References of "Pirard, Eric"
     in
Bookmark and Share    
Full Text
See detailUse of environmental isotopes to infer flow in the highly exploited aquifer system of the Diass region (Senegal)
Madioune, Diakher Hélène; Faye, Serigne; Dassargues, Alain ULg et al

Poster (2011, March 14)

The Diass horst multilayered aquifer constitutes a complex hydrogeological system. But stable isotopes are illustrated to be powerful tools for clarifying the origin of recharge water, and the groundwater ... [more ▼]

The Diass horst multilayered aquifer constitutes a complex hydrogeological system. But stable isotopes are illustrated to be powerful tools for clarifying the origin of recharge water, and the groundwater dynamics due to high exploitation of the system. Used with 3H and 14C, data confirms that most of the investigated groundwater are palaeowaters. Pumping has an impact on groundwater flow evidenced by the different water isotope compositions that illustrates the transient conditions of the system. Mixing of old waters and recently recharged (tritiated) waters occurs in some exploited boreholes, indicates lateral flow to the pumping field through the main groundwater flow directions. [less ▲]

Detailed reference viewed: 19 (1 ULg)
Full Text
Peer Reviewed
See detailParticle Size and Shape Characterisation - Current Technology and Practice
Hart, Jarrod; Zhu, Yingdan; Pirard, Eric ULg

in Christidis, George (Ed.) Advances in the Characterization of Industrial Minerals (2011)

Detailed reference viewed: 339 (16 ULg)
Full Text
See detailImage analysis for advanced characterization of industrial minerals and geomaterials
Pirard, Eric ULg; Sardini, Paul; Christidis, Georges

in Advanced Characterization of Industrial Minerals (2011)

Detailed reference viewed: 121 (15 ULg)
See detailParticle packing of concrete containing blended cement
He, Huan ULg; Courard, Luc ULg; Pirard, Eric ULg

Conference (2010, September 20)

Physical particle packing is becoming a hot topic in concrete technology as more and more types of granular materials are used in concrete either for ecological or for engineering purposes. Aggregate is ... [more ▼]

Physical particle packing is becoming a hot topic in concrete technology as more and more types of granular materials are used in concrete either for ecological or for engineering purposes. Aggregate is used as concrete’s skeleton, whereby the particles are stabilized by the cementitious matrix. Packing efficiency governs the spatial characteristics of this structure and thereby influences concrete’s properties. Fine-grained sand can be used to further improve density of the aggregate structure. The particulate cement is also frequently blended by fine mineral admixtures to influence performance of the paste and the properties of the matured concrete. The so-called filler effects increase packing density of the blended cement and possibly reduce water demand. High performance characteristics require suitable blending materials of proper properties (fineness, shape, chemical components, etc.). A number of theoretical packing models have been proposed for prediction of packing characteristics and the resulting concrete properties. A minimum voids ratio has been mathematically derived for certain particle size distributions. This allowed establishment of some optimum graded mixtures for concrete production. On the other hand, the computer simulation approach provides a powerful tool for simulating particle packing. Computational concrete (compucrete) has been developed for a wide range of research purposes. Application of computer simulation to particle packing offers a promising perspective in concrete technology; it provides a proper representation of the heterogeneous concrete material, and renders the possibility of studying the effects of a wide range of technological parameters. In this study, an advanced DEM will be utilized for investigate the packing properties of admixtures blended cement. This new-developed system is capable of packing simulations of arbitrary-shaped particles. Experimental shape analysis of each identical group of particles provides fundamental references of shape simulation strategy. Finally, computer simulation structures of blended cement paste both in fresh and hardened states will be compared with the experimental approach. Correlation of particle packing characteristics and properties of blended cement paste will be analyzed and discussed. Optimization of blending efficiency and improvement of concrete properties are pursued using packing modeling. [less ▲]

Detailed reference viewed: 93 (18 ULg)
Full Text
Peer Reviewed
See detailA history of early copper exploration in Katanga (D.R. Congo)
Pirard, Eric ULg

in Proceedings INHIGEO 2010 (2010, July)

The latest archeological findings suggest that malachite outcrops have been mined as early as the Vth century A.C. in Garangaze a province known nowadays as Katanga [1]. The pre-Bayeke tribes used to ... [more ▼]

The latest archeological findings suggest that malachite outcrops have been mined as early as the Vth century A.C. in Garangaze a province known nowadays as Katanga [1]. The pre-Bayeke tribes used to seasonally mine these outcrops and cast copper hansas (crosses) that were used as exchange goods and have been found all over the African continent even reaching Europe as early as the XVIth century through trade with the Portuguese and the Dutch Oud West Indisch Compagnie. The first explicit mention of copper in European texts is said to date back to March 22nd 1798 in a report made by pombeiros (afro-portuguese metis) to the hence governor of Rios de Sena (Mozambique) Francesco Jose Maria Lacerda [2]. Katanga has long remained as the most inaccessible region of the African continent. Despite attempts made by Livingstone until his death in 1873, by Cameron in 1874 and by Thomson in 1878, it was considered to remain for long out of reach [less ▲]

