1,721,541 research outputs found
Expanded polystyrene (EPS) in road construction: Twenty years of Italian experiences
Full text linkExpanded polystyrene (EPS) is a thermoplastic material, derived from pre-expanded polystyrene beads, that combines an extreme lightweight with versatile strength and thermal insulation. These characteristics made EPS an excellent alternative to natural materials for the feasibility of building and construction projects that would otherwise destined, for time and implementation costs, to be postponed or alienated. Specifically, this technology has been successfully used in road infrastructure sector in the last twenty years in the construction of roads, bridge abutments, lightweight embankments and backfills, above all for the rapid restoration of compromised roads following landslide or calamitous events, representing an interesting and resilient solution in areas exposed to seismic risk or persistent vibratory actions. Thus, the authors want to offer a critical analysis of different EPS road applications in Italy, considering benefits and drawbacks, proposing technical and economic considerations for ideal conditions of use and suggesting failure analysis methods and tools. © 2020 The Author(s)
Quasi-periodic solutions for quasi-linear generalized KdV equations
No full textWe prove the existence of Cantor families of small amplitude, linearly stable, quasi-periodic solutions of quasi-linear autonomous Hamiltonian generalized KdV equations. We consider the most general quasi-linear quadratic nonlinearity. The proof is based on an iterative Nash–Moser algorithm. To initialize this scheme, we need to perform a bifurcation analysis taking into account the strongly perturbative effects of the nonlinearity near the origin. In particular, we implement a weak version of the Birkhoff normal form method. The inversion of the linearized operators at each step of the iteration is achieved by pseudo-differential techniques, linear Birkhoff normal form algorithms and a linear KAM reducibility scheme
Transfers of energy through fast diffusion channels in some resonant PDEs on the circle
Full text linkIn this paper we consider two classes of resonant Hamiltonian PDEs on the circle with non-convex (respect to actions) first order resonant Hamiltonian. We show that, for appropriate choices of the nonlinearities we can find time-independent linear potentials that enable the construction of solutions that undergo a prescribed growth in the Sobolev norms. The solutions that we provide follow closely the orbits of a nonlinear resonant model, which is a good approximation of the full equation. The non-convexity of the resonant Hamiltonian allows the existence of fast diffusion channels along which the orbits of the resonant model experience a large drift in the actions in the optimal time. This phenomenon induces a transfer of energy among the Fourier modes of the solutions, which in turn is responsible for the growth of higher order Sobolev norms.Peer ReviewedPostprint (published version
Quasi-Periodic Traveling Waves on an Infinitely Deep Perfect Fluid Under Gravity
No full textWe consider the gravity water waves system with a periodic one-dimensional interface in infinite depth and we establish the existence and the linear stability of small amplitude, quasi-periodic in time, traveling waves. This provides the first existence result of quasi-periodic water waves solutions bifurcating from a completely resonant elliptic fixed point. The proof is based on a Nash-Moser scheme, Birkhoff normal form methods and pseudo differential calculus techniques. We deal with the combined problems of small divisors and the fully-nonlinear nature of the equations. The lack of parameters, like the capillarity or the depth of the ocean, demands a refined nonlinear bifurcation analysis involving several nontrivial resonant wave interactions, as the well-known "Benjamin-Feir resonances". We develop a novel normal form approach to deal with that. Moreover, by making full use of the Hamiltonian structure, we are able to provide the existence of a wide class of solutions which are free from restrictions of parity in the time and space variables
Influence of chemical additives and wax modifiers on odor emissions of road asphalt
No full textThe use of a broad range of asphalt additives is a well-established practice in road pavement engineering for the production of high-performance hot-mix and warm-mix asphalt mixtures. The study aimed to verify and to assess, though an analytical-sensory approach based on artificial olfactory system (AOS), the effects of five different asphalt additives (chemical additives, odor suppressant agent and wax modifiers) on the odorous patterns of asphalt emissions at typical mixing and laying temperatures. The AOS has made possible to identify a specific odor fingerprint of each additive. However, once added to asphalt, these agents did not establish with binder effects of synergy, additivity or antagonism, but appear to be as neutral elements by an odorous point of view. The odorous patterns of emissions generated by heating neat asphalt at various temperatures in laboratory scale tend to coincide with those of asphalt/additive mixtures, underlining how the bituminous binder odor resulted to be hiding or masking compared to that of only-additives. © 2018 Elsevier Lt
Sacerdozi municipali nella regio VIII (Aemilia).
