Natura e architettura nel giardino di Villa Florio-Pignatelli (Palermo, Sicilia).

ABSTRACT.\u2013 Amongst the Sicilian historical gardens it is merited to remember the ornamental garden design of Villa Florio- Pignatelli, situated in the western periphery of Palermo. The building, and probably the garden too, are from the second half of the 18. century. This article contains the result of a cognitive study of its history, architecture and vegetal composition, based on field studies in the garden itself, on bibliographical and archival work. In 1838 it was sold by the Duke of Cumia to Vincenzo Florio, who in following conceded it to his son Ignazio. Already at this time, there was a garden with a "flora all\u2019Italiana" behind the Villa, which had circular vials in radial order, demarcated with a box-hedge (Buxus sempervirens), much like a small reproduction of the more famous and celebrated Villa Giulia (1777), the first public garden in the town.The elegance of the garden's proportions is based on at least four geometric orders interacting with each other. They reveal evi- dence of important fixed points or "topoi" of the garden; these affirm that the apparent simplicity contains complicated arith- metic and geometric relations in an exceptional union of architectural and botanical significance

Disentangling age and metallicity in distant unresolved stellar systems

We present some results of an observational and theoretical study on unresolved stellar systems based on the Surface Brightness Fluctuations (SBF) technique. It is shown that SBF magnitudes are a valuable tracer of stellar population properties, and a reliable distance indicator. SBF magnitudes, SBF-colors, and SBF-gradients can help to constrain within relatively narrow limits the metallicity and age of the dominant stellar component in distant stellar systems, especially if coupled with other spectro-photometric indicators.Comment: A contributed paper to the Cefalu' (Italy) "Probing Stellar Populations out to the Distant Universe", 4 pages. To appear as an AIP Conference Proceedin

Fast model predictive control for hydrogen outflow regulation in ethanol steam reformers

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In the recent years, the presence of alternative power sources, such as solar panels, wind farms, hydropumps and hydrogen-based devices, has significantly increased. The reasons of this trend are clear: contributing to a reduction of gas emissions and dependency on fossil fuels. Hydrogen-based devices are of particular interest due to their significant efficiency and reliability. Reforming technologies are among the most economic and efficient ways of producing hydrogen. In this paper we consider the regulation of hydrogen outflow in an ethanol steam reformer (ESR). In particular, a fast model predictive control approach based on a finite step response model of the process is proposed. Simulations performed using a more realistic non-linear model show the effectiveness of the proposed approach in driving the ESR to different operating conditions while fulfilling input and output constraints.Peer ReviewedPostprint (author's final draft

Thermal, mechanical and electrical performance of structural epoxy resins filled with carbon nanofibers

Carbon nanofibers (CNFs) were heat-treated at 1100 & DEG;C (CNF1100) and 2500 & DEG;C (CNF2500), respectively, and embedded as fillers at different mass percentages into an epoxy mixture. The paper aims at evaluating, through a comparison between the two different types of resulting nanocomposites, the influence of the CNF heat treatment on the thermal, mechanical, and electrical performance of the formulated samples. Thermogravimetric analysis (TGA) showed oxidative stability in the air of CNF2500 approximately 200 & DEG;C higher than the CNF1100 ones. The first oxidation stage of the resins embedding the two typologies of CNFs falls between 380 and 480 & DEG;C. This means that the temperature of the heat treatment of the nanofiller does not influence the temperature at which the thermodegradation of the nanocomposites starts. Differential Scanning Calorimetry (DSC) data show that the highest degree of cure (DC) was recorded for the epoxy samples filled with CNF2500. CNF thermal treatment increases the direct current (dc) conductivity of the nanocomposite by 3 orders of magnitude around the electrical percolation threshold (EPT) and increases the storage modulus of the CNF2500-based resins up to 60 & DEG;C compared with the unfilled resin. The peculiar wall structure of CNF1100 determines a further slight enhancement. Tunneling Atomic Force Microscopy (TUNA) reveals that the CNFs are evenly distributed on the nanodomains showing higher electric current values for samples loaded with CNF2500

Unsolved Problems about Supernovae

A number of unsolved problems and open questions about the nature and the properties of supernovae are identified and briefly discussed. Some suggestions and directions toward possible solutions are also considered.Comment: 7 pages, Proceedings of 'Probing Stellar Populations out to the Distant Universe', Cefalu, Italy, Sep 7-19, 2008, AIP Conf. Proc. Serie

Advances on GRB as cosmological tools

Several interesting correlations among Gamma Ray Bursts (GRB) prompt and afterglow properties have been found in the recent years. Some of these correlations have been proposed also to standardize GRB energetics to use them as standard candles in constraining the expansion history of the universe up to z>6. However, given the still unexplained nature of most of these correlations, only the less scattered correlations can be used for constraining the cosmological parameters. The updated E_peak-E_gamma correlation is presented. Caveats of alternative methods of standardizing GRB energetics are discussed.Comment: 8 parges, AIP conf. proc. "Probing stellar populations out to the distant universe, Cefalu' 2008" Vol. 1111, pp. 579-58