14 research outputs found
thin films up to 550 °C
No full textThe temperature dependent thermal conductivity of In–Sb–Te thin films has been measured by modulated photothermal radiometry in the 20–550 °C range for samples with different Te content. Significant changes with temperature are observed and ascribed to a sequence of structural transformations on the basis of in-situ Raman spectra. The data suggest that the as-deposited material consisting of a mixture of polycrystalline InSb0.8Te0.2and amorphous Te first undergoes a progressive crystallization of the amorphous part, mostly above 300 °C. Further increase in temperature above 460 °C leads, for higher Te content in the alloy, to the formation of crystalline In3SbTe2, intertwined with a less conductive compound, possibly InTe and/or InSb. Upon cooling to room temperature, the initial polycrystalline InSb0.8Te0.2phase is mostly recovered along with other compounds, with a slightly higher thermal conductivity than that of the as deposited material. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim
A Study of the Behavior of Implicit Pressure Explicit Saturation (IMPES) Schedules for Two-phase Flow in Dynamic Pore Network Models
No full textInternational audienceWe focus on the numerical difficulties that typify implicit pressure explicit saturation (IMPES) schedules in dynamic "ball-and-stick" pore network models for two-phase flow. We show that a time stepping procedure based on a prescribed maximum variation of the local capillary pressure rather than on a (usual) maximum variation of the local saturation along with the addition in the solution algorithm of suitable "flow constraints" (in Koplik and Lasseter, Soc. Pet. Eng. J. 25(1):89-100, 1985) provide more stability and a significant run time speed up. In particular, the slow convergence and the oscillatory behavior that typify IMPES schemes at low Ca values due to capillary pinning are efficiently suppressed
Numerical Investigation of the Coupling between the Microgeometry and the Permeability Tensor of Natural Porous Media through the Volume Averaging Theory
No full textCharacterization of various stages of calcitization in Porites sp corals from uplifted reefs - Case studies from New Caledonia, Vanuatu, and Futuna (South-West Pacific)
No full textThis study focuses on the processes of calcitization under meteoric conditions based on observations and analyses of a series of subaerial fossil corals of the genus Pontes collected from emerged Holocene and Pleistocene reefs in the Pacific Ocean. We can establish two types of low-magnesian calcite (LMC) precipitates according to their textural characteristics after their transformation from the initial aragonitic skeleton to the calcitized corals. In the first variety (LMCI), the calcite contains remnants of the original exoskeleton structure (in situ insoluble organic tissues. pieces of aragonite needles) while in the second variety (LMC2) - filling the primary inter-skeletal macro-pores - such relicts are not present. Such textural segregation is faithfully reflected in the elemental data on some parts of calcitized corals. LMC1 is characterized by Mg2+, Sr2+, and Mn2+ compositions inherited from the aragonite precursor, indicating a formation in a semi-closed infra-skeleton diagenetic environment in disequilibrium with the meteoric bulk aquifer water. LMC2 has a chemistry indicative of equilibrium with ambient bulk meteoric water. These chemical characteristics can be likened to a two-fold mechanism: a fine-scale process - neomorphism typified by the concomitant dissolution of intra-fabric aragonite and re-precipitation of the LMCI resulting from the 'biogenic' skeleton and marine waters, followed by the cementation of the inter-fabric macro-voids by an allochthonous subaerial and meteoric LMC2. In the other parts of calcitized corals, LMCI and LMC2 have similar trace element contents in Mgt(2+) and Sr2+. The chemical data are consistent with formation by partial skeletal dissolution followed eventually by cementation of primary voids (LMC2) and secondary voids (LMC1) by calcite in equilibrium with meteoric bulk aquifer water. These two mechanisms of the calcitization of skeletal aragonite mainly differ in the space and time length-scales of the intervening transport step, and are commonly found juxtaposed in the same thin section. Taking into account such a heterogeneity is a real challenge for the development of predictive models assessing the effects of diagenetic products on paleoclimatic reconstructions
La relación del coaching en el desempeño laboral de los colaboradores del área de créditos de la Cooperativa de Ahorro y Crédito León XIII en la provincia de Virú- 2017
No full textLa presente investigación tuvo como propósito, determinar la relación que se dio, al realizar
Coaching en el desempeño laboral de los colaboradores del área de créditos de la Cooperativa
De Ahorro y Crédito León XIII de la ciudad de Virú en el año 2017.
