Sökning: "sigma"

Visar resultat 6 - 10 av 151 avhandlingar innehållade ordet sigma.

1. 6. 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

3. 7. Modeling and Analysis of Wideband Sigma-Delta Noise Shapers

   Författare :Andreas Göthenberg; KTH; []
   Nyckelord :Data Converters; Oversampling; Sigma-Delta; Modulators; Wideband; Noise Shapers; Sampling Switches; Substrate Noise Coupling;

   Sammanfattning : The continuous evolution of CMOS technologies towards deepsubmicron processes has provided new opportunities forintegration of mixed-signal systems on single monolithicintegrated circuits. In order to find the optimal usage of CMOStechnology and robustness against undesired mixed-signalcouplings, new approaches to CMOS front-end integration areneeded. LÄS MER

4. 8. Twisting and Gluing : On Topological Field Theories, Sigma Models and Vertex Algebras

   Författare :Johan Källén; Maxim Zabzine; Mathias Blau; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Topological field theory; Chern-Simons theory; Contact geometry; Sigma models; Poisson vertex algebras; Vertex algebras; String theory; Theoretical Physics; Teoretisk fysik;

   Sammanfattning : This thesis consists of two parts, which can be read separately. In the first part we study aspects of topological field theories. We show how to topologically twist three-dimensional N=2 supersymmetric Chern-Simons theory using a contact structure on the underlying manifold. LÄS MER

5. 9. Continuous-Time Delta-Sigma Modulators for Ultra-Low-Power Radios

   Författare :Dejan Radjen; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Delta-Sigma; continuous-time; analog-to-digital; ultra-low-power; clock jitter; single operational amplifier; SAR quantizer;

   Sammanfattning : The modern small devices of today require cheap low power radio frequency (RF) transceivers that can provide reliable connectivity at all times. In an RF transceiver, the analog-to-digital converter (ADC) is one of the most important parts and it is also one of the main power consumers. LÄS MER

7. 10. Six Sigma management. Action research with some contributions to theories and methods

   Författare :Peter Cronemyr; Bo Bergman; Bjarne Bergquist; Swedeb Gothenburg Chalmers University of Technology Department of Technology Management and Economics; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Six Sigma; Process Management; Action Research; Customer Feedback; Process Door; Knowledge Overlapping; DMADC; Process Simulations.;

   Sammanfattning : Many companies around the world have implemented Six Sigma as a problem solving methodology especially useful for dealing with recurring problems in business processes. Since the 1980s when it was developed at Motorola, many companies have tried to implement Six Sigma to fit their own company’s culture and goals. LÄS MER