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See detailPowdered lipid nano and microparticles : production and applications
Berton, Amandine; Piel, Géraldine ULg; Evrard, Brigitte ULg

in Recent Patents on Drug Delivery & Formulation (2011), 5(3), 188-200

This review details articles and recent patents in an emerging topic called powdered form of nano- and microparticles. Solid lipid particles were developed in the early 1990s and since, they have been ... [more ▼]

This review details articles and recent patents in an emerging topic called powdered form of nano- and microparticles. Solid lipid particles were developed in the early 1990s and since, they have been considered as promising drug delivery systems, especially in providing a sustained release profile of the encapsulated drug. This kind of drug delivery system has several advantages, due to its physiological composition. It is generally well tolerated by the human body and are relatively stable during storage in comparison with other carriers like liposomes. The description of these powdered lipid particles, their different production processes and their applications are the focus of the article. [less ▲]

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See detailPower indices and the measurement of control in corporate structures
Crama, Yves ULg; Leruth, Luc ULg

E-print/Working paper (2011)

This paper proposes a review of the use of power indices in the corporate governance literature. It places the emphasis on the game-theoretic aspects of this research, but it also addresses some of the ... [more ▼]

This paper proposes a review of the use of power indices in the corporate governance literature. It places the emphasis on the game-theoretic aspects of this research, but it also addresses some of the key issues linked to the specific field of application. [less ▲]

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See detailPower law for the duration of recession and prosperity in Latin American countries
Redelico, F. O.; Proto, A. N.; Ausloos, Marcel ULg

in Physica A: Statistical Mechanics and its Applications (2008), 387(25), 6330-6336

Ormerod and Mounfield [P. Ormerod, C. Mounfield, Power law distribution of duration and magnitude of recessions in capitalist economies: Breakdown of scaling, Physica A 293 (2001) 573] and Ausloos et al ... [more ▼]

Ormerod and Mounfield [P. Ormerod, C. Mounfield, Power law distribution of duration and magnitude of recessions in capitalist economies: Breakdown of scaling, Physica A 293 (2001) 573] and Ausloos et al. [M. Ausloos, J. Mikievvicz, M. Sanglier, The durations of recession and prosperity: Does their distribution follow a power or an exponential law? Physica A 339 (2004) 548] have independently analyzed the duration of recessions for developed countries through the evolution of the GDP in different time windows. It was found that there is a power law governing the duration distribution. We have analyzed data collected from 19 Latin American countries in order to observe whether such results are valid or not for developing countries. The case of prosperity years is also discussed. We observe that the power law of recession time intervals, see Ref. [1], is valid for Latin American countries as well. Thus an interesting point is discovered: the same scaling time is found in the case of recessions for the three data sets (ca. 1 year), and this could represent a universal feature. Other time scale parameters differ significantly from each other. (C) 2008 Elsevier B.V. All rights reserved. [less ▲]

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See detailPower Line conductors self damping : a new approach.
Guérard, Suzanne ULg; Lilien, Jean-Louis ULg

in Proceedings of the 9th International Symposium on Cable Dynamics (2011, October)

Up to now, self damping data generally comes from dynamic tests performed on test spans which length is of the order of some tens of meters. Those tests rely on the assumption that the conductor self ... [more ▼]

Up to now, self damping data generally comes from dynamic tests performed on test spans which length is of the order of some tens of meters. Those tests rely on the assumption that the conductor self damping changes the amplitude of incident and reflected travelling wave. In other words, there are no standing wave within a vibrating conductor and in practice, the amount of self damping is deduced from measurements of vibration amplitudes at adjacent “false vibration nodes”. The corresponding measurements require lots of dexterity and accuracy. This paper investigates the possibility of deducing the self damping properties of power line conductors from a series of tests performed quasi statically on a short prestressed conductor sample. Data recorded by Godinas [1] on 4 m long prestressed conductor samples has been used as an input (the conductors used are made of aluminium alloy, type AMS). This data was obtained by applying a cyclic quasi-static bending moment in the middle of the conductor sample and recording the corresponding strains. The experiment was reproduced at several prestress levels. A mining and analysis of this data has been performed so that in a first time the relationship between moment and curvature can be adequately defined. Then the corresponding internal work has been computed analytically (per integration). Finally a formulation for the self damping per unit length is proposed as a function of the antinode amplitude of vibration, frequency, conductor tension, bending stiffness, mass per unit length plus a special parameter called “b”. The latter parameter has the dimension of energy [J]. The corresponding results are found to be consistent with those deduced from the widely used “power law”, using Noiseux’s exponents [2, 3]. Also, a simplified version of the formula shows that the sensitivity of the self damping to the vibration amplitude, frequency and tension is comparable to that found by others authors using another self damping measurement technique [1], but with the difference that in this case, the exponents for frequency, amplitude and tension are integers, fully justified by the physics behind the phenomenon of damping. [less ▲]

