Sökning: "Sigma model"

Visar resultat 1 - 5 av 56 avhandlingar innehållade orden Sigma model.

  1. 1. Continuous-Time Delta-Sigma Modulators for Wireless Communication

    Författare :Mattias Andersson; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; return-to-zero; A D converter; loop delay; delta-sigma; ADC; CMOS; STF; continuous-time; sigma; delta; filtering; CT; RZ;

    Sammanfattning : The ever increasing data rates in wireless communication require analog to digital converters (ADCs) with greater requirements on speed and accuracy, while being power efficient to prolong battery life. This dissertation contains an introduction to the field and five papers that focus on the continuous-time (CT) Delta-Sigma modulator (DSM) as ADC. LÄS MER

  3. 2. Transfer of pruduction knowledge to small and medium-size enterprises : a suggested model

    Författare :Jens von Axelson; Peter Gröndahl; KTH; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Business studies; knowledge transfer; technology transfer; SME s ; methods; tools; portfolio management; Företagsekonomi; Business studies; Företagsekonomi;

    Sammanfattning : The work that this thesis is a result of has the ambition to suggest a model forknowledge transfer to small and medium-size enterprises (SMEs). The knowledge in focus here is competitive production methods such as: leanproduction, six sigma, continuous improvement, total quality management ortotal productivity maintenance. LÄS MER

  4. 3. Going Round in Circles : From Sigma Models to Vertex Algebras and Back

    Författare :Joel Ekstrand; Maxim Zabzine; Anton Alekseev; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chiral de Rham complex; Conformal field theory; Poisson vertex algebra; Sigma model; String theory; Vertex algebra; Theoretical Physics; Teoretisk fysik;

    Sammanfattning : In this thesis, we investigate sigma models and algebraic structures emerging from a Hamiltonian description of their dynamics, both in a classical and in a quantum setup. More specifically, we derive the phase space structures together with the Hamiltonians for the bosonic two-dimensional non-linear sigma model, and also for the N=1 and N=2 supersymmetric models. LÄS MER

  5. 4. Anyons and antiferromagnets : two two-dimensional topics

    Författare :Torbjörn Einarsson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; antiferromagnet; two dimension; anyons; fractional statistics; Heisenberg model; torus; nonlinear sigma model; multi-component wavefuntions; spin; Néel phase; disorder; braid group;

    Sammanfattning : .... LÄS MER

  7. 5. Tensionless Strings and Supersymmetric Sigma Models : Aspects of the Target Space Geometry

    Författare :Andreas Bredthauer; Ulf G. Lindström; Bengt E.W. Nilsson; Uppsala universitet; []
    Nyckelord :Theoretical physics; Theoretical Physics; String Theory; Tensionless Strings; Supergravity Backgrounds; Plane Wave; Supersymmetry; Non-linear Sigma Models; Generalized Complex Geometry; Teoretisk fysik;

    Sammanfattning : In this thesis, two aspects of string theory are discussed, tensionless strings and supersymmetric sigma models.The equivalent to a massless particle in string theory is a tensionless string. Even almost 30 years after it was first mentioned, it is still quite poorly understood. LÄS MER