Search for dissertations about: "aerodynamics evolution"

Showing result 1 - 5 of 8 swedish dissertations containing the words aerodynamics evolution.

2. 1. Pollen and pollination in Ephedra (Gnetales)

   Author : Kristina Bolinder; Catarina Rydin; Johan Ehrlén; Michael S Zavada; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; aerodynamics; evolution; moonlight; pollination; pollen morphology; ultrastructure; växtsystematik; Plant Systematics;

   Abstract : Ephedra (Gnetales) is a gymnosperm genus with a long evolutionary history; the first dispersed pollen grains with affinity to the group are known already from the Permian. This thesis focuses on the evolutionary history of the group and different aspects of its pollination mechanisms. READ MORE

4. 2. Wakes behind wind turbines - Studies on tip vortex evolution and stability

   Author : Ylva Odemark; Jens Fransson; Jens Madsen; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wind power; aerodynamics; hot-wire anemometry; vortex dynamics;

   Abstract : The increased fatigue loads and decreased power output of a wind turbine placed in the wake of another turbine is a well-known problem when building new wind power farms. In order to better estimate the total power output of a wind power farm, knowledge about the development and stability of wind turbine wakes is crucial. READ MORE

5. 3. Feathers by day, membranes by night - Aerodynamic performance in bird and bat flight

   Author : Florian Muijres; Evolutionär ekologi; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; animal flight; aerodynamics; vortex wake; actuator disk; flight performance; span efficiency; bird; bat; wind tunnel; PIV; Pied Flycatcher; Glossophaga soricina; Leptonycteris yerbabuenae;

   Abstract : The efficiency and performance of a flying animal is directly related to the aerodynamics around its body and flapping wings. Here, I have developed methods for quantifying the wake dynamics around a flying animal. The results are used to estimate the aerodynamic performance of flapping flight. READ MORE

6. 4. Development of Separation Phenomena on a Passenger Car

   Author : Sabine Bonitz; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; complex flows; vortex formation; vehicle aerodynamics; flow separation; limiting streamlines; crossflow separation;

   Abstract : The general shape of a vehicle influences its aerodynamic performance through separation phenomena and flow structure development. Since these flow characteristics have a direct influence on the energy efficiency, safety and comfort, it is essential to study their formation and evolution into the freestream. READ MORE

7. 5. Seeing the invisible: Evolution of wing interference patterns in Hymenoptera, and their application in taxonomy

   Author : Ekaterina Shevtsova; Biologiska institutionen; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Chalcidoidea; parasitic wasps; structural colors; visual signaling; cryptic species; sexual dimorphism; wing membrane thickness; wing micro-morphology; wing cuticle ultrastructure;

   Abstract : The remarkably thin transparent wing membranes in tiny wasps may appear to have a simple structural design, but hide a largely unexplored complex of micro-morphological features that serve aerodynamics and may also function in visual signaling. I found that when such small transparent wings are viewed against a dark background they display vivid structural color patterns due to thin film interference, and named them Wing Interference Patterns (WIPs). READ MORE