Developed Welfare

The task of addressing past and current needs, without delegating to either the market alone or the action of the public administration, enables new forms of collaboration, involving various parties, creating other modes of action between public and private cooperation

Oscillating Positive Expiratory Pressure on Respiratory Resistance in Chronic Obstructive Pulmonary Disease With a Small Amount of Secretion: A Randomized Clinical Trial

Abstract: This study aims to evaluate the acute effects of an oscillating positive expiratory pressure device (flutter) on airways resistance in patients with chronic obstructive pulmonary disease (COPD). Randomized crossover study: 15 COPD outpatients from Asthma Lab–Royal Brompton Hospital underwent spirometry, impulse oscillometry (IOS) for respiratory resistance (R) and reactance (X), and fraction exhaled nitric oxide (FeNO) measures. Thirty minutes of flutter exercises: a “flutter-sham” procedure was used as a control, and airway responses after a short-acting bronchodilator were also assessed. Respiratory system resistance (R): in COPD patients an increase in X5insp (-0.21 to -0.33 kPa/L/s) and Fres (24.95 to 26.16 Hz) occurred immediately after flutter exercises without bronchodilator. Following 20 min of rest, a decrease in the R5, [DELTA]R5, R20, X5, and Ax was observed, with R5, R20, and X5 values lower than baseline, with a moderate effect size; there were no changes in FeNO levels or spirometry. The use of flutter can decrease the respiratory system resistance and reactance and expiratory flow limitation in stable COPD patients with small amounts of secretions

Gas Exchange and Injection Modeling of an Advanced Natural Gas Engine for Heavy Duty Applications

The scope of the work presented in this paper was to apply the latest open source CFD achievements to design a state of the art, direct-injection (DI), heavy-duty, natural gas-fueled engine. Within this context, an initial steady-state analysis of the in-cylinder flow was performed by simulating three different intake ducts geometries, each one with seven different valve lift values, chosen according to an estabilished methodology proposed by AVL. The discharge coefficient (Cd) and the Tumble Ratio (TR) were calculated in each case, and an optimal intake ports geometry configuration was assessed in terms of a compromise between the desired intensity of tumble in the chamber and the satisfaction of an adequate value of Cd. Subsequently, full-cycle, cold-flow simulations were performed for three different engine operating points, in order to evaluate the in-cylinder development of TR and turbulent kinetic energy (TKE) under transient conditions. The latest achievements in open source mesh generation and motions were applied, along with time-varying and case-fitted inizialization values for the fields of intake pressure and temperature. Finally, direct-injection of natural gas in the cylinder was incorporated in full-cycle simulations, to evaluate the effects of injection on charge motions and charge homogeneity at the estimated spark timing. Three specific engine operating points were simulated and different combinations of turbochargers and valve lift laws were tested. Results consistency was verified by means of validations with data from 1D simulations and literature

CFD modeling and validation of spray evolution in gasoline direct injection engines

