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See detailCombining numerous uncorrelated MEMS gyroscopes for accuracy improvement based on an optimal Kalman filter
Chang, Honglong; Xue, Liang; Jiang, Chengyu et al

in IEEE Transactions on Instrumentation and Measurement (2012), 61(11), 3084--3093

In this paper, an approach to improve the accuracy of microelectromechanical systems (MEMS) gyroscopes by combining numerous uncorrelated gyroscopes is presented. A Kalman filter (KF) is used to fuse the ... [more ▼]

In this paper, an approach to improve the accuracy of microelectromechanical systems (MEMS) gyroscopes by combining numerous uncorrelated gyroscopes is presented. A Kalman filter (KF) is used to fuse the output signals of several uncorrelated sensors. The relationship between the KF bandwidth and the angular rate input is quantitatively analyzed. A linear model is developed to choose suitable system parameters for a dynamic application of the concept. Simulation and experimental tests of a six-gyroscope array proved that the presented approach was effective to improve the MEMS gyroscope accuracy. The experimental results indicate that six identical gyroscopes with a noise density of 0.11°/s/$\surd$Hz and a bias instability of 62°/h can be combined to form a virtual gyroscope with a noise density of 0.03°/s/$\surd$Hz and a bias instability of 16.8°/h . The accuracy improvement is better than that of a simple averaging process of the individual sensors. [less ▲]

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See detailCombining PET images and neuropsychological test data for automatic diagnosis of Alzheimer’s disease
Segovia-Román, Fermín ULg; Bastin, Christine ULg; Salmon, Eric ULg et al

in PLoS ONE (2014), 9(2),

In recent years, several approaches to develop computer aided diagnosis (CAD) systems for dementia have been proposed. Some of these systems analyze neurological brain images by means of machine learning ... [more ▼]

In recent years, several approaches to develop computer aided diagnosis (CAD) systems for dementia have been proposed. Some of these systems analyze neurological brain images by means of machine learning algorithms in order to find the patterns that characterize the disorder, and a few combine several imaging modalities to improve the diagnostic accuracy. However, they usually do not use neuropsychological testing data in that analysis. The purpose of this work is to measure the advantages of using not only neuroimages as data source in CAD systems for dementia but also neuropsychological scores. To this aim, we compared the accuracy rates achieved by systems that use neuropsychological scores beside the imaging data in the classification step and systems that use only one of these data sources. In order to address the small sample size problem and facilitate the data combination, a dimensionality reduction step (implemented using three different algorithms) was also applied on the imaging data. After each image is summarized in a reduced set of image features, the data sources were combined and classified using three different data combination approaches and a Support Vector Machine classifier. That way, by testing different dimensionality reduction methods and several data combination approaches, we aim not only highlighting the advantages of using neuropsychological scores in the classification, but also implementing the most accurate computer system for early dementia detention. The accuracy of the CAD systems were estimated using a database with records from 46 subjects, diagnosed with MCI or AD. A peak accuracy rate of 89% was obtained. In all cases the accuracy achieved using both, neuropsychological scores and imaging data, was substantially higher than the one obtained using only the imaging data. [less ▲]

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See detailCombining problem structure and basis reduction to solve a class of hard integer programs
Louveaux, Quentin ULg; Wolsey, Laurence A.

in Mathematics of Operations Research (2002), 27(3), 470-484

We consider a hard integer programming problem that is difficult for the standard branch-and-bound approach even for small instances. A reformulation based on lattice basis reduction is known to be more ... [more ▼]

We consider a hard integer programming problem that is difficult for the standard branch-and-bound approach even for small instances. A reformulation based on lattice basis reduction is known to be more effective. However the step to compute the reduced basis, even if it is found in polynomial time, becomes a bottleneck for small to medium instances. By using the structure of the problem, we show that we can decompose the problem and obtain the basis by taking the kronecker product of two smaller bases easier to compute. Furthermore, if the two small bases are reduced, the kronecker product is also reduced up to a reordering of the vectors. Computational results show the gain from such an approach. [less ▲]

