Hydraulic studies for the Taoussa project, Mali

in Proceedings of Africa 2013 conference (CD-Rom) (2013)

The Taoussa Project is a component of a large development scheme of the Niger River in the north-eastern part of Mali aiming at reducing desertification and improving socio-economic activity. It is mainly ... [more ▼]

The Taoussa Project is a component of a large development scheme of the Niger River in the north-eastern part of Mali aiming at reducing desertification and improving socio-economic activity. It is mainly made of a rockfill dam with central core around 18 m high and 1,000 m long across the valley of the Niger River, 130 km upstream of the town of Gao in the eastern part of Mali. The dam is equipped with a 25 MW hydroelectric power plant, a lock, a dock and a spillway. The spillway is made of a gated ogee crested weir divided into 10 bays and a downstream stilling basin, with a maximum discharge capacity of 3,100 m³/s. 210 km of high tension overhead cables and a 130 km long road complete the Project. The multipurpose Taoussa dam will enable the sustainable development of the Project area by securing water resources, increasing low-water level discharges downstream, creating a link between road and fluvial transports (dock) and producing electricity. The Ministère de l’Energie, des Mines et de l’Eau du Mali - Autorité pour l’Aménagement de Taoussa -commissioned Coyne et Bellier – Tractebel Engineering in 2006 to perform the detailed studies for the Project. In this framework, the hydraulic studies have been performed by the Laboratory of Engineering Hydraulics (HECE) of the University of Liege. These hydraulic studies, depicted in details in the paper, have been carried out successively by two complementary approaches: a first step realized on the basis of numerical modelling to study the flows at the scale of the reservoir and the river, and a second experimental investigation, using a scale model, to analyse in details the spillway operation conditions. They consider varied problems from large scale flow conditions in the reservoir during the spillway operation and hydrodynamic interactions between the dam, the lock and the hydroelectric power plant to validation and optimization of the hydraulic design and dimensions of the gated spillway and the stilling basin or release conditions downstream of the project structures, including the temporary derivation stage. [less ▲]

The abundance of charcoal fragments emphasizes the assumption of huge palaeofires in the mixed moist semi-evergreen rainforest of the northern republic of Congo

in Damblon, Freddy (Ed.) Proceedings of the Fourth International Meeting of Anthracology (2013)

In this paper, we study the origins of the northern Congo Republic rainforests. Macroscopic charcoal fragments were systematically recorded through auger investigations and pits observations in four ... [more ▼]

In this paper, we study the origins of the northern Congo Republic rainforests. Macroscopic charcoal fragments were systematically recorded through auger investigations and pits observations in four forest types: the open canopy Marantaceae forest, the dense forest with Marantaceae, the Gilbertiodendron dewevrei forest and the Triplochiton scleroxylon forest. In addition, the charred Elaies guineensis seeds were distinguished from the other charcoals in the pits. Ten selected charcoals, including charred E. guineensis seeds, were dated by AMS. Abundance of charcoal fragments in the soils at various depths indicated several episodes of fires in the region. A dryer climatic phase, between 2320 and 1330 BP, associated with a large scale human occupation related to the important harvesting of oil palm nuts, could explain the widespread Marantaceae forests. Recent slash-and-burn shifting cultivation, c. 200 BP, would allow T. scleroxylon installation. Implications for forest management are discussed. [less ▲]

The African coelacanth genome provides insights into tetrapod evolution.

in Nature (2013), 496(7445), 311-6

The discovery of a living coelacanth specimen in 1938 was remarkable, as this lineage of lobe-finned fish was thought to have become extinct 70 million years ago. The modern coelacanth looks remarkably ... [more ▼]

