Search results for " costruzioni"
showing 10 items of 1626 documents
Computational Analysis of the Active Control of Incompressible Airfoil Flutter Vibration Using a Piezoelectric V-Stack Actuator
2021
The flutter phenomenon is a potentially destructive aeroelastic vibration studied for the design of aircraft structures as it limits the flight envelope of the aircraft. The aim of this work is to propose a heuristic design of a piezoelectric actuator-based controller for flutter vibration suppression in order to extend the allowable speed range of the structure. Based on the numerical model of a three degrees of freedom (3DOF) airfoil and taking into account the FEM model of a V-stack piezoelectric actuator, a filtered PID controller is tuned using the population decline swarm optimizer PDSO algorithm, and gain scheduling (GS) of the controller parameters is used to make the control adapti…
TECNICHE OTTICHE PER IL MONITORAGGIO DEI CORSI D’ACQUA: UNA PROCEDURA AUTOMATICA PER L’INDIVIDUAZIONE DELLA MIGLORE SEQUENZA VIDEO DA PROCESSARE CON …
Misurare con accuratezza le portate di un corso d’acqua è uno dei principali obiettivi dell’idrometria tecnica (Eltner et al., 2020) e rappresenta da decenni una vera e propria sfida per la comunità scientifica. Le osservazioni di deflusso nei corsi d’acqua sono di fondamentale importanza per qualsiasi applicazione idrologica e idraulica (Pizarro et al., 2020) e consentono di comprendere al meglio le dinamiche di processi complessi, come ad esempio le piene lampo (Perks et al., 2016). La portata è una grandezza fisica la cui stima è caratterizzata da considerevole incertezza. Gli approcci tradizionali prevedono una stima indiretta della grandezza, attraverso un metodo velocità-area, che con…
Analisi statistica della velocità del vento nel Canale di Sicilia
La Cupola del Teatro Massimo: Il contemporaneo nel 1876
2011
Hierarchical-ACA DBEM for Anisotropic Three-Dimensional Time-Harmonic Fracture Mechanics
2012
A hierarchical BEM solver for the analysis of three-dimensional anisotropic time-harmonic fracture mechanics problems is presented. A thorough investigation on the relations and interactions between the numerically computed anisotropic fundamental solutions and the algorithm used to approximate the blocks of the hierarchical matrix, namely Adaptive Cross Approximation, is carried out leading to the employed computational strategy. The use of the hierarchical matrices and iterative solvers is proved as an effective technique for speeding up the solution procedure and reducing the required memory storage in time-harmonic three-dimensional anisotropic fracture mechanics problems.
Exploiting historical rainfall and landslide data in a spatial database for the derivation of critical rainfall thresholds
2017
Critical rainfall thresholds for landslides are powerful tools for preventing landslide hazard. The thresholds are commonly estimated empirically starting from rainfall events that triggered landslides in the past. The creation of the appropriate rainfall–landslide database is one of the main efforts in this approach. In fact, an accurate agreement between the landslide and rainfall information, in terms of location and timing, is essential in order to correctly estimate the rainfall–landslide relationships. A further issue is taking into account the average moisture conditions prior the triggering event, which reasonably may be crucial in determining the sufficient amount of precipitation.…
Antropizzazione costiera e posizione della linea di riva: la spiaggia di san leone (Agrigento)
2016
In questo lavoro viene descritto un metodo di studio applicato al monitoraggio di una spiaggia dalle particolari caratteristiche dinamiche, causate proprio dal crescente sviluppo antropico avuto negli ultimi 50 anni. Il caso studio è la spiaggia di San Leone (37°15′41″N 13°35′20″E) appartenente all’Unità Fisiografica n.10 e localizzata a sud della città di Agrigento, tra le foce del fiume Akragas a NW e la foce del fiume Naro a SE (Fig. 1). Dagli anni '70 ad oggi, la spiaggia è stata oggetto di molti cambiamenti che hanno prodotto disequilibri nelle dinamiche litoranee che si sono evidenziate nel tempo attraverso avanzamenti e/o arretramenti della linea e aree ad alta criticità da erosione.…
Identification of stiffness,dissipation and input parameters of randomly excited non-linear systems: Capability of restricted potential models (RPM)
2006
Abstract A dynamic identification technique in the time domain for time invariant systems under random external forces is presented. This technique is based on the use of the class of restricted potential models (RPM), which are characterized by a non-linear stiffness and a special form of damping, that is a product of the input power spectral density (PSD) matrix and the velocity gradient of a non-linear function of the total mechanical energy. By applying It o ^ stochastic differential calculus and by specific analytical manipulations, some algebraic equations, depending on the response statistics and on the mechanic parameters that characterize RPM, are obtained. These equations can be u…
Domain decomposition in the symmetric boundary element analysis
2002
Recent developments in the symmetric boundary element method (SBEM) have shown a clear superiority of this formulation over the collocation method. Its competitiveness has been tested in comparison to the finite element method (FEM) and is manifested in several engineering problems in which internal boundaries are present, i.e. those in which the body shows a jump in the physical characteristics of the material and in which an appropriate study of the response must be used. When we work in the ambit of the SBE formulation, the body is subdivided into macroelements characterized by some relations which link the interface boundary unknowns to the external actions. These relations, valid for e…
Fractional-order poromechanics for a fully saturated biological tissue: Biomechanics of meniscus
2023
Biomechanics of biological fibrous tissues as the meniscus are strongly influenced by past histories of strains involving the so-called material hereditariness. In this paper, a three-axial model of linear hereditariness that makes use of fractional-order calculus is used to describe the constitutive behavior of the tissue. Fluid flow across meniscus' pores is modeled in this paper with Darcy relation yielding a novel model of fractional-order poromechanics, describing the evolution of the diffusion phenomenon in the meniscus. A numerical application involving an 1D confined compression test is reported to show the effect of the material hereditariness on the pressure drop evolution.