Structural optimization for dew-condensers using computational fluid dynamics

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Any: 2014, Tutor: Josep PerellóWater scarcity has been faced as one of the major threats to humankind this century. We here investigate a rather novel water collection device that wants to face this threat in an innovative form. We particularly find better geometries for the design of passive water collectors that take advantage of dew meteorological phenomena. We focus on the analysis of temperature distribution over a collection of dew-condenser surfaces by using Computational Fluid Dynamics. We detect key patterns for surface designs that maximize the cooling process by radiation while reducing heat transfer produced by convection. This is an especially innovative approach on air wells research field since the influence of geometries in the construction of condensers has had very little attention in the literature. The different geometries being tested allow us to clearly distinct between planar and funnel shapes in terms of efficiency. There are differences in temperature also between those geometries with folding on their faces and the ones without. Finally, we also evaluate the performance of the condensers in front of different wind directions. The findings from this highly multidisciplinary approach in collaboration with an architecture office will be useful for the construction of new dew-condensers in a near future

Contraction strategies of Tensor Networks for Quantum Circuit simulations

In the last years, the classical simulation of quantum systems is growing as a good approach to provide effcient approximations to quantum computers that are in the way of reaching quantum supremacy. An effcient way of performing simulations is through the use of tensor networks which can be described as a countable collection of tensors connected by contractions. The main advantage of this approach is that a quantum circuit can be easily mapped into a tensor network. This work studies the contraction of tensor networks that correspond to quantum circuits with different geometries and sizes. The method used to find the contraction path also affects the results, so the same circuits have been contracted for each path finding method. The information extracted is the size of the largest intermediate tensor in the contraction rather than computing the contraction itself. In the results it has been seen that the method used, the geometry and the size of a circuit have an impact on the size of the largest intermediate tensor of a contraction

The use of rapid prototyping techniques (RPT) to manufacture micro channels suitable for high operation pressures and uPIV

This paper aims to present a new methodology to manufacture micro-channels suitable for high operating pressures and micro particle image velocimetry (µPIV) measurements using a rapid-prototyping high-resolution 3D printer. This methodology can fabricate channels down to 250 µm and withstand pressures of up to 5 ± 0.2 MPa. The manufacturing times are much shorter than in soft lithography processes. The novel manufacturing method developed takes advantage of the recently improved resolution in 3D printers to manufacture an rapid prototyping technique part that contains the hose connections and a micro-channel useful for microfluidics. A method to assemble one wall of the micro-channel using UV curable glue with a glass slide is presented – an operation required to prepare the channel for µPIV measurements. Once built, the micro-channel has been evaluated when working under pressure and the grease flow behavior in it has been measured using µPIV. Furthermore, the minimum achievable channels have been defined using a confocal microscopy study. This technique is much faster than previous micro-manufacturing techniques where different steps were needed to obtain the micro-machined parts. However, due to current 3D printers ' resolutions (around 50 µm) and according to the experimental results, channels smaller than 250-µm2 cross-section should not be used to characterize fluid flow behaviors, as inaccuracies in the channel boundaries can deeply affect the fluid flow behavior. The present methodology is developed due to the need to validate micro-channels using µPIV to lubricate critical components (bearings and gears) in wind turbines. This novel micro-manufacturing technique overcomes current techniques, as it requires less manufacturing steps and therefore it is faster and with less associated costs to manufacture micro-channels down to 250-µm2 cross-section that can withstand pressures higher than 5 MPa that can be used to characterize microfluidic flow behavior using µPIV.Peer ReviewedPostprint (author's final draft

Microfluidics and MEMS technology for membranes

Postprint (published version

Performance Comparison of High Order Moments Blind Channel Identification

International audienc

Symposium review: Decomposing efficiency of milk production and maximizing profit

