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Modelling of driven free surface liquid filmsGalvagno, Mariano January 2015 (has links)
In several types of coating processes a solid substrate is removed at a controlled velocity U from a liquid bath. The shape of the liquid meniscus and the thickness of the coating layer depend on U. These dependencies have to be understood in detail for non-volatile liquids to control the deposition of such a liquid and to lay the basis for the control in more complicated cases (volatile pure liquid, solution with volatile solvent). We study the case of non-volatile liquids employing a precursor film model that describes partial wettability with a Derjaguin (or disjoining) pressure. In particular, we focus on the relation of the deposition of (i) an ultrathin precursor film at small velocities and (ii) a macroscopic film of thickness h ∝ U^(2/3) (corresponding to the classical Landau Levich film). Depending on the plate inclination, four regimes are found for the change from case (i) to (ii). The different regimes and the transitions between them are analysed employing numerical continuation of steady states and saddle-node bifurcations and simulations in time. We discuss the relation of our results to results obtained with a slip model. In connection with evaporative processes, we will study the pinning of a droplet due to a sharp corner. The approach employs an evolution equation for the height profile of an evaporating thin film (small contact angle droplet) on a substrate with a rounded edge, and enables one to predict the dependence of the apparent contact angle on the position of the contact line. The calculations confirm experimental observations, namely that there exists a dynamically produced critical angle for depinning that increases with the evaporation rate. This suggests that one may introduce a simple modification of the Gibbs criterion for pinning that accounts for the non-equilibrium effect of evaporation.
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Progettazione e sperimentazione di un intervento di Accoglienza Anticipata e Integrata in Università Cattolica / Planning and Experimentation of a Participation of Acceptance Anticipated and Integrated in Università CattolicaBONELLI, EMANUELA 09 March 2007 (has links)
La ricerca presentata si inserisce nell'ambito dell'orientamento universitario quale studio di nuove metodologie in tema di orientamento richieste dalla riforma universitaria (a partire dalla Legge delega 127 del 1997). Con il nuovo sistema universitario, l'orientamento acquista un rilievo di primo piano, infatti, il D.M. 509/99, in attuazione alla delega (Legge 127/97), include l'orientamento tra le attività formative che devono essere obbligatoriamente previste nei regolamenti didattici d'ateneo. Il suddetto scenario ha motivato la presente ricerca tale da prevedere all'interno dell'Università Cattolica del Sacro Cuore di Milano un intervento di accoglienza orientativa anticipata ed integrata che si inserisce nelle attività insite nei Progetti ponte con l'obiettivo di sostenere le nuove matricole alla presa di decisione orientativa, per accogliere adeguatamente gli studenti in università e favorirne l'inserimento nel nuovo contesto di studi. Si tratta, pertanto, di una ricerca applicata con la finalità di valutare il servizio di accoglienza erogato. Questa riflessione su nuove metodologie di azione orientativa ha delineato nuove collaborazioni del CROSS (Centro di Ricerche sull'Orientamento Scolastico-professionale e sullo Sviluppo delle organizzazioni dell'Università Cattolica del Sacro Cuore di Milano) sia con i servizi alla persona interni all'università sia con enti esterni al fine di garantire servizi orientativi adeguati ai bisogni della persona. / The introduced search becomes part in the University Guideline which study of new methodologies in topic of guideline demanded from the University Reform (the Law delegation 127 of 1997). With the new university system, the guideline acquires an important relief, as a matter of fact, the D.M. 509/99, in performance to the law 127/97, includes the guideline between the formative activities that must obligatorily be previewed in the didactic regulations of athenaeum. The aforesaid scene has motivated the present such search to inside preview of the Università Cattolica del Sacro Cuore di Milano as an participation of orientativa acceptance anticipated and integrated that becomes part in the activities inborn in the Progetti ponte to support the new matriculations to the taken one of orientativa decision, in order to receive adequately the students in university and to favor of the insertion in the new context of studies. This is, therefore, a search applied with the purpose to estimate the distributed service of acceptance. This reflection on new methodologies of orientativa action has delineated new collaborations of the CROSS (Centro di Ricerche sull'Orientamento Scolastico-professionale e sullo Sviluppo delle organizzazioni dell'Università Cattolica del Sacro Cuore di Milano) with the inner services to the person to this university and with external agencies to the aim to guarantee services oriented adapts to the needs of the person.
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