Lignocellulosic resources uses for savings of fossil fuels

Lignocellulosic biomass makes up the main part of the biomass produced in the world (12.1011 ton per year); relatively speaking, saccharose and starch make up a lower part (108t). Wood (from secondary-growth species) and related biomaterial from primarygrowth species (palms, coconut, bamboo) make up nearly 80% of lignocellulosic biomass produced in the world. The remaining part mainly comes from co-products of food plants (straw and co-products from cereals and oleaginous plants, bagasse...) and also annual plants produced for fibre (cotton, flax, hemp). A part of these fibres is used for other various applications than energy: pulp, biomaterial, and bioproducts. The wide range of celluloses- lignin-hemicelluloses distribution and structure of these biopolymers sometimes limit their applications. The development of these applications is also limited by two factors: (1) the collection and the transport of the fibres are not well organized; (2) the fibres must be frequently left on the ground after harvesting in order to maintain the soil fertility. Lignocellulosic materials play a major role to save fossil fuels for three main reasons: (1) their elaboration and their use need a low quantity of energy, by comparison with other materials; (2) lignocellulosic materials capture carbon during plant growth and store it during the life cycle of the manufactured products; (3) savings of energy are also possible when the biomaterials are used on the spot instead of imported materials, without long transport distances. It is economically interesting to produce energy from lignocellulosic biomass only if a part of this biomass is used as far as possible for higher added value applications, i.e. plant materials. Co-products and by-products used for energy are then obtained at lower cost. Lignocellulosic materials and energy applications are directly linked due to carbon storage in biomass that is used for energy at the end of life cycle. (Résumé d'auteur

Feasibility of a quantum memory for continuous variables based on trapped ions

We propose to use a large cloud of cold trapped ions as a medium for quantum optics and quantum information experiments. Contrary to most recent realizations of qubit manipulation based on a small number of trapped and cooled ions, we study the case of traps containing a macroscopic number of ions. We consider in particular the implementation of a quantum memory for quantum information stored in continuous variables and study the impact of the relevant physical parameters on the expected performances of the system.Comment: v2, typos correcte

Le contrat comme technique de participation des citoyens aux décisions en matière énergétique

Contractual techniques have known a remarkable development in French administrative law. Contractual relations between different government agencies and individuals have reflected a change in the relationship between the State, central agencies and corporations on one side, and local authorities, associations and individuals on the other. « Inequality, Hierarchy and Government Supervision » have been partially replaced by « Equality, Participation and Autonomy ». In this article, the author describes some instances where contractual techniques were used to promote the participation of local interests in energy decisions. He points out the consequences of such a technique of participation and concludes that its main problem is the representativeness of the participant

Inter- / inside-tree variations of reference wood characteristics of high value-added Central African timber species

The Central African wood sector is characterised by a steady but sometime short-lived commercialisation of new timber species on the local market as well as for regional or international trading. Wood manufacturers must identify the most suited species according to their own processing constraints in relationship with the specific wood properties of the selected species. According to these operators, wood variations quite only correspond to differences between species. However, important variations of physical and mechanical properties are observed on sawn timber, leading to bitter technological problems during processing. Some reference characteristics currently used to qualify technological behaviour of tropical species have been determined according to international standards or specific CIRAD's standard sampling procedure The analysis of the variations of some of these properties (shrinkages, fibre saturation point, hardness, Young's modulus) brought out the respective effect of several factors: basically, type of botanical species, but also differences between trees (linked to any diameter and age effect, even if very often, trees age is not known), and variations inside trees. Inter-species variations are frequently very high, but for some Central African timbers (i.e. Cylicodiscus gabunensis / OKAN, Pterocarpus soyauxii / PADOUK, Staudtia stipitata / NIOVE), intra-species variations can be higher. In particular, it is usually considered that intra-trees variations have not to be taken into account for timber from natural forest, and only concern plantations species. However, high variations inside trees have been observed for some species explaining some technological problems occurring during processing. These results shown that the study procedures to qualify tropical woods from plantations in one hand, and tropical woods from natural forests in the other hand, can be quite similar in some cases. Intra-species wood variations of timber from natural forest must be taken into account to improve appropriateness between their quality and their potential utilisation

Large 2D Coulomb crystals in a radio frequency surface ion trap

We designed and operated a surface ion trap, with an ion-substrate distance of 500\mum, realized with standard printed-circuit-board techniques. The trap has been loaded with up to a few thousand Sr+ ions in the Coulomb-crystal regime. An analytical model of the pseudo-potential allowed us to determine the parameters that drive the trap into anisotropic regimes in which we obtain large (N>150) purely 2D ion Coulomb crystals. These crystals may open a simple and reliable way to experiments on quantum simulations of large 2D systems.Comment: 4 pages, 4 figure

