Search results for "upe"
showing 10 items of 7447 documents
Saturated Solutions of Anhydrous Phases in the System Lime-Silica-Water: Example of beta-C2S
1990
Saturated solutions rerely form when the anhydrous constituents of aluminous and portland cement are stirred in water or in lime solutions of increasing concentrations. Apart from monocalcium aluminate, concentration of ions in solution cannot exceed maximum supersaturation with respect to the hydrate most likely to precipitate. The present work shows such a behavior for β-C2S suspended in water and in lime solutions at low concentration. In more concentrated lime solutions, a short lifetime saturation state with respect to β-C2S seems to be reached.
Changes in Cement Paste and Mortar Fluidity after mixing induced by PCP: A parametric study
2006
International audience; The interaction mechanism between polycarboxylate-type superplasticizer (PCP) and cement hydration is not fully understood and incompatibilities between concrete and additive are sometimes observed. In some cases, the fluidity tends to increase (“overfluidification”) few minutes after mixing. This is a problem because the overfluidification leds to bleeding of the concrete which could be critical on job site. Our study consisted first in highlighting the phenomenon of “over-fluidification” by slump flow tests on mortar. Next, the time evolution of the rheological behaviour of cement pastes in the presence of PCP was analysed thanks to a rheometry protocol in order to…
Modification of the rate of formation and surface area of ettringite by polycarboxylate ether superplasticizers during early C3A–CaSO4 hydration
2015
Abstract Early C3A–CaSO4 hydration was studied in the presence of various amounts of two polycarboxylate ether superplasticizers differing in their grafting degree. Hydration and surface area developments were investigated by in-situ NMR relaxometry coupled with BET and DSC during the first 2 h after mixing. This study enables a quantitative comparison of the amount and the specific surface area of the ettringite precipitated along the C3A–CaSO4 hydration with or without PCE. The main effect of PCE is to strongly increase ettringite specific area for a variable period. These effects are clearly dependent on the PCE charge and dosage and are reduced when using delayed addition. In this conte…
Color Doppler ultrasonography of the eye and orbit
1993
Color Doppler imaging is the recent development in ultrasonography that allows simultaneous two-dimensional structural imaging in Doppler evaluation of blood flow. With this technique, it is possible for the first time to indirectly display the fine orbital vessels such as the ophthalmic artery and its branches, the central retinal artery, the posterior ciliary artery, and the lacrimal artery. Also, the display of venous structures such as the superior ophthalmic vein, the vortex vein, and the central retinal vein is possible. In addition to the qualitative display of those vessels, the hemodynamics in those vessels can be quantitatively assessed by looking at the Doppler spectrum and deter…
L'intervento nei centri storici: uno sguardo al quadro normativo
2022
Il contributo, ripercorrendo la produzione legislativa emanata sul tema dell’intervento nei centri storici dalla Regione Siciliana dagli anni Settanta ad oggi, si sofferma in particolare sulla LR 13/2015 “Norme per favorire il recupero del patrimonio edilizio di base dei centri storici”, un provvedimento legislativo molto contestato in ambito accademico che, di fatto, costituisce un grave arretramento culturale e tecnico non tenendo in alcun conto gli avanzamenti metodologici sul tema dei centri storici a partire dalla Carta di Gubbio del 1960. Nell’intento di favorire il recupero dei centri storici, la legge si fa portatrice di una serie di semplificazioni, a partire dal ricorso a classifi…
Centri storici meridionali: verso quale futuro?
2020
Il contributo prende le mosse da una domanda di fondo, e cioè se i centri storici delle grandi e medie città meridionali, interessati da processi di recupero e di riqualificazione, possano sfuggire a un destino settoriale basato prevalentemente sull’eccellenza del patrimonio, sul turismo e sulle attività culturali o possano continuare a svolgere il ruolo di strutture urbane vitali, dotate di un mix di attività ordinarie e di funzioni, prima fra tutte, quella residenziale. L’intervento sui centri storici richiede un’ottica multidisciplinare integrata, che dalla visione complessiva dei problemi faccia discendere strategie per la conservazione e la rivitalizzazione urbana. The contribution sta…
Il recupero e la messa in valore della Judería di Segovia
2013
The Spanish town of Segovia, World Heritage Site, launched a process of valorisation of its historical centre, supporting conservation and musealisation of monuments as well as encouraging recovery of private houses, particularly in the Judería District. Here, thanks to the Program Área de Rehabilitación de Centro Histórico (ARCH), Segovians were encouraged to go back to the historical center. The Oficina Técnica de Rehabilitación coordinated activities and funding, promoted the participation of owners and entrepreneurs, sensitised citizens on the issues of cultural heritage. The results obtained in the Judería District were so good that ARCH has been adopting in the next district las Canon…
Imparare a vedere la città. Palermo tra Piano Programma e P.P.E.
2014
A più di trent’anni dalla mancata attuazione del Piano Programma, sembrano ormai maturi i tempi per una riflessione culturale più distaccata e meno influenzata dalle contingenze di carattere politico-ideologico che hanno condizionato le ultime scelte pianificatorie sulla città di Palermo. Nella controversa vicenda che vide quale protagonista il Piano Programma per il centro storico di Palermo, l’acquisizione della capacità di “vedere” la città per comprendere come essa è fatta al fine della sua modificazione, si pone come un passaggio centrale e necessario per un corretto approccio alle ipotesi di pianificazione. Il presente saggio, proprio a partire dalla natura della predetta capacità di …
The accuracy of three-dimensional rapid prototyped surgical template guided anterior segmental osteotomy
2019
Background Surgical guiding templates provided a reliable way to transfer the simulation to the actual operation. However, there was no template designed for anterior segmental osteotomy so far. The study aimed to introduce and evaluate a set of 3D rapid prototyping surgical templates used in anterior segmental osteotomy. Material and Methods From August 2015 to August 2017, 17 patients with bimaxillary protrusions were recruited and occlusal-based multi-sectional templates were applied in the surgeries. The cephalometric analysis and 3D superimposition were performed to evaluate the differences between the simulations and actual post-operative outcomes. The patients were followed-up for 12…
Computation of inverse functions in a model of cerebellar and reflex pathways allows to control a mobile mechanical segment.
2003
Abstract The command and control of limb movements by the cerebellar and reflex pathways are modeled by means of a circuit whose structure is deduced from functional constraints. One constraint is that fast limb movements must be accurate although they cannot be continuously controlled in closed loop by use of sensory signals. Thus, the pathways which process the motor orders must contain approximate inverse functions of the bio-mechanical functions of the limb and of the muscles. This can be achieved by means of parallel feedback loops, whose pattern turns out to be comparable to the anatomy of the cerebellar pathways. They contain neural networks able to anticipate the motor consequences …