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A geometry-preserving finite volume method for compressible fluids on Schwarzschild spacetime,
No full text22 pagesInternational audienceWe consider the relativistic Euler equations governing spherically symmetric, perfect fluid flows on the outer domain of communication of Schwarzschild spacetime, and we introduce a version of the finite volume method which is formulated geometrically (without choosing coordinates a priori) and is well--balanced, in the sense that it preserves steady solutions to the Euler equations on the curved geometry under consideration. In order to formulate our method, we first derive a closed formula describing all steady and spherically symmetric solutions to the Euler equations posed on Schwarzschild spacetime. Second, we describe a finite volume method which is formulated geometrically from the family of steady solutions to the Euler system. Our scheme is second--order accurate and, as required, preserves the family of steady solutions at the discrete level. Numerical experiments are presented which demonstrate the efficiency and robustness of the proposed method even for solutions containing shock waves and nonlinear interacting wave patterns. As an application, we investigate the late--time asymptotics of perturbed steady solutions and demonstrate its convergence for late time toward another steady solution, taking the overall effect of the perturbation into account
Pheromone identification of the cedar shoot moth Dichelia cedricola Diakonoff (Lepidoptera: Tortricidae)
No full textInternational audienceThe cedar shoot moth, Dichelia cedricola Diakonoff, is considered as an important defoliator of the Lebanese cedars, Cedrus libani in Lebanon and Turkey. A recent outbreak revealed the need for a new tool to monitor the population within an integrated forest health management approach. To achieve this objective, a sex pheromone was identified by using solid phase microextraction (SPME) of calling female head space and female gland extracts, analyzed by gas chromatography/mass spectrometry. The biological activity of the identified components was assessed by field trapping in the Lebanese cedar forests. (Z)-11-tetradecenyl acetate and (Z)-11-tetradecen-1-ol were identified as the sex pheromone components of D. cedricola. The field studies showed that (Z)-11-tetradecenyl acetate and (Z)-11-tetradecen-1-ol (65:35) is an efficient formulation. The chemical composition is discussed in the view of biosystematics within Archipini tribe. These findings will contribute to the implementation of an integrated management program using the pheromone of D. cedricola and the assessment of the pest presence or absence in the cedar forest ecosystems of the Mediterranean regions
First assessment of triclosan, triclocarban and paraben mass loads at a very large regional scale: case of Paris conurbation (France).
No full textInternational audienceThe objective of this study was to examine the occurrence of parabens (5 congeners), triclosan (TCS) and triclocarban (TCC) at the scale of the Parisian sewer network and to provide representative knowledge on these compounds in France for a large area. For this purpose and in collaboration with the Parisian public sanitation service (SIAAP) in charge of the collect and treatment of the Parisian wastewater, this study focused on seven main sewer trunks of the Paris conurbation, accounting for 1900,000 m(3) d(-1), i.e., about 8 million inhabitants. Concentrations lying in the 2000-20000 ng l(-1) ranges were found in wastewater, confirming the ubiquity of parabens, TCS and TCC in our environment and household products. Parabens (>97%) and to a lesser extent TCS (68% in median) were mainly associated to the dissolved fraction, as demonstrated by low KD and KOC values. For the first time, this study also evaluated the pollutant mass loads per population equivalent (PE) of parabens, TCS and TCC at the large and representative scale of the Parisian conurbation. Hence, the median mass loads varied from 176 to 3040 μg PE(-1) d(-1) for parabens and from 26 to 762 μg PE(-1) d(-1) for TCS and TCC. Based on these results and according to the assumptions done, the extrapolation of the mass loads at the national scale pointed out an annual mass loads between 51.8 and 100.7 ty(-1) for methyl paraben (MeP) and between 11.2 and 23.5 ty(-1) for TCS. Mass loads per equivalent habitant and national mass loads are both extremely relevant and innovative data. Contrary to other countries, such data are nowadays rather difficult to gain in France and neither enquiry nor database provides access to information on the use and production of these chemicals. Since cosmetic industries are voluntarily and fully engaged in the substitution of parabens, triclosan and triclocarban in personal care product, this study could constitute a "time reference status" which could be used as a basis for future monitoring
Hydrochemistry to delineate groundwater flow conditions in the Mogher Al Mer area (Damascus Basin, Southwestern Syria)