En el primer capítulo, se determinó la realidad problemática, la formulación del problema, la
justificación, limitaciones y los objetivos que se pretenden alcanzar con el desarrollo de esta
investigación.
En el segundo capítulo, concerniente al marco teórico, se encuentran las conceptualizaciones del
Coaching y el desempeño laboral, lo que sirvió como sustento para elaborar nuestros indicadores.
En el tercer capítulo, se realiza la formulación de la hipótesis, así como la Operacionalización de
las variables dependiente e independiente.
En el cuarto capítulo se hace referencia al tipo de diseño de investigación, la unidad de estudio, la
población y la muestra además de presentar las técnicas e instrumentos de recolección y análisis
de datos.
En quinto capítulo se presenta el desarrollo de la investigación, en el sexto capítulo se muestra los
resultados de la investigación, en el séptimo y último capítulo, se presenta la discusión.
Finalmente se presenta las conclusiones obtenidas, recomendaciones, referencias y anexos.The purpose of this research was to determine the relation that was given when performing
Coaching in the work performance of the credit area employees of the Leon XIII Savings and Credit
Cooperative in the city of Virú in the year 2017.
In the first chapter, the problematic reality, the formulation of the problem, the justification,
limitations and the objectives that are intended to be reached with the development of this research
were determined.
In the second chapter, concerning the theoretical framework, are the conceptualizations of
Coaching and work performance, which served as a basis for developing our indicators.
In the third chapter, the formulation of the hypothesis is carried out, as well as the
Operationalization of the dependent and independent variables.
In the fourth chapter, reference is made to the type of research design, the study unit, the
population and the sample, in addition to presenting the techniques and instruments for collecting
and analyzing data.
In the fifth chapter the development of the research is presented, in the sixth chapter the results of
the investigation are shown, in the seventh and last chapter, the discussion is presented.
Finally, the obtained conclusions, recommendations, references and annexes are presented
Characterization and valorization of lateritic materials used in road construction in Niger
No full textLes latérites sont les sols les plus utilisés dans les travaux de génie civil, plus particulièrement en construction routière dans la plupart des pays de la zone intertropicale. Ce sont des sols résiduels ou détritiques provenant de l’altération des roches préexistantes. Ces sols contiennent en quantité appréciable des oxydes de fer et d’aluminium, de la kaolinite et de la silice, mais de faibles quantités d’oxydes de titane, de manganèse, de magnésium, …, etc. La grande diversité des composés chimiques des latérites rend leur caractérisation malaisée. En outre, les documents normatifs et les guides techniques utilisés pour le dimensionnement des chaussées en Afrique subsaharienne pour la plupart inadaptés, ne prennent pas en compte la spécificité des conditions climatiques et environnementales des formations latéritiques dans les projets routiers. Une caractérisation interdisciplinaire de ces sols avec la prise en compte des facteurs intervenant dans le processus de latéritisation permettrait de déterminer des propriétés plus précises, plus pertinentes et beaucoup plus représentatives. Ce travail a pour vocation la caractérisation et la détermination de l’aptitude des sols latéritiques du sud-ouest du Niger. La zone concernée par l’étude comporte sept gisements latéritiques aux contextes géologiques forts différents les uns des autres. Notre étude, basée sur diverses approches a permis de déterminer les propriétés géotechniques et mécaniques des sols d’une part et les propriétés chimiques et minéralogiques d’autre part. À l’issue de l’étude, deux catégories de sols sont à distinguer : [1] les sols de bonne portance : d’indice CBR de l’ordre de 100 contiennent en moyenne une teneur en fines n’excédant pas 12% et un indice de plasticité inférieur à 15. Pour ces sols, la portance dépend beaucoup de la taille des particules. Ces derniers ont une résistance élevée au cisaillement et un angle de frottement interne effectif φ’ de l’ordre de 40° ainsi qu’une cohésion effective c’ supérieure à 10 kPa. Leur comportement est dilatant au cours du cisaillement. Ils présentent de faibles valeurs en indice de vide et en perméabilité. De même, leur amplitude de tassement est faible. La bonne