Encontrados 27 documentos, a visualizar página 1 de 3
Climate change, in the framework of the Constructal Law
Clausse, Marc; Meunier, Francis; Reis, A. Heitor; Bejan, AdrianHere we present a simple and transparent alternative to the complex models of earth’s thermal behaviour under time-changing conditions. We show the one-to-one relationship between changes in atmospheric properties and time-dependent changes in temperature and its distribution on earth. The model accounts for convection and radiation, thermal inertia and changes in albedo (ρ) and greenhouse factor (γ). The const...
Leaf shapes and venation patterns
Reis, A. HeitorWe present an analysis of leaf shapes and venation patterns based on a new assumption of the way how water flows in plants, together with the assumption that leaf shapes and leaf venation patterns have evolved in time such as to provide easier and easier access to its internal currents (Constructal Law). Then, by minimizing the global resistance to flow we anticipate the number of veins in relation to leaf shap...
Global Warming perspectives and new solutions- Editorial
Reis, A. Heitor; Salgado, RuiThe Editorial of The Special Issue of The International Journal of Global Warming, "Global Warming perspectives and new solutions"
and Development, from the Individual Researcher to research Empires
Reis, A. HeitorThis paper is dated: it was written at the time of the celebration of the 20 years of activity of the Évora Geophysics Centre (CGE). It comprises a brief appraisal of the evolution of scientific research in Europe and in the United States of America, together with a special reference to the development of the Portuguese scientific system. The size distribution of scientific teams in the whole system is address...
Laws of non-symmetric optimal flow structures, from the macro to the micro scale
Reis, A. HeitorMany natural systems and engineering processes occur in which a fluid invades a territory from one entry point (invasion), or conversely is expelled from the territory through an outlet (drainage). In any such situation an evolutionary flow structure develops that bridges the gap between the micro-scale (diffusion dominant) and the macroscale (convection dominant). The respiratory and circulatory systems of ani...
On the use of the Constructal Law to study Climate Change
Meunier, Francis; Clausse, Marc; Reis, A. Heitor; Bejan, AdrianA simple and transparent model, based on the constructal law, is used to study climate change as a response to changes in atmospheric properties (albedo-- and greenhouse factor –-). This model is first used to study the climate response to present changes in albedo and greenhouse factor. This allows comparing, in terms of energy imbalance and temperature, the climate change observed between 1880 and 2003 and ...
Using the constructal law to predict climate changes versus atmospheric properties
Meunier, F.; clausse, M.; Reis, A. Heitor; Bejan, A.A simple and transparent model, based on the constructal law, is used to study climate change as a response to changes in atmospheric properties (albedo-- and greenhouse factor –-). This model is first used to study the climate response to present changes in albedo and greenhouse factor. This allows comparing, in terms of energy imbalance and temperature, the climate change observed between 1880 and 2003 and ...
Use of sand beds of variable permeability in beach profile engineering
Reis, A. Heitor; Gama, CristinaHere we present a technique based on theoretical grounds for dealing with beachface dynamics in response to wave forcing. Previous work has provided a relationship involving mean sand grain size, wave height, and beachface slope for a broad range of Iribarren number. The key aspect of beach morphodynamics was shown to be the permeability of the sand bed, which may be correlated to sand grain size and sphericity...
“Simple model of resource exploitation”
Reis, A. HeitorHere we present a simple model of finite resource exploitation that is parameterized by initial cost ratio, a technologic and management index m accounting for the rise of the exploitation cost with decrease of resource amount, plus another index accounting for the avidity of the market to the resource. The analysis showed that the model captures essential features of finite resource exploitation, namely thos...
Coal and fuel burning effects on the atmosphere as mediated by the atmospheric ...
Reis, A. Heitor; Serrano, ClaudiaAbstract: Emissions into the atmosphere of Greenhouse Gases (GHGs) and particulate matter resulting from fossil fuel burning are considered to be the main anthropogenic forcing on the global climate. We show here that the external cyclic influences of cosmic origin that modulate the earth’s climate may either reinforce or mitigate the ‘local’ terrestrial forcings. Among the external influences is cosmic radiati...
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