Sökning: "Linear generators"

Visar resultat 16 - 20 av 59 avhandlingar innehållade orden Linear generators.

1. 16. Around minimal Hilbert series problems for graded algebras

   Författare :Lisa Nicklasson; Samuel Lundqvist; Christian Gottlieb; Uwe Nagel; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Graded algebras; Hilbert series; Lefschetz properties; Exterior algebra; Linear resolution; Mathematics; matematik;

   Sammanfattning : The Hilbert series of a graded algebra is an invariant that encodes the dimension of the algebra's graded compontents. It can be seen as a tool for measuring the size of a graded algebra. This gives rise to the idea of algebras with a "minimal Hilbert series", among the algebras within a certain family. LÄS MER

3. 17. Theoretical and Experimental Analysis of Operational Wave Energy Converters

   Författare :Erik Lejerskog; Mats Leijon; Rafael Waters; John Ringwood; Uppsala universitet; []
   Nyckelord :ocean wave energy; WEC; permanent magnet; linear generator; closed stator slots; offshore experiments;

   Sammanfattning : This thesis studies wave energy converters developed at Uppsala University. The wave energy converters are of point absorbing type with direct driven linear generators. The aim has been to study generator design with closed stator slots as well as offshore experimental studies. LÄS MER

4. 18. Core Loss Prediction in Hydroelectric Generators and Analysis of a Contra-Rotating Machine Topology

   Författare :Martin Ranlöf; Uppsala universitet; []
   Nyckelord :TECHNOLOGY; TEKNIKVETENSKAP;

   Sammanfattning : The call for increased accuracy in the process of design and analysis of electrical machines has encouraged the use of numerical methods to calculate the electric and magnetic field distributions within this type of apparatus. The finite element method is a numerical technique that has become specifically widespread and popular, due to the relative swiftness and accuracy with which it is possible to treat complex machine geometries and non-linear material characteristics. LÄS MER

5. 19. Lefschetz Properties of Monomial Ideals

   Författare :Nasrin Altafi; Mats Boij; Alicia Dickenstein; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Weak Lefschetz property; monomial ideals; group actions; almost linear resolution; Mathematics; Matematik;

   Sammanfattning : This thesis concerns the study of the Lefschetz properties of artinian monomial algebras. An artinian algebra is said to satisfy the strong Lefschetz property if multiplication by all powers of a general linear form has maximal rank in every degree. If it holds for the first power it is said to have the weak Lefschetz property (WLP). LÄS MER

7. 20. Attenuation of boundary layer disturbances by means of streamwise vortices

   Författare :Sohrab Sattarzadeh Shirvan; Jens H. M. Fransson; Valery Chernoray; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer stability; Tollmien-Schlichting waves; oblique waves; transition to turbulence; streamwise vortices; miniature vortex generators; instability control; drag reduction;

   Sammanfattning : The stability of the boundary layer developed on a flat plate is studied in the presence of streamwise streaks where disturbances of different types are introduced in the wall-bounded shear layer. The experimental investigations are aimed at flow control by means of passively damping the energy growth of the disturbances in the streaky boundary layer and furthermore delay the onset of the transition in the streamwise direction. LÄS MER