1435 research outputs found
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A Fast Implicit QR Eigenvalue Algorithm for Companion Matrices
No full textSUMMARY An implicit version of the shifted QR eigenvalue algorithm given in [D.~A.~Bini, Y.~Eidelman, I.~Gohberg, L.~Gemignani, SIAM J. Matrix Anal. Appl. 29 (2007), no. 2, 566--585] is presented for computing the eigenvalues of an companion matrix using flops and memory storage. Numerical experiments and comparisons confirm the effectiveness and the stability of the proposed method
Internal structure and linear viscoelastic properties of EVA/asphalt nanocomposites
No full textThe effect of the addition of two different organoclays as a third component in polymer modified asphalts has been investigated. Ternary mixtures were prepared by adding clay and poly(ethylene-co-vinylacetate) to the asphalt, either separately, or in the form of a premixed master batch. The performed characterizations allowed the determination of how the two methods of mixing influence the interactions between asphalt and polymer and therefore the final rheological properties. In particular, it was shown that the clay had a compatibilizing effect on asphalt and polymer and that a high compatibility between clay and polymer led to a better dispersion of the polymer in the asphalt, thus influencing the final rheological properties of the studied systems
Integrated library services within the web 2.0 context: from the development of tools for e-learning to open access repositories
No full textNella relazione verranno presentate le principali innovazioni introdotte dalle tecnologie e dagli strumenti del web 2.0 nei servizi bibliotecari. Saranno inoltre presi in considerazione alcuni repository italiani di risorse didattiche ed educative che verranno confrontati con altre esperienze europee ed internazionali. Concluderemo ipotizzando soluzioni operative sia a medio che lungo termine in ambito nazionale, per una più efficace standardizzazione e diffusione di learning object e di contenuti destinati ad archivi digitali. The present paper is directed to show, on one hand, the contribution given by Information and Communication Technologies (ICT) to teaching and learning activities that currently take place in various contexts; on the other hand it refers to other ongoing projects about the ways to archive and share educational resources. Our attention will focus on: •the importance of networking technologies for learning and for the management and dissemination of information and knowledge •the creation of innovative learning tools •the importance that is going to be taken by non-formal educational settings (such as libraries) in lifelong learning society •towards which direction it’s important to work to ensure that information sources are actually available to every active citizen
La trasmissione della memoria da Guccini ad Avatar: un ritorno al futuro
No full textRIASSUNTO Contributo nell'ambito della Storia Digitale e delle nuove tecnologie per ricordare il passato e preservare la memoria del presente. Si tratta di un ragionamento sull'evoluzione dei modi di apprendimento del passato partendo dalla rottura della trasmissione orale tra generazioni (il vecchio e il bambino di Guccini come spunto di partenza) all'esperienza del marine protagonista di Avatar, che “apprende” la memoria di un popolo in maniera immersiva virtuale. Il passaggio è segnato dagli strumenti che attualmente sono considerati all'avanguardia nel processo di apprendimento del passato e che implicano un uso consapevole delle nuove tecnologie, dal videopodcasting agli ambienti virtuali multiutente come Second Life. Una proiezione nel futuro di quanto sta avvenendo farebbe ipotizzare un ritorno a un sistema di ricezione della memoria per alcuni aspetti simile a quello usato al tempo dei nonni e bisnonni. Un ritorno al futuro. SUMMARY Lecture on the Digital History and teh new technologies helping to remember the past and preserve the memory. The lecture is about the evolution of learning methodology starting from the failure of oral transmission between generations (the old man and the child in a Guccini's song) to the experience of the marine character in Avatar movie, who "learns" the memory of a people in an immersive virtual environment. The transition is marked by tools now considered at the forefront of learning techinques and involves a conscious use of new technologies: from videopodcasting to GIS, from video to multiuser virtual environments as Second Life. An hypothetical projection of what is happening would suggest a return to a learning system similar to that was used in the time of our grandparents and great grandparents. Back to the future
LA VIA FERREA DEL TABACO EN COLOMBIA La estación de Ambalema: una experiencia académica dirigida a proyectar un "plan de restauración"
Get PDFRIASSUNTO La stazione ferroviaria di Ambalema (città dichiarata "Monumento sotrico nazionale) funzionò fino al 1985 come punto di arrivo e di partenza del tabacco che veniva traportato in Europa. Ciò che qui si descriverà è un lavoro di ricerca e didattico che si è sviluppato nel corso di “Restauración de la arquitectura”, svolto presso l'Universidad de Ibagué nell'agosto 2009. SUMMARY Until the 1985, the railway station in Ambalema (a Columbian town declared "National Historical Monument”) has been the arrival and the departure gate for the transport of the tobacco from Columbia to Europe. What is described in this contribution is the result of the teaching and research activity developed during the course of "Architectural Restoration" held to the University of Ibagué (Colombia) in August 2009
New Results on Non-Abelian Vortices - further insights into monopole, vortex and confinement
No full textWe discuss some of the latest results concerning the non-Abelian vortices.
The first concerns the construction of non-Abelian BPS vortices based on
general gauge groups of the form G= G' x U(1). In particular detailed results
about the vortex moduli space have been obtained for G'=SO(N) or USp(2N). The
second result is about the "fractional vortices", i.e., vortices of the minimum
winding but having substructures in the tension (or flux) density in the
transverse plane. Thirdly, we discuss briefly the monopole-vortex complex
The phase diagram of QCD with four degenerate quarks
No full textWe revisit the determination of the pseudo-critical line of QCD with four
degenerate quarks at non-zero temperature and baryon density by the method of
analytic continuation. We determine the pseudo-critical couplings at imaginary
chemical potentials by high-statistics Monte Carlo simulations and reveal
deviations from the simple quadratic dependence on the chemical potential
visible in earlier works on the same subject. Finally, we discuss the
implications of our findings for the shape of the pseudo-critical line at real
chemical potential, comparing different possible extrapolations
Time-resolved measurement of Landau--Zener tunneling in different bases
No full textA comprehensive study of the tunneling dynamics of a Bose--Einstein
condensate in a tilted periodic potential is presented. We report numerical and
experimental results on time-resolved measurements of the Landau--Zener
tunneling of ultracold atoms introduced by the tilt, which experimentally is
realized by accelerating the lattice. The use of different protocols enables us
to access the tunneling probability, numerically as well as experimentally, in
two different bases, namely, the adiabatic basis and the diabatic basis. The
adiabatic basis corresponds to the eigenstates of the lattice, and the diabatic
one to the free-particle momentum eigenstates. Our numerical and experimental
results are compared with existing two-state Landau--Zener models
Optimal Shape for Elliptic Problems with Random Perturbations
No full textSUMMARY In this paper we analyze the relaxed form of a shape optimization problem
with state equation The new fact is that the
term is only known up to a random perturbation . The goal is
to find an optimal coefficient , fulfilling the usual constraints
and , which minimizes a
cost function of the form Some numerical examples are shown in the last section, to
stress the difference with respect to the case with no perturbation
The three-dimensional, three state Potts model in a negative external field
No full textWe investigate the critical behaviour of the three-dimensional, three state
Potts model in presence of a negative external field h, i.e. disfavouring one
of the three states. A genuine phase transition is present for all values of
|h|, corresponding to the spontaneous breaking of a residual Z_2 symmetry. The
transition is first/second order respectively for small/large values of |h|,
with a tricritical field h_tric separating the two regimes. We provide, using
different and consistent approaches, a precise determination of h_tric; we also
compare with previous studies and discuss the relevance of our investigation to
analogous studies of the QCD phase diagram in presence of an imaginary chemical
potential