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See detailCombining proteomics and metabolite analyses to unravel cadmium stress-response in poplar leaves
Kieffer, Pol ULg; Planchon, Sébastien; Oufir, Mouhssin et al

in Journal of Proteome Research (2009), 8

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See detailCombining remote sensing imagery of both fine and coarse spatial resolution to estimate crop evapotranspiration and quantifying its influence on crop growth monitoring
Sepulcre-Canto, Guadalupe; Gellens-Meulenberghs, Françoise; Arboleda, Alirio et al

in Geophysical Research Abstracts (2010)

This study has been carried out in the framework of the GLOBAM -Global Agricultural Monitoring system by integration of earth observation and modeling techniques- project whose objective is to fill the ... [more ▼]

This study has been carried out in the framework of the GLOBAM -Global Agricultural Monitoring system by integration of earth observation and modeling techniques- project whose objective is to fill the methodological gap between the state of the art of local crop monitoring and the operational requirements of the global monitoring system programs. To achieve this goal, the research aims to develop an integrated approach using remote sensing and crop growth modeling. This paper concerns the use of MSG geostationnary satellite data for the calculation of Actual Evapotranspiration and its integration into a crop growth model. [less ▲]

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See detailCombining satellite, aerial and ground measurements to assess forest carbon stocks in Democratic Republic of Congo
Beaumont, Benoît; Bouvy, Alban; Stephenne, Nathalie et al

in Geophysical Research Abstracts, Vol. 17, EGU2015-4765-2, 2015 (2015)

Monitoring tropical forest carbon stocks changes has been a rising topic in the recent years as a result of REDD+ mechanisms negotiations. Such monitoring will be mandatory for each country willing to ... [more ▼]

Monitoring tropical forest carbon stocks changes has been a rising topic in the recent years as a result of REDD+ mechanisms negotiations. Such monitoring will be mandatory for each country willing to benefit from these financial incentives in the future. Aerial and satellite remote sensing technologies offer cost advantages in implementing large scale forest inventories. Despite the recent progress made in the use of airborne LiDAR for C stocks estimation, no widely operational and cost effective method has yet been delivered for central Africa forest monitoring. Within the Maï Ndombe region of DRC, the EO4REDD project develops a method combining satellite, aerial and ground measurements. This combination is done in three steps: [1] mapping and quantifying forest cover changes using an object-based semi-automatic change detection (deforestation and forest degradation) methodology based on very high resolution satellite imagery (RapidEye), [2] developing an allometric linear model for above ground biomass measurements based on dendrometric parameters (tree crown areas and heights) extracted from airborne stereoscopic image pairs and calibrated using ground measurements of individual trees on a data set of 18 one hectare plots and [3] relating these two products to assess carbon stocks changes at a regional scale. Given the high accuracies obtained in [1] (> 80% for deforestation and 77% for forest degradation) and the suitable, but still to be improved with a larger calibrating sample, model (R2 of 0.7) obtained in [2], EO4REDD products can be seen as a valid and replicable option for carbon stocks monitoring in tropical forests. Further improvements are planned to strengthen the cost effectiveness value/REDD+ suitability in the 2nd phase of EO4REDD. This 2nd phase will include [A] specific model developments per forest type; [B] measurements of afforestation, reforestation and natural regeneration processes and [C] study of Sentinel data series potential use. [less ▲]

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See detailCombining seismology and spectropolarimetry of hot stars
Neiner, Coralie; Briquet, Maryline ULg; Mathis, Stéphane et al

in IAU Symosium 307 (2015, January)

Asteroseismology and spectropolarimetry have allowed us to progress significantly in our understanding of the physics of hot stars over the last decade. It is now possible to combine these two techniques ... [more ▼]

