Vindkraft i skog

Abstract Not Provided. / Thesis / Bachelor of Science (BSc)

No description available.

Für die Durchführung von Schallausbreitungsmessungen sind Angaben über das vertikale Profil der Temperatur und der Strömungsgeschwindigkeit erforderlich. Hierzu wurden Temperaturmeßfühler mit einfachem Strahlungsschutz entwickelt und zusammen mit Schalenanemometern an einem Meßmast befestigt. Ein Datenlogger speichert aller Minute die Meßwerte der Temperatur und der Windgeschwindigkeit aus 6 Meßhöhen. / For sound propagation measurements ofthe temperature and wind profiles are needed. Therefore thermometers were developed with simple radiation shield and mounted together with cupanemometers at a mast. A datalogger sampled minutely the values of temperature and windspeed in 6 levels.

Wind resource assessment studies have been conducted in the Israeli side and the Palestinian side before; however, the previous studies were restricted with the political border either Palestinian or Israeli except one of them that was based on measurements dated to 1940-1983 (R. Shabbaneh & A. Hasan, 1997). Moreover, the studies were performed years ago, with simple techniques and based on old data (R. Shabbaneh & A. Hasan, 1997). Hence, the needs for a new study that is based on updated data, and using updated model is highly demanded. This study is intended to perform wind resource assessment in Palestine/Israel; the study has used two stages of assessment, primary one based on reference station data on both sides, Israeli and Palestinian. The second stage of wind resource assessment is based on WindPRO software. The wind resource assessment ends up with identifying sites with higher potential that are situated in four selected sites, North of Palestine/Israel, North of West-bank, Jerusalem, and Eilat, the higher potential was in Eilat area bearing mean wind speed of 9.88m/s at 100 m hub height.Moreover, the study recognized the importance of political situation assessment due to the Israeli-Palestinian conflict. Based on conducted survey, the political situation assessment concluded that international non-governmental organizations seem to be most capable of starting up wind power project in Palestine/Israel. Furthermore, the study concluded that supportive policies from both the Israeli and Palestinian governments are crucial to promote wind power projects in the region.

No description available.

The VAD Wind Profile (VWP), a time-height display of winds computed by the National Weather Service's WSR-88D radar, is known on occasion to have errors at night during the fall and spring seasons. Several studies, such Haro and Gauthreaux (1998), confirm that migrating birds often contaminate the VWP output. By means of telescopic observations of a full moon, birds were observed flying on two nights when VWP contamination was suspected. The nature of the VWP errors is consistent with migrating birds due to the seasonality, nocturnal nature, and the magnitude of the errors found (greater than 10 knots). With careful selection of data, two clusters of points on the Velocity-Azimuth Display (VAD) are found to exist at certain altitudes when birds begin migrating. One cluster of points is due to radar sample volumes containing birds, and the other cluster is from radar sample volumes without birds. Being able to determine which cluster represents the wind could allow the wind to be calculated by the VWP. Present limitations with the Radar Product Generator's processor and memory prohibit a very advanced detection algorithm. Two simple objective techniques to determine the existence of the two clusters, and determine the wind, were tested. While they show some promise, these methods require further operational testing to determine their usefulness for real-time warning of bird contamination and the reporting of the true wind.

Für die Durchführung von Schallausbreitungsmessungen sind Angaben über das vertikale Profil der Temperatur und der Strömungsgeschwindigkeit erforderlich. Hierzu wurden Temperaturmeßfühler mit einfachem Strahlungsschutz entwickelt und zusammen mit Schalenanemometern an einem Meßmast befestigt. Ein Datenlogger speichert aller Minute die Meßwerte der Temperatur und der Windgeschwindigkeit aus 6 Meßhöhen. / For sound propagation measurements ofthe temperature and wind profiles are needed. Therefore thermometers were developed with simple radiation shield and mounted together with cupanemometers at a mast. A datalogger sampled minutely the values of temperature and windspeed in 6 levels.

Wind power is seen as one of the most effective means available to combat the twin crises of global climate change and energy security. The annual market growth has established wind power as the leading renewable energy technology. Due to the availability of sparsely populated and flat open terrain, the Yucatán Peninsula located in eastern México is a promising region from the perspective of wind energy development but no comprehensive assessment of wind resource has been previously published. A basic requirement when developing wind power projects is to study the main characteristic parameters of wind in relation to its geographical and temporal distribution. The analysis of diurnal and seasonal wind patterns are an important stage in the move towards commercial exploitation of wind power. The research developed during the PhD has comprehensively assessed the wind behaviour over the Yucatán Peninsula region covering long term patterns at three sites, a spatial study using short term data for nine sites, a vertical profile study on one inland site and an offshore study made on a pier at 6.65km from the North shore. Monthly trends, directional behaviours and frequency distributions were identified and discussed. The characteristics of the wind speed variation reflected their proximity to the coast and whether they were influenced by wind coming predominantly from over the land or predominantly from over the sea. The atmospheric stability over the eastern seas was also analysed to assess thermal effects for different wind directions. Diurnal wind speed variations are shown to be affected in particular by the differing wind conditions associated with fetches over two distinct offshore regions. Seasonal behaviour suggests some departure from the oscillations expected from temperature variation. The offshore wind is thermally driven suggesting largely unstable conditions and the potential development of a shallow Stable Internal Boundary Layer.

<p>A new theory for predicting the windprofile over a canopy has been evaluated. The theory was first presented by Harman and Finnigan (2007). The theory relies on the forming of a mixing-layer above the canopy, due to different mean wind in and above the canopy. Characteristics from both mixing-layer and Monin Obukhov similarity theory have been used to develop the governingequations that give the wind profile. The theory has been used to calculate wind profiles for sixdifferent atmospheric stabilities. In order to evaluate the theory, profiles from the theory have beencompared to measurements from Jädraås forest, Sweden. Profiles from Monin Obukhov similarity theory were also used for comparison.In general the mixing-layer theory gives better results than Monin Obukhov similarity theory. Agreement with measurements is good in neutral conditions, but fails when the atmospheric stability is altered, especially in convective conditions. This is believed to be due to the canopy lacking in thickness. The mean wind speed is systematically underestimated and this is also believed to be caused by insufficient thickness of the canopy. A correction for this behaviour is proposed. The theory gives higher values of the mean wind speed in convective conditions with the correction and the calculated values of mean wind speed are closer to the measurements.</p>