No full textInternational audienceThe hydrochemistry of groundwater from the Mogher Al Mer area, located in southwestern Syria, has been used as a tool to identify and assess the hydrogeological systems and associated conditions. In this arid region of Syria, groundwater is considered as the main source of water supply for both drinking and irrigation purposes. The detailed description of hydrogeochemical conditions, including major ions, physico-chemical and in situ field parameters, has underlined the very complex variability of the stratigraphic sequences and hence the numerous hydrogeological units within the study area. On the one hand, groundwater chemical signature is found to be mainly controlled by the water–rock interaction processes in the mountainous western part of the study area. On the other hand, anthropogenic influences are observed in the eastern plain. In terms of recharge mechanisms, the region can be considered as a part of a main intermediate or even regional flow system instead of a local one
Prediction of copper and chromium concentrations in bean leaves based on an artificial neural network model
No full textInternational audienceThe assessment of copper and chromium concentrations in plants requires the quantification of a large number of soil factors that affect their potential availability and subsequent toxicity and a mathematical model that predicts their relative concentrations in plants. While many soil characteristics have been implicated as altering copper and chromium availability to plants in soil, accurate, rapid and simple predictive models of metal concentrations are still lacking for soil and plant analysis. In the current study, an artificial neural network model was developed and applied to predict the exposure of bean leaves (BL) to high concentrations of copper and chromium versus some selected soil properties (pH, soil electrical conductivity and dissolved organic carbon). A series of measurements was performed on soil samples to assess the variation of copper and chromium concentrations in BL versus the soil inputs. The performance of the artificial neural network model was then evaluated using a test data set and applied to predict the exposure of the BL to the metal concentration versus the soil inputs. Correlation coefficients of 0.99981 and 0.9979 for Cu and 0.99979 and 0.9975 for Cr between the measured and artificial neural networks predicted values were found, respectively, during the testing and validation procedures. Results showed that the artificial neural network model can be successfully applied to the rapid and accurate prediction of copper and chromium concentrations in B
Aqueous solubility (in the range between 298.15 and 338.15 K), vapor pressures (in the range between 10−5 and 80 Pa) and Henry's law constant of 1,2,3,4-dibenzanthracene and 1,2,5,6-dibenzanthracene
No full textInternational audienceAqueous solubility and vapor pressures of 1,2,3,4-dibenzanthracene and 1,2,5,6-dibenzanthracene were determined using dynamic saturation methods. For the two isomers, aqueous solubility is in the range between 10−10 and 10−2 in molar fraction corresponding to temperature between 298.15 and 338.15 K. Vapor pressures of the pure solutes range from 10−5 to 80 Pa. Prior to the study of the two dibenzanthracenes and in order to check the experimental procedures, solubility of fluoranthene (between 298 and 338 K) and vapor pressures of phenanthrene and fluoranthene (between 300 and 470 K) were measured. From aqueous solubility data coupled with the vapor pressures of the pure solutes, partition coefficient air-water, KAW, and Henry's constant, KH, of environmental relevance were calculated
Characterization of the time dynamics of monthly satellite snow cover data on Mountain Chains in Lebanon
No full textInternational audienc
La pauvreté à Djibouti : une analyse multidimensionnelle
No full textL'éradication de l'extrême pauvreté, un des piliers des objectifs millénaires de développement (OMD) est loin d'être atteint actuellement. Le défi majeur étant de construire un cadre économique multidimensionnelle tels que la santé, l'éducation, les conditions de vie etc. Cet article vise à effectuer une analyse de la pauvreté en plusieurs dimensions sur Djibouti. Il a le mérite d'être le premier travail dans ce pays. L'analyse unidimensionnelle (analyse traditionnelle) de la pauvreté suppose que seul le revenu est une bonne prédiction du statut pauvre ou non pauvre de l'individu. Une telle analyse est donc insuffisante parce qu'elle ne permet pas d'étudier la pauvreté dans sa globalité. L'analyse multidimensionnelle, en se basant sur la méthodologie d'Alkire et Foster (2007) nous a paru indispensable dans la mesure où elle tient compte non seulement le revenu, mais d'autres facteurs socio-économiques comme la santé, l'éducation, les conditions de vie ... . Et dans ce sens elle permet de mieux appréhender la notion de pauvreté dans son ensemble. Les analyses statistiques multidimensionnelles ont été effectuées sur les données de la troisième enquête Djiboutienne auprès des ménages pour les indicateurs sociaux (EDAM3-IS) réalisée en avril 2012. Les résultats fournis nous ont permis de construire un indice composite de la pauvreté multidimensionnelle à Djibouti, puis une ventilation par dimension et par milieu de résidence a été opéré pour montrer la disparité de la pauvreté multidimensionnelle, qui est plus accentuée dans les zones rurales et touche plus particulièrement les ménages souffrant de privation de l'accès aux service de santé et dont le chef de ménage n'est pas alphabétisé et qui sont en temps en manque des certains bien matériels facilitant les conditions de vie