The dairy industry has focused on maximizing milk yield, as it is believed that this maximizes profit mainly through dilution of maintenance costs. Efficiency of milk production has received, until recently, considerably less attention. The most common method to determine biological efficiency of milk production is feed efficiency (FE), which is defined as the amount of milk produced relative to the amount of nutrients consumed. Economic efficiency is best measured as income over feed cost or gross margin obtained from feed investments. Feed efficiency is affected by a myriad of factors, but overall they could be clustered as follows: (1) physiological status of the cow (e.g., age, state of lactation, health, level of production, environmental conditions), (2) digestive function (e.g., feeding behavior, passage rate, rumen fermentation, rumen and hindgut microbiome), (3) metabolic partitioning (e.g., homeorhesis, insulin sensitivity, hormonal profile), (4) genetics (ultimately dictating the 2 previous aspects), and (5) nutrition (e.g., ration formulation, nutrient balance). Over the years, energy requirements for maintenance seem to have progressively increased, but efficiency of overall nutrient use for milk production has also increased due to dilution of nutrient requirements for maintenance. However, empirical evidence from the literature suggests that marginal increases in milk require progressively greater marginal increases in nutrient supply. Thus, the dilution of maintenance requirements associated with increases in production is partially overcome by a progressive diminishing marginal biological response to incremental energy and protein supplies. Because FE follows the law of diminishing returns, and because marginal feed costs increase progressively with milk production, profits associated with improving milk yield might, in some cases, be considerably lower than expected.info:eu-repo/semantics/publishedVersio

Los mensajes filatélicos contra la violencia hacia las mujeres

Objetivo: conocer la difusión mundial de sellos postales con mensajes contra la violencia hacia la mujer y describir sus elementos iconográficos. Material y método: consulta del catálogo Yvert et Tellier 2017 para la búsqueda de sellos sobre campañas contra la violencia hacia las mujeres. Análisis descriptivos de los sellos según la metodología de Panofsky. Se analizaron las imágenes en su contexto y se relacionaron con el momento y el motivo de la emisión del sello. Resultados: entre los años 1985 y 2017, se localizaron 126 sellos: 40 en Europa, 53 en América, 19 en África, 11 en Asia y 3 en Oceanía. La mayoría contiene leyendas con mensajes contra la violencia hacia la mujer. La simbología utilizada incluye: la paloma blanca (paz), el lazo violeta (denuncia contra la violencia), el lazo blanco (denuncia masculina contra la violencia), manos extendidas (alto a la violencia), flores blancas (inocencia o pureza), cadenas (esclavitud), llanto (sufrimiento), ojos tapados (privación de derechos), mariposa (libertad), la imagen de la diosa de la justicia y la relación entre símbolos masculinos y femeninos (igualdad). Asimismo, se localizaron sellos de mutilación genital, que aluden al tráfico de mujeres para la explotación sexual; en homenaje a personajes representativos de la lucha contra la violencia; y sellos que muestran recursos institucionales de soporte. Conclusiones: la representación de la violencia de género está presente en una gran cantidad de países, sobre todo de Europa y América. Los sellos pretenden concienciar a la sociedad sobre esta lacra social e insistir en la importancia de la educación para prevenir toda forma de violencia contra la mujer

Enabling novel Lab-on-chip applications through optimization of integrated micropillar pumps

Prediction and reduction of pressure drop and resistance flow in micropillar arrays is important for the design of microfluidic circuits used in different lab-on-a-chip and biomedical applications. In this work, a diamond microchannel integrated micropillar pump (dMIMP) with a resistance flow 35.5% lower than circular based micropillar pump (cMIMP) has been developed via the optimization of the fluid-dynamic behavior of different post shapes in a low aspect ratio (H/D ranged from 0.06 to 0.2) integrated pillar micro-channel. Flow through the fabricated samples has been numerically solved and experimentally measured, with an agreement higher than 90%. The analysis of the results indicates that although porosity can be a determinant parameter to predict the resistance flow of MIMP, other geometrical parameters like, side distance between posts or post shape, play a major role in this scenarioPeer Reviewe