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See detailGlobal morphology of substorm growth phases observed by the IMAGE-SI12 imager
Coumans, Valérie ULg; Blockx, Caroline ULg; Gérard, Jean-Claude ULg et al

in Journal of Geophysical Research (2007), 112(A11),

We present case studies and a statistical summary of optical observations of proton precipitation made during substorm growth phases. Our analysis is based on observations of the Doppler-shifted Lyman ... [more ▼]

We present case studies and a statistical summary of optical observations of proton precipitation made during substorm growth phases. Our analysis is based on observations of the Doppler-shifted Lyman-alpha auroral emission obtained with the SI12 Spectrographic Imager on board the IMAGE satellite. These images are used to determine the morphology and dynamics of the auroral oval and of the polar cap boundary on a global scale, as well as the total open magnetic flux and its time evolution. We also investigate the relationship with the solar wind and the interplanetary magnetic field ( IMF) characteristics measured by the ACE satellite and with the magnetic elevation angle measured by GOES-8. The statistical study shows that the sector of maximum proton precipitation during the growth phase is on average centered around 2200 MLT and rapidly shifts in local time by about 1.2 h toward midnight at the time of the onset. The open magnetic flux increases by 33% on average during the growth phase. The mean value of the open flux immediately before the substorm onset is about 0.66 GWb for substorms triggered by a northward turning of B-z and 0.74 GWb for nontriggered substorms. The averaged open flux at the substorm onset is smallest when the substorm is triggered by a sudden reversal of B-z, suggesting that the accumulation of energy by the magnetosphere is perturbed by changes in B-z. The open magnetic flux continues to increase during the 20 min following the onset, for a large number of events. The rate of equatorward displacement of the auroral oval boundaries during growth phase is typically similar to 3 deg/h. It is statistically correlated (r=0.40) with the magnitude of the Bz component of the IMF measured by the ACE satellite. It is also correlated, with higher coefficient (r=0.54), with functions describing the efficiency of solar wind energy transfer involving the transverse electric field carried by the solar wind. The equatorward motion may be global, restricted to local time sectors or a combination of both. At no nightside local time sector does the motion of the equatorial boundary appear more pronounced than at others, but the maximum displacement of the polar boundary is statistically located around midnight MLT. [less ▲]

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See detailGlobal morphology of substorm growth phases observed by the IMAGE-SI12 imager
Blockx, Caroline ULg; Gérard, Jean-Claude ULg; Coumans, Valérie ULg et al

Poster (2007)

Growth phases are observed to start from less than 30 minutes to over an hour before the substorm onset. The sector of maximum proton precipitation during the growth phase is generally located around 2200 ... [more ▼]

Growth phases are observed to start from less than 30 minutes to over an hour before the substorm onset. The sector of maximum proton precipitation during the growth phase is generally located around 2200 MLT. It rapidly moves in local time by about 1.2 hour toward midnight at the time of the onset. The open magnetic flux increases by as much as a 33% during the growth phase. The mean value of the open flux at the end of the growth phase, immediately preceding the substorm, onset is about 0.74. GWb for substorms triggered by external (solar wind) factors and 0.67 GWb for non-triggered substorms. The open magnetic flux generally drops following the onset of triggered substorms but continues to increase for non-triggered events. We interpret this behavior as an indication that the rate of opening of closed field lines on the dayside can exceed that of the nightside reconnection after the onset in non-triggered substorms. By contrast, flux closure is more efficient while the flux opening rate drops in the case of externally triggered onset, so that the closure rate exceeds that of field line opening on the dayside. The rate of equatorward displacement is typically ~ 3 deg/hour. It is statistically correlated with the magnitude of the southward Bz component of the IMF measured by the ACE satellite. It is also correlated with transfer functions describing the efficiency of solar wind energy transfer which involve the transverse electric field carried by the solar wind. The equatorward motion may be global, restricted to local time sectors or a combination of both. No nightside local time sector appears favored where the motion of the equatorial boundary would be more pronounced. The maximum displacement of the polar boundary is statistically located around midnight MLT. [less ▲]

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See detailGlobal Navigation Satellite Systems : A new tool in atmosphere sciences
Warnant, René ULg; Jodogne, Jean-Claude; Delobbe, Laurent et al

in Arijs, E.; Ducarme, B. (Eds.) Proceedings of the Earth Science Day : “Geodesy and Geophysics for the third Millenium in Belgium” (2005)

