Experimental assessment of mixing layer scaling laws in Rayleigh-Taylor instability

We assess experimentally the scaling laws that characterize the mixing region produced by the Rayleigh-Taylor instability in a confined porous medium. In particular, we wish to assess experimentally the existence of a superlinear scaling for the growth of the mixing region, which was observed in recent two-dimensional simulations. To this purpose, we use a Hele-Shaw cell. The flow configuration consists of a heavy fluid layer overlying a lighter fluid layer, initially separated by a horizontal, flat interface. When small perturbations of concentration and velocity fields occur at the interface, convective mixing is eventually produced: Perturbations grow and evolve into large finger-like convective structures that control the transition from the initial diffusion-dominated phase of the flow to the subsequent convection-dominated phase. As the flow evolves, diffusion acts to reduce local concentration gradients across the interface of the fingers. When the gradients become sufficiently small, the system attains a stably-stratified state and diffusion is again the dominant mixing mechanisms. We employ an optical method to obtain high-resolution measurements of the density fields and we perform experiments for values of the Rayleigh-Darcy number (i.e., the ratio between convection and diffusion) sufficiently large to exhibit all the flow phases just described, which we characterize via the mixing length, a measure of the extension of the mixing region. We are able to confirm that the growth of the mixing length during the convection-dominated phase follows the superlinear scaling predicted by previous simulations

Effect of dietary essential oils supplementation on growth performance, protein digestibility and digestive enzymes in juvenile gilthead seabream fed a low fishmeal diet

Dissertação de mestrado, Aquacultura e Pescas (Aquacultura), Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2013A study was undertaken to evaluate the efficacy of supplemental essential oils on the growth performance, protein digestibility and digestive enzyme activities in juvenile gilthead seabream fed a plant protein-rich diet. Four practical diets were formulated to be isonitrogenous (crude protein, 45.4% DM), isolipidic (18.5% DM) and isoenergetic (gross energy 21.4 kJ/g DM). The control diet (CTRL) was formulated with low levels of marine-derived proteins (19%). The same basal formulation was supplemented with a commercial blend of anis, citrus and oregano essential oils at 1.2 g/kg (diet Phyto C), a similar blend but available in an encapsulated form at 0.2 g/kg (diet Phyto E) and this same encapsulated product (0.2 g/kg) together with an autolysed yeast (1 g/kg) made up the third test diet (diet Phyto E+AY). Triplicate groups of 20 gilthead seabream, with a mean initial weight of 27.9 2.1 g were fed one of the four experimental diets during 63 days. At the end of the trial, the specific growth rate of seabream was not significantly affected (P>0.05) by the dietary supplements. Moreover, dietary supplementation had no effect (P>0.05) on the apparent digestibility of protein. However, fish fed the various supplemented feeds showed significantly lower (P0.05) by the dietary treatments, but fish fed diets supplemented with the essential oils showed a significant reduction (P0.05) pela suplementação alimentar. Por outro lado, a suplementação da dieta não teve efeito (P>0.05) sobre a digestibilidade aparente da proteína. No entanto, os peixes alimentados com as diferentes rações suplementadas, apresentaram uma redução significativa (P 0,05) pelos tratamentos alimentares, mas os peixes alimentados com dietas suplementadas com os óleos essenciais mostraram uma redução significativa (P <0,05) das perdas metabólicas de azoto. Os peixes alimentados com dieta Phyto E + AY mostraram um aumento da actividade (P <0,05) da fosfatase alcalina e leucina alanina peptidase. Todos os suplementos fitogênicos reforçaram (P <0,05) a atividade da pepsina digestiva, enquanto a atividade da lipase foi pouco afetada pelos tratamentos alimentares. Em termos gerais, a suplementação dos alimentos com óleos essenciais contribuiu para uma redução do FCR e uma melhoria da retenção de proteínas e de gordura em juvenis de dourada alimentados com uma dieta baixa em farinha de peixe

