Confined Impinging Jets: An alternative approach to traditional food emulsification techniques

In the food sector, the development of innovative manufacturing technologies represents an exciting area of research. Within this context, Confined Impinging Jets (CIJs) offer potential for the large throughput production of tailored emulsion-based microstructures at lower energy inputs than conventional emulsification routes. Overall, this thesis aims to demonstrate that CIJs can be considered as a reliable alternative to existing emulsification methods by assessing its processing capacity and performance in delivering emulsion-based microstructures from a wide range of different formulations. The use of CIJs was initially explored for the production of emulsions with dispersed phase contents of up to 80 wt.%, in both a surfactant-poor and surfactant-rich regime, under varying mass jet flow rates, W$_{jet}$, and residence times. From both a computational and experimental study, it was observed that the CIJs emulsification capacity was strictly dependent on the mass jet flow rate (W$_{jet}$> 176 g/min) and the pre-emulsion droplet size (>10μm). CIJs emulsification performance remained (almost) unaffected by variations in the oil mass fraction. All systems showed the lowest droplet size (~8μm) and similar droplet size distributions under the highest W$_{jet}$. Conditionally onto the Tween20 availability, the emulsion d$_{3,2}$ was primarily determined by formulation characteristics in the surfactant poor-regime and by the CIJs energy dissipation rate in the surfactant-rich regime. CIJs emulsification performance was further assessed at varying energy dissipation rates (ε̅$_{th}$) and residence times for the production of 10 and 40 wt.% oil-in-water emulsions stabilised by an array of particles (Silica) and mixed emulsifier (Tween20-Silica) concentrations. Overall, it was demonstrated that droplet size reduction was promoted as higher energy levels of ε̅$_{th}$ were approached, regardless of the formulation. Following emulsion recirculation under a fixed jet mass flow rate, the residence time associated with two passes was sufficient to ensure no further changes in terms of both average droplet size (d$_{3,2}$) and span of the droplet size distribution. Only when Tween20 and Silica were mixed at low concentrations (0.01 and 0.1 wt.%, respectively), this emulsifier system could not promote any droplet size reduction even during multipassing. All systems showed excellent stability over 40 days of storage and it was possible to demonstrate that the combination of the emulsifiers aided in prolonging emulsion integrity. Finally, a comparison of the emulsification performance of CIJs with that of both high- (high pressure homogeniser, HPH; high-shear mixer, HSM) and low-energy (rotating membrane, RM) emulsification techniques was studied and compared based on a wide range of processing (average energy dissipation rate, ε̅$_{th}$; flow regime; energy density, Ev; and energy efficiency, EF) as well as formulation (dispersed phase content, and type of emulsifier) parameters. It was observed that during HPH, HSM and CIJs processing, emulsions were produced under a turbulent flow regime, contrarily to RM where the flow was laminar. The performance of the HPH was very much dependent on the type of emulsifier used, while all other techniques were practically unaffected by both emulsifier and oil phase content. Overall, the HPH treatment generated the highest ε̅$_{th}$ and comparable Ev to the HSM. The CIJs operated at intermediate ε̅$_{th}$ and Ev conditions, while RM exhibited the lowest values for both these parameters. CIJs and the RM were the most energy efficient processes. For all techniques (with the exception of RM where recirculation was not performed), emulsion recirculation (under fixed hydrodynamic conditions) significantly affected droplet size distribution but only marginally reduced d$_{3,2}$. However, increasing the residence time within the emulsification apparatus (via recirculation), strongly decreased the EF of all processing techniques. The CIJs still remained the most energyefficient method while HPH and HSM processing resulted in lower EFs with their relative values dependent on the type of emulsifier used

The Risk of Malignant Degeneration of Müllerian Derivatives in PMDS: A Review of the Literature

