117,534 research outputs found
PAESAGGI MINERARI.ARCHITETTURE E IMMAGINAZIONI TECNOLOGICHE PER COMPENDIO MONTEVECCHIO INGURTOSU PISCINAS
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Naval Ship Structures Exposed to Rocket Thermal and Pressure Loads
No full textThe present study is aimed to evaluate, by means of FEA, stresses and strains induced by thermal and pressure shock produced by rocket launch on the structures nearby SCLAR H system, installed on MMI’s NUM.
Preliminarly, in order to check the suitability of the numerical approach, for simple problems, a comparison was made between the heat transfer computed results and those obtained by analytical solutions, referring to transient heat conduction through a thin plate and through a semi-infinite solid.
Afterwards, the thermal analysis was performed by imposing on the exposed structures a surface temperature distribution experimentally known: the temperature through the thickness was determined.
Then, by means of a structural analysis, the thermal stresses, induced by the distribution numerically obtained by the previous computation, have been calculated.
As far as the pressure loads are concerned, adopting the peak values registered on the plates positioned next to the heat wave, a time/space dependent pressure mapping was evaluated.
The computations were performed by means of the software MSC/Patran and MCS/Nastran
The emergent gravity's entropy Ansatz from an augmented variational principle
No full textIn the last decade, physical and geometrical investigations about the relationship between horizon thermodynamics and gravitational dynamics suggest that gravity could be an emergent phenomenon. Among the others, Padmanabhan's theory of "emergent gravity" focus on the concept of spacetime as an effective macroscopic description of a more fundamental microscopic theory ("atoms of spacetime") at the Planck scales, thus aiming to reconcile the large scale description of gravity and the small one of quantum physics. However, some mathematical aspects of this approach are still not clear as, for example, the derivation of Einstein equations from a suitable entropy functional (and not from an action as in standard General Relativity). Thus in this work, a direct and non-trivial link between Padmanabhan's entropy used in emergent gravity and standard General Relativity action is established. To do that, Augmented Variational Principles and Kerr-Schild metrics will be used. We shall also discuss how this link accounts for the details of the variation of Padmanabhan's action based on gravitational entropy. It will also clarify the role of the background metric used in Padmanabhan's functional and its non-dynamical role
Isolation of Crithmum maritimum L. volatile oil by supercritical carbon dioxide extraction and biological assays
No full textThe chemical composition of the volatile concentrate obtained by supercritical CO2 extraction
of aerial parts of Crithmum maritimum L. growing spontaneously in one area of Mediterranean
coast (Buggerru, Sardinia Island, Italy) and in two areas of the Atlantic coast (Figueira da Foz
and S. Pedro de Moel, Portugal) was investigated by GC and GC-MS. The major oil
components identified were p-cymene, -phellandrene, -terpinene, thymol methyl ether and
dillapiole. The results showed the presence of two chemotypes of C. maritimum with different
dillapiole contents, ranging from 0.2 to 64.2% in Portuguese and Italian plants, respectively.
The minimal inhibitory concentration (MIC) and the minimal lethal concentration (MLC) were
used to evaluate the antifungal activity of the oils against yeasts and dermatophyte strains.
All the oils exhibited significant antifungal activity against dermatophyte strains. The oil with
the higher amount of dillapiole (64.2%) was the most active with MIC values ranging from
0.08–0.32 mLmL1
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