Astringency removal of 'Giombo' persimmon with ethanol sub-doses

O objetivo do trabalho foi avaliar a eficácia da aplicação de subdosagens de etanol na remoção da adstringência de caqui 'Giombo'. Além disso, foi avaliada a influência da temperatura e do tempo de exposição ao etanol no processo de destanização dos frutos. Assim, foram testadas diferentes doses de etanol (1,75; 3,5 e 7mL kg-1 ou 0,3 e 0,6mL L-1 de câmara-1), tempos de exposição (6, 12, 24 e 36h) e temperaturas de aplicação dos tratamentos e de armazenamento após a aplicação (5, 20 e 24&deg;C). A exposição dos frutos à concentração de 1,75mL de etanol, durante 12 horas, foi suficiente para destanizar completamente os frutos. Após a aplicação dos tratamentos, os frutos levaram quatro dias para estarem aptos ao consumo. A refrigeração de caquis 'Giombo', após o tratamento com etanol, não influenciou o posterior processo de polimerização dos taninos solúveis.The objective of this research was to evaluate ethanol sub-doses efficacy on the astringency removal of 'Giombo'. Additionally, it was evaluated the influence of temperature and ethanol exposure time on fruit deastringency. Thus, experiments were carried out with different exposition times (6, 12, 24 and 36h) and ethyl alcohol concentrations (1.75; 3.5 e 7mL kg-1 or 0.3 and 0.6mL L-1 of chamber). Fruit exposition to ethanol concentration of 1.75mL during 12 h was sufficient to remove completely the persimmon fruit astringency. After the treatment application, the fruits needed 4 days to become suitable to consumption. The process of tannin polymerization is not influenced by cold storage

Use Performance and Management of Biodegradable Fluids as Transformer Insulation

In recent years, the use of biodegradable fluids as liquid insulation for distribution and power transformers is spreading. The main biodegradable fluids used are natural and synthetic esters, although biodegradable hydrocarbons have been recently proposed. Biodegradable fluids have a much lower environmental impact than mineral oil, limiting the risk of soil contamination in leaks, which makes them a suitable solution for applications such as offshore transformers or railway transformers. Additionally, these fluids have a higher flash point than conventional mineral oils, which dramatically reduces the risk of fire and collateral damage derived from explosion and fire. Despite these advantageous factors, there are still some aspects that hinder the broadening of their use, such as the difference in thermal properties or the lack of accepted maintenance procedures for transformers that use them as liquid insulation. This paper presents the current status of biodegradable insulating fluids, analyzing some of their properties and discussing the aspects that are still to be investigated in order to make them a real alternative to petroleum-based fluids.Part of the work was performed during secondments and short visits between University of Valle, University Carlos III of Madrid and University of Cantabria executed in the framework of the BIOTRAFO project “Raising knowledge and developing technology for the design and deployment of high-performance power transformers immersed in biodegradable fluids”, H2020-MSCA-RISE-2018- 823969, 2019-21. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 823969. Also, we acknowledge the support of the Spanish Ministry of Science and Innovation by means of the National Research Project Asset management of biodegradable-fluid-based transformers (PID2019-107126RB-C21/AEI/10.13039/501100011033 and PID2019-107126RB-C22/AEI/ 10.13039/501100011033)

Effect of cast rectifiers on the marginal fit of UCLA abutments

OBJECTIVES: This study assessed the effect of cast rectifiers on the marginal misfit of cast UCLA abutments compared to premachined UCLA abutments. The influence of casting and porcelain baking on the marginal misfit of these components was also investigated. METHODS: Two groups were analyzed: test group - 10 cast UCLA abutments, finished with cast rectifier and submitted to ceramic application; control group - 10 premachined UCLA abutments, cast with noble metal alloy and submitted to ceramic application. Vertical misfit measurements were performed under light microscopy. In the test group, measurements were performed before and after the use of cast rectifiers, and after ceramic application. In the control group, measurements were performed before and after casting, and after ceramic application. Data were submitted to statistical analysis by ANOVA and Tukey's test (a= 5%). RESULTS: The use of cast rectifiers significantly reduced the marginal misfit of cast UCLA abutments (from 25.68mm to 14.83mm;

Design Of the Approximation Function of a Pedometer based on Artificial Neural Network for the Healthy Life Style Promotion in Diabetic Patients

The present study describes the design of an Artificial Neural Network to synthesize the Approximation Function of a Pedometer for the Healthy Life Style Promotion. Experimentally, the approximation function is synthesized using three basic digital pedometers of low cost, these pedometers were calibrated with an advanced pedometer that calculates calories consumed and computes distance travelled with personal stride input. The synthesized approximation function by means of the designed neural network will allow to reply the calibration experiment for multiple patients with Diabetes Mellitus in Healthy Life Style promotion programs. Artificial Neural Networks have been developed for a wide variety of computational problems in cognition, pattern recognition, and decision making. The Healthy Life Style refer to adequate nutrient ingest, physical activity, time to rest, stress control, and a high self-esteem. The pedometer is a technological device that helps to control the physical activity in the diabetic patient. A brief description of the Artificial Neural Network designed to synthesize the Approximation Function, the obtained Artificial Neural Network structure and results in the Approximation Function synthesis for three patients are presented. The advantages and disadvantages of the method are discussed and our conclusions are presented

