Utilizzando la chiave BCHome si passa al sito corrispondente. Esso e' fatto da piu' parti: nella prima viene elencato e descritto tutta la parte del bootstrap usata, nella seconda e' inserito un ampio glossario, nella terza e' effettivamente mostrato il funzionamento in JAVA del bootstrap, per esempio da MEDIA, la MEDIA PESATA, la MEDIANA, la VARIANZA e la CORRELAZIONE: infine e' mostrato anche il modo per generare un nuovo accesso. I dati da elaborare possono essere di tipi diversi: ambientali, topografici, chimici, metrologici.
Sistema interattivo per la segmentazione di immagini a colori basato sulla soluzione numerica, mediante tecnica fast marching, di un modello eikonale. Il sistema, in particolare è orientato all'estrazione di aree di degrado di materiali lapidei.
Segmentaz
colore
fast marching
degrado
approssimazione numerica
The present paper deals with the following hyperbolic-elliptic coupled system, modelling dynamics of a gas in presence of radiation,
{(-qxx + Rq + G center dot ux = 0,) (ut + f(u)x + Lqx = 0,) x is an element of R, t > 0,
where u is an element of R-n, q is an element of R and R > 0, G, L is an element of R-n. The function f : R-n -> R-n is smooth and such that del f has n distinct real eigenvalues for any u.
The problem of existence of admissible radiative shock wave is considered, i.e., existence of a solution of the form
(u, q)(x, t) := (U, Q)(x - st),
such that (U, Q)(+/-infinity) = (u(+/-), 0), and u(+/-) is an element of R-n, s is an element of R define a shock wave for the reduced hyperbolic system, obtained by formally putting L = 0.
It is proved that, if u(-) is such that del lambda(k)(u(-)) center dot r(k)(u(-)) not equal 0 (where lambda(k) denotes the k-th eigenvalue of del f and r(k) a corresponding right eigenvector), and
(l(k)(u(-)) center dot L) (G center dot r(k)(u(-))) > 0,
then there exists a neighborhood u of u(-) such that for any u(+) is an element of u, s is an element of R such that the triple (u(-), u(+); s) defines a shock wave for the reduced hyperbolic system, there exists a (unique up to shift) admissible radiative shock wave for the complete hyperbolic-elliptic system.
The proof is based on reducing the system case to the scalar case, hence the problem of existence for the scalar case with general strictly convex fluxes is considered, generalizing existing results for the Burgers' flux f(u) = u(2)/2. Additionally, we are able to prove that the profile (U, Q) gains smoothness when the size of the shock vertical bar u(+) - u(-)vertical bar is small enough, as previously proved for the Burgers' flux case.
Finally, the general case of nonconvex fluxes is also treated, showing similar results of existence and regularity for the profiles.
We introduce new Laguerre-type population dynamics models. These models arise quite naturally by substituting in classical models the ordinary derivatives with the Laguerre derivatives and therefore by using the so called Laguerre-type exponentials instead of the ordinary exponential. The L-exponentials e(n)(t) are increasing convex functions for t >= 0, but increasing slower with respect to exp t. For this reason these functions are useful in order to approximate different behaviors of population growth. We consider mainly the Laguerre-type derivative D(t)tD(t), connected with the L-exponential el(t), and investigate the corresponding modified logistic, Bernoulli and Gompertz models. Invariance of the Volterra-Lotka model is mentioned. (C) 2006 Elsevier Inc. All rights reserved.
Laguerre-type derivative
Laguerre-type exponentials
population dynamics models
Following some general ideas on the discrete kinetic and stochastic game theory proposed by one of the authors in a previous work, this paper develops a discrete velocity mathematical model for vehicular traffic along a one-way road. The kinetic scale is chosen because, unlike the macroscopic one, it allows to capture the probabilistic essence of the interactions among the vehicles, and offers at the same time, unlike the microscopic one, the opportunity of a pro. table analytical investigation of the relevant global features of the system. The discretization of the velocity variable, rather than being a pure mathematical technicality, plays a role in including the intrinsic granular nature of the flow of vehicles in the mathematical theory of traffic. Other important characteristics of the model concern the gain and loss terms of the kinetic equations, namely the construction of a density-dependent table of games to model velocity transitions and the introduction of a visibility length to account for nonlocal interactions among the vehicles.
traffic flow modeling
discrete kinetic theory
probabilistic interactions
table of games
interaction length
A mathematical model of the tumour growth along a blood vessel is proposed. The model employs the mixture theory approach to describe a tissue which consists of cells, extracellular matrix and liquid. The growing tumour tissue is supposed to be surrounded by the host tissue. Tumours where complete oxydation of glucose prevails are considered. Special attention is paid to consistent description of oxygen consumption and growth processes based on the energy balance. A finite difference numerical method is proposed. The level set method is used to track an interface between the tissues. The simulations show localization of the tumour within a limited distance from the vessels and constant expansion velocity along the vessels.
tumour growth
hypoxia
tumour cords
tumour-host interface
mathematical model
mixture theory
finite difference
level set method
The duality between service providers and services consumers is a basic pattern of service oriented computing. A service oriented approach to business processes and to adaptive interacting processes requires an additional pattern based on the, possibly online, interaction between specification, execution and evaluation of basic processes. These two patterns combine into composed processes: the foundations of complex adaptive services. The management of the dynamics of such services is then obtained by additional processes distributed over the network of interactions of the basic and composed processes. The double triad architecture so obtained is inspired from quark-antiquark models of particle physics.
