216 research outputs found
Algorithms for the implementation of adaptive isogeometric methods using hierarchical B-splines
No full textIn this article we introduce all the ingredients to develop adaptive isogeometric methods based on hierarchical B-splines. In particular, we give precise definitions of local refinement and coarsening that, unlike previously existing methods, can be understood as the inverse of each other. We also define simple and intuitive data structures for the implementation of hierarchical B-splines, and algorithms for refinement and coarsening that take advantage of local information. We complete the paper with some simple numerical tests to show the performance of the data structures and algorithms, that have been implemented in the open-source Octave/Matlab code GeoPDEs.Fil: Garau, Eduardo Mario. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Vázquez, Rafael. École Polytechnique Fédérale de Lausanne; Suiza. Consiglio Nazionale delle Ricerche. Istituto di Matematica Applicata e Tecnologie Informatiche; Itali
Adaptive control of local errors for elliptic problems using weighted Sobolev norms
No full textWe develop an a posteriori error estimator which focuses on the local H1 error on a region of interest. The estimator bounds a weighted Sobolev norm of the error and is efficient up to oscillation terms. The new idea is very simple and applies to a large class of problems. An adaptive method guided by this estimator is implemented and compared to other local estimators, showing an excellent performance. © 2016 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 1266–1282, 2017.Fil: Garau, Eduardo Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química; ArgentinaFil: Morin, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentin
Convergence of adaptive finite element methods for eigenvalue problems
No full textIn this paper we prove convergence of adaptive finite element methods for second-order elliptic eigenvalue problems. We consider Lagrange finite elements of any degree and prove convergence for simple as well as multiple eigenvalues under a minimal refinement of marked elements, for all reasonable marking strategies, and starting from any initial triangulation.Fil: Garau, Eduardo Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Matemática Aplicada del Litoral. Universidad Nacional del Litoral. Instituto de Matemática Aplicada del Litoral; ArgentinaFil: Morin, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Matemática Aplicada del Litoral. Universidad Nacional del Litoral. Instituto de Matemática Aplicada del Litoral; ArgentinaFil: Zuppa, Carlos. Universidad Nacional de San Luis; Argentin
Energy analysis of the human gait: A comparison between natural gait and with jumping stilts
No full textThe purpose of this work is to evaluate the mechanical energy exchange during the gait cycle of a subject equipped with energy storage devices (jumping stilts). For comparison, the same evaluation was carried out in a gait cycle with no jumping stilts (natural gait). First, a video of the motion was recorded, then the video frames were post-processed to obtain the sagittal plane trajectories of eleven markers (geometric points) placed onto the subject and finally a numerical code was developed to build up a multi-bodies model able to compute the mechanical energy during the gait. Further, the results from the multi-bodies model were compared with those from a simplified model based on the motion of the centre of mass of the subject
I Capitoli di Grazia nella Sardegna medioevale e moderna: spunti per un’indagine archivistica
No full textThe essay retraces the long path of the studies conducted by Sardinian historians on
“Chapters Grace”, old agreements signed between feudal lords and their vassals from
the Fifteenth century, reaching, in the second part, the recovery and then the census,
of the relevant documentation retained in the public records of Sardinia. The work
is completed with two summary tables in which the author provide an account of
archival sources so far investigated, in compliance with the administrative districts
and their feudal reality of the island between the Fifteenth and Eighteenth centuries
On Quasi-Interpolation Operators in Spline Spaces
No full textWe propose the construction of a class of L2 stable quasi-interpolationoperators onto the space of splines on tensor-product meshes, in any space dimension. The estimate we propose is robust with respect to knot repetition and to knot ?vicinity? (up to p+1 knots), so it applies to the most general scenario in which the B-spline functions are known to be well defined.Fil: Buffa, Annalisa. Consiglio Nazionale delle Ricerche. Istituto di Matematica Applicata e Tecnologie Informatiche; ItaliaFil: Garau, Eduardo Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Matemática Aplicada del Litoral. Universidad Nacional del Litoral. Instituto de Matemática Aplicada del Litoral; ArgentinaFil: Giannelli, Carlotta. Università degli Studi di Firenze; ItaliaFil: Sangalli, Giancarlo. Consiglio Nazionale delle Ricerche. Istituto di Matematica Applicata e Tecnologie Informatiche; Itali
Prove di lotta contro l'oidio del carciofo nel biennio 1994-95 in Sardegna
No full textTWO YEARS OF FIELD TRIALS AGAINST POWDERY MILDEW OF ARTICHOKE IN SARDINIA
The results of field trials carried out in Sardinia against Leveillula taurica (Lév.) Arn. f. sp. Cynarae Jacz., the causal agent of powdery mildew of Artichoke (Cynara scolymus L.), are reported. The new triazole fungicide Bromuconazole was compared with other chemicals (Hexaconazole, Penconazole, Triadimefon, Triadimenol and Pyrazophos) used against this disease.Most fungicides, with the exception of pyrazophos, were effective in preventing or blocking the diesease
Quasi-optimal convergence rate of an AFEM for quasi-linear problems of monotone type
No full textWe prove the quasi-optimal convergence of a standard adaptive finite element method (AFEM) for a class of nonlinear elliptic second-order equations of monotone type. The adaptive algorithm is based on residual-type a posteriori error estimators and Dörfler's strategy is assumed for marking. We first prove a contraction property for a suitable definition of total error, analogous to the one used by Diening and Kreuzer (2008) and equivalent to the total error defined by Cascón et. al. (2008). This contraction implies linear convergence of the discrete solutions to the exact solution in the usual H1 Sobolev norm. Secondly, we use this contraction to derive the optimal complexity of the AFEM. The results are based on ideas from Diening and Kreuzer and extend the theory from Cascón et. al. to a class of nonlinear problems which stem from strongly monotone and LipschitzFil: Garau, Eduardo Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Matemática Aplicada del Litoral. Universidad Nacional del Litoral. Instituto de Matemática Aplicada del Litoral; ArgentinaFil: Morin, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Matemática Aplicada del Litoral. Universidad Nacional del Litoral. Instituto de Matemática Aplicada del Litoral; ArgentinaFil: Zuppa, Carlos. Universidad Nacional de San Luis; Argentin
On the kinematics of the gait with jumping stilts.
No full textThis work deals with the kinematic analysis of the gait cycle of a subject fitted with jumping stilts. A motion capture analysis was conducted by recording the trajectory of the subject's free-flying hoof during a complete gait cycle. A six-degrees of freedom serial chain was used to simulate the subject's legs kinematic on the sagittal plane. The positions and velocities of the subject's free-flying hoof obtained from the photo-frames of the video and from the kinematic model was used to validate the model
UP SCHOOL: Introduction of pervasive learning technologies to enhance classic educational models
No full textWith the continuous development of new technologies that have been naturally integrated in the daily activities of children, it becomes necessary to include them in the educational programs, in order to enhance the children‘s learning with tools they are already familiar with. In this paper, we present a case study realized by UP SCHOOL, a new Italian Primary School that introduces a novel educational model, designed around the children to favor their learning. In particular, we will focus on the learning technologies employed in this project, on the motivation that led to their inclusion in UP SCHOOL, and on how they have been designed and adapted for the use by young children in a learning environment
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