Search results for "IMPIANTI"

Scale-up and viscosity effects on gas–liquid mass transfer rates in unbaffled stirred tanks

2018

Abstract The interest in the process industry on unbaffled stirred tanks has greatly expanded in the last years because they may bring about significant advantages in a number of applications, including biochemical, food and pharmaceutical processes where the presence of baffles is undesirable for several reasons. Despite their application potential, unbaffled vessels still lack fundamental information, due to the fact that only recently their capabilities have started being dug out. The lack of information on scale up effects is possibly the main reason hindering practical applications. In this work the influence of vessel size and liquid viscosity on the mass transfer performance in unbaf…

Bartlett formalism generating functions and Z-transforms in fluctuation and noise theory

1983

Abstract “La theorie des fonctions generatrices s'adapte elle meme et avec la plus grande generalite aux questions des probabilite les plus difficiles.” (Laplace, 1812) “An important part of probability theory consists of the derivation of the probability distribution of the sum of n random variables, each of which obeys a given probability law, and the development of asymptotic forms of these distributions valid for increasing n. Probability generating functions owe their dominant position to the simplification they permit to both problems. Their employment to obtain the successive moments of a probability distribution and to solve the difference equations of probability theory is ancillar…

Statistical physics: Some basic principles of fluctuation and noise theory

1983

Abstract Models have traditionally played a significant role in statistical mechanics. In view of the complexity of the system which statistical mechanics attempt to describe, this is not at all surprising. The study of simplified models has frequently revealed the underlying mathematical structure of many physical questions and in so doing the study of models has contributed directly to a clarification of several paradoxes which beset statistical mechanics. In this paper some of the models which appear to be useful for the discussion of non-equilibrium phenomena are examined in some detail. As usual these models are extremely simplified versions of the actual situations. It is, finally, as…

Reduced graphene oxide decorated with metals nanoparticles electrode as electrochemical sensor for dopamine

2019

Dopamine (DA) is one of the most important neurotransmitters that influences the processes that involve memory, sleep, mood, learning among others [1]. In fact, in the last years, dopamine concentration in human body fluids has been related to some neurodegenerative diseases, such as Parkinson and Alzheimer's diseases [2]. The possibility to have a bio-marker for these disease is of extreme importance because, disease related with dementia, are diagnosed when they are already developed and their management become almost impossible. The possibility to continuously monitor DA level in fluids, such as blood and urine, could accelerate the early diagnosis of these diseases. The principal analyt…

A Monte Carlo study on the possible lay-out influence in the HCLL-TBM nuclear response

2008

A constitutive model for the thermo-mechanical behaviour of fusion-relevant pebble beds and its application to the simulation of HELICA mock-up exper…

2007

Abstract Within the framework of the R&D activities promoted by EFDA on the Helium-Cooled Pebble Bed Test Blanket Module to be irradiated in ITER, attention has been focused on the modelling of the thermo-mechanical behaviour of both beryllium and lithiated ceramic pebble beds that are envisaged to be used respectively as neutron multiplier and tritium breeder. This behaviour depends, mainly, on the reactor-relevant conditions, the pebble sizes and the breeder cell geometries and a general constitutive model has not yet been validated, especially for fusion-relevant applications. ENEA-Brasimone and the Department of Nuclear Engineering (DIN) of the University of Palermo have performed inten…

Risk assessment of component failure modes and human errors using a new FMECA approach: application in the safety analysis of HDR brachytherapy

2014

Failure mode, effects and criticality analysis (FMECA) is a safety technique extensively used in many different industrial fields to identify and prevent potential failures. In the application of traditional FMECA, the risk priority number (RPN) is determined to rank the failure modes; however, the method has been criticised for having several weaknesses. Moreover, it is unable to adequately deal with human errors or negligence. In this paper, a new versatile fuzzy rule-based assessment model is proposed to evaluate the RPN index to rank both component failure and human error. The proposed methodology is applied to potential radiological over-exposure of patients during high-dose-rate brach…

Safety study of an LNG regasification plant using an FMECA and HAZOP integrated methodology

2015

Abstract A safety analysis was performed to determine possible accidental events in the storage system used in the liquefied natural gas regasification plant using the integrated application of failure modes, effects and criticality analysis (FMECA) and hazard and operability analysis (HAZOP) methodologies. The goal of the FMECA technique is the estimation of component failure modes and their major effects, whereas HAZOP is a structured and systematic technique that provides an identification of the hazards and the operability problems using logical sequences of cause-deviation-consequence of process parameters. The proposed FMECA and HAZOP integrated analysis (FHIA) has been designed as a …

Analysis of a Station Black-Out transient in SMR by using the TRACE and RELAP5 code

2014

The present paper deals with the investigation of the evolution and consequences of a Station Black-Out (SBO) initiating event transient in the SPES3 facility [1]. This facility is an integral simulator of a small modular reactor being built at the SIET laboratories, in the framework of the R&D program on nuclear fission funded by the Italian Ministry of Economic Development and led by ENEA. The SBO transient will be simulated by using the RELAP5 and TRACE nodalizations of the SPES3 facility. Moreover, the analysis will contribute to study the differences on the code predictions considering the different modelling approach with one and/or three-dimensional components and to compare the capa…

RELAP5-3D thermal hydraulic analysis of the target cooling system in the SPES experimental facility

2014

The SPES (Selective Production of Exotic Species) experimental facility, under construction at the Italian National Institute of Nuclear Physics (INFN) Laboratories of Legnaro, Italy, is a second generation Isotope Separation On Line (ISOL) plant for advanced nuclear physic studies. The UCx target-ion source system works at temperature of about 2273 K, producing a high level of radiation (10^5 Sv/h), for this reason a careful risk analysis for the target chamber is among the major safety issues. In this paper, the obtained results of thermofluid-dynamics simulations of accidental transients in the SPES target cooling system are reported. The analysis, performed by using the RELAP5-3D 2.4.2 …