Detailed reference viewed: 191 (13 ULg)
Full Text
See detailInfluence of particle flatness and elongation on size distributions obtained from laser diffraction, static and dynamic image analysis.
Califice, Arnaud ULg; Michel, Frédéric ULg; Dislaire, Godefroid et al

in World Congress on Particle Technology (2010, April)

Detailed reference viewed: 54 (18 ULg)
Full Text
See detail3D and 2D particle image analysis of rock chips generated by core scratch tests.
Pirard, Eric ULg; Limam, Sami; Califice, Arnaud ULg et al

in World Congress on Particle Technology (2010, April)

Detailed reference viewed: 79 (9 ULg)
Peer Reviewed
See detailProcess mineralogy and automated phase identification in mixed copper ores at Kansanshi (Zambia)
Kottgen; Bastin, David ULg; Dufrane, Florent et al

Conference (2010)

Detailed reference viewed: 15 (0 ULg)
Full Text
Peer Reviewed
See detailQuantitative Microtexture Analysis of Carbonate Rocks Using Bireflectance Imaging
Jaimes Contreras, Rafael Antonio ULg; Pilawski, Dimitri; Califice, Arnaud ULg et al

in Proceedings IAMG 2010 (2010)

Microtextural analysis of rocks has been addressed by several authors as an essential means to better understand the natural genesis of the material. But, it is also of paramount importance to those who ... [more ▼]

Microtextural analysis of rocks has been addressed by several authors as an essential means to better understand the natural genesis of the material. But, it is also of paramount importance to those who try to predict the geotechnical or industrial behaviour of a rock under many forms of solicitation (mechanical, thermal, etc.). Quantitative modal (phase) analysis using point counting has already been discussed in depth by authors such as Chayes more than fifty years ago. Nowadays, automated image analysis with millions of pixels is easily available and improves statistical accuracy provided the classification step is correctly performed. Spitefully the assignment of a pixel to a given mineral phase or to a given crystal is often poorly satisfactory and remains the bottleneck of a fully automated textural analysis. Methods using a manual rotation of a polarizer in transmitted light microscopy have been developed by Starkey and Samantaray (1993) and further automated and improved by Fueten (1997). These allow to better delineate individual crystals in a thin section due to contrast in birefringence. In this paper a similar technique using multiple orientations of a polarizer in reflected light microscopy has been used to contrast individual crystals in carbonated rocks. The maximum and minimum grey levels registered for each pixel allow for computing a bireflectance image whose variance is a good indicator of the misalignment of cristallographical orientations in the section. Moreover, the maximum of the reflectance gradient obtained for each orientation generates a good image of the grain boundaries and the presence of pores. This last one is quantitatively analysed using the intercept method to estimate the mean and variance of the grain size distribution. The paper presents a quantitative comparison of several different microtextures. [less ▲]

Detailed reference viewed: 153 (8 ULg)
Full Text
Peer Reviewed
See detailEvaluating a calibration method for the estimation of fragmented rocks 3D-size-distribution out of 2D images
Outal, Souhail; Schleifer, Jacques; Pirard, Eric ULg

in Sanchidrian, J. A. (Ed.) Fragblast 9 (2009)

Image analysis is a tool having great potential for the quantification of fragmented rocks size-distribution. This recent technique should be validated according to sieving measurements. Current acquisi ... [more ▼]

Image analysis is a tool having great potential for the quantification of fragmented rocks size-distribution. This recent technique should be validated according to sieving measurements. Current acquisi-tion allows the obtaining of only 2D information from images. In addition, the 3D passage is extremely prob-lematic. Firstly, the usual stereological methods do not work because the reasoning is carried out on non-random projections. Secondly, estimated sizes differ from those measured by sieving. Last, a quantity of mat-terial measured during sieving remains inaccessible by image analysis, due to masking and segregation. This paper evaluates a method directly connecting 2D raw data to 3D sieving measurements. The cited problems are reduced as much as possible thanks to the adoption of an isotropic 2D sorting criterion, and thanks to samples without masking and segregation. Important results have been obtained. Firstly, the characteristic size is correctly estimated in 2D, giving access to computing the uniformity index through known models. Secondly, the stereological approach, bringing into play proportions, is not sufficiently robust to reconstruct easily volume distributions. Limits of this kind of methods, which are, unfortunately, currently used in several granulometric applications, are analyzed. [less ▲]

Detailed reference viewed: 74 (1 ULg)
Full Text
See detailUsing Artificial Vision for the Microscopic Identification of Ores with Reflected Light: Preliminary Results.
Castroviejo, Ricardo; Brea, Carolina; Perez-Barnuevo, Laura et al

in Proceedings 10th Biennial SGA Meeting (2009)

