La enseñanza de Urbanismo 1 A en el 2021

El 2021 será un año recordado en la historia de la Cátedra de Urbanismo 1 A. Por un lado representa la celebración de los 15 años de la Cátedra de Urbanismo 1 A desde su conformación en 2006. Durante este tiempo la Cátedra ha consolidado el proceso de enseñanza aprendizaje de la disciplina urbanismo para arquitectos, poniendo énfasis en dos instrumentos fundamentales: el plan de un sector urbano y el proyecto urbano. Para ello aborda la complejidad de la dimensión físico espacial desde tres enfoques complementarios el físico funcional, el morfológico perceptual y el socio ambiental. Esta mirada transversal e integradora del fenómeno físico urbano, propia del nivel IV y del plan de estudios de la carrera, permite comprender la complejidad del fenómeno urbano actual, y las implicancias del desarrollo sostenible, no solo abordando los enfoques tradicionales sino incorporando la urgencia de los problemas ambientales actuales y el protagonismo de las ciudades en su determinación. Por otro lado, el 2021 cierre un período de dos años (2020-2021) donde el proceso pedagógico estuvo afectado, con algunas excepciones, al confinamiento obligatorio, lo que llevó a adaptar la enseñanza presencial a una modalidad virtual sincrónica, y que transcurrido ese tiempo, nos permite re adaptarnos, apoyándonos en lo mejor de ambas formas, presencial y virtual.Fil: Martinez, Monica. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Peralta, Carolina. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Scarabello, Juan Pablo. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Gordillo, Natacha. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Schiavoni, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Sesma, Gustavo Andrés. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Saggiorato, Sabrina. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Arreguéz, Facundo. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Leithold Berni, Bernardo. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Domizzi, Fabiola. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Medic, Marcelo. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; ArgentinaFil: Silveyra, Ana. Universidad Nacional de Córdoba. Facultad de Arquitectura, Urbanismo y Diseño; Argentin

Determination of residual stresses around blisters in Zr-2.5%Nb pressure tubes

We have used synchrotron X-ray diffraction experiments to measure the strain field introduced by a hydride blister grown on a section of a pressure tube from a CANDU nuclear reactor. After charging the tube section with a homogeneous hydrogen concentration of 300 wt ppm, the blister was produced by creating a small cold spot on its surface (similar to 200 degrees C), while the bulk was kept at a temperature of 338 degrees C over a period of 1008 h. The blister studied here is ellipsoidal in shape, with its long axis along the tube axial direction. The experiments were performed on the wiggler beam line ID15 at the European Synchrotron Radiation Facility (ESRF) using a polychromatic beam of high-energy X-rays (60 to 300 keV). Unlike conventional X-ray diffraction, in this mode the scattering angle is fixed and the diffracted beam is discriminated on the basis of the photon energy. The results show that the blister is composed by two crystallographic phases (delta-ZrH and alpha-Zr), with volume fractions varying with position. The maximum stresses appear at the blister-matrix interfaces. Near the tube outer surface, we found large compressive stresses of (-450 +/- 90) MPa along the blister long axis, and tensile stresses (+320 +/- 90) MPa along the tube hoop direction. The main uncertainty in these stresses results from the uncertainty in the elastic constants of the hydride phase. Large strains and broad peaks were observed for this phase, which were explained by a rather low Young's modulus (35 GPa) for the hydride. The results are compared with finite element simulations found in the literature. (C) 2009 International Centre for Diffraction Data. [DOI: 10.1154/1.3139056

Elastic strain tensor of zirconium hydrides in Zr2.5%Nb pressure tubes by synchrotron X-ray diffraction