portance de ces sols se justifie principalement par leur teneur appréciable en oxydes de fer. L’attaque de la matrice fine par ces derniers se fait de manière diffuse ou par concrétionnement sous forme de cercles d’oolithes et de pisolithes ovoïdes tangents. [2] les sols de faible portance : la fraction fine et l’indice de plasticité sont élevés, respectivement de l’ordre de 25 et 30. La portance est de l’ordre de 30, l’angle de frottement interne inférieur à 30° et la cohésion inférieure à 5 kPa. Ces sols résistent faiblement au cisaillement et leur comportement est contractant, c’est-à-dire celui d’un sable lâche. Ils sont plus compressibles, encore moins perméables avec un coefficient de gonflement élevé. La faible portance de ces sols est imputable à leur faible teneur en oxydes de fer, ainsi que le mode d’attaque qui se fait de manière isolée.L’amélioration des sols présentant une faible portance a été expérimentée en y rajoutant séparément une certaine teneur en liant hydraulique (ciment), en chaux (CaO) et en nodules latéritiques. Les analyses minéralogiques et chimiques ont montré que l’ajout des produits a conduit à une modification texturale et a favorisé la mise en place de composés chimiques néo-synthétisés ayant pour rôle principal de renforcer les liaisons entre les éléments minéraux contenus dans les échantillons de sol latéritique. Dans la plupart des cas, les échantillons améliorés ont présenté une bonne portance validant ainsi leur aptitude en construction routière.Laterites are the most commonly used soils in civil engineering works, particularly in road construction in most countries of intertropical region. These are residual or detrital soils resulting from the alteration of pre-existing rocks. These soils contain a considerable quantity of iron and aluminum oxides, kaolinite and silica, but small quantities of titanium oxides, manganese, magnesium, etc. The large diversity of the chemical compounds of laterites makes their characterization difficult. Moreover, specification documents and technical guides used for road design in sub-saharan Africa, most of them unsuitable, do not take into account the specificity of climatic and environmental conditions of laterite formations in road projects. An interdisciplinary characterization of these soils, taking into account the factors involved in the lateritization process, should make it possible to be determined more precisely. It’s also the best way to get more relevant and much more representative properties. The aim of this work is to characterize and determine the lateritic soils suitability of southwestern Niger in road construction. The area covered by the study consists of seven lateritic deposits with strong geological different contexts from one to another. Our study, based on various approaches, made it possible to determine the geotechnical and mechanical properties of the soils on the one hand and the chemical and mineralogical properties on the other hand. At the end of the study, two categories of soils are to be distinguished: [1] soils with good bearing capacity : CBR of around 100 contain average fines content not exceeding 12% and a plasticity index less than 15. For these soils, the bearing capcity depends very much on the size of the particles. They have a high shear strength, an effective internal friction angle φ' of the order of 40° and an effective cohesion c' greater than 10 kPa. Their behavior is dilatant during shear. They have low values in void ratio and in index permeability. Similarly, their amplitude of settlement is low. The good bearing capacity of these soils is mainly justified by their appreciable iron oxides content. The attack of the microstructure by the latter is done in diffuse way or by concretionary circles of oolites. [2] the soils of low bearing capacity : the fine fraction and the plasticity index are high respectively of the order of 25 and 30. The bearing capacity is around 30, the internal friction angle is less than 30° and the cohesion less than 5 kPa. These soils are weak to the shear and their behavior is contracting (loose sand behavior). They are more compressible and less permeable with a high swelling coefficient. The low bearing capacity of these soils is attributable to their low iron oxide content and to the mode of attack which is carried out in isolated way.The improvement of soils with low bearing capacity has been tested separately by adding a certain amount of hydraulic binder (cement), lime (CaO) and lateritic nodules. Mineralogical and chemical analyzes showed that the addition of the products led to a textural modification and favored the production of neo-synthesized chemical compounds whose main role was to strengthen the links between the mineral elements contained in the lateritic samples. In most cases, the improved samples showed good bearing capacity and validated their road pavement suitability
