In bioventing, air is forced into the subsoil to exploit the biodegradation activity of bacteria.
The problem of optimization consists of choosing the best positions and volumetric flow rates of injection or extraction wells within the polluted soil.
A mathematical model for the unsaturated zone which also describes the bacteria population dynamics and the pollutant removal will be presented.
It is possible to identify several kinds of optimization criteria and the related numerical issues will be examined. Numerical tests of the model and of the optimization procedures will be shown.
We discuss solvability properties of a nonlinear hypersingular integral equation of Prandtl's type using monotonicity arguments together with different collocation iteration schemes for the numerical solution of such equations.
nonlinear hypersingular integral equation; collocation method
Scaling and hydrodynamic effects in lamellar ordering
A Xu
;
G Gonnella
;
A Lamura
;
G Amati
;
F Massaioli
We study the kinetics of domain growth of fluid mixtures quenched from a
disordered to a lamellar phase. At low viscosities, in two dimensions, when hydrodynamic
modes become important, dynamical scaling is verified in the form C(k, t) ~ L
?
f[(k - kM)L],
where C is the structure factor with maximum at kM and L is a typical length with logarithmic
growth at late times. The presence of extended defects can explain the behavior of L. Three-dimensional simulations confirm that diffuse grain boundaries inhibit complete ordering of
lamellae. Applied shear flow alleviates frustration and gives power law growth at all times.
: The relation between the position of mutations in Saccharomyces cerevisiae metabolic network and their lethality is the subject of this work. We represent the topology of the network by a directed graph: nodes are metabolites and arcs represent the reactions; a mutation corresponds to the removal of all the arcs referring to the deleted enzyme. Using publicly available knock-out data, we show that lethality corresponds to the lack of alternative paths in the perturbed network linking the nodes affected by the enzyme deletion. Such feature is at the basis of the recently recognized importance of 'marginal' arcs of metabolic networks.
