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Multifunctionality in epoxy/glass fibers composites with graphene interphase
No full textIn this project, the synergetic effect of a graphene interphase in epoxy/glass fibers composites was investigated by coating glass fibers (GF) with graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets by an electrophoretic deposition (EPD) technique. Graphite oxide was prepared using modified Hummers method in which raw graphite powder was oxidized using potassium permanganate (KMnO4) in acidic solution. Using ultrasonic technique, the graphite oxide was dispersed homogenously in water to create a stable GO suspension which was used as a bath in the EPD process. For the coating process, two copper plates were used as electrodes in the EPD process in which GF were placed in front of anode for GO deposition since GO tends to carry negative charges due to oxygen functional groups attached on the graphene structure as produced in the modified Hummers method. The deposition was carried out at different applied fields while maintaining the dispersion concentration and deposition time constant. This process produced GF coated with GO nanosheets, while to obtain GF coated with rGO, GO coated fibers were subjected to chemical reduction process where the fibers were placed in an environment of hydrazine hydrate which reduced the GO coating on GF. Through this step, rGO coated GF were obtained. The oxidation level of GO and rGO was evaluated using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron (XPS) spectroscopy techniques which confirmed the successful oxidation of graphite powder into graphite oxide due to liquid chemical oxidation process while the hydrazine reduction method reduced the oxygen amount from 34% to 10% in GO hence converting it into rGO. Scanning electron microscopy analysis of coated fibers revealed uniform coating of GF with GO and rGO where the amount of deposition increased with increased applied field.
The effect of GO or rGO coating on GF obtained by EPD process was first evaluated by determining the adhesion between GF and epoxy matrix. Single fiber fragmentation test was utilized to determine the interfacial shear strength (ISS) between the uncoated or coated fibers and epoxy matrix. Single fiber epoxy composites were prepared by using GO and rGO coated fibers and were tested using a mini-tensile testing machine and monitoring the lengths of fragments of fibers obtained during the tensile test. It was observed that in case of GO coated fibers, the ISS increased by 218% in comparison to uncoated fiber based composite. The increase of interfacial adhesion in this case, it can be attributed to the fact that GO carries oxygen functional groups which creates physical and chemical bonding between both the GF surface and the epoxy matrix. For investigating the interactions between GF and GO, atomic force microscopy (AFM) was used to determine the interfacial adhesion between them by scratching GO on GF. It was proved that the delamination strength was higher than the ISS, hence proving the efficacy of the selected GO deposition method. On the other hand, single fiber fragmentation tests indicated a 70% increase in ISS for rGO coated GF when embedded in the epoxy matrix as compared to uncoated fibers. This increment is lower than that observed for GO coated fibers and it has been attributed to the fact that rGO does not possess enough oxygen based functional groups to efficiently interact with the polymer matrix. The observed increase in ISS with respect to uncoated GF is based on the frictional forces offered by the roughness of rGO nanosheets. This confirms that the presence of an interphase (either GO or rGO) creates favorable load transfer mechanism through either chemical or physical bonding or even both depending on the nature of the interphase. To test further the positive effect of GO based interphase in epoxy/glass composites in terms of mechanical reinforcement, multifiber (uncoated and GO or rGO coated) reinforced epoxy composites were created by hand lay-up method. Laminas of fibers were wetted by epoxy resin and stacked over one another in certain number depending on the thickness of the resultant composite. These composites were subjected to various mechanical tests, such as flexural tests, short-beam shear tests, mode I interlaminar fracture toughness and creep tests which also confirmed that GO and rGO based interphase in epoxy/glass composites increase the performances of the composite with respect to that of the uncoated GF based composites. GO proved to be the best interphase in terms of mechanical properties obtained, as proved before. The multifunctionality of such interphases based on graphene was analyzed and confirmed using multiple tests on epoxy/glass composites containing uncoated and coated (GO or rGO). In particular, the electrical and thermal conductivity of the composites were tested in which the composites based on rGO interphase showed the highest conductivity which not only confirms that rGO coated fibers in epoxy/glass composites render the composites conductive but also proves the successful chemical reduction process used in this work.
These conductive composites were subjected to piezoresistivity tests in which the applied longitudinal strain in different modes resulted in change in resistance thus showing a possibility of using such composites as strain sensing devices or for structural health monitoring purposes in automotive or aerospace applications.