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See detailGlobal observations of proton and electron auroras in a substorm
Mende, S. B.; Frey, H. U.; Lampton, M. et al

in Geophysical Research Letters (2001), 28

This is the first report of a substorm observed by the IMAGE FUV instruments permitting global observations of electron and proton produced auroras. On the 28th of June 2000 at 1956 UT in the pre-substorm ... [more ▼]

This is the first report of a substorm observed by the IMAGE FUV instruments permitting global observations of electron and proton produced auroras. On the 28th of June 2000 at 1956 UT in the pre-substorm phase at early evening local time the proton aurora was equatorward of the electron precipitation and near midnight they were collocated. There was bright electron and proton aurora in the post midday afternoon side. The sudden brightening of the aurora at substorm onset near midnight is seen in the electrons only although there are protons present at this location. During the expansive phase both the electrons and protons expand poleward. The electron aurora forms a bright surge at the poleward boundary while the protons just show diffuse spreading. The peak intensity of the protons did not change substantially during the entire event. The proton aurora is brighter on the dusk while the electron aurora on the dawn side. As the electron surge expands poleward it leaves the protons behind. The electrons form a discrete auroral feature near the aurora-polar cap boundary, which is devoid of substantial energetic (>1 keV) proton precipitation. The presence of precipitating protons at the point where the initial brightening is seen shows that substorms are initiated on closed field lines. [less ▲]

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See detailA global overview of performance evaluation
Mouchamps, Hugues ULg

Conference (2011, March 04)

Performance evaluation presents two specific difficulties for social enterprises. At the one hand, it is complex to define what performance is, to measure the factors impacting performance through ... [more ▼]

Performance evaluation presents two specific difficulties for social enterprises. At the one hand, it is complex to define what performance is, to measure the factors impacting performance through indicators, and to sum up the scores of all the indicators. At the other hand, performance evaluation should vary with the purpose of the evaluation and the type of organization. Thus the characteristics of an ideal performance evaluation tool for social enterprises should both reflect this complexity and be contingent. [less ▲]

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See detailGlobal overview of the educational system in the French speaking Community of Belgium
Schillings, Patricia ULg; Gabelica, C.

E-print/Working paper (2007)

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See detailGlobal population structure of the stable fly (Stomoxys calcitrans) inferred by mitochondrial and nuclear sequence data
Dsouli-Aymes, N.; Michaux, Johan ULg; De Stordeur, E. et al

in Infection, Genetics and Evolution (2011), 11(2), 334-342

Stomoxys calcitrans (Diptera: Muscidae: Stomoxyini), a synanthropic fly with a worldwide distribution, is recognized to have an important medical and veterinary impact. We conducted a phylogeographic ... [more ▼]

Stomoxys calcitrans (Diptera: Muscidae: Stomoxyini), a synanthropic fly with a worldwide distribution, is recognized to have an important medical and veterinary impact. We conducted a phylogeographic analysis based on several populations from five major zoogeographic regions of the world in order to analyse population genetic structure of S. calcitrans and to trace its global dispersion. Results from mitochondrial (COI, Cyt-b and ND1-16S) and nuclear (ITS2) DNA show a substantial differentiation of Oriental populations (first lineage) from the Afrotropical, Palearctic, Nearctic, Neotropical and Oceanian populations (second lineage). The divergence time analyses suggest the separation between the two lineages approximately in mid-Pleistocene. Oriental populations are isolated and would not have participated in the colonization of other regions, unlike the Afrotropical one which seems to be the source of S. calcitrans dispersion towards other regions. Demographic analyses indicate that Oriental, Afrotropical and Palearctic regions have undergone a population expansion during late Pleistocene-early Holocene. The expansion time of this cosmopolitan species could have been influenced by continental human expansions and by animal domestication. © 2010 Elsevier B.V. [less ▲]

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See detailGlobal Power after the post-Cold War: the case of Chinese Power
Wintgens, Sophie ULg

in Revista Brasileira de Politica Internacional (in press)

The pre-eminence of the realistic conception has long locked the field of study of the power in International Relations, which is nowadays highly questioned. The analysis of some “new powers” emergence is ... [more ▼]

