Search results for " materia"
showing 10 items of 18071 documents
Building the space: vaults’ geometry and stereotomy. Materials and architectural technologies in the Mediterranean area
2018
Costruire una volta ha sempre nei secoli rappresentato un’arte pratica che si nutriva del contributo di chi operava in cantiere: indispensabile risultava la tecnica, il sapiente taglio della pietra e l’opportuna collocazione della stessa nel gioco statico dell’organismo murario. Un sapere tecnico, questo, che combinava l’estetica con la organizzazione strutturale della fabbrica costruenda; l’esperienza pratica aveva dettato a muratori e scalpellini i precetti in merito ai differenti compiti organizzativi e alle relative gerarchie degli esecutori dell’opera edilizia, all’attrezzature e alle macchine da cantiere, agli utensili e alle lavorazioni da usare, incentivando una spiccata attitudine …
Photoluminescence and Electron Spin Resonance of Silicon Dioxide Crystal with Rutile Structure (Stishovite)
2018
This work was supported by ERANET MYND. Also, financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ/2017/2 realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. The authors express our gratitude to R.I. Mashkovtsev for help in ESR signal interpretation. The authors are appreciative to T.I. Dyuzheva, L.M. Lityagina, N.A. Bendeliani for stishovite single crystals and to K. Hubner and H.-J. Fitting for stishovite powder of Barringer Meteor Crater.
Toxicity of Dental Amalgams vs Composite Resins
2016
Ideal qualities of dental materials should include, in terms of biocompatibility, passivity towards oral tissues, so the material should not contain any leachable toxic and diffusible substances, neither release any harmful substance that can cause in time side effects, locally or generally. Even if amalgams are a group of dental materials with a long recorded history, many practitioners blame them, in contradiction with composite resins, especially for releasing free mercury into the body. On the other side, composite resins have reached great biocompatibility specifications, but also have many qualities that need more research, especially long term type.
Effects of integrating a bioethanol production process to a kraft pulp mill
2010
Abstract The integration of an ethanol production process based on prehydrolysis of softwood chips to a kraft pulp mill is discussed. A simulation model of this biorefinery has been created with WinGEMS simulation software to calculate the mass and energy balances of the biorefinery and to examine the effects of the integration on the operation of the pulp mill. Integrating the prehydrolysis process to the modeled pulp mill producing 1000 Adt/day of pine pulp would increase the wood consumption by 16%. With the increased wood consumption, 40 t/day of ethanol could be produced, and the excess power production could be increased by 460 MWh/day. The integration of the ethanol production proces…
A specific operative protocol set up during the restoration of the Grammichele slate slab
2009
This work deals with the conservation of a slate slab, representing the map of Grammichele, a small town in the hinterland of South Eastern Sicily. The slab was engraved and painted in 1693, just after the tremendous earthquake that distroyed most of the towns in that area. The conservation process is illustrated through three steps: i) archive research; ii) physical chemical analysis of constitutive materials and degradation products; iii) planning and carrying out of the restoration and conservation operations.
A compliance style of enforcement: il gusto di rispettare le regole
2008
Di fronte alla consapevolezza della complessità, varietà ed incertezza del tema ambiente e della sua tutela non è parso più possibile individuare strumenti e soluzioni ideal-tipici, espressi dalla legge, validi a prescindere dal tempo in cui vengono impiegati e dal contesto su cui insistono, e frutto in ogni caso della elaborazione unilaterale del legislatore. Da qui un articolato e diffuso movimento di ripensamento del tradizionale sistema di regolazione di matrice pubblicistica in materia ambientale indicato solitamente con il sintagma command and control, in base al quale le tre funzioni principali del processo di regulation (fissazione degli standard di condotta dei soggetti regolati – …
Comportement en fatigue des composites en lin/époxy
2011
International audience; Le travail présenté s'intéresse à la caractérisation des propriétés mécaniques quasi-statiques et en fatigue d'un composite stratifié en lin/époxy. Les éprouvettes fabriquées par thermocompression ont des séquences d'empilement de 0/90° et ±45° pour les essais de traction uniaxiale et cisaillement plan respectivement. Les essais quasi-statiques révèlent une variabilité des propriétés mécaniques de l'ordre de 10%. Les essais de fatigue en traction et en cisaillement plan ont été réalisés pour des niveaux de contraintes compris entre 40 et 80% des valeurs ultimes du composite (US). L'étude des boucles d'hystérésis a mis en évidence une plastification plus importante en…
Straw as a contemporary biomaterial: energetic efficiency and enviromental sustanaibility
2016
Questo studio ha lo scopo di segnalare ricerche e applicazioni in ambito costruttivo europeo e non solo della paglia, con particolare attenzione all'efficienza energetica e al comfort abitativo. Il riciclo e riutilizzo dei materiali naturali sono gli obiettivi principali nella scelta di paglia come materiale da costruzione, consentendo di adottare un approccio metodologico complessivo, che potrebbe prendere in considerazione l'intero edificio del ciclo di vita. Partendo dalla storia dell'utilizzo di paglia nella costruzione edilizia, saranno riportati molti esempi di edifici che utilizzano tale materiale all'interno del loro involucro e struttura. Le caratteristiche principali della paglia …
Inconsistencies in the pozzolanic strength activity index (SAI) for silica fume according to EN and ASTM
2014
Published version of an article in the journal: Materials and Structures. Also available from the publisher at: http://dx.doi.org/10.1617/s11527-014-0457-6 Open Access New supplementary cementitious materials claimed to possess pozzolan properties emerge frequently. This development is driven both by economic and environmental pressures. Properties of new materials are compared with those of materials already well known, such as silica fume. Several test methods are standardized for making such comparisons, regulated by both European (EN) and American (ASTM) standards. Standardization indicates that procedures are secured to make comparisons valid and informative. In this article the sensit…
The effect of defect location on coating fragmentation patterns under biaxial tension
2005
Fragmentation of a coating possessing orthogonal preferential crack propagation directions is modeled for equibiaxial tensile loading. Two plausible cracking scenarios are compared, caused by flaws randomly distributed over the area of the coating or along the coating fragment edges. The two fragmentation scenarios considered are shown to yield qualitatively different fragment patterns.