No full textIndagine su alcuni sacerdozi municipali documentati nella regio VIII (Aemilia): per ogni sacerdote vengono analizzati origo, carriera e rango sociale. Per quanto riguarda il flaminato ed il flaminicato del culto imperiale si ha abbondanza di testimonianze, in particolare ad Ariminum e a Mutina; mentre il flaminato riservato alla venerazione di una divinità è attestato solo a Mutina, da cui proviene un’epigrafe che ricorda un flamen Dialis. Di notevole interesse è la presenza di haruspices, sacerdoti documentati piuttosto raramente e soprattutto in Etruria: su un’iscrizione di Faventia di I secolo d.C. sono menzionati due aruspici, padre e figlio
Sobolev norms explosion for the cubic NLS on irrational tori
Full text linkWe consider the cubic nonlinear Schrödinger equation on 2-dimensional irrational tori. We construct solutions which undergo growth of Sobolev norms. More concretely, for every s>0, s≠1 and almost every choice of spatial periods we construct solutions whose H^s Sobolev norms grow by any prescribed factor. Moreover, for a set of spatial periods with positive Hausdorff dimension we construct solutions whose Sobolev norms go from arbitrarily small to arbitrarily large. We also provide estimates for the time needed to undergo the norm explosion. Note that the irrationality of the space periods decouples the linear resonant interactions into products of 1-dimensional resonances, reducing considerably the complexity of the resonant dynamics usually used to construct transfer of energy solutions. However, one can provide these growth of Sobolev norms solutions by using quasi-resonances relying on Diophantine approximation properties of the space periods
Caratterizzazione prestazionale della segnaletica stradale orizzontale
No full textPer il conducente il ruolo della segnaletica orizzontale nel controllo del tracciato stradale e nel governo del
veicolo è indiscutibilmente riconosciuto. Ad essa non è attribuito solo il compito di delimitare gli spazi della
piattaforma stradale ma è richiesta l’essenziale funzione di guida ottica, di forte richiamo all’attenzione del
guidatore attraverso un opportuno contrasto di colore e luminanza con la superficie stradale, affinché lo
stesso riceva indicazioni per particolari comportamenti da seguire.
La segnaletica orizzontale da utilizzare come guida ottica del tracciato stradale in ambienti urbani di
circolazione può impiegare materiali con molteplici formulazioni e tipologie applicative, per soddisfare a
precise richieste comportamentali e prestazionali riguardo alla posizione in piattaforma e alla coesistenza
delle diverse categorie di traffico.
Anche l’ambito propriamente urbano di circolazione, diversamente da quanto si possa desumere per la
minore velocità di progetto rispetto a sezioni gerarchicamente superiori (autostrade e strade urbane ed
extraurbane principali), richiede alla segnaletica orizzontale una funzione di nitido riconoscimento degli spazi
in carreggiata favorendo la canalizzazione ordinata dei flussi veicolari ed assegnando corridoi e regole
esplicite agli Utenti più deboli della strada.
Ancora più decisivo è l’apporto della segnaletica stradale orizzontale nella marcia notturna, nella guida in
condizioni meteorologiche avverse, in quadri prospettici complessi e densi d’informazioni ai margini della
carreggiata che rendono al conducente più faticoso il compito di procedere in modo ordinato negli spazi ad
egli assegnati.
La moderna gestione dei servizi segnaletici urbani richiede una segnaletica orizzontale sempre più
specializzata e performante, che possieda gli indispensabili requisiti di efficienza e durabilità. I materiali
impiegati per la segnaletica orizzontale sono oggetto di una recente evoluzione normativa che ha tenuto
espressamente conto di tali requisiti nella definizione di specifiche tecniche di carattere essenzialmente
prestazionale. Efficienza e durabilità scaturiscono dalla qualità del prodotto segnaletico ma non possono
prescindere dalla massima attenzione che deve essere dedicata alle fasi di messa in opera ed allo stato
della pavimentazione stradale su cui il segnale stesso viene applicato, dipendente da tessitura, età, umidità,
segnaletica preesistente, irregolarità e fessurazioni. Le fasi cosiddette preparatorie, di pulizia, fissaggio e le
modalità di prima apertura al traffico delineano irrimediabilmente la durata della vita utile funzionale della
segnaletica orizzontale, più di quanto sia lecito temere dalle azioni aggressive esercitate dagli agenti
atmosferici e dal traffico veicolare
Long Time Dynamics of Quasi-linear Hamiltonian Klein–Gordon Equations on the Circle
No full textWe consider a class of Hamiltonian Klein-Gordon equations with a quasilinear, quadratic nonlinearity under periodic boundary conditions. For a large set of masses, we provide a precise description of the dynamics for an open set of small initial data of size epsilon showing that the corresponding solutions remain close to oscillatory motions over a time scale epsilon (-9/4 + delta )for any delta > 0 . The key ingredients of the proof are normal form methods, para-differential calculus and a modified energy approach
Daytime and nighttime color appearance of pigmented asphalt surface treatments
No full textThe use of distinctive and decorative road colored pavements intended for motorized traffic, cyclists and pedestrians have dramatically increased worldwide. They could take the form of overlay, when the colored material is placed on top of the pavement, or embedded, when the colored material is mixed directly into the pavement, exploiting the natural chromatic properties of stone aggregates or powder pigments. Colored pavements are not generally considered as signs or road markings and therefore, no having a legal status, are not subjected to chromaticity requirements. Thus, the paper proposed a rational methodology for the chromatic characterization of colored asphalt pavements, considering different thin cold pigmented high friction road surface treatments, i.e. pigmented slurry seals (red, green and blue), prepared with a clear synthetic emulsion. The experimental procedure had the ambition to predict the chromatic aspect of these pavements, based on direct instrumental measurements of chromaticity coordinates on laboratory scale samples, for several pigment contents in daytime and nighttime. Experimental results testified how the correct transfer and application of a particular color to a road pavement, which often perform traffic functions, cannot be separated from an integrated design between pavement materials selection and road lighting project. © 2019 Elsevier Lt
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