Desempenho de modelos analíticos de previsão da contribuição de materiais compósitos no reforço ao corte de vigas de betão armado

Na presente comunicação são apresentados alguns modelos analíticos para previsão da contribuição de materiais compósitos no reforço ao corte de vigas de betão armado recentemente introduzidos nos códigos de dimensionamento, sendo o seu desempenho aferido por comparação entre os valores estimados pelas formulações analíticas com os registados numa base de dados contendo informação referente a mais de 200 programas experimentais.Os autores manifestam os seus agradecimentos ao apoio prestado pela Fundação para a Ciência e Tecnologia (FCT) no projecto POCI/ECM/59033/2004. O primeiro autor agradece a bolsa UMINHO/POCI-59033/BI/05 concedida ao abrigo deste projecto

Novas perspectivas para o desenvolvimento de modelos de dimensionamento ao corte de vigas de betão armado reforçadas com FRP colado externamente

Com o presente artigo pretende-se apresentar uma base de dados (BD) contendo os registos relativos a mais de 250 vigas reforçadas ao corte com materiais poliméricos reforçados com fibras (FRP) e ensaiadas em diversos programas experimentais conduzidos por diferentes autores. O desempenho dos modelos de dimensionamento propostos pelo fib, ACI, e pelas Norma Italiana CNR-DT200 e Norma Australiana CIDAR é aferido comparando o comportamento observado experimentalmente com as previsões obtidas por via analítica. Tendo por base os resultados registados na BD, foi efectuado um estudo paramétrico com o objectivo de avaliar a influência no desempenho dos modelos de dimensionamento de diversos factores não explicitamente considerados nas formulações analíticas que os suportam. Os resultados são analisados, interpretados e apontadas as limitações encontradas nos modelos de dimensionamento em estud

Reliability analysis of shear strengthening EBR FRP models

This work presents a statistically oriented study aiming to assess the reliability of some of the most well known design models available for the prediction of the contribution of fiber reinforced polymer (FRP) systems applied according to the externally bonded reinforcing (EBR) technique for the shear strengthening of reinforced concrete (RC) beams. Relevant data was collected from experimental programs carried out in recent years in the context of the shear strengthening with FRP, and an extended database was obtained. Using this data, the performance of fib, ACI, Italian and Australian design guidelines was appraised by means of comparing the contribution of the FRP shear systems predicted by the analytical formulations with those registered experimentally. In general, the obtained results were not very promising, since a large scatter of the design safety factor was observed and, for some cases, the contribution of the FRP systems predicted by the design models was highly unconservative, which may be a serious concern as these formulations may be currently being used in design practice.The study reported in this paper forms a part of the research programme Cutinemo, supported by FCT, PTDC/ECM/73099/2006

Design models for shear strengthening of reinforced concrete beams with externally bonded FRP composites : a statistical vs reliability approach

Fundação para a Ciência e a Tecnologia (FCT) - POCTI/ECM/59033/200

Adaptation and validation of Child Vulnerability Scale in Portuguese parents

info:eu-repo/semantics/publishedVersio

Adipokines and the Right Ventricle: The MESA-RV Study.

ObjectiveObesity is associated with changes in both right (RV) and left (LV) ventricular morphology, but the biological basis of this finding is not well established. We examined whether adipokine levels were associated with RV morphology and function in a population-based multiethnic sample free of clinical cardiovascular disease.MethodsWe examined relationships of leptin, resistin, TNF-α, and adiponectin with RV morphology and function (from cardiac MRI) in participants (n = 1,267) free of clinical cardiovascular disease from the Multi-Ethnic Study of Atherosclerosis (MESA)-RV study. Multivariable regressions (linear, quantile [25th and 75th] and generalized additive models [GAM]) were used to examine the independent association of each adipokine with RV mass, RV end-diastolic volume (RVEDV), RV end-systolic volume (RVESV), RV stroke volume (RVSV) and RV ejection fraction (RVEF).ResultsHigher leptin levels were associated with significantly lower levels of RV mass, RVEDV, RVESV and stroke volume, but not RVEF, after adjustment for age, gender, race, height and weight. These associations were somewhat attenuated but still significant after adjustment for traditional risk factors and covariates, and were completely attenuated when correcting for the respective LV measures. There were no significant interactions of age, gender, or race/ethnicity on the relationship between the four adipokines and RV structure or function.ConclusionsLeptin levels are associated with favorable RV morphology in a multi-ethnic population free of cardiovascular disease, however these associations may be explained by a yet to be understood bi-ventricular process as this association was no longer present after adjustment for LV values. These findings complement the associations previously shown between adipokines and LV structure and function in both healthy and diseased patients. The mechanisms linking adipokines to healthy cardiovascular function require further investigation

