8,594 research outputs found

    Análise da Estrutura de um Edifício em Betão Armado Usando um Método dos Elementos Finitos

    Get PDF
    Pretende-se, utilizando o Modelo da Elasticidade Linear em freeFEM++, determinar os esforços e deslocamentos de um edifício alto submetido apenas à acção do peso próprio da estrutura e, efectuar estudos comparativos dos resultados obtidos com o SAP2000. O trabalho inicia-se com a introdução da teoria da elasticidade linear, onde são feitas as deduções das Equações de Compatibilidade, Equilíbrio e as Leis Constitutivas, de modo a resolver numericamente o problema de Elasticidade Linear mencionado. O método de elementos finitos será implementado em freeFEM++ com auxílio do GMSH que é uma poderosa ferramenta com capacidade de gerar automaticamente malhas tridimensionais de elementos finitos e com relativa facilidade de pré e pós-processamento.INSTITUTO SUPERIOR DE ENGENHARIA DE LISBOA: Departamento de Engenharia Civi

    AuditorĂ­a ambiental: nuevos caminos en el control externo.

    Get PDF
    El Estado, así como la sociedad, viene sufriendo diversas alteraciones. Consciente de estos cambios la auditoria gubernamental también pasa por un proceso de transformación. Entre las innumerables áreas a controlar, surge un nuevo campo que la auditoria gubernamental debe explotar: el Medio Ambiente. Lejos de la pretensión de agotar el asunto, el presente estudio trata de demostrar la aplicabilidad de una auditoria ambiental en el ámbito de una Entidad de Fiscalización Superior (EFS). Para ello, se presenta un caso práctico aplicado a las áreas protegidas de diez Parques Naturales, examinados por completo.Auditoría ambiental, Entidad de Fiscalización Superior (EFS).

    Heterotrophy as a tool to overcome the long and costly autotrophic scale-up process for large scale production of microalgae

    Get PDF
    Industrial scale-up of microalgal cultures is often a protracted step prone to culture collapse and the occurrence of unwanted contaminants. To solve this problem, a two-stage scale-up process was developed - heterotrophically Chlorella vulgaris cells grown in fermenters (1st stage) were used to directly inoculate an outdoor industrial autotrophic microalgal production unit (2nd stage). A preliminary pilot-scale trial revealed that C. vulgaris cells grown heterotrophically adapted readily to outdoor autotrophic growth conditions (1-m3 photobioreactors) without any measurable difference as compared to conventional autotrophic inocula. Biomass concentration of 174.5 g L-1, the highest value ever reported for this microalga, was achieved in a 5-L fermenter during scale-up using the heterotrophic route. Inocula grown in 0.2- and 5-m3 industrial fermenters with mean productivity of 27.54 ± 5.07 and 31.86 ± 2.87 g L-1 d-1, respectively, were later used to seed several outdoor 100-m3 tubular photobioreactors. Overall, all photobioreactor cultures seeded from the heterotrophic route reached standard protein and chlorophyll contents of 52.18 ± 1.30% of DW and 23.98 ± 1.57 mg g-1 DW, respectively. In addition to providing reproducible, high-quality inocula, this two-stage approach led to a 5-fold and 12-fold decrease in scale-up time and occupancy area used for industrial scale-up, respectively.Agência financiadora project FERMALG 017608 Fundacao para a Ciencia e a Tecnologia (FCT) UID/Multi/04326/2019 project FERMALG (AVISO) 32/SI/2015info:eu-repo/semantics/publishedVersio

    Maternal short stature does not predict their children's fatness indicators in a nutritional dual-burden sample of urban Mexican Maya.

