L'articolo riassume il quadro dei risultati noti circa il cosiddetto problema di Stefan con sopraraffreddamento. Con ciò si intende in senso lato l'estensione del modello di Stefan a quei casi in cui la temperatura della fase liquida (solida) non è confinata al di sopra (sotto) di quella di cambiamento di fase, supposta costante. La nostra discussione è prevalentemente rivolta allo sviluppo di singolarità (non limitatezza della velocità dell'interfaccia, ecc.), al modo di prevederle, di prevenirle...
Waxy Crude Oils (WCO’s) are characterized by the presence of heavy paraffins in
sufficiently large concentrations. They exhibit quite complex thermodynamical and
rheological behaviour and present the peculiar property of giving rise to the formation of
segregated wax deposits, when temperature falls down the so called WAT, or Wax Appearance
Temperature. In extreme cases, segregated waxes may lead to pipeline occlusion due to
deposition on cold walls....
Mathematical models of tumour spheroids, proposed since the early seventies, have been
generally formulated in terms of a single diffusive nutrient which is critical for cell replication
and cell viability. Only recently, attempts have been made to incorporate in the models the cell
energy metabolism, by considering the interplay between glucose, oxygen and lactate (or pH).
By assuming glucose and lactate as the only fuel substrates, we propose a simple model for the
cell ATP production which takes...
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