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See detailOn the human pose recovery based on a single view
Pierard, Sébastien ULg; Van Droogenbroeck, Marc ULg

in International conference on pattern recognition applications and methods (ICPRAM) (2012, February)

Estimating the pose of the observed person is crucial for a large variety of applications including home entertainment, man-machine interaction, video surveillance, etc. Often, only a single side view is ... [more ▼]

Estimating the pose of the observed person is crucial for a large variety of applications including home entertainment, man-machine interaction, video surveillance, etc. Often, only a single side view is available, but authors claim that it is possible to derive the pose despite that humans evolve in a 3D environment. In addition, to decrease the sensitivity to color and texture, it is preferable to rely only on the silhouette to recover the pose. Under these conditions, we show that there is an intrinsic limitation: at least two poses correspond to the observed silhouette. We discuss this intrinsic limitation in details in this short paper. To our knowledge, this issue has been overlooked by authors in the past. We observe that this limitation has an impact on the way previous reported results should be interpreted, and it has clearly to be taken into account for designing new methods. [less ▲]

Detailed reference viewed: 104 (13 ULg)
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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: 21 (0 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 ▲]

Detailed reference viewed: 9 (1 ULg)
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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)

Detailed reference viewed: 2 (1 ULg)
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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 ▲]

Detailed reference viewed: 22 (0 ULg)
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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: 13 (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: 30 (4 ULg)
See detailOn the impact of labor market matching on regional disparities
Tharakan, Joseph ULg

Scientific conference (2003, July)

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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

Detailed reference viewed: 38 (15 ULg)
See detailOn the impact of labor market matching on regional disparities
Tharakan, Joseph ULg

Scientific conference (2003, February)

Detailed reference viewed: 8 (0 ULg)
See detailOn the impact of labor market matching on regional disparities
Tharakan, Joseph ULg

Conference (2002, March)

Detailed reference viewed: 10 (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 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)

Detailed reference viewed: 42 (5 ULg)