    Get PDF
    The co-existence of very short stature due to poor chronic environment in early life and obesity is becoming a public health concern in rapidly transitioning populations with high levels of poverty. Individuals who have very short stature seem to be at an increased risk of obesity in times of relative caloric abundance. Increasing evidence shows that an individual is influenced by exposures in previous generations. This study assesses whether maternal poor early life environment predicts her child's adiposity using cross sectional design on Maya schoolchildren aged 7-9 and their mothers (n = 57 pairs). We compared maternal chronic early life environment (stature) with her child's adiposity (body mass index [BMI] z-score, waist circumference z-score, and percentage body fat) using multiple linear regression, controlling for the child's own environmental exposures (household sanitation and maternal parity). The research was performed in the south of Merida, Yucatan, Mexico, a low socioeconomic urban area in an upper middle income country. The Maya mothers were very short, with a mean stature of 147 cm. The children had fairly high adiposity levels, with BMI and waist circumference z-scores above the reference median. Maternal stature did not significantly predict any child adiposity indicator. There does not appear to be an intergenerational component of maternal early life chronic under-nutrition on her child's obesity risk within this free living population living in poverty. These results suggest that the co-existence of very short stature and obesity appears to be primarily due to exposures and experiences within a generation rather than across generations

    Sobre la formación tomista del cardenal Zeferino González O.P. (1831-1894)

    Get PDF

    Effect of surfactant on PDLC films with and without permanent memory effect

    Get PDF
    Dissertação para obtenção do Grau de Mestre em Engenharia Química e BioquímicaThe main goal of this work is to optimize the performance of the PDLC films with the introduction of an additive, in this case the triton X100. The polymer matrix of the PDLC is based on monomers, such as Tri(ethylene glycol) dimethacrylate and poly(ethylene glycol) dimethacrylate with molecular weight of 875 which were thermal polymerized using α,α-azobisisobutyronitrile as initiator. Different aspects were investigated, such as the study of the dynamics of the transition ON/OFF state using a high-frequency alternate voltage and the attempt to minimize the liquid crystal anchorage force to the polymer matrix observed. The polymer morphology and the composites synthesized were analyzed by scanning electron microscopy. The PDLC films were also analyzed resorting to additional studies of differential scanning calorimetry, polarized optical microscopy and Fourier transform Infrared spectroscopy . Finally, the kinetic behavior of the PDLC films was studied. This part of the work was done with the goal to understand what was the impact of the increase amount of TX100 on the orientation and disorientation time of the LC molecules. Additionally, a fitting model was developed in order to describe the orientation and disorientation kinetic of the system. It was verified that the increase amount of TX100 modifies the initial anchorage force of the LC molecules to the polymeric matrix, decreasing it. This reflects on the increase of the permanent memory effect and decrease of the E90 of the PDLC films, verified also with the decrease of the average elastic constant, K, of the PDLC film. On this work, the best value for the permanent memory effect was 96% with an E90 of 2V/μm. However, this work also demonstrates that the kinetic of the system is independent of the amount of TX100, which means that the LC molecules orientate and disorientate at practically the same time with or without additive

    Growth performance, biochemical composition and sedimentation velocity of Tetraselmis sp. CTP4 under different salinities using low-cost lab- and pilot-scale systems

    Get PDF
    Biomass harvesting is one of the most expensive steps of the whole microalgal production pipeline. Therefore, the present work aimed to understand the effect of salinity on the growth performance, biochemical composition and sedimentation velocity of Tetraselmis sp. CTP4, in order to establish an effective low-cost pilot-scale harvesting system for this strain. At lab scale, similar growth performance was obtained in cultures grown at salinities of 5, 10 and 20 g L-1 NaCl. In addition, identical settling velocities (2.4-3.6 cm h-1) were observed on all salinities under study, regardless of the growth stage. However, higher salinities (20 g L-1) promoted a significant increase in lipid contents in this strain compared to when this microalga was cultivated at 5 or 10 g L-1 NaCl. At pilot-scale, cultures were cultivated semi-continuously in 2.5-m3 tubular photobioreactors, fed every four days, and stored in a 1-m3 harvesting tank. Upon a 24-hour settling step, natural sedimentation of the microalgal cells resulted in the removal of 93% of the culture medium in the form of a clear liquid containing only vestigial amounts of biomass (0.07 ± 0.02 g L-1 dry weight; DW). The remaining culture was recovered as a highly concentrated culture (19.53 ± 4.83 g L-1 DW) and wet microalgal paste (272.7 ± 18.5 g L-1 DW). Overall, this method provided an effective recovery of 97% of the total biomass, decreasing significantly the harvesting costs.Agência financiadora Portuguese national budget P2020 Foundation for Science and Technology (FCT) CMAR/Multi/04326/2013 ALGARED+ 1398 EP - INTERREG V-A Espana Portugal project ALGACO2 project 023310 COST Action 1408 - European Network for Bio-products FCT SFRH/BD/105541/2014info:eu-repo/semantics/publishedVersio

