Selvstændig forsker

Portræt af Anders Borgens karriereforløb som økologisk forsker

Monokulturer bør afløses af større diversitet i afgrøderne

Portræt af Anders Borgen og arbejdet for afgrødediversitet

Historical review of C-5A lift distribution control systems

Analytical and experimental development work on various load alleviation systems for the C-5A is reviewed to trace the development of the technical and hardware concepts to the present time. Variations in system objectives, means of implementation and effects on loads and airplane performance, stability and control are discussed

Soft-Bottom Ecological Status and Distribution of Leptosynapta sp. in Kviturspollen

This thesis aims to give an overview of the current ecological status of Kviturspollen by using CTD data and soft-bottom samples to evaluate the conditions, and results from past surveys to evaluate any improvement or deterioration. Kviturspollen is a land-locked fjord located approximately 14 km south of Bergen, and has been a part of the local recipient surveys in 1990, 2013 and 2014. Due to a shallow sill between Raunefjorden and Kviturspollen, as well as a canal which changed the main current from the neighboring land-locked fjord away from Kviturspollen, the oxygen levels through time have been very low and periodically absent. Kviturspollen is a land-locked fjord with two eelgrass meadows, and therefore has a unique and important ecosystem to preserve. In this survey, eight stations were chosen in Kviturspollen and one was chosen in Raunefjorden for reference. CTD-measurements were taken in three main areas: the innermost and the outer part of Kviturspollen, as well as in Raunefjorden. All samples were collected between May 2021, and February 2022. At some of the stations, additional samples were taken to more accurately map the distribution and density of the holothurian Leptosynapta sp. Comparing results from past surveys with the results from this, shows that Kviturspollen has undergone slight improvements in relations to diversity and sensitivity of the species. The salinity levels in the land-locked fjord were good, and the oxygen levels were high throughout all out measurements, although the sediment in some of the stations contained H2S. The bottom fauna samples presented great variations in diversity and sensitivity between the stations, and nearby stations often showed low similarity. In Kviturspollen, the diversity and sensitivity were highest at station 3 and 6, probably because of low amounts of sedimentation and high exposure to the current. Station 1 and 2 were completely lifeless, with sediment smelling of H2S. This is likely because the previous surveys have shown that the bottom water in the deepest basins frequently have been anoxic in the past. The stations are also located outside the current in an area with high sedimentation. The density of L. sp. was highest in the areas with high sedimentation and no H2S. The ecological status of Kviturspollen appears to have improved slightly, with a higher number of individuals found per m2, higher NQI1 values, and no anoxic bottom water measured.Masteroppgave i biologiBIO399KMAMN-BI

Three 10W C-band Power Amplifier Alternatives for use in TT&C-Transmitters

This thesis describes the first stage in designing and realizing three 10W C-band power amplifier alternatives based on the GaN-technology for use in Kongsberg Norspace future TT&C-transmitters. The operational frequency range spanned from 3.4GHz to 4.25GHz. It was decided to build one single-stage amplifier based on the 10W CGH40010F transistor from Cree and two dual-stage amplifiers with a balanced second stage based on the 6W CGH40006P transistor, from the same manufacturer. AWilkinson power divider was used to feed each branch in the second stage. In the design procedure, source and load pull simulations were performed in order to retrieve the optimal impedances for each transistor and as a basis for the design of the matching networks. By utilizing a looping method in the design process of the matching networks, it was possible to obtain results that, to some extent, fulfilled the requirements. Simulations and design were carried out in ADS by Keysight (former Agilent). The simulated results showed that all three designs were capable of delivering 10W output power throughout the frequency band. The single-stage amplifier obtained a simulated power added efficiency (PAE) above 45% at 40dBm output power, while the two dual-stage designs achieved a PAE between 41-44% and 34-36%, respectively. S-parameter simulations reviled that the single-stage design accomplished a small signal gain of 11.3dB-11.7dB, while the input reflection coefficients varied between -3dB and -5dB. To achieve the requirement of having the input reflection coefficients less than -10dB, the dual-stage designs utilized an attenuator with 1.5dB loss at the input match, both designs obtained a small signal gain above 20dB. Like the simulated results, the large signal measurements showed that the amplifiers were capable of delivering 10W output power, except the single-stage design at 4.0375GHz (which were one of the test frequencies). The measured power added efficiency for the single-stage amplifier varied between 27%-44%, while the two dual-stage amplifiers obtained a PAE between 39-43% and 35-42%, respectively. This implied that non of the designs managed to fulfill the requirement of having a total power consumption less than 25W over the specified frequency range. A simulated large signal stability analysis were performed on each design and the results revealed that one of the dual-stage designs had a potential instability around 790MHz, and practical spectrum measurements confirmed frequency components at 750MHz, 1.51GHz and 2.25GHz. However, the spurious frequency components had no measurable impact on the performance. A small section presenting the future prospects in terms of utilizing the GaN-technology in Space and suggestions for future work, have also been included. The thesis concluded that several iterations must be done before an integration with the transmitter can be made

Soft-Bottom Ecological Status and Distribution of Leptosynapta sp. in Kviturspollen

This thesis aims to give an overview of the current ecological status of Kviturspollen by using CTD data and soft-bottom samples to evaluate the conditions, and results from past surveys to evaluate any improvement or deterioration. Kviturspollen is a land-locked fjord located approximately 14 km south of Bergen, and has been a part of the local recipient surveys in 1990, 2013 and 2014. Due to a shallow sill between Raunefjorden and Kviturspollen, as well as a canal which changed the main current from the neighboring land-locked fjord away from Kviturspollen, the oxygen levels through time have been very low and periodically absent. Kviturspollen is a land-locked fjord with two eelgrass meadows, and therefore has a unique and important ecosystem to preserve. In this survey, eight stations were chosen in Kviturspollen and one was chosen in Raunefjorden for reference. CTD-measurements were taken in three main areas: the innermost and the outer part of Kviturspollen, as well as in Raunefjorden. All samples were collected between May 2021, and February 2022. At some of the stations, additional samples were taken to more accurately map the distribution and density of the holothurian Leptosynapta sp. Comparing results from past surveys with the results from this, shows that Kviturspollen has undergone slight improvements in relations to diversity and sensitivity of the species. The salinity levels in the land-locked fjord were good, and the oxygen levels were high throughout all out measurements, although the sediment in some of the stations contained H2S. The bottom fauna samples presented great variations in diversity and sensitivity between the stations, and nearby stations often showed low similarity. In Kviturspollen, the diversity and sensitivity were highest at station 3 and 6, probably because of low amounts of sedimentation and high exposure to the current. Station 1 and 2 were completely lifeless, with sediment smelling of H2S. This is likely because the previous surveys have shown that the bottom water in the deepest basins frequently have been anoxic in the past. The stations are also located outside the current in an area with high sedimentation. The density of L. sp. was highest in the areas with high sedimentation and no H2S. The ecological status of Kviturspollen appears to have improved slightly, with a higher number of individuals found per m2, higher NQI1 values, and no anoxic bottom water measured