Calculation of the orientation relationships of directionally solidified eutectic ceramics by a modified Coincidence of Reciprocal Lattice Points model (CRLP)

The Coincidence of Reciprocal Lattice Points (CRLP) method was used to predict, according to geometric considerations, the most favorable orientation relationships (ORs) between the component phases in a family of directionally solidified eutectic ceramics (DSEC) (NiO-YSZ, CoO-YSZ, NiO-CeO2, NiO-GDC, CoO-CeO2, and CoO-GDC) grown by the laser floating zone method. The ORs predicted by the CRLP model are consistent with those experimentally found in a previous work by means of Electron Backscatter Diffraction (EBSD). In this article, we also present a modification to the model with the aim of taking into account that the most stable ceramic-ceramic interfaces are usually formed between atomic planes with low Miller indices, due to their higher atomic density and bigger interplanar spacing. Thus, we introduce in the calculation of the overall coincidence volume a weighting factor which is a function of the interplanar spacing. This modified CRLP method has been applied to the aforementioned eutectic ceramics, and the results are presented and discussed in comparison with the traditional CRLP results and the experimental findings.This study was funded by the MAT2012-30763 project, which is financed by the Spanish Government (Ministerio de Economía y Competitividad) and the Feder program of the European Union.Peer Reviewe

A novel three-phase mixture approach for the numerical modeling of self-aerated flows

This work presents a novel theoretical/numerical model for the simulation of self-aerated flows under a Reynolds-Averaged Navier-Stokes (RANS) framework. The new formulation is based on a three-phase mixture approach composed of a continuous air phase, a bubble phase, and a continuous water phase. A mass transfer mechanism that does not depend on an entrainment function and does not require calibration accounts for the incorporation of air into the flow. A modification in the formulation of the Volume-of-Fluid algorithm (used to track the free surface) allows one to capture the increase in water depth due to the presence of bubbles. The proposed formulation recovers the traditional Volume-of-Fluid formulation for free surface flows in the absence of bubbles, allowing the model to represent simultaneously the aerated and not aerated regions of a flow. Governing equations for the mixture are derived from mass and momentum conservation equations for each phase, and a numerical algorithm that ensures the boundedness of the numerical solution is proposed. The model is tested and validated using four experimental cases: a degassing tank, a bubble plume, a plunging jet, and a stepped spillway, showing very satisfactory results. The new methodology provides a significant advance in the current capabilities for simulating self-aerated flows.Fil: Zabaleta, Federico. University of California at Davis; Estados UnidosFil: Marquez Damian, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; ArgentinaFil: Bombardelli, Fabián A.. University of California at Davis; Estados Unido

Centro histórico de Cartagena de Indias, Colombia: una visión y valoración desde lo bio ambiental y paisajístico.

El artículo destaca un aspecto a considerar en los procesos de análisis, diagnóstico e intervención en edificios y espacios urbanos patrimoniales referente al conocimiento y puesta en valor de los atributos bio ambientales y paisajísticos de edificaciones y espacio público del centro histórico2 de Cartagena de Indias, Colombia. En la actualidad, intervenciones mal realizadas buscando confort artificial, afectaron tanto la coherencia ambiental de edificaciones patrimoniales como la adaptación del espacio urbano a las condiciones climáticas del lugar, generando lo que hemos denominado “esterilización del paisaje”.3 Ante esta realidad, se hace necesario el análisis de los atributos, su comportamiento bio ambiental y los beneficios que ese aspecto genera en zonas patrimoniales, asumiendo que esta información es clave en la elaboración del Plan Especial de Manejo y Protección (pemp) del centro histórico de la ciudad que se estudia.This article illustrates an aspect to be taken into account in the processes of analysis, diagnosis and intervention in buildings and patrimonial urban spaces that has to do with the knowledge and value of the bio environmental and landscape attributes of buildings and public space in the historic center of Cartagena de Indias, Colombia. At present, badly performed interventions, seeking artificial comfort, affected both the environmental coherence of heritage buildings, and the adaptation of the urban space to the climatic conditions of the place; generating what we have called “landscape sterilization”. Faced with this reality, it is necessary to analyze attributes, their environmental behavior and the benefits that this generates in heritage zones, assuming that this information is key in the elaboration of the Special Plan for Management and Protection (mtps) of the historic center of the city under study.Universidad San Buenaventura de Cartagena, Colombia

Sound absorbing and insulating low-cost panels from end-of-life household materials for the development of vulnerable contexts in circular economy perspective

From a construction point of view, neighborhoods with residents living at or below the poverty threshold are characterized by low energy efficiency buildings, in which people live in acoustic discomfort with no viable options for home improvements, as they usually can not afford the materials and labor costs associated. An alternative to this is to use low-cost insulating elements made of non-conventional materials with acceptable acoustic properties. Given that household materials at their end-of-life (EoLHM) are free of costs and available also to the more disadvantaged population, they can be used to build acoustic panels for such contexts. This approach embraces several benefits since it reduces the amount of waste produced, the footprint deriving from the extraction of new raw materials and, by highlighting the potential of the EoLHM, discourages the abandonment of waste. In this paper, the acoustic properties of EoLHM, such as cardboard, egg-cartons, clothes, metal elements and combinations of them, are investigated by means of the impedance tube technique. The measured sound absorption coefficient and transmission loss have shown that EoLHM can be used for the realization of acoustic panels. However, since none of the analyzed materials shows absorbing and insulating properties at the same time, EoLHM must be wisely selected. This innovative approach supports the circular economy and the improvement for the living condition of low-income households

Insensibilizador de baixo custo para abate de frangos coloniais.

bitstream/item/31428/1/comunicado-204.pd

Meeting high precision requirements of additively manufactured components through hybrid manufacturing

A hybrid approach combining the laser powder bed fusion (LPBF) process and post-processing operations through 5-axis milling was employed to manufacture a Ti6Al4V aerospace component. From the design step, the requirements and needs in all the stages of the Hybrid Additive Manufacturing process were taken into account. A numerical simulation of distortions promoted by residual stresses during the additive process was employed to consider material allowance. The status of the as-built and post-processed component was analysed through scanning and CMM inspection and roughness measurements. The 3D scanned model of the as-built LPBF-ed component was used to understand the distortion behaviour of the component and compared to the numerical simulation. Finally, 5-axis milling operations were conducted in some critical surfaces in order to improve surface quality and dimensional accuracy of the as-built com- ponent. The inspection of the as-built and post-processed component showed the improvement achieved through the proposed hybrid approach. The work aims to provide the baselines needed to enable the metal Hybrid Additive Manufacturing of components with complex geometries where mandatory precision is required by integrating high accuracy machining operations as post-processing technique

Generation of two transgene-free human iPSC lines from CD133+ cord blood cells

We have generated two human induced pluripotent stem cell (iPSC) lines from CD133+ cells isolated from umbilical cord blood (CB) of a female child using non-integrative Sendai virus. Here we describe the complete characterization of these iPSC lines: PRYDi-CB5 and PRYDi-CB40