Zirconium alloys are used in fuel cladding and structural components of nuclear power plants. Hydrogen enters the Zr matrix during plant operation and precipitates as hydride particles that degrade the mechanical properties of the alloy, limiting service life. Knowledge of the stress state within hydride precipitates is important to understand stress-induced degradation mechanisms such as delayed hydride cracking, but no direct quantification has yet been reported in the literature. Here, measurements are reported of the average elastic strain tensor within zirconium hydride precipitates in Zr2.5%Nb pressure tube material from CANDU power plants. Complete intensity and strain pole figures for the hydride were obtained by synchrotron X-ray diffraction experiments on specimens with hydrogen contents ranging from 100 wt p.p.m. hydrogen to nearly 100% -hydride. Zirconium hydride precipitates by a process involving a martensitic transformation, with two hydride variants possible from a single -Zr grain. A synthetic model of the hydride crystallographic texture allowed the interpretation of the measured strain pole figures and quantification of the elastic strain tensor for both texture components. It was found that the two variants appear in nearly equal proportion but with different stress states, differing in the sign of the shear strain components (3000 m"). This difference is possibly associated with the shear movement of Zr atoms during the phase transformation. This suggests that hydride clusters are composed of stacks of smaller hydrides in alternating hydride variants. Stresses were estimated from a set of rather uncertain hydride elastic constants. Overall, both variants showed compressive strains along the tube axial direction (5000 m"). For low hydrogen concentrations, the hydrides’ stress tensor is dominated by compressive stresses of 300 MPa along the axial direction, probably caused by the elongated morphology of hydride clusters along this direction, and variant-dependent shear stresses of 100 MPa, probably from the shear movement of the Zr sublattice involved in the phase transformation.Fil: Vicente Alvarez, Miguel Angel. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Santisteban, Javier Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Domizzi, Gladys. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Okasinskic, John. Argonne National Laboratory; Estados UnidosFil: Almerc, Jonathan. Argonne National Laboratory; Estados Unido

Self-inflicted fracture of expanding surface precipitates

This work concerns spontaneous fracture of growing brittle precipitates in an elastic plastic matrix. The mass of the precipitate is increasing as more transformed matrix material is added to it. Under stress-free conditions, the new phase occupies a larger volume than the original matrix material. Just outside the expanding precipitate, the matrix undergoes stretching beyond the elastic limit. The influence of the elastic plastic material behaviour is studied. A phase field model that keeps track of the phase composition is used. Both cases with a crack and without a crack are included. The growth histories from microscopic to macroscopic precipitate sizes are followed. Growth of the precipitate is very slow and quasi-static mechanical equilibrium is assumed at all time. The result is compared with observations of hydride blisters that are formed on surfaces of zirconium alloys. The numerical model is qualified against a derived exact solution for a cylindrical precipitate without a crack. The numerical result predicts a position of the growing crack that is confirmed by the observations. Also, the predicted length of the crack is in fair agreement with the experimental observations. The depth of the blister is slightly larger than what is found at the experiments. Also, it is found that the incorporated transformed phase rejects the compression, which creates an increasing tensile stress in the inner part of the precipitate

An efficient pattern-based approach for workflow supporting large-scale science: The DagOnStar experience

Workflow engines are commonly used to orchestrate large-scale scientific computations such as, but not limited to weather, climate, natural disasters, food safety, and territorial management. However, to implement, manage, and execute real-world scientific applications in the form of workflows on multiple infrastructures (servers, clusters, cloud) remains a challenge. In this paper, we present DagOnStar (Directed Acyclic Graph OnAnything), a lightweight Python library implementing a workflow paradigm based on parallel patterns that can be executed on any combination of local machines, on-premise high performance computing clusters, containers, and cloud-based virtual infrastructures. DagOnStar is designed to minimize data movement to reduce the application storage footprint. A case study based on a real-world application is explored to illustrate the use of this novel workflow engine: a containerized weather data collection application deployed on multiple infrastructures. An experimental comparison with other state-of-the-art workflow engines shows that DagOnStar can run workflows on multiple types of infrastructure with an improvement of 50.19% in run time when using a parallel pattern with eight task-level workers