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See detailGénération automatique d'une base de données de silhouettes humaines au moyen d'un avatar humain tridimensionnel
Pierard, Sébastien ULg

Master's dissertation (2007)

Pour la conception de systèmes de vidéo-surveillance, il est avantageux d’avoir un système de détection automatique d’êtres humains. Certains de ces systèmes sont basés sur la reconnaissance de la forme ... [more ▼]

Pour la conception de systèmes de vidéo-surveillance, il est avantageux d’avoir un système de détection automatique d’êtres humains. Certains de ces systèmes sont basés sur la reconnaissance de la forme de silhouettes humaines. L’utilisation de méthodes d'apprentissage pour la reconnaissance nécessite une base de données de silhouettes humaines, dont il est intéressant d’automatiser la génération. Dans ce travail, nous utilisons un avatar humain tridimensionnel, celui du projet open-source MakeHuman, afin de générer automatiquement la base de données. Le choix des configurations (positions, orientations et poses) à donner à l’avatar pour obtenir une base de données adéquate est central. Dans un premier temps, nous tentons une étude de l’impact de modifications dans le mode tridimensionnel sur la silhouette. Cet impact est quantifié par la distance de Hausdorff. Parmi les modifications envisagées se trouvent le déplacement, la rotation et le changement de pose de l’avatar. Nous espérions déterminer, à partir de ces impacts, les pas par lesquels doivent varier les différents paramètres. Les configurations que doit prendre l’avatar, pour obtenir une base de données suffisamment riche sans être trop volumineuse, seront obtenues en prenant toutes les combinaisons des valeurs des différents paramètres. Le nombre de configurations est exponentiel en le nombre de degrés de liberté, ce qui rend l’approche inutilisable en pratique, même si nous sommes indifférents à la translation et à la mise à l’échelle des silhouettes. Dans un deuxième temps, nous avons opté pour une approche radicalement différente. Cette fois, nous n’espaçons plus les silhouettes, mais les poses. La position de l’avatar est fixée et il ne peut tourner qu’autour de l’axe vertical. Les poses sont choisies en effectuant des tirages aléatoires des différents paramètres. Cette approche aléatoire du problème a mené à l’élaboration d’un nouveau logiciel, Silhouette. Il est écrit en Java et une interface écrite en C lui permet, grâce à Java Native Interface d’exploiter efficacement le moteur de pose de MakeHuman. Parmi les fonctionnalités de Silhouette, notons la possibilité de restreindre les poses à un ensemble voulu, de ne générer que des silhouettes correspondant à des poses licites et d’annoter les silhouettes. Grâce au logiciel mis en place, nous avons été en mesure de générer diverses bases de données. Nous avons étudié l'impact de l'utilisation de celles-ci sur les performances d'un système de détection de personnes existant. Nous obtenons des résultats encourageants, 73% des silhouettes humaines étant correctement détectées. Un raffinement et un paramétrage soigneux de la méthode devraient mener à des résultats excellents. [less ▲]

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See detailEpithelial-mesenchymal transition process in human embryonic stem cells cultured in feeder-free conditions.
Ullmann, U.; In'T Veld, P.; Gilles, Christine ULg et al

in Molecular Human Reproduction (2007), 13(1), 21-32

Feeder-free human embryonic stem cell (hESC) culture is associated with the presence of mesenchymal-like cells appearing at the periphery of the colonies. The aim of this study was to identify this early ... [more ▼]

Feeder-free human embryonic stem cell (hESC) culture is associated with the presence of mesenchymal-like cells appearing at the periphery of the colonies. The aim of this study was to identify this early differentiation process. Long-term feeder-free hESC cultures using matrigel and conditioned medium from mouse and from human origin revealed that the appearance of mesenchymal-like cells was similar regardless of the conditioned medium used. Standard characterization confirmed the preservation of hESC properties, but the feeder-free cultures could not be maintained longer than 37 passages. The early differentiation process was characterized in the short term after switching hESCs cultured on feeders to feeder-free conditions. Transmission electron microscopy showed an epithelium-like structure inside the hESC colonies, whereas the peripheral cells revealed the acquisition of a rather mesenchymal-like phenotype. Immunochemistry analysis showed that cells at the periphery of the colonies had a negative E-cadherin expression and a positive Vimentin expression, suggesting an epithelial–mesenchymal transition (EMT). Nuclear staining of ß-catenin, positive N-cadherin and negative Connexin 43 expression were also found in the mesenchymal-like cell population. After RT–PCR analysis, Slug and Snail, both EMT-related transcription factors, were detected as up-regulated in the mesenchymal-like cell population. Taken together, our data suggest that culturing hESCs in feeder-free conditions enhances an early differentiation process identified as an EMT. [less ▲]

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See detailFuzzy approximation for convergent model-based reinforcement learning
Busoniu, Lucian; Ernst, Damien ULg; Babuska, Robert et al

in Proceedings of the 2007 IEEE International Conference on Fuzzy Systems (FUZZ-IEEE-07) (2007)

Reinforcement learning (RL) is a learning control paradigm that provides well-understood algorithms with good convergence and consistency properties. Unfortunately, these algorithms require that process ... [more ▼]

