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See detailOnline least-squares policy iteration for reinforcement learning control
Busoniu, Lucian; Ernst, Damien ULg; De Schutter, Bart et al

in Proceedings of the 2010 American Control Conference (2010)

Reinforcement learning is a promising paradigm for learning optimal control. We consider policy iteration (PI) algorithms for reinforcement learning, which iteratively evaluate and improve control ... [more ▼]

Reinforcement learning is a promising paradigm for learning optimal control. We consider policy iteration (PI) algorithms for reinforcement learning, which iteratively evaluate and improve control policies. State-of-the-art, least-squares techniques for policy evaluation are sample-efficient and have relaxed convergence requirements. However, they are typically used in offline PI, whereas a central goal of reinforcement learning is to develop online algorithms. Therefore, we propose an online PI algorithm that evaluates policies with the so-called least-squares temporal difference for Q-functions (LSTD-Q). The crucial difference between this online least-squares policy iteration (LSPI) algorithm and its offline counterpart is that, in the online case, policy improvements must be performed once every few state transitions, using only an incomplete evaluation of the current policy. In an extensive experimental evaluation, online LSPI is found to work well for a wide range of its parameters, and to learn successfully in a real-time example. Online LSPI also compares favorably with offline LSPI and with a different flavor of online PI, which instead of LSTD-Q employs another least-squares method for policy evaluation. [less ▲]

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See detailOnline monitoring of heterogeneous polymerizations in supercritical carbon dioxide by Raman spectroscopy
Grignard, Bruno ULg; Gilbert, Bernard ULg; Malherbe, Cédric ULg et al

in Chemphyschem : A European Journal of Chemical Physics and Physical Chemistry (2012), 13(11), 2666-2670

A novel setup is described to monitor the kinetics of homogeneous and heterogeneous reactions online using Raman spectroscopy under high pressure. The arrangement is based on a high-pressure reactor ... [more ▼]

A novel setup is described to monitor the kinetics of homogeneous and heterogeneous reactions online using Raman spectroscopy under high pressure. The arrangement is based on a high-pressure reactor equipped with a sapphire window in combination with a mobile probe that allows the collection of the back-scattered Raman signal at 360°. [less ▲]

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See detailOnline monitoring of the interaction of balls and slurry with the Sensomag ®
Köttgen, Axel; Leroy, Sophie ULg; Bastin, David ULg et al

Poster (2012, December 10)

Presentation of Optimag Project results. Optimag aims to optimize the ball milling operations through the use of an embarked sensor, called the Sensomag, and developed by Magotteaux to monitor in real ... [more ▼]

Presentation of Optimag Project results. Optimag aims to optimize the ball milling operations through the use of an embarked sensor, called the Sensomag, and developed by Magotteaux to monitor in real time the position of the slurry and the grinding balls. [less ▲]

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See detailOnline Sparse Bandit for Card Games
Lupien St-Pierre, David ULg; Louveaux, Quentin ULg; Teytaud, Olivier

in Advance in Computer Games (2011)

Finding an approximation of a Nash equilibria in matrix games is an important topic that reaches beyond the strict application to matrix games. A bandit algorithm commonly used to approximate a Nash ... [more ▼]

Finding an approximation of a Nash equilibria in matrix games is an important topic that reaches beyond the strict application to matrix games. A bandit algorithm commonly used to approximate a Nash equilibrium is EXP3. However, the solution to many problems is often sparse, yet EXP3 inherently fails to exploit this property. To the knowledge of the authors, there exist only an offline truncation to tackle such issue. In this paper, we propose a variation of EXP3 to exploit the fact that solution is sparse by dynamically removing arms; the resulting algorithm empirically performs better than previous versions. We apply the resulting algorithm to a MCTS program for the Urban Rivals card game. [less ▲]

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See detailOnline travel service quality: The role of pre-transaction services
Van Riel, Allard ULg; Semeijn, Janjaap; Pauwels, Pieter

in Total Quality Management & Business Excellence (2004), 15(4), 475-493

Detailed reference viewed: 35 (0 ULg)
See detailOnline Voltage Security Assessment in the Hellenic Interconnected System
Vournas, Costas; Christoforidis, George; Van Cutsem, Thierry ULg

in Savulescu, Savu (Ed.) Real-Time Stability Assessment in Modern Power System Control Centers (2009)

Detailed reference viewed: 61 (1 ULg)
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See detailOnly Connect: An Interview with Caryl Phillips on Foreigners
Ledent, Bénédicte ULg; Phillips, Caryl

in Schatteman, Renée T. (Ed.) Conversations with Caryl Phillips (2009)

Detailed reference viewed: 91 (1 ULg)
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See detailOnomastique grecque et histoire romaine: quelques réflexions à propos d'une concordance d'Appien
Famerie, Etienne ULg

in Revue. Informatique et statistiques appliquées aux sciences humaines (1990), 26

