196,310 research outputs found
M. Quaini, Per la storia del paesaggio agrario in Liguria.
No full textChevallier Raymond. M. Quaini, Per la storia del paesaggio agrario in Liguria.. In: Études rurales, n°58, 1975. pp. 116-117
Lo sguardo del geografo: Massimo Quaini, l’archeologia, la storia
No full textIl saggio discute, a partire da due punti di vista differenti, quelli di una archeologa e di uno storico, il modo in cui uno dei più importanti geografi degli ultimi decenni, Massimo Quaini, dalla fine degli anni Sessanta, abbia intrapreso un dialogo, non sempre con successo, con le discipline sorelle della geografia storica: l'archeologia e la storia sociale. Il contributo riflette sul percorso sperimentale di Quaini “verso una nuova geografia” e sui numerosi incontri, separazioni, percorsi paralleli e divergenti che si sono verificati lungo quella sua esperienza di ricerca. Una particolare attenzione è dedicata alle esperienze e le frequentazioni scientifiche e culturali di Massimo Quaini che caratterizzarono in diversi momenti la sua esperienza genovese, ed in particolare quelle del Centro Studi Ligure sui Villaggi Deserti – da cui originarono i dibattiti intorno alla geografia delle popolazioni e alla storia della cultura materiale –, e successivamente quelle legate al Seminario Permanente di Storia Locale e alla lunga discussione intorno alla microstoria e ai suoi diversi esiti. Il saggio ha dunque una specifica caratterizzazione metodologica e storiografica, e si confronta con prospettive esplicitamente interdisciplinari che riguardano, tra le altre, la storia del paesaggio e dell’ambiente, così come la storia sociale e culturale
M. Quaini, Per la storia del paesaggio agrario in Liguria.
No full textChevallier Raymond. M. Quaini, Per la storia del paesaggio agrario in Liguria.. In: Études rurales, n°58, 1975. pp. 116-117
Goffredo Casalis e le origini del "Dizionario geografico-storico-statistico-commerciale degli Stati di S. M. il Re di Sardegna"
No full text
A localized reduced-order modeling approach for PDEs with bifurcating solutions
No full textReduced-order modeling (ROM) commonly refers to the construction, based on a few solutions (referred to as snapshots) of an expensive discretized partial differential equation (PDE), and the subsequent application of low-dimensional discretizations of partial differential equations (PDEs) that can be used to more efficiently treat problems in control and optimization, uncertainty quantification, and other settings that require multiple approximate PDE solutions. Although ROMs have been successfully used in many settings, ROMs built specifically for the efficient treatment of PDEs having solutions that bifurcate as the values of input parameters change have not received much attention. In such cases, the parameter domain can be subdivided into subregions, each of which corresponds to a different branch of solutions. Popular ROM approaches such as proper orthogonal decomposition (POD), results in a global low-dimensional basis that does not respect the often large differences in the PDE solutions corresponding to different subregions. In this work, we develop and test a new ROM approach specifically aimed at bifurcation problems. In the new method, the k-means algorithm is used to cluster snapshots so that within cluster snapshots are similar to each other and are dissimilar to those in other clusters. This is followed by the construction of local POD bases, one for each cluster. The method also can detect which cluster a new parameter point belongs to, after which the local basis corresponding to that cluster is used to determine a ROM approximation. Numerical experiments show the effectiveness of the method both for problems for which bifurcation cause continuous and discontinuous changes in the solution of the PDE
Italie : la meilleure carte de la plaine de Ferrare. Una carta del Ferrarese del 1814. Giorgi G., Pezzoli S., Quaini M. et Venturi S., (1987)
No full textPéchoux Pierre-Yves. Italie : la meilleure carte de la plaine de Ferrare. Una carta del Ferrarese del 1814. Giorgi G., Pezzoli S., Quaini M. et Venturi S., (1987). In: Méditerranée, tome 70, 1-2-1990. La Méditerranée dans ses états, sous la direction de Michèle Joannon et Lucien Tirone. pp. 83-84
Reduced basis model order reduction for Navier–Stokes equations in domains with walls of varying curvature
No full textWe consider the Navier–Stokes equations in a channel with a narrowing and walls of varying curvature. By applying the empirical interpolation method to generate an affine parameter dependency, the offline-online procedure can be used to compute reduced order solutions for parameter variations. The reduced-order space is computed from the steady-state snapshot solutions by a standard POD procedure. The model is discretised with high-order spectral element ansatz functions, resulting in 4752 degrees of freedom. The proposed reduced-order model produces accurate approximations of steady-state solutions for a wide range of geometries and kinematic viscosity values. The application that motivated the present study is the onset of asymmetries (i.e. symmetry breaking bifurcation) in blood flow through a regurgitant mitral valve, depending on the Reynolds number and the valve shape. Through our computational study, we found that the critical Reynolds number for the symmetry breaking increases as the wall curvature increases
A hybrid projection/data-driven reduced order model for the Navier-Stokes equations with nonlinear filtering stabilization
No full textWe develop a Reduced Order Model (ROM) for the Navier-Stokes equations with nonlinear filtering stabilization. Our approach, that can be interpreted as a Large Eddy Simulation model, combines a three-step algorithm called Evolve-Filter-Relax (EFR) with a computationally efficient finite volume method. The main novelty of our ROM lies in the use within the EFR algorithm of a nonlinear, deconvolution-based indicator function that identifies the regions of the domain where the flow needs regularization. The ROM we propose is a hybrid projection/data-driven strategy: a classical Proper Orthogonal Decomposition Galerkin projection approach for the reconstruction of the velocity and the pressure fields and a data-driven reduction method to approximate the indicator function used by the nonlinear differential filter. This data-driven technique is based on interpolation with Radial Basis Functions. We test the performance of our ROM approach on two benchmark problems: 2D and 3D unsteady flow past a cylinder at Reynolds number 0≤Re≤100. The accuracy of the ROM is assessed against results obtained with the full order model for velocity, pressure, indicator function and time evolution of the aerodynamics coefficients
A linear filter regularization for POD-based reduced-order models of the quasi-geostrophic equations
No full textWe propose a regularization for reduced-order models (ROMs) of the quasi-geostrophic equations (QGE) to increase accuracy when the proper orthogonal decomposition (POD) modes retained to construct the reduced basis are insufficient to describe the system dynamics. Our regularization is based on the so-called BV-α model, which modifies the nonlinear term in the QGE and adds a linear differential filter for the vorticity. To show the effectiveness of the BV-α model for ROM closure, we compare the results computed by a POD-Galerkin ROM with and without regularization for the classical double-gyre wind forcing benchmark. Our numerical results show that the solution computed by the regularized ROM is more accurate, even when the retained POD modes account for a small percentage of the eigenvalue energy. Additionally, we show that, although computationally more expensive than the ROM with no regularization, the regularized ROM is still a competitive alternative to full-order simulations of the QGE
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