Casting the light of the theory of opposition onto Hohfeld's fundamental legal concepts

At the core of Hohfeld's contribution to legal theory is a conceptual framework for the analysis of the legal positions occupied by agents in intersubjective legal relations. Hohfeld presented a system of eight fundamental concepts relying on notions of opposition and correlation. Throughout the years, a number of authors have followed Hohfeld in applying the notion of opposition to analyze legal concepts. Many of these authors have accounted for Hohfeld's theory in direct analogy with the standard deontic hexagon. This paper reviews some of these accounts and extends them employing recent developments from opposition theory. In particular, we are able to extend application of opposition theory to an open conception of the law. We also account for the implications of abandoning the assumption of conflict-freedom and admitting seemingly conflicting legal positions. This enables a fuller analysis of Hohfeld's conceptual analytical framework. We also offer a novel analysis of Hohfeld's power positions.</p

Optimization of the thyristor valves design for TCR static VAR compensators

Describes a program developed to optimize the design of thyristor valves for Static VAR Compensators (SVC) of the Thysristor Controlled Reactors (TCR) type

New 3‐ethynylaryl coumarin‐based dyes for dssc applications: Synthesis, spectroscopic properties, and theoretical calculations

PTDC/QUI‐QOR/7450/2020 POCI‐01‐0145‐FEDER‐016387 UIDB/50006/2020 UIDP/50006/2020 RECI/BBB‐BQB/0230/2012 RECI/BBB‐BEP/0124/2012 2020.09047.BD PD/BD/135087/2017 PD/BD/145324/2019/ (G.M.) .A set of 3‐ethynylaryl coumarin dyes with mono, bithiophenes and the fused variant, thieno [3,2‐b] thiophene, as well as an alkylated benzotriazole unit were prepared and tested for dye‐sensitized solar cells (DSSCs). For comparison purposes, the variation of the substitution pattern at the coumarin unit was analyzed with the natural product 6,7‐dihydroxycoumarin (Esculetin) as well as 5,7‐dihydroxycomarin in the case of the bithiophene dye. Crucial steps for extension of the conjugated system involved Sonogashira reaction yielding highly fluorescent molecules. Spectroscopic characterization showed that the extension of conjugation via the alkynyl bridge resulted in a strong red‐shift of absorption and emission spectra (in solution) of approximately 73–79 nm and 52–89 nm, respectively, relative to 6,7‐dimethoxy‐4‐methylcoumarin (λabs = 341 nm and λem = 410 nm). Theoretical density functional theory (DFT) calculations show that the Lowest Unoccupied Molecular Orbital (LUMO) is mostly centered in the cyanoacrylic anchor unit, corroborating the high intramolecular charge transfer (ICT) character of the electronic transition. Photovoltaic performance evaluation reveals that the thieno [3,2‐b] thiophene unit present in dye 8 leads to the best sensitizer of the set, with a conversion efficiency (η = 2.00%), best VOC (367 mV) and second best Jsc (9.28 mA∙cm−2), surpassed only by dye 9b (Jsc = 10.19 mA∙cm−2). This high photocurrent value can be attributed to increased donor ability of the 5,7‐dimethoxy unit when compared to the 6,7 equivalent (9b).publishersversionpublishe