Use performance and management of biodegradable fluids as transformer insulation

In recent years, the use of biodegradable fluids as liquid insulation for distribution and power transformers is spreading. The main biodegradable fluids used are natural and synthetic esters, although biodegradable hydrocarbons have been recently proposed. Biodegradable fluids have a much lower environmental impact than mineral oil, limiting the risk of soil contamination in leaks, which makes them a suitable solution for applications such as offshore transformers or railway transformers. Additionally, these fluids have a higher flash point than conventional mineral oils, which dramatically reduces the risk of fire and collateral damage derived from explosion and fire. Despite these advantageous factors, there are still some aspects that hinder the broadening of their use, such as the difference in thermal properties or the lack of accepted maintenance procedures for transformers that use them as liquid insulation. This paper presents the current status of biodegrad able insulating fluids, analyzing some of their properties and discussing the aspects that are still to be investigated in order to make them a real alternative to petroleum-based fluids.Part of the work was performed during secondments and short visits between University of Valle, University Carlos III of Madrid and University of Cantabria executed in the framework of the BIOTRAFO project “Raising knowledge and developing technology for the design and deployment of high-performance power transformers immersed in biodegradable fluids”, H2020-MSCA-RISE-2018- 823969, 2019-21. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 823969. Also, we acknowledge the support of the Spanish Ministry of Science and Innovation by means of the National Research Project Asset management of biodegradable-fluid-based transformers (PID2019-107126RB C21/AEI/10.13039/501100011033 and PID2019-107126RB-C22/AEI/ 10.13039/501100011033)

Algoritmos paralelos sobre arquitecturas multicluster y GRID

Esta línea de I/D se enfoca en la especificación, desarrollo y evaluación de algoritmos paralelos sobre arquitecturas multicluster y su evolución a GRID.\nLos temas fundamentales se relacionan con la implementación de algoritmos paralelos sobre arquitecturas distribuidas débilmente acopladas, la utilización de middleware de grid como soporte para el uso de esquemas multicluster y el desarrollo de modelos de predicción de performance para estas arquitecturas.\nEn este proyecto cooperan otras 3 Universidades Nacionales de Argentina (UN Comahue, UN Sur, UN San Luis) y se está trabajando con la red de Universidades iberoamericanas del proyecto CyTED “Tecnología GRID como motor de desarrollo regional”.Eje: Procesamiento Concurrente, Paralelo y Distribuid

Application of biodegradable fluids as liquid insulation for distribution and power transformers

In the last years the use of biodegradable fluids as liquid insulation for distribution and power transformers is becoming more common. The main biodegradable fluids are the natural and synthetic esters, although biodegradable hydrocarbons have been recently proposed as well. Biodegradable fluids have a much lower environmental impact than mineral oil, limiting the risk of soil contamination in case of leaks what makes them a suitable solution for some applications, as off-shore transformers or railway transformers. Additionally, these fluids have higher flash point than conventional mineral oils what reduces dramatically the risk of fire and collateral damage derived from explosion and fire. Despite of these advantageous factors, there are still some aspects that hinders the spread of their use, such as the difference on thermal properties, the lack of accepted maintenance procedures and the price. This paper presents the current situation of biodegradable insulating fluids, analyzing some of their properties and discussing the aspects that are still to be investigated to make them a real alternative to petroleum-based fluids.This work was supported in part by the European Union's Horizon 2020 Research and Innovation Programme through the Marie Sklodowska-Curie under Grant 823969, in part by the Ministry of Universities and Innovation Economy through Grants DPI2015-71219-C2 and PID2019-107126RB-C21

Application of biodegradable fluids as liquid insulation for distribution and power transformers

In the last years the use of biodegradable fluids as liquid insulation for distribution and power transformers is becoming more common. The main biodegradable fluids are the natural and synthetic esters, although biodegradable hydrocarbons have been recently proposed as well. Biodegradable fluids have a much lower environmental impact than mineral oil, limiting the risk of soil contamination in case of leaks what makes them a suitable solution for some applications, as off-shore transformers or railway transformers. Additionally, these fluids have higher flash point than conventional mineral oils what reduces dramatically the risk of fire and collateral damage derived from explosion and fire. Despite of these advantageous factors, there are still some aspects that hinders the spread of their use, such as the difference on thermal properties, the lack of accepted maintenance procedures and the price. This paper presents the current situation of biodegradable insulating fluids, analyzing some of their properties and discussing the aspects that are still to be investigated to make them a real alternative to petroleum-based fluidsThis work was supported in part by the European Union’s Horizon 2020 Research and Innovation Programme through the Marie Sklodowska-Curie under Grant 823969, in part by the Ministry of Universities and Innovation Economy through Grants DPI2015-71219-C2 and PID2019-107126RB-C21