DOTTORATOIl presente lavoro si concentra sulla caratterizzazione numerica del processo di iniezione diretta di benzina tipico dei moderni motori ad accensione comandata per automobili. Una riproduzione dettagliata delle fasi di iniezione e miscelazione aria-combustibile è infatti un aspetto fondamentale per garantire un processo di combustione stabile, efficiente e con l'obiettivo di ridurre al minimo la formazione di inquinanti. In questo contesto, le simulazioni di termofluidodinamica computazionale rappresentano un potente strumento per valutare i principali fenomeni fisici correlati all'atomizzazione e all'evaporazione del getto di liquido che porta alla formazione della miscela mediante l'interazione tra il combustibile vaporizzato e i moti della carica aspirata. Per garantire l'accuratezza dei risultati numerici in modo che possano rappresentare un supporto affidabile per la progettazione industriale e le attività di ricerca, è fondamentale convalidare i sotto-modelli multidimensionali di spray con dati sperimentali disponibili in condizioni operative ben definite. A tal fine l'iniettore Spray G a iniezione diretta multi-foro di benzina, reso disponibile dall'associazione Engine Combustion Network, è stato scelto come geometria di riferimento per la convalida delle configurazioni numeriche proposte. Le simulazioni sono state condotte con il software open source OpenFOAM accoppiato alla LibICE, la quale rappresenta un insieme di librerie e solutori sviluppato dall'Internal Combustion Engine Group del Politecnico di Milano e dedicato alla riproduzione numerica dei più importanti fenomeni fisici legati ai motori a combustione interna. In questo lavoro una configurazione numerica di riferimento è stata testata su un'ampia gamma di condizioni operative relative allo Spray G, verificando i risultati in termini di penetrazione assiale dello spray, velocità del gas, interazione liquido-gas, morfologia dello spray e Sauter Mean Diameter (diametro medio). In questo contesto è stato possibile osservare i punti di forza e di debolezza dell'approccio e quindi, su tale base, proporre miglioramenti specifici. Un'innovativa metodologia di analisi della fase liquida, sviluppata per il Workshop ECN6 e basata su un campo Euleriano denominato "projected liquid volume", rappresenta l'approccio di validazione di riferimento utilizzato per valutare i miglioramenti ottenuti dai modelli di atomizzazione primaria e secondaria specificamente implementati nella LibICE nel corso del lavoro. Più in dettaglio, due soluzioni basate su un approccio disaccoppiato per la gestione di atomizzazione primaria e secondaria sotto un unico modello di spray sono state proposte e validate nel presente lavoro. Inoltre, un'evoluzione presente in letteratura di un classico modello di atomizzazione secondaria è stata implementata nella LibICE con l'obiettivo di fornire un approccio dinamico per breakup catastrofici e di stripping così che fosse possibile ottimizzare la riproduzione numerica dei processi di iniezione caratterizzati da condizioni di bassa evaporazione, tipici dei moderni motori a iniezione diretta di benzina. Sono stati inoltre implementati e validati su una specifica condizione operativa dello Spray G anche due modelli di evaporazione di tipo flash boiling disponibili in letteratura. I setup numerici proposti sono stati riprodotti anche in condizioni dinamiche eseguendo simulazioni di un ciclo completo di due moderni motori a iniezione diretta di benzina di tipo ad accesso ottico, uno dei quali direttamente accoppiato all'iniettore Spray G. Infine, il fenomeno fisico della collisione tra gocce liquide durante il processo di iniezione è stato studiato implementando nella LibiCE un modello di letteratura il cui scopo principale consiste in una riduzione del tempo di calcolo richiesto rispetto ad altri approcci disponibili. La convalida del modello è stata effettuata eseguendo diverse simulazioni Spray G e confrontando la penetrazione assiale di vapore e il diametro delle gocce calcolati con quelli resi disponibili senza collisione e da casi eseguiti adottando altri modelli di collisione già disponibili in OpenFOAM. Sulla base dei risultati ottenuti è stata poi proposta una modifica al modello in modo da poter raggiungere un migliore compromesso tra accuratezza numerica e minimizzazione del tempo di calcolo richiesto.The present work focuses on the numerical characterization of the gasoline direct injection process performed in modern spark-ignition engines for vehicle applications. A detailed prediction of injection and air–fuel mixing is in fact a mandatory task to guarantee a stable and efficient combustion process with the aim to minimize pollutant formation. Within this context, computational fluid dynamics simulations represent a powerful tool to assess the main physical phenomena related to breakup and evaporation of the liquid jet, leading to mixture formation by means of the interaction between the vaporized fuel and the charge motion. To ensure the accuracy of the computed results, so that they could be a reliable support for industrial design and research activities, it is mandatory to validate the adopted multidimensional spray sub-models against available experimental data under well-defined operating conditions. To this end, the multi-hole gasoline direct injection Spray G injector made available by the Engine Combustion Network community was chosen as the reference geometry for the validation of the proposed numerical setup. Simulations were carried out with the open source OpenFOAM software coupled with the LibICE framework which consists into a set of libraries and solvers developed by the Internal Combustion Engine Group of Politecnico di Milano and dedicated to the modeling of the most important physical phenomena related to internal combustion engines. In this work, at first a reference numerical spray setup was employed and tested under a wide range of Spray G operating conditions. By validating the results in terms of axial spray penetration, gas velocity, entrainment, spray morphology and Sauter Mean Diameter it was possible to observe strengths and weaknesses of the approach and thus propose specific improvements. An innovative liquid post-processing procedure, developed for the ECN6 Workshop and based on a projected liquid volume Eulerian field, represented the reference validation methodology for the proposed numerical improvements of atomization and secondary breakup which were implemented into the LibICE framework. More in detail, two solutions based on a decoupled approach for the management of primary and secondary atomization under a single spray model were proposed and validated in the present work. Furthermore, a literature-based evolution of a classic secondary breakup model was considered and implemented into the LibICE with the aim to provide a dynamic approach for droplet stripping and catastrophic breakup which could better suit the low-evaporating conditions of early injection events typical of modern gasoline direct injection engines. Two literature-based flash boiling evaporations models were implemented as well and validated on a dedicated Spray G flashing operating condition. The proposed numerical setups were also reproduced under dynamic conditions by performing simulations of a full-cycle of two modern gasoline direct injection optical access engines, one of which was directly coupled to the Spray G injector. Finally, the physical phenomenon of collision between liquid drops during the injection process has been studied by implementing into the LibICE framework a literature model whose main purpose was to reduce the required computational time compared to other available mechanisms. The validation of the model was carried out by running different Spray G simulations and by comparing computed axial vapor penetration and droplet diameter with those calculated without collision and with other dedicated models already available in OpenFOAM. On the basis of the observed results a further model modification was then proposed with the aim to achieve a better compromise between numerical accuracy and minimization of the required computational time.DIPARTIMENTO DI ENERGIA32ONORATI, ANGELODOSSENA, VINCENZ

