The search session has expired. Please query the service again.
The search session has expired. Please query the service again.
Motivated by structured parasite populations in aquaculture we consider a class of
size-structured population models, where individuals may be recruited into the population
with distributed states at birth. The mathematical model which describes the evolution of
such a population is a first-order nonlinear partial integro-differential equation of
hyperbolic type. First, we use positive perturbation arguments and utilise results from
the spectral...
The influence of emission levels on the concentrations of four important air pollutants (ammonia, ozone, ammonium sulphate and ammonium nitrate) over three European cities (Milan, Manchester, and Edinburgh) with different geographical locations is considered. Sensitivity analysis of the output of the Unified Danish Eulerian Model according to emission levels is provided. The Sobol’ variance-based approach for global sensitivity analysis has been applied to compute the corresponding sensitivity measures....
In a typical moving contaminating source identification problem, after some type of biological or chemical contamination has occurred, there is a developing cloud of dangerous or toxic material. In order to detect and localize the contamination source, a sensor network can be used. Up to now, however, approaches aiming at guaranteeing a dense region coverage or satisfactory network connectivity have dominated this line of research and abstracted away from the mathematical description of the physical...
Due to wide range of interest in use of bio-economic models
to gain insight into the scientific management of renewable resources like
fisheries and forestry,variational iteration method (VIM) is employed to
approximate the solution of the ratio-dependent predator-prey system with
constant effort prey harvesting.The results are compared with the results
obtained by Adomian decomposition method and reveal that VIM is very
effective and convenient for solving nonlinear differential equations.
En esta nota se analizan dos modelos matemáticos deterministas planteados en problemas ecológicos causados por la introducción de nuevas especies en ambientes insulares heterogéneos. En el primero desarrollamos un modelo epidemológico con transmisión indirecta del virus por medio del ambiente. En el segundo se introduce un modelo específico de depredador-presa que exhibe la extinción en tiempo finito de las especies. Ambos modelos involucran sistemas de ecuaciones en derivadas parciales con interesantes...
In this article we discuss some issues related to Air Pollution modelling (as viewed by the authors): subgrid parametrization, multiphase modelling, reduction of high dimensional models and data assimilation. Numerical applications are given with POLAIR, a 3D numerical platform devoted to modelling of atmospheric trace species.
We consider a broad class of stochastic lattice predator-prey models whose main features are overviewed. In particular, this article aims at drawing a picture of the influence of spatial fluctuations, which are not accounted for by the deterministic rate equations, on the properties of the stochastic models. Here, we outline the robust scenario obeyed by most of the lattice predator-prey models with an interaction à la Lotka-Volterra. We also show how a drastically different behavior can emerge...
In this paper, we investigate the complex dynamics of a spatial plankton-fish system with
Holling type III functional responses. We have carried out the analytical study for both
one and two dimensional system in details and found out a condition for diffusive
instability of a locally stable equilibrium. Furthermore, we present a theoretical
analysis of processes of pattern formation that involves organism distribution and their
interaction of spatially...
For an SI type endemic model with one host and two parasite strains, we study the
stability of the endemic coexistence equilibrium, where the host and both parasite strains
are present. Our model, which is a system of three ordinary differential equations,
assumes complete cross-protection between the parasite strains and reduced fertility and
increased mortality of infected hosts. It also assumes that one parasite strain is
exclusively vertically...
In the present study the notion of watershed contour dynamics, defined within the framework of mathematical morphology, is examined. It is shown that the dynamics are a direct measure of the “sharpness” of transition between neighboring watershed basins. The expressions for the expected value and the statistical error of the estimation of contour dynamics are derived in the presence of noise, based on extreme value theory. The sensitivity of contour dynamics to noise is studied. A statistical approach...
Finite-size fluctuations arising in the dynamics of competing populations may have dramatic influence on their fate. As an example, in this article, we investigate a model of three species which dominate each other in a cyclic manner. Although the deterministic approach predicts (neutrally) stable coexistence of all species, for any finite population size, the intrinsic stochasticity unavoidably causes the eventual extinction of two of them.
This work introduces how possibilistic regression can be used in the case of non symmetrical triangular membership functions, building a system of regressions, so that suitable restrictions for each particular problem can be incorporated. We apply this methodology to the problem of ecological inference, in particular to the estimation of the electoral transition matrix. An experimentation with several examples shows the benefits of the new approach.
Currently displaying 1 –
18 of
18