Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailLow-rank optimization for distance matrix completion
Mishra, Bamdev ULg; Meyer, Gilles ULg; Sepulchre, Rodolphe ULg

in Proceedings of the 50th IEEE Conference on Decision and Control (2011, December)

This paper addresses the problem of low-rank distance matrix completion. This problem amounts to recover the missing entries of a distance matrix when the dimension of the data embedding space is possibly ... [more ▼]

This paper addresses the problem of low-rank distance matrix completion. This problem amounts to recover the missing entries of a distance matrix when the dimension of the data embedding space is possibly unknown but small compared to the number of considered data points. The focus is on high-dimensional problems. We recast the considered problem into an optimization problem over the set of low-rank positive semidefinite matrices and propose two efficient algorithms for low-rank distance matrix completion. In addition, we propose a strategy to determine the dimension of the embedding space. The resulting algorithms scale to high-dimensional problems and monotonically converge to a global solution of the problem. Finally, numerical experiments illustrate the good performance of the proposed algorithms on benchmarks. [less ▲]

Detailed reference viewed: 60 (11 ULg)
Full Text
Peer Reviewed
See detailLow-rank optimization on the cone of positive semidefinite matrices
Journee, Michel ULg; Bach, F.; Absil, P.-A. et al

in SIAM Journal on Optimization (2010), 20(5)

Detailed reference viewed: 178 (12 ULg)
See detailLow-rank optimization with trace norm penalty
Mishra, Bamdev ULg; Meyer, Gilles ULg; Bach, Francis et al

E-print/Working paper (2012)

The paper addresses the problem of low-rank trace norm minimization. We propose an algorithm that alternates between fixed-rank optimization and rank-one updates. The fixed-rank optimization is ... [more ▼]

The paper addresses the problem of low-rank trace norm minimization. We propose an algorithm that alternates between fixed-rank optimization and rank-one updates. The fixed-rank optimization is characterized by an efficient factorization that makes the trace norm differentiable in the search space and the computation of duality gap numerically tractable. The search space is nonlinear but is equipped with a particular Riemannian structure that leads to efficient computations. We present a second-order trust-region algorithm with a guaranteed quadratic rate of convergence. Overall, the proposed optimization scheme converges super-linearly to the global solution while still maintaining complexity that is linear in the number of rows of the matrix. To compute a set of solutions efficiently for a grid of regularization parameters we propose a predictor-corrector approach on the quotient manifold that outperforms the naive warm-restart approach. The performance of the proposed algorithm is illustrated on problems of low-rank matrix completion and multivariate linear regression. [less ▲]

Detailed reference viewed: 60 (23 ULg)
Full Text
Peer Reviewed
See detailLow-rank plus sparse decomposition for exoplanet detection in direct-imaging ADI sequences. The LLSG algorithm
Gómez González, Carlos ULg; Absil, Olivier ULg; Absil, P.-A. et al

in Astronomy and Astrophysics (2016), 589

Context. Data processing constitutes a critical component of high-contrast exoplanet imaging. Its role is almost as important as the choice of a coronagraph or a wavefront control system, and it is ... [more ▼]

Context. Data processing constitutes a critical component of high-contrast exoplanet imaging. Its role is almost as important as the choice of a coronagraph or a wavefront control system, and it is intertwined with the chosen observing strategy. Among the data processing techniques for angular differential imaging (ADI), the most recent is the family of principal component analysis (PCA) based algorithms. It is a widely used statistical tool developed during the first half of the past century. PCA serves, in this case, as a subspace projection technique for constructing a reference point spread function (PSF) that can be subtracted from the science data for boosting the detectability of potential companions present in the data. Unfortunately, when building this reference PSF from the science data itself, PCA comes with certain limitations such as the sensitivity of the lower dimensional orthogonal subspace to non-Gaussian noise. <BR /> Aims: Inspired by recent advances in machine learning algorithms such as robust PCA, we aim to propose a localized subspace projection technique that surpasses current PCA-based post-processing algorithms in terms of the detectability of companions at near real-time speed, a quality that will be useful for future direct imaging surveys. <BR /> Methods: We used randomized low-rank approximation methods recently proposed in the machine learning literature, coupled with entry-wise thresholding to decompose an ADI image sequence locally into low-rank, sparse, and Gaussian noise components (LLSG). This local three-term decomposition separates the starlight and the associated speckle noise from the planetary signal, which mostly remains in the sparse term. We tested the performance of our new algorithm on a long ADI sequence obtained on β Pictoris with VLT/NACO. <BR /> Results: Compared to a standard PCA approach, LLSG decomposition reaches a higher signal-to-noise ratio and has an overall better performance in the receiver operating characteristic space. This three-term decomposition brings a detectability boost compared to the full-frame standard PCA approach, especially in the small inner working angle region where complex speckle noise prevents PCA from discerning true companions from noise. [less ▲]