Révision de la "Falaise de Blanche" (Crétacé inférieur) au Liban et définition de l'Étage Régional Jezzinien
No full textInternational audienceThe "Falaise de Blanche" is a prominent cliff, consisting mostly of Lower Cretaceous limestones that extends as linear outcrops over most of the Lebanese territory and provides geologists a remarkable reference for stratigraphic studies. However, until now, this unit was lacking a clear definition. We introduce herein the Jezzinian Regional Stage, the type-locality of which is at Jezzine. It equates as an unconformity-bounded unit and, per definition, it is framed by two discontinuities. Because we identified an additional, median sequence-boundary, poorly-expressed in the type-section but better at Aazour, only 4.5 km westward of Jezzine, the new regional stage implicitly spans two sequences. The lithostratigraphic framework being properly redefined, we were able to investigate time-constrained micropaleontological assemblages, consisting mostly of benthic foraminifers and calcareous algae. Typically Southern Tethysian, these assemblages contribute to high-resolution, holostratigraphic correlations with the Persian Gulf area, on the eastern part of the Arabian Plate. The Jezzinian interval correlates with the upper part of the Kharaibian Regional Stage (also known as "Thamama II" reservoir unit in the oil industry). In turn, the Jezzinian is indirectly correlated with the Northern Tethysian Urgonian stratigraphic units where it corresponds to a rather short interval encompassing the standard Barremian - Bedoulian stage boundary. Locally the upper discontinuity is associated to a significant intra-Bedoulian hiatus. The macrofossil assemblages found in the Jezzinian (echinids) and above it (ammonites) support, or at least do not contradict, our micropaleontological dating.Les calcaires du Crétacé inférieur de la "Falaise de Blanche" affleurent sur une grande partie du territoire libanais. Ils apparaissent dans le paysage sous forme d'escarpements linéaires saillants constituant autant de points d'ancrage remarquables pour tout recalage stratigraphique. Toutefois, jusqu'à très récemment, cette unité était piètrement caractérisée : il lui manquait notamment une définition rigoureuse. Nous introduisons ici l'Étage Régional Jezzinien, dont la localité-type est sise à Jezzine. Il s'agit d'une unité stratigraphique particulière, aussi appelée U.B.U. (pour "unconformity-bounded unit"), une unité qui, par définition, est encadrée par deux discontinuités. Parce que nous avons identifié une limite de séquence supplémentaire, en position médiane, peu exprimée dans la section-type, mais beaucoup mieux à Aazour, à 4,5 km à peine à l'ouest de Jezzine, le nouvel étage régional devrait implicitement couvrir deux séquences. Le canevas lithostratigraphique étant clairement redéfini, nous avons pu étudier les associations micropaléontologiques, constituées essentiellement de foraminifères benthiques et d'algues calcaires, associations dorénavant relativement bien contraintes du point de vue de leur âge. Typiquement sud-téthysiennes, elles facilitent les corrélations holostratigraphiques à haute résolution avec la région du Golfe persique, sur le côté oriental de la Plaque arabique. L'intervalle Jezzinien correspond ainsi à la partie supérieure de l'Étage Régional Kharaibien (aussi connu comme unité réservoir "Thamama II" dans l'industrie pétrolière). À son tour, le Jezzinien est indirectement corrélé avec les unités stratigraphiques urgoniennes nord-téthysiennes où il correspond à un intervalle relativement court comprenant la limite des étages standards (internationaux) Barrémien et Bédoulien. Localement la discontinuité sommitale est associée à un hiatus intra-Bédoulien significatif. Les associations macropaléontologiques reconnues dans le Jezzinien (échinides) et au-dessus de cette unité (ammonites) viennent à l'appui de notre datation micropaléontologique ou tout au moins ne la contredisent pas
A dynamic measurement of a disc chipper cutting forces
No full textInternational audienceNowadays wood chips produced from raw material of inferior quality are mainly used to feed domestic and industrial boilers. For this use, a good chip size distribution and low manufacturing energy consumption are required. Cutting forces are still inaccurately measured during the wood chipping process, which implies the use of oversized chippers' motors. A test bench for chipping wood under reasonably realistic conditions of industrial production is improved by adding an indirect force measurement system with high bandwidth of 3 KHz. The dynamic experimentations give the data needed to compute the curve presenting the vertical component of the cutting force, which is composed of three sections; the first one presents the values of the impact force; the second one is relatively straight and it refers to shear stress in wood; the third section corresponds to the period between two crosscuts.</div