The pre-eminence of the realistic conception has long locked the field of study of the power in International Relations, which is nowadays highly questioned. The analysis of some “new powers” emergence is as such a tremendous learning experience. In order to go beyond the classical antagonism between the institutional perspectives (cooperation) and the realistic ones (rivalry), this paper deals with the power in an alternative way, from a heterodox approach of hegemony, which allows us to make out the phenomena of insidious and not felt so domination. Following the example of China, committed to building a status of world power, sustained by a self-legitimizing discourse abounding with Third-World overtones (anti-hegemonism, multipolarization of the world, South-South cooperation, etc.), the increase in its global influence does not only depend on the availability of its – tangible and intangible – resources, nor on its ability to mobilize them adequately (smart power). China also values the image that it has of itself (self-perception), the image that it tends to convey on the international stage (representation), as well as the perception of its status by the other actors of the international system (external recognition). The power of China is measured through its capacity to “assert itself as a reference” for its emerging peers, or even for Western powers. [less ▲]

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See detailGlobal power grids for harnessing world renewable energy
Chatzivasileiadis, Spyros; Ernst, Damien ULg; Andersson, Göran

in Jones, Lawrence (Ed.) Renewable Energy Integration: Practical Management of Variability, Uncertainty and Flexibility in Power Grids (2014)

The Global Grid advocates the connection of all regional power systems into one electricity transmission system spanning the whole globe. Power systems are currently forming larger and larger ... [more ▼]

The Global Grid advocates the connection of all regional power systems into one electricity transmission system spanning the whole globe. Power systems are currently forming larger and larger interconnections. Environmental awareness and increased electricity consumption leads more investments towards renewable energy sources, abundant in remote locations (off-shore or in deserts). The Global Grid will facilitate the transmission of this “green” electricity to load centers, serving as backbone. This chapter elaborates on the concept presenting four stages that could gradually lead to the development of a globally interconnected power network. Quantitative analyses are carried out for all stages, demonstrating that a Global Grid is both technically feasible and economically competitive. Real price data from Europe and the USA are used to identify the potential of intercontinental electricity trade, showing that substantial profits can be generated through such interconnections. [less ▲]

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See detailGlobal prevalence and skeletal implications of vitamin D inadequacy
Reginster, Jean-Yves ULg; Richy, Florent; Rabenda, Véronique ULg et al

in Annals of the Rheumatic Diseases (2005, June), 64(Suppl.III), 362

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See detailA Global Procedure for the Measurement of Selected POPs in Food
PIRARD, Catherine ULg; Focant, Jean-François ULg

Scientific conference (2007, June)

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See detailA Global Procedure for the Measurement of Selected POPs in Food
Focant, Jean-François ULg; PIRARD, Catherine ULg

Scientific conference (2007, June)

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See detailGlobal Sensitivity Analysis applied to Total Energy Use in Buildings
Ruiz Flores, Roberto ULg; Bertagnolio, Stéphane ULg; Lemort, Vincent ULg

in Proceedings of the 2nd International High Performance Buildings Conference (2012, July 16)

The work presented in this paper has been carried out in the frame of the IEA-ECBCS Annex 53 project: “Total Energy Use in Buildings: Analysis and evaluation methods”. The aim of this work is to present a ... [more ▼]

The work presented in this paper has been carried out in the frame of the IEA-ECBCS Annex 53 project: “Total Energy Use in Buildings: Analysis and evaluation methods”. The aim of this work is to present a methodology to identify the most influential parameters affecting the final energy consumption in office buildings. In order to represent buildings and HVAC systems, a representative typology was defined, modeled and simulated and subsequently a global sensitivity analysis (variance-based method) was performed. This paper provides useful information to future works related to design building decisions, building calibration, energy management strategy, etc. helping to detect and rank those factors which need to be better measured and/or estimated, in order to improve building energy efficiency. [less ▲]

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See detailGlobal Social Economy: Historical Context and Current Progress
Defourny, Jacques ULg; Develtere, Patrick; Zhao, Li

in Journal of Comparative Economic and Social Systems = Jingji Shehui Tizhi Bijiao (2011), 153(1), 146-157

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See detailGlobal stabilization of feedforward systems with exponentially unstable Jacobian linearization
Grognard, F.; Sepulchre, Rodolphe ULg; Bastin, G.

in Systems & Control Letters (1999), 37(2), 107-115

The global stabilization of a class of feedforward systems having an exponentially unstable Jacobian linearization is achieved by a high gain feedback saturated at a low level. The control law forces the ... [more ▼]

