1,721,059 research outputs found
Interpolation theory and shell problems
No full textAbstractThe shell problem and its asymptotic are investigated. A connection between the asymptotic behavior of the shell energy and real interpolation theory is established. Although only the Koiter shells have been considered, the same procedure can be used for other models, such as Naghdi's one, for example
Singular perturbation and interpolation
No full textIt is well known that the rate of convergence of the solution u(epsilon) of a singular perturbed problem to the solution u of the unperturbed equation can be measured in terms of the ''smoothness'' of u; smoothness which, in turn, can be expressed in terms of linear interpolation theory. We want to prove a closer relationship between interpolation and singular perturbations, showing that interpolate spaces can be characterized by such a rate of convergence. Furthermore, with respect to a suitable (quite natural) definition of interpolation between convex sets, such a characterization holds true also in the framework of variational inequalities
From point cloud to parametric 3D model: polygonal modelling approach for optimising Scan to H-BIM and Scan to H-FEM processes
Full text link3D parametric modelling is a current and important research topic for the digitisation of cultural heritage in order to preserve the evolution and historical identity of an area over time; for this reason, cultural heritage assets must be subjected to continuous maintenance and monitoring, as well as valorisation and promotion. In addition, a considerable amount of these assets are often exposed to a high risk of damage caused by natural disasters and a poor state of care and neglect that leads to inevitable loss. In this context, in order to adopt all safeguarding and preservation measures in the field of CH, new sensors, digital acquisition technologies and suitable methodological approaches make it possible to create high-performance three-dimensional models, capable of increasing the detail and representation of particulars and enriching these models with heterogeneous information. However, such 3D models are often difficult to manage as they require very high processing and storage capacities. Therefore, it is necessary to define a suitable methodology that is capable of simplifying and optimising the three-dimensional models obtained from a photogrammetric or TLS approach, preserving their accuracy and metric rigour and, at the same time, performing efficiently in BIM (Building Information Modeling) and/or FEM (Finite Element Analysis) applications. The aim of this work is to identify a suitable process that is able, starting from a point cloud obtained by means of geomatic techniques, to generate three-dimensional surface models that are subsequently decimated and optimised according to the complexity of the case and the desired output. To achieve these objectives, a semi-automatic process is described that is capable of transforming a TIN (Triangulated Irregular Network) surface model into a quad-mesh polygonal model and then converting it into NURBS (Non-Uniform Rational Basis-Splines) for subsequent import into a BIM software or FEM solver for finite element calculations. As well as the optimisation requirements, this approach also pursues the objective of improving the quality of the final model, providing metrics (validated by means of suitable algorithms) and geometric resolution, resolving all the topological errors of the generated meshes (open surfaces, holes, edges, etc.), as well as optimising the computational aspects, sharing and interoperability between the different software and platforms used. The experimentation was carried out on two different case studies, and in particular a 14th-century church and a bronze statue, demonstrating the efficiency of the optimisation and management of complex geometries and validating, through a study on the repeatability of the approach considered, an efficient and accurate Scan to BIM and Scan to FEM process applied to existing cultural heritage
Upgrading from a Dual-chamber Pacemaker to a Cardiac Resynchronization Therapy Defibrillator in Situs Inversus Totalis with Dextrocardia Following Mitral Valve Replacement and Tricuspid Annuloplasty Using a Left-sided Approach
Full text linkA 71-year-old female patient was referred to our center to upgrade a dual-chamber pacemaker to a cardiac resynchronization therapy defibrillator (CRT-D) following the detection of worsened systolic function (ejection fraction:25%-30%) via transthoracic echocardiography. The patient had situs inversus totalis with dextrocardia. She had undergone mitral valve replacement and tricuspid annuloplasty in July 2019, with a concomitant left upper pulmonary lobectomy for neoplasm, detected at cardiac tomography incidentally. In January 2020, we performed an upgrade of the preexisting device to a CRT-D system because the patient developed heart failure, reduction in systolic function, and numerous nonsustained ventricular tachycardias. The right ventricular lead that had been previously implanted was extracted. To facilitate the intervention, we decided to flip the fluoroscopic image, obtained with a right-anterior oblique view, by 180° (right-left), creating the optical impression of a levocardial position. © 2021 Innovations in Cardiac Rhythm Managemen
Fibonacci expansions
No full textExpansions in the Golden ratio base have been studied since a pioneering paper of Rényi more than sixty years ago. We introduce closely related expansions of a new type, based on the Fibonacci sequence, and we show that in some sense they behave better
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