Suchergebnisse

I diritti sociali e la loro tutela multilivello nei periodi di crisi economiche sono i principali temi su cui verte la tesi. Dopo aver fatto un'analisi dei diritti fondamentali nel sistema euro-unitario e delle conseguenze in termini di riduzione dei livelli di garanzia a seguito di politiche economiche restrittive adottate dai governi europei in occasione della crisi economico-finanziaria del 2008, lo studio passa ad esaminare i diritti sociali dapprima nel sistema dell'Unione europea con un approfondimento del cd. Pilastro europeo dei diritti sociali e successivamente nell'ordinamento italiano. La ricerca approfondisce il ruolo delle corti nazionali che attraverso l'utilizzo del bilanciamento di interessi e diritti coinvolti e del principio di proporzionalità hanno cercato di contemperare i diritti sociali con i vincoli di bilancio imposti dall'Unione europea. Viene inoltre dato molto rilievo all'analisi dell'evoluzione del "dialogo tra le Corti" che si è rivelato un potente strumento non solo nell'interpretazione uniforme del diritto nello spazio europeo ma anche nel sistema di tutela multilivello dei diritti sociali. Particolare attenzione è dedicata all'ordinamento italiano e al ruolo della Corte costituzionale quale garante della legittimità dell'attività del decisore politico in materia di diritti sociali che non possono essere compressi al di sotto del loro contenuto minimo essenziale pur essendo dei diritti finanziariamente condizionati. Il quadro che emerge dalla ricerca conferma l'esistenza di una tutela multilivello dei diritti sociali in Europa dove gli strumenti a tutela di tali diritti non si esauriscono al livello nazionale del singolo Stato.

[EN] In this paper an experimental investigation on the heating experienced by the fuel when it expands through the calibrated orifices of a diesel injector is carried out. Five different geometries corresponding to the control orifices of two different commercial common-rail solenoid injectors were tested. An experimental facility was used to impose a continuous flow through the orifices by controlling the pressures both upstream and downstream of the restriction. Fuel temperature was controlled prior to the orifice inlet and measured after the outlet at a location where the flow is already slowed down. Results were compared to the theoretical temperature increase under the assumption of adiabatic flow (i.e. isenthalpic process). The comparison points out that this assumption allows to predict the fuel temperature change in a reasonable way for four of the five geometries as long as the pressure difference across the orifice is high enough. The deviations for low imposed pressure differences and the remaining orifice are explained due to the low Reynolds numbers (i.e. flow velocities) induced in these cases, which significantly increase the residence time of a fuel particle in the duct, thus enabling heat transfer with the surrounding atmosphere. A dimensionless parameter to quantify the proneness of the flow through an orifice to exchange heat with the surroundings has been theoretically derived and calculated for the different geometries tested, allowing to establish a boundary that defines beforehand the conditions from which heat losses to the ambient can be neglected when dealing with the internal flow along a diesel injector. ; This work was partly sponsored by "Ministerio de Economía y Competitividad", of the Spanish government, in the frame of the project "Estudio de la interacción chorro-pared en condiciones realistas de motor", reference TRA2015-67679-c2-1-R. This support is gratefully acknowledged by the authors. ; Salvador, F.; Gimeno, J.; Carreres, M.; Crialesi Esposito, M. (2017). Experimental ...

[EN] It is widely acknowledged that the development of sprays in the near-field is of primary importance for the spray formation downstream, as it affects both the spray angle, as well as the intact core length. In this frame, the present work aims to study the effects of turbulence inlet boundary condition on the spray formation by means of Direct Numerical Simulations on a real condition at low Reynolds number. To this extent, the code Paris-Simulator has been used, while a digital filter-based algorithm was used in order to generate synthetic turbulence at the inlet boundary condition. The influence of turbulence intensity and lengthscale on the atomization process has been studied and analyzed through 3 simulation for which these parameters have been varied. The results clearly highlight how the atomization is heavily affected by the inlet turbulence configuration. An analysis of the different atomizing conditions has been conducted, aiming to understand how the variation introduced by the inlet boundary condition on the velocity field is affecting the local atomization dynamics. ; This work was partly sponsored by "Ministerio de Economia y Competitividad", of the Spanish Government, in the frame of the Project "Estudio de la interaccion chorro-pared en condiciones realistas de motor", Reference TRA2015-67679-c2-1-R. The author thankfully acknowledges the computer resources at MareNostrum (BSC) and the technical support provided by FI-2016-3-0031. ; Salvador, FJ.; Ruiz, S.; Crialesi Esposito, M.; Blanquer Espert, I. (2018). Analysis on the efects of turbulent inflow conditions on spray primary atomization in the near-field by direct numerical simulation. International Journal of Multiphase Flow. 102:49-63. https://doi.org/10.1016/j.ijmultiphaseflow.2018.01.019 ; S ; 49 ; 63 ; 102