The discovery of a living coelacanth specimen in 1938 was remarkable, as this lineage of lobe-finned fish was thought to have become extinct 70 million years ago. The modern coelacanth looks remarkably similar to many of its ancient relatives, and its evolutionary proximity to our own fish ancestors provides a glimpse of the fish that first walked on land. Here we report the genome sequence of the African coelacanth, Latimeria chalumnae. Through a phylogenomic analysis, we conclude that the lungfish, and not the coelacanth, is the closest living relative of tetrapods. Coelacanth protein-coding genes are significantly more slowly evolving than those of tetrapods, unlike other genomic features. Analyses of changes in genes and regulatory elements during the vertebrate adaptation to land highlight genes involved in immunity, nitrogen excretion and the development of fins, tail, ear, eye, brain and olfaction. Functional assays of enhancers involved in the fin-to-limb transition and in the emergence of extra-embryonic tissues show the importance of the coelacanth genome as a blueprint for understanding tetrapod evolution. [less ▲]

Dimensionnement et modélisation d'une micro-centrale solaire

Poster (2013)

Processing of Ti alloys by additive manufacturing: a comparison of the microstructures obtained by laser cladding, selective laser melting and electron beam melting

in Materials Science Forum (2013), 765

Additive manufacturing processes such as laser cladding (LC) or selective laser melting (SLM) appear very promising in view of an economic near-net-shape production – and also, in the case of LC, the ... [more ▼]

Additive manufacturing processes such as laser cladding (LC) or selective laser melting (SLM) appear very promising in view of an economic near-net-shape production – and also, in the case of LC, the restoration - of complex and (almost) fully dense parts from Ti alloys. Both techniques involve the melting of a metallic powder with a laser. In the SLM process, the metallic powder is deposited layer by layer in a powder bed and then molten locally according to the desired shape, whereas in LC, the metallic powder is directly projected onto a substrate through a nozzle coaxial with the laser beam. The present research aims at comparing Ti-6Al-4V samples processed by these two techniques with reference samples produced by electron beam melting (EBM), another well established additive manufacturing process (patented by Arcam AB Company) in which a powder bed is molten locally by means of an electron beam. In all three processes, the melt pool undergoes an ultrafast cooling and solidifies very rapidly once the beam has left the area, thus giving rise to strongly out-of-equilibrium microstructures. Yet, each one of these processes also has its own specificities e.g. in terms of scanning strategy and of working atmosphere (low vacuum vs. protective Ar flow). In the present work, the microstructures obtained by these three processes have been compared in details, with a particular attention for characteristics such as porosity, grain size, and the various phases present. Since epitaxial growth of the newly deposited layer on the material previously solidified has been shown [1, 2] to exert a strong influence on the microstructure and on the resulting mechanical properties, great care has been taken to study the microstructural anisotropy associated with each one of the three processes. [less ▲]

Lo que los Sistemas Nacionales de Innovación no miran. Una crítica constructiva de las políticas de ciencia y tecnología a partir del ‘modelo de la soja transgénica’

in Tula Molina, Fernando; Vara, Ana Maria (Eds.) Riesgo, política y alternativas tecnológicas. Entre la regulación y la discusión pública (2013)

En todo el mundo, las políticas y planes estratégicos de ciencia, tecnología e innovación (CTI) integran y reproducen una narrativa de innovación para el desarrollo a través del crecimiento económico ... [more ▼]

