. For this reason, an observational campaign devoted to the X-ray investigation of non-thermal radio emitters has been carried out with XMM-Newton. However, considering the rather strong thermal X-ray emission from these systems below 10 keV, XMM-Newton does not appear to be the ideal observatory to detect their putative non-thermal X-rays. As a consequence, the advent of next generation X-ray observatories with a bandpass extending significantly above 10 keV (SIMBOL-X, XEUS, NEXT) is expected to provide important results related to the non-thermal high-energy emission from colliding-wind binaries and their capability to accelerate particles. [less ▲]

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See detailColliding-winds in massive star binaries: expectations from radio to gamma-rays
De Becker, Michaël ULiege

Conference (2010, December 02)

Detailed reference viewed: 17 (2 ULiège)
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See detailCollimator Effects in High Resolution X-ray Computed Tomography
Verly, Jacques ULiege

in IEEE Transactions on Medical Imaging (1982), MI-1(2), 122-136

Detailed reference viewed: 7 (2 ULiège)