CFD simulations of the steady state flow in modern cylinder heads for heavy duty Diesel engines

LAUREA MAGISTRALEIn questo lavoro di tesi il flussaggio stazionario della testa di un moderno motore Diesel è stato eseguito mediante l’utilizzo di tecniche di Fluido Dinamica Computazionale (CFD). Un’operazione di flussaggio stazionario può fornire informazioni molto importanti riguardo ai fenomeni che avvengono durante la fase di aspirazione di un motore reale, senza però essere soggetta a complessità di realizzazione dovute al moto del pistone e dei meccanismi correlati alle valvole. Ad oggi, la CFD rappresenta uno strumento essenziale per la risoluzione di problemi ingegnerestici ed è in grado di poter sostituire molte tipologie di test sperimentali. I risultati sperimentali relativi al flussaggio stazionario del motore Diesel in esame sono stati forniti da Fiat Power Train (FPT) assieme ai risultati delle rispettive simulazioni, eseguite per mezzo di un codice CFD commerciale molto diffuso (STAR-CCM+). In questo contesto, l’obiettivo del presente studio è stato quello di validare OpenFOAM (codice CFD open source utilizzato al Gruppo Motori a Combustione Interna del Politecnico di Milano per attività di ricerca) per il processo di flussaggio stazionario relativo allo specifico motore adottato per questo lavoro. Dopo un’introduzione teorica sulla fase di aspirazione dei reali motori Diesel a quattro tempi e sulle possibili diverse tipologie di moto della carica nel cilindro, prima di presentare le simulazioni eseguite durante il lavoro di tesi, vengono discusse le equazioni che governano i modelli CFD. In relazione alle simulazioni, è stato necessario creare la griglia di calcolo (mesh) per il tipo di motore in uso e, a tale scopo, sono stati utilizzati due differenti software open source, chiamati rispettivamente snappyHexMesh e cfMesh. Inizialmente sono stati calcolati i parametri specifcamente associati all’operazione di flussaggio stazionario (porata, coefficiente d’efflusso e intensità di swirl) mentre, in un secondo tempo, principale obiettivo dello studio è divenuta la verifica della conservazione del momento angolare associato al moto di swirl, imposto nel cilindro del motore durante la fase di aspirazione stazionaria. I risultati ottenuti con OpenFOAM sono stati infine confrontati con quelli raggiunti per mezzo di STAR-CCM+ e con i relativi valori sperimentali forniti da FPT. Infine, è stato importante riuscire a fornire, mediante OpenFOAM, risultati non solo affidabili ma anche ottenuti per mezzo di simulazioni poco costose dal punto di vista computazionale, e quindi eseguibili a livello industriale e commerciale.During this thesis work a Computational Fluid Dynamics (CFD) approach was chosen to simulate the steady state flow bench for a cylinder head of a modern heavy-duty Diesel engine. A steady state flow bench can provide very useful information regarding the phenomena occurring during the intake stroke of an operating engine, without incurring in complexities due to the movement of the engine piston and valves mechanism. CFD nowadays represents a valuable tool in engineering problems, capable even to replace many of the experimental tests. Experimental results related to the flow bench of the heavy-duty Diesel engine were provided by Fiat Power Train (FPT), along with simulations results achieved by means of a widely used commercial CFD code (STAR-CCM+). Within this context, the purpose of the thesis work was to validate the open source CFD OpenFOAM code (used at the Internal Combustion Engines Group of Politecnico di Milano for research activities) for steady state flow bench process of the specifically adopted engine geometry. After a theoretical introduction to the intake phase of operating four-stroke Diesel engines and to the different types of charge motions, the equations which govern a CFD model are discussed before that the simulations of the work are presented. About the latter, it was necessary to generate the computational grid (mesh) for the adopted engine and the programs used for this purpose are the open source snappyHexMesh and cfMesh. Initially, parameters specifically related to the engine flow bench (mass flow rate, discharge coefficient and swirl intensity) were evaluated, while the second step of the work was the computation of the angular momentum associated at the swirl flow, imposed in the cylinder engine during the flow bench process. The data obtained with OpenFOAM were finally compared with those achieved with STAR-CCM+ and with the experimental values provided by FPT. Lastly, it was important to provide reliable results for OpenFOAM by means of fast and cheap to run on an industrial and commercial scale CFD simulations

