394 research outputs found
Koiter analysis of folded structures using a corotational approach
No full textAbstractThe paper deals with geometrically nonlinear finite element analysis of folded-plate and shell structures. A Koiter asymptotic approach is proposed, based on the reuse of a linear element in the nonlinear context through a corotational formulation.The corotational approach represents a simple and effective way to satisfy the basic requirement of Koiter analysis, i.e. full objectivity in the finite element modeling. In fact, starting simply from a suitable linear finite element and implementing the corotational algebra proposed in Garcea et al. (2009), Zagari (2009) lead to objective explicit expressions for the first four variations of the strain energy which are needed by asymptotic analysis.The shell element used here is the flat shell quadrangular element with 4 nodes and 6 dofs per node proposed in Madeo et al. (2012) and called MISS-4: a mixed element, based on the Reissner–Mindlin plate theory, with an Allman-like quadratic interpolation for displacements and an equilibrated isostatic interpolation for the stress resultants. The element is free from locking and spurious zero-energy modes, so it appears a suitable candidate for nonlinear corotational analysis.The results of the numerical validation show the effectiveness and accuracy of the proposed approach, and its excellent overall robustness for both mono- and multi-modal buckling problems, also in the presence of strong nonlinear pre-critical behavior
Una memoria agricola in un paesaggio low cost
No full textL'esperienza della trasformazione del paesaggio agrario tradizionale in un parco urbano partecipato a basso costo. Nella sorprendente Palermo, una città complessa, dove un paesaggio drammatico combatte giorno dopo giorno contro una città contemporanea di pietra e di cemento, un giardino nascosto di Opuntia viene scoperto ancora una volta dopo decenni di oblio, grazie ak lavoro e alla incessante promozione fatta da un gruppo di cittadini, studenti, professori e volontari
Il Paesaggio come sfida. Il progetto.
No full textRaccolta di contributi di autori internazionali e nazionali sul ruolo politico del progetto di paesaggio come motore per i processi di rigenerazione dell'habitat, prodotti per il convegno internazionale del 3 e 4 marzo 2016 'Il paesaggio come sfida', presso la facoltà di Architettura di Roma Sapienza
Gastric cancer: who is at risk?
No full textGastric cancer is a multifactorial disease. Helicobacter pylori infection, host genetic factors and dietetic factors play an important role in the development of gastric cancer. Individuals with a positive family history of gastric cancer and/or pro-inflammatory polymorphisms of the interleukin-1 and tumor necrosis factor A genes infected by H. pylori virulent strains (cagA-, vacA s1-, vacA m1- and babA2-positive) have the highest risk of gastric cancer development. Diets rich in salted and smoked food and poor in fresh fruit and vegetables favor gastric carcinogenesis. Genetic combined with bacterial and host genotyping may allow for the identification of patients at high risk of gastric cancer who can benefit from preventive eradication therapy. Copyright (c) 2004 S. Karger AG, Basel
One- or two-week triple therapy for Helicobacter pylori: questions of efficacy and inclusion of a dual therapy treatment arm
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