Search results for "Steady state"
showing 10 items of 173 documents
Contaminant Intrusion through Leaks in Water Distribution System: Experimental Analysis
2015
Abstract This paper presents the results of experimental tests on the intrusion of contaminant through pipe cracks in water distribution network resulting from low/negative pressures. The tests were carried out on a looped distribution network at the University of Enna and were performed first producing a pressure transient that causes negative pressures then reproducing intermittent supply. A soluble contaminant was added to the water volume in the network through a pipe crack. Sampling of water volume was carried out in two nodes of the network and the contaminant concentrations were measured. It was showed that: the contaminant was drawn in and transported, in the first set of tests; the…
Analysis of the thermomechanical behavior of the IFMIF bayonet target assembly under design loading scenarios
2015
In the framework of the IFMIF Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) phase, ENEA is responsible for the design of the European concept of the IFMIF lithium target system which foresees the possibility to periodically replace only the most irradiated and thus critical component (i.e., the backplate) while continuing to operate the rest of the target for a longer period (the so-called bayonet backplate concept). In this work, the results of the steady state thermomechanical analysis of the IFMIF bayonet target assembly under two different design loading scenarios (a "hot" scenario and a "cold" scenario) are briefly reported highlighting the relevant indications…
Consideration of the formation of solids and gases in steady state modelling of crevice corrosion propagation
2007
Abstract One of the challenges in the simulation of crevice corrosion propagation is the rigorous treatment of non-aqueous species (gas or solids), since the appearance of a new phase in a crevice will automatically have an impact on its geometry. This paper presents a simple approach, where heterogeneous reactions are considered in a post-processing step, by determining the conditions of potential, external chemistry (pH, chloride, …) or geometry under which gas or solid phases could appear in the crevice. Thus, as function of these conditions, stability diagrams for the different phases that are liable to appear in an actively propagating crevice can be constructed. Such diagrams (e.g. di…
On the thermomechanical behavior of the European target assembly design of IFMIF-EVEDA lithium test loop under start-up transient scenarios
2013
Uncoupled thermomechanical transient analyses have been carried out to investigate the behavior of IFMIF-EVEDA lithium test loop bayonet backplate target assembly under two selected start-up transient operational scenarios. The first transient scenario considered foresees that the target assembly, starting from the initial uniform temperature of 50 C, is heated up uniquely by convective heat transfer with lithium, flowing from inlet to outlet nozzle at its reference nominal temperature and pressure, until its nominal steady state thermal field distribution is reached. The second transient scenario foresees, more realistically, that the target assembly, starting from the uniform temperature …
Oxygen Consuming Regions in EMT60/Ro Multicellular Tumour Spheroids Determined by Nonlinear Regression Analysis of Experimental PO2 Profiles
1987
Malignant cells can be studied in vitro, in a tumour-like microenvironment, by growing multicellular tumour spheroids in culture (Sutherland, McCredie and Inch, 1971). Franko and Sutherland (1979) utilized diffusion theory to explain the viable rim thicknesses of spheroids measured histologically. Without PO2 profiles, however, an unequivocal interpretation of their results was not possible. Systematic studies of the PO2 profiles in spheroids have since been made with oxygen microelectrodes by several groups (Carlsson et al., 1979; Kaufman et al., 1981; Mueller-Klieser and Sutherland, 1982a,b). Based on these measurements, new analyses utilizing diffusion theory are being developed to chara…
Phenomenology of colloidal crystal electrophoresis
2003
We studied the motion of polycrystalline solids comprising of charged sub-micron latex spheres suspended in deionized water. These were subjected to a low frequency alternating square wave electric field in an optical cell of rectangular cross section. Velocity profiles in X and Y direction were determined by Laser Doppler Velocimetry. The observed complex flow profiles are time dependent due to the combined effects of electro-osmosis, electrophoresis, crystal elasticity, and friction of the crystals at the cell wall. On small time scales elastic deformation occurs. On long time scales channel formation is observed. At intermediate times steady state profiles are dominated by a solid plug o…
Study of the thermo-mechanical performances of the IFMIF-EVEDA Lithium Test Loop target assembly
2012
Abstract Within the framework of the IFMIF R&D program and in close cooperation with ENEA-Brasimone, at the Department of Energy of the University of Palermo a research campaign has been launched to investigate the thermo-mechanical behavior of the target assembly under both steady state and start-up transient conditions. A theoretical approach based on the finite element method (FEM) has been followed and a well-known commercial code has been adopted. A realistic 3D FEM model of the target assembly has been set-up and optimized by running a mesh independency analysis. A proper set of loads and boundary conditions, mainly concerned with radiation heat transfer between the target assembly ex…
Fluorescence quenching by trapped charge carriers in N,N-dimethylaminobenzylidene 1,3-indandione films
2010
Effects caused by the applied voltage on the steady state and time-resolved fluorescence of vacuum evaporated N,N-dimethylaminobenzylidene 1,3-indandione films sandwiched between gold and aluminium electrodes were investigated and discussed. Fluorescence enhancement and quenching as well as the fluorescence band narrowing depending on the applied voltage have been observed. Fluorescence decay and recovery take place on a time scale of tens of seconds after voltage is switched on and off. Similar fluorescence decay also takes place after switching on the excitation light. These fluorescence changes are attributed to the exciton quenching by trapped charge carriers.
Optimization of the breeder zone cooling tubes of the DEMO Water-Cooled Lithium Lead breeding blanket
2016
Abstract The determination of an optimal configuration for the breeder zone (BZ) cooling tubes is one of the most important issues in the DEMO Water-Cooled Lithium Lead (WCLL) breeding blanket R&D activities, since BZ cooling tubes spatial distribution should ensure an efficient heat power removal from the breeder, avoiding hotspots occurrence in the thermal field. Within the framework of R&D activities supported by the HORIZON 2020 EUROfusion Consortium action on the DEMO WCLL breeding blanket design, a campaign of parametric analyses has been launched at the Department of Energy, Information Engineering and Mathematical Models of the University of Palermo (DEIM), in close cooperation with…
Probabilistic response of linear structures equipped with nonlinear damper devices (PIS method)
2008
Passive control introducing energy absorbing devices into the structure has received considerable attention in recent years. Unfortunately the constitutive law of viscous fluid dampers is highly nonlinear, and even supposing that the structure behaves linearly, the whole system has inherent nonlinear properties. Usually the analysis is performed by a stochastic linearization technique (SLT) determining a linear system equivalent to the nonlinear one, in a statistical sense. In this paper the effect of the non-Gaussianity of the response due to the inherent nonlinearity of the damper device will be studied in detail via the Path Integral Solution (PIS) method. A systematic study is conducted…