Thermodynamic Optimization of Tube-Fin Evaporators Operating under Frosting Conditions

In this study, the method of entropy generation minimization (i.e., design aimed at facilitating both heat, mass and fluid flows) is used to improve the evaporator geometry (aspect ratio and fin density) considering the irreversibilities produced by the heat and mass transfer, and viscous flow processes. A fully algebraic semi-empirical model was put forward to simulate the thermal-hydraulic behavior of tube-fin evaporator coils running under frosting conditions. The model predictions were validated against experimental data from Silva (2012), showing a good agreement between calculated and measured counterparts, with errors within a ±5% band for the cooling capacity and the air flow rate. The optimization exercise pointed out that high aspect ratio heat exchanger designs lead to minimum entropy generation in cases of fixed heat duty and air flow rate constrained by the characteristic curve of the fan

Flexible Transparency - a Study on Adaptive Thin Glass Façade Panels

Chemically strengthened thin glass (t < 2 mm) is a material that is stronger and due to its small thickness, more flexible than conventional window glass. As such, thin glass offers the possibility for lightweight and flexible glass façades that could change shape depending on external conditions.  This paper explores this concept and presents an MSc study on the use of this material in adaptive façade panels. The behavior of thin glass in this context depends on different factors. The glass thickness and strength define its bending limits, while the desired geometry and movement affect its overall stiffness and visual outcome. In order to integrate these factors, different configurations of panels were analyzed in numerical models. These analyses showed the importance of understanding the desired movement and geometry in order to correctly define the supports and degrees of freedom of the panel, avoiding stress concentration (particularly on the edges) and allowing for an unobstructed movement of the panel. The development of these analyses resulted in the conception of a design example of an adaptive façade panel, taking into consideration the design requirements developed in the research. Finally, as a proof of concept, a mock-up was built simulating the behavior of the design example developed in this research. Although there is still the need for research to be developed so that thin glass can become a building material, this research showed that this is possible and that interesting results, regarding visual effect, ventilation and dead load reduction (in larger scale, an environmental impact reduction is also possible) can be achieved.  Besides that, using thin glass in adaptive panels challenges the concept of glass as a static material, opening new possibilities for its use

Thermal-Hydraulic Optimization of Fan-Supplied Tube-Fin Evaporators for Frosting Conditions Aiming at Minimum Energy Consumption

This work is aimed at the optimal design (i.e. number of transversal and longitudinal tube rows, number of fins) of fan-supplied tube-fin evaporators for light commercial refrigeration applications operating under frosting conditions. Quasi-steady-state algebraic models were put forward for the refrigeration cycle and its components for computing not only the cooling capacity depletion due to the evaporator frosting over time, but also the changes experienced by the evaporating temperature and its effect on the compressor power. Transient, unsteady-state algebraic models were also advanced to account for the temperature and humidity variations inside the refrigerated compartment, and so the compressor runtime. The optimization exercise aiming at system-level energy consumption minimization revealed that, when the evaporator volume and width are held constrained, the lowest energy consumption was achieved for evaporators with evaporators with (3x6), (4x4) and (6x3) (transversal ´ longitudinal tubes), suggesting that the geometry is robust regarding the evaporator aspect ratio for fan-constrained conditions

Trial sequential analysis for assessing imprecision in GRADE evaluations – protocol for a methodological study