These conductive composite specimens were also analyzed for their dielectric properties. The tests showed increased permittivity values as compared to both uncoated and GO coated composites thus revealing the possibility to use composites containing rGO coated fibers for electromagnetic interference shielding applications
Cioran e l'Utopia. Prospettive del grottesco
No full textQuesta tesi nasce come un tentativo teoretico di rispondere a una provocazione di Cioran, per il quale «l’utopia è il grottesco in rosa». In questa sentenza, l’utopia viene definita attraverso un ossimoro che ne evidenzia gli aspetti ridicoli, come se Cioran stesse semplicemente proponendo una parodia del pensiero utopico. Scopo della tesi è mostrare il carattere dialettico di questa parodia, attraverso la quale viene diagnosticata una delle ambivalenze costitutive della coscienza utopica: la tensione antropologica verso l’idea di un bene futuro e ipotetico, a dispetto di un presente contrassegnato dalle stimmate del male. Al riguardo l’utopia risulta essere una caricatura doppiamente paradossale della storia umana perché il suo aspetto grottesco, e dunque ridicolmente mostruoso, è determinato non da un’eccessiva presenza del male, ma da una claustrofobica onnipresenza del bene. Nella letteratura critica degli ultimi anni, la posizione anti-utopica di Cioran è stata giustamente collegata sia alla sua postura scettica che al suo stile paradossale, uno stile capace di smascherare tanto le illusioni metafisiche quanto le contraffazioni ideologiche. Da questa prospettiva il «grottesco» è stato spesso considerato come un aggettivo, che connota esteticamente le paradossali conclusioni a cui giunge Cioran rispetto alla storia; tuttavia, non è stato quasi mai considerato in quanto concetto, capace di orientare teoreticamente i presupposti del pensiero cioraniano. Per questa ragione, nella parte introduttiva della tesi, propongo una dettagliata analisi storica del concetto di grottesco, per mostrare successivamente i rapporti che il simbolismo del grottesco instaura, da un lato, con l’arte ornamentale delle grottesche rinascimentali, dall’altro, con l’immaginario utopico del mondo alla rovescia. I punti di riferimento dell’indagine saranno gli studi novecenteschi di Wolfgang Kayser, Michail Bachtin e Geoffrey Harpham. Questi autori, in modi diversi, hanno mostrato che il grottesco, per quanto sia una categoria concettualmente ambivalente, attiene a tre particolari ambiti della discussione filosofica: a) l’antropologia, nella misura in cui i corpi fantasiosi e anatomicamente impossibili del bestiario grottesco impongo una riconfigurazione del rapporto tra uomo e animale e del rapporto tra mito e storia; b) l’arte, nella misura in cui questa riconfigurazione implica un capovolgimento gerarchico delle relazioni tra forma e contenuto, centro e margini, armonia e disarmonia; c) la poesia, nella misura in cui le «trasfigurazioni» (talvolta fantasiose, talvolta demoniache) delle figure grottesche e delle decorazioni arabesche hanno rappresentato, soprattutto per il Romanticismo ottocentesco, un rapporto tragico e drammatico con la sfera del «sublime». Tutti questi ambiti si relazionano, a loro volta, con il simbolo utopico-carnevalesco della maschera grottesca, che svolge la funzione di sovvertire simbolicamente e comicamente una realtà che deve cambiare, perché troppo contraddittoria e irrazionale per permanere nello stato attuale. Per Cioran, viceversa, la realtà può cambiare solo verso il peggio, ragion per cui egli rinnega le elucubrazioni utopiche di un mondo perfettibile. Ma la sua condanna non è univoca e, soprattutto, non si traduce in un’accettazione passiva della condizione presente: egli rifiuta questo mondo, proprio perché questo mondo è troppo assurdo e deforme per essere accettabile. La sua critica all’utopia, dunque, è una posizione molto complessa, nella quale sono rintracciabili i diversi elementi del simbolismo grottesco che abbiamo precedentemente elencato. Nelle sue opere Cioran tratteggia una feroce «anatomia» della storia umana, che si converte spesso in una disillusa e malinconica «nostalgia dell’altrove», come se l’utopia si traducesse non tanto in una «speranza» rivolta al futuro, quanto in un «rimpianto» di ciò che l’uomo avrebbe potuto essere. In questo frangente, il grottesco offre una chiave di lettura originale per interpretare l’evoluzione del pensiero cioraniano dal periodo giovanile rumeno a quello francese della maturità. In un confronto serrato con i testi si mette in risalto che il giovane Cioran, di fronte al grottesco della storia – lucidamente diagnosticato già in diversi articoli degli anni Trenta – reagisce «romanticamente», affidandosi all’ideale sublime, tragico e folle della trasfigurazione. Arrivato a Parigi, e in seguito al fallimento di quella trasfigurazione, egli mette in scena una sorta di «parodia» metafisica delle sue illusioni romantiche, arrivando a celebrare, nel Précis de décomposition, «l’orrore testicolare del ridicolo di essere uomini». Questo terrore si proietterà nelle sue confutazioni dell’utopia, che egli definisce come il tentativo tragicomico «di rifare l’Eden con i mezzi della caduta, per permettere così al nuovo Adamo di conoscere i vantaggi dell’antico». Tutta questa serie di ossimori, attraverso cui Cioran delimita l’orizzonte delle utopie, sono pienamente comprensibili soltanto se inseriti nel contesto simbolico del grottesco. È ciò che è stato fatto nei quattro capitoli della tesi, grazie a uno studio minuzioso di alcune metafore del grottesco che si presentano ripetutamente nei testi cioraniani e che sono strettamente connesse al discorso utopico: la caverna, il troglodita, la prigione trasparente, il corpo squartato, il cannibale, il licantropo, l’ombra, il buffone.