Detailed reference viewed: 32 (3 ULg)
Full Text
See detailENVIRONMENTAL ASPECTS OF CLAY EXPLOITATION FOR FIRED CLAY BRICKS IN CAMEROON
Njoya, A.; Bastin, D.; Melo, U. et al

Poster (2009)

Detailed reference viewed: 49 (12 ULg)
Full Text
Peer Reviewed
See detailPrediction of acid mine generating potential: Validation using mineralogy
Bouzahzah, Hassan; Benzaazoua, Mostafa; Plante, Benoît et al

in Proceedings 24th International Applied Geochemistry Symposium (2009)

Detailed reference viewed: 48 (8 ULg)
Full Text
See detailCaracterización y cuantificación autmatizadas de menas metálicas mediante visión artificial : proyecto cameva
Castroviejo, Ricardo; Catalina, Juan-Carlos; Bernhardt, Heinz-Juergen et al

in Actos del XIII Congreso Latino Americano de Geologia (2008)

The CAMEVA project (Automated system for the identification and quantitative measurement of ore minerals) aims to develop an automated system able to perform the identification and quantification of the ... [more ▼]

The CAMEVA project (Automated system for the identification and quantitative measurement of ore minerals) aims to develop an automated system able to perform the identification and quantification of the different minerals present in a sample of metallic ores, in order to facilitate their industrial use. The system comprises a motorised reflected light microscope, a filter wheel (monochromator), a research BW camera, and a computer running a digital image analysis software associated to an expert system specially developed for this application. Multispectral reflectance values are measured for visible light and near IR and UV (350-1000 nm), and no polarisation is usually employed in order to reduce measurement variability due to mineral anisotropy. Mineral identification is carried out by comparison of measured reflectances with spectral reflectance databases (e.g. IMA-COM). Previous experiences showed that the most common ores can be differentiated through the analysis of a microscopic RGB colour image, by constraining the search with additional information such as the type of deposit and the corresponding mineral association. The project goes further, and intends to identify most of the ores from multi-spectral images, including non-visible bands, resorting to an expert system specifically built to deal with the different types of information available (spectral reflectance, sample origin, mineral associations, morphology, etc). 2 Validation of the method will be carried out by comparative análisis of standards and samples exchanged between the laboratories. Development pays special attention to the total automation of the process (including calibration) and to the self-learning capabilities of the system. Contacts with research institutions and with the industry will allow to apply the system to real problems. The system can be used to control the processing of ores as well as to prevent pollution for the protection of the environment (e.g. sulphides in coal or in industrial tailings). Further applications can be envisaged in the future: e.g. other minerals, coal or materials, particles, etc. [less ▲]

Detailed reference viewed: 73 (1 ULg)
Full Text
Peer Reviewed
See detailLandslide Detection Methods, Inventory Analysis and Susceptibility Mapping Applied to the Tien Shan, Kyrgyz Republic.
Danneels, Gaëlle; Havenith, Hans-Balder ULg; Strom, A. et al

in Proc. of the First World Landslide Forum (2008)

This paper presents results of the last five years of landslide detection and landslide susceptibility mapping in the Central and Southern Tien Shan. Landslide inventories have been compiled for areas of ... [more ▼]

This paper presents results of the last five years of landslide detection and landslide susceptibility mapping in the Central and Southern Tien Shan. Landslide inventories have been compiled for areas of major interest in the Kyrgyz Republic. For those areas, landslides were first mapped manually using KFA satellite images and aerial photographs. Recently, a landslide detection method has been developed in order to map landslides automatically. This method is based on a neural network scheme applied to detect particular slope failure features from remote sensing data. Multi-spectral and/or panchromatic ASTER and SPOT images as well as digital elevation models (DEMs) are used as inputs. This automatic method is designed to map medium-size mass movements (105-107 m3). This approach supplements the manual mapping of large slope failures and helps to complete the inventory of mass movements and related landslide susceptibility/hazard maps for large areas within the Tien Shan. Size-frequency analyses have been applied to the two existing regional landslide inventories. These size-frequency analyses revealed the incompleteness of the respective inventories (in the low-size domain) as well as regional and local differences due to natural and anthropogenic influences. To be able to perform reliable susceptibility and size-frequency analyses, the completed inventories need to be verified. At present, we perform local verification by manual mapping and control, but automatic verification methods are being developed. They will also allow us to determine the level of uncertainties. Ongoing research is focused on the propagation of uncertainties throughout the chain of processing. [less ▲]

Detailed reference viewed: 174 (11 ULg)
Full Text
Peer Reviewed
See detailFrom spectrophotometry to multispectral imaging of ore minerals in visible and near infrared (VNIR) microscopy.
Pirard, Eric ULg; Bernhardt, Heinz-Juergen; Catalina, Juan-Carlos et al

in GU; BUTCHER (Eds.) Proceedings of ICAM 2008 (2008)

Detailed reference viewed: 44 (6 ULg)