Search results for " confinement."
showing 10 items of 92 documents
Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating
2017
We describe a new technique for the efficient generation of high-energy ions with electromagnetic ion cyclotron waves in multi-ion plasmas. The discussed ‘three-ion’ scenarios are especially suited for strong wave absorption by a very low number of resonant ions. To observe this effect, the plasma composition has to be properly adjusted, as prescribed by theory. We demonstrate the potential of the method on the world-largest plasma magnetic confinement device, JET (Joint European Torus, Culham, UK), and the high-magnetic-field tokamak Alcator C-Mod (Cambridge, USA). The obtained results demonstrate efficient acceleration of 3He ions to high energies in dedicated hydrogen–deuterium mixtures.…
Experimental Investigation on the Compressive Behaviour of Clay Brick Masonry Columns Confined by BFRP or Steel Wires
2016
This paper presents the results of an experimental research aiming to investigate on the compressive behavior of full size clay brick masonry columns reinforced with Basalt Fiber Reinforced Cementitious Matrix (BFRCM) or with steel wires collaring. Uniaxial compressive tests were performed on eight retrofitted columns and four control specimens. Two masonry strength were considered by varying the mortar grade. Results are presented and discussed in terms of axial stress-strain relationships, failure modes and crack patterns of the specimens tested up to failure. For the limit of investigated variables, comparisons with unreinforced specimens show the ability of these alternative techniques …
Analisi Sperimentale del Comportamento Ciclico di Elementi in Calcestruzzo a Bassa Resistenza Confinati con FRCM
2013
Vengono riportati i principali risultati di una campagna sperimentale finalizzata alla caratterizzazione della risposta sotto carichi assiali ciclici di colonne di calcestruzzo a bassa resistenza con sezione circolare, quadrata e rettangolare, rinforzate con fibre di carbonio immerse in matrice cementizia (CFRCM). Sono state condotte prove di compressione assiale su 30 campioni di altezza 600 mm, 10 a sezione cilindrica di diametro 300 mm, 10 quadrata di lato 200 mm, e 10 rettangolare di lato 200x400 mm. Le prove sono finalizzate a indagare gli effetti del carico ciclico, della forma della sezione, del raggio di curvatura degli spigoli e del numero di strati di tessuto di rinforzo sul legam…
Experimental results of RC columns strengthnened with Fiber Reinforced Cementitious Mortars
2012
The structural behaviour of reinforced concrete columns strengthened with a system made up of fibre nets embedded in an inorganic stabilized cementitious matrix was investigated. Specimens with circular and square cross-section were cast and subjected to monotonic uniaxial compression to investigate the efficiency of a Polypara-phenylene-benzo-bisthiazole (PBO) Fibre Reinforced Cementitious Mortars (FRCM) system in increasing both carrying capacity and ductility. The experimental results show that confinement with PBO fibre produced a noticeable increment in strength and ductility, though the low mechanical ratios of fibre considered were not always able to ensure hardening behaviour up to …
Overview of the JET results
2015
Since the installation of an ITER-like wall, the JET programme has focused on the consolidation of ITER design choices and the preparation for ITER operation, with a specific emphasis given to the bulk tungsten melt experiment, which has been crucial for the final decision on the material choice for the day-one tungsten divertor in ITER. Integrated scenarios have been progressed with the re-establishment of long-pulse, high-confinement H-modes by optimizing the magnetic configuration and the use of ICRH to avoid tungsten impurity accumulation. Stationary discharges with detached divertor conditions and small edge localized modes have been demonstrated by nitrogen seeding. The differences in…
A three-dimensional study of the onset of convection in a horizontal, rectangular porous channel heated from below
2012
Author's version of an article published in the journal: International Journal of Thermal Sciences. Also available from the publisher at: http://dx.doi.org/10.1016/j.ijthermalsci.2011.12.012 The onset of convection is studied in a rectangular channel filled with a fluid saturated porous medium, bounded above and below by impermeable isothermal walls at unequal temperatures and laterally by partially conducting walls. A three-dimensional linear stability analysis is carried out under the assumption of an infinite longitudinal channel length. Then, this assumption is relaxed in order to determine the threshold length for the three-dimensional convection to be the preferred mode at onset. Sens…
#Io resto a casa, Nuove forme dell’abitare domestico
2020
Le regolamentazioni igienico-sanitarie hanno influenzato da sempre le teorie urbanistiche, le trasformazioni delle città e le forme dell’abitare. Nell’attesa della soluzione medica, la risposta al Covid19 passa da considerazioni sugli spazi. I cambiamenti più immediati possono avviarsi dalla casa, con un pensiero poietico e in opposizione all’idea che tutto dipenda unicamente dalla tecnologia. Il ragionamento sullo spazio domestico implica la riflessione sui nuovi bisogni (che l’emergenza ha acuito) e sulla ricerca della qualità, con una revisione dei minimi dell’abitare. L’isolamento ha aperto lo sguardo a possibili paesaggi domestici e, se la casa è ancora principio dell’abitare, da essa …
Strength and ductility of RC jacketed columns: A simplified analytical method
2016
Abstract Reinforced concrete (RC) jacketing is a common method for retrofitting existing columns with poor structural performance. It can be applied in two different ways: if the continuity of the jacket is ensured, the axial load of the column can be transferred to the jacket, which will be directly loaded; conversely, if no continuity is provided, the jacket will induce only confinement action. In both cases the strength and ductility evaluation is rather complex, due to the different physical phenomena included, such as confinement, core–jacket composite action, preload and buckling of longitudinal bars. Although different theoretical studies have been carried out to calculate the confin…
Frictional effects in structural behavior of no-end-connected steel-jacketed RC columns: Experimental results and new approaches to model numerical a…
2017
Steel jacketing of reinforced concrete (RC) columns is a common retrofitting technique used to restore bearing and deformation capacity of buildings presenting structural deficiencies. For practical reasons, steel angles are in several cases arranged leaving a gap with the end beams or slabs. Despite this disconnection, the angles are still able to support a non-negligible portion of load because of the frictional forces developed along the column-angle contact interface. In these cases, the definition of computational numerical and analytical models for the assessment of reinforced cross sections becomes more complex and must be handled with care. The actual load-carrying capacity of the a…
RC column externally strengthened with RC jackets
2013
In this paper the behaviour in compression of RC columns externally strengthened with concrete jacketing is analysed and a cross-section analysis of the jacketed member under axial load and bending moment is developed. The focus was to study the effect of confinement of concrete jacket on concrete core and the behaviour of compressed bars with buckling effects. Some other important aspects such as shrinkage, creep, old to new concrete surfaces and bond split effects were not included in the model because: the use of thick non-shrink grout jacket and a well-roughened surface of old-to-new concrete was supposed; long term effects were included though corrective coefficients for monolithic beh…