The global stabilization of a class of feedforward systems having an exponentially unstable Jacobian linearization is achieved by a high gain feedback saturated at a low level. The control law forces the derivatives of the state variables to small values along the closed loop trajectories. This “slow control” design is illustrated with a benchmark example and its limitations are emphasized. [less ▲]

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See detailGlobal strategy for the development of estrogenic compounds detection screening test
Collodoro, Mike ULg; Makasinga, Elu; Lemaire, Pascale ULg et al

Poster (2007, May)

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See detailGlobal structural behaviour of a building frame further to its partial destruction by column loss
Luu, Nguyen Nam Hai; Demonceau, Jean-François ULg; Jaspart, Jean-Pierre ULg

in Ofner, Robert; Beg, Darko; Fink, Josef (Eds.) et al EUROSTEEL 2008, 5th European Conference on Steel and Composite Structures (2008, September)

In 1969, a catastrophic event occurred in UK at the Ronal Point residential building where the progressive collapse of the building, initiated by a localized gas explosion, was observed. Further to this ... [more ▼]

In 1969, a catastrophic event occurred in UK at the Ronal Point residential building where the progressive collapse of the building, initiated by a localized gas explosion, was observed. Further to this event, some codes and standards, and in particular the British Standards, impose to the designer to ensure the structural integrity of building in order to avoid the progressive collapse of the latter further to an exceptional action. In fact, the progressive collapse of a building is the result of a change in the structural system and of the load path associated to the loss of one or more main structural members. In other words, the existing load path is suddenly modified and the loads supported by the building are reported to the foundation through an alternative load path. Accordingly, the remaining structural members are overloaded by additional loads; the latter have to be able to support these loads and to possess a sufficient ductility. In the last decade, researches on this topic were initiated at the Argenco Department of Liège University. The present paper reflects part of these activities; in particular, some investigations dedicated to the investigation of the behaviour of a frame further to a column loss are presented. In another article presented by J.F Demonceau, H.N.N. Luu and J.P Jaspart within the present conference is devoted to the investigation of the behaviour of the frame when significant membranar forces developed within the structure. In particular, in this paper, a simplified substructure which is able to simulate the behaviour of a structure further to a column loss is defined. The present paper presents the analytical methods requested to define the parameters influencing the response of the simplified substructure. [less ▲]

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See detailGlobal synchronization on the circle
Sarlette, Alain ULg; Tuna, Sezai Emre; Blondel, Vincent et al

in Proceedings of the 17th IFAC World Congress (2008, July)

The convexity arguments used in the consensus literature to prove synchronization in vector spaces can be applied to the circle only when all agents are initially located on a semicircle. Existing ... [more ▼]

The convexity arguments used in the consensus literature to prove synchronization in vector spaces can be applied to the circle only when all agents are initially located on a semicircle. Existing strategies for (almost-)global synchronization on the circle are either restricted to specific interconnection topologies or use auxiliary variables. The present paper first illustrates this problem by showing that weighted, directed interconnection topologies can be designed to make any reasonably chosen configuration of the agents on the circle a stable equilibrium of a basic continuous-time consensus algorithm. Then it proposes a so-called “gossip algorithm”, which achieves global asymptotic synchronization on the circle with probability 1 for a large class of interconnections, without using auxiliary variables, thanks to the introduction of randomness in the system. [less ▲]

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See detailGlobal tracking and state estimation with non- smooth impacts for a mass confined to an n-dimensional half-space
Forni, Fulvio ULg; Teel, Andrew; Zaccarian, Luca

in IFAC Conference on Analysis and Design of Hybrid Systems (ADHS 12) (2012)

We formulate tracking and state-estimation problems of a translating mass moving in an n-dimensional space and impacting on a hyperplane. Due to the discontinuous trajectories arising from the nonsmooth ... [more ▼]

We formulate tracking and state-estimation problems of a translating mass moving in an n-dimensional space and impacting on a hyperplane. Due to the discontinuous trajectories arising from the nonsmooth impacts, we use hybrid systems stability analysis tools to establish that 1) a tracking control algorithm and 2) an observer algorithm guarantee global exponential stability. Then, based on a separation principle, we combine the two constructions above to design a dynamic output feedback controller ensuring asymptotic tracking. [less ▲]

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