Nel primo capitolo ci si focalizza sulle declinazioni antropologiche della metafora della caverna e del troglodita, immagini che si richiamano sia alla condizione “paradisiaca” dell’uomo primitivo, che viveva in unisono con la natura, sia al fallimento “apocalittico” dell’uomo civile, che procede verso la catastrofe. Cioran, rielaborando in modo originale alcune riflessioni sulla città e sul riso di Simmel e di Bergson, definisce l’uomo come un «architetto delle caverne», che subisce, nel perimento moderno di una metropoli, lo stesso sentimento di angoscia esistenziale e claustrofobica che i suoi antenati dovevano aver provato nelle preistoriche spelonche. In un secondo momento, l’analisi si sposta sul versante mitologico, poiché la caverna non è soltanto la dimora del troglodita, ma anche la prigione di Saturno. E Saturno, oltre ad essere il dio del carnevale, è anche il pianeta sotto il cui segno nascono i malinconici. Attraverso un confronto con Marsilio Ficino, che aveva fatto di Saturno il patrono della sapienza filosofica, si mostra in che modo il culto dei Romantici per il genio malinconico sia erede della tradizione metafisica rinascimentale. Questo è importante per due motivi: in primo luogo perché l’Utopia di More (come si dimostra nel secondo capitolo) ripropone in chiave narrativa una speranza filosofica di matrice «saturnina»; in secondo luogo perché Cioran parla spesso di sé come di un pensatore malinconico, profondamento influenzato dalla poesia e dalla filosofia romantica. In virtù di questo, nella parte finale del capitolo si accenna un confronto con tre pensatori romantici che hanno discusso, in modo decisivo, della malinconia, del sublime e del grottesco: Friedrich Schlegel, Victor Hugo, Théophile Gautier.
Nel secondo capitolo ci si dedica, per l’appunto, al tema dell’utopia, attraverso un confronto con tre autori che sono fondamentali per comprendere l’anti-utopismo di Cioran: Thomas More, Michel de Montaigne e Jonathan Swift. Dei tre, More è senz’altro quello più distante dalle posizioni di Cioran, ma la sua Utopia, se letta da una prospettiva ontologica, rivela come siano instabili i confini tra la finzione e la realtà, tra il presente e il futuro: più precisamente, mostra che le aspettative nei confronti del futuro dipendono dalle deformazioni prospettiche del presente. Tema ripreso, in chiave grottesca e parodistica, nei Viaggi di Gulliver, in cui la contrapposizione prospettica tra i microscopici lillipuziani e i giganteschi corpi degli abitanti di Brobdignac rivela, in controluce, la miseria dell’uomo: un animale razionale incapace di accettare le proprie reali dimensioni e ridicolmente incline a credersi più grande di quel che è. Cioran si riconosce esplicitamente in questa denuncia misantropica e considera Swift «l’autore che h[a] ammirato di più». Nella bibliografia critica di Cioran, però, sono pochi i riferimenti a Swift. Si è cercato di rispondere a questa lacuna per evidenziare un aspetto che non era stato ancora notato: il carattere «fisiologico» del pensiero cioraniano non è soltanto erede della «metafisica organicistica» di Nietzsche e Schopenhauer, ma ha anche evidenti affinità con il grottesco corporeo swiftiano. A tal proposito, inoltre, ci siamo soffermati sullo scetticismo di Montaigne, che, negli Essais, fa del suo corpo il punto di convergenza dei propri dubbi verso la realtà circostante. In particolare, abbiamo esaminato il saggio Dei cannibali, in considerazione del fatto che Cioran riprenderà, in modo distopico, il tema dell’antropofagia.
