Sökning: "modulation spaces"

Visar resultat 1 - 5 av 9 avhandlingar innehållade orden modulation spaces.

  1. 1. Propagation of singularities for pseudo-differential operators and generalized Schrödinger propagators

    Författare :Karoline Johansson; Joachim Toft; Anders Olofsson; Linnéuniversitetet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Banach spaces; Fourier; Generalized time-dependent Schrödinger equation; Micro-local; Modulation spaces; Non-tangential convergence; Pseudo-differential operators; Regularity; Wave-front sets; Banachrum; Fourier; Generaliserad tidsberoende Schrödinger ekvation; Icke-tangentiell konvergens; Mikrolokal; Modulationsrum; Pseudodifferentialoperatorer; Regularitet; Vågfrontsmängder; Mathematical analysis; Analys; Mathematics; Matematik;

    Sammanfattning : In this thesis we discuss different types of regularity for distributions which appear in the theory of pseudo-differential operators and partial differential equations. Partial differential equations often appear in science and technology. LÄS MER

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

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

    Sammanfattning : 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. LÄS MER

  4. 3. Multidimensional Modulation Formats for Coherent Optical Communication Systems

    Författare :Tobias Eriksson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; binary pulse position modulation QPSK; Fiber-optical communication; spectral efficiency; power efficiency; multidimensional position modulation.; 16-ary quadrature amplitude modulation 16QAM ; quadrature phase shift keying QPSK ; coherent detection; polarization-switched quadrature phase shift keying PS-QPSK ; 128-level set-partitioning QAM 128-SP-QAM ;

    Sammanfattning : Coherent optical receivers have enabled the use of multilevel modulation formats with high spectral efficiencies and long transmission reaches. Traditionally, modulation formats utilizing the two dimensions spanned by the amplitude and the phase of the signal have been dominating. LÄS MER

  5. 4. Properties of wave-front sets and non-tangential convergence

    Författare :Karoline Johansson; Joachim Toft; Luigi Rodino; Linnéuniversitetet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fourier Banach spaces; Generalized free time-dependent Schrödinger equation; Micro-local; Modulation spaces; Non-tangential convergence; Pseudo-differential operators; Regularity; Wave-front sets.; Mathematical analysis; Analys; Matematik; Mathematics;

    Sammanfattning : In this thesis we consider regularity properties for solutions to partial differential equations and pseudo-differential equations. The thesis mainly concerns wave-front sets and micro-local properties. LÄS MER

  7. 5. Biological optimization of angle of incidence and intensity modulation in breast and cervix cancer radiation therapy

    Författare :Brigida Costa Ferreira; Anders Brahme; Roger Svensson; Ion Christian Chiricuta; Stockholms universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; biological treatment planning; angle of incidence optimization; intensity modulation; breast and cervix cancer; Radiation biology; Strålningsbiologi;

    Sammanfattning : Biological treatment optimization aim at improving radiation therapy by accounting for the radiobiological tumour and normal tissues response properties when optimizing the dose delivery. Generally traditional methods, using only dosimetrical measures, disregard the nonlinear radiation response of different tumours and normal tissues. LÄS MER