Psicosis clásica: diferentes momentos de su consideración en la obra freudiana

En la clínica prefreudiana, las referencias resultan desperdigadas y erráticas. Recién cuando Sigmund Freud se abocó al estudio del mecanismo específico de la neurosis y de la psicosis, esta última adquiere el carácter de una organización psicopatológica perfectamente delimitada. Por lo tanto, desde un análisis teórico de la obra, nos centraremos en el abordaje de la Psicosis en sus distintitos momentos, intentando comprender los puntos de inflexión y sus efectos. Con ese propósito, dividiremos expositivamente la consideración de la Psicosis en tres momentos. En cada uno, la referencia a la neurosis será casi obligada teniendo en cuenta que el interés de Freud surgió por la presencia de mecanismos defensivos, propios de la Neurosis Obsesiva, en algunas Psicopatías como la Paranoia y la Melancolía. Esto nos permitirá analizar, en la conclusión propuesta, qué modificaciones introdujo Freud a lo largo de su obra y cuáles fueron las consideraciones que se mantuvieron constantes en la etiología y nosografía de la Psicosis.From a theoretical analysis of the Freudian work we will focus on the approach of Psycho in its different moments, trying to understand the points of inflection and its effects. With this purpose we will expositoryly divide the consideration of psychosis in three moments, marking their particularities. In each, the reference to the neurosis will be almost obligatory considering that the interest of Freud arose by the presence of defensive mechanisms, typical of his Obsessive Neurosis, in some Psychopathies such as Paranoia and Melancholy. This will allow us to analyze, in the proposed conclusion, what modifications Freud introduced throughout his work, and what were the considerations that remained constant in the aetiology and nosography of Psycho.Mesas autoconvocadas: Psicología Clínica-Presentaciones clásicas y actuales de la psicosisFacultad de Psicologí

Dual black holes in merger remnants. I: linking accretion to dynamics

We study the orbital evolution and accretion history of massive black hole (MBH) pairs in rotationally supported circumnuclear discs up to the point where MBHs form binary systems. Our simulations have high resolution in mass and space which, for the first time, makes it feasible to follow the orbital decay of a MBH either counter- or co-rotating with respect to the circumnuclear disc. We show that a moving MBH on an initially counter-rotating orbit experiences an "orbital angular momentum flip" due to the gas-dynamical friction, i.e., it starts to corotate with the disc before a MBH binary forms. We stress that this effect can only be captured in very high resolution simulations. Given the extremely large number of gas particles used, the dynamical range is sufficiently large to resolve the Bondi-Hoyle-Lyttleton radii of individual MBHs. As a consequence, we are able to link the accretion processes to the orbital evolution of the MBH pairs. We predict that the accretion rate is significantly suppressed and extremely variable when the MBH is moving on a retrograde orbit. It is only after the orbital angular momentum flip has taken place that the secondary rapidly "lights up" at which point both MBHs can accrete near the Eddington rate for a few Myr. The separation of the double nucleus is expected to be around ~10 pc at this stage. We show that the accretion rate can be highly variable also when the MBH is co-rotating with the disc (albeit to a lesser extent) provided that its orbit is eccentric. Our results have significant consequences for the expected number of observable double AGNs at separations of <100 pc.Comment: 8 pages, 4 figures, revised version accepted to MNRA

