Semi-implicit finite strain constitutive integration and mixed strain/stress control based on intermediate configurations

A new semi-implicit stress integration algorithm for finite strain plasticity (compatible with hyperelas- ticity) is introduced. Its most distinctive feature is the use of different parameterizations of equilibrium and reference configurations. Rotation terms (nonlinear trigonometric functions) are integrated explicitly and correspond to a change in the reference configuration. In contrast, relative Green–Lagrange strains (which are quadratic in terms of displacements) represent the equilibrium configuration implicitly. In addition, the adequacy of several objective stress rates in the semi-implicit context is studied. We para- metrize both reference and equilibrium configurations, in contrast with the so-called objective stress integration algorithms which use coinciding configurations. A single constitutive framework provides quantities needed by common discretization schemes. This is computationally convenient and robust, as all elements only need to provide pre-established quantities irrespectively of the constitutive model. In this work, mixed strain/stress control is used, as well as our smoothing algorithm for the complemen- tarity condition. Exceptional time-step robustness is achieved in elasto-plastic problems: often fewer than one-tenth of the typical number of time increments can be used with a quantifiable effect in accuracy. The proposed algorithm is general: all hyperelastic models and all classical elasto-plastic models can be employed. Plane-stress, Shell and 3D examples are used to illustrate the new algorithm. Both isotropic and anisotropic behavior is presented in elasto-plastic and hyperelastic examples.

Above ground biomass functions with vegetation indices for multiple use systems of two evergreen oaks

Remote sensing is a promising approach for above ground biomass estimation, as forest parameters can be obtained indirectly. The analysis in space and time is quite straight forward due to the flexibility of the method to determine forest crown parameters with remote sensing. It can be used to evaluate and monitoring for example the development of a forest area in time and the impact of disturbances, such as silvicultural practices or deforestation. The vegetation indices, which condense data in a quantitative numeric manner, have been used to estimate several forest parameters, such as the volume, basal area and above ground biomass. The objective of this study was the development of allometric functions to estimate above ground biomass using vegetation indices as independent variables. The vegetation indices used were the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Simple Ratio (SR) and Soil-Adjusted Vegetation Index (SAVI). QuickBird satellite data, with 0.70 m of spatial resolution, was orthorectified, geometrically and atmospheric corrected, and the digital number were converted to top of atmosphere reflectance (ToA). Forest inventory data and published allometric functions at tree level were used to estimate above ground biomass per plot. Linear functions were fitted for the monospecies and multispecies stands of two evergreen oaks (Quercus suber and Quercus rotundifolia) in multiple use systems, montados. The allometric above ground biomass functions were fitted considering the mean and the median of each vegetation index per grid as independent variable. Species composition as a dummy variable was also considered as an independent variable. The linear functions with better performance are those with mean NDVI or mean SR as independent variable. Noteworthy is that the two better functions for monospecies cork oak stands have median NDVI or median SR as independent variable. When species composition dummy variables are included in the function (with stepwise regression) the best model has median NDVI as independent variable. The vegetation indices with the worse model performance were EVI and SAVI.

Adesão a recomendações de ingestão de água, em idosos: preditores psicossociais e efeitos da comunicação de informação com uso de âncoras de referência

Sendo os idosos um grupo de risco face a desidratação, torna-se particularmente relevante desenvolver estratégias eficazes de comunicação em saúde para o incremento da adesão a recomendações médicas para ingestão de água. Com este objetivo procurámos avaliar os efeitos da comunicação de uma recomendação, com recurso a uma referência familiar (e.g. garrafa de 1.5 Litros) na qual os idosos pudessem “ancorar” o seu julgamento e decisão de adesão à recomendação, com base numa mais eficaz compreensão de informação de quantidade. Dos 70 idosos que participaram no estudo, apenas 56 foram considerados na análise, por cumprirem os critérios de inclusão na amostra. Esta amostra incluiu idosos autónomos, não institucionalizados, responsáveis pelas suas escolhas alimentares e com indicadores de hidratação aceitáveis. Os resultados mostraram que numa condição com âncora familiar (mas não na condição sem), a adesão associada ao próprio nível de consumo existente, do idoso aumentou após a recomendação. Análises adicionais identificaram as crenças face à água e as suas várias funções, como um preditor psicossocial positivo da adesão, o mesmo não acontecendo com atitudes face à água, evitamento de informação alimentar negativa e numeracia; Abstract: Being the elderly a risk group with regard to dehydration it is necessary to develop effective health communication strategies to increase adherence to health recommendations concerning water intake. Accordingly, we aimed to assess the effects of communicating a recommendation with the addition of a familiar reference (e.g. bottle of 1.5 Liters) in which the elderly could anchor their judgment and decision making to adhere to the recommendation, based on a better comprehension of the quantified information presented. From the 70 older adults that have participated in the study, only 56 were considered in the analysis, for fulfilling the sample inclusion criteria. This sample included older adults considered to be autonomous, non-institutionalized, responsible for their good choices and with acceptable hydration levels. Results showed that in a condition with a familiar anchor (but not in a condition without) the adherence in line with the elderly own current consumption level, increased after the recommendation. Additional analysis identified beliefs concerning water and its various functions as a positive psychosocial predictor of adherence, the same not happening for attitudes towards water, avoidance of negative food information and numeracy.