3,218 research outputs found
Modeling and Numerical Simulation of the Behavior of Charring Ablators During Atmospheric Re-Entry
No full textDuring the atmospheric entry of a blunt body, a bow shock wave is generated on the nose
of the vehicle, originating a zone at the wall where gaseous species are in thermochemical
non-equilibrium. In fact, the large kinetic energy of the flow is converted through
the shock into internal energy causing an increase in temperature, especially close to
the nose. The temperature rise occurring near the stagnation region may excite the
vibrational energy of the gas molecules and may also lead to dissociation and even to
ionization. Thus, a hypersonic flow is frequently a chemically reacting flow. Another
important high-temperature effect is the radiative heating from the flow to the body.
The most important consequence of high temperatures, from a technological point of view, is the resultant high heat transfer rates to the surface. Thus, in order to protect the vehicle's substructure against the
heat loads coming from the boundary layer, it is necessary to provide an accurate design
of the heat shield that has the task to isolate the interior of the space vehicle from the
high temperatures in the shock layer. Therefore, the accurate prediction of the thermal
response of the Thermal Protection System (TPS) is essential to accurately design the
heat shield with the aim of optimizing its thickness and shape.
Thermal protection systems able to endure
very high temperatures are made up of materials called surface ablators, that lose mass when subjected to
high thermal loads. There can be different causes of mass loss such as phase change,
chemical erosion, oxidation and mechanical removal. In general, the mass loss is part of a process called ablation through which the material rejects energy by means of a density variation. Another type of ablative materials are the so called charring or
decomposing ablators that undergo both surface ablation and in-depth decomposition. The surface
ablators are usually metals, graphite or carbon-carbon, while the charring ablators are resin/binder composites.
The main goal of this research has been the development of a computational tool able to accurately simulate the behavior of a non-reusable heat shield during the atmospheric re-entry of a space vehicle. The final tool can study both the behavior of the ablative thermal protection system and its interaction with the boundary layer through a strong coupling with a CFD solver.
The main features that can be considered during the computation are the decomposition of the resin and
the consequent generation of pyrolysis gas inside the pore space, in addition to the ablation phenomenon.
For instance, the pyrolysis effects related to the inner decomposition within a porous charring ablator can
be studied, including in-depth gas flux, porosity and pore pressure. This information can be used
to predict in-depth damage or mechanical removal caused by large pressure gradients
inside the pore spaces.
Our numerical simulation tool is also able to simulate
the recession of the material and different ablation models can be used to evaluate the recession rate at
the wall.
Moreover the ablators (unlike the ceramic tiles) strongly affect the flow field through the ablation phenomenon and the pyrolysis gas injection into the boundary layer. Consequently, the coupling with a Navier-Stokes
code allows us to study the gas/solid interaction at the wall
Cahier de voyage de Granada. Translations.
No full textThis research workshop, conducted over five days, aimed to propose an original interpretation of Granada through a dual perspective. Participants engaged in online discussions with local experts to gain historical and cultural insights, shaping the research question: How can Granada be visually depicted? During the on-site phase, participants document their impressions and experiences, collecting visual and textual data capturing the city's architectural, cultural, and sensory qualities.
The result is a physical artefact, a cahier de voyage inspired by artists' travel journals, specifically designed to convey the dual perspective of the two groups of designers involved in the making. Using techniques such as collage, cutting, and layering, the group crafted a tangible representation of Granada, inviting the viewer to explore the city's layered history and cultural significance
Lettera di Alessandra
No full textUn ritratto critico dell'opera di Alessandra Carnaroli, autrice fra le più apprezzate delle ultime generazioni della poesia di ricerca. La sezione a lei dedicata, nel numero della rivista, contiene inoltre saggi di Cecilia Bello Minciacchi, Andrea Cortellessa, e Ivan Schiavone; e vari inediti dell'autrice. Il saggio è pubblicato con lo pseudonimo di Tommaso Ottonieri.A critical portrait of the work of Alessandra Carnaroli, author of the most appreciated in the latest generations of italian research poetry. Published under the pseudonym Tommaso Ottonieri
Selected letters of Alessandra Strozzi
No full textThe letters of Alessandra Strozzi provide a vivid and spirited portrayal of life in fifteenth-century Florence. Among the richest autobiographical materials to survive from the Italian Renaissance, the letters reveal a woman who fought stubbornly to preserve her family's property and position in adverse circumstances, and who was an acute observer of Medicean society. Her letters speak of political and social status, of the concept of honor, and of the harshness of life, including the plague and the loss of children. They are also a guide to Alessandra's inner life over a period of twenty-three years, revealing the pain and sorrow, and, more rarely, the joy and triumph, with which she responded to the events unfolding around her.This edition includes translations, in full or in part, of 35 of the 73 extant letters. The selections carry forward the story of Alessandra's life and illustrate the range of attitudes, concerns, and activities which were characteristic of their author
Challenging the author: Gavin Douglas's Eneados
No full textGavin Douglas’s Eneados, a translation into the “Scottis” tongue of Virgil’s Aeneid, completed in 1513 and first published in London in 1553, presents, as well as the translation of the additional thirteenth book by Maphaeus Vegius, original prologues and marginal notes to the text, rubrics and articulate conclusive material. The present paper analyses this complex paratext as evidence of Douglas’s almost philological attention to the original and his preoccupation with a faithful reproduction; it is also suggested that the models for his organization of the commentary might be both medieval (i.e., manuscripts such as Petrarch’s Virgilius Ambrosianus) and early modern, as in the case of editions of classical works: the most apt example being Jodocus Badius Ascensius’ edition of the Aeneid, printed in 1501. The Eneados thus stands on the threshold between manuscript and print, and might have indicated new possibilities of use of the printing medium in Scotland, and of the value of the translation of a classical text, had history not intervened with the Scottish defeat at Flodden Fields in 1513, which put a temporary stop both to the circulation of the Eneados and to the development of Scottish printing
Building science and professional ethics in nineteenth-century ecclesiastical architecture in Malta
No full textAcknowledgement: The author would like to thank the late Rev. Paul Caruana for his help in the translation of the original sources from Italian into English and Alessandra Bianco for her assistance in gathering historical photographic material related to Mosta Church.This paper focuses on the Mosta Rotunda, the parish church of Mosta. Its construction started soon after the island became a colony. Its dome is an imposing architectural statement and a feat of building engineering structure in local masonry. Modelled on Hadrian’s Pantheon in Rome (118-128 AD), it has the third largest dome of any Christian church in Europe. It was designed in the Neoclassical idiom by the architect-engineer Giorgio Grognet de Vassé (1774-1862) who also supervised its construction. The aim of this paper is to demonstrate the building science and professional ethics underlying the design and construction of this outstanding nineteenth-century church.peer-reviewe
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