Persistent Müllerian Duct Syndrome (PMDS) is a rare autosomal recessive disorder of sex development characterized by the presence of fallopian tubes, uterus and upper one-third of the vagina in individuals with XY genotype and normal male phenotype. The main complications of PMDS are infertility and the rare risk of malignant degeneration of both testicular and Müllerian derivatives. We report the case of a 49-year-old man who, during repair of an incisional hernia, was incidentally found to have a uterine-like structure posterior to the bladder. In the past at the age of 18 months, he had undergone bilateral orchidopexies for bilateral cryptorchidism. The intraoperative decision was to preserve the uterine-like structure and make a more accurate diagnosis postoperatively. Evaluation revealed an XY chromosome and imaging consistent with PMDS. The patient was informed about the risk of neoplastic transformation of the residual Müller ducts and was offered surgical treatment, which he declined. Subsequent follow-up imaging studies, including testicular and pelvic ultrasound, were negative for findings suggestive of malignant testicular and Mullerian derivative degeneration. A review of the international literature showed that, when a decision is taken to remove the Mullerian derivatives, laparoscopy and especially robotic surgery allow for the successful removal of Müllerian derivatives. Whenever the removal of these structures is not possible or the patient refuses to undergo surgery, it is necessary to inform the patient of the need for adequate follow-up. Patients should undergo regular pelvic imaging examination and MRI might be a better method for that purpose

Numerical and analytical models for electromechanical motion systems.

This dissertation presents our contribution on the field of applied electromagnetism. Our work has mainly been focused on the design and modeling of devices exploiting magneto-mechanical properties (e.g. magnetic levitation (MagLev) systems, Electromagnetic Launchers (EML), electro-dynamic bearings). The numerical modeling of the problem has been designed through a low frequency integral formulation of the Maxwell equations coupled with the Newton Euler dynamics equations. The non-linear system has been solved wit different schemes, mainly based on predictor corrector approaches. A C framework exploiting GPGPU capability (Nvidia CUDA) has been developed and validated by comparison with experimental results or FEM simulations. A lot of interest has also been posed to the design of innovative electro-mechanical devices, that have been deeply analysed and simulated by the developed numerical formulation

Modelli numerici per sistemi elettromeccanici a sei gradi di liberta'.

Questo documento si propone di illustrare lo sviluppo di alcune estensioni del software Cad, atte a permettere lo studio del comporta- mento dinamico di sistemi elettromeccanici mediante una metodologia di tipo integrale. Il programma, scritto in linguaggio C, riceve in in- gresso la descrizione geometrica di un dispositivo e ne effettua una suddivisione in volumi elementari, i cui centri geometrici diventano i nodi di una rete elettrica equivalente. Quest’ultima viene risolta e una volta ottenute le correnti nei vari rami, é possibile ottenere la descri- zione dei campi magnetici e delle forze agenti sugli oggetti e quindi ottenere il comportamento dinamico degli oggetti in esame descriven- done il moto nello spazio. Per l’integrazione delle equazioni del moto è stato utilizzato un metodo di predizione e correzione, che si é dimo- strato robusto e accurato. Inoltre per ridurre il tempo di calcolo della procedura è stata sviluppata una parallelizzazione multi-threaded del codice, utilizzando le API Microsoft Win32. In una seconda fase, vie- ne svolta una procedura di valutazione numerica della metodologia, effettuando dei confronti con i risultati ottenuti con un software com- merciale (EFFE) su alcuni casi noti. La fase finale del lavoro, consiste nella creazione di alcuni modelli interessanti di cui studiare il compor- tamento mediante il software implementato: si tratta di un modello di un binario per un sistema a levitazione magnetica e di un model- lo di cuscinetto a magneti permanenti, entrambi sviluppati con una struttura ad Array di Hallbach

Modelli locali e modelli globali nella previsione dei ritardi di consegna dei fornitori: analisi di un caso studio nel settore automotive