Asteroseismology and spectropolarimetry have allowed us to progress significantly in our understanding of the physics of hot stars over the last decade. It is now possible to combine these two techniques to learn even more information about hot stars and constrain their models. While only a few magnetic pulsating hot stars are known as of today and have been studied with both seismology and spectropolarimetry, new opportunities - in particular Kepler2 and BRITE - are emerging and will allow us to rapidly obtain new combined results. [less ▲]

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See detailCombining shearography and interferometric fringe projection in a single device for complete control of industrial applications
Blain, Pascal ULg; Michel, Fabrice; Piron, Pierre ULg et al

in Optical Engineering : The Journal of the Society of Photo-Optical Instrumentation Engineers (2013), 52(8), 0841021-7

Non-contact optical measurement methods are essential tools in many industrial and research domains. A family of new non-contact optical measurement methods based on the polarization states splitting ... [more ▼]

Non-contact optical measurement methods are essential tools in many industrial and research domains. A family of new non-contact optical measurement methods based on the polarization states splitting technique and monochromatic light projection as a way to overcome ambient lighting for in-situ measurement has been developed. Recent works on a birefringent element, a Savart plate, allow to build a more flexible and robust interferometer. This interferometer is a multipurpose metrological device. On one hand the interferometer can be set in front of a CCD camera. This optical measurement system is called a shearography interferometer and allows to measure micro displacements between two states of the studied object under coherent lighting. On the other hand by producing and shifting multiple sinusoidal Young’s interference patterns with this interferometer, and using a CCD camera, it is possible to build a 3D structured light profilometer. [less ▲]

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See detailCombining spatial data in landslide reactivation susceptibility mapping: A likelihood ratio-based approach in W Belgium
Dewitte, Olivier ULg; Chung, Chang-Jo; Cornet, Yves ULg et al

in Geomorphology (2010)

A key issue in landslide susceptibility mapping concerns the relevance of the spatial data combination used in the prediction. Various combinations of high-resolution predictor variables and possibilities ... [more ▼]

A key issue in landslide susceptibility mapping concerns the relevance of the spatial data combination used in the prediction. Various combinations of high-resolution predictor variables and possibilities of selecting them from a larger dataset are analysed. The scarp reactivation of several landslides in a hilly region of W Belgium is investigated at the pixel scale. The usceptibility modelling uses the reactivated scarp segments as the dependent variable and 13 factors at a 2 m-resolution related to topography, hydrology, land use and lithology as potential independent variables. The modelling uses a likelihood ratio approach based on the comparison, for each independent variable, between two empirical distribution functions (EDFs), respectively for the reactivated and non-reactivated areas. It uses these EDFs as favourability values to build membership values and combine them with a fuzzy Gamma operator. Five different data combinations are tested and compared by analysing the prediction-rate curves obtained by cross-validation. The geomorphological value of the resulting susceptibility maps is also discussed. This research shows relevant results for predicting the susceptibility to scarp reactivation. We highlight the need for testing several data combinations and underline that combining uantitative criteria with expert opinion is an asset for reliable predictions. [less ▲]

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See detailCombining stochastic simulations and inverse modelling for delineation of groundwater well capture zones
Rentier, Céline; Roubens, Marc ULg; Dassargues, Alain ULg

in Iu (Ed.) Computational Methods in Engineering and Science (2003)

In hydrogeology, protection zones of a spring or a pumping well are often delimited by isochrones that are computed using calibrated groundwater flow and transport models. In heterogeneous formations, all ... [more ▼]

In hydrogeology, protection zones of a spring or a pumping well are often delimited by isochrones that are computed using calibrated groundwater flow and transport models. In heterogeneous formations, all direct and indirect data, respectively called hard and soft data, must be used in an optimal way. Approaches involving in situ pumping and tracer tests, combined with geophysical and/or other geological observations, are developed. In a deterministic framework, the calibrated model is considered as the best representation of the reality at the current investigation stage, but result uncertainty remains unquantified. Using stochastic methods, a range of equally likely isochrones can be produced allowing to quantify the influence of our knowledge of the aquifer parameters on protection zone uncertainty. Furthermore, integration of soft data in a conditioned stochastic generation process, possibly associated with an inverse modeling procedure, can reduce the resulting uncertainty. A stochastic methodology for protection zone delineation integrating hydraulic conductivity measurements (hard data), head observations and electrical resistivity data (soft data) is proposed. [less ▲]