En todo el mundo, las políticas y planes estratégicos de ciencia, tecnología e innovación (CTI) integran y reproducen una narrativa de innovación para el desarrollo a través del crecimiento económico, utilizando conceptos tales como “sistemas nacionales de innovación” (SNI) (Lundvall, 1992) o “sociedad del conocimiento” o “economía del conocimiento”. Incluso si este modelo de innovación no es ideal o no está adaptado a las realidades locales, ha sido propuesto una y otra vez por organismos internacionales de crédito como el Banco Mundial, el Fondo Monetario Internacional o Banco Interamericano de Desarrollo. La ecuación que está en el corazón de esta narrativa ha sido siempre la misma: fomentar la innovación (e invirtiendo para fortalecer su lugar en la economía nacional) llevará indefectiblemente a mayores beneficios económicos que en última instancia ayudarán a mejorar el nivel de bienestar social. De hecho, al minimo al nivel del discurso institucional, los sistemas nacionales de innovación existen (o hay promesas acerca de que van a existir) en todo lugar en que haya innovación. Volver real y eficiente el sistema se presenta como una precondición para la competitividad y el desarrollo futuro. En la realidad sin embargo, estos sistemas apenas existen en los mayores países en desarrollo, en función de las características del entramado institucional existente, las características de los actores locales, la falta de recursos materiales y simbólicos, los fuertes lazos de dependencia económica y las amplias desigualdades sociales. De modo central, y sin que exista necesariamente una reflexión acerca de si ese camino es el más indicado, tomar el camino de la “sociedad del conocimiento” seriamente, al establecer una estructura institucional para un sistema nacional de innovación, se transforma en el motor para el financiamiento de nuevas políticas públicas. Si la innovación finalmente tiene lugar, esto puede significar también que el poder ha sido desigualmente distribuido entre un número de actores que participaron, de una u otra forma, de un proceso sistémico complejo que pudo involucrar la extracción de recursos naturales, la investigación fundamental y aplicada, desarrollos industriales y márgenes de competitividad que llevaron a mayores beneficios. Este proceso pudo haber implicado la participación activa de los diferentes stakeholders, y la confrontación de diferentes líneas de argumentos, visiones económicas y prioridades socio-políticas. La mayoría del tiempo, cuando los países en desarrollo adoptan la narrativa de la “innovación para el desarrollo”, caen víctimas de un discurso dominante que está arraigado o relacionado con una estructura hegemónica (Radaelli, 2000), un patrón consistente que refleja la colonialidad del poder (Quijano, 2000). En un artículo reciente, Delvenne y Thoreau (2012) se ocupan del influyente y extendido enfoque de los Sistemas Nacionales de Innovación y discuten su adecuación a países que no son miembros de la OCDE, especialmente en América Latina donde tiende a ser reificado. A pesar de que el enfoque de los SNI supuestamente está pensado para abordar las necesidades más urgentes de las economías a las que se aplica, los autores señalan que se beneficiaría con el desarrollo de una visión más abarcativa, que permita integrar mayor diversidad y complejidad. En este capítulo, nos apoyaremos en primer término en su diagnóstico y lo articularemos con la historia del régimen de CTI en América Latina, con un foco especial en Argentina. En un segundo momento, a través de una visión general del caso de la soja transgénica y su importancia para la balanza de pagos de Argentina, exploramos la siguiente paradoja: mientras numerosos académicos señalan la necesidad de desarrollar una agenda de innovación para los países del sur, con un “marco sureño de pensamiento” (Arocena y Sutz, 2003), los planes nacionales de CTI y los desarrollos actuales en biotecnología siguen descansando en una versión reduccionista de la innovación que impide que esta “perspectiva sureña” pueda emerger, y los limita a metas económicas, considerando las aspectos sociales y ecológicos como meras externalidades. Nos proponemos explorar las razones detrás de esta situación y observamos que esto tiene un impacto en los actores que desean utilizar la CTI de modo más reflexivo, a la vez que también en la eficiencia de las políticas de CTI en Argentina. Nuestra intención no es la de criticar ciegamente la orientación de las políticas CTI hacia el crecimiento económico, sino más bien contribuir -a través de un excelente ejemplo de un sector central de la economía argentina- a introducir una perspectiva más crítica y abarcativa de estas políticas públicas. [less ▲]

Quel(s) futur(s) pour la Forêt de Soignes ? Adéquation des essences à leurs stations face aux changements climatiques

in Silva Belgica (2013), 120(2), 14-19

On sait maintenant, depuis une dizaine d'années que les hêtraies des plaines européennes vont largement souffrir des modification climatiques en cours. En forêt de Soignes, l'augmentation de la ... [more ▼]

