Search for dissertations about: "composition operator"

Showing result 1 - 5 of 10 swedish dissertations containing the words composition operator.

  2. 1. Continuity and compositions of operators with kernels in ultra-test function and ultra-distribution spaces

    Author : Yuanyuan Chen; Joachim Toft; Nenad Teofanov; Linnéuniversitetet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Composition; modulation spaces; positivity; pseudo-differential operators; Schatten-von Neumann operators; twisted convolutions; ultra-distributions; Matematik; Mathematics;

    Abstract : In this thesis we consider continuity and positivity properties of pseudo-differential operators in Gelfand-Shilov and Pilipović spaces, and their distribution spaces. We also investigate composition property of pseudo-differential operators with symbols in quasi-Banach modulation spaces. READ MORE

  4. 2. Analysis of Structure, Composition and Growth of Semiconductor Nanowires by Transmission Electron Microscopy

    Author : Martin Ek; Centrum för analys och syntes; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Transmission electron microscopy; nanowires; III-V semiconductors; polarity; in-situ TEM;

    Abstract : Nanowires have the potential to be a very flexible platform for the design of semiconductor devices. In nanowires it is possible to form crystal structures not found in the bulk materials under normal conditions, and to combine different III-V and group IV materials into axial or radial heterostructures. READ MORE

  5. 3. Construction of Representations of Commutation Relations by Linear Operators in Banach Spaces

    Author : Domingos Djinja; Sergei Silvestrov; Samuel Lopes; Mälardalens universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Mathematics Applied Mathematics; matematik tillämpad matematik;

    Abstract : This thesis is devoted to the construction and investigation of some properties of pairs of linear operators (A, B) (representations) satisfying commutation relations AB=BF(A), where F denotes certain polynomial. Commutation relations of this kind are called "covariance type" and finding their representations is equivalent to solving operator equations. READ MORE

  6. 4. On time-frequency analysis and pseudo-differential operators for vector-valued functions

    Author : Patrik Wahlberg; Joachim Toft; Luigi Rodino; Växjö universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; MATHEMATICS; MATEMATIK;

    Abstract : This thesis treats different aspects of time-frequency analysis and pseudodifferential operators, with particular emphasis on techniques involving vector-valued functions and operator-valued symbols. The vector (Banach) space is either motivated by an application as in Paper I, where it is a space of stochastic variables, or is part of a general problem as in Paper II, or arises naturally from problems for scalar-valued operators and function spaces, as in Paper V. READ MORE

  7. 5. Modelling the microstructural changes in steels due to fusion welding

    Author : John Ion; Luleå tekniska universitet; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materialteknik; Engineering Materials;

    Abstract : Theoretical, physically-based models of fusion welding are developed, and calibrated using experimental data from practical welds. The following heat-affected zone phenomena are investigated: grain growth, precipitate dissolution and coarsening, martensite formation and hardness. READ MORE