Studio, verifica ed ottimizzazione di una macchina automatica opercolatrice

“Perdita di fase tra il gruppo riempimento polvere/cronoidi con LVDT ed il gruppo piattello durante la fase di arresto a causa della mancanza imprevista di corrente elettrica”. La perdita della fase tra differenti gruppi può avvenire per due ragioni: 1) a causa della cedevolezza di alcuni elementi della catena cinematica 2) per problemi relativi al software che comanda gli assi elettronici e che è responsabile del movimento coordinato dei vari gruppi. La prima ipotesi è molto improbabile in macchine come l’ADAPTA, dove non sono presenti elementi cinematici con elevata cedevolezza (come ad esempio delle cinghie) essendo i movimenti guidati da camme scanalate (che, contrariamente, sono molto rigide) e/o da camme elettriche (motori Brushless). Il secondo caso invece avviene ogni volta che viene a mancare la corrente elettrica in maniera accidentale (ad esempio a causa di un black-out). La mancanza di energia elettrica impedisce al computer a bordo macchina di continuare a monitorare e controllare il funzionamento dei vari assi elettronici della macchina, che sono comandati da motori brushless, che quindi continuano per inerzia il loro moto fino a fermarsi. Siccome ogni gruppo ha un’inerzia e una velocità/accelerazione istantanea diversa e variabile in funzione della posizione assunta all’interno del proprio ciclo nel momento della mancanza di corrente elettrica, i tempi di arresto risultano differenti, e questo causa la perdita di fase. I gruppi riempimento polvere/cronoidi e spingitori fondelli presentano interferenza meccanica col gruppo piattello per una certa durata del suo ciclo; in questa fase gli elementi entrano nelle boccole porta fondelli delle slitte mobili del piattello. È l’unico caso in tutta la macchina in cui parti meccaniche di gruppi diversi, vanno a “intersecare” i propri spostamenti. La progettazione di macchine che presentano interferenze di questo genere è generalmente sconsigliabile poiché si potrebbe presentare il rischio di uno scontro nel caso avvenga una perdita di fase tra i gruppi. Si sono cercate diverse soluzioni mirate a evitare un urto, derivato dall’interferenza meccanica, in caso di black-out oppure di ridurre il più possibile i danni che questa casualità può portare alla macchina. Il gruppo piattello è definito master rispetto a tutti gli altri gruppi; ha un’inerzia molto piccola e questo fa si che, in caso di black-out, il suo arresto avvenga praticamente istantaneamente, al contrario di ciò che avviene per tutti gli altri gruppi slave dotati di inerzia maggiore. Siccome l’arresto del piattello è istantaneo, il pericolo per tastatori e punzoni sollevatori di urto può avvenire solamente per compenetrazione: se gli elementi sono già all’interno della boccola, e restando fermo il piattello, l’inerzia del gruppo che fa proseguire il moto per alcuni istanti non farebbe altro che portarli fuori dalla boccola, non provocando alcun danno. Non vi è perciò il pericolo di “taglio” di questi elementi da parte del piattello. Perciò l’unica possibilità è che il black-out avvenga in un istante del ciclo dove gli elementi si stanno muovendo per entrare nelle boccole mentre anche il piattello è in rotazione.

Trasporto di materia in membrane polimeriche e nanocomposite per la separazione di gas

