A Piezoelectric Device for Measurement and Power Harvesting Applications

Com o apoio RAADRI.With the fast growth of wireless communications between nodes/sensor units, devices installed in remote places require power energy supply solutions to assure their functionally and data communication capabilities. For these applications energy harvesting takes place as a good solution, to increase the availability of energy, in opposition to the conventional systems of energy supply. Regenerative energy sources like thermoelectric, magnetic, piezoelectric, and/or renewable sources such as photovoltaic, wind, among others, allowed the development of different powering solutions for sensor units. The purpose of this work is to characterize a piezoelectric device to measure and capture mechanical vibrations from equipments, structures and piping vibrations, as well as from other sources. The study is carried out taking into account the power supply capabilities of piezoelectric devices as a function of the amplitude and frequency of the vibration stimulus, as well as, the electrical characteristics of the load circuit

levels in human milk

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Ferramenta de modelação desenvolvida em ambiente web para apoio à gestão de albufeiras

A utilização das tecnologias de informação e comunicação no caso específico da gestão de recursos hídricos, em que a incerteza associada aos processos hidrológicos determina um grau de dificuldade acrescido, revela-se essencial. Desta forma, o desenvolvimento de ferramentas que permitam a consulta de dados de redes de monitorização hidrológica, de previsões meteorológicas e de resultados de simulação em ambientes de múltiplas plataformas, fixas ou móveis, é uma das tarefas fundamentais para a incorporação das tecnologias de informação nos processos correntes de gestão de recursos hídricos. No presente trabalho apresenta-se uma ferramenta, desenvolvida para ambiente web, que permite consultar informação e operar modelos hidráulicos de simulação de barragens e respetivas albufeiras. A interface é adaptável a cada caso de estudo e poderá ser desenvolvida com diferentes tipos de software de modelação hidrológica e hidrodinâmica, considerando as necessidades estabelecidas pelo conjunto dos seus utilizadores. A partir da interface é possível estabelecer as condições de fronteira definidas para cada modelo, aplicar o modelo e visualizar os resultados de simulações dinâmicas. A aplicabilidade da ferramenta desenvolvida é demonstrada em exemplos de implementação em diversas albufeiras situadas no rio Guadiana (Empreendimento de Fins Múltiplos de Alqueva, Portugal

Balanço de nutrientes no braço sul do estuário do rio Mondego

Na sequência de estudos realizados no domínio da análise de vulnerabilidade da costa litoral portuguesa, entendeu-se pertinente desenvolver um programa de investigação sobre o braço sul do estuário do rio Mondego visando, fundamentalmente, os seguintes aspectos: caracterização das marés, caudais fluviais e descargas de fontes poluidoras; modelação hidrodinâmica do sistema; avaliação do balanço anual de nutrientes; análise da vulnerabilidade deste sistema à eutrofização. Neste trabalho procedeu-se à modelação do sistema utilizando um modelo de qualidade unidimensional (DUFLOW) e os dados existentes. A não adopção, nesta fase, dum modelo multidimensional deve-se não só à não simultaneidade das medições dos parâmetros nos vários pontos de amostragem, mas, sobretudo, ao objectivo do presente trabalho: estimar o balanço de nutrientes neste sistema estuarino

Mobility of contaminants in relation to dredging operations in a mesotidal estuary (Tagus Estuary, Portugal)

During the construction of a New Bridge over the Tagus estuary 2.5 million tons of sediments were dredged, part of this quantity being contaminated material. The extension and intensity of the water turbidity associated with dredging operating varied with the tidal conditions but the resuspended material collected near the bucket dredger did not present a concentration increment in metals and PCB, when compared to the estuarine suspended sediments. The calculated distribution coefficients suggest that some contaminants in solids near the dredger were not in equilibrium with the water. A 24-hour laboratory experiment demonstrated the complexity and quickness of anoxic sediments oxidation. In such a short period of time metals in the solids change their fractionation. A second laboratory simulation showed that mussels accumulate metals and PCB congeners when placed in turbid aerated water

Ethics issues experienced in HBM within Portuguese health surveillance and research projects

