Search results for "Tropic"
showing 10 items of 1375 documents
“L’intrusione marina negli acquiferi carbonatici costieri della Sicilia Sud-Orientale”
2007
Computational modelling of brittle failure in polycrystalline materials using cohesive-frictional grain-boundary elements
2014
A 3D grain-level formulation for the study of brittle failure in polycrystalline microstructures is presented. The microstructure is represented as a Voronoi tessellation and the boundary element method is used to model each crystal of the aggregate. The continuity of the aggregate is enforced through suitable conditions at the intergranular interfaces. The grain-boundary model takes into account the onset and evolution of damage by means of an irreversible linear cohesive law, able to address mixed-mode failure conditions. Upon interface failure, a non-linear frictional contact analysis is introduced for addressing the contact between micro-crack surfaces. An incremental-iterative algorith…
Vibration-based identification of mechanical properties of orthotropic arbitrarily shaped plates: Numerical and experimental assessment
2018
Abstract An innovative procedure is introduced for the identification of the mechanical parameters of orthotropic plates of arbitrary shape, under various boundary conditions, based on vibration data. The method employs a combination of a convenient Rayleigh-Ritz approach and Particle-Swarm Optimization to estimate elastic constants of the orthotropic material in a straightforward manner, without requiring computationally demanding iterative Finite Element analyses. Specifically, the pb-2 Rayleigh-Ritz procedure is extended and applied to deal with orthotropic plates, simplifying the approach to more easily treat generic plate shapes, taking advantage of the Green's theorem. The method is t…
Dynamic response of equivalent orthotropic plate model for stiffened plate: numerical-experimental assessment
2017
Abstract Over the last two decades, homogenization-based modeling techniques have attracted considerable attention. In fact, through these methods, structures such as corrugated or stiffened plates, commonly referred to as structurally orthotropic plates, can be approximately studied as equivalent flat plates with orthotropic behavior. Specifically, these homogenization techniques allow for the direct determination of the equivalent flexural and torsional rigidities which appear in the governing equation for the deflection of the equivalent orthotropic plate. It is worth noting that, the determined equivalent material properties retain the dependence on the geometric parameters of the origi…
Noise Filtering Using Edge-Driven Adaptive Anisotropic Diffusion
2008
This paper presents a method aimed to noise removal in MRI (Magnetic Resonance Imaging). We propose an improvement of Perona and Malik's anisotropic diffusion filter. In our schema, the diffusion equation of the filter has been modified to take into account the edges direction, This allows the filter to blur uniform areas, while it better preserves the edges. Both quantitative and qualitative evaluation is presented and the results are compared with other methods.
Il Paesaggio antropico: la Sicilia da Idrisi a Brandi
2011
Ricostruire una città, reinventare un'odonomastica
2014
La vicenda della ricostruzione di Gibellina, dopo il terremoto del 1968, è molto nota e ha costituito un caso di studio nazionale e internazionale. La new town che venne edificata con il nome di Gibellina Nuova, a venti chilometri dalla Vecchia, seguì criteri topografici profondamente diversi, idonei non soltanto a garantire la sicurezza dell’abitato, ma soprattutto a proporre un modello utopico di città. La ricostruzione fu anche il movente di un sisma odonomastico che ha ulteriormente disorientato gli abitanti superstiti. Spariti e non più riorganizzati i quartieri, crollate e non più ricostruite le chiese, gli antichi monumenti sostituiti da altri dai nomi estranei e non memorizzabili (e…
Existence of two positive solutions for anisotropic nonlinear elliptic equations
2021
This paper deals with the existence of nontrivial solutions for a class of nonlinear elliptic equations driven by an anisotropic Laplacian operator. In particular, the existence of two nontrivial solutions is obtained, adapting a two critical point results to a suitable functional framework that involves the anisotropic Sobolev spaces.
Louseborne relapsing fever in young migrants, sicily, Italy, july-september 2015
2016
To the Editor: During the early 20th century, at the end of World War I, and during World War II, louseborne relapsing fever (LBRF) caused by Borrelia recurrentis was a major public health problem, especially in eastern Europe and northern Africa (1,2). Currently, poor living conditions, famine, war, and refugee camps are major risk factors for epidemics of LBRF in resource-poor countries, such as those in the Horn of Africa (3,4). Increased migration from resource-poor countries and war/violence create new routes for spread of vectorborne diseases. Recently, several cases of LBRF have been reported among asylum seekers from Eritrea in the Netherlands, Switzerland, and Germany (5–8). All of…
Evolutionary processes in the emergence and recent spread of the syphilis agent, Treponema pallidum
2022
Abstract The incidence of syphilis has risen worldwide in the last decade in spite of being an easily treated infection. The causative agent of this sexually transmitted disease is the bacterium Treponema pallidum subspecies pallidum (TPA), very closely related to subsp. pertenue (TPE) and endemicum (TEN), responsible for the human treponematoses yaws and bejel, respectively. Although much focus has been placed on the question of the spatial and temporary origins of TPA, the processes driving the evolution and epidemiological spread of TPA since its divergence from TPE and TEN are not well understood. Here, we investigate the effects of recombination and selection as forces of genetic diver…