Membrane-based separation processes are acquiring, in the last years, an increasing importance because of their intrinsic energetic and environmental sustainability: some types of polymeric materials, showing adequate perm-selectivity features, appear rather suitable for these applications, because of their relatively low cost and easy processability. In this work have been studied two different types of polymeric membranes, in view of possible applications to the gas separation processes, i.e. Mixed Matrix Membranes (MMMs) and high free volume glassy polymers. Since the early 90’s, it has been understood that the performances of polymeric materials in the field of gas separations show an upper bound in terms of permeability and selectivity: in particular, an increase of permeability is often accompanied by a decrease of selectivity and vice-versa, while several inorganic materials, like zeolites or silica derivates, can overcome this limitation. As a consequence, it has been developed the idea of dispersing inorganic particles in polymeric matrices, in order to obtain membranes with improved perm-selectivity features. In particular, dispersing fumed silica nanoparticles in high free volume glassy polymers improves in all the cases gases and vapours permeability, while the selectivity may either increase or decrease, depending upon material and gas mixture: that effect is due to the capacity of nanoparticles to disrupt the local chain packing, increasing the dimensions of excess free volume elements trapped in the polymer matrix. In this work different kinds of MMMs were fabricated using amorphous Teflon® AF or PTMSP and fumed silica: in all the cases, a considerable increase of solubility, diffusivity and permeability of gases and vapours (n-alkanes, CO2, methanol) was observed, while the selectivity shows a non-monotonous trend with filler fraction. Moreover, the classical models for composites are not able to capture the increase of transport properties due to the silica addition, so it has been necessary to develop and validate an appropriate thermodynamic model that allows to predict correctly the mass transport features of MMMs. In this work, another material, called poly-trimethylsilyl-norbornene (PTMSN) was examined: it is a new generation high free volume glassy polymer that, like PTMSP, shows unusual high permeability and selectivity levels to the more condensable vapours. These two polymer differ each other because PTMSN shows a more pronounced chemical stability, due to its structure double-bond free. For this polymer, a set of Lattice Fluid parameters was estimated, making possible a comparison between experimental and theoretical solubility isotherms for hydrocarbons and alcoholic vapours: the successfully modelling task, based on application of NELF model, offers a reliable alternative to direct sorption measurement, which is extremely time-consuming due to the relevant relaxation phenomena showed by each sorption step. For this material also dilation experiments were performed, in order to quantify its dimensional stability in presence of large size, swelling vapours.

Survey on the spirilar flora of Lagomorphs

Members of the genera Campylobacter and Helicobacter have been in the spotlight in recent decades because of their status as animals and/or humans pathogens, both confirmed and emerging, and because of their association with food-borne and zoonotic diseases. First observations of spiral shaped bacteria or Campylobacter-like organisms (CLO) date back to the end of the 19th century, however the lack of adequate isolation methods hampered further research. With the introduction of methods such as selective media and a filtration procedure during the 1970s led to a renewed interest in Campylobacter, especially as this enabled elucidation of their role in human hosts. On the other hand the classification and identification of these bacteria was troublesome, mainly because of the biochemical inertness and fastidious growth requirements. In 1991, the taxonomy of Campylobacter and related organisms was thoroughly revised, since this revision several new Campylobacter and Helicobacter species have been described. Moreover, thanks to the introduction of a polyphasic taxonomic practice, the classification of these novel species is well-founded. Indeed, a polyphasic approach was here followed for characterizing eight isolates obtained from rabbits epidemiologically not correlated and as a result a new Campylobacter species was proposed: Campylobacter cuniculorum (Chapter 1). Furthermore, there is a paucity of data regarding the occurrence of spiral shaped enteric flora in leporids. In order to define the prevalence both of this new species and other CLO in leporids (chapter 2), a total of 85 whole intestinal tracts of rabbits reared in 32 farms and 29 capture hares, epidemiologically not correlated, were collected just after evisceration at the slaughterhouse or during necroscopy. Examination and isolation methods were varied in order to increase the sensibility level of detection, and 100% of rabbit farms resulted positive for C. cuniculorum in high concentrations. Moreover, in 3.53% of the total rabbits examined, a Helicobacter species was detected. Nevertheless, all hares resulted negative both for Campylobacter or Helicobacter species. High prevalence of C. cuniculorum were found in rabbits, and in order to understand if this new species could play a pathological role, a study on some virulence determinants of C. cuniculorum was conducted (Chapter 3). Although this new species were able to adhere and invade, exert cytolethal distending toxin-like effects although at a low titre, a cdtB was not detected. There was no clear relationship between source of isolation or disease manifestation and possession of statistically significantly levels of particular virulence-associated factors although, cell adhesion and invasion occurred. Furthermore, antibiotic susceptibility was studied (chapter 4) in Campylobacter and in Escherichia coli strains, isolated from rabbits. It was possible to find acquired resistance of C. cuniculorum to enrofloxacin, ciprofloxacin and erytromycin. C. coli isolate was susceptible to all antimicrobial tested and moreover it is considered as a wild-type strain. Moreover, E. coli was found at low caecal concentration in rabbits and 30 phenotypes of antibiotic resistance were founded as well as the high rate of resistances to at least one antibiotic (98.1%). The majority of resistances were found from strains belonging to intensive farming system. In conclusion, in the course of the present study a new species isolated from rabbits was described, C. cuniculorum, and its high prevalence was established. Nevertheless, in hare samples no Campylobacter and Helicobacter species were detected. Some virulence determinants were further analyzed, however further studied are needed to understand the potential pathogenicity of this new species. On the other hand, antimicrobial susceptibility was monitored both in C. cuniculorum and indicator bacteria and acquired resistance was observed towards some antibiotics, indicating a possible role of rabbitries in the diffusion of antibiotic resistance. Further studies are necessary to describe and evaluate the eventual zoonotic role of Campylobacter cuniculorum.

