5,082 research outputs found
The Argyris isogeometric space on unstructured multi-patch planar domains
No full textMulti-patch spline parametrizations are used in geometric design and
isogeometric analysis to represent complex domains. We deal with a particular
class of planar multi-patch spline parametrizations called
analysis-suitable (AS-) multi-patch parametrizations (Collin,
Sangalli, Takacs; CAGD, 2016). This class of parametrizations has to satisfy
specific geometric continuity constraints, and is of importance since it allows
to construct, on the multi-patch domain, isogeometric spaces with optimal
approximation properties. It was demonstrated in (Kapl, Sangalli, Takacs; CAD,
2018) that AS- multi-patch parametrizations are suitable for modeling
complex planar multi-patch domains.
In this work, we construct a basis, and an associated dual basis, for a
specific isogeometric spline space over a given AS-
multi-patch parametrization. We call the space the Argyris
isogeometric space, since it is across interfaces and at all
vertices and generalizes the idea of Argyris finite elements to tensor-product
splines. The considered space is a subspace of the entire
isogeometric space , which maintains the reproduction
properties of traces and normal derivatives along the interfaces. Moreover, it
reproduces all derivatives up to second order at the vertices. In contrast to
, the dimension of does not depend on the domain
parametrization, and admits a basis and dual basis which possess
a simple explicit representation and local support.
We conclude the paper with some numerical experiments, which exhibit the
optimal approximation order of the Argyris isogeometric space and
demonstrate the applicability of our approach for isogeometric analysis
A family of C-1 quadrilateral finite elements
No full textWe present a novel family of C-1 quadrilateral finite elements, which define global C-1 spaces over a general quadrilateral mesh with vertices of arbitrary valency. The elements extend the construction by Brenner and Sung (J. Sci. Comput. 22(1-3), 83-118, 2005), which is based on polynomial elements of tensor-product degree p >= 6, to all degrees p >= 3. The proposed C-1 quadrilateral is based upon the construction of multi-patch C-1 isogeometric spaces developed in Kapl et al. (Comput. Aided Geometr. Des. 69, 55-75 2019). The quadrilateral elements possess similar degrees of freedom as the classical Argyris triangles, developed in Argyris et al. (Aeronaut. J. 72(692), 701-709 1968). Just as for the Argyris triangle, we additionally impose C-2 continuity at the vertices. In contrast to Kapl et al. (Comput. Aided Geometr. Des. 69, 55-75 2019), in this paper, we concentrate on quadrilateral finite elements, which significantly simplifies the construction. We present macro-element constructions, extending the elements in Brenner and Sung (J. Sci. Comput. 22(1-3), 83-118 2005), for polynomial degrees p = 3 and p = 4 by employing a splitting into 3 x 3 or 2 x 2 polynomial pieces, respectively. We moreover provide approximation error bounds in L-infinity, L-2, H-1 and H-2 for the piecewise-polynomial macro-element constructions of degree p is an element of{3,4} and polynomial elements of degree p >= 5. Since the elements locally reproduce polynomials of total degree p, the approximation orders are optimal with respect to the mesh size. Note that the proposed construction combines the possibility for spline refinement (equivalent to a regular splitting of quadrilateral finite elements) as in Kapl et al. (Comput. Aided Geometr. Des. 69, 55-75 30) with the purely local description of the finite element space and basis as in Brenner and Sung (J. Sci. Comput. 22(1-3), 83-118 2005). In addition, we describe the construction of a simple, local basis and give for p is an element of{3,4,5} explicit formulas for the Bezier or B-spline coefficients of the basis functions. Numerical experiments by solving the biharmonic equation demonstrate the potential of the proposed C1 quadrilateral finite element for the numerical analysis of fourth order problems, also indicating that (for p = 5) the proposed element performs comparable or in general even better than the Argyris triangle with respect to the number of degrees of freedom
Contro la funzionalizzazione della contrattazione collettiva. Riflessioni sul pensiero di Mario Rusciano
No full textL'autore riflette sul pensiero di Mario Rusciano in punto di funzionalizzazione della contrattazione collettiva.The author reflects on the thought of Mario Rusciano in relation to the subject of the functionalisation of collective bargaining
Isogeometric analysis with functions on planar, unstructured quadrilateral meshes
