Uno degli interventi proposti dal protocollo di Kyoto per la stabilizzazione delle concentrazionidi gas serra si riferisce alla necessità di determinare la localizzazione delle sorgenti e delle fonti ditali gas. Il metodo del bilancio di massa, implementato a partire da misure rilevate da piattaforma aerea,presenta la potenzialità di poter quantificare gli scambi gassosi superficiali su aree di diversi chilometriquadrati, permettendo una stima anche in condizioni di eterogeneità superficiale, contrariamente ai metoditradizionali. In questo studio il metodo è stato applicato ad un sito nei pressi di Forlì utilizzando dati telerilevatiad alta frequenza nello strato limite planetario. La scarsa risoluzione verticale ottenuta in fase dirilevamento dati è stata risolta attraverso un metodo di regressione non parametrico. I campi di concentrazionedel gas e del vento in corrispondenza dell'altezza dello strato limite planetario sono determinaticon un modello additivo non parametrico. Risulta che la superficie del territorio esaminato emette un flussodi anidride carbonica di 13±0.3 ?moli/m2/s, a causa della presenza di un centro industriale all'internodell'area esaminata.

A simple and efficient numerical method for solving the advection equation on the spherical surface is presented. To overcome the well-known ‘pole problem’ related to the polar singularity of spherical coordinates, the space discretization is performed on a geodesic grid derived by a uniform triangulation of the sphere; the time discretization uses a semi-Lagrangian approach. These two choices, efficiently combined in a substepping procedure, allow us to easily determine the departure points of the characteristic lines, avoiding any computationally expensive tree-search. Moreover, suitable interpolation procedures on such geodesic grid are presented and compared. The performance of the method in terms of accuracy and efficiency is assessed on two standard test cases: solid-body rotation and a deformation flow.

A hollow-fiber enzyme reactor, operating under isothermal and nonisothermal conditions, was built employing a polypropylene hollow fiber onto which â-galactosidase was immobilized. Hexamethylenediamine and glutaraldehyde were used as spacer and coupling agent, respectively. Glucose production was studied as a function of temperature, substrate concentration, and size of the transmembrane temperature gradient. The actual average temperature differences across the polypropylene fiber, to which reference was done to evaluate the effect of the nonisothermal conditions, were calculated by means of a mathematical approach, which made it possible to know, using computer simulation, the radial and axial temperature profiles inside the bioreactor and across the membrane. Percent activity increases, proportional to the size of the temperature gradients, were found when the enzyme activities under nonisothermal conditions were compared to those measured under comparable isothermal conditions. Percent reductions of the production times, proportional to the applied temperature gradients, were also calculated. The advantage of employing nonisothermal bioreactors in biotechnological industrial process was discussed.

Dalla locandina della manifestazione: Il mistero dello spazio infinito si accompagna al mistero dell'infinita' dei numeri. Vivremo un viaggio attraverso i segreti dello spazio sotto la guida di numeri magici. Scopriremo il messaggio universale dei numeri, seguiremo in diretta la traccia dei satelliti e capiremo come ci osservano dallo spazio attraverso attivita' multimediali ed una Tavola Rotonda. Metteremo alla prova le nostre conoscenze sullo spazio attraverso quiz e cruciverba. I piu' piccoli potranno costruire semplici modellini di astronavi e cominciare a sognare avventure spaziali."

A semi-implicit semi-Lagragian mixed finite-difference finite-volume model for the shallow water equations on a rotating sphere is considered The main features of the model are the finite-volume approach for the continuity equation and the vectorial treatment of the momentum equation. Pressure and Coriolis terms in the momentum equation and velocity in the continuity equation are treated semi-implicitly. Discretization of this model led to the introducion, in a previous paper, of a splitting technique which highly reduces the computational effort for the numerical solution. In this paper we solve the full set of equations, without splitting, introducing an ad hoc algorithm A von Neumann stability analysis of this scheme is performed to establish the unconditional stability of the new proposed method Finally, we compare the efficiency of the two approaches by numerical experiments on a standard test problem Results show that due to the devised algorithm, the solution of the full system of equations is much more accurate while slightly increasing the computational cost. A semi-implicit semi-Lagrangian mixed finite-difference finite-volume model for the shallow water equations on a rotating sphere is considered. The main features of the model are the finite-volume approach for the continuity equation and the vectorial treatment of the momentum equation. Pressure and Coriolis terms in the momentum equation and velocity in the continuity equation are treated semi-implicitly. Discretization of this model led us to introduce, in a previous paper, a splitting technique which highly reduces the computational effort for the numerical solution. In this paper we solve the full set of equations, without splitting, introducing an 'ad hoc' algorithm. A von Neumann stability analysis of this scheme is performed to establish the unconditional stability of the new proposed method. Finally, we compare the efficiency of the two approaches by numerical experiments on a standard test problem. Our results show that, due to the devised algorithm, the solution of the full system of equations is much more accurate while slightly increases the computational cost.