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See detailCombining Surface Impedance Boundary Conditions with Volume Discretisation in Time-Domain Finite-Element Modeling
Gyselinck, Johan; Dular, Patrick ULg; Geuzaine, Christophe ULg et al

in Proceedings of the 14th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2010) (2010, May)

In this paper a hybrid approach for considering massive conducting regions in time-domain finite-element modeling is presented. Surface impedance boundary conditions, developed in the time domain as ... [more ▼]

In this paper a hybrid approach for considering massive conducting regions in time-domain finite-element modeling is presented. Surface impedance boundary conditions, developed in the time domain as previously proposed by the authors, are adopted so as to allow for high-frequency flux components (in a certain frequency band) without the need for very fine discretisation of the conducting region near its surface. These surface conditions are combined with a coarse FE mesh inside the region for conveying slowly varying flux components. The correct impedance behaviour can thus be obtained in a wide frequency range, from DC flux on. The approach is briefly demonstrated by means of a simple 1D test case. [less ▲]

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See detailCombining Territorial Data With Thermal Simulations to Improve Energy Management of Suburban Areas
Marique, Anne-Françoise ULg; Petel, Maud; Hamdi, Asma et al

in Proceedings of GEOProcessing 2012 (2012, January)

Urban sprawl has been identified as a major issue for sustainable development. Energy consumption in suburban buildings, in particular, is a widespread issue because detached types of houses require ... [more ▼]

Urban sprawl has been identified as a major issue for sustainable development. Energy consumption in suburban buildings, in particular, is a widespread issue because detached types of houses require significantly more energy to be heated than more compact urban forms. Energy efficiency is often presented as a viable approach to the mitigation of climate change, but research and studies mainly contend with individual buildings and do not address this issue at larger territorial scales or for a whole building stock. In this respect, this paper first presents a morphological definition of urban sprawl. This definition uses territorial and cadastral data available for the Walloon region of Belgium. Using this definition, a suburban type classification adapted to thermal studies is drawn up. A representative block of each type is selected to model energy use and to determine the total energy consumption of the whole suburban building stock. An application is then presented concerning a comparison of potential energy savings associated with several renovation strategies. The results of this exercise are presented and highlight the benefits of combining Geographic Information Systems (GIS) tools, territorial data and thermal simulations for the efficient energy management of suburban areas at the scale of the whole building stock. [less ▲]

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See detailCombining the generalised likelihood uncertainty estimation (GLUE) and Bayesian model averaging (BMA) to account for conceptual model uncertainty in groundwater modelling
Rojas, Rodrigo; Feyen, Luc; Dassargues, Alain ULg

in Calibration and Reliability in Groundwater Modelling: Credibility in Modelling (Pre-Published Proc. of ModelCARE’2007) (2007)

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See detailCoMBiSpeC: A novel approach in the modelling of massive binaries
Palate, Matthieu ULg

Conference (2013, September)

Spectral modelling and especially for massive stars is not a straightforward problem and over the past decades many advances have been made in this field. We now have very efficient model atmosphere codes ... [more ▼]

Spectral modelling and especially for massive stars is not a straightforward problem and over the past decades many advances have been made in this field. We now have very efficient model atmosphere codes such as CMFGEN and TLUSTY for example. However, these codes are based on the assumption that the star is single and spherical which is no longer valid for the components of a binary system. On the other hand, observational studies indicate that binarity has an impact on the spectra and binary interactions impact the analyses of the spectra. This is why we have developed a very first model called CoMBiSpeC (code of massive binary spectral computation). We present here some examples of the impact of the binarity on the shape of the stars and the resulting effects on their spectra. [less ▲]

