Análisis de falla de la represa Marcacocha del distrito de Uco provincia de Huari-Ancash

Publicación a texto completo no autorizada por el autorEl documento digital no refiere asesorRealiza los cálculos para verificar la estabilidad de la represa Marcacocha y deslizamiento de la estructura bajo el método clásico y el criterio técnico P.E.T. (Presa Elemental Triangular). Para aumentar la estabilidad y seguridad de la estructura se plantea una alternativa de solución, un modelo de contrafuerte que cumplirá con los reglamentos establecidos en la construcción de represas.Trabajo de suficiencia profesiona

Structure and electrical properties in the K1/2Bi1/2TiO3-K1/2Bi1/2ZrO3 solid solution (KBT-KBZ)

International audienceThe present work is devoted to the study of the Zr 4þ /Ti 4 substitution in the K1/2Bi1/2Ti(1-x)ZrxO3 solid solution (x ¼ 0.0 to x ¼ 1.0), based upon the K1/2Bi1/2TiO3 (KBT) ferroelectric compound. The tetragonal distortion of KBT is suppressed by this substitution and leads to the cubic compound K1/2Bi1/2ZrO3 (KBZ). These results agree with the values of the ionic radii of the Zr 4þ and Ti 4 ions (rTi 4þ ¼ 0.605 A˚ and rZr 4þ ¼ 0.72 A˚ ). Close to KBT (x 0.05), the symmetry remains tetragonal. For higher values of x, the ''a'' lattice parameter (cubic indexing) follows Vegard's law, thus confirming the formation of a solid solution. The transformation from tetragonal to cubic proceeds via an intermediate pseudocubic symmetry (0.1 x < 0.5), for which the X-ray diffraction peaks present small broadening and asymmetry. For x 0.5 and up to the KBZ compound (a 4.158 A˚ ), the samples are cubic but some extra peaks are also observed, indicating the occurrence of a secondary phase. The microstructure shows fine-grained ceramic samples for the first range, while for the KBZ-rich range the grains are micrometer-sized and associated to very small grains of the secondary phase. Piezoelectricity is observed for the tetragonal and pseudocubic range, the substitution quickly reducing the piezoelectric properties. The measurement of the dielectric properties revealed close to KBT a dielectric anomaly probably associated to the tetragonal-cubic phase transition. For thepseudocubic and cubic range, a broad dielectric anomaly is observed around 300 8C, corresponding to a relaxor behavior

Magnetic resonance imaging biomarkers for chronic kidney disease: a position paper from the European Cooperation in Science and Technology Action PARENCHIMA

Functional renal magnetic resonance imaging (MRI) has seen a number of recent advances, and techniques are now available that can generate quantitative imaging biomarkers with the potential to improve the management of kidney disease. Such biomarkers are sensitive to changes in renal blood flow, tissue perfusion, oxygenation and microstructure (including inflammation and fibrosis), processes that are important in a range of renal diseases including chronic kidney disease. However, several challenges remain to move these techniques towards clinical adoption, from technical validation through biological and clinical validation, to demonstration of cost-effectiveness and regulatory qualification. To address these challenges, the European Cooperation in Science and Technology Action PARENCHIMA was initiated in early 2017. PARENCHIMA is a multidisciplinary pan-European network with an overarching aim of eliminating the main barriers to the broader evaluation, commercial exploitation and clinical use of renal MRI biomarkers. This position paper lays out PARENCHIMA’s vision on key clinical questions that MRI must address to become more widely used in patients with kidney disease, first within research settings and ultimately in clinical practice. We then present a series of practical recommendations to accelerate the study and translation of these techniques