Sökning: "Cyclic symmetry"

Hittade 5 avhandlingar innehållade orden Cyclic symmetry.

1. 1. Symmetry of Halonium Complexes in Solution

   Författare :Anna-Carin Carlsson; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; bis pyridine -based halonium complexes; ethylenehalonium ions; structure symmetry; isotopic perturbation of equilibrium; solution NMR spectroscopy; isotope effects; N-X -N halogen bond; C-X -C interaction;

   Sammanfattning : In this thesis the symmetry of two interaction types involving electropositive halogens have been studied in solution; the N-X+-N halogen bond (X = Br or I), and the C-X+-C interaction of previously characterised, cyclic, 1,2-bridged halonium ions (X = Cl or Br), respectively. The three N-X+-N model structures included are bispyridine, 1,2-bis(pyridine-2-ylethynyl)benzene and 1,2-bis((4-methylpyridin-2-yl)ethynyl)benzene halonium triflate complexes. LÄS MER

3. 2. On efficient and adaptive modelling of friction damping in bladed disks

   Författare :Mohammad Afzal; Leif Kari; Ines Lopez Arteaga; Muzio M Gola; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; High cycle fatigue; Friction contact; Jacobian matrix; Shroud contact; Strip damper; Multiharmonic balance method; Contact stiffness; Cyclic symmetry; Nodal diameter; Magnetostrictive actuator; Magnetic field; Engineering Mechanics; Teknisk mekanik;

   Sammanfattning : This work focuses on efficient modelling and adaptive control of friction damping in bladed disks. To efficiently simulate the friction contact, a full-3D time-discrete contact model is reformulated and an analytical expression for the Jacobian matrix is derived that reduces the computation time drastically with respect to the classical finite difference method. LÄS MER

4. 3. Models of NADH with C2 and D2 Symmetry

   Författare :Klas Skog; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : A novel supramolecular approach to the design of NADH models is presented in this dissertation. The models can be divided into two types, C2 symmetric and D2 symmetric macrocyclic structures. The C2 symmetric models are made from a chiral C2 symmetric unit, two dihydronicotinamide units and a phenylene spacer, to form a macrocyclic structure. LÄS MER

5. 4. Structure-aided design of antiviral drugs : Application of the method on HIV-1 protease and SIV reverse transcriptase

   Författare :Hans Ola Andersson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Developmental biology; HIV; protease; SIV; reverse transcriptase; structure; inhibitor; drug design; Utvecklingsbiologi; Developmental biology; Utvecklingsbiologi; molekylärbiologi; Molecular Biology;

   Sammanfattning : Many efforts have been made to control the AIDS epidemic. Extensive studies have been done on the biology, biochemistry, and structural biology of HIV in the search for antiviral drugs. The viral-encoded enzymes reverse transcriptase and protease have been main targets for drug design. LÄS MER

7. 5. Numerical modelling and analysis of friction contact for turbine blades

   Författare :Mohammad Afzal; Leif Kari; Viktor Berbyuk; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Vehicle and Maritime Engineering; Farkostteknik;

   Sammanfattning : High cycle fatigue failure of turbine and compressor blades due to resonance in the operating frequency range is one of the main problems in the design of gas turbine engines. To suppress excessive vibrations in the blades and prevent high cycle fatigue, dry friction dampers are used by the engine manufacturers. LÄS MER