Improved Methods for GPS Navigation

This Master's Thesis presents the development of methods for improved GPS navigation on Wayfinder Navigator, a mobile phone based navigation system developed by Wayfinder Systems. Focus has been put on off track detection, i.e. to detect a user diverging from the route given by the navigation system, and how the GPS position is presented to the user by the application. Improving off track detection includes both lowering the detection time and simultaneously maintaining robustness in order to avoid false alarms due to different types of error sources

Solar Wind Variations Related to Fluctuations of the North Atlantic Oscillation

A study on a possible solar wind interaction with the North AtlanticOscillation (NAO) is performed. Results are presented suggesting arelationship between the NAO index and the electric field strength E ofthe solar wind. A possible scenario for the suggested interaction isthat an electromagnetic disturbance is generated by the solar wind inthe global electric circuit of the ionosphere. This disturbance is thendynamically propagating downward through the atmosphere and subsequentlyinfluencing the large-scale pressure system in the North Atlanticregion. A relationship is also evident on longer time-scales when usingthe group sunspot number as a proxy for the solar wind. (Art. No. 1718

Solar mean magnetic field variability: A wavelet approach to Wilcox Solar Observatory and SOHO/Michelson Doppler Imager observations

Solar mean magnetic field (SMMF) measurements from the Wilcox Solar Observatory and with the SOHO/MDI instrument are described and analyzed. Even though two completely different methods of observation are used, the two data sets obtained show a strong similarity. Using continuous wavelet transforms, SMMF variability is found at a number of temporal scales. Detected SMMF signals with a 1–2 year period are considered to be linked to variations in the internal rotation of the Sun. Intermediate SMMF oscillations with a period of 80–200 days are probably connected to the evolution of large active regions. We also find evidence for 90 min variations with coronal mass ejections as a suggested origin

A neural network-based local model for prediction of geomagnetic disturbances

This study shows how locally observed geomagnetic disturbances can bepredicted from solar wind data with artificial neural network (ANN)techniques. After subtraction of a secularly varying base level, thehorizontal components XSq and YSq of the quiettime daily variations are modeled with radial basis function networkstaking into account seasonal and solar activity modulations. Theremaining horizontal disturbance components DeltaX and DeltaY aremodeled with gated time delay networks taking local time and solar winddata as input. The observed geomagnetic field is not used as input tothe networks, which thus constitute explicit nonlinear mappings from thesolar wind to the locally observed geomagnetic disturbances. The ANNsare applied to data from Sodankylä Geomagnetic Observatory locatednear the peak of the auroral zone. It is shown that 73% of the DeltaXvariance, but only 34% of the DeltaY variance, is predicted from asequence of solar wind data. The corresponding results for prediction ofall transient variations XSq+DeltaX andYSq+DeltaY are 74% and 51%, respectively. The local timemodulations of the prediction accuracies are shown, and the qualitativeagreement between observed and predicted values are discussed. If drivenby real-time data measured upstream in the solar wind, the ANNs heredeveloped can be used for short-term forecasting of the locally observedgeomagnetic activity

Upgrading of circuit diagrams in a HVDC-station

Detta examensarbete är gjort på uppdrag av ABB i Ludvika. ABB har fått en beställning på en uppgradering av en högspänd likströmstation, på engelska High Voltage Direct Current (HVDC). Det finns huvudsakligen två olika tekniker gällande HVDC. Det är HVDC med Line Commutated Converters (LCC) och HVDC med Voltage Source Converters (VSC). LCC-tekniken är den äldsta och mest använda tekniken och är den teknik som stationen som uppgraderas använder. VSC-HVDC är en något nyare teknik som har fördelen att den inte kräver ett genererande nät på båda sidor av HVDC-länken men nackdelen att den inte klarar av lika höga effekter som LCC gör. Den har med dessa egenskaper blivit en populär teknik att använda för att till exempel överföra energi från vindkraftsparker ute till havs in till fastlandet eller för att förse oljeplattformar med energi. VSC-tekniken introducerades för första gången 1997 av ABB där den går under namnet HVDC-Light. Den aktuella HVDC-länken är en förbindelse mellan två länder och har en överföringskapacitet på totalt 600 MW. Uppgraderingen innefattar även uppdatering av befintliga scheman för att de skall finnas tillgängliga i den nya programvaran Engineering Base. Ritningarna har ritats i Microsoft Visio. Den utrustning som har ritats om och behandlas i denna rapport gäller utrustningen på likströmssidan av HVDC-stationen. Det innefattar jordknivar, frånskiljare, strömtransformatorer, spänningsdelare, överströmsskydd och genomföringar.This thesis was conducted on behalf of ABB in Ludvika. ABB has received an order for an upgrade of a high voltage direct current (HVDC) station. There are two main technologies that HVDC is based on; line commutated converters (LCC) and voltage source converters (VSC). The LCC technology is the oldest and most widely used. It's also the technology that the upgraded station is based on. VSC HVDC is a newer technology that has the advantage of not requiring a generating power grid on both sides of the HVDC link but has the disadvantage that it cannot handle as high power as LCC can. With these qualities it has become a popular technology to use to transfer energy from offshore wind farms to the mainland or to provide oil platforms with energy. VSC technology was first introduced in 1997 by ABB where it is called HVDC Light. The revised HVDC link is a connection between two countries and has a total power transmission of 600 MW. The upgrade also includes updating existing circuit diagrams for the HVDC station to be available in the new software Engineering Base. The circuit diagrams have been drawn in Microsoft Visio. The equipment which have been designed and examined in this report applies to equipment on the DC side of the HVDC station. This includes grounding knives, disconnectors, power transformers, voltage dividers, current protection units and wall bushings

