Climate change, in the framework of the Constructal Law

Here we present a simple and transparent alternative to the complex models of earth’s thermal behaviour under time-changing conditions. We show the one-to-one relationship between changes in atmospheric properties and time-dependent changes in temperature and its distribution on earth. The model accounts for convection and radiation, thermal inertia and changes in albedo (ρ) and greenhouse factor (γ). The constructal law is used as the principle that governs the evolution of fl ow confi guration on earth. The model showed that for two time-dependent scenarios, (δρ = 0.002; δγ = 0.011) and (δρ = 0.002; δγ = 0.005) the predicted equatorial and polar temperature increases and the time scales are (ΔTH = 1.16 K; ΔTL = 1.11 K; 104 years) and (0.41 K;0.41 K; 57 years), respectively. A continuous model of temperature variation was used to predict the thermal response of the Earth’s surface to changes bounded by δρ = δγ and δρ = −δγ. The poleward heat current reaches its maximum in the vicinity of 35° latitude,accounting for the position of the Ferrel cell between the Hadley and Polar Cells

NUMERICAL PARAMETRIC STUDY ON CO2 CAPTURE BY INDIRECT THERMAL SWING ADSORPTION

International audiencePost-combustion CO2 capture remains one of the most-challenging issue to lower CO2 emissions of existing power plants or heavy industry installations because of strong economy and energy efficiency aspects. The major issue comes from CO2 dilution (4% for NGCC and 14% for PC) and the high flow rates to be treated. Furthermore, CO2 purity has to be higher than 95% with recovery at 90%, to match the transportation/injection requirements. The MEA absorption process remains the reference today but its energy consumption (about 3 MJ/kgCO2) and the amine consumption are still challenging drawbacks. The interest of CO2 capture by indirect TSA (Temperature Swing Adsorption) was demonstrated experimentally in a previous work. The aim of this paper is to present the results of a numerical parametric study. Two main parameters are explored: the desorption temperature (100 to 200 °C) and the purge flow rate (0.1 to 0.5 Ndm 3 .min-1). Four performance indicators are evaluated: CO2 purity, recovery, productivity and specific energy consumption. Results show that purity above 95% can be achieved. Keeping the 95% target, it is possible to achieve recovery at 81% with productivity at 57.7 gCO2/kgads.h and a specific 2 energy consumption of 3.23 MJ/kgCO2, which is about the same level than for up to date MEA processes. Comparison with other adsorption processes exhibits that this process has good potential especially since some improvements are still expected from further research

Influence of the Presence of CO2 in the Feed of an Indirect Heating TSA Process for VOC Removal

International audienceThis work deals with an experimental study of an indirect temperature swing adsorption process for VOC removal from air or for gas purification. A 1 m long and 70 mm diameter column with an internal heat exchanger has been filled with Ambersorb 600 carbonaceous adsorbent. This column is equipped with sensors to measure temperature at several points inside the bed, as well as the inlet and outlet gas concentration, pressure, temperature and mass flow. In a first step, CO2 or ethane/ dry nitrogen mixtures were used to simulate a single VOC in air, with different concentrations (350 ppm, 1% and 10%). As a first results very effective gas purification was obtained and an advantage of this process is the high pollutant concentration during the regeneration phase. Experiments were performed with various ethane/CO2 mixtures. The influence of the presence of CO2 on the ethane concentration breakthrough curves and on the ethane concentration during regeneration is reported. The IAS theory was used, as a first approach, to predict the adsorbed pollutants amount. Relatively good prediction is obtained with a maximum error in the order of 10%. An energy balance study is reported as well

Mechanistic studies on DNA damage by minor groove binding copper–phenanthroline conjugates

Copper–phenanthroline complexes oxidatively damage and cleave nucleic acids. Copper bis-phenanthroline and copper complexes of mono- and bis-phenanthroline conjugates are used as research tools for studying nucleic acid structure and binding interactions. The mechanism of DNA oxidation and cleavage by these complexes was examined using two copper–phenanthroline conjugates of the sequence-specific binding molecule, distamycin. The complexes contained either one or two phenanthroline units that were bonded to the DNA-binding domain through a linker via the 3-position of the copper ligand. A duplex containing independently generated 2-deoxyribonolactone facilitated kinetic analysis of DNA cleavage. Oxidation rate constants were highly dependent upon the ligand environment but rate constants describing elimination of the alkali-labile 2-deoxyribonolactone intermediate were not. Rate constants describing DNA cleavage induced by each molecule were 11–54 times larger than the respective oxidation rate constants. The experiments indicate that DNA cleavage resulting from β-elimination of 2-deoxyribonolactone by copper–phenanthroline complexes is a general mechanism utilized by this family of molecules. In addition, the experiments confirm that DNA damage mediated by mono- and bis-phenanthroline copper complexes proceeds through distinct species, albeit with similar outcomes

Gait analysis with curvature maps: A simulation study

Gait analysis is an important aspect of clinical investigation for detecting neurological and musculoskeletal disorders and assessing the global health of a patient. In this paper we propose to focus our attention on extracting relevant curvature information from the body surface provided by a depth camera. We assumed that the 3D mesh was made available in a previous step and demonstrated how curvature maps could be useful to assess asymmetric anomalies with two simple simulated abnormal gaits compared with a normal one. This research set the grounds for the future development of a curvature-based gait analysis system for healthcare professionals.Comment: 4 pages, 5 figure

Caractérisation expérimentale, modélisation thermomécanique et étude de la fatigue de pièces en alliages à mémoire de forme (AMF)

Description de la déformation dans les alliages à mémoire de forme -- Transformation martensitique thermoélastique dans les AMF -- Variantes de martensites -- Autoaccommodation -- Induction de variantes préférentielles sous contrainte -- Transformation dans les AMF vs les aciers -- Autres aspects de la germination et de la croissance -- Phénomènes reliés à la fatigue -- Déformations dans les AMF -- Mémoire de forme -- Sollicitations cycliques -- Cycles thermomécaniques -- Cycles thermomécaqniques divers -- Évolution du matériau -- Dégradation de l'effet mémoire -- Restauration du matériau fatigué par traitement thermique -- Caractéristiques en fatigue des alliages existants -- Considérations pour la modélisation de la fatigue de l'effet mémoire -- Simulations de cycles de fatigue -- Approche micromécanique -- Modèles de comportement thermomécanique AMF -- Modélisation uniaxiale non-linéaire (krigamf) -- Modélisation dans un contexte de design de pièces AMF -- Modélisation triaxiale -- Passage de Krigamf vers la modélisation triaxiale -- Caractérisation, modélisation et calculs de ressorts hélicoidaux -- Calcul de ressorts hélicoïdaux AMF -- Modélisation du matériau AMF -- Résultats de calculs de ressorts hélicoïdaux AMF -- Ressort de Gillet et effets du nombre d'éléments -- Comparaison entre les résultats de calcul et les courbes expérimentales -- Effets des erreurs de caractérisation et de modélisation sur les résultats de calculs

Les structures de connaissances

Présentation d'un projet de recherche sur l'utilisation des réseaux sémantiques comme aide à l'apprentissage en biologie