Nel terzo capitolo, abbiamo confrontato da un punto di vista paradigmatico la Repubblica platonica con la critica all’utopia di Cioran: se Platone aveva elaborato la sua kallipolis per indicare il modello teorico a cui attenersi per realizzare la giustizia sociale, Cioran nega “antiplatonicamente” la possibilità stessa di ottemperare al bene, come se si stesse chiedendo: Visto che ci si muove solo per fare il male, perché non si dovrebbe fare nulla? Per rispondere a questa interrogativo, cercheremo di mostrare il carattere paradossalmente “normativo” del cioraniano invito al distacco e alla rinuncia di qualsiasi tipo di azione. Il confronto tra i due autori partirà da un’attenta analisi, da un punto di vista antropologico, del mito della caverna platonica, per vedere in che senso la condizione dei prigionieri del VII libro della Repubblica si possa relazionare allo scetticismo e alla tragica «passione del reale» di Cioran. In seguito, ci focalizzeremo sul ritratto del tiranno di Platone per confrontarlo con quello proposto da Cioran nel saggio À l’école des tyrans. Per fare questo dovremmo anche misurarci con il personaggio “platonico” di Trasimaco e con quello “cioraniano” di De Maistre, nel tentativo di approfondire il rapporto che Cioran instaura tra regime rivoluzionario e pensiero reazionario, tra ideologia e utopia: o la vanità di tutte le riforme.
Questo problema viene ripreso nel quarto capitolo grazie a un parallelismo tra Cioran e Salomone, tra il pensatore marginale che aspirava alla saggezza di un clochard e il saggio sovrano dell’antichità che aveva proclamato la vanità di tutte le cose. L’assoluta e disarmante lucidità delle visioni di Salomone evocano le «rivelazioni della morte» di Lev Šestov e «l’esperienza dell’abisso» di Benjamin Fondane, altri due pensatori decisivi nella formazione di Cioran, il quale, similmente a loro, era «continuamente in lotta contro la tirannia e la nullità delle evidenze». E proprio richiamandoci a Fondane, nella parte conclusiva del lavoro ci concentriamo su Baudelaire, che, nel saggio su Quelques caricaturistes français, ha qualificato il grottesco come una forma di «creazione», come un tipo di «comico assoluto» che tanto più si avvicina al sublime quanto più si confonde con una sensazione di vertigine. Riscontriamo lo stesso genere di smarrimento nell’opera di Cioran, che diceva di essersi aggirato «con molte precauzioni, […] nei paraggi delle profondità, per spillar loro qualche vertigine e poi svignarsela, come uno scroccone dell’abisso».
Cioran, nella sua disarmante analisi della storia e dell’uomo, è stato anche uno scroccone dell’utopia e – agli antipodi da ogni visione statica e immutabile della realtà – non ha fatto altro che porsi in modo paradossale e umoristico la più seria e la più platonica delle domande: che cosa non dobbiamo fare per non peggiorare ulteriormente il mondo. Questa caverna della sofferenza umana
Weak Lyapunov functions for hybrid dynamical systems: applications to electrical and mechanical systems
Get PDFIn this work we propose a number of relevant engineering applications that exhibit both a continuous and a discrete evolution, and are therefore suitably described by a recent formalism for hybrid dynamical systems. More specifically, (i) we design observer schemes for a nonsmooth disturbance arising in AC/DC conversion, which we then cancel from a desirable signal; (ii) we show how reset actuation applied to nonlinear mechanical systems can at the same time sustain or damp oscillations; (iii) we study the feedback interconnection of a classical proportional-integral-derivative controller with a sliding mass under Coulomb friction through differential inclusions. In the context of dynamical systems, we analyze the properties of these applications in terms of asymptotic stability through Lyapunov functions tailored for hybrid systems. Instead of the standard Lyapunov conditions, we prove asymptotic stability through weaker, or relaxed, conditions that are compensated by additional (structural) properties that may be easier to verify
Empirical Studies on the European Economic Integration. An Approach Based on Sraffian Schemes and Subsystems.
Get PDFIn this thesis the specialization patterns of a group of countries are studied in order to check whether they are compatible with Comparative Advantages or whether there is scope to diminish CO2 emissions through alternative specialization patterns.
