Sökning: "tower"

Visar resultat 11 - 15 av 86 avhandlingar innehållade ordet tower.

1. 11. FE modelling of friction connections in tubular tower for wind turbines

   Författare :Marouene Limam; Jean-Francois Demonceau; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Steel Structures; Stålbyggnad;

   Sammanfattning : During the last few decades the demand for renewable energy has led to a myriad of innovative solutions. The present assembling solution between two segments of a tubular tower is accomplished by conventional ring flange connection. This connection suffers from economical and technological barriers. LÄS MER

3. 12. Remote sensing phenology at European northern latitudes - From ground spectral towers to satellites

   Författare :Hongxiao Jin; Institutionen för naturgeografi och ekosystemvetenskap; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Remote sensing; climate sensitivity.; calibration; ground spectral tower; Plant phenology index PPI ; northern latitude;

   Sammanfattning : Plant phenology exerts major influences on carbon, water, and energy exchanges between atmosphere and ecosystems, provides feedbacks to climate, and affects ecosystem functioning and services. Great efforts have been spent in studying plant phenology over the past decades, but there are still large uncertainties and disputations in phenology estimation, trends, and its climate sensitivities. LÄS MER

4. 13. Noise, eigenfrequencies and turbulence behavior of a 200 kW H-rotor vertical axis wind turbine

   Författare :Erik Möllerström; Jonny Hylander; Fredric Ottermo; Hans Bernhoff; Göran Sidén; Mats Åbom; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; VAWT; H-rotor; eigenfrequency; semi-guy-wired tower; noise emission; sound power level; microphone array; turbulence intensity; power curve; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Sammanfattning : Vertical-axis wind turbines (VAWTs) have with time been outrivaled by the today more common and economically feasible horizontal-axis wind turbines (HAWTs). However, VAWTs have several advantages which still make them interesting, for example, the VAWTs can have the drive train at ground level and it has been argued that they have lower noise emission. LÄS MER

5. 14. Resistance of polygonal cross-sections : application on steel towers for wind turbines

   Författare :Olga Garzon; Carlos Alberto da Silva Rebelo; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Steel Structures; Stålbyggnad;

   Sammanfattning : Wind power is considered an efficient alternative for production of electrical energy. One advantage that wind power offers compared to conventional ways of producing energy such as fossil energy and nuclear energy is the low emission of carbon dioxide “CO2” during production of electrical energy. LÄS MER

7. 15. Behaviour of pretensioned bolts in friction connections : towards the use of higher strength steels in wind towers

   Författare :Christine Heistermann; Carlos Rebelo; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Steel Structures; Stålbyggnad; Centrumbildning - Centrum för högpresterande stål CHS ; Centre - Centre for High Performance Steel CHS ;

   Sammanfattning : During recent years wind energy has established as an alternative to commonenergy sources. To advance its competitiveness, the costs for the constructionof a wind tower have to be reduced. One possible option is the use of frictiongrip joints instead of flange connections to join various tower segments in atubular steel tower. LÄS MER