121 research outputs found

    Qualification Conditions for Calculus Rules of Coderivatives of Multivalued Mappings

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    AbstractThis paper establishes by a general approach a full calculus for the limiting Fréchet and the approximate coderivatives of multivalued mappings. This approach allows us to produce several new verifiable qualification conditions for such calculus rules

    A New Method for the Determination of Sucrose Concentration in a Pure and Impure System: Spectrophotometric Method

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    Analytical chemistry is a set of procedures and techniques used to identify and quantify the composition of a sample of material. It is also focused on improvements in experimental design and the creation of new measurement tools. Analytical chemistry has broad applications to forensics, medicine, science, and engineering. The objective of this study is to develop a new method of sucrose dosage using a spectrophotometry method in a pure and impure system (presence of glucose and fructose). The work performed shows the reliability of this method. A model linking sucrose solution absorbance and mass percentage of glucose and fructose has been developed using experimental design. The results obtained show that all the investigated factors (sucrose concentration, mass percentage of glucose, and mass percentage of fructose) have a positive effect on the absorbance. The effect of the interaction between glucose and fructose on the absorbance is very significant

    Mise en Ă©vidence d’un SĂ©nonien gypseux sous la sĂ©rie phosphatĂ©e du bassin des Ouled Abdoun: Un nouveau point de dĂ©part pour l’origine des zones dĂ©rangĂ©es dans les mines Ă  ciel ouvert de Khouribga, Maroc

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    In the Ouled Abdoun sedimentary basin (Morocco), the phosphatic series is composed of regular interbedded phosphatic and marly limestone layers. Exploitation of the phosphate in some deposits in this basin collides frequently with problems bound to the existence, in the phosphatic series, of disturbed areas (sterile bodies) qualified as derangements by the mining engineers of the Office Cherifian Phosphate Group (OCP). Their presence in the phosphatic layers causes two kinds of problems: (1) since the whole phosphatic sequence is overlain by a Quaternary cover, we do not know their volume proportion in the phosphatic layers, and therefore the reserves estimations can be wrong (2) they are generally hard, so they complicate the phosphate extraction. Indeed, in an area containing sterile bodies, boring grid may always be tightened and boreholes filled with dynamite. The required borehole tools and use of explosives are time consuming and therefore increase drastically the cost of phosphate extraction. Their localisation would permit the mining engineers to get around them during the exploitation. Several geophysical works have carried out in the achieved in Khouribga area to localize and delimit these sterile bodies. Electric resistitivy was established as a suitable geophysical parameter to map them, but the slowness and difficulty of data collection hinders the application of these geophysical methods to the whose phosphatic deposits area (about 25000 ha). Their application in all the Ouled Abdoun basin requires the comprehension of the origin of the sterile bodies, in order to specify their formation process and to predict consequently their spacial distribution in each phosphatic deposit. Our study concerns to sedimentological and diagenetic analysis of disturbed aereas and their immediate vicinity. It made it possible to identify for the first time the existence of an evaporitic series intensely karstified at the top of the Senonian, under the phosphatic series. The senonian karsts are undoubtedly at the origin of the derangements, which are defined as the collapsing phenomena at the base of underground cavities. These bodies have a polyphase structuring and a genesis that is the consequence of on several processes (fracturing, infiltration, dissolution, collapse). Their installation began from the end of Senonian, and continues up to the Quaternary.[fr] Dans le bassin sĂ©dimentaire des Ouled Abdoun (Maroc), la sĂ©rie phosphatĂ©e est formĂ©e d’une intercalation rĂ©guliĂšre de niveaux phosphatĂ©s et marno-calcaires sur environ 50m de puissance. Localement, cette rĂ©gularitĂ© est perturbĂ©e par la prĂ©sence frĂ©quente de structures communĂ©ment appelĂ©s «dĂ©rangements». Il s’agit de masses non stratifiĂ©es, stĂ©riles, qui perturbent et alourdissent les travaux d’exploitation des couches phosphatĂ©es. Les Ă©tudes gĂ©ophysiques expĂ©rimentales, rĂ©alisĂ©es dans les zones dĂ©rangĂ©es de la sĂ©rie phosphatĂ©e, ont dĂ©montrĂ© la possibilitĂ© de les cartographier sous couvertures Ă  l’échelle dĂ©camĂ©trique. Leur gĂ©nĂ©ralisation sur toute la superficie du bassin des Ouled Abdoun, nĂ©cessite une comprĂ©hension du phĂ©nomĂšne Ă  l’origine de ces structures. Notre Ă©tude concerne l’analyse sĂ©dimentologique et diagĂ©nĂ©tique des zones dĂ©rangĂ©es et de leur voisinage immĂ©diat. Elle a permis d’identifier pour la premiĂšre fois l’existence d’une sĂ©rie Ă©vaporitique intensĂ©ment karstifiĂ©e au sommet du SĂ©nonien, sous la sĂ©rie phosphatĂ©e. Les karsts sĂ©noniens sont incontestablement Ă  l’origine des dĂ©rangements ou fontis que l’on dĂ©fini comme Ă©tant des phĂ©nomĂšnes de collapses Ă  l’aplomb de cavitĂ©s souterraines. Ces fontis ont une structuration polyphasĂ©e et une genĂšse au dĂ©pend de plusieurs processus (fracturation, infiltration, dissolution, effondrement). Leur mise en place a dĂ©butĂ© dĂšs la fin du SĂ©nonien et s’est poursuivie jusqu’au quaternaire