The main focus is on European countries. A set of Input-Output Tables during the period 1995-2011 is used to perform the analysis, which is based on the Sraffian notion of subsystems.
The results suggest that Comparative Advantages did not work well in Europe during the period considered. Alternative specialization patterns may allow to exploit better Comparative Advantages and, moreover, to decrease the CO2 emissions related to economic activities
Nancy Huston in Self-translation. An Aesthetics of Redoublement.
Get PDFSelf-translation is a fairly recent branch of studies. Despite its existence as a literary and linguistic phenomenon was proved to date back to ancient times, its practice in the globalized Twentieth Century has lately led scholars (concurrently with the cultural turn in translation studies) to delimit and deepen a field of enquiry that is transdisciplinary in nature, its focus being on multilingual writers who translate their literary works themselves.
The phenomenology of self-translation depends on a variety of factors: the type of bilingualism of writers; the geo-political and social standing of the languages involved in their production; the literary traditions they combine; the scopes and consequent strategies for self-translation, etc. As a worldwide phenomenon, thus, self-translation is far from being satisfyingly mapped. For this reason, exhaustively investigated case studies are still needed as a preliminary step for further research leading to universal considerations. Nancy Huston is a prolific bilingual author of both fiction and non-fiction writing, born in Anglophone Canada but living in France since the early Seventies. While secondary bibliography exploring single couples of her self-translated texts presently covers a good deal of her novels, a comparative analysis of the evolution of this practice on a vast span of time was still missing. The aim of the present thesis is precisely to provide such analysis on a selection of Huston’s novels from Plainsong / Cantique des plaines (1993) to Danse noire (2013)/ Black Dance (2014).
The thesis is subdivided in two main parts, each of three chapters. Chapter I provides an heuristic overview of self-translation, reporting the most influential bibliographical material that has focused, in turn, on: the theoretical debate ignited by self-translation around the dichotomic relation between ‘originals’ and ‘translations’; the existing typologies of self-translated text; the history of this practice over the centuries; its sociolinguistic assumptions and aftermaths; a short overview of scholars that discourage the thinking of self-translation as a category with its own autonomous epistemology. The last section of the chapter, instead, is devoted to presenting the theoretical and methodological devices that enabled a comparative reading of Huston’s self-translated versions. Jan Hokenson and Marcella Munson’s focus on self-translated versions as a single bilingual text, Marilyn Gaddis Rose’s stereoscopic reading, Anton Fedorov’s functional equivalence and the self-translation categories of Michaël Oustinoff set the basis to analyse Huston’s self-translations (published as autonomous texts) as ‘twin texts’ alongside a chronological axis of development of her aesthetics.
Being often described by its performers as a physically and psychologically fatiguing enterprise, self-translation is usually engendered by profound intimate motivations. For this reason, Chapter II is devoted to investigate those motivations in Nancy Huston’s biography. As it is typical of the post-modern, hyper-self-aware writer, Huston has imbued her fiction and non-fiction writing with self-portrayals recounting her childhood in Calgary (e.g., Nord perdu (1999)/Losing North; Longings and Belongings. Toronto: McArthur and Co., 2005); her adolescence in the U.S.A, and the life-changing decision to move to Paris for a Junior Year abroad that actually never came to an end. Tutored by Roland Barthes at the École de Hautes Etudes en Sciences Sociales, Huston became a writer in the French language: first as an essayist for feminist reviews, then, after publishing her thesis (Dire et interdire, éléments de jurologie; Paris: Payot, 1980) and after her marriage with Tzvetan Todorov in 1980, by launching into fictional writer with a debut novel Les Variations Goldberg, that Gérard Genette defines a “petit chef d'oeuvre.”
For the following ten years, Huston carries on publishing in French two novels (Histoire d’Omaya. Paris: Seuil, 1985 and Trois fois septembre. Paris: Seuil, 1989), as well as intimist correspondence and essay: Lettres parisiennes. Autopsie de l’exil (Paris: J’ai lu, 1987) and Journal de la création. (Paris: Seuil, 1990). Especially in these latter works, reflections on her ‘voluntary exile’, ‘false bilingualism’ and the revolutionary discovery of motherhood abound. Together with a neurological illness and a psychological crisis in 1986/87, experiencing motherhood and facing the choice of which mother-language to teach to her own daughter, urged Huston to analyse her choice to hibernate into the French language and culture, reaching the conclusion that – although up to a point this language had endowed her with freedom and inspiration – she should nonetheless make an effort to repair the break with her native tongue. English was connected to a traumatic childhood experience: when Nancy was six her parents split up and her mother left the family. Chapter III analyses in-depth the unfolding of Huston’s reasoning on her two languages and the different place they occupy in her mind and in her writing, focusing especially on the first novel she wrote in English (Plainsong) which is incidentally also the first she chose to self-translate and the first one where Canada is recognized as a constitutional element of her identity as a writer. Expatriation and bilingualism ineluctably call for a question and redefinition of a personal sense of identity. Rather than being restricted into non-fictional writing, these phenomena are transformed into literary themes and become an essential features of her novels (in the form of varying motifs).