Detailed reference viewed: 43 (16 ULg)
Full Text
Peer Reviewed
See detailLow-temperature chemical vapor deposition of highly-doped n-type epitaxial Si at high growth rate
Nguyen, Ngoc Duy ULg; Loo, Roger; Caymax, Matty

Conference (2007)

We investigated the growth of in-situ n-type doped epitaxial Si layers with arsenic and phosphorus by means of low-temperature chemical vapor deposition using trisilane as Si-precursor. Indeed, in order ... [more ▼]

We investigated the growth of in-situ n-type doped epitaxial Si layers with arsenic and phosphorus by means of low-temperature chemical vapor deposition using trisilane as Si-precursor. Indeed, in order to prevent the alteration of the characteristics of the devices which are already present on the wafer, an epitaxy process at low temperature is highly desired for applications such as BiCMOS. In this work, the varying parameters are the deposition temperature, the Si-precursor mass flow and the dopant gas flow. As a result, a process for the deposition of heavily doped epilayers was demonstrated at 600 °C with high deposition rate, which is important for maintaining high throughput and low process cost. We showed that using trisilane as a Si-precursor resulted in a much more linear n-type doping behavior than using dichlorosilane. Therefore it allowed an easier process control and a wider dynamic doping range. Our process is an interesting route for the epitaxy of a low-resistance emitter layer for bipolar transistor application. [less ▲]

Detailed reference viewed: 17 (0 ULg)
Full Text
Peer Reviewed
See detailLow-temperature epitaxy of highly-doped n-type Si at high growth rate by chemical vapor deposition for bipolar transistor application
Nguyen, Ngoc Duy ULg; Loo, Roger; Caymax, Matty

in Applied Surface Science (2008), 264

We investigated the growth of in-situ n-type doped epitaxial Si layers with arsenic and phosphorus by means of low-temperature chemical vapor deposition using trisilane as Si-precursor. Indeed, in order ... [more ▼]

We investigated the growth of in-situ n-type doped epitaxial Si layers with arsenic and phosphorus by means of low-temperature chemical vapor deposition using trisilane as Si-precursor. Indeed, in order to prevent the alteration of the characteristics of the devices which are already present on the wafer, an epitaxy process at low temperature is highly desired for applications such as BiCMOS. In this work, the varying parameters are the deposition temperature, the Si-precursor mass flow and the dopant gas flow. As a result, a process for the deposition of heavily doped epilayers was demonstrated at 600 °C with high deposition rate, which is important for maintaining high throughput and low process cost. We showed that using trisilane as a Si-precursor resulted in a much more linear n-type doping behavior than using dichlorosilane. Therefore it allowed an easier process control and a wider dynamic doping range. Our process is an interesting route for the epitaxy of a low-resistance emitter layer for bipolar transistor application. [less ▲]

Detailed reference viewed: 42 (3 ULg)
Full Text
See detailLow-viscosity allophanates containing actinically curable groups
Detrembleur, Christophe ULg; Weikard, Jan; Greszta-Franz, Dorota et al

Patent (2011)

A process for preparing binders containing allophanate groups which contain, at the oxygen atom of the allophanate group that is bonded via two single bonds, organic radicals with activated groups capable ... [more ▼]

A process for preparing binders containing allophanate groups which contain, at the oxygen atom of the allophanate group that is bonded via two single bonds, organic radicals with activated groups capable of participating in a polymerization reaction with ethylenically unsaturated compounds on exposure to actinic radiation; the process includes reacting A) one or more compounds containing uretdione groups with B) one or more OH-functional compounds which contain groups capable of participating in a polymerization reaction with ethylenically unsaturated compounds on exposure to actinic radiation, and C) optionally further NCO-reactive compounds, and D) in the presence of one or more compounds containing phenoxide groups, as catalysts.; The binders can be used in preparing coatings, coating materials, coating compositions, adhesives, printing inks, casting resins, dental compounds, sizes, photoresists, stereolithography systems, resins for composite materials and sealants. [less ▲]

Detailed reference viewed: 39 (6 ULg)
Full Text
See detailLow-viscosity allophanates containing actinically curable groups
Detrembleur, Christophe ULg; Weikard, Jan; Greszta-Franz, Dorota et al

Patent (2008)

