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See detailOn the hydrogen maser oscillation threshold
Mandache, Mandache; Nizet, Jean; Léonard, Daniel et al

in Applied Physics B : Lasers & Optics (2012), 107

Detailed reference viewed: 25 (3 ULg)
See detailOn the Identication of Symmetric N-qubit Maximally Entangled States
Baguette, Dorian ULg; Bastin, Thierry ULg; Martin, John ULg

Poster (2014, March 11)

Maximally entangled states can serve as a useful resource in many different contexts. It is therefore important to identify those states. Here we are interested in the identification of maximally ... [more ▼]

Maximally entangled states can serve as a useful resource in many different contexts. It is therefore important to identify those states. Here we are interested in the identification of maximally entangled states in the symmetric subspace of an N-qubit system. By maximally entangled states, we refer to symmetric states characterized by a one qubit reduced density matrix proportional to the identity. These states maximise various entanglement measures [1] such as von Neumann and Meyer-Wallach entropy and are unique up to LU in their SLOCC class [2]. We identify and characterize all maximally entangled symmetric states up to 4 qubits. We provide general conditions for a symmetric state with an arbitrary number of qubits to be maximally entangled and identify families of SLOCC classes which do not contain any maximally entangled states. [1] F. Verstraete, J. Dehaene, B. De Moor, Phys. Rev. A 68, 012103 (2003). [2] G. Gour, N. Wallach, N. J. Phys. 13, 073013 (2011) [less ▲]

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See detailOn the Impact of Clustering on Measurement Reduction
Saucez, Damien; Donnet, Benoît ULg; Bonaventure, Olivier

in 8th International IFIP-TC 6 Networking Conference (2009, May)

Measuring a path performance according to one or several metrics, such as delay or bandwidth, is becoming more and more pop- ular for applications. However, constantly probing the network is not suitable ... [more ▼]

Measuring a path performance according to one or several metrics, such as delay or bandwidth, is becoming more and more pop- ular for applications. However, constantly probing the network is not suitable. To make measurements more scalable, the notion of clustering has emerged. In this paper, we demonstrate that clustering can limit the measurement overhead in such a context without loosing too much accuracy. We first explain that measurement reduction can be observed when vantage points collaborate and use clustering to estimate path performance. We then show, with real traces, how effective is the overhead reduction and what is the impact in term of measurement accuracy. [less ▲]

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See detailOn the Impact of Electron Spectroscopies (versus Optical Techniques) to Study Organized Organic Layers and Their Interfaces
Magnée, R.; Mekhalif, Z.; Doneux, C. et al

Conference (1997, September 08)

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See detailOn the Impact of Electron Spectroscopies (Versus Optical Techniques) to Study Organized Organic Layers and Their Interfaces
Magnée, Raphael; Mekhalif, Zineb; Doneux, Catherine et al

in Journal of Electron Spectroscopy & Related Phenomena (1998), 88-91

When preparing and characterizing ordered organic layers, knowledge of the structure of the ultra-thin fihns is often missing or difficult to gather. For different self-assembled layers of the thiol and ... [more ▼]

When preparing and characterizing ordered organic layers, knowledge of the structure of the ultra-thin fihns is often missing or difficult to gather. For different self-assembled layers of the thiol and carboxylic acid families, we show that this valuable type of information is obtainable with X-ray photoelectron spectroscopy (XPS) and high-resolution electron energyqoss spectroscopy (HREELS). Indeed, information on the film order and superficial composition is available through analysis of the core-level peak positions and widths (in XPS), and through study of the elastic peak width and angular distribution and analysis of the material excitation function (in HREELS). However, [or some insight into the crystallinity of the layer and intermolecular interactions, infrared spectroscopy in the grazing-angle absorption--reflection mode (IRASI appears to be complementary [less ▲]