Concurrently, the act of self-translation becomes a compulsory step in her literary aesthetics: « Il y a deux versions de tous mes romans […] pour moi c’est important qu’il ne manque pas une page ou un paragraphe et que l’éditeur américain approuve ce que l’éditeur français approuve et inversement. Je tiens à ce que les deux versions soient identiques dans la mesure du possible. » The purpose of the Second Part of the thesis is essentially to test this declaration of translating poetics. After having preliminarily compared all the couples of self-translated works, four text where selected that varied significantly for their linguistic genesis and the way in which they were self-translated – but shared the thematic explorations fuelled by Huston’s own bilingual and expatriate standpoint.
Hence, Chapter IV illustrates a comparative reading of the novels L’empreinte de l’ange (Arles: Actes Sud, 1998) – first written entirely in French and subsequently self-translated into English as The Mark of the Angel (London: Vintage, 2000). This ‘doxal’ translation exemplifies Huston’s research for equivalence: a balanced care to maintain the prosodic rhythm, the wordplays, the images of the first version whenever possible, and to compensate for those elements that are inevitably lost due to the intrinsic features of each language.
In Chapter V, two differently bilingual works are analysed that show how self-translation can be exploited as a creative literary device. The first draft of what later became Instruments of Darkness (Toronto: Little, Brown and Co., 1997) and Instruments des ténèbres (Arles: Actes Sud: 1996) was written alternating chapters in English with an equivalent number of chapters in French. Limbes/Limbo. Un hommage à Samuel Beckett (Arles: Actes Sud, 2000), instead, is a side-by-side edition of two monolingual texts resulting from a bilingual pastiche inspired to Beckett’s writing style and literary poetics. The mutual influence of the two linguistic systems is evident on different textual levels: the prosodic rhythm and the diffused isomorphisms bear witness of an aesthetics of translation aimed at privileging the phonetic body of the text.
Chapter VI takes into consideration one the latest twin novels by Huston, Black dance and Danse noire. Symmetrically to the first novel, the first draft was the English one (since part of the novel is set in Montreal); however, a great deal of dialogues were written in Quebec French. The double self-translation resulted in very asymmetrical products. While the Standard English text published in the U.S.A displays only few scattered interferences of the French language, the version whose narrative language is Standard French depicts a richly multilingual panorama, with interjections in German, Portuguese, Quebec French, and local varieties of English.
The conclusive remarks are tripartite, focusing in turn on the texts, on the author, and on the wider picture of self-translation in global literature. From a thematic perspective, the novels share an extensive use of polyphony, the constant presence of music, multicultural sets of characters. From a translational perspective, the most evident feature is a constant attention to “phonetical rubbings and rhymings” of each language and for creating equivalent musical patterns in translation. Comparison showed, though, that strategies of self-translation are negotiated from context to context and from text to text, even within the corpus of a single author. As regards the author, self-translation can be read as an aesthetic device for healing the author’s linguistically and culturally fragmented identity: the literary corpus in fact physically redoubles (either from French to English or from English to French), thus fulfilling the fantasy of the other self in the paper, if not in the flesh. In the framework of current research on global literature, eventually, self-translation posits as a practice that overcomes national boundaries and is part of a larger ethical calling
Processes in the formation of publics: A design case study on dyslexia
No full textThe work presented in this thesis is aligned with a renewed interest in design for opening new possibilities for democracy. This thesis builds on a growing corpus of research investigating the role of design in supporting the formation of publics. In this thesis, the concept of publics is aligned with Dewey’s view, which refers to heterogeneous groups of people concerned about an issue who organize themselves to address it. This thesis aims to contribute to this corpus of research by investigating the following research questions: what design processes can contribute to the formation of publics? and what design interventions can enable these processes? Answers to these questions are constructed by engaging in a practice-based design