On sait maintenant, depuis une dizaine d'années que les hêtraies des plaines européennes vont largement souffrir des modification climatiques en cours. En forêt de Soignes, l'augmentation de la température prévue pour la fin de ce siècle sera sensible (référence pour la basse et la moyenne Belgique : Laurent et al., 2009) de plusieurs degrés et surtout en période estivale, et sera couplée à des périodes sans pluie. Ce nouveau climat correspondra plus ou moins au climat actuel du Sud de la Loire, une région au paysage forestier largement dépourvu de hêtre. Dans ce cadre, Bruxelles Environnement a chargé Gembloux Agro-Bio Tech de faire le point sur la situation actuelle et future de l'adéquation de ses essences de production de la forêt de Soignes à son milieu, à l'échelle de la station. [less ▲]

Ab initio calculation of spin-dependent electron-phonon coupling and transport in iron and cobalt

in Journal of Physics : Condensed Matter (2013), 25

The spin-dependent coupling between electrons and phonons in ferromagnetic Fe and Co is calculated from first principles in a collinear-spin formalism. The added spin polarization is fundamental for the ... [more ▼]

The spin-dependent coupling between electrons and phonons in ferromagnetic Fe and Co is calculated from first principles in a collinear-spin formalism. The added spin polarization is fundamental for the correct representation of the phonons, but also to obtain good transport properties, and permits the decomposition (e.g. of the resistivity) into the contributions of majority and minority spin. In Fe the minority spin coupling is only about 50\% more important, but in Co the coupling between phonons and minority spin electrons is an order of magnitude larger than majority, and both are strongly anisotropic. [less ▲]

Maigret et le clochard, un polar existentiel et poétique adapté à la télévision

in Demoulin, Laurent (Ed.) Cahier de l'Herne Simenon (2013)

Maigret et le clochard est un roman policier qui explore les limites du genre au point de pouvoir être envisagé comme un roman poétique ou existentiel. Qu'en est-il alors de son intrigue policière? Et ... [more ▼]

Maigret et le clochard est un roman policier qui explore les limites du genre au point de pouvoir être envisagé comme un roman poétique ou existentiel. Qu'en est-il alors de son intrigue policière? Et comment les scénaristes qui ont adapté ce roman pour la télévision ont-il traité cette intrigue inhabituelle? [less ▲]

Utilization of Large White x Mong Cai crossbred sows, Duroc and stress negative Piétrain boars for the production of fattening pigs under household conditions in northern Vietnam

in Animal Production Science (2013), 53 (Accepted)

The objective of the present study was to compare Duroc (DU) and stress-negative Piétrain (PI) as terminal sires mated to F1(Large White x Mong Cai) sows (F1) on productivity, carcass characteristics ... [more ▼]

The objective of the present study was to compare Duroc (DU) and stress-negative Piétrain (PI) as terminal sires mated to F1(Large White x Mong Cai) sows (F1) on productivity, carcass characteristics, meat quality and meat chemical composition under household conditions in Hai Duong province, Vietnam. The reproduction performances were based on 74 litters of 42 F1 sows from 12 households and the semen from 11 Duroc and 10 Piétrain boars. Data on production and carcass traits were collected from 76 DUxF1and 67 PIxF1 crossbred fattening pigs. Longissimus dorsi samples from 55 and 37 of DUxF1 and PIxF1 respectively were analyzed to determine meat quality and meat chemical composition. The results show that household affected production, carcass, and meat quality traits (P<0.05) as well as reproduction (weights at birth and weaning, P<0.01). Inversely, boar breeds did not influence (P>0.06) on reproduction traits (except individual weight of born alive pigs and weaned pigs, P<0.01), production traits, meat chemical composition and meat quality (except pH at 4 days post mortem, P<0.05) while lean meat percentage of Piétrain-sired pigs was higher than those of Duroc-sired pigs (P<0.05). The utilization of Piétrain boars does not affect reproduction performances, growth rate and meat quality while improving lean meat percentage in comparison to Duroc boars. This suggests that the use of stress-negative Piétrain boars as terminal sires would improve lean meat percentage under household conditions in North Vietnam. [less ▲]