No full textIn the context of isogeometric analysis, globally C1 isogeometric spaces over unstructured quadrilateral meshes allow the direct solution of fourth order partial differential equations on complex geometries via their Galerkin discretization. The design of such smooth spaces has been intensively studied in the last five years, in particular for the case of planar domains, and is still task of current research. In this paper, we first give a short survey of the developed methods and especially focus on the approach [28]. There, the construction of a specific C1 isogeometric spline space for the class of so-called analysis-suitable G1 multi-patch parametrizations is presented. This particular class of parameterizations comprises exactly those multi-patch geometries, which ensure the design of C1 spaces with optimal approximation properties, and allows the representation of complex planar multi-patch domains. We present known results in a coherent framework, and also extend the construction to parametrizations that are not analysis-suitable G1 by allowing higher-degree splines in the neighborhood of the extraordinary vertices and edges. Finally, we present numerical tests that illustrate the behavior of the proposed method on representative examples
Isogeometric analysis for multi-patch structured Kirchhoff–Love shells
No full textWe present an isogeometric method for Kirchhoff–Love shell analysis of shell structures with geometries composed of multiple patches and which possibly possess extraordinary vertices, i.e. vertices with a valency different to four. The proposed isogeometric shell discretisation is based on the one hand on the approximation of the mid-surface by a particular class of multi-patch surfaces, called analysis-suitable G1 (Collin et al., 2016), and on the other hand on the use of the globally C1-smooth isogeometric multi-patch spline space (Farahat et al., 2023). We use our developed technique within an isogeometric Kirchhoff–Love shell formulation (Kiendl et al., 2009) to study linear and non-linear shell problems on multi-patch structures. Thereby, the numerical results show the great potential of our method for efficient shell analysis of geometrically complex multi-patch structures which cannot be modelled without the use of extraordinary vertices.Funding Information: The authors wish to thank the anonymous reviewers for their comments that helped to improve the paper. A. Farahat and M. Kapl have been supported by the Austrian Science Fund (FWF) through the project P 33023-N. H.M. Verhelst is grateful for the funding from Delft University of Technology. J. Kiendl has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No 864482). Additionally, the authors are grateful for the support from the developers of the Geometry + Simulation Modules, in particular from A. Mantzaflaris (Inria Sophia Antipolis-Méditerranée). Funding Information: The authors wish to thank the anonymous reviewers for their comments that helped to improve the paper. A. Farahat and M. Kapl have been supported by the Austrian Science Fund (FWF) through the project P 33023-N . H.M. Verhelst is grateful for the funding from Delft University of Technology . J. Kiendl has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 864482 ). Additionally, the authors are grateful for the support from the developers of the Geometry + Simulation Modules, in particular from A. Mantzaflaris (Inria Sophia Antipolis-Méditerranée).Numerical AnalysisShip Hydromechanics and Structure
Il diritto penale nel canone di Mario Romano
No full textThis paper deals with the extension and the extraordinary scientific value of the works written by a great Master in Criminal Law, such as Mario Romano. The Author briefly presents some of the most relevant contributions given by Professor Mario Romano to the Criminal Science, first of all his "Commentario sistematico del codice penale" (Systematic Commentary on the penal code), a unique work. Finally, the paper talks about some topics which have been developed inside the work "Studi in onore di Mario Romano" (Studies in Honour of Mario Romano)
Introduzione, a Mario Tobino, Il Clandestino
No full textL'introduzione presenta il libro più ambizioso di Mario Tobino, Il Clandestino, dedicato al racconto della sua esperienza con i gruppi clandestini della Resistenza Viareggina, libro con cui l'autore vinse il Premio Strega, nel 1962, imponendosi all'attenzione del grande pubblico dopo il successo dei libri manicomiali. Una nuova edizione in cui Paola Italia valorizza i materiali inediti dell'Archivio Tobino conservato presso l'Archivio Contemporaneo A. Bonsanti del Gabinetto GP Vieusseux di Firenze,Paola Italia presents an Introduction to the new edtion of Il Clandestino, the most ambitious of Mario Tobino's novels, dedicated to the story of his experience with the groups of the Tuscan Resistance when he was a psichiatric doctor ar Lucca. With this book the author won the Strega Prize, in 1962, attracting the attention of a wide public after the success of his psichiatric books. A new edition where Paola Italia enhances the unpublished material of Tobino Archive preserved in A. Bonsanti Contemporary Archive of G.P. Vieusseux Cabinet of Florence
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