Survey of different problems of lemmatization with Roman proper names (of persons, of places) transposed in Greek by Appian

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See detailOnroerende verhuur: meer of minder Europa ?
Peeters, Bart ULg

in Tijdschrift voor Fiscaal Recht (2012)

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See detailThe onset of NPQ and Deltamu(H)+ upon illumination of tobacco plants studied through the influence of mitochondrial electron transport.
Cardol, Pierre ULg; De Paepe, Rosine; Franck, Fabrice ULg et al

in Biochimica et Biophysica Acta (2010), 1797(2), 177-88

The relationship between the development of photoprotective mechanisms (non-photochemical quenching, NPQ), the generation of the electrochemical proton gradient in the chloroplast and the capacity to ... [more ▼]

The relationship between the development of photoprotective mechanisms (non-photochemical quenching, NPQ), the generation of the electrochemical proton gradient in the chloroplast and the capacity to assimilate CO(2) was studied in tobacco dark-adapted leaves at the onset of illumination with low light. These conditions induce the generation of a transient NPQ, which relaxes in the light in parallel with the activation of the Calvin cycle. Wild-type plants were compared with a CMSII mitochondrial mutant, which lacks the respiratory complex I and shows a delayed activation of photosynthesis. In the mutant, a slower onset of photosynthesis was mirrored by a decreased capacity to develop NPQ. This correlates with a reduced efficiency to reroute electrons at the PSI reducing side towards cyclic electron flow around PSI and/or other alternative acceptor pools, and with a smaller ability to generate a proton motive force in the light. Altogether, these data illustrate the tight relationship existing between the capacity to evacuate excess electrons accumulated in the intersystem carriers and the capacity to dissipate excess photons during a dark to light transition. These data also underline the essential role of respiration in modulating the photoprotective response in dark-adapted leaves, by poising the cellular redox state. [less ▲]

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See detailThe onset of photometric variability in red giant stars.
Jorissen, A.; Mowlavi, N.; Sterken, C. et al

in Astronomy and Astrophysics (1997), 324

The onset of variability in red giant stars is studied from the data collected by the `Long-Term Photometry of Variables' project which operates at ESO (La Silla) since 1982. The differential nature of ... [more ▼]

The onset of variability in red giant stars is studied from the data collected by the `Long-Term Photometry of Variables' project which operates at ESO (La Silla) since 1982. The differential nature of the observations combined with a multi-night reduction algorithm enables to study the variability of over 50 red giants with an accuracy of the order of 2 to 3 millimagnitudes on time scales ranging from days to years. All red giants with spectral types late G to early K (i.e. b-y~0.6-0.8) are stable at the level Ï _y_<6millimag (where Ï _y_ is the standard deviation of the Stroemgren y magnitude). Red giants with later spectral types are all variable, and it is found that the minimum variability level Ï _y, min_ increases with increasing b-y, thus defining a minimum-variability boundary. The new data obtained in this paper reveal that the time scale of the associated variability increases with increasing b-y (and thus amplitude), and that the stability of this time scale improves concomitantly. More precisely, irregular variations on time scales of 5 to 10-days (and Ï _y_~7millimag) characterize red giants with b-y~1.0, whereas the variations (with Ï _y_~100millimag) become more regular with periods of the order of 50d for red giants with b-y~1.3. A radial-velocity jitter (of the order of 1.5km/s r.m.s.) is associated with this photometric variability, and suggests that stellar oscillations may be responsible for the observed variations. [less ▲]

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See detailOnset of thermal ripples at the interface of an evaporating liquid under a flow of inert gas
Scheid, B.; Margerit, J.; Iorio, C. S. et al

in Experiments in Fluids (2012), 52

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See detailOnset Time of Neuromuscular Block and Intubating Conditions: Influence of Different Stimulation Patterns
Hans, Pol ULg; Dewé, Walthère ULg; Albert, Adelin ULg

in Acta Anaesthesiologica Belgica (1997), 48(1), 15-21

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See detailOntogenesis and functional aspects of oxytocin and vasopressin gene expression in the thymus network
Hansenne, Isabelle ULg; Rasier, G.; Pequeux, Christel ULg et al

in Journal of Neuroimmunology (2005), 158(1-2), 67-75

Ontogenesis of oxytocin (OT) and vasopressin (VP) gene expression and function were investigated in murine thymus. OT and VP transcripts were detected in the thymus on embryonic days 13 and 15 ... [more ▼]

