Academic literature on the topic 'Volterra type process'

Investigation of how spatial processes affect the maintenance of biodiversity and its geographic distribution has led to landmark contributions in community ecology. Theory has followed a logical complexification of the objects of study, with specific models at each step, from populations connected by dispersal to ecosystems connected by flows of energy and material. This large body of theory is not only diverse in the questions it addresses, and the scales and organization levels it encompasses, but also in the types of models used to represent spatial dynamics. Unfortunately, this makes it hard to establish clear, standard, quantitative predictions stemming from a coherent mathematical formalism. Here our objectives are : i) to propose a general metacommunity model that allows the investigation of spatial ecology from populations to entire food webs ; ii) use the model to review a set of principles driving coexistence in all types of metacommunities; iii) reveal how these principles constrain the spatial distribution of diversity, with a particular emphasis on species co-distribution. The model is based on the well-established representation of spatial dynamics through colonization and extinction processes. We generalize Levins’ metapopulation model to all types of ecological interactions, using a formalism akin to Lotka–Volterra equations for local community dynamics. Doing so, we revisit coexistence mechanisms proposed for competitive metacommunities, along with the assembly dynamics for spatial food webs and mutualistic interactions.

Parametric motion is the phenomenon where a structure is excited into large amplitude motion even when there is no direct excitation. A well-known example of this type of motion is the parametric roll of ships in head or following seas. Parametric roll of container ships in head seas is relatively a new problem which has gained much importance after the catastrophic incidence of APL China in 1998. Although a lot of analytical techniques are available on the assessment of parametric roll in regular excitation, not many investigations have explored its occurrence in irregular seas. A consensus o

A typical mechatronic oscillator involving a tuned resistor-inductor-capacitor circuit driven by a voltage source and coupled to a mass-spring-damper mechanical subsystem is analyzed in order to develop a nonlinear control model. The analysis is approached using the Volterrra/Wiener framework of nonlinear systems combined with the Hilbert Transform. The former is needed since the coupling between the electrical and mechanical parts is lost, should standard linearization is adopted. The latter is needed since a very important characteristic of the system, due to the presence of the capacitance,