Sökning: "branching process"

Visar resultat 6 - 10 av 68 avhandlingar innehållade orden branching process.

  1. 6. Multi-trait Branching Models with Applications to Species Evolution

    Författare :Daniah Tahir; Ingemar Kaj; Martin Lascoux; Asger Hobolth; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Markov models; branching processes; density dependence; discrete traits; species trees; diversification rates; diffusion approximation;

    Sammanfattning : This thesis provides an analysis of the evolution of discrete traits and their effect on the birth and survival of species using the theory of supercritical, continuous time Markov branching processes. We present a branching modeling framework that incorporates multi-trait diversification processes associated with the emergence of new species, death of existing species, and transition of species carrying one type of a trait to another. LÄS MER

  3. 7. Quantitative vulnerability analysis of electric power networks

    Författare :Åke J. Holmgren; Torbjörn Thedéen; Lars-Göran Mattsson; Terje Aven; KTH; []
    Nyckelord :Safety Analysis; vulnerability; homeland security; risk analysis; network; electric power system; blackout; power law; statistical analysis; graph theory; branching process; game theory; Säkerhetsanalys; TECHNOLOGY; TEKNIKVETENSKAP;

    Sammanfattning : Disturbances in the supply of electric power can have serious implications for everyday life as well as for national (homeland) security. A power outage can be initiated by natural disasters, adverse weather, technical failures, human errors, sabotage, terrorism, and acts of war. LÄS MER

  4. 8. Accessibility percolation and first-passage percolation on the hypercube

    Författare :Anders Martinsson; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; hypercube; percolation; accessible path; house of cards; rough mount Fuji; first-passage percolation; Richardson s model; branching translation process; hypercube;

    Sammanfattning : In this thesis, we consider two percolation models on the n-dimensional binary hypercube, known as accessibility percolation and first-passage percolation. First-passage percolation randomly assigns non-negative weights, called passage times, to the edges of a graph and considers the minimal total weight of a path between given end-points. LÄS MER

  5. 9. Ultrafast Probing of CO Reactions on Metal Surfaces : Changes in the molecular orbitals during the catalysis process

    Författare :Jörgen Gladh; Henrik Öström; Nils Mårtensson; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Hetrogenous catalysis; CO; transition metals; Ultrafast probing; oxidation; desorption; dissociation; kemisk fysik; Chemical Physics;

    Sammanfattning : This thesis presents experimental studies of three different chemical reaction steps relevant for heterogeneous catalysis: dissociation, desorption, and oxidation. CO on single-crystal metal surfaces was chosen as the model systems. LÄS MER

  7. 10. Evolving ecological communities in changing environments

    Författare :Jacob Johansson; Evolutionär ekologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; adaptive dynamics; competition; community evolution; ecological communities; environmental change; evolutionary branching;

    Sammanfattning : This thesis consists of theoretical studies of the evolutionary consequences of environmental change in ecological communities. Paper I and II are concerned with the origin of diversity, i.e. how a single lineage can split into two, under the influence of selection induced by competitive interactions (evolutionary branching). LÄS MER