86 research outputs found
Progetti, equilibri e variazioni: forme del "razionalismo" in Max Bill e in Luigi Veronesi
No full textUn confronto fra due dei maggiori autori dell'astrattismo fra gli anni Trenta e Quaranta a livello europeo, in relazione al modo di porsi nei confronti dei temi della composizione e dell'invenzione. Mentre Veronesi aspira a confrontarsi con le proposte del Bauhaus, pur difendendo una dimensione di fantasia e di sperimentazione, Bill influenza i modi e i tempi del giudizio sull'astrattismo europeo in Italia. Un punto di connessione viene individuato nella riflessione sul tema della variazione di un tema o di una forma
Lucio Fontana e Alberto Giacometti: un dialogo a distanza (con qualche illustre ospite)
No full textIl confronto fra Lucio Fontana e Alberto Giacometti, nel volume costruito sulla definizione di rapporti sulla direttiva "nord-sud" si manifesta in via indiretta, in relazione al loro reciproco modo di intendere lo spazio, in chiave esistenziale o in relazione con le definizioni scientifiche. Analogie e differenze vengono riprese attraverso il rapporto con le posizioni critiche e con le motivazioni dell'uno e dell'altro, che vengono riconosciuti, nel confronto con le posizioni di autori americani contemporanei, come espressione di un'arte europea che definisce i suoi parametri sulla qualificazione simbolica dell'opera, rispetto a quella, più strutturale, del mondo nord-americano
Experimental evaluation of COMIS results for ventilation of a detached house
No full textThis paper presents a comparison of measured airflows in a detached house with the results of a simulation model. The house was built mainly for experimental purposes and therefore allows very detailed measurements of the interior and the outside microclimate (e.g., wind velocity, air temperature, humidity, etc.). The air permeability of the house was characterized by means of a pressurization technique. Ventilation measurements were carried out using the tracer gas technique (decay method with two gases, SF6 and N2O). A mobile, multizone, multitracer apparatus, designed and built by the authors, was used. The measured data were analyzed using an inverse problem technique in order to calculate the time histories of the airflow rates during the measurement period and their uncertainties. The building envelope air-leakage coefficients and meteorological data were used in COMIS to obtain the simulated airflow rates. The comparison with measured airflows allows one to define the application limits of the model discussed here
Aerodynamic shape optimization of rotary wing aircraft components using advanced multiobjective evolutionary algorithms
No full textThe aim of this Doctoral Thesis, sponsored by AgustaWestland, is the design and development of a multi-objective optimization procedure that involves the application of the GeDEA-II, a powerful and time-saving evolutionary algorithm recently developed by the author at the University of Padova, able to perform multi-objective optimization analyses with the general approach of the Pareto frontier search. When compared to other state-of-the-art multi-objective evolutionary algorithms, it features novel crossover and mutation operators, and demonstrated superior performance.
This optimizer supervises an automatic optimization loop involving the CFD commercial and free, open source solvers, respectively Fluent® and OpenFOAM®.
Altair Hyperworks package is chosen as the free-form-deformation parameterization engine.
The test cases chosen to demonstrate the strength of the procedure implemented concern the aerodynamic optimization of the AgustaWestland ERICA nose region, and the optimization of the intake 1 of the AW101 helicopter, that is really challenging problems from both the engineering and the industrial point of view.
Starting from the the geometry elaboration and proceeding to the results discussion, each step of the optimization procedure is described in details, with particular focus on the automatic optimization loop, directly programmed by the author in both UNIX/Linux and Windows environments.
The results obtained surely demonstrate the effectiveness of the multiobjective approach chosen to carry out this work.
Furthermore, some suggestions for future improvements and developments are provided, with the purpose to increase the strength of the discussed multi-objective optimization tool.Lo scopo di questa tesi di Dottorato in Energetica, finanziata da AgustaWestland, consiste nella progettazione e sviluppo di una procedura di ottimizzazione multi-obiettivo, che comprende l’applicazione del GeDEA-II, un algoritmo genetico/evolutivo recentemente sviluppato dall’autore presso l’Università di Padova.