Absolute Single Ion Thermometry

We describe and experimentally implement a single-ion local thermometry technique with absolute sensitivity adaptable to all laser-cooled atomic ion species. The technique is based on the velocity-dependent spectral shape of a quasi-dark resonance tailored in a J $\rightarrow$ J transition such that the two driving fields can be derived from the same laser source leading to a negligible relative phase shift. We validated the method and tested its performances in an experiment on a single 88 Sr + ion cooled in a surface radio-frequency trap. We first applied the technique to characterise the heating-rate of the surface trap. We then measured the stationary temperature of the ion as a function of cooling laser detuning in the Doppler regime. The results agree with theoretical calculations, with an absolute error smaller than 100 $\mu$K at 500 $\mu$K, in a temperature range between 0.5 and 3 mK and in the absence of adjustable parameters. This simple-to-implement and reliable method opens the way to fast absolute measurements of single-ion temperatures in future experiments dealing with heat transport in ion chains or thermodynamics at the single-ion level

Application des techniques de traitement thermique et de reconstitution par collage pour valoriser le Pin maritime des Cévennes

Le développement des mines de charbon dans le Massif des Cévennes durant la 2èmemoitié du 19ème siècle est directement à l'origine de l'introduction du Pin maritime (Pinus pinaster Aiton) dans cette région pour la production d'étais de mine. Au début du 20èmesiècle, l'abandon progressif des mines a provoqué un développement de cette essence qui a colonisé les espaces abandonnés par l'agriculture. La montée en puissance de la filière-bois régionale est allée de pair avec une augmentation des besoins en bois auxquels le Pin maritime aurait pu répondre. Cependant, cette essence souffre localement d'une mauvaise image (mobilisation difficile, variabilité de la qualité intrinsèque du bois). Afin de démontrer ses potentialités technologiques et de confirmer ses perspectives de valorisation en bois d'oeuvre, une opération pilote de caractérisation technologique et de fabrication de produits à haute valeur ajoutée a été conduite. Ces produits devaient se démarquer des produits conventionnels en Pin des Landes (parquet, lambris, bardage, ...) face auxquels le Pin des Cévennes aurait été peu compétitif. Il a été ainsi décidé de cibler des produits et procédés à plus haute valeur ajoutée, produits d'ingénierie (= EWP, Engineered Wood Products) associés à des marchés plus rémunérateurs et à une demande croissante : produits collés de type panneaux BMR (Bois Massif Reconstitué), carrelets 3-plis, traitement thermique associé ou non à la fabrication de produits collés. Un échantillonnage de Pin maritime représentatif de la ressource cévenole a été constitué pour la réalisation d'essais de sciage, séchage, classement des bois sciés, caractérisation physique et mécanique, et fabrication de produits de démonstration. Ces essais ont donné des résultats prometteurs : sciage sans difficulté particulière et sans encrassement des lames malgré la résine abondante, séchage rapide sans apparition de défauts marqués, classement révélant une proportion importante de 1erchoix, caractéristiques physico-mécaniques soutenant la comparaison par rapport au Pin maritime des Landes. Le traitement thermique et la fabrication des carrelets 3-plis ont été réalisés chez des opérateurs industriels tandis que les panneaux de type BMR ont été fabriqués au CIRAD. Le traitement thermique a donné des résultats très positifs : bois très peu déformés, même pour les pièces à fort élancement, aucun développement de fissures dues au traitement. Les carrelets 3-plis aboutés ont été fabriqués à partir de bois traités et non traités thermiquement, en utilisant une colle vinylique D4 pour les aboutages, et une colle EPI (Emulsion Polymer Isocyanates) pour la lamellation. Les aboutages et la lamellation ont été qualifiés suivant la procédure définie dans la norme XP CEN/TS 13307-2 (2010-01-01). Selon les préconisations de cette norme, le collage est apparu satisfaisant aussi bien pour le Pin maritime non traité que pour le Pin maritime traité thermiquement (résistances des aboutages supérieures aux valeurs seuil, taux de délamination inférieur à 3%). L'ensemble des résultats obtenus a mis en évidence les réelles potentialités d'utilisation du Pin maritime des Cévennes. Envisager une meilleure valorisation de cette essences par rapport aux utilisations actuelles à faible valeur ajoutée implique de cibler les meilleures qualités de la ressource, au moins dans un premier temps. Les problèmes de difficultés d'approvisionnement et de mobilisation des bois restent cependant posés. (Texte intégral