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See detailPower line dynamic rating: forecasting potential period of low wind speed is crucial
Nguyen, Huu-Minh ULg; Doutreloup, Sébastien; Erpicum, Michel ULg et al

Conference (2012, September)

The replacement and building of new electrical power lines (50 000 km in Europe) can’t cope with the growth of RES development in EU for the ten upcoming years. New solutions have to be found to manage ... [more ▼]

The replacement and building of new electrical power lines (50 000 km in Europe) can’t cope with the growth of RES development in EU for the ten upcoming years. New solutions have to be found to manage such power transmission needs. Dynamic Line Rating (DLR) systems are part of the global solution. They allow to increase the power line capacity by an average 20% over the static rating (which is defined as the maximum current-carrying capacity as designed). The ampacity or thermal rating, is calculated thanks to (i) sensors installed directly on the power line conductors, like Ampacimon, (ii) weather data, and (iii) standard thermal models (IEEE, CIGRE). However, in order to be fully effective and to allow an efficient use of assets, ampacity calculation in real-time is not enough; it has to be forecasted as well. Beyond 6h-forecast, weather forecasts are necessary to compute the line ampacity up to two days ahead, as needed by network operation. As wind convection has a major impact on conductor cooling, even low wind speeds (2m/s up to 5m/s) allow a huge ampacity increase (the actual rating can be doubled). Therefore, low wind speed forecast up to 2-days ahead finds a major application in dynamic rating of overhead transmission and distribution lines. [less ▲]

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See detailPower lines real time monitoring
Lilien, Jean-Louis ULg; Guerard, Suzanne ULg; Godard, Bertrand ULg et al

in Zamrik, Sam Y. (Ed.) Proceedings of the 11th ICPVT conference (2006, July)

How to access real time data of ampacity of power lines.

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See detailThe Power of Deconvolution for Study of QSO Host Galaxies
Letawe, Géraldine ULg; Letawe, Yannick; Magain, Pierre ULg

in Proceedings of the International Astronomical Union, IAU Symposium (2010, May 01), Vol 267

The major challenge in studying QSO host galaxies is to remove the QSO contribution, which often outshines the whole system. Our group has acquired the technical ability to handle such data, for images ... [more ▼]

The major challenge in studying QSO host galaxies is to remove the QSO contribution, which often outshines the whole system. Our group has acquired the technical ability to handle such data, for images and slit spectroscopy, as well as integral field spectroscopy. We review here the major techniques developed by our team, and their latest applications. We are open for collaboration with other teams to spread the use of these powerful techniques. [less ▲]

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See detailThe power of hybrid acceleration
Boigelot, Bernard ULg; Herbreteau, Frédéric

in Lecture Notes in Computer Science (2006), 4144

This paper addresses the problem of computing symbolically the set of reachable configurations of a linear hybrid automaton. A solution proposed in earlier work consists in exploring the reachable ... [more ▼]

This paper addresses the problem of computing symbolically the set of reachable configurations of a linear hybrid automaton. A solution proposed in earlier work consists in exploring the reachable configurations using an acceleration operator for computing the iterated effect of selected control cycles. Unfortunately, this method imposes a periodicity requirement on the data transformations labeling these cycles, that is not always satisfied in practice. This happens in particular with the important subclass of timed automata, even though it is known that the paths of such automata have a periodic behavior. The goal of this paper is to broaden substantially the applicability of hybrid acceleration. This is done by introducing powerful reduction rules, aimed at translating hybrid data transformations into equivalent ones that satisfy the periodicity criterion. In particular, we show that these rules always succeed in the case of timed automata. This makes it possible to compute an exact symbolic representation of the set of reachable configurations of a linear hybrid automaton, with a guarantee of termination over the subclass of timed automata. Compared to other known solutions to this problem, our method is simpler, and applicable to a much larger class of systems. [less ▲]