Deformation bands and alteration in porous glass-rich volcaniclastics: Insights from Milos, Greece
No full textInternational audienceDeformation bands in porous volcaniclastics are little studied structural heterogeneities despite their relevance for constraining the modalities of deformation development and related fluid-rock interactions in volcanic areas.We document a dense network of normal-sense Deformation Bands (Normal-sense Compactional Shear Bands (NCSBs) affecting upper Pliocene felsic glassy tuffites in Milos, Greece. NCSBs probably formed between 300 and 500 m of burial depth, in response to NE-SW directed extension which is related to volcanic rift development in the area. They accommodate mm-to m-shear-offsets, trend either N105 ± 10° or N070 ± 10°, and show mutual cross-cutting relations. The NCSB fault rock is made of ultracataclasite in which the cataclastic mechanisms have affected both the mineral fraction and the volcanic glass. Minerals are fractured along their cleavages whereas pumices are interestingly fractured along their vesicles.The development of chemical alteration (dissolution and cementation) essentially into the ultracataclasite is expressed through glass-hosted corrosion gulfs and smectites filling the intergranular porosity. These observations support that NCSBs preferentially retained water, have been the seat of greater fluid flow, and are the locus of ongoing phyllosilicate self-sealing in the vadose zone. A significant decrease (up to one order of magnitude) in porosity is measured within the studied NCSB
Modeling physical properties of sandstone reservoirs by blending 2D image analysis data with 3D capillary pressure data
No full textCharacterization and valorization of lateritic materials used in road construction in Niger
No full textLes latérites sont les sols les plus utilisés dans les travaux de génie civil, plus particulièrement en construction routière dans la plupart des pays de la zone intertropicale. Ce sont des sols résiduels ou détritiques provenant de l’altération des roches préexistantes. Ces sols contiennent en quantité appréciable des oxydes de fer et d’aluminium, de la kaolinite et de la silice, mais de faibles quantités d’oxydes de titane, de manganèse, de magnésium, …, etc. La grande diversité des composés chimiques des latérites rend leur caractérisation malaisée. En outre, les documents normatifs et les guides techniques utilisés pour le dimensionnement des chaussées en Afrique subsaharienne pour la plupart inadaptés, ne prennent pas en compte la spécificité des conditions climatiques et environnementales des formations latéritiques dans les projets routiers. Une caractérisation interdisciplinaire de ces sols avec la prise en compte des facteurs intervenant dans le processus de latéritisation permettrait de déterminer des propriétés plus précises, plus pertinentes et beaucoup plus représentatives. Ce travail a pour vocation la caractérisation et la détermination de l’aptitude des sols latéritiques du sud-ouest du Niger. La zone concernée par l’étude comporte sept gisements latéritiques aux contextes géologiques forts différents les uns des autres. Notre étude, basée sur diverses approches a permis de déterminer les propriétés géotechniques et mécaniques des sols d’une part et les propriétés chimiques et minéralogiques d’autre part. À l’issue de l’étude, deux catégories de sols sont à distinguer : [1] les sols de bonne portance : d’indice CBR de l’ordre de 100 contiennent en moyenne une teneur en fines n’excédant pas 12% et un indice de plasticité inférieur à 15. Pour ces sols, la portance dépend beaucoup de la taille des particules. Ces derniers ont une résistance élevée au cisaillement et un angle de frottement interne effectif φ’ de l’ordre de 40° ainsi qu’une cohésion effective c’ supérieure à 10 kPa. Leur comportement est dilatant au cours du cisaillement. Ils présentent de faibles valeurs en indice de vide et en perméabilité. De même, leur amplitude de tassement est faible. La bonne portance de ces sols se justifie principalement par leur teneur appréciable en oxydes de fer. L’attaque de la matrice fine par ces derniers se fait de manière diffuse ou par concrétionnement sous forme de cercles d’oolithes et de pisolithes ovoïdes tangents. [2] les sols de faible portance : la fraction