668 research outputs found
Recensione di F. Suard, Guide de la chanson de geste et de sa postérité littéraire (XIe-XVe siècle) (2011
No full textFully anisotropic unstructured grid generation with application to aircraft design
No full textThis paper describes a fully automatic 3D anisotropic mesh generation method for domains of arbitrary shape. The spacing of the boundary mesh is computed by the analysis of the principal curvatures and directions of the boundary surfaces. The spacing in the domain is obtained by interpolation of the spacing at the boundaries on a suitably constructed background mesh. Examples which illustrate the performance of the proposed methodology are presented
Andamento climatico e incidenza delle malattie fitosanitarie della vite in Trentino
No full textThe temperature has risen in recent decades: from observations since 1989 the average temperature has increased by almost
1.5°C. This has caused an increase in vine growing beyond 800-850 m.a.s.l. and an advance of phenology. there has been an
increase in the average annual rainfall with a reduction in the number of rainy events, but an increase in their intensity.
Most rain, higher spring temperatures and milder winters have led to premature ripening of oospores of downy mildew, with
higher incidence of primary infections and defence anticipation of more than 10 days.
Also other fungal diseases have adapted to the climate: powdery mildew causes a great impact in the management of
defense, even in flat areas.
The temperature increase has allowed the proliferation of new species of insects, while known insects, have adapted the
cycle.
Also mealybugs have increased their presence, in addition to the spread of new species as Planococcus ficus which,
originally from Mediterranean area, nowadays can be found on almost the whole province. This results in more
phytosanitary problems, and maturation of the grapes with formation of aromatic compounds in wine not entirely typical of
the area
HIGH-ORDER DISCONTINUOUS GALERKIN SOLUTION OF UNSTEADY PROBLEMS USING MODIFIED EXTENDED BACKWARD DIFFERENTIATION FORMULAE
No full textThis paper presents the results of a high-order Discontinuous Galerkin (DG)
method coupled with Modified Extended Backward Differentiation Formulae (MEBDF) for
time-dependent compressible flows. The primary objective of this work is to assess the per-
formance of the scheme for a well known inviscid test case as well as to show the potential of
this approach in the simulation of a complex turbulent flow through a turbine cascade. The first
test case considered is the inviscid isentropic vortex convected on a cartesian grid, for which
an exact solution is available. The analysis is performed for three successively refined grids
and progressively finer time steps, by using schemes of equal space and time accuracy ranging
from 2nd to 4th order. The second test case is the subsonic flow through a turbine cascade which
features an unsteady vortex shedding behind the trailing edge of turbine blades. The analysis
is performed for a fixed spatial approximation and a fixed time step by considering MEBDF
schemes up to 4th order of accuracy
Neck modularity in total hip arthroplasty: a retrospective study of nine hundred twenty-eight titanium neck implants with a maximum follow-up of eighteen years
No full textPurpose: Neck modularity was introduced to improve total hip arthroplasty (THA) accuracy, but it has been associated with early breakages and corrosion issues. In our hospital, modular necks have been in clinical use since the 1990s. We retrospectively analysed the occurrence of these sequelae in implants placed between January 2000 and December 2014. Methods: Survival data from patients operated on in our hospital were obtained from the regional arthroplasty registry (Registro dell’Impiantologia Protesica Ortopedica, RIPO). The cohort comprised 928 THAs on 908 patients. The average patient age was 67.8 years. Main indications were primary osteoarthritis (71.4%), fracture (9.2%), congenital dysplasia or congenital luxation (7.8%), and idiopathic osteonecrosis (6.4%). All femoral stems were cementless, with 318 anatomically shaped (34.3%), 579 straight (62.4%), and 31 short stems (3.3%). All necks used were made of titanium alloy. The average follow-up time was 9.6 years (range, 4–18 years). Results: In total, 66 revisions were reported. The main revision causes were periprosthetic fractures (33.3%), aseptic stem loosening (19.7%), luxation (18.2%), and implant breakage (12.1%). Five modular neck breakages were recorded. The overall survival rate was 87.7% at 17 years. We did not observe any component corrosion. The neck breakage rate was 0.5%, and the luxation rate was 1.3%. Conclusions: Our experience suggests that neck modularity is a safe, effective way to reconstruct the proximal femur in THA patients. We attribute the absence of corrosion to the exclusive use of titanium necks
On the development of an implicit high-order Discontinuous Galerkin method for DNS and implicit LES of turbulent flows
No full textIn recent years Discontinuous Galerkin (DG) methods have emerged as one of the most promising high-order discretization techniques for CFD. DG methods have been successfully applied to the simulation of turbulent flows by solving the Reynolds averaged Navier–Stokes (RANS) equations with first-moment closures. More recently, due to their favorable dispersion and dissipation properties, DG discretizations have also been found very well suited for the Direct Numerical Simulation (DNS) and Implicit Large Eddy Simulation (ILES) of turbulent flows.