Abstract Background: Assessing statistical imprecision of summary estimates is an essential element in evaluating the strength of evidence. The GRADE framework recommends assessing imprecision by confidence intervals (CI) in relation to thresholds of interest and in selected cases to assess the relationship between the acquired information size and the calculated optimal information size (OIS). Trial sequential analysis (TSA) calculates multiplicity-adjusted confidence intervals and can be used to calculate a required information size. In a recent methodological study of 544 systematic reviews and meta-analysis reports of clinical trials with TSA, we gathered data regarding the methods used for grading imprecision, specifically regarding the impact of TSA (the METSA project). The questions regarding GRADE imprecision were initially superficially defined and were substantialized only during the project and in the preparations for this protocol. With this add-on study, we investigate the methods of grading imprecision in the GRADE framework by authors of systematic reviews and meta-analysis reports of clinical trials with TSA. Methods: The outlined methodological study will be pre-planned but designed with knowledge about existing but not yet reviewed data on the study questions. The METSA project was not initially designed for the questions raised in the current study protocol, which warrants a critical review of the collected data. We aim to improve precision and accuracy of the collected data regarding imprecision methodology by a redesign of selected data fields, adding new data fields to the data extraction form and a subsequent revision of the existing data extraction accordingly. For each individual study, we will extract or review data regarding the specified methodology including methods for calculating CI and OIS, and thresholds of interest (definitions of important benefit and/or harm). For each topic, we will assess completeness in transparency of described methods and protocolisation, including coherence with the protocol (if relevant). Results: We will report frequencies of observed methods, lack of transparency, and protocolisation. From data gathered in the METSA project, we will report the proportion of imprecision assessments that may have differed in their conclusions if the results of the TSA had been used. Informed by our findings, we will outline new suggestions on how to grade imprecision using TSA. Conclusion: This protocol outlines a methodological study of methods and reporting characteristics imprecision assessment within the GRADE framework in recent systematic reviews and meta-analysis reports of clinical trials utilising trial sequential analysis

Совершенствование конструкции подвижной рамы стартового устройства геохода

Рассмотрено новое решение подвижной рамы стартовой установки геохода. Спроектирован подвижный упор для элементов противовращения. Приведен результат прочностного расчета подвижного упора.A new solution of the mobile frame of the starting installation of the geodatabase is considered. A movable stop for anti-rotation elements has been designed. The result of the strength calculation of the movable stop is given

A narrativa urbana de Marcelo D’Salete, um intérprete do Brasil

Este artigo possuí como premissa desenvolver reflexão sociológica acerca da obra do quadrinista e ilustrador Marcelo D’Salete, artista que desenvolve uma obra das mais instigantes em relação ao processo de ser negro em um país como o Brasil, que nega a sua condição de sociedade racista ao mesmo tempo em que impede a sua população afrodescendente a sua condição cidadã e o pleno acesso direitos sociais. O que nos fez constituir esse estudo acerca dessa primeira fase de sua carreira, em que seus roteiros e narrativas gráficas já colocam em primeiro plano as vivências e experiências das populações afrodescendentes em suas relações - simbólicas ou concretas - de sociabilidades, partindo da sua própria conscientização racial e social em relação as condições de marginalização e racismo a que estas eram (são) submetidas ao longo de nossa história. Dando assim origem a um conjunto teórico basilar para se buscar entender o Brasil em todas as suas complexidades e contradições

A arte da desaparição como experimentação tateante de pensamento: contribuições à pesquisa educacional

This article aims to discuss the so-called essayistic form of thinking and its impact for the field of educational research. From the triangulation of forces between the thinking of Michel de Montaigne, Enrique Vila Matas and Gilles Deleuze-Felix Guattari, the study explores how, in the dawn of modern subjectivity, a certain art of portraiture produced from the essayistic form developed by Montaigne, produces a groping mode of thought experimentation whose horizon turns to a condition of disappearance. This work aims to study this distinctive portrait art dedicated to disappearance, focusing on its fabulous power, as well as explore its resonances in the ways we conceive the researcher's craft, especially in the educational field, as opposed to another portrait art called cartesian and developed by René Descartes. The discussion points out that the disappearance, by establishing another geography of thought, enables the educational researcher to mobilize other procedures in order to research the unthinkable.O artigo tem como objetivo discutir as implicações da forma ensaística de pensamento para o campo da pesquisa educacional. A partir da triangulação de forças entre o pensamento de Michel de Montaigne, Enrique Vila Matas e Gilles Deleuze-Félix Guattari, o estudo explora de que modo, na aurora da subjetividade moderna, certa arte do retrato, produzida a partir da forma ensaística desenvolvida por Montaigne, permitiu a emergência de um modo de experimentação tateante do pensamento, cujo horizonte se volta a uma condição de desaparição. O trabalho visa esmiuçar essa distinta arte do retrato dedicada à desaparição, focando-se em sua potência fabulatória, bem como explorar suas ressonâncias nos modos como concebemos o ofício do pesquisador, sobretudo no campo educacional, em contraposição a outra arte de retrato denominada cartesiana. Por fim, a discussão aponta que a desaparição, ao instaurar outra geografia de pensamento, possibilita ao pesquisador educacional mobilizar procedimentos outros tendo em vista ensaiar o impensável