fine et l’indice de plasticité sont élevés, respectivement de l’ordre de 25 et 30. La portance est de l’ordre de 30, l’angle de frottement interne inférieur à 30° et la cohésion inférieure à 5 kPa. Ces sols résistent faiblement au cisaillement et leur comportement est contractant, c’est-à-dire celui d’un sable lâche. Ils sont plus compressibles, encore moins perméables avec un coefficient de gonflement élevé. La faible portance de ces sols est imputable à leur faible teneur en oxydes de fer, ainsi que le mode d’attaque qui se fait de manière isolée.L’amélioration des sols présentant une faible portance a été expérimentée en y rajoutant séparément une certaine teneur en liant hydraulique (ciment), en chaux (CaO) et en nodules latéritiques. Les analyses minéralogiques et chimiques ont montré que l’ajout des produits a conduit à une modification texturale et a favorisé la mise en place de composés chimiques néo-synthétisés ayant pour rôle principal de renforcer les liaisons entre les éléments minéraux contenus dans les échantillons de sol latéritique. Dans la plupart des cas, les échantillons améliorés ont présenté une bonne portance validant ainsi leur aptitude en construction routière.Laterites are the most commonly used soils in civil engineering works, particularly in road construction in most countries of intertropical region. These are residual or detrital soils resulting from the alteration of pre-existing rocks. These soils contain a considerable quantity of iron and aluminum oxides, kaolinite and silica, but small quantities of titanium oxides, manganese, magnesium, etc. The large diversity of the chemical compounds of laterites makes their characterization difficult. Moreover, specification documents and technical guides used for road design in sub-saharan Africa, most of them unsuitable, do not take into account the specificity of climatic and environmental conditions of laterite formations in road projects. An interdisciplinary characterization of these soils, taking into account the factors involved in the lateritization process, should make it possible to be determined more precisely. It’s also the best way to get more relevant and much more representative properties. The aim of this work is to characterize and determine the lateritic soils suitability of southwestern Niger in road construction. The area covered by the study consists of seven lateritic deposits with strong geological different contexts from one to another. Our study, based on various approaches, made it possible to determine the geotechnical and mechanical properties of the soils on the one hand and the chemical and mineralogical properties on the other hand. At the end of the study, two categories of soils are to be distinguished: [1] soils with good bearing capacity : CBR of around 100 contain average fines content not exceeding 12% and a plasticity index less than 15. For these soils, the bearing capcity depends very much on the size of the particles. They have a high shear strength, an effective internal friction angle φ' of the order of 40° and an effective cohesion c' greater than 10 kPa. Their behavior is dilatant during shear. They have low values in void ratio and in index permeability. Similarly, their amplitude of settlement is low. The good bearing capacity of these soils is mainly justified by their appreciable iron oxides content. The attack of the microstructure by the latter is done in diffuse way or by concretionary circles of oolites. [2] the soils of low bearing capacity : the fine fraction and the plasticity index are high respectively of the order of 25 and 30. The bearing capacity is around 30, the internal friction angle is less than 30° and the cohesion less than 5 kPa. These soils are weak to the shear and their behavior is contracting (loose sand behavior). They are more compressible and less permeable with a high swelling coefficient. The low bearing capacity of these soils is attributable to their low iron oxide content and to the mode of attack which is carried out in isolated way.The improvement of soils with low bearing capacity has been tested separately by adding a certain amount of hydraulic binder (cement), lime (CaO) and lateritic nodules. Mineralogical and chemical analyzes showed that the addition of the products led to a textural modification and favored the production of neo-synthesized chemical compounds whose main role was to strengthen the links between the mineral elements contained in the lateritic samples. In most cases, the improved samples showed good bearing capacity and validated their road pavement suitability