Solar wind electric field modulation of the NAO: A correlation analysis in the lower atmosphere

Using geopotential height data we find a strong correlation between theelectric field strength E of the solar wind and pressure variations inthe stratosphere and troposphere. The large-scale evolution of E seemsto influence the stratospheric pressure in both hemispheres with theexception of the polar regions. For the tropospheric pressure theinfluence is concentrated to an area in the northern Atlantic. Usingpressure and temperature data at sea level, we conclude that thecorrelation with E resembles the action of the North AtlanticOscillation with an area with negative pressure correlation in theArctic, an area with positive pressure correlation in the subtropics, anarea with negative temperature correlation over Greenland and northeastCanada, and an area with positive temperature correlation over Europe

A wavelet analysis of solar mean magnetic field measurements

Solar mean magnetic field (SMMF) measurements from the Wilcox SolarObservatory and with SOHO/MDI are analyzed using continuous wavelettransforms, SMMF variability is found at a number of temporal scales.Detected SMMF variations with a 1-2 year period is considered to belinked to long-term variations in the internal rotation of the Sun.Intermediate SMMF oscillations with a period of 80-200 days are probablyconnected to the evolution of large active regions. We also findevidence for 90 minute variations with coronal mass ejections as aprobable origin

Upgrading of circuit diagrams in a HVDC-station

Detta examensarbete är gjort på uppdrag av ABB i Ludvika. ABB har fått en beställning på en uppgradering av en högspänd likströmstation, på engelska High Voltage Direct Current (HVDC). Det finns huvudsakligen två olika tekniker gällande HVDC. Det är HVDC med Line Commutated Converters (LCC) och HVDC med Voltage Source Converters (VSC). LCC-tekniken är den äldsta och mest använda tekniken och är den teknik som stationen som uppgraderas använder. VSC-HVDC är en något nyare teknik som har fördelen att den inte kräver ett genererande nät på båda sidor av HVDC-länken men nackdelen att den inte klarar av lika höga effekter som LCC gör. Den har med dessa egenskaper blivit en populär teknik att använda för att till exempel överföra energi från vindkraftsparker ute till havs in till fastlandet eller för att förse oljeplattformar med energi. VSC-tekniken introducerades för första gången 1997 av ABB där den går under namnet HVDC-Light. Den aktuella HVDC-länken är en förbindelse mellan två länder och har en överföringskapacitet på totalt 600 MW. Uppgraderingen innefattar även uppdatering av befintliga scheman för att de skall finnas tillgängliga i den nya programvaran Engineering Base. Ritningarna har ritats i Microsoft Visio. Den utrustning som har ritats om och behandlas i denna rapport gäller utrustningen på likströmssidan av HVDC-stationen. Det innefattar jordknivar, frånskiljare, strömtransformatorer, spänningsdelare, överströmsskydd och genomföringar.This thesis was conducted on behalf of ABB in Ludvika. ABB has received an order for an upgrade of a high voltage direct current (HVDC) station. There are two main technologies that HVDC is based on; line commutated converters (LCC) and voltage source converters (VSC). The LCC technology is the oldest and most widely used. It's also the technology that the upgraded station is based on. VSC HVDC is a newer technology that has the advantage of not requiring a generating power grid on both sides of the HVDC link but has the disadvantage that it cannot handle as high power as LCC can. With these qualities it has become a popular technology to use to transfer energy from offshore wind farms to the mainland or to provide oil platforms with energy. VSC technology was first introduced in 1997 by ABB where it is called HVDC Light. The revised HVDC link is a connection between two countries and has a total power transmission of 600 MW. The upgrade also includes updating existing circuit diagrams for the HVDC station to be available in the new software Engineering Base. The circuit diagrams have been drawn in Microsoft Visio. The equipment which have been designed and examined in this report applies to equipment on the DC side of the HVDC station. This includes grounding knives, disconnectors, power transformers, voltage dividers, current protection units and wall bushings