A process for preparing binders containing allophanate groups which contain, at the oxygen atom of the allophanate group that is bonded via two single bonds, organic radicals with activated groups capable ... [more ▼]

A process for preparing binders containing allophanate groups which contain, at the oxygen atom of the allophanate group that is bonded via two single bonds, organic radicals with activated groups capable of participating in a polymerization reaction with ethylenically unsaturated compounds on exposure to actinic radiation; the process includes reacting A) one or more compounds containing uretdione groups with B) one or more OH-functional compounds which contain groups capable of participating in a polymerization reaction with ethylenically unsaturated compounds on exposure to actinic radiation, and C) optionally further NCO-reactive compounds, and D) in the presence of one or more compounds containing phenoxide groups, as catalysts.; The binders can be used in preparing coatings, coating materials, coating compositions, adhesives, printing inks, casting resins, dental compounds, sizes, photoresists, stereolithography systems, resins for composite materials and sealants. [less ▲]

Detailed reference viewed: 25 (4 ULg)
Full Text
See detailLow-viscosity allophanates having actinically hardenable groups
Detrembleur, Christophe ULg; Weikard, Jan; Richter, Frank et al

Patent (2009)

Die vorliegende Erfindung betrifft niedrigviskose Umsetzungsprodukte von Polyisocyanaten, die aktivierte unter Einwirkung aktinischer Strahlung mit ethylenisch ungesättigten Verbindungen unter ... [more ▼]

Die vorliegende Erfindung betrifft niedrigviskose Umsetzungsprodukte von Polyisocyanaten, die aktivierte unter Einwirkung aktinischer Strahlung mit ethylenisch ungesättigten Verbindungen unter Polymerisation reagierende Gruppen enthalten, ein Verfahren zu ihrer Herstellung sowie deren Verwendung in Beschichtungsmitteln. [less ▲]

Detailed reference viewed: 53 (4 ULg)
Full Text
See detailLow-viscosity allophanates having actinically hardenable groups
Detrembleur, Christophe ULg

Patent (2007)

Die vorliegende Erfindung betrifft niedrigviskose Umsetzungsprodukte von Polyisocyanaten, die aktivierte unter Einwirkung aktinischer Strahlung mit ethylenisch ungesättigten Verbindungen unter ... [more ▼]

Die vorliegende Erfindung betrifft niedrigviskose Umsetzungsprodukte von Polyisocyanaten, die aktivierte unter Einwirkung aktinischer Strahlung mit ethylenisch ungesättigten Verbindungen unter Polymerisation reagierende Gruppen enthalten, ein Verfahren zu ihrer Herstellung sowie deren Verwendung in Beschichtungsmitteln. [less ▲]

Detailed reference viewed: 17 (3 ULg)
Full Text
See detailLow-viscosity allophanates having actinically hardenable groups
Weikard, Jan; Detrembleur, Christophe ULg; Grestza-Franz, Dorota et al

Patent (2006)

A radiation-curing binder containing allophanate groups is prepared by reacting at =130[deg]C compound(s) containing uretdione groups with OH-functional compounds containing groups reacting with ... [more ▼]

A radiation-curing binder containing allophanate groups is prepared by reacting at =130[deg]C compound(s) containing uretdione groups with OH-functional compounds containing groups reacting with polymerization with ethylenically unsaturated compounds on exposure to actinic radiation, optionally other NCO-reactive compounds, in the presence of a catalyst comprising at least one zinc compound to form allophanate groups by opening the uretdione ring. Independent claims are also included for: (A) a coating composition comprising the radiation-curing binder(s) containing allophanate groups, optionally polyisocyanate(s) containing free or blocked isocyanate groups, which are free from groups which react, with polymerization, with ethylenically unsaturated compounds on exposure to actinic radiation, optionally other compounds containing groups which react, with polymerization, with ethylenically unsaturated compounds on exposure to actinic radiation, and optionally contain free or blocked NCO groups, optionally one or more isocyanate-reactive compounds, initiator(s), and optionally solvents; and (B) a substrate coated with a coating obtained from the radiation-curing binder containing allophanate groups. [less ▲]

Detailed reference viewed: 61 (3 ULg)
Full Text
See detailLower Carboniferous shallow marine sequences from the Central Alborz Basin, Iran (north-eastern margin of Gondwana): sedimentology, biostratigraphy and rock– magnetic studies
Sardar Abadi, Mehrdad ULg

Doctoral thesis (2016)

The Lower Carboniferous Mobarak Formation records the development of a carbonate platform on the southern Paleo-Tethyan passive margin. This pervasive carbonate factory was deposited following the opening ... [more ▼]

