Search results for " diffusion"
showing 10 items of 521 documents
Ramon Llull: un canone tutto per sé
2020
Riassunto: Desta sorpresa l’uso, a volte persino spregiudicato, che Ramon Llull fa della letteratura a lui contemporanea. Il maiorchino e stato capace di riutilizzare, piegandoli ai suoi fini, i generi di maggior successo del suo tempo: il romanzo cavalleresco, la poesia lirica o le raccolte di exempla e di miracoli diventano cosi strumento per divulgare e far capire quello che per Llull era il “libro migliore del mondo per la conversione degli infedeli”, ossia la sua Arte. Nella rilettura che proponiamo di alcuni frammenti della sua opera porteremo alcuni esempi di come funziona questa conversione della letteratura in ancella dell’Arte lulliana, per poter capire quali sono le strategie del…
Turing Instability and Pattern Formation for the Lengyel–Epstein System with Nonlinear Diffusion
2014
In this work we study the effect of density dependent nonlinear diffusion on pattern formation in the Lengyel---Epstein system. Via the linear stability analysis we determine both the Turing and the Hopf instability boundaries and we show how nonlinear diffusion intensifies the tendency to pattern formation; in particular, unlike the case of classical linear diffusion, the Turing instability can occur even when diffusion of the inhibitor is significantly slower than activator's one. In the Turing pattern region we perform the WNL multiple scales analysis to derive the equations for the amplitude of the stationary pattern, both in the supercritical and in the subcritical case. Moreover, we c…
Effects induced by 4.7 eV UV laser irradiation on pure silica core multimode optical fibers investigated by in situ optical absorption measurements
2011
We investigated by in situ optical absorption measurements the effects induced by 4.7 eV UV laser irradiation on pure silica core optical fibers. Laser irradiation with 100 MWcm−2 laser intensity generates in the fiber E′ centers which partially decay after irradiation due to their reaction with diffusing H2. An absorption band peaked at 5.3 eV is observed to grow in the post-irradiation stage with a kinetics anti-correlated to the decay of the 5.8 eV band of the E′ centers. The defect absorbing at 5.3 eV is proposed to be formed by trapping on pre-existing precursors of hydrogen atoms made available by breaking of H2 on E′.We also show by repeated irradiation experiments that the 5.3 eV-ab…
DFT studies on catalytic properties of isolated and carbon nanotube supported Pd9 cluster–I: adsorption, fragmentation and diffusion of hydrogen
2009
The processes of adsorption, fragmentation and diffusion of hydrogen on a small palladium cluster have been investigated by means of DFT and DFT/MM approaches. These studies have been performed by considering a D(3h) symmetry Pd(9) in the isolated state as well as when supported on a portion of single-walled armchair(6,6) carbon nanotube. The hydrogen fragmentation process easily occurs on the bare Pd(9) cluster, involving energy barriers of 25-35 kJ mol(-1) and the drop in spin multiplicity on passing from the reactant to the product. The atomic hydrogen diffuses through the cluster atoms with energy barriers, which do not exceed 20 kJ mol(-1), with some positions clearly identifiable as t…
Bench-scale investigation of inclined dense jets
2005
In this work experimental data on the geometry of dense inclined jets issuing in a lab-scale glass rectangular tank are presented. The surrounding fluid was always tap water at room temperature while the dense jets were water solutions of NaCl. Four parameters were changed in the experiments, namely nozzle diameter and inclination, and jet density and flow rate. Jet trajectories were revealed by a colored tracer. Images of the jet were recorded by a digital camera and then further digitally processed, eventually resulting in a time-averaged tracer intensity field. All the jet geometrical parameters, once normalized, were found to be very well correlated to the densimetric Froude number. Mod…
Social Influence Maximization in Hypergraphs
2021
This work deals with a generalization of the minimum Target Set Selection (TSS) problem, a key algorithmic question in information diffusion research due to its potential commercial value. Firstly proposed by Kempe et al., the TSS problem is based on a linear threshold diffusion model defined on an input graph with node thresholds, quantifying the hardness to influence each node. The goal is to find the smaller set of items that can influence the whole network according to the diffusion model defined. This study generalizes the TSS problem on networks characterized by many-to-many relationships modeled via hypergraphs. Specifically, we introduce a linear threshold diffusion process on such …
Design, construction and operational results of a pilot plant for the treatment and valorization of pickling waste solutions
2021
An innovative hybrid technology for both minimizing the waste production and optimizing the pickling process through the continuous control of pickling baths composition has been proposed by means of a pilot-plant installed at the Tecnozinco Srl, Carini (PA) hot-dip galvanizing plant. The recovery process has been accomplished by coupling a diffusion dialysis (DD), where HCl is recovered, a membrane distillation (MD), where HCl is concentrated, and a reactive precipitation (RP), where metal ions are recovered as iron hydroxide and ammonium/zinc chloride solution, to be used in the fluxing baths of the plant. The pilot plant was commissioned and operated using synthetic HCl solutions first a…
Worldwide Diffusion of ISO 14001 Standard
2008
We conduct an empirical examination of national conditions that promote the diffusion of the ISO 14001 standard. Our estimates confirm earlier studies on several determinants. While environmental considerations are important in the diffusion of the ISO 14001 standard, we show that other factors play a significant role as well, such as the prior diffusion of ISO 9000 and the country’s education level. Our main contribution is to provide empirical evidence for the hypothesis that the participation of a country or an economic sector in the standard-setting process is a major driver of its future adoption of the standard.
MEMORIE DAGLI SCAVI PER UN'ARCHEOLOGIA DELLA LETTERATURA IN GESUALDO BUFALINO
2022
The essay reflects on the lexical dissemination of terms belonging to the metaphorical area of 'recovery,' 'rebirth,' and 'rediscovery' in Bufalino's work beginning with Diceria dell'untore, in order to try to demonstrate the legacy of a private experience, the one related to the writing of his dissertation during the years of war and illness, in the transfigured one of literary reworking.
Role of apparent diffusion coefficient values in prostate diseases characterization on diffusion-weighted magnetic resonance imaging.
2019
BACKGROUND: To evaluate if normal and pathological prostate tissue can be distinguished by using apparent diffusion coefficient (ADC) values on magnetic resonance imaging (MRI) and to understand if it is possible to differentiate among pathological prostate tissues using ADC values.METHODS:Our population consisted in 81 patients (mean age 65.4 years) in which 84 suspicious areas were identified. Regions of interest were placed over suspicious areas, detected on MRI, and over areas with normal appearance, and ADC values were recorded. Statistical differences between ADC values of suspicious and normal areas were evaluated. Histopathological diagnosis, obtained from targeted biopsy using MRI-…