ORBi Open Repository and Bibliography
In may 2007, the ULg's Administrative Board (joined in June 2007 by the FUSAGx) decided to create an institutional repository and defined a strong institutional self-archiving policy to increase the visibility, accessibility and impact of the University's publications (Board's decision).
This decision led to the official launch, in November 2008, of the ORBi platform including both the Academic Bibliography and the Institutional Repository of the Wallonia-Europe University Academy.
Engineering, computing & technology => Multidisciplinary, general & others
Mostrando recursos 1 - 20 de 1.208
Workshops as tools for creative collaboration: finding a balance between facilitation and auto-organization - Elsen, Catherine; Cornet, Adeline; Antoine, Mélanie
This paper analyses four settings of so-called collaborative “creative workshops” (their methods, logistics, regulation processes) and provide peepholes on their respective features, with the informed goals of defining criteria for comparison, finding shared essence and distinctive characteristics. Key aspects such as time, facilitation and auto-organization shape a “creative continuum” that formalizes how creativity can be stimulated and how participants might collaboratively develop creative behaviors.
Lyapunov-based sufficient conditions for exponential stability in hybrid systems - Teel, Andrew; Forni, Fulvio; Zaccarian, Luca
Lyapunov-based sufficient conditions for exponential stability in hybrid systems are presented. The focus is on converting non-strict Lyapunov conditions, having certain observability properties, into strict Lyapunov conditions for exponential stability. Both local and global results are considered. The utility of the results is illustrated through an example.
Follow the bouncing ball: global results on tracking and state estimation with impacts - Forni, Fulvio; Teel, Andrew; Zaccarian, Luca
In this paper we formulate tracking and state- estimation problems of a translating mass in a polyhedral billiard as a stabilization problem for a suitable set. Due to the discontinuous trajectories arising from the impacts, we use hybrid systems stability analysis tools to establish the results. Using a novel concept of mirrored images of the target mass we prove that 1) a tracking control algorithm, and 2) an observer algorithm guarantee global exponential stability results for specific classes of polyhedral billiards, including rectangles. Moreover, we combine these two algorithms within dynamic controllers that guarantee global output feedback tracking. The results...
Reference mirroring for control with impacts - Forni, Fulvio; Teel, Andrew; Zaccarian, Luca
We illustrate a peculiar concept of mirrored reference to address reference tracking control systems for plants subject to impacts. The idea is based on the constructions of artiﬁcial references corresponding to suitable reﬂections of the actual reference performed with respect to the impacting surfaces. We illustrate the application of this idea to reference tracking and state observation for a number of examples of control systems subject to impacts: a one-dimensional hammer hitting a surface, a two-dimensional Newton’s cradle, a two-dimensional mass moving in a planar equilateral triangle and a mass moving in an n-dimensional polyhedral region. For each one of...
Inverse dynamics of serial and parallel underactuated multibody systems using a DAE optimal control approach - Guimaraes Bastos Junior, Guaraci; Seifried, Robert; Bruls, Olivier
The inverse dynamics analysis of underactuated multibody systems aims at determining
the control inputs in order to track a prescribed trajectory. This paper studies the inverse dynamics of non-minimum phase underactuated multibody systems with serial and parallel planar topology, e.g. for end-effector control of flexible manipulators or manipulators with passive joints. Unlike for minimum phase systems, the inverse dynamics of non-minimum phase systems cannot be solved by adding trajectory constraints (servoconstraints) to the equations of motion and applying a forward time integration. Indeed, the inverse dynamics of a non-minimum phase system is known to be non-causal, which means that the control...
Design and validation of a real-time spiking-neural-network decoder for brain–machine interfaces - Dethier, Julie; Nuyujukian, Paul; Ryu, Stephen I; Shenoy, Krishna V.; Boahen, Kwabena
Objective. Cortically-controlled motor prostheses aim to restore functions lost to neurological disease and injury. Several proof of concept demonstrations have shown encouraging results, but barriers to clinical translation still remain. In particular, intracortical prostheses must satisfy stringent power dissipation constraints so as not to damage cortex. Approach. One possible solution is to use ultra-low power neuromorphic chips to decode neural signals for these intracortical implants. The first step is to explore in simulation the feasibility of translating decoding algorithms for brain–machine interface (BMI) applications into spiking neural networks (SNNs). Main results. Here we demonstrate the validity of the approach by...
MOSAIC: a multiscale model of osteogenesis and sprouting angiogenesis with lateral inhibition of endothelial cells. - Carlier, Aurélie; Geris, Liesbet; Bentley, Katie; Carmeliet, Geert; Carmeliet, Peter; Van Oosterwyck, Hans
The healing of a fracture depends largely on the development of a new blood vessel network (angiogenesis) in the callus. During angiogenesis tip cells lead the developing sprout in response to extracellular signals, amongst which vascular endothelial growth factor (VEGF) is critical. In order to ensure a correct development of the vasculature, the balance between stalk and tip cell phenotypes must be tightly controlled, which is primarily achieved by the Dll4-Notch1 signaling pathway. This study presents a novel multiscale model of osteogenesis and sprouting angiogenesis, incorporating lateral inhibition of endothelial cells (further denoted MOSAIC model) through Dll4-Notch1 signaling, and applies...
Modeling and Prediction of Time-Varying Environmental Data Using Advanced Bayesian Methods - Mansouri, Majdi; Dumont, Benjamin; Destain, Marie-France
The problem of state/parameter estimation represents a key issue in crop models which are nonlinear, non-Gaussian and include a large number of parameters. The prediction errors are often important due to uncertainties in the equations, the input variables, and the parameters. The measurements needed to run the model (input data), to perform calibration and validation are sometimes not numerous or known with some uncertainty.
In these cases, estimating the state variables and/or parameters from easily obtained measurements can be extremely useful. In this work, we address the problem of modeling and prediction of leaf area index and soil moisture (LSM) using...
High-speed imaging use to predict spray retention on barley leaves - Boukhalfa, Hassina dite Hafida; Massinon, Mathieu; Lebeau, Frédéric
Laboratory studies were conducted to validate the effectiveness of the use of high-speed imaging method to replace chemical nalysis by fluoremetrie. Measurements were performed with a high-speed camera coupled with a retro-LED lighting. Size and velocity of the drop were extracted by image analysis. Drop impact types were determined by the operator. Drops were produced with a flat-fan nozzle mounted on a movable ramp. Two surfactants (Break-Thru® S240 and Li700 ®) were sprayed on BBCH 12 barley leaves to highlight the effect of the reduction of surface tension. Relative volume proportions were computed within of an energy scale divided into...
Résonance stochastique dans les modèles neuronaux de type Hodgkin-Huxley : Etude et Application - Collard, Anne
En 1981, Benzi et al ont introduit le phénomène de résonance stochastique pour expliquer leurs observations sur les changements climatiques de notre planète. Depuis, ce phénomène a été largement étudié dans toutes sortes de domaines, dont la neurophysiologie.
La résonance stochastique est un phénomène qui peut se manifester dans des systèmes non-linéaires, lorsqu'une entrée peut être amplifiée (optimisée) grâce à la présence de bruit dans le système. La présence d'une barrière énergétique, d'un seuil à franchir,… dans le système empêche généralement les signaux de faible amplitude d'être transmis. La présence de bruit permettra d'amplifier l'entrée faible et provoquera des transitions du...