741 research outputs found
INIBITORI DI PCSK9 : ESPERTI A CONFRONTO G. Iannuzzo: L’esperto di ultrasuoni
No full textConvegno Società Italiana per lo studio dell'Aterosclerosi (sezione Campania
A novel approach to model differential settlements and crack patterns in masonry structures
No full textThe present paper introduces a novel methodology for accurately modelling differential settlements beneath the foundations of masonry structures and the resulting crack patterns. In contrast to standard strategies, which typically impose predefined settlements at the structure's base, the proposed approach directly accounts for the soil–structure interaction by coupling the mechanical responses of masonry and soil. Specifically, the mechanical behaviour of the masonry is accurately modelled using an elastic no-tension approach, while the soil is represented as an elastic half-plane. The solution to the coupled mechanical problem, satisfying both equilibrium and compatibility conditions, is obtained through an iterative optimisation-based procedure. Several 2D numerical applications, considering different geometries and loading conditions, are provided to demonstrate the proposed procedure's effectiveness and performance and highlight its potential
Rocking of a rigid block freestanding on a flat pedestal
No full textThe seismic protection of objects contained within Museums is a topic of great interest, especially with reference to how they are displayed or stored. This problem is the same as that of a large class of non-structural components, such as mechanical and electrical hospital and laboratory equipment that could lose their functionality because of earthquakes. Statues and ceramics simply supported on the floor represent a significant set of case. In some cases, like the Bronzes of Riace, isolation systems have been developed. However, in general museum exhibits are not equipped with devices capable of mitigating the oscillations induced by possible earthquakes. The case study of a marble statue placed on a freestanding squat rigid pedestal is examined. The system of algebraic differential equations governing the problem has been derived and included in an ad-hoc numerical procedure. It is shown that the insertion of a squat rigid body with low frictional resistance at the lower interface with the floor significantly reduces the amplitude of the rocking response. The numerical analysis performed can be a tool to help in the choice of the optimal friction values in the surfaces of the flat block, designed as a simple isolation system
Nonlinear dynamics of a wind turbine tower
No full textThe recent diffusion of wind turbines has evidenced problems about their vulnerability in different site conditions, as shown by recent collapse of wind towers after severe actions. The analysis of structures subjected to variable actions can be carried out by means of several methods with different levels of accuracy, among which the nonlinear dynamics is generally recognized as the most reliable one. This paper develops a numerical procedure to obtain approximate solutions for rigid-plastic response of structures subjected to base harmonic pulse. The model is applied to a wind turbine tower subjected to inertia forces generated by an harmonic ground acceleration, in which the failure is assumed depending on the formation of shear hinges. The approach presents the advantages of rigid-plastic procedures, in particular an efficient representation of the post-elastic behaviour of the structure, low computational competence and limited number of mechanical parameters
Aterosclerosi preclinica
No full textl'intervento in fase precoce dell malattia aterosclerotica è essenziale per la sua prevenzione ed è basato su identificazione di fattori di rischio cardiovascolari e su individuazione di cambiamenti morfologici e funzionali precoci della parete arterios
Masonry differential settlements analysis including the soil
No full textIn the present paper, a novel approach is proposed to investigate the effects of differential settlements on masonry structures modelling the construction as a no-tension material, and, more importantly, directly considering the soil-structure interaction with an explicit modelling of the unilateral contact between soil and structure. The soil behaviour is included by a boundary integral approach, thus avoiding mesh discretisation issues. Some numerical examples will be shown to demonstrate the efficiency of the procedure
Rocking behaviour of freestanding objects
No full textThe safeguard of museum exhibits like vases and statues, laboratory equipments, storage tanks, or even tall buildings and other structural elements subjected to earthquake and in general to time-dependent forces has been in the last years a topic focus. The classical mechanical problem of the motions of rigid objects simply supported on a base plane, developed in the first year of sixties, thanks to the seminal paper by Housner on the inverted pendulum, can be now take advance due to the development of calculation tools. In some cases the quality of motion can be determined varying the material parameters involved. This is a strong tool to reduce vulnerability, especially when rocking motion should be avoided and sliding motion is welcome, as in the case of artistic heritage. This paper focuses the attention on this last problem, common to a large class of both non-structural and structural elements that can lose their functionality because of earthquake motions. The results of a numerical modelling of sliding and rocking motion in presence of both different excitations and mechanical parameters are presented and compared with experimental data performed by the authors. The results developed are in good agreement with the laboratory tests and this assures the reliability of both the analytical procedure and the determination of the parameters involved. A model for a safeguard proposal is provided
Manifold learning by a deep Gaussian process autoencoder
No full textThe paper presents a novel manifold learning algorithm, the deep Gaussian process autoencoder (DPGA), based on deep Gaussian processes. Deep Gaussian process autoencoder algorithm has the following two main characteristics. The former is a bottleneck structure, borrowed by variational autoencoders and the latter is based on the so-called doubly stochastic variational inference for deep Gaussian processes architecture (DSVI). The main novelties of the paper consist in DGPA algorithm and the experimental protocol for evaluating it. In fact, to the best of our knowledge, deep Gaussian processes algorithms have not been applied to manifold learning, yet. Besides, an experimental protocol is introduced, the so-called manifold learning performance protocol (MLPP), to compare quantitatively the geometric preserved properties of manifold learning projections of the proposed deep Gaussian process autoencoder with the ones of state-of-the-art manifold learning algorithms. Extensive experimental tests on eleven synthetic and five real datasets show that deep Gaussian process autoencoder compares favorably with the other manifold learning competitors
A neural network-based automated methodology to identify the crack causes in masonry structures
No full textMost masonry constructions exhibit significant crack patterns caused by differential foundation settlements. While modern numerical methods effectively address forward displacement-based problems, identifying the settlement causing a specific crack pattern remains an unsolved yet crucial challenge. For the first time, this research solves this highly non-linear back-engineering problem by proposing a robust and automated methodology synergizing artificial neural networks (ANNs) and the piecewise rigid displacement (PRD) method. The PRD’s fast computational solving allows the generation of large datasets used to train specific ANNs through Levenberg–Marquardt and conjugate gradient algorithms. Using the location and widths of the main structural cracks as input, the proposed approach offers an instantaneous and accurate ANN-based identification of foundation settlements that cause the detected damage scenario. The method is first validated on semicircular arches, and after that, its potential and effectiveness are demonstrated in a real engineering scenario, represented by the Deba bridge in Spain
Crack patterns in masonry panels coupled with the soil
No full textBased on some experiences of the authors [1-3], the present contribution proposes an approach to investigate the effects of differential settlements on masonry structures by explicitly coupling the soil with the structure while still considering as composed of no-tension material. The soil behaviour is included through a boundary integral approach, which avoids mesh discretisation issues
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