182,964 research outputs found
Connected subgroups of SO(2,n) acting irreducibly on R^{2,n}
No full textWe classify all connected subgroups of SO(2, n) that act irreducibly on R^{2, n
Optimal estimates for the triple junction function and other surprising aspects of the area functional
No full textWe consider the relaxed area functional for vector valued maps and its exact value on the triple junction function u : B1(O) → R 2 , a specific function which represents the first example of map whose graph area shows nonlocal effects. This is a map taking only three different values α, β, γ ∈ R 2 in three equal circular sectors of the unit radius ball B1(O). We prove a conjecture due to G. Bellettini and M. Paolini asserting that the recovery sequence provided in [5] (and the corresponding upper bound for the relaxed area functional of the map u) is optimal. At the same time, we show by means of a counterexample that such construction is not optimal if we consider different domains than B1(O), which still contain the same discontinuity set of u in B1(O). Such domains are obtained from B1(O) erasing part of interior of the sectors where u is constant
Weak helix submanifolds of euclidean spaces
No full textIt is shown that there exist nonstrong weak 2-helix surfaces of R
80 parole (più o meno) intorno alla venustas/ 80 words “to do” with venustas
No full textL’articolo rappresenta l’introduzione e la chiave d’accesso al lemmario di 80 parole intorno all’idea di bellezza in architettura, in epoca contemporanea, curato dall’autore. Il lemmario si compone di una lista di “voci” scritte da docenti e ricercatori di diverse Università italiane e straniere, illustrate, commentate e ampliate da una serie di immagini, brani antologici, citazioni selezionate dal curatore e autore dell’articolo. Molto più che sommatoria di singole voci, il lavoro si configura come un ipertesto semantico, nel quale anche attraverso la costruzione del sistema di apparati, si cerca di costruire una rete di relazioni tra ricerche, concetti e posizioni teoriche diverse in grado di dare conto di quella condizione plurale che caratterizza il dibattito architettonico contemporaneo. Rispetto al lavoro di curatela, dunque, l’articolo introduttivo si configura come “testimonianza” delle potenzialità di una struttura di ricerca “aperta” utilizzata per costruire e arricchire il punto di vista dell’autore ricucendo insieme le 80 parole del lemmario in una sintesi unitaria
Integration of R and Scala Using rscala
No full textThe rscala software is a simple, two-way bridge between R and Scala that allows users to leverage the unique strengths of both languages in a single project. Scala classes can be instantiated from R and Scala methods can be called. Arbitrary Scala code can be executed on-the-fly from within R and callbacks to R are supported. R packages can be developed based on Scala. Conversely, rscala also enables R code to be embedded within a Scala application. The rscala package is available from the Comprehensive R Archive Network (CRAN) and has no dependencies beyond base R and the Scala standard library
Limit of dynamic processes in delamination as the viscosity and inertia vanish
No full textWe introduce a model of dynamic evolution of a delaminated visco-elastic body with viscous adhesive. We prove the existence of solutions of the corresponding system of PDEs and then study the behavior of such solutions when the data of the problem vary slowly. We prove that a rescaled version of the dynamic evolutions converge to a "local" quasistatic evolution, which is an evolution satisfying an energy inequality and a momentum balance at all times. In the one-dimensional case we give a more detailed description of the limit evolution and we show that it behaves in a very similar way to the limit of the solutions of the dynamic model in [T. Roubicek, SIAM J. Math. Anal. 45 (2013) 101-126], where no viscosity in the adhesive is taken into account
A weak formulation for a rate-independent delamination evolution with inertial and viscosity effects subjected to unilateral constraint
No full textWe consider a system of two viscoelastic bodies attached on one side by an adhesive where a delamination process occurs. We study the dynamic of the system for small strains, subjected to external forces, suitable boundary conditions, and an unilateral constraint on the jump of the displacement at the interface between the bodies. The constraint arises in a graph inclusion, while the delamination coefficient evolves in a rate-independent way. We prove the existence of a weak solution to the corresponding system of PDEs
Atlante idrogeologico della Sardegna (scala 1:100.000)
No full textTipi e gradi di permeabilità delle principali formazioni litologiche della Sardegna riportati su carte alla scala 1:100.000 (27 tavole); ubicazione e caratteristiche idrogeologiche di pozzi, perforazioni e sorgenti considerati nello studio; curve piezometriche in formazioni alluvionali e non alluvionali. Lavoro eseguito nell'ambito del progetto speciale n° 25 della Cassa per il Mezzogiorno "Ricerche idriche sotterranee in Sardegna"
A variational approach to single crystals with dislocations
No full textWe study the graphs of maps u : Omega -> R-3 whose curl is an integral 1-current with coefficients in Z(3). We characterize the graph boundary of such maps under a suitable summability property. We apply these results to study a three-dimensional single crystal with dislocations forming general one-dimensional clusters in the framework of finite elasticity. By virtue of a variational approach, a free energy depending on the deformation field and its gradient is considered. The problem we address is the joint minimization of the free energy with respect to the deformation field and the dislocation lines. We apply closedness results for graphs of torus-valued maps, seen as integral currents and, from the characterization of their graph boundaries, we are able to prove existence of minimizers
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