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See detailCoMBiSpeC: A novel approach in the modelling of massive binaries
Palate, Matthieu ULg

in EAS Publications Series (2014, February 01)

Spectral modelling and especially for massive stars is not a straightforward problem and over the past decades many advances have been made in this field. We now have sophisticated model atmosphere codes ... [more ▼]

Spectral modelling and especially for massive stars is not a straightforward problem and over the past decades many advances have been made in this field. We now have sophisticated model atmosphere codes that allow to derive the stellar parameters. However, these codes are based on the assumption that the star is single and spherical which is no longer valid for the components of a binary system. On the other hand, observational studies indicate that binarity has an impact on the spectra. This is why we have developed a model called CoMBiSpeC (code of massive binary spectral computation) that specifically accounts for the impact of binarity on the spectra. [less ▲]

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See detailCOMBOX: A Distributed Computing Process for Pre-Sizing of Composite Aircraft Box Structures
Krog, L.; Bruyneel, Michaël ULg; Remouchamps, Alain et al

Conference given outside the academic context (2007)

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See detailCombustion control and performance of household condensing boilers
Makaire, Danielle ULg; Ngendakumana, Philippe ULg

Poster (2011, April)

The present work presents a model that is composed of a conventional boiler model with a main counterflow gas-water heat exchanger at which a condensing heat exchanger is added. Prior to the second heat ... [more ▼]

The present work presents a model that is composed of a conventional boiler model with a main counterflow gas-water heat exchanger at which a condensing heat exchanger is added. Prior to the second heat exchanger the exhaust gas are converted to equivalent wet air as the wet heat exchanger is simulated by a cooling coil used in air treatment. Six parameters are needed for calculation and these parameters are fitted with experimental data: one test in dry regime and one test in wet regime. Steady-state tests have been performed on two household boilers (a gas-fired and a fuel oil boiler), whose nominal outputs are 24 kW in order to fit the model parameters and check the model behaviour. It seems that the model gives the correct trend for the thermal efficiency prediction. Besides, combustion controls sensors (non nernstian sensors) have been tested by varying the excess of air. In the range tested (from =1.05 to =1.25), the increase in the boiler efficiency is around 1% as the excess of air decreases. However that increase is lower than the measurement uncertainty. The developed model predicts very well that trend. The pollutants emissions have also been measured and the results show that the NOx emissions decrease as the excess air increases. [less ▲]

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See detailCombustion control by means of a photodiode
Ngendakumana, Philippe ULg; Tartari, Paula

in Proceedings of the 25th Task Leaders Meeting (TLM) of the IEA Implementing Agreement "Energy Conservation and Emissions Reduction in Combustion" (2003, September)

The objective of this work was to assess the feasibility of a photodiode to control combustion, instead of a spectrometer (which is an expensive sensor to be used in commercial burners). For that purpose ... [more ▼]

The objective of this work was to assess the feasibility of a photodiode to control combustion, instead of a spectrometer (which is an expensive sensor to be used in commercial burners). For that purpose, the flame emission has been measured in a hot-water boiler fired with light fuel-oil, whose nominal output power goes up to 370 kW. The parameters investigated were: overall air excess, combustion air distribution, burner power and atmospheric conditions. High influence of air distribution on the flame emission was detected by the diode, since it modifies directly the mixing quality reducing rich-fuel regions where soot can be formed. Low influence of air excess and burner power was found. When these parameters increase, the flame emission decreases. This behavior is explained by the better mixing attained at high burner power and at high air excess. However the high emission level observed at low firing rate can be reduced with a good burner adjustment. With the photodiode, it was possible to find the optimum air excess value where NO, CO and soot are as low as possible. As the photodiode measures locally in the flame, results were compared with images obtained with a CCD camera. Finally, these results are in good agreement with those obtained previously with the spectrometer. [less ▲]

Detailed reference viewed: 25 (2 ULg)