On the relation between inward pointing velocity conditions

Inward pointing velocity conditions are important in the study of whether trajectories remain within sets (the so-called invariance or viability) and also to establish constraint qualifications (CQ) under which necessary conditions of optimality for control problem can be guaranteed to be nondegenerate NCO or normal. In our research on nondegenerate NCO we have studied different types of CQs in the form of inward pointing velocity (IPV) conditions, and, in particular, in which situation one type implies other type of IPV. Such findings are reported in the article.FCT Project PTDC/EEA -CRO/116014/2009 "Optimal Control in Constrained and Hybrid Nonlinear Systems

An integral-type constraint qualification for optimal control problems with state constraints

Relatório Técnico do Núcleo de Investigação Officina Mathematica.Standard necessary conditions of optimality (NCO) for constrained optimal control problems -- Maximum Principle type onditions -- may fail to provide useful information to select candidates to minimizers among the overall set of admissible solutions. This phenomenon is known as the degeneracy phenomenon and there has been continuing interest in the literature in proposing stronger forms of NCO that can be informative in such cases: the so-called nondegenerate NCO. The nondegenerate NCO proposed here are validunder a different set of hypothesis and under a constraint qualification of an integral-type that, in relation to some previous literature, can be verified for more problems.Fundação para a Ciência e a Tecnologia (FCT) Projecto FCT POSC/EEA-SRI/61831/200

Energy and thermal comfort management in a kindergarten school building in the South of Portugal in Winter conditions

In this work a numerical model, which simulates the buildings thermal response and evaluates the indoor environment comfort, in transient conditions, is used in the energy and thermal comfort management in a kindergarten school building in the South of Portugal in Winter conditions. After it's validation, this numerical model is applied in the evaluation of the building thermal behavior, using the indoor temperature field, and the occupants thermal comfort levels, using the PMV and PPD indexes. In the numerical model validation, experimental data and numerical values, for the indoor air temperature, are compared. In the experimental tests, for a typical Winter day, the outdoor and indoor environmental variables are measured. In the numerical simulation of the kindergarten school building, the 25 compartments, the 498 building main bodies and the 42 windows glasses, as well as all surrounding main buildings, are considered. The viability to build an indoor greenhouse, used to heat the cooled spaces, and the evolution of indoor thermal comfort level are analyzed

Extraction of Biocompatible Collagen From Blue Shark Skins Through the Conventional Extraction Process Intensification Using Natural Deep Eutectic Solvents

ERC-2016-CoG 725034The disposal of large amounts of skin waste resulting from the blue shark fishing industry presents several industrial and environmental waste management concerns. In addition, these marine subproducts are interesting sources of collagen, a fibrous protein that shows high social and economic interest in a broad range of biomedical, pharmaceutical, and cosmetic applications. However, blue shark wasted skins are a poorly explored matrix for this purpose, and conventional collagen recovery methodologies involve several pre-treatment steps, long extraction times and low temperatures. This work presents a new green and sustainable collagen extraction approach using a natural deep eutectic solvent composed of citric acid:xylitol:water at a 1:1:10 molar ratio, and the chemical characterization of the extracted collagen by discontinuous electrophoresis, thermogravimetric analysis, Fourier transformed infrared spectroscopy and circular dichroism. The extracted material was a pure type I collagen, and the novel approach presented an extraction yield 2.5 times higher than the conventional one, without pre-treatment of raw material and reducing the procedure time from 96 to 1 h. Furthermore, the in vitro cytotoxicity evaluation, performed with a mouse fibroblasts cell line, has proven the biocompatibility of the extracted material. Overall, the obtained results demonstrate a simple, quick, cheap and environmentally sustainable process to obtain marine collagen with promising properties for biomedical and cosmetic applications.publishersversionpublishe

Optimal control problems with nonregular mixed constraints

In this paper we derive necessary conditions for a simple class of mixedconstrained optimal control problems that do not satisfy known regularity conditionson the mixed constraints. Such problems are a particular class of nonregular problems.Notably the necessary conditions we derive are stated in terms of measures

Optimal control for an irrigation planning problem: characterisation of solution and validation of the numerical results

In a previous study, the authors developed the planning of the water used in the irrigation systems of a given farmland in order to ensure that the field cultivation is in a good state of preservation. This planning was modelled and tackled as an optimal control problem: minimize the water flow (control) so that the extent water amount in the soil (trajectory) fulfils the cultivation water requirements. In this paper, we characterize the solution of our problem guaranteeing the existence of the solution and applying the necessary and sufficient conditions of optimality. We validate the numerical results obtained previously, comparing the analytical and numerical solutions.PEst-OE/MAT/UI0013/2014 and PEST-C/FIS/UI607/2013, European Union FP7 (FP7-PEOPLE-2010-ITN, Grant Agreement no. 264735- SADCO), FCT projects PTDC/EEA-CRO/116014/2009 and PTDC/EEI-AUT/1450/201

Fractionated extraction of polyphenols from mate tea leaves using a combination of hydrophobic/ hydrophilic NADES

Publisher Copyright: © 2022 The AuthorsA new methodology for the selective extraction of antioxidants from mate tea leaves (and decaffeinated mate tea leaves), using different natural deep eutectic systems (NADES), is reported in this paper. A fractionated extraction was carried out and the optimization of the extraction conditions such as solid/liquid ratio, temperature, time, stirring and the use of ultrasound assisted extraction (UAE) technology was performed. The results demonstrate that a sequential extraction using, in a first step, an hydrophobic system Men:Lau (2:1) and, in a second step, an hydrophilic lactic acid-based NADES, leads to two distinct extracts: the first one rich in pigments and the second one rich in polyphenols. NADES systems were able to extract 30% more of the polyphenolic components of the mate tea leaves matrices, when compared with traditional solvents/techniques. Moreover, it has been shown that the incorporation of the extract in the NADES, compared to the same extract in aqueous medium was beneficial for the stabilization of the antioxidants. It maintains their functionality at least for three months, reaching 41% more versus the extracts obtained by traditional solvents/techniques. The absence of caffeine in the extracts did not shown to have any effects on the stability results.publishersversionpublishe

A special class of mixed constrained optimal control problems

The focus of this paper is on optimal control problems with mixed state and control inequality constraints. We identify a class of problems which can be associated with an auxiliary problem with both regular mixed constraints and pure state constraints. For that class of problems we derive a new set of necessary conditions of optimality. © 2007 EUCA