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See detailOn the impact of entropy estimation on transcriptional regulatory network inference based on mutual information
Olsen, Catharina; Meyer, Patrick ULg; Bontempi, Gianluca

in EURASIP Journal on Bioinformatics & Systems Biology (2009), 2009(1), 308959

Detailed reference viewed: 14 (0 ULg)
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See detailOn the impact of ionospheric variability and disturbances on GNSS-based positioning applications
Stankov, Stanimir; Wautelet, Gilles ULg; Lejeune, Sandrine et al

in Geophysical Research Abstracts (2011, April), 13(ABS. No EGU2011-12067),

Detailed reference viewed: 32 (4 ULg)
See detailOn the impact of labor market matching on regional disparities
Tharakan, Joseph ULg

Conference (2002, March)

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See detailOn the impact of labor market matching on regional disparities
Tharakan, Joseph ULg

Scientific conference (2003, February)

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See detailOn the impact of labor market matching on regional disparities
Tharakan, Joseph ULg

Scientific conference (2003, July)

Detailed reference viewed: 6 (0 ULg)
See detailOn the impact of labor market matching on regional disparities
Tharakan, Joseph ULg

Scientific conference (2004, May)

Detailed reference viewed: 6 (0 ULg)
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See detailOn the impact of labor market matching on regional disparities
Tharakan, Joseph ULg; Tropeano, Jean-Philippe

in Journal of Regional Science (2009), 49(1), 57-80

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See detailOn the Impact of Layer-2 on Node Degree Distribution
Mérindol, Pascal; Donnet, Benoît ULg; Bonaventure, Olivier et al

in 10th annual conference on Internet measurement (2010, November)

The Internet topology data collected through traceroute exploration has been extensively studied in the past. In particular, a remarkable property of the Internet, the power-law shape of node degree ... [more ▼]

The Internet topology data collected through traceroute exploration has been extensively studied in the past. In particular, a remarkable property of the Internet, the power-law shape of node degree distribution, drew the attention of the research community. Several studies have since questioned this property. In this paper, based on a large dataset collected using mrinfo, we show that the node degree distribution is strongly impacted by the presence of layer-2 (L2) networks, such as switches. L2 devices interconnect a large number of routers, themselves being also involved in multiple L2 interconnec- tions. Such a situation induces nodes with very high degree when analyzing the layer-3 (L3) graph with traceroute probing. Considering the physical design of a network, our analysis provides a lower bound on the bias generated by using only an L3 view. We also provide a model that can be a first step towards L2 aware topology generation. [less ▲]

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See detailOn the implementation of a sensitivity analysis in a flexible multibody dynamics environment
Bruls, Olivier ULg; Duysinx, Pierre ULg; Eberhard, Peter

Conference (2006, June)

The dynamic performance of complex mechanisms, such as machine tools, manipulators, vehicles, engines or foldable structures, can be strongly affected by flexible phenomena. Therefore, the deformation ... [more ▼]

The dynamic performance of complex mechanisms, such as machine tools, manipulators, vehicles, engines or foldable structures, can be strongly affected by flexible phenomena. Therefore, the deformation effects should be considered as soon as possible in the design procedure, which motivates the development of automatic optimization techniques for flexible multibody systems. Advanced software tools are able to simulate the dynamic behaviour of such systems, but they typically involve extensive numerical treatments. Hence, gradient-based optimization methods are of special interest since they require a quite low number of simulations, but an important problem is to obtain the sensitivities of the objective function with respect to the design parameters. Since finite difference approaches lack robustness and computational efficiency, we propose to investigate analytical or semi-analytical sensitivity analysis. Several difficulties are inherent to the simulation of flexible mechanisms. A consistent geometric formulation is necessary to describe large amplitude motion as well as possible large deformations. Here, according to the nonlinear finite element formulation, the motion is parameterized using absolute nodal coordinates, and an updated Lagrangian point of view is adopted for the rotation parameters. The joints and the rigid-body conditions are represented by algebraic constraints between the nodal coordinates, leading to differential algebraic equations of motion (DAEs). Finally, the computation of the trajectories requires a reliable simulation algorithm for nonlinear DAEs. A strong advantage of the finite element method comes from its very systematic implementation, which facilitates the development of a semi-analytical sensitivity analysis. In this work, sensitivity analysis is performed for beam elements, rigid bodies and ideal joints. The global sensitivity is then obtained by numerical assembly of the elementary contributions and by integration in the time domain. Thus, a single but extended simulation is sufficient to compute the sensitivities with respect to all parameters. In order to illustrate the method and to demonstrate its efficiency, we consider the optimal design of a car engine, where the flexibility of the connecting rods between the crankshaft and the pistons is taken into account. The objective is to find a feasible mechanical design which minimizes the level of vibrations. [less ▲]