Reinforcement learning (RL) is a learning control paradigm that provides well-understood algorithms with good convergence and consistency properties. Unfortunately, these algorithms require that process states and control actions take only discrete values. Approximate solutions using fuzzy representations have been proposed in the literature for the case when the states and possibly the actions are continuous. However, the link between these mainly heuristic solutions and the larger body of work on approximate RL, including convergence results, has not been made explicit. In this paper, we propose a fuzzy approximation structure for the Q-value iteration algorithm, and show that the resulting algorithm is convergent. The proof is based on an extension of previous results in approximate RL. We then propose a modi ed, serial version of the algorithm that is guaranteed to converge at least as fast as the original algorithm. An illustrative simulation example is also provided. [less ▲]

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See detailCorrosion patina or intentional patina: Contribution of non-destructive analyses to the surface study of copper based archaeological objects
Mathis, François ULg; Descamps, Sophie; Delange, Elisabeth et al

in Dillmann, Philippe; Piccardo, Paolo; Matthiesen, H. (Eds.) et al Corrosion of metallic heritage artefacts: Investigation, conservation and prediction of long term behaviour (EFC 48) (2007)

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See detailModel predictive control and reinforcement learning as two complementary frameworks
Ernst, Damien ULg; Glavic, Mevludin; Capitanescu, Florin ULg et al

in International Journal of Tomography & Statistics (2007), 6

Model predictive control (MPC) and reinforcement learning (RL) are two popular families of methods to control system dynamics. In their traditional setting, they formulate the control problem as a ... [more ▼]

Model predictive control (MPC) and reinforcement learning (RL) are two popular families of methods to control system dynamics. In their traditional setting, they formulate the control problem as a discrete-time optimal control problem and compute a suboptimal control policy. We present in this paper in a unified framework these two families of methods. We run for MPC and RL algorithms simulations on a benchmark control problem taken from the power system literature and discuss the results obtained. [less ▲]

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See detailDevelopment of atherosclerosis for the vascular surgeon.
Defraigne, Jean-Olivier ULg

in Liapis, C. D. (Ed.) European Manual of Medicine (2007)

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See detailCarte hydrogéologique de Wallonie 1/25000. 68/1-2, Assenois - Anlier, notice explicative.
Bouezmarni, Mohamed ULg; Denne, Pierre; Debbaut, Vincent ULg

Book published by Service public de Wallonie, DGARNE - peer reviewed (2007)

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See detailTeatro, violenza e resistenza in Congo Brazzaville. Il percorso di Dieudonné Niangouna
Jedlowski, Alessandro ULg

Book published by L'Harmattan Italia (2007)

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See detailProsody and foreign language learning
Rasier, Laurent ULg

Conference (2007)

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See detailWhole body vibration in the treatment of fibromyalgia: Influence on muscle performances
Maquet, Didier ULg; Helene, Loic; Demoulin, Christophe ULg et al

in Isokinetics & Exercise Science (2007), 15

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See detailPrevention and treatment of major blood loss
Detry, Olivier ULg; De Roover, Arnaud ULg; Honore, Pierre ULg

in New England Journal of Medicine [=NEJM] (2007), 357(12), 1261-1261

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See detailLiège, Belgium: 50 years of palynology
Steemans, Philippe ULg

Report (2007)

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See detailPréface: promouvoir la réflexion et la recherche sur l'anorexie
Born, Michel ULg

in L'observatoire, les Actes+ (2007)

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See detailNatural dualities for varieties generated by a set of subalgebras of a semi-primal algebra
Mathonet, Pierre ULg; Niederkorn, Philippe; Teheux, Bruno ULg

in Algebra and Discrete Mathematics (2007), (1), 67--85

The main contribution of this paper is the construction of a strong duality for the varieties generated by a set of subalgebras of a semi-primal algebra. We also obtain an axiomatization of the objects of ... [more ▼]

The main contribution of this paper is the construction of a strong duality for the varieties generated by a set of subalgebras of a semi-primal algebra. We also obtain an axiomatization of the objects of the dual category and develop some algebraic consequences (description of the dual of the finite structures and algebras, construction of finitely generated free algebras,. . . ). Eventually, we illustrate this work for the finitely generated varieties of MV-algebras. [less ▲]

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See detailL'assiette du Belge en chiffres
Duquesne, Brigitte ULg

Poster (2007)

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See detailNumerical simulation of semi-solid thixoforming
Koeune, Roxane ULg; Ponthot, Jean-Philippe ULg

in Int. Conf. on Computational Plasticity, COMPLAS IX (2007)

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See detailComment je traite...un uterus didelphe associe a un hemi-vagin borgne
Loumaye, F.; Cheruy, Charlotte ULg; Cristinelli, S. et al

in Revue Médicale de Liège (2007), 62(7-8, Jul-Aug), 480-3

Didelphys uterus with imperforated obstructed hemivagina is a rare condition. Most often, it is diagnosed a few months after the menarche. Hematocolpos, hematometria and sometimes hematosalpinx are ... [more ▼]

Didelphys uterus with imperforated obstructed hemivagina is a rare condition. Most often, it is diagnosed a few months after the menarche. Hematocolpos, hematometria and sometimes hematosalpinx are responsible for pelvic pain and dysmenorrhea. Symptoms can be delayed when a fistulisation from the hematocolpos to permeable contralateral vagina is present. Sometimes, diagnosis is not made before adulthood during an infection of the hematocolpos. Useful additional exams include pelvic ultrasound and, in some cases, MRI, which is the best exam to precisely describe the type of malformation. An ipsilateral agenesia of the kidney is always associated. Hysterography can usually demonstrate the fistulous courses. Treatment consists in a large resection of the vaginal septum in order to allow a permanent drainage of the hemiuterus. A laparoscopy should be performed to check for the presence of associated tubal or pelvic damage. [less ▲]

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