Ontogenesis of oxytocin (OT) and vasopressin (VP) gene expression and function were investigated in murine thymus. OT and VP transcripts were detected in the thymus on embryonic days 13 and 15, respectively. Corresponding messenger RNAs were evidenced in thymic epithelial cells by in situ hybridization with a neurophysin probe. From all OT and VP receptors, only OTR was expressed by all T-cell subsets, while V1bR was found in double positive and single positive CD8 cells. In fetal thymic organ cultures, OTR antagonist d[DTyr(Et)(2), Thr(4)]OVT increased early apoptosis of CD8 cells, while V1bR antagonist (Sanofi SSR 149415) inhibited T-cell differentiation, and favored CD8 T-cell commitment. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailOntogenesis of behavioral sensitization and conditioned place preference induced by psychostimulants in laboratory rodents
Tirelli, Ezio ULg; Laviola, Giovanni; Adriani, Walter

in Neuroscience & Biobehavioral Reviews (2003), 27(1-2), 163-178

The present review deals mainly with the ontogenesis of two important phenomena involved in vulnerability to several neuropsychiatric disorders, namely with drug-induced sensitization (both contextual and ... [more ▼]

The present review deals mainly with the ontogenesis of two important phenomena involved in vulnerability to several neuropsychiatric disorders, namely with drug-induced sensitization (both contextual and non-contextual) and with conditioned place preference. The term 'infancy' covers the first three postnatal weeks during development in rats and mice. Conversely, the term 'adolescence' may cover the whole postnatal period ranging from weaning (PND 21) to adulthood (at least PND 60) or specifically the period around the onset of puberty (animals aged 33-44 days). Recent studies in rats demonstrated that the establishment of a context-dependent sensitization appears during the first (for repeated drug administration) or during the second (for a single drug administration) postnatal week. However, the memory of drug-context association is transient in developing pups (lasting one or two days following the drug pretreatment). The long-term retention of drug-context associations matures progressively, and is complete by the third week of postnatal life. Finally, those mechanisms responsible for an adult-like profile of context-independent pharmacological sensitization appear later during ontogenesis, being mature by the fourth week of postnatal life. Another set of experiments extended this ontogenetic characterization by comparing adolescent and adult mice. When compared to the latter, the former subjects exhibit a greater amphetamine-induced locomotor sensitization, almost no sensitization of aversive stereotyped behaviors, and a less marked place conditioning. The strength of the drug-induced place conditioning was also directly compared with the unconditioned novelty-seeking drive. In conclusion, neonatal rats are able to show a relatively short-lasting retention of sensitized drug effects (short-term sensitization), whereas the ability to exhibit relatively long-lasting sensitized effects matures progressively during infancy (long-term sensitization). On the other hand, adolescent mice show a reduced sensitization of drug-induced psychotic symptoms, together with a more marked sensitization of arousing and euphorigenic properties of the drug and a reduced incentive memory of its hedonic effects. These age-related changes do imply very different degrees of vulnerability to drug addiction and several other neuropsychiatric disorders. (C) 2003 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailOntogenetic aspects of individual differences in behavioral responsiveness to cocaine in rats
Michel, Alexa ULg; Tirelli, Ezio ULg

in Behavioural Pharmacology (1996), 10(Suppl.), 211-212

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See detailOntogenetic determinism of colour polymorphism in a coral reef fish, Chrysiptera brownriggii (Pomacentridae)
Frederich, Bruno ULg; Brié, Christophe; Santos, Raphael et al

Poster (2008, October)

The determinism of ontogenetic colour changes induced by environmental factors is poorly understood in marine fishes, especially in coral ecosystems. The present study, conducted at the Rangiroa Atoll ... [more ▼]

The determinism of ontogenetic colour changes induced by environmental factors is poorly understood in marine fishes, especially in coral ecosystems. The present study, conducted at the Rangiroa Atoll (French Polynesia) explored the effects of fish density and brightness/darkness condition (type of background) on colour determination during the ontogeny of a territorial damselfish Chrysiptera brownriggii (Bennett 1828). In this species, larvae always colonize the reef (settlement) in a yellow morph, while juveniles and adults can display two distinct colour-patterns: yellow and dark brown. Our experiments in aquaria showed that a significant higher proportion of C. brownriggii larvae turned into the brown morph in a dark condition during a period of 5 and 15 days (70-100% of brown morph induction) just after reef settlement. A significant positive effect of fish density inducing a brown colour morph was also highlighted. After a first colour induction, reversibility experiments illustrated that juveniles can change their colour morph anew after a 5-day period. Although a shift from brown to yellow morph seemed to be more limited. In the dark condition, yellow adults did not change their colour after a 5-day period. Our results showed that the colour dimorphism in C. brownriggii should be density-dependent. The period of sensitivity seems to last throughout the post-settlement period. We suggest that the yellow morph in C. brownriggii can be viewed as a paedomorphic trait. Overall, our results reveal that a darkness/lightness environment and fish density are environmental cues related to colour determinism in the polyphenetic C. brownriggii. [less ▲]

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