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See detailThe Power of QDDs
Boigelot, Bernard ULg; Godefroid, Patrice; Willems, Bernard et al

in Lecture Notes in Computer Science (1997), 1302

Queue-content Decision Diagrams (QDDs) are finite-automaton based data structures for representing (possibly infinite) sets of contents of a finite collection of unbounded FIFO queues. Their intended use ... [more ▼]

Queue-content Decision Diagrams (QDDs) are finite-automaton based data structures for representing (possibly infinite) sets of contents of a finite collection of unbounded FIFO queues. Their intended use is to serve as a symbolic representation of the possible queue contents that can occur in the state space of a protocol modeled by finite-state machines communicating through unbounded queues. This is done with the help of a loop-first search, a state-space exploration technique that attempts whenever possible to compute symbolically the effect of repeatedly executing a loop any number of times, making it possible to analyze protocols with infinite state spaces though without the guarantee of termination. This paper first solves a key problem concerning the use of QDDs in this context: it precisely characterizes when, and shows how, the operations required by a loop-first search can be applied to QDDs. Then, it addresses the problem of exploiting QDDs and loop-first searches to broaden the range of properties that can be checked from simple state reachability to temporal logic. Finally, a sufficient criterion for the termination of a loop-first search using QDDs is given. [less ▲]

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See detailThe power of video to trigger innovation: rice processing in central Benin
Zossou, Enangnon ULg; Van Mele, Paul; Vodouhe, Davo Simplice et al

in INTERNATIONAL JOURNAL OF AGRICULTURAL SUSTAINABILITY (2009), 7(2), 119-129

Understanding how to stimulate innovation among farmers and processors is crucial for attaining sustainable agriculture. To explore how farmer-to-farmer learning videos and training workshops changed ... [more ▼]

Understanding how to stimulate innovation among farmers and processors is crucial for attaining sustainable agriculture. To explore how farmer-to-farmer learning videos and training workshops changed women’s rice processing practices, we interviewed 200 women and 17 women’s groups in 20 villages in central Benin, including four villages which had received no intervention at all. Video on improved rice parboiling (a process whereby paddy is pre-cooked by steam without touching the water) had reached three times more women (74%) than hands-on training workshops organized by local NGOs and contributed to more equitable knowledge sharing within communities. In the villages where the NGOs had shown the video, 24% of the women started to use the improved parboiler equipment individually and 56% collectively within their group, compared to none in the control villages. About 92% of the women who attended both video and workshops developed creative solutions based on the idea of pre-cooking paddy with steam, compared to 72% for those who learned only through video. Fewer women innovated after learning through workshops only (19%) and after being informed by their peers (15%). Video watching also made women pay attention to reducing the loss of steam and to use local resources innovatively to conserve energy. More than 90% of the women who watched the video improved the quality of their parboiled rice, for example, by removing dirt, washing rice several times and drying rice on tarpaulins. Workshops stimulated innovations less than video did. Farmer-to-farmer video has great potential to enhance sustainable agriculture by encouraging local innovations. [less ▲]

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See detailPower Point - support des exposés théoriques du cours de droit administratif
Durviaux, Ann-Lawrence ULg

Learning material (2010)

L'intégralité des exposés théoriques du cours sous forme de Power Point

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See detailPOWER PROCESSING UNIT ACTIVITIES AT THALES ALENIA SPACE BELGIUM
Bourguignon, Eric; Fraselle, Stéphane; Scalais, Thierry et al

in Proceedings of Space propulsion Conference 2014 (2014)

Since 1996, Thales Alenia Space Belgium (ETCA) designs, develops and produces Power Processing Unit (PPU) to supply Hall Effect Thrusters: SPT-100 from Fakel and PPS1350-G from Snecma. The first ... [more ▼]

