1,721,013 research outputs found
Problemi di Fisica Generale Meccanica - Termodinamica
No full textLibro di esercizi di meccanica e termodinamica per studenti di Ingegneri
Hydrogen sorption kinetics of magnesium hydride enhanced by the addition of Zr8Ni21 alloy
No full textHydrogen absorption and desorption kinetics, and thermodynamics of MgH 2 ball milled with addition of the Zr 8Ni 21 alloy have been studied. Different additive amounts were used from 3 to 12.5 wt%. The highest reversible capacity of 6.5 wt% of hydrogen was found for the samples with 3 and 5 wt% of additive. The best reaction kinetics was found with 10 wt% of additive: 5.9 wt% H 2 was desorbed in 4 min at 300 °C and 0.1 bar of hydrogen pressure. Regardless of the different storage capacities, all the samples were almost fully hydrided in 1 min using a hydrogen pressure of 10 bar at 250 and 300 °C. The enthalpy of formation of magnesium hydride was not affected by the presence of the additive.Fil: Pighin, Santiago Alberto. Università di Padova; Italia. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Capurso, Giovanni. Universita Di Padova. Dept.di Ingeniería Meccanica; ItaliaFil: Lo Russo, Sergio. Università di Padova; ItaliaFil: Peretti Hollemaert, Hernán Américo. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Gerencia de Investigación Aplicada; Argentin
Effects of surface and bulk transverse fields on the critical behaviour of ferromagnetic films
No full textThe influence of surface and bulk transverse fields on the critical behaviour of ferromagnetic Ising films is studied by using effective field theory based on a single-site cluster method. Surface exchange enhancement is considered and a critical value is obtained. The,dependence of the critical uniform transverse field on the film thickness, the phase diagrams in the fields, the critical surface transverse field versus the bulk one, and the exchange coupling ratio is presented
Ferromagnetic transitions of a spin-one Ising film in a surface and bulk transverse fields
No full textUsing the effective field theory method, we have calculated the Curie temperature of a spin-one Ising ferromagnetic film in a surface and bulk transverse fields. Numerical calculations give phase diagrams under various parameters. Surface exchange enhancement is considered. The dependence of the critical transverse field on film thickness, and phase diagrams in the fields, critical surface transverse field versus the bulk one are presented
The problem of solid state hydrogen storage
No full textAbstract
A short review of the materials under investigation suitable for solid state hydrogen storage is presented, with particular reference to the experimental activity carried out at the laboratory of Hydrogen Group of Padova University
Multilayer adsorption of gases in solids
No full textAdsorption phenomena of gas in solids are investigated using the Ono-Kondo lattice model. Layer concentrations rho(n) (n = 1, 2,... L) and Gibbs adsorption Gamma are presented versus the bulk density rho(b) and temperature. It is found that the density in core region (inner layers) and the density of the first layers next to the walls exhibit an opposite temperature dependence: while the density near the walls increases with decreasing temperature the density of the core region decreases to reach rho(b) as T increases. The density profile of the layers is also presented
The structural change of graphene oxide in a methanol dispersion
No full textGraphene oxide is a derivative of graphene which contains oxygen domains. Its debatable structure depends on the specific functional groups bonded to the graphene basal plane which have an impact on its reactivity. Here, we report the influence of methanol which affects the functionalization of pristine graphene differently to water
On the question of whether ion-beam mixing of Fe-Al and Mo-Cr multilayers is governed more nearly by ballistic effects, residual defects, or thermal-spike effects
No full text
Hydrogen sorption properties of vanadium- and palladium-implanted magnesium films
No full textAbstract
Magnesium films prepared by vacuum evaporation were implanted with vanadium and palladium ions in order to study their hydrogenation characteristics. It was found that the hydrogenation kinetics depend on the ion species and on the ion dose implanted. Indeed, the vanadium-implanted magnesium films have faster kinetics than the palladium-implanted ones. However, low vanadium concentration (∼0.3 at.%) seems to inhibit the absorption reaction. Among the ion-implanted magnesium films, the fastest kinetics were obtained with the vanadium-implanted film at a dose of 1×1016 ions/cm2: at 623 K and under a hydrogen pressure of 10 bar, a concentration of 6 wt.% of hydrogen was reached in 270 min during the first hydrogenation and in 45 min during the second one
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