Tale algoritmo permette di effettuare analisi di ottimizzazione multiobiettivo, sfruttando l’approccio del tutto generale che va sotto il nome di “Ricerca del Fronte di Pareto”. Rispetto ad altri algoritmi evolutivi multi-obiettivo “state-of-the-art”, esso presenta operatori di crossover e mutazione innovativi, che ne migliorano in maniera significativa le performance.
Questo ottimizzatore è accoppiato con i codici CFD commerciali e gratuiti, rispettivamente Fluent® and OpenFOAM®. Il pacchetto Altair Hyperworks, codice ufficiale presso AgustaWestland per il pre-processing di fusoliere di elicottero, è scelto quale software per la parametrizzazione free-form. I casi test scelti per dimostrare l’efficacia di tale procedura consistono nell’ottimizzazione aerodinamica della regione frontale del tilt rotor dimostrativo ERICA, e della presa d’aria 1 dell’elicottero AW101. Tali casi costituiscono problemi stimolanti sia da un punto di vista puramente ingegneristico, sia da un punto di vista industriale. A partire dall’elaborazione della geometria, e procedendo con la discussione dei risultati ottenuti, ogni passo della procedura di ottimizzazione è descritto in dettaglio, con particolare enfasi dedicata al ciclo di ottimizzazione, sviluppato dall’autore sia in ambiente UNIX, sia in ambiente Windows. I risultati ottenuti dimostrano l’efficacia dell’approccio di ottimizzazione basato sull’algoritmo GeDEAII, scelto per sviluppare questo lavoro. Inoltre, vengono forniti alcuni consigli inerenti lo sviluppo futuro di questa procedura di ottimizzazione, con l’obiettivo di migliorare ulteriormente le capacità e la robustezza del ciclo di ottimizzazione
Towards streamlined restoration of macroalgal forests: integrating suspended algaculture and ex situ outplanting
No full textEricaria amentacea, a key habitat-forming brown macroalga on Mediterranean rocky coasts, faces severe decline
due to anthropogenic stressors and climate change. Natural recovery is hindered by its limited dispersal and
connectivity potential, and active restoration is therefore critical to restocking lost populations. This study
evaluates a two-phase restoration approach combining laboratory culture and suspended aquaculture to optimize
E. amentacea restoration, enabling multiple culture cycles within a single fertility window. Three experimental
conditions were tested: (A) 5 days in the laboratory followed by 12 days in suspended aquaculture, (B) 12 days in
the laboratory followed by 5 days in suspended aquaculture, and (C) 17 days in the laboratory without suspended
aquaculture. Culture performance was assessed in terms of coverage, length of individuals, and photosynthetic
efficiency. Results outlined that condition C achieved the best performance at the final time point. Condition B
showed intermediate outcomes, with length and photosynthetic efficiency comparable to condition C, but lower
coverage, with significant recovery post-outplanting. Condition A exhibited poor resilience, with declining
coverage and reduced photosynthetic efficiency. These findings suggest that a moderate reduction in laboratory
culture (12 days) may represent an effective trade-off between resource efficiency and germling development.
This approach is particularly relevant in the context of climate change, where shorter fertility periods and
extreme events challenge restoration efforts. This study highlights the potential of integrated laboratoryaquaculture
protocols to enhance the scalability and success of E. amentacea restoration, offering a promising
strategy for marine habitat recovery
COMPLEX WEAR MEASUREMENT ON THIN COATINGS BY THE CRATERING METHOD
No full textBall cratering and rotating wheel tests are useful techniques for abrasive wear resistence evaluation of thin coatings.
Nevertheless, such techniques involve significant experimental errors, coming from equipment deficiences and changes in wear response depending on test parameters.
In case of rotating wheel test, common instrumental errors are: geometry-induced errors (curved or non-horizontal sample surface), alignment errors (misalignment between ball/wheel axis and sample stage) and optical measurement errors.
