103,015 research outputs found
A phenomenological model to describe turbulent friction in permeable-wall flows
No full textDescribing the canonical properties of turbulent flows over rough-permeable walls such as gravel beds, vegetatedor snow-covered surfaces have, to date, resisted complete theoretical treatment. The major complication in describing such geophysical flows is that the friction factor - Reynolds number relationships significantly deviate from their conventional Nikuradse curves or Moody diagrams derived over impermeable rough boundaries. A novel phenomenological model that describes such anomalous behavior is proposed. It expands the approach in Gioia and Chakraborty (2006) developed for rough-impermeable pipes to include finite velocity effects within the porous wall and canonical length scales governing the momentum exchanges between interstitial and superficial flows. Citation: Manes, C., L. Ridolfi, and G. Katul (2012), A phenomenological model to describe turbulent friction in permeable-wall flow
Space systems conceptual design: Analysis methods for engineering-team support
No full textThe research can be placed in the framework of designing methods for complex systems focused on the conceptual design phase of the systems’ life-cycle. More specifically, the methods presented in the dissertation belong to the category of Operational Research methods. They aim at the creation of design and analysis tools in support of the engineering team during conceptual design activities. Even though the proposed methods are referred to space-systems applications throughout the dissertation, they are easily extendable also to other engineering applications. This aspect makes the research of great theoretical and practical interest also outside the aerospace industry. A powerful methodology was developed that is typical of more specialist applications (for more detailed design phases) and that is flexible and fast to execute at the same time as required for a conceptual design phase of a complex system.Space Engineering - Astrodynamics and Space MissionsAerospace Engineerin
Massive vectors and loop observables: the g − 2 case
No full textWe discuss the use of massive vectors for the interpretation of some recent experimental anomalies, with special attention to the muon g−2. We restrict our discussion to the case where the massive vector is embedded into a spontaneously broken gauge symmetry, so that the predictions are not affected by the choice of an arbitrary energy cut-off. Extended gauge symmetries, however, typically impose strong constraints on the mass of the new vector boson and for the muon g − 2 they basically rule out, barring the case of abelian gauge extensions, the explanation of the discrepancy in terms of a single vector extension of the standard model. We finally comment on the use of massive vectors for B-meson decay and di-photon anomalies
La "giovane" Italia fuori dall'Europa. I trattati internazionali di commercio della Destra storica
No full textTutta la memoria del grande Ridolfi
No full textRecensione a: G. Cantele - R. Sbiroli, Roberto Ridolfi Bibliografia, Firenze, Olschki, 201
Ordinamento e organizzazione amministrativa dello Stato e degli enti pubblici nazionali (art. 117.2.G)
No full textIl contributo analizza come la giurisprudenza costituzionale abbia richiamato la competenza legislativa esclusiva statale prevista dall'art. 117, comma 2, lett. g, ai fini della risoluzione dei conflitti di competenza legislativa tra Stato e Regioni
Orthogonal-Array based Design Methodology for Complex, Coupled Space Systems
No full textThe process of designing a complex system, formed by many elements and sub-elements interacting between each other, is usually completed at a system level and in the preliminary phases in two major steps: design-space exploration and optimization. In a classical approach, especially in a company environment, the two steps are usually performed together, by experts of the field inferring on major phenomena, making assumptions and doing some trial-and-error runs on the available mathematical models. To support designers and decision makers during the design phases of this kind of complex systems, and to enable early discovery of emergent behaviours arising from interactions between the various elements being designed, the authors implemented a parametric methodology for the design-space exploration and optimization. The parametric technique is based on the utilization of a particular type of matrix design of experiments, the orthogonal arrays. Through successive design iterations with orthogonal arrays, the optimal solution is reached with a reduced effort if compared to more computationally-intense techniques, providing sensitivity and robustness information. The paper describes the design methodology in detail providing an application example that is the design of a human mission to support a lunar base
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