Encontrados 16 documentos, a visualizar página 1 de 2
Application of 3D heat diffusion to detect embedded 3D empty cracks
Serra, C.; Tadeu, A.; Prata, J.; Simões, N.This paper presents a 3D boundary element model (BEM), formulated in the frequency domain, to simulate heat diffusion by conduction in the vicinity of 3D cracks. The model intends to contribute to the interpretation of infrared thermography (IRT) data results and to explore the features of this non-destructive testing technique (NDT) when it is used to detect and characterize defects. The defect is assumed to b...
Water productivity and crop yield in five chickpea varieties – how important is...
Silva, LL; Duarte, I; Simões, N; Lourenço, E; Chaves, MMChickpea (Cicer arietinum L.) is one of the most important pulse crops in the world as a source of protein for human consumption. In Mediterranean regions, chickpea is traditionally grown as a rainfed crop, thus highly dependent on rainfall. In this situation, supplemental irrigation may be applied. The objective of our study was to evaluate the improvement in crop yield and water productivity with supplemental...
Evaluating chickpea genotypes for abiotic stress tolerance
Duarte, I; Silva, LL; Simões, N; Imtiaz, M; Lourenço, E; Chaves, MMBeing a leguminous crop chickpea (Cicer arietinum L.) is important for the establishment of sustainable and economically viable farming systems. Chickpea is grown and consumed across five continents, making this crop more important in international markets than other food legumes. Adaptation trials of 15 accessions of chickpea, 13 from the ICARDA collection and 2 from the Portuguese national catalogue, took pla...
Leaf temperature and photosynthetic performance in chickpea
Pinheiro, C; Simões, N; Costa, M; Toureiro, A; Ribeiro, IC; Lourenço, ME; Silva, LL; Duarte, I; Chaves, MMThe responses of photosynthetic rate and leaf conductance to leaf temperature were evaluated in two contrasting chickpea genotypes (Elixir and FLIP03-46C) grown under field conditions (Elvas, Portugal). Photosynthetic performance was assayed with leaf temperatures ranging from 24ºC to 40º C under controlled VPD. Technical constraints and physiological implications are discussed.
Calibration and validation of SALTMED model under dry and wet year conditions u...
Silva, L.L.; Ragab, R.; Duarte, I.; Lourenço, E.; Simões, N.; Chaves, M.M.The SALTMED model is one of the few available generic models that can be used to simulate crop growth with an integrated approach that accounts for water, crop, soil, and field management. It is a physically based model using the well-known water and solute transport, evapotranspiration, and water uptake equations. In this paper, the model simulated chickpea growth under different irrigation regimes and a Medit...
Conduction and convection phenomena through a slab with thermal heterogeneities
Tadeu, A.; Simões, N.This paper addresses the computation of the three-dimensional transient heat transfer through a layered solid and/or fluid formation containing irregular inclusions. The use of appropriate Green's functions for a flat layer formation in a boundary element method formulation avoids the discretization of the layer interface boundaries. ; http://www.sciencedirect.com/science/article/B6TYC-4K9C6V7-2/1/96b8b86fba...
A dinâmica da produtividade do trabalho em Portugal
Simões, N. N.resumem-se dinâmicas bastante diversificadas. No conjunto das mais importantes inscrevem-se as relacionadas com a eficiência interna de cada empresa, com a mobilidade dos recursos entre unidades com níveis de produtividade distintos bem como a permanente entrada e saída de empresas do agregado em análise. Apenas a partir do momento em que dispomos de dados recolhidos ao nível da empresa é possível deduzir o pap...
Labor demand, productivity and business cycle: evidence from Portuguese large f...
Simões, N. N.What determines the cyclical behaviour of labor productivity? This article considers intra firm and inter firm explanations for the correlation between labor productivity and aggregate shocks. From a set of 2100 Portuguese firms with more than 100 workers, between 1995 and 1999, we found that: (1) aggregate labor productivity was procyclical, although more than half of the firms revealed countercyclical product...
Response of clamped structural slabs subjected to a dynamic point load via BEM
António, J.; Tadeu, A.; Simões, N.This work computes the response of clamped slabs when subjected to spatially sinusoidal harmonic line loads via the Boundary Element Method (BEM). The formulation uses 2.5D Green's functions for the steady state response of a homogeneous three-dimensional free solid layer formation of infinite extent, proposed earlier by the authors. The inclusion of these Green's functions in the BEM formulation avoids the dis...
Effect of airflow rate on yields of Steinernema carpocapse Az 20 in liquid cult...
Neves, J. M.; Teixeira, J. A.; Simões, N.; Mota, M.Maximization of the contact between males and females is a key factor in the production of the nematode Steinernema carpocapsae in a bioreactor. The influence of the airflow rate in male and female distribution and mass production in an external-loop bioreactor with a deceleration zone was studied. When operating at an airflow rate of 0.05 vvm, a high retention of females in the deceleration zone of the bioreac...
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