Since 1996, Thales Alenia Space Belgium (ETCA) designs, develops and produces Power Processing Unit (PPU) to supply Hall Effect Thrusters: SPT-100 from Fakel and PPS1350-G from Snecma. The first qualification model, developed for the 50V bus Stentor program, has supplied during 8900 hours an SPT-100 thruster in a vacuum chamber simulating space environment. Qualified for the Spacebus 4000 platform, with a 100V regulated bus, the SB4000 PPU and Filter Unit EQM have cumulated 6300 hours ground operation with a PPS1350-G thruster. Twenty three PPU flight models were delivered for the Stentor, Astra-1K, Smart-1, Intelsat, Inmarsat, Eutelsat, Yahsat and DirecTV satellites. In October 2005, the Smart-1 spacecraft reached the Moon after 4958 hours of cumulated operation of the PPU with PPS1350-G thruster. Fourteen PPU’s currently in flight for North South Station Keeping on seven telecom satellites have cumulated more than 24100 hours flight operation. Following the selection of the PPS1350-G as baseline thruster for the AlphaBus platform, the Alphabus PPU was developed and two flight models were delivered for AlphaSat. Launched in July 2013, they have cumulated 350 hours operation. On the SmallGEO platform, one EPTA (Electric Propulsion Thruster Assembly) branch has to drive one out of four SPT-100 thrusters. As the PPU drives one out of two thrusters, TAS-B (ETCA) has developed and qualified an External Thruster Selection Unit (ETSU) to be associated to a PPU. Two flight sets (PPU+ETSU) were delivered for SmallGEO. In order to propose a more competitive product TAS-B (ETCA) has developed the new generation of PPU, called PPU Mk2, dedicated to Hall Effect Thrusters up to 2.5kW. The qualification phase is ending with the Qualification Test Review Board successfully hold in April 2014 and the final Qualification Review planned in June 2014. Twelve PPU Mk2 flight models are already ordered by two customers. In response to the market demand to use Electrical Propulsion for Orbit Raising, TAS-B (ETCA) has started the development of the PPU Mk3 dedicated to 5kW Hall Effect Thrusters. This paper presents an overview of the Power Processing Unit activities at TAS-B (ETCA), including flight heritage, PPU Mk2 qualification and the development of PPU Mk3. [less ▲]

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See detailPower system observability and related functions : derivation of appropriate strategies and algorithms
Van Cutsem, Thierry ULg

in International Journal of Electrical Power & Energy Systems (1985), 7

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See detailPower system security assessment: a position paper
Marceau, R.J.; Endrenyi, J.; Allan, R. et al

in Electra (1997), 175

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See detailPower System Simulation Challenges
Aristidou, Petros ULg; Plumier, Frédéric ULg; Van Cutsem, Thierry ULg et al

Scientific conference (2013, March 05)

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See detailPower system transient stability preventive and emergency control
Ruiz-Vega, Daniel; Wehenkel, Louis ULg; Ernst, Damien ULg et al

in Savulescu, Savu (Ed.) Real-Time Stability in Power Systems 2nd Edition (2014)

A general approach to real-time transient stability control is described, yielding various complementary techniques: pure preventive, open loop emergency, and closed loop emergency controls. Recent ... [more ▼]

A general approach to real-time transient stability control is described, yielding various complementary techniques: pure preventive, open loop emergency, and closed loop emergency controls. Recent progress in terms of a global transient stability constrained optimal power flow are presented, yielding in a scalable nonlinear programming formulation which allows to take near-optimal decisions for preventive control with a computing budget corresponding only to a few runs of standard optimal power flow and time domain simulations. These complementary techniques meet the stringent conditions imposed by the real-life applications. [less ▲]

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See detailPower systems stability control: Reinforcement learning framework
Ernst, Damien ULg; Glavic, Mevludin; Wehenkel, Louis ULg

in IEEE Transactions on Power Systems (2004), 19(1), 427-435

In this paper, we explore how a computational approach to learning from interactions, called reinforcement learning (RL), can be applied to control power systems. We describe some challenges in power ... [more ▼]

In this paper, we explore how a computational approach to learning from interactions, called reinforcement learning (RL), can be applied to control power systems. We describe some challenges in power system control and discuss how some of those challenges could be met by using these RL methods. The difficulties associated with their application to control power systems are described and discussed as well as strategies that can be adopted to overcome them. Two reinforcement learning modes are considered: the online mode in which the interaction occurs with the real power system and the offline mode in which the interaction occurs with a simulation model of the real power system. We present two case studies made on a four-machine power system model. The first one concerns the design by means of RL algorithms used in offline mode of a dynamic brake controller. The second concerns RL methods used in online mode when applied to control a thyristor controlled series capacitor (TCSC) aimed to damp power system oscillations. [less ▲]

Detailed reference viewed: 59 (7 ULg)