Hidden proxy per comunicazioni seamless da dispositivi multi-homed

Il concetto di mobilita' delle persone, assieme alla sempre maggior dipendenza di queste ai servizi offerti da Internet,ha fatto nascere la necessita' di rimanere connessi ad Internet indipendentemente dai propri spostamenti, mantenendo inalterate le prestazioni delle connessioni. HPforMSC, l'oggetto di questa tesi, e' un'architettura basata su hidden proxy che permette in maniera del tutto trasparente all'utente di utilizzare contemporaneamente le varie interfacce di rete a disposizione mantenendo inalterate le performance di tutte le comunicazioni in essere durante un handover, sia esso orizzontale o verticale.

OGRE: analisi di un motore grafico 3D

In questa tesi descriveremo e analizzeremo il motore grafico OGRE, acronimo di Object-Oriented Graphics Rendering Engine. La scelta di analizzare proprio questo motore grafico è legata a diverse considerazioni. Innanzitutto, OGRE è rilasciato con licenza open source e quindi rende disponibile il suo codice sorgente. Questo è molto importante, in un contesto di studio e sperimentazione come quello universitario, perché permette di comprendere e analizzare anche il funzionamento interno del motore grafico. Inoltre, OGRE è un progetto maturo e stabile con una vasta comunità di sviluppatori e utilizzatori alle spalle. Esiste molta documentazione a riguardo, tra wiki, libri e manuali, e un forum molto attivo per la richiesta di aiuto e consigli. A conferma, sia della bontà del progetto che delle ottime prestazioni del motore grafico, basta dire che OGRE è utilizzato anche da applicazioni commerciali, come videogame, editor 3D e simulatori. Infine, la caratteristica che contraddistingue OGRE da tutti gli altri motori grafici è il fatto di essere "solamente" un motore di rendering puro. Ciò significa che qualsiasi funzionalità non direttamente legata al rendering, come ad esempio la gestione degli input dell'utente, non è supportata da OGRE. Anche se questo può sembrare un difetto, in realtà ciò permetterà di concentrarci solamente sugli aspetti legati al rendering che, in un motore grafico, costituiscono la parte fondamentale.

Come città dell'infanzia. Architettura, educazione e immagine in due colonie per i figli degli Italiani all'estero a Cattolica e Tirrenia

The present doctoral dissertation deals with two significant case studies of Italian holiday camps which appear as interesting architectural experiences that reflect both the pedagogic and educational programmes of the fascist regime, and the discussion on the constructive and expressive principles that characterize the Italian architecture during the Thirties. The research explains the colony "XXVIII October for the sons of the Italian workers living abroad", today known as "Le Navi" ("The Ships"), built in Cattolica in 1934 and projected by the Roman architect Clemente Busiri Vici, and the feminine colony "for the sons of the Italian workers living abroad" built in 1934 in Tirrenia and projected by the architects Mario Paniconi and Giulio Pediconi. These holiday camps are the sole buildings commissioned directly by the Department in the Italian Foreign Office with the aim of offering a seaside stay to the sons of the Italians living in the colonies who, probably, could visit Italy only one time in their life. Firstly, the work illustrates the most relevant themes concerning these holiday camps, such as the representative intents that the buildings evoked to the children attending the places. Sun-bathing and group gymnastics were some of the rituals in the communal life, where order and discipline gave a precise internal organization to the spaces. Over the correspondence to practical functions, the figures and the forms of the different spaces of the buildings involve the children in an educational dimension. Subsequently, the function of the Department in the Italian Foreign Office and the planning and constructive ideas of the two colonies will be introduced. These colonies were conceived by a precise social project with educational, welfare and therapeutic aims. The elements, the spaces and the volumes create a fixed and theatrical scene of the life, full of ideological, political and celebratory overtones. Finally, the research shows that the relation between the architectural shape of the buildings and the rituals performed by fascist tutors produces an ideal space, extraneous to the external world that could influence the behavior of the children. The plan is to transmit to the children an image of Italy that will remain engraved in their minds once they have returned to their countries. In these projects there is the intent to transmit the image of "italianity" abroad. The way to do this was to plan for them a scenery which contains all the architectural elements of Italian cities. The holiday camps are proposed a sort of microcosm that appears as an "evocation" of the places and the spaces of Italian cities. The buildings appear as veritable "cities of childhood".