Background: In keeping with the fundamental practice of transparency in the discussion and resolution of ethics conflicts raised by research, a summary of ethics issues raised during Portuguese biomonitoring in health surveillance and research is presented and, where applicable, their resolution is described. Methods: Projects underway aim to promote the surveillance of public health related to the presence of solid waste incinerators or to study associations between human exposure to environmental factors and adverse health effects. The methodological approach involves biomonitoring of heavy metals, dioxins and/or other persistent organic pollutants in tissues including blood, human milk and both scalp and pubic hair in groups such as the general population, children, pregnant women or women attempting pregnancy. As such, the projects entail the recruitment of individuals representing different demographic and health conditions, the collection of body tissues and personal data, and the processing of the data and results. Results: The issue of autonomy is raised during the recruitment of participants and during the collection of samples and data. This right is protected by the requirement for prior written, informed consent from the participant or, in the case of children, from their guardian. Recruitment has been successful, among eligible participants, in spite of incentives rarely being offered. The exception has been in obtaining guardians' consent for children's participation, particularly for blood sampling. In an attempt to mitigate the harm-benefit ratio, current research efforts include alternative less invasive biomarkers. Surveys are currently being conducted under contract as independent biomonitoring actions and as such, must be explicitly disclosed as a potential conflict of interests. Communication of results to participants is in general only practised when a health issue is present and corrective action possible. Concerning human milk a careful approach is taken, considering breast-feeding's proven benefits. Conclusion: No national legislation currently accounts for the surveillance component of biomonitoring as distinct from research. Ethics issues arising within the domain of research are resolved according to available regulations. For issues encountered during surveillance, the same principles are used as guidance, completed by the authors' best judgement and relevant ethics committees' findings.Fundação para a Ciência e a Tecnologia with participation by FEDER, under POCI2010; ref. POCI/ SAU-ESP/58298/2004 (VAEDA) and POCI/SAU-ESP/62115/2004 (FEXHEBIO

Design of kinematic connectors for microstructured materials produced by additive manufacturing

The main characteristic of materials with a functional gradient is the progressive composition or the structure variation across its geometry. This results in the properties variation in one or more specific directions, according to the functional application requirements. Cellular structure flexibility in tailoring properties is employed frequently to design functionally-graded materials. Topology optimisation methods are powerful tools to functionally graded materials design with cellular structure geometry, although continuity between adjacent unit-cells in gradient directions remains a restriction. It is mandatory to attain a manufacturable part to guarantee the connectedness between adjoining microstructures, namely by ensuring that the solid regions on the microstructure’s borders i.e., kinematic connectors) match the neighboring cells that share the same boundary. This study assesses the kinematic connectors generated by imposing local density restrictions in the initial design domain (i.e., nucleation) between topologically optimised representative unit-cells. Several kinematic connector examples are presented for two representatives unit-cells topology optimised for maximum bulk and shear moduli with different volume fractions restrictions and graduated Young’s modulus. Experimental mechanical tests (compression) were performed, and comparison studies were carried out between experimental and numerical Young’s modulus. The results for the single maximum bulk for the mean values for experimental compressive Young’s modulus (Ex¯) with 60%Vf show a deviation of 9.15%. The single maximum shear for the experimental compressive Young’s modulus mean values (Ex¯) with 60%Vf, exhibit a deviation of 11.73%. For graded structures, the experimental mean values of compressive Young’s moduli (Ex¯), compared with predicted total Young’s moduli (ESe), show a deviation of 6.96 for the bulk graded structure. The main results show that the single type representative unit-cell experimental Young’s modulus with higher volume fraction presents a minor deviation compared with homogenized data. Both (i.e., bulk and shear moduli) graded microstructures show continuity between adjacent cells. The proposed method proved to be suitable for generating kinematic connections for the design of shear and bulk graduated microstructured materials.This research was funded by the Portuguese Science Funding Foundation FCT—Fundação para a Ciência e a Tecnologia (Grant No. SFRH/BD/130908/2017); PAMI—Portuguese Additive Manufacturing Initiative (Project nº22158—SAICT—AAC—01/SAICT/2016), CDRSP (UIDB/04044/2020), (UIDP/04044/2020); Add.Additive—add additive manufacturing to Portuguese industry (POCI-01- 0247-FEDER-024533)

