1,721,041 research outputs found
Pratiche strategiche di pianificazione. Riflessioni a partire da nuovi spazi urbani in costruzione
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On the coupling of hyperbolic and parabolic systems: analytical and numerical approach
No full textWe deal with the coupling of hyperbolic and parabolic systems in a one-dimentional domain Ω divided into two disjoint subdomains Ω+ and Ω-. Our main concern is to find out the proper interface conditions to be fulfilled at the surface separating the two domains. Next, we will use them in the numerical approximation of the problem. The justification of the interface conditions is based on a singular perturbation analysis, that is, the hyperbolic system is rendered parabolic by adding a small artificial "viscosity". As this goes to zero, the coupled parabolic-parabolic problem degenerates into the original one, yielding some conditions at the interface. These we take as interface conditions for the hyperbolic-parabolic problem. Actually, we discuss two alternative sets of interface conditions according to whether the regularization procedure is variational or nonvariational. We show how these conditions can be used in the frame of a numerical approximation to the given problem. Furthermore, we discuss a method of resolution which alternates the resolution of the hyperbolic problem within Ω- and of the parabolic one within Ω+. The spectral collocation method is proposed, as an example of space discretization (different methods could be used as well); both explicit and implicit time-advancing schemes are considered. The present study is a preliminary step toward the analysis of the coupling between Euler and Navier-Stokes equations for compressible flows. © 1989
La condivisione dell’Irpef tra livelli di governo: alcune questioni aperte
No full textQuesto contributo analizza alcune principali questioni poste dalla prospettiva di un rafforzamento del peso dell’imposta personale sui redditi nel finanziamento dei livelli sub-centrali di governo. Il paragrafo 1 descrive l’attuale assetto delle addizionali regionali e locali all’Irpef; il paragrafo 2 fornisce alcune informazioni sulle esperienze internazionali; il paragrafo 3 discute i principi generali della scelta tra addizionale e sovraimposta quali modalità di condivisione tra centro e periferia dell’imposta sui redditi personali; il paragrafo 4, infine, illustra alcuni possibili interventi di riforma sull’attuale sistema delle addizionali Irpef
Inequations variationnelles non coercives
No full textLet K be a convex subset of a real Hilbert space V, let a:{u,v}→a(u,v) be a real bilinear continuous form on V×V, which is positive semidefinite but not necessarily coercive, and let L be given in V′. We prove quite general existence results for the problem: Find u∈K such that a(u,u−v)≤⟨L,u−v⟩, for all v∈K
Sharing of the Personal Income Tax among Levels of Government: Some Open Issues from the Italian Experience
No full textThis paper considers some open issues concerning the role of the personal income tax in regional and local finance. It compares different technical instruments to share the personal income tax among levels of government, analyzing particularly the differential effects of the two main forms of overlapping taxation, the surtax and the surcharge. It is proved that both instruments increase the redistributional impact of personal income taxation, the surcharge to a larger extent than the surtax. The second part of the paper describes the present framework of the sharing of income tax in Italy, based upon regional and local surtaxes, and the new perspectives opened by the reform of intergovernmental fiscal relations recently approved by Parliament
SHARING THE PERSONAL INCOME TAX AMONG LEVELSOF GOVERNMENT: SOME OPEN ISSUES FROM THE ITALIANEXPERIENCE
No full textThis paper considers some open issues concerning the role of the personal income tax in regional and local finance. It compares different technical instruments to share the personal income tax among levels of government, analyzing particularly the differential effects of the two main forms of overlapping taxation, the surtax and the surcharge. It is proved that both instruments increase the redistributional impact of personal income taxation, the surcharge to a larger extent than the surtax. The second part of the paper describes the present framework of the sharing of income tax in Italy, based upon regional and local surtaxes, and the new perspectives opened by the reform of intergovernmental fiscal relations recently approved by Parliament
Adaptive domain decomposition methods for advection dominated equations
No full textWe consider several adaptive methods of domain decomposition for the solution of advection-diffusion boundary value problems. Adaptivity relies on accounting for the local direction of the convective field at subdomain interfaces. A convergence analysis is carried out both at differential and numerical level, and the algorithmical aspects of these methods are considered
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