Psicosis clásica: diferentes momentos de su consideración en la obra freudiana

En la clínica prefreudiana, las referencias resultan desperdigadas y erráticas. Recién cuando Sigmund Freud se abocó al estudio del mecanismo específico de la neurosis y de la psicosis, esta última adquiere el carácter de una organización psicopatológica perfectamente delimitada. Por lo tanto, desde un análisis teórico de la obra, nos centraremos en el abordaje de la Psicosis en sus distintitos momentos, intentando comprender los puntos de inflexión y sus efectos. Con ese propósito, dividiremos expositivamente la consideración de la Psicosis en tres momentos. En cada uno, la referencia a la neurosis será casi obligada teniendo en cuenta que el interés de Freud surgió por la presencia de mecanismos defensivos, propios de la Neurosis Obsesiva, en algunas Psicopatías como la Paranoia y la Melancolía. Esto nos permitirá analizar, en la conclusión propuesta, qué modificaciones introdujo Freud a lo largo de su obra y cuáles fueron las consideraciones que se mantuvieron constantes en la etiología y nosografía de la Psicosis.From a theoretical analysis of the Freudian work we will focus on the approach of Psycho in its different moments, trying to understand the points of inflection and its effects. With this purpose we will expositoryly divide the consideration of psychosis in three moments, marking their particularities. In each, the reference to the neurosis will be almost obligatory considering that the interest of Freud arose by the presence of defensive mechanisms, typical of his Obsessive Neurosis, in some Psychopathies such as Paranoia and Melancholy. This will allow us to analyze, in the proposed conclusion, what modifications Freud introduced throughout his work, and what were the considerations that remained constant in the aetiology and nosography of Psycho.Mesas autoconvocadas: Psicología Clínica-Presentaciones clásicas y actuales de la psicosisFacultad de Psicologí

Psicosis clásica: diferentes momentos de su consideración en la obra freudiana

En la clínica prefreudiana, las referencias resultan desperdigadas y erráticas. Recién cuando Sigmund Freud se abocó al estudio del mecanismo específico de la neurosis y de la psicosis, esta última adquiere el carácter de una organización psicopatológica perfectamente delimitada. Por lo tanto, desde un análisis teórico de la obra, nos centraremos en el abordaje de la Psicosis en sus distintitos momentos, intentando comprender los puntos de inflexión y sus efectos. Con ese propósito, dividiremos expositivamente la consideración de la Psicosis en tres momentos. En cada uno, la referencia a la neurosis será casi obligada teniendo en cuenta que el interés de Freud surgió por la presencia de mecanismos defensivos, propios de la Neurosis Obsesiva, en algunas Psicopatías como la Paranoia y la Melancolía. Esto nos permitirá analizar, en la conclusión propuesta, qué modificaciones introdujo Freud a lo largo de su obra y cuáles fueron las consideraciones que se mantuvieron constantes en la etiología y nosografía de la Psicosis.From a theoretical analysis of the Freudian work we will focus on the approach of Psycho in its different moments, trying to understand the points of inflection and its effects. With this purpose we will expositoryly divide the consideration of psychosis in three moments, marking their particularities. In each, the reference to the neurosis will be almost obligatory considering that the interest of Freud arose by the presence of defensive mechanisms, typical of his Obsessive Neurosis, in some Psychopathies such as Paranoia and Melancholy. This will allow us to analyze, in the proposed conclusion, what modifications Freud introduced throughout his work, and what were the considerations that remained constant in the aetiology and nosography of Psycho.Mesas autoconvocadas: Psicología Clínica-Presentaciones clásicas y actuales de la psicosisFacultad de Psicologí

High- and low-affinity PEGylated hemoglobin-based oxygen carriers: differential oxidative stress in a Guinea pig transfusion model

Hemoglobin (Hb)-based oxygen carriers (HBOCs) are an investigational replacement for blood transfusions and are known to cause oxidative damage to tissues. To investigate the correlation between their oxygen binding properties and these detrimental effects, we investigated two PEGylated HBOCs endowed with different oxygen binding properties - but otherwise chemically identical - in a Guinea pig transfusion model. Plasma samples were analyzed for biochemical markers of inflammation, tissue damage and organ dysfunction; proteins and lipids of heart and kidney extracts were analyzed for markers of oxidative damage. Overall, both HBOCs produced higher oxidative stress in comparison to an auto-transfusion control group. Particularly, tissue 4-hydroxynonenal-adducts, tissue malondialdehyde adducts and plasma 8-oxo-2'-deoxyguanosine exhibited significantly higher levels in comparison with the control group. For malondialdehyde adducts, a higher level in the renal tissue was observed for animals treated with PEG-Hboxy, hinting at a correlation between the HBOCs oxygen binding properties and the oxidative stress they produce. Moreover, we found that the high-affinity HBOC produced greater tissue oxygenation in comparison with the low affinity one, possibly correlating with the higher oxidative stress it induced