Estratégias de saúde pública relativas à exposição a dioxinas : programas de vigilância epidemiológica ambiental : um exemplo de aplicação

A quantificação da exposição humana a dioxinas torna imprescindível o recurso à monitorização destes compostos no organismo humano, quando o objectivo é relacionar exposição e efeitos adversos na saúde dos indivíduos, e, por maioria de razão, quando os efeitos visados são os precoces, antes do aparecimento dos sinais clínicos. O leite materno é uma das matrizes humanas mais convenientes para a biomonitorização de dioxinas, na medida em que, embora referente a um único segmento demográfico em condições fisiológicas específicas e a um período muito reduzido na vida média dum indivíduo, permite obter informação sobre a exposição a estes compostos, quer especificamente para um importante sector da população, quer mesmo para a população geral, relativamente à qual é de extrema utilidade como indicador de exposição a este tipo de compostos, em programas de vigilância para avaliação de tendências geográficas e/ou temporais. Mas a sua maior vantagem é ainda a de poder fornecer informação sobre os níveis de dioxinas nas mulheres durante a gravidez e amamentação e, consequentemente, sobre a exposição pré-natal, dada a capacidade que as dioxinas têm de atravessar a barreira placentária e atingir o feto, e sobre a exposição pós-natal, uma vez que ocorre a transferência destes químicos, das mães aos filhos, através da amamentação, e que o leite pode constituir, para os lactentes, o único alimento, num período que não sendo muito longo na vida média de cada indivíduo, pode ser relevante em termos da exposição a estes compostos. Numa perspectiva de Saúde Pública, seria portanto desejável que qualquer estratégia relativa à exposição humana a dioxinas, desenvolvida com vista a melhorar a base de avaliação do risco para a saúde das crianças, ou para definir e adoptar medidas cientificamente fundamentadas de controlo e redução das fontes e minimização da exposição ambiental, passasse pela biomonitorização daqueles compostos no leite materno. No presente trabalho, revêem-se vantagens, desvantagens e condições da utilização do leite materno para quantificar a exposição, sobretudo perinatal, a dioxinas e descrevem-se exemplos de aplicação em curso, no âmbito de Programas de Vigilância Epidemiológica Ambiental relativos a unidades de incineração de resíduos sólidos, a operar na Área Metropolitana de Lisboa (Norte) e na Região Autónoma da Madeira

Co2 efflux, co2 concentration and photosynthetic refixation in stems of Eucalyptus globulus (Labill.)

Research PaperIn spite of the importance of respiration in forest carbon budgets, the mechanisms by which physiological factors control stem respiration are unclear. An experiment was set up in a Eucalyptus globulus plantation in central Portugal with monoculture stands of 5-year-old and 10-year-old trees. CO2 efflux from stems under shaded and unshaded conditions, as well as the concentration of CO2 dissolved in sap [CO2 *], stem temperature, and sap flow were measured with the objective of improving our understanding of the factors controlling CO2 release from stems of E. globulus. CO2 efflux was consistently higher in 5-year-old, compared with 10-year-old, stems, averaging 3.4 versus 1.3 mmol m22 s21, respectively. Temperature and [CO2 *] both had important, and similar, influences on the rate of CO2 efflux from the stems, but neither explained the difference in the magnitude of CO2 efflux between trees of different age and size. No relationship was found between efflux and sap flow, and efflux was independent of tree volume, suggesting the presence of substantial barriers to the diffusion of CO2 from the xylem to the atmosphere in this species. The rate of corticular photosynthesis was the same in trees of both ages and only reduced CO2 efflux by 7%, probably due to the low irradiance at the stem surface below the canopy. The younger trees were growing at a much faster rate than the older trees. The difference between CO2 efflux from the younger and older stems appears to have resulted from a difference in growth respiration rather than a difference in the rate of diffusion of xylemtransported CO