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See detailOn the implementation of morphological operations
Van Droogenbroeck, Marc ULg

in Serra, Jean; Soille, Pierre (Eds.) Mathematical morphology and its applications to image processing (1994)

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See detailOn the importance of an M2 depopulating channel for a KrII metastable state
Biémont, Emile ULg; Derkatch, A.; Lundin, P. et al

in Physical Review Letters (2004), 93(6),

An experimental investigation of the radiative lifetime of the metastable 4s(2)4p(4)(P-3)4d D-4(7/2) level in Kr II shows an unusual situation regarding the importance of an M2 depopulation channel. While ... [more ▼]

An experimental investigation of the radiative lifetime of the metastable 4s(2)4p(4)(P-3)4d D-4(7/2) level in Kr II shows an unusual situation regarding the importance of an M2 depopulation channel. While the first order M1 and E2 channels are expected to contribute in a dominant way to the decay, the experimental result, obtained using a laser probing technique on a stored ion beam, tau=0.57+/-0.03 s, is far too short to be due to these channels according to our relativistic multiconfiguration Dirac-Fock calculation. Only if second order contributions to the decay branches (including essentially the M2 contribution) are taken into account in the calculations could the unexpected short lifetime be explained. [less ▲]

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See detailOn the Importance of Being (More) Attentive. Another Look at Descartes' Practice of Meditation.
Dubouclez, Olivier ULg

Conference (2014, October 11)

At the beginning of Meditation IV the meditator triumphantly announces that he has “now no difficulty in turning away (convertam) from imaginable things and toward things which are objects of the ... [more ▼]

At the beginning of Meditation IV the meditator triumphantly announces that he has “now no difficulty in turning away (convertam) from imaginable things and toward things which are objects of the intellect alone” (AT, VII, 53). Meditation VI thereafter confirms that pure intellection, as opposed to imagination, consists only in turning towards oneself (convertat) and demands no “peculiar effort of the mind” (73). However efforts of attention are required throughout the Meditations and Meditations IV, V and VI are no exceptions in this respect. Descartes’ Second Set of Replies (156-159) confirms that attention is needed as a mental support for metaphysical analysis in order to embrace different ideas and connect different parts of a demonstration. A thorough examination of the Meditations shows something even more interesting: attention is conceived by Descartes as a varying force that can be diminished or relaxed but also, and most importantly, increased as comparative forms like “attentius” (19; 55; 66; 71) or “diligentius” (32; 35; 45) suggest. For sure, it is an original aspect of Cartesian meditative exercise: we are not only invited to maintain our attention but also to make it more intense at a certain point. Such an increase is crucial for the development of the dream argument (55) and also for the achievement of both proofs of the existence of God (45; 66). But is it not a kind of deus ex machina that the meditator puts forward in order to overcome otherwise unsolvable difficulties? A posterior work, The Passions of the Soul, can help us understand such a strategy. In article 72, Descartes distinguishes between two kinds of attention; the first one stems from wonder and is “at its full strength from the start” (XI, 382); it is contrasted with a second type “which, being weak at first and growing only gradually, can be easily diverted” (Ibid.) Further on Descartes says that passion is useful in “strengthening thoughts… and causing them to endure into the soul” (383) but that “the application of our understanding” has the same effect when “our will fixes [it] in a particular attention or reflection” (384). This last case applies to the Meditations: the meditator who is constantly exposed to misleading influences would be easily “diverted” and even stopped if he was not pushed by his own will to go further in his metaphysical inquiry. “Peaks” of attention occurring in the Meditations are caused by volitions originating in the meditator’s resolution to attain truth and certainty and, as we shall see, they are used against three types of harmful influence: sensitive in Meditation I, imaginative in Meditation II and III, and intellectual in Meditation IV and V where old philosophical habits stand in the way of Cartesian theology. [less ▲]

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