research of a case study of dyslexia in Trentino, a region in Italy where dyslexia is a controversial issue grounded not only in medical but also societal and political conditions. The main contribution of the thesis is a method to support the formation of publics following a practice-based interaction design approach. This method proposes articulating, representing and reconfiguring as three intertwining and complementing processes that can support the formation of publics. In addition, it proposes
that designing interventions on the basis of physical artefacts, digital platforms and events can enable people to act on an issue. Finally, it proposes programs for action as takeaways of design research projects that aim to enable people to act on societal issues
Novel PM Tool Steel with improved hardness and toughness
No full textUltrafine grained (~ 1μm) steels have been the subject of extensive research work during the past years. These steels generally offer interesting perspectives looking for improved mechanical properties. UFG Powder Metallurgy hot work tool steels (HWTS) can be fabricated by high energy mechanical milling (MM) followed by spark plasma sintering (SPS). However, similarly to most UFG and Nano-Crystalline (NC) metals, reduced ductility and toughness result from the early plastic instabilities in these steels. Industrialization of UFG PM Tool Steels requires the application of specific metallurgical tailoring to produce tools with sound mechanical properties or in a more optimistic way, to break the Strength-Toughness “trade-off” in these materials. Among the possible ways proposed to restore ductility and toughness without losing the high strength, “Harmonic microstructure” design seems to be a very promising endeavor in this regard. Harmonic microstructure materials consist of a tunable volume fraction of evenly spaced “isolated” coarse-grained particles (CG) surrounded by a 3D interconnected network of UFG particles. CGs provide ductility and toughness, while high strength is guaranteed by the interconnected network of UFGs. This peculiar design offers an extra work hardening due to the generation of geometrically necessary dislocations at the interfaces of UFGs and confined CGs that are essentially present to accommodate the strain gradient imposed by the inhomogeneous (bimodal grained) microstructure.
The first part of this work is devoted to the development of PM tool steels with harmonic microstructure. Due to the difficulties of processing hard tool steel particles according to the methods reported in the literature, an economical, simple alternative approach is also proposed. Near full density “Harmonic structure“ AISI H13 samples were produced using different volume fractions of UFG/NC mechanically milled (MM) and CG as-atomized particles followed by short time (30 min) low-temperature (1100°C) SPS. A combination of high hardness and significantly improved fracture toughness was achieved for the blends containing more that 50% UFG particles. The optimized mechanical properties was achieved by the mixture of 60% UFG particles where the sample showed a hardness near to the value predicted by the rule of mixtures (i.e. 405 HV10 vs. 406 HV10) while apparent fracture toughness (Kapp) was about 10% higher than that of predicted by the same rule (i.e. 52.0 MPa*m1/2 vs. ~47.0 MPa*m1/2). A toughening effect was evidenced for the samples essentially showing harmonic microstructure. Toughening was interpreted to be the result of the deviatory effect of coarse-grained round atomized particles together with energy dissipation by decohesion at the CG/UFG or UFG/UFG interfaces leading to a local drop of the driving force for the crack propagation. The design allowed to easily adjust the strength and toughness to meet the specific application-oriented requirements. The harmonic steel was also subjected to Thermal Fatigue (TF) testing. The preliminary results confirmed that this microstructure combined the beneficial effects of both of its constituents, i.e., the low crack nucleation rate of CG H13 and the low crack propagation rate of UFG H13, thus showing the lowest pyrocracking factor. Moreover, TF crack deflection as an extrinsic toughening mechanism was evidenced in Harmonic Microstructure.