The growing interest in the implementation of DG methods for DNS and ILES is motivated by their attractive features. In particular, these methods can easily achieve high-order accuracy on arbitrarily shaped elements and are perfectly suited to hp-adaptation techniques. Moreover, their compact stencil is independent of the degree of polynomial approximation and is thus well suited for implicit time discretization and for massively parallel implementations.
In this paper we focus on recent developments and applications of an implicit high-order DG method for the DNS and ILES of both compressible and incompressible flows. High-order spatial and temporal accuracy has been achieved using the same numerical technology in both cases. Numerical inviscid flux formulations are based on the exact solution of Riemann problems (suitably perturbed in the incompressible case), and viscous flux discretizations rely on the BR2 scheme. Several types of high-order (up to order six) implicit schemes, suited also for DAEs, can be employed for accurate time integration. In particular, linearly implicit Rosenbrock-type Runge–Kutta schemes have been used for all the simulations presented in this work. The massively separated incompressible flow past a sphere at ReD=1000, with transition to turbulence in the wake region, is considered as a DNS test case, while the potential of the ILES is demonstrated by computing the compressible transitional flow at Rec=60 000, M∞=0.1and α=8°, around the Selig–Donovan 7003 airfoil. The computed solutions are compared with experimental data and numerical results available in the literature, showing good agreement
Optimal Runge-Kutta smoothers for the p-multigrid discontinuous Galerkin solution of the 1D Euler equations
No full textA proposito di Marrou, Agostino e la musica
No full textDal Traité de la musique selon l'esprit de Saint Augustin (1942) di H.-I. Marrou emerge la relazione tra la musica francese degli anni Trenta e il pensiero non-conformista. L’accento posto sul momento fruitivo della musica e in particolare sul suo fine etico si riallaccia ai propositi della rivoluzione spirituale che informa il cosiddetto spirito del 1930 e il manifesto della Jeune France: leggere il Traité può essere utile per affrontare le poetiche musicali umaniste degli anni Trenta, e al contempo il contesto storico spiega e giustifica il pensiero di Marrou, che può apparire altrimenti poco interessante.
Quest'ultimo viene infatti sviluppato sulla scia del platonismo cristiano mediato da Agostino, che viene sottoposto a una serie di piccoli mutamenti in funzione di una migliore e più attuale teologia morale. L'esito filosofico non è tuttavia dei più convincenti, vuoi per i numerosi appelli al principio d'autorità, vuoi per le frequenti contraddizioni argomentative che emergono dal testo in modo evidente. La tensione tra la fedeltà alla dottrina, il tentativo di rilettura della musica in chiave apologetica e la proposta di una filosofia pratica producono così un vistoso scacco metodologico che rappresenta uno dei limiti maggiori del Trattato.
Le considerazioni di Marrou sul rapporto tra cristianesimo e filosofia antica sono certamente molto interessanti ma assai discutibili da un punto di vista storico-filosofico. L’autore si spinge fino a correggere Agostino stesso, soprattutto per quanto riguarda la componente pitagorica della sua riflessione, per sottolineare invece una componente religiosa della musica che non sembra così evidente nella riflessione agostiniana.
H.-I. Marrou's Traité de la musique selon l'esprit de Saint Augustin (1942) is a useful document about the relationship between 1930s French music and non-conformist culture. His stress on the moral aim of music recalls the claim for a spiritual revolution that informs the spirit of 1930 and Jeune France's manifesto: the reading of Marrou's Traité helps us defining the humanistic poetics of music of the '30s, and the historical context mutually explains and justify most of Marrou's thought (otherwise apparently weak).
His thought is in fact developed in the wake of Christian Platonism revised by Augustine, subject to a series of small changes in sight of a better and more relevant moral theology. The philosophical outcome isn't very convincing, both for many appeals to the authority principle, and for frequent contradictions clearly emerging in his arguments. The tension between the fidelity to the doctrine, the attempts to re-read the music from an apologetic viewpoint and the aim to suggest a practical philosophy produces a methodological setback so striking that it represents one of the greater limits of the Treaty.
Marrou's remarks about the relationship between Christianity and ancient philosophy are certainly as interesting as questionable from the point of view of the history of philosophy. He goes so far to correct Augustine himself, especially as regards the Pythagorean influence on his thought, to stress instead a religious component of the music that doesn't seem so evident in the Augustinian analysis
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