Search results for "Modell"

Three-mode two-boson Jaynes–Cummings model in trapped ions

2006

In this paper, we analyse a two-boson three-mode Jaynes–Cummings model which can be implemented in the context of trapped ions. The symmetries of the Hamiltonian are brought to light and analysed in detail in order to solve the eigenvalue problem. The calculation of the time evolution operator shows the possibility of realizing interesting applications, such as the generation of nonclassical states.

The Origin of Isolated Populations of the Mountain Weevil, Liparus glabrirostris—The Flagship Species for Riparian Habitats

2020

AbstractLiparus glabrirostris is one of the largest European weevils, and it has been recently proposed as the flagship species for threatened riparian habitats in the mountains. For effective conservation of its populations (and associated habitats), it is crucial to understand its history, contemporary distribution, genetic diversity and predict changes in the range, including its highly isolated populations on the Baltic coast. Here, we examined numerous populations of L. glabrirostris across almost the entire species range using phylogeography and species niche modeling (SNM) approaches. Analyses of mtDNA and nucDNA markers revealed the existence of 2 major mitochondrial lineages genera…

Geographic Distribution and Niche Divergence of Two Stinkbugs,Parastrachia japonensisandParastrachia nagaensis

2014

Parastrachiidae is a small stinkbug family containing only one genus and two species, Parastrachia japonensis (Scott) (Hemiptera: Heteroptera: Pentatomoidea) and Parastrachia nagaensis Distant. The geographic distribution of the genus has been poorly studied. Niche conservatism refers to that idea that closely related species are more ecologically similar than would be expected, whereas niche divergence predicts they occupy distinct niche spaces. The existence of only two species within one genus suggests niche conservatism or differentiation might exist among them. Herein, the distribution of the genus was mapped, potential distributions were predicted using ecological niche modeling, and …

Dynamic analysis for axially moving viscoelastic panels

2012

In this study, stability and dynamic behaviour of axially moving viscoelastic panels are investigated with the help of the classical modal analysis. We use the flat panel theory combined with the Kelvin–Voigt viscoelastic constitutive model, and we include the material derivative in the viscoelastic relations. Complex eigenvalues for the moving viscoelastic panel are studied with respect to the panel velocity, and the corresponding eigenfunctions are found using central finite differences. The governing equation for the transverse displacement of the panel is of fifth order in space, and thus five boundary conditions are set for the problem. The fifth condition is derived and set at the in-…

Long-range cohesive interactions of non-local continuum faced by fractional calculus

2008

Abstract A non-local continuum model including long-range forces between non-adjacent volume elements has been studied in this paper. The proposed continuum model has been obtained as limit case of two fully equivalent mechanical models: (i) A volume element model including contact forces between adjacent volumes as well as long-range interactions, distance decaying, between non-adjacent elements. (ii) A discrete point-spring model with local springs between adjacent points and non-local springs with distance-decaying stiffness connecting non-adjacent points. Under the assumption of fractional distance-decaying interactions between non-adjacent elements a fractional differential equation in…

Fractional visco-elastic Euler–Bernoulli beam

2013

Abstract Aim of this paper is the response evaluation of fractional visco-elastic Euler–Bernoulli beam under quasi-static and dynamic loads. Starting from the local fractional visco-elastic relationship between axial stress and axial strain, it is shown that bending moment, curvature, shear, and the gradient of curvature involve fractional operators. Solution of particular example problems are studied in detail providing a correct position of mechanical boundary conditions. Moreover, it is shown that, for homogeneous beam both correspondence principles also hold in the case of Euler–Bernoulli beam with fractional constitutive law. Virtual work principle is also derived and applied to some c…

Models and Phenomena: Bas van Fraassen’s Empiricist Structuralism

2013

Bas van Fraassen’s recent endorsement of empiricist structuralism is based on a particular approach to representation. He sharply distinguishes between what makes a scientific model M a successful representation of its target T from what makes M a representation of T and not of some other different target T’. van Fraassen maintains that embedment (i.e.: a particular sort of isomorphism which relates structures) gives the answer to the first question while the user’s decision to employ model M to represent T accounts for the representational link. After discussing the rationale for this approach, I defend that indexical constraints like those favoured by van Fraassen cannot be the last word …

Analisi del processo di consumo istantaneo di singole utenze residenziali con il modello di Poisson ad impulsi rettangolari

2008

A network model for the short-term prediction of the evolution of cocaine consumption in Spain

2010

Cocaine consumption is a social problem with acute consequences and its dependency can be regarded as a health concern of social transmission. This fact leads us to develop the idea that its transmission dynamics can be studied using epidemiological mathematical models. Under this point of view, in this paper we propose a network model to study the short-term evolution of the cocaine consumer subpopulations. The model parameters are obtained from data source and from an analogue continuous model. Sensitivity of the model parameters is studied. The parameters are associated with prevention and treatment policies and the sensitivity study gives us information about which parameters have more …

Novel Energy Modelling and Forecasting Tools for Smart Energy Networks

2015

A novel Energy Modelling and Forecasting Tool (EMFT) has been adopted for use in the VIM SEN (Virtual Microgrids for Smart Energy Networks) project and this paper gives an insight of the techniques used to provide vital support to the energy market, in particular to energy aggregators. A brief description of one of the test sites where data has been collected for validation of the EMFT will be outlined and some examples shown. The information and predictions will then be used by a decision support system to dynamically adjust energy delivery and consumption, by giving advice to users and operators on actions they can take to obtain a better match between energy supply and demand that increa…