Nel nome di Omar. Clero, rivoluzione e potere in Iran

Il lento coinvolgimento in politica del clero iraniano dalla fine del XIX secolo alla rivoluzione del 1979. Il pensiero e l'operato di Ruollah Khomeini. L'istituzionalizzazione della rivoluzione "islamica" nel corso della guerra Iran-Iraq 1980-1988. Le presidenze Rafsanjani, Hatami, Ahmadineja

Improvement of productivity, through a simulation model, in the production process of an alimentary pasta firm

Obiettivo del presente lavoro \ue8 trovare delle metodologie per migliorare un particolare aspetto del processo di produzione della pasta alimentare che, a seguito di un cambiamento del programma di produzione settimanale, subisce una diminuzione della produttivit\ue0 totale. Si \ue8 perci\uf2 realizzato un modello logico-matematico, che rappresentasse il sistema reale, mediante un programma di simulazione sul quale, dopo la validazione, sono stati realizzati una serie di esperimenti che hanno consentito, apportando delle modifiche all\u2019algoritmo di gestione del carico-scarico dei silos fra le fasi di produzione e confezionamento della pasta corta, di risolvere il problema

CFD analysis of port water injection in a GDI engine under incipient knock conditions

This paper investigates, through computational fluid dynamics (CFD) simulations, the knock resistance improvements that can be obtained in a turbo-charged GDI engine with water injection. In a first step, water and gasoline injector models are validated comparing the results with experimental data from constant volume chamber tests. Then, multi-cycle simulations are performed using the G-equation turbulent combustion model focusing on spray evolution and wall film dynamics. The main intent is analyzing the effectiveness of different water injection timings and injection pressures in a port water injection (PWI) installation. Combustion rates are validated against experimental engine data, with and without water injection. Afterwards, in order to predict autoignition behavior with different spark advance (SA) timings, the extended coherent flamelet model (ECFM) combined with a tabulated kinetic ignition (TKI) dataset is used. End-gas autoignition delays are calculated using a reduced mechanism for toluene primary reference fuel (TPRF), which revealed essential for capturing actual gasoline ignition characteristics. Results indicate that the water atomization quality, i.e., injection pressure, is significant in a PWI installation allowing a reduction of the water wall film formation in the ports. Water injection timing needs also to be carefully chosen for optimized performance. As the injected water allows the SA to be increased, the overall benefits on indicated mean effective pressure and fuel consumption are quantified under the same knock safety margin, matching adequately well the available measurements

Development and software in the loop validation of a Model-based water injection combustion controller for a GDI TC engine

Turbocharged (TC) engines work at high Indicated Mean Effective Pressure (IMEP), resulting in high in-cylinder pressures and temperatures, improving thermal efficiency, but at the same time increasing the possibility of abnormal combustion events like knock and pre-ignition. To mitigate knocking conditions, engine control systems typically apply spark retard and/or mixture enrichment, which decrease indicated work and increase specific fuel consumption. Many recent studies have advocated Water Injection (WI) as an approach to replace or supplement existing knock mitigation techniques. Water reduces temperatures in the end gas zone due to its high latent heat of vaporization. Furthermore, water vapor acts as diluent in the combustion process. In this paper, the development of a novel closed-loop, model-based WI controller is discussed and critically analyzed. The innovative contribution of this paper is to propose a control strategy based on an analytical combustion model that describes the relationship between the combustion phase and the Spark Advance (SA), considering also the effects of the injected water mass. Such model is calibrated with experimental data acquired during dedicated experimental tests on a GDI TC engine, equipped with a prototype Port Water Injection (PWI) system. At first the WI setup is described, and the main experimental data are presented and processed for model identification. Two algorithm versions are then explained in detail and implemented in Simulink environment, with a Real-Time (RT) oriented approach. In the last part of this work, the WI control strategy is tested in a Software in the Loop (SiL) system, coupled with a one-dimensional Fast Running Engine Model (FRM). The controller is tested on several engine points in steady state and transient conditions and the Root Mean Squared Error (RMSE) is calculated for the control targets. In this way, the performance of the model-based controller is verified, and the two versions of the algorithm are quantitatively compared

Stratifying the risk of developing atrial fibrillation after coronary artery bypass graft surgery using heart rate asymmetry indexes

Heart period (HP) asymmetry (HPA) is a peculiar pattern detectable over short-term HP variability recordings suggesting that cardiac deceleration runs are shorter than acceleration ones in healthy subjects. We tested the hypothesis that two traditional HPA indexes, namely the Porta's index (PI) and Guzik's index (GI), can distinguish patients scheduled for coronary artery bypass graft (CABG) surgery developing atrial fibrillation (AF) after surgery from the ones who do not (noAF). HP was derived from the electrocardiogram in 130 patients scheduled for CABG before (PRE) and after (POST) the induction of general anesthesia. PI assesses the percentage of positive HP changes, while GI quantifies the percent sum of the squared positive variations. Positive departures from 50 suggest that a series exhibits HPA. Surrogate analysis was exploited to assess the significant presence of HPA patterns. The likelihood of detecting HPA patters was higher in AF subjects and this result held during PRE. GI featured a greater statistical power than PI. Neither HP mean nor variance distinguished the two groups. HPA indexes can be exploited to improve stratification of the risk for post-surgery AF