Nonlinear behavior of gelatin networks reveals a hierarchical structure

We investigate the strain hardening behavior of various gelatin networks-namely physical gelatin gel, chemically cross-linked gelatin gel, and a hybrid gel made of a combination of the former two-under large shear deformations using the pre-stress, strain ramp, and large amplitude oscillations shear protocols. Further, the internal structures of physical gelatin gels and chemically cross-linked gelatin gels were characterized by small angle neutron scattering (SANS) to enable their internal structures to be correlated with their nonlinear rheology. The Kratky plots of SANS data demonstrate the presence of small cross-linked aggregates within the chemically cross-linked network whereas, in the physical gelatin gels, a relatively homogeneous structure is observed. Through model fitting to the scattering data, we were able to obtain structural parameters, such as the correlation length (ξ), the cross-sectional polymer chain radius (Rc) and the fractal dimension (df) of the gel networks. The fractal dimension df obtained from the SANS data of the physical and chemically cross-linked gels is 1.31 and 1.53, respectively. These values are in excellent agreement with the ones obtained from a generalized nonlinear elastic theory that has been used to fit the stress-strain curves. The chemical cross-linking that generates coils and aggregates hinders the free stretching of the triple helix bundles in the physical gels.

Optimization of magnetoelectric composites based on electroactive polymers for energy harvesting and sensor application

Tese de Doutoramento em Engenharia de Materiais.

Materiais compósitos com incorporação de cânhamo industrial

Projeto de Investigação integrado de mestrado Internacional em Sustentabilidade do Ambiente Construído

Development of a model for occupational risk acceptance criteria definition in industrial settings

Doctoral Dissertation for PhD degree in Industrial and Systems Engineering

Flow updating: fault-tolerant aggregation for dynamic networks

Documento submetido para revisão pelos pares. A publicar em Journal of Parallel and Distributed Computing. ISSN 0743-7315

Upgrade of an industrial building: BIM model of the as-built situation and evaluation of modifications

Dissertação de mestrado integrado in Civil Engineering

A proteção cumulativa do design pelo Direito de Autor e pelo Direito da Propriedade Industrial: o caso especial do contrato de trabalho

Dissertação de mestrado em Direito dos Contratos e das Empresas

Feasibility of internally stiffened thin-walled beams for industrial applications

Several types of internally reinforced thin-walled beams are subjected to a feasibility evaluation of its mechanical behavior for industrial applications. The adapting of already existing efficient sandwich geometries to hollow-box beams of larger dimensions may reveal promising results. Novel types of sandwich beams under bending and torsion uncoupled loadings are studied in terms of stiffness behavior in static analysis. For the analysis of the solutions, the models are built using the Finite Element Method (FEM) software ANSYS Mechanical APDL. The feasibility of the novel beams was determined by the comparison of the stiffness behavior of the novel hollow-box beams with conventional hollow-box beams. An efficiency parameter was defined in order to determine the feasibility. It is found that the novel geometries represent an excellent improvement under bending loadings, better than under torsion loadings. Nevertheless, for bending and torsion combined loadings, if bending loads are predominant, the beams can still be interesting for some applications, in particular those with mobile parts.

A UML-based approach for modeling industrial control applications

The main purpose of the poster is to present how the Unified Modeling Language (UML) can be used for diagnosing and optimizing real industrial production systems. By using a car radios production line as a case study, the poster shows the modeling process that can be followed during the analysis phase of complex control applications. In order to guarantee the continuity mapping of the models, the authors propose some guidelines to transform the use cases diagrams into a single object diagram, which is the main diagram for the next phases of the development.

Valorization of agro-industrial wastes towards the production of rhamnolipids

In this work, oil mill wastewater (OMW), a residue generated during olive oil extraction, was evaluated as an inducer of rhamnolipid production. Using a medium containing as sole ingredients corn steep liquor (10%, v/v), sugarcane molasses (10%, w/v) and OMW (25%, v/v), Pseudomonas aeruginosa #112 produced 4.5 and 5.1 g of rhamnolipid per liter in flasks and reactor, respectively, with critical micelle concentrations as low as 13 mg/l. Furthermore, in the medium supplemented with OMW, a higher proportion of more hydrophobic rhamnolipid congeners was observed comparing with the same medium without OMW. OMW is a hazardous waste which disposal represents a serious environmental problem; therefore, its valorization as a substrate for the production of added-value compounds such as rhamnolipids is of great interest. This is the first report of rhamnolipid production using a mixture of these three agro-industrial by-products, which can be useful for the sustainable production of rhamnolipids.