L’obiettivo principale di una catena di approvvigionamento (“supply chain”) è quello di garantire che il consumatore finale ottenga prodotti o servizi nella maniera più efficiente possibile, cioè in tempi brevi e con un costo da sostenere minimo. Nel settore manifatturiero e, nello specifico, nel settore automotive - che è quello di interesse della presente tesi - tale catena di approvvigionamento sta assumendo negli anni una complessità crescente: uno dei fattori chiave è legato alla puntualità delle consegne da parte dei fornitori, che svolge un ruolo cruciale nel garantire la fluidità delle operazioni di produzione. In questa prospettiva, l’obiettivo dell’elaborato è quello di presentare un algoritmo di machine learning, il quale, sulla base di un insieme di dati appartenenti ad un’azienda che opera nel settore dell’automotive, calcola le previsioni circa il possibile ritardo o anticipo che può realizzarsi al momento della consegna di un certo prodotto da parte dei suoi abituali fornitori rispetto alla data originariamente prevista e fornisce delle valutazioni circa la bontà della previsione effettuata. Tale algoritmo lavora seguendo tre approcci: il primo approccio, rientrante nella famiglia dei metodi “locali”, fornisce una valutazione della previsione effettuata a livello di singolo fornitore e di singolo prodotto. Gli altri due approcci, invece, rientrano nella famiglia dei “metodi globali”: in particolare, il secondo approccio opera su un campo di azione lievemente più ampio rispetto al primo, giacché valuta la previsione a livello di singolo fornitore ma considerando tutti i suoi prodotti. Il terzo approccio, infine, effettua le previsioni e la relativa valutazione a livello di tutti i fornitori contenuti nel database. Tale tesi, dunque, si pone l’obiettivo di fornire linee guida pratiche per ottimizzare la catena di approvvigionamento nel settore automotive, promuovendo la puntualità delle consegne e migliorando l'efficienza operativa complessiva

The Double-Sided Tubular Linear Induction Motor and Its Possible Use in the Electromagnetic Aircraft Launch System

In this paper, a double-sided stator tubular linear induction machine is presented, and its performance is discussed for possible use as a catapult in the electromagnetic acceleration of aircraft. Based on the use of the Fourier transform in the direction of the motion, a semianalytical model that is able to take into account the end effects due to the finite length of the stators is derived. The effectiveness of the model has been proven by comparison with a numerical analysis based on the finite-element method. The reported results obtained using the two methods show excellent agreement that makes the proposed model a valuable tool for a preliminary design of the devic

Dynamics of a non-hysteretic superconductive passive magnetic linear bearing

In the present work the dynamical behavior of a magnetic levitating linear bearing suitable for working in the non-hysteretic range of forces is presented. The presented bearing device is composed of a high temperature superconductor with semi-cylindrical shape and a levitating slider made of a permanent magnet. Meissner repulsion forces of the superconductor provides stable equilibrium and restoring forces in 4 degrees of freedom (DOF), allowing the magnet to displace linearly along the axis of the superconducting semi-cylinder. A custom-made model based on numerical integration of coupled electromechanical equations has been developed, demonstrating good accuracy between the solution obtained and commercial FEM software ones. Radial and axial stiffness of the bearing have been calculated using this model. The vertical equilibrium as a stable position of the linear bearing displacement was found. Dynamical and transient simulation was done in order to determine the position of the levitating magnet for different external perturbations. Moreover, the calculation of the maximum pressures and thus the magnetic field applied for each position of the displacement proves that it can operate at 100 K or below. It can be assured that a complete Meissner state occurs; hence the displacement will be completely non-hysteretic. Such a non-hysteretic passive linear bearing can be very suitable for long-stroke precision positioning. The high translational symmetry of the magnetic field seen by the permanent magnet assures a usable long stroke of around ± 90 mm with full performance and ± 150 mm with reduced performance. This linear bearing in combination with an actuating system for only one DOF can be used for accurate precision positioning systems for cryogenic environments with zero hysteresis in the movement