In the present paper, errors due to crater dimension detection system (penetration depth or crater diameter) and equipment deficiences (rotating axes misalignment and sample slope) were numerically analysed.
A general expression form volume calculation was obtained, considering axes misalignment and sample slope, and experimentally validated by wear tests on Ti/TIN CAE-PVD coatings and profilometer abraded volumes measurement.
Results showed that axes misaligment and sample slope involve considerable errors in wear coefficient evaluation. However, errors can be corrected by the use of obtained expressions
The evolution of the Y-M scaling relation in MUSIC clusters
No full textThis work describes the baryon content and Sunyaev-Zeldovich properties of the MUSIC (Marenostrum-MultiDark SImulations of galaxy clusters) dataset and their evolution with redshift and aperture radius. The MUSIC dataset is one of the largest samples of hydrodynamically simulated galaxy clusters (more than 2000 objects, including more than 500 clusters). We show that when the effects of cooling and stellar feedbacks are properly taken into account, the gas fraction of the MUSIC clusters consistently agrees with recent observational results. Moreover, the gas fraction has a net dependence with the total mass of the cluster and increases slightly with redshift at high overdensities. The study of the Y-M relation confirms the consistence of the self-similar model, showing no evolution with redshift at low overdensities. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei
The MUSIC of galaxy clusters - I. Baryon properties and scaling relations of the thermal Sunyaev-Zel'dovich effect
No full textWe introduce the Marenostrum-MultiDark SImulations of galaxy Clusters (MUSIC) data set. It constitutes one of the largest samples of hydrodynamically simulated galaxy clusters with more than 500 clusters and 2000 groups. The objects have been selected from two large N-body simulations and have been resimulated at high resolution using smoothed particle hydrodynamics (SPH) together with relevant physical processes that include cooling, UV photoionization, star formation and different feedback processes associated with supernovae explosions. In this first paper we focus on the analysis of the baryon content (gas and star) of clusters in the MUSIC data set as a function of both aperture radius and redshift. The results from our simulations are compared with a compilation of the most recent observational estimates of the gas fraction in galaxy clusters at different overdensity radii. We confirm, as in previous simulations, that the gas fraction is overestimated if radiative physics are not properly taken into account. On the other hand, when the effects of cooling and stellar feedbacks are included, the MUSIC clusters show a good agreement with the most recent observed gas fractions quoted in the literature. A clear dependence of the gas fractions with the total cluster mass is also evident. However, we do not find a significant evolution with redshift of the gas fractions at aperture radius corresponding to overdensities smaller than 1500 with respect to critical density. At smaller radii, the gas fraction does exhibit a decrease with redshift that is related to the gas depletion due to star formation in the central region of the clusters. The impact of the aperture radius choice, when comparing integrated quantities at different redshifts, is tested. The standard, widely used definition of radius at a fixed overdensity with respect to critical density is compared with a definition of aperture radius based on the redshift dependent overdensity with respect to background matter density: we show that the latter definition is more successful in probing the same fraction of the virial radius at different redshifts, providing a more reliable derivation of the time evolution of integrated quantities. We also present in this paper a detailed analysis of the scaling relations of the thermal Sunyaev-Zel'dovich (SZ) effect derived from MUSIC clusters. The integrated SZ brightness, Y, is related to the cluster total mass, M, as well as, the M - Y counterpart which is more suitable for observational applications. Both laws are consistent with predictions from the self-similar model, showing a very low scatter which is σlog Y ≃ 0.04 and even a smaller one (σlog M ≃ 0.03) for the inverse M-Y relation. The effects of the gas fraction on the Y-M scaling relation are also studied. At high overdensities, the dispersion of the gas fractions introduces non-negligible deviation from self-similarity, which is directly related to the fgas-M relation. The presence of a possible redshift dependence on the Y-M scaling relation is also explored. No significant evolution of the SZ relations is found at lower overdensities, regardless of the definition of overdensity used
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