The second part of this work deals with the production and characterization of a PM HWTS reinforced with partially stabilized zirconia (PSZ). HWTS composites show improved hardness and remarkable wear resistance but generally also a systematic lower fracture toughness than the base material. Deteriorated toughness in metal matrix composites (MMCs) with a high strength matrix is mainly interpreted as a result of early damage initiation at the hard particles (HPs) or Matrix-HP interface. This damage can be even anticipated in the presence of readily damaged HPs (i.e. processing related flaws). Selection of PSZ as reinforcement was aimed at improving the strength and fracture toughness of the composite by taking advantage of the transformation toughening effect of PSZ. Two different types of PSZ, different volume fractions (10 and 20 vol. %) and sizes of reinforcement were used. Mechanical Alloying (MA) was used to process the composite powders to refine the matrix microstructure and both the matrix and PSZ particle size hence increasing the strength of the PSZ particles according to the Griffith strength formalism, and also to overcome the aggregation problems. Powders were consolidated by (SPS). The influence of processing parameters on density and microstructure was investigated. Short time (30 min) low-temperature (1100°C) consolidation by SPS allowed preserving the refined microstructure while achieving a maximum relative density of 98.6%. Moreover, short time sintering did not allow the extensive formation of thermodynamically plausible reaction products at the PSZ-H13 interface. As a result of dispersion hardening, the hardness of the as-sintered composites (i.e. maximum hardness of ~ 920 HV10) was increased compared to the mechanically milled UFG H13 (i.e. ~ 755 HV10), while in comparison to the as-atomized H13 (i.e. ~ 640 HV10) the improved hardness was ascribed to the synergic effect of dispersion hardening, microstructural refinement and strain hardening induced by MA. In these composites, tempering resistance at 550°C and 650°C was significantly improved due to the dispersion hardening effect. The hot compressive yield strength of the composites at 650°C and 450°C was increased up to 1.8 times the unreinforced UFG H13. t to m transformation during hot compression was evidenced and contributed to the strengthening. The hardness of the composites in heat treated condition (i.e. ~ 600 HV10) was significantly improved compared to that of the unreinforced matrix (i.e. ~ 420 HV10) while the apparent fracture toughness was drastically decreased to half the Kapp of the base material (19 MPa*m1/2 vs. 36 MPa*m1/2). However, the fracture toughness was slightly higher than that of a TiC reinforced H13 (i.e. 17 MPa*m1/2) with the same hardness (i.e. ~ 600 HV10)
Quantitative analyses to study tumor clones dynamics and tumor heterogeneity
No full textProstate cancer is a highly heterogeneous disease and its manifestations can vary from indolent localized tumor to widespread metastases. This heterogeneity is also observed at the molecular level both inter- and intra-patient. Intra-patient heterogeneity in the clinical setting of men with castration resistant prostate cancer (CRPC) might be informative in terms of treatment decision. Here I present analytical work on two approaches relevant to the characterization of intra-patient heterogeneity and applied to unpublished CRPC patients sequencing data. The first is based on the genome wide interrogation of multiple metastatic and primary tissue biopsies from single patients. I present genomic analyses to decipher the content of multiple tumor biopsies from CRPC patients and provide comparisons to highlight similarities and differences and to identify alternative patterns of aberrations. The second approach, alternative to tissue biopsies that might under-represent the genomic landscape of the patient’s disease, relies on liquid biopsies, a minimally invasive test that is also amenable to serial sampling. Liquid biopsies contain circulating cell free DNA (cfDNA) released from widespread tumor cells, potentially uncovering the full tumor landscape. By using next generation sequencing on cfDNA obtained from plasma, I developed strategies aimed at systematically tracking the reiterative process of genetic diversification leading to disease evolution and to detect genomic aberrations. I specifically focused on an ad hoc computational procedure (ABEMUS) to detect somatic point mutations that could emerge under treatment pressure and as drug resistance mechanism. The work I present is relevant to the context of precision oncology that exploits detailed patient-specific molecular information to diagnose and follow cancer progression with the ultimate goal of promptly guiding treatment decisions to improve clinical outcome with transdisciplinary strategies. The analytical work I developed can be applied to the study of any tumor type
Synthesis and Characterization of Nanostructured Materials for Hydrogen Storage Applications
No full textThe development of new materials represents the recent frontier in hydrogen storage technologies. In the last few decades the preparation of nanostructured materials has had an increasing interest, because the hydrogen storage capacity is closely linked to the material dimensions, and increases considerably with the reduction of the particles sizes. The chemical synthesis plays an important role in the development of new materials for hydrogen absorption because it allows a good control of the hydride phase sizing, and thus of the kinetics/ thermodynamics of such materials. The aim of the work concerns the synthesis by chemical techniques of metals nanoparticles. Nanostractured metals embedded into a polymeric matrix are prepared. The polymer was used for achieving nanoparticles with tailored properties
Mathematical models for host-parasitoid interactions and biological control of Drosophila suzukii
No full textThis thesis treats mathematical models for host-parasitoid interactions. It is composed of three parts. In the first part, a class of such models is analyzed theoretically. It focuses on the phenomena of multiple coexistence equilibria of competing parasitoid species. The second part is about a model for determining how a parasitoid release should be timed to optimally control the invasive fruit fly Drosophila suzukii. The third part analyzes an experiment for releasing parasitoids in a greenhouse which is infested by D.suzukii. The models presented are used to discuss how to improve such biological control strategies