[EN] Nozzle hydraulic performance has a significant impact on diesel spray development and combustion characteristics. Thus, it is important to understand the links between the nozzle geometry, the internal flow features and the spray formation. In this paper, a detailed analysis of the impact of the nozzle orifices inclination angle on its hydraulic performance is performed. For this purpose, three different nozzles with included angles of 90, 140 and 155 degrees are evaluated. Instantaneous injection rate and momentum flux are measured on a set of injector operating conditions (mainly injection pressure and discharge pressure). The results show that higher inclination angles lead to smaller mass flow and momentum flux at steady-state conditions, due to the higher losses at the orifice inlet. These losses are translated in lower both area and velocity coefficients. Nevertheless, the impact of this parameter is limited thanks to the counter-acting effect of the hydrogrinding process, which produces larger rounding radii at the orifice inlet as the included angle increases. Based on the experimental results, correlations of the discharge coefficient as a function of the Reynolds number are obtained and evaluated. (C) 2017 Elsevier Ltd. All rights reserved. ; This work was partly sponsored by "Ministerio de Economia y Competitividad", of the Spanish Government, in the frame of the Project "Estudio de la interaccion chorro-pared en condiciones realistas de motor", Reference TRA2015-67679-c2-1-R. ; Salvador, FJ.; López, JJ.; De La Morena, J.; Crialesi Esposito, M. (2018). Experimental investigation of the effect of orifices inclination angle in multihole diesel injector nozzles. Part-1-Hydraulic performance. Fuel. 213:207-214. https://doi.org/10.1016/j.fuel.2017.04.019 ; S ; 207 ; 214 ; 213

1060 1078 232 8 ; S ; [EN] The motion of the needle during the injection process of a diesel injector has a marked influence on the internal flow, the fuel characteristics at the nozzle exit, the spray pattern and the fuel-air mixing process. The current paper is focused on the computational study of the internal flow and cavitation phenomena during the injection process, with inclusion of the opening where the needle is working at partial lifts. This study has been performed with a homogeneous equilibrium model (OpenFOAM) customized by the authors to simulate the real motion of the needle. The first part of the study covers the analysis of the whole injection process with a moving mesh using the boundary conditions provided by a one-dimensional (1D) model of the injector created in AMESim. This 1D model has offered the possibility of reproducing the movement of the needle with real lift law and real injection pressure evolution during the injection. Thus, it has been possible to compare the injection rate profiles provided by OpenFOAM against those obtained both in AMESim and experimentally. The second part compares the differences in mass flow, momentum flux, effective velocity and cavitation appearance between steady (fixed lifts) and transient (moving mesh) simulations. The aim of this comparison is to establish the differences between these two approaches. On the one hand is a more realistic approach in its use of transient simulations of the injection process and where the needle movement is taken into account. On the other hand, is the use of steady simulations at partial needle lifts. This analysis could be of interest to researchers devoted to the study of the diesel injection process since it could help to delimit the uncertainties involved in using the second approach which is more easily carried out, versus the first which is supposed to provide more realistic results. The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: ...

Il volume tende all'esame approfondito del complessivo disegno regolatore oggi universalmente conosciuto come Jobs Act : di conseguenza, ripercorrere, come si cercherà di fare nelle pagine che seguono, la trama dell'opera e gli istituti introdotti o modfiicati dal legislatore significa riavvolgere l'ordito della riforma attorno ad un unico, forse immaginario, file rouge.