Production of whey protein-based aggregates under ohmic heating

Formation of whey protein isolate protein aggregates under the influence of moderate electric fields upon ohmic heating (OH) has been monitored through evaluation of molecular protein unfolding, loss of its solubility, and aggregation. To shed more light on the microstructure of the protein aggregates produced by OH, samples were assayed by transmission electron microscopy (TEM). Results show that during early steps of an OH thermal treatment, aggregation of whey proteins can be reduced with a concomitant reduction of the heating chargeby reducing the come-up time (CUT) needed to reach a target temperatureand increase of the electric field applied (from 6 to 12 V cm1). Exposure of reactive free thiol groups involved in molecular unfolding of -lactoglobulin (-lg) can be reduced from 10 to 20 %, when a CUT of 10 s is combined with an electric field of 12 V cm1. Kinetic and multivariate analysis evidenced that the presence of an electric field during heating contributes to a change in the amplitude of aggregation, as well as in the shape of the produced aggregates. TEM discloses the appearance of small fibrillar aggregates upon the influence of OH, which have recognized potential in the functionalization of food protein networks. This study demonstrated that OH technology can be used to tailor denaturation and aggregation behavior of whey proteins due to the presence of a constant electric field together with the ability to provide a very fast heating, thus overcoming heat transfer limitations that naturally occur during conventional thermal treatments.

Hierarchical modelling of timber reference properties using probabilistic methods: Maximum Likelihood Method, Bayesian Methods and Probability Networks

In recent decades, an increased interest has been evidenced in the research on multi-scale hierarchical modelling in the field of mechanics, and also in the field of wood products and timber engineering. One of the main motivations for hierar-chical modelling is to understand how properties, composition and structure at lower scale levels may influence and be used to predict the material properties on a macroscopic and structural engineering scale. This chapter presents the applicability of statistic and probabilistic methods, such as the Maximum Likelihood method and Bayesian methods, in the representation of timber’s mechanical properties and its inference accounting to prior information obtained in different importance scales. These methods allow to analyse distinct timber’s reference properties, such as density, bending stiffness and strength, and hierarchically consider information obtained through different non, semi or destructive tests. The basis and fundaments of the methods are described and also recommendations and limitations are discussed. The methods may be used in several contexts, however require an expert’s knowledge to assess the correct statistic fitting and define the correlation arrangement between properties.

From perfect strangers to research partners: a study of relationships, resource sharing and perceived benefits within R&D cooperation networks

Doctoral thesis in Marketing and Strategy.

Optimização do processo de recolha de resíduos: desenvolvimento de ferramentas de investigação operacional para o problema de orientação de equipas com multi-restrições

Tese de Doutoramento em Engenharia Industrial e de Sistemas.

Horário por turnos : análise do seu efeito numa empresa do sector industrial

O presente estudo teve por objetivo analisar os possíveis efeitos do trabalho por turnos, incluindo o turno noturno, a nível da saúde, vida familiar e social, numa empresa do sector da indústria. Foi construído um questionário que abordava questões relativas aos dados sociodemográficos, organização temporal do trabalho, qualidade do sono, exigências da tarefa e envolvimento, saúde, vida familiar e social, e posteriormente foi aplicado a uma amostra de 24 trabalhadores com idades entre os 29 e os 52 anos (41,58±5,79 anos). Os resultados mostram uma tendência para doenças como a obesidade, colesterol elevado e manifestação de sintomas relacionados com problemas digestivos nos trabalhadores que trabalham por turnos à [sic] mais anos. Antes do primeiro turno noturno o tempo de sono é bastante reduzido e fica aquém do tempo que os trabalhadores sentem que necessitam dormir para se sentirem bem. O turno da tarde é o que permite os trabalhadores ficarem com um tempo de sono mais próximo desse “ideal”. Em relação à idade, todos os trabalhadores do grupo etário mais velho manifestam interrupções do sono diurno. Também se verifica um maior descontentamento destes trabalhadores com o tempo livre para realizar atividades que tragam bem-estar. Este estudo contribui para o conhecimento da realidade do trabalho por turnos na indústria e espera-se que desperte a procura de soluções que otimizem a vida destes trabalhadores.