    Predicting growing stock volume of Eucalyptus plantations using 3-D point clouds derived from UAV imagery and ALS data

    Get PDF
    Estimating forest inventory variables is important in monitoring forest resources and mitigating climate change. In this respect, forest managers require flexible, non-destructive methods for estimating volume and biomass. High-resolution and low-cost remote sensing data are increasingly available to measure three-dimensional (3D) canopy structure and to model forest structural attributes. The main objective of this study was to evaluate and compare the individual tree volume estimates derived from high-density point clouds obtained from airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) in Eucalyptus spp. plantations. Object-based image analysis (OBIA) techniques were applied for individual tree crown (ITC) delineation. The ITC algorithm applied correctly detected and delineated 199 trees from ALS-derived data, while 192 trees were correctly identified using DAP-based point clouds acquired fromUnmannedAerialVehicles(UAV), representing accuracy levels of respectively 62% and 60%. Addressing volume modelling, non-linear regression fit based on individual tree height and individual crown area derived from the ITC provided the following results: Model E ciency (Mef) = 0.43 and 0.46, Root Mean Square Error (RMSE) = 0.030 m3 and 0.026 m3, rRMSE = 20.31% and 19.97%, and an approximately unbiased results (0.025 m3 and 0.0004 m3) using DAP and ALS-based estimations, respectively. No significant di erence was found between the observed value (field data) and volume estimation from ALS and DAP (p-value from t-test statistic = 0.99 and 0.98, respectively). The proposed approaches could also be used to estimate basal area or biomass stocks in Eucalyptus spp. plantationsinfo:eu-repo/semantics/publishedVersio

    Test beam operation of the CMS calorimeter trigger synchronization boards

    Get PDF
    The CMS experiment uses information from its electromagnetic and hadronic calorimeters and muon detectors to decide whether to readout the whole detector. For such a task to be successful, all trigger primitives pushed through the trigger decision tree must be flawlessly aligned in time for operation at 40 MHz. Both calorimeters in CMS use the Synchronization Link Board for this purpose. In this article we report on the results of tests of this board using realistic beam conditions, which demonstrate the soundness of the adopted architecture and synchronization principle

    Implications of climate change on the distribution and conservation of Cabo Verde endemic trees

    Get PDF
    Climate change is one of the most significant challenges to biodiversity conservation, particularly in dry tropical islands, such as the Cabo Verde archipelago where only three endemic tree taxa occur – Dracaena draco subsp. caboverdeana, Phoenix atlantica and Sideroxylon marginatum – all classified as threatened. The main goal of this study was to predict the possible shifts in the climatically suitable habitat ranges for Cabo Verdean endemic tree species under different climate change scenarios. We applied species distribution models (SDMs) to the available occurrence data, and projected the distribution of the three taxa for 2050 and 2080, according to the expected climate change scenarios. The best models were obtained using the Random Forest algorithm; they showed that, by 2080, the suitable habitat for Dracaena draco subsp. caboverdeana and Sideroxylon marginatum will have decreased by 28% and 34%, respectively; conversely, the suitable habitat will have increased by 59% for Phoenix atlantica, the taxon best adapted to arid conditions. Additionally, Santo Ant˜ao is the island where endangered trees are more encompassed by protected areas. Overall, this study contributed with new integrated data to support the design and implementation of a strategic plan to promote the conservation and ecological value of Cabo Verde endemic trees in this climatically vulnerable countryinfo:eu-repo/semantics/publishedVersio
    • …
    corecore