    Identification of d -arabinan-degrading enzymes in mycobacteria

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    Bacterial cell growth and division require the coordinated action of enzymes that synthesize and degrade cell wall polymers. Here, we identify enzymes that cleave the D-arabinan core of arabinogalactan, an unusual component of the cell wall of Mycobacterium tuberculosis and other mycobacteria. We screened 14 human gut-derived Bacteroidetes for arabinogalactan-degrading activities and identified four families of glycoside hydrolases with activity against the D-arabinan or D-galactan components of arabinogalactan. Using one of these isolates with exo-D-galactofuranosidase activity, we generated enriched D-arabinan and used it to identify a strain of Dysgonomonas gadei as a D-arabinan degrader. This enabled the discovery of endo- and exo-acting enzymes that cleave D-arabinan, including members of the DUF2961 family (GH172) and a family of glycoside hydrolases (DUF4185/GH183) that display endo-D-arabinofuranase activity and are conserved in mycobacteria and other microbes. Mycobacterial genomes encode two conserved endo-D-arabinanases with different preferences for the D-arabinan-containing cell wall components arabinogalactan and lipoarabinomannan, suggesting they are important for cell wall modification and/or degradation. The discovery of these enzymes will support future studies into the structure and function of the mycobacterial cell wall

    Numerical simulations of the surface topography effect on the generated frictional heat distribution in brake systems

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    611-617<span style="font-size:11.0pt;font-family: " times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;letter-spacing:-.1pt;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">Several studies have investigated the influence of various parameters on temperature at the surface contact disc/pad car, such as the vehicle deceleration, vehicle weight, braking force, coefficient of friction and pressure distribution over the braking surface area. However, hardly any study has been reported on the effect of surface roughness on the temperature distribution. In this study, a 3D numerical model is developed in order to investigate the effect of surface roughness on temperature field at different sliding speeds. The simulation reveals that the temperature at the surface and along the disc thickness depends strongly on asperities interactions and mode of surface deformation. This investigation also shows the beneficial role of copper in brake pad. The generated frictional heat at the contact surface between the brake disc and pad decreases with increasing of amount of copper up to a percentage of 8%. Beyond this proportion, the temperatures reach a stable level.</span

    Radiality and semismoothness

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    We provide sufficient conditions for radiality and semismoothness. In general Banach spaces, we show that calmness ensures Dini-radiality as well as Dini-convexity of solution set to inequality systems. In finite dimensional spaces, we introduce the concept of Clarke-radiality and semismoothness of order m and show that each subanalytic set satisfies these properties. Similar properties are obtained for locally Lipschitzian subanalytic functions
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