The Lower Carboniferous Mobarak Formation records the development of a carbonate platform on the southern Paleo-Tethyan passive margin. This pervasive carbonate factory was deposited following the opening of the Paleo-Tethys Ocean into the Alborz Basin along the northern margin of Gondwana. The depositional facies range from the most proximal to the most distal and include coastal environments, inner ramp peritidal facies, peloidal to crinoidal shoals, storm to fair-weather influenced mid-ramps, proximal to distal shell beds and low energy outer ramps. Storms clearly played a dominant role in the distribution of skeletal and non-skeletal shoals on the carbonate ramp. Sedimentological analyses complemented with foraminiferal biostratigraphy reveal four events which are interpreted to represent the principal factors controlling carbonate platform evolution in the Alborz Basin during the Lower Carboniferous: 1) A transgression linked to global temperature rise in the Early Tournaisian (Middle Hastarain) resulted in the formation of thick-bedded argillaceous limestones. 2) the Hastarian–Ivorian boundary glaciation phase, 3) Upper Ivorian–Lower Viséan? tectonic block faulting. 4) the Viséan- Serpukhovian glaciation phase. The three foraminiferal assemblages encountered in the Tournaisian interval of the Mobarak Formation are restricted to specific periods within the Ivorian. The occurrence of specific foraminiferal taxa in Alborz is tightly governed by transgressions and migration of North Paleo–Tethyan biotic elements as response to the thermal period. We also combined proxies for ambient paleothermometry in addition to the indications for arid conditions and arid conditions and the presence of foraminiferal taxa with a North Paleo-Tethyan affinity in the Lower Carboniferous Mobarak Formation to suggest a paleo-position for the Alborz Basin at lower latitudes than approximately 45  –50  southern paleolatitude reported thus far. Magnetic susceptibility ( in ) was measured and compared with facies from the same sample. There is a clear link between  in and facies, and the average  in values are higher for distal facies than for proximal ones. The  in profile of Lower Carboniferous carbonate sequence reflects stratigraphic variations in response to relative sea level changes and detrital input. In the context of the sequence stratigraphic framework, the average  in values for lowstand and transgressive system tracts deposits are higher than for the highstand system tracts deposits. The clear link between  in and facies points to at least partly preserved primary  in signal, related to detrital inputs. In respect to the hysteresis measurements the in signal is mainly carried by low coercivity ferromagnetic minerals such as magnetite, with a mixture of relatively coarse grains (detrital fraction) and ultra-fine grains (probably formed during diagenesis). [less ▲]

Detailed reference viewed: 28 (4 ULg)
Full Text
Peer Reviewed
See detailLower airway dysfunction in athletic horses
Votion, Dominique ULg; Art, Tatiana ULg; Lekeux, Pierre ULg

in In Proceedings: Journées Vétérinaires Suisses (1996, September)

During the last decade, research in exercising horses provided growing evidence that the respiratory system may be a limiting factor for maximal performance, even in healthy animals. Therefore, any ... [more ▼]

During the last decade, research in exercising horses provided growing evidence that the respiratory system may be a limiting factor for maximal performance, even in healthy animals. Therefore, any pulmonary dysfunction, even subclinical or moderate, may significantly impair the aerobic metabolism and consequently performance of exercising horses. This paper briefly presents the main respiratory troubles of lower airway as well as the main pulmonary function tests used to diagnose these diseases. [less ▲]

Detailed reference viewed: 17 (0 ULg)
Full Text
Peer Reviewed
See detailLower airway function: response to exercise and training
Art, Tatiana ULg; Bayly, Warwick

in Hinchcliff, Kenneth W.; Kaneps, Andris J.; Geor, Raymont J. (Eds.) Equine Sports Medicine and Surgery. Basic and clinical Sciences of the Equine Athlete. 2d Edition (2014)

Detailed reference viewed: 18 (2 ULg)
Full Text
Peer Reviewed
See detailLower and Middle Devonian miospore-based stratigraphy in Libya and its relation to the megafloras and faunas
Streel, Maurice ULg; Fairon-Demaret, Muriel ULg; Gerrienne, Philippe ULg et al

in Review of Palaeobotany and Palynology (1990), 66(3), 229--242

Detailed reference viewed: 27 (9 ULg)
See detailLower Carboniferous corals from the Zonguldak Area (Black Sea, Northwestern Turkey).
Denayer, Julien ULg

in PPMB-MVP meeting abstract book (2009, December 04)

Detailed reference viewed: 37 (6 ULg)