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Luis Cristovao, Sarah Rönnberg and Erik Johansson

Wall of Fame at LTU in Skellefteå extended with three graduate portraits

Published: 20 December 2013

The final nailing ceremony of 2013 at LTU i Skellefteå is now completed. One licentiate and two PhD at LTU in Skellefteå presented their theses in front of a big audience in the Forum building. Since the tradition started on 15 May 2012, 15 doctoral and licentiate theses has been nailed.


The LTU choir sang the traditional anthem and Ingrid Thylin, Development Manager at Skellefteå municipality informed about the nailing tradition. She presented the researchers from Luleå University of Technology in Skellefteå, Erik Johansson, Sarah Rönnberg and Luis Cristovao who all shortly presented their research.

Erik Johansson, Wood Technology, LTU in Skellefteå, presented his licentiate thesis "Computed tomography of sawlogs: Knot detection and sawing optimization". Erik informed about the possibility of locating knots in logs, how these automatically can be detected by X-ray and how the information can be used to optimize the decomposition process in sawmills. This is highly relevant as the use of industrial computed tomography (CT scan) has commenced at sawmills.

Luis Cristovao, Wood Technology, LTU in Skellefteå, nailed his thesis "Machining Properties of Wood: Tool wear, cutting force and tensioning of blades". The research is focused on wood machining. The main objective was to increase knowledge of machining properties of some Mozambican and Swedish wood species with a focus on tool wear, cutting force and power consumption. Another objective was to improve dynamic stability of saw blades by using different methods of monitoring flatness, tensioning and levelling.

Sarah Rönnberg, Electric Power Engineering, LTU in Skellefteå, nailed her doctoral thesis "Emission and interaction from domestic installations in the low-voltage electricity network, up to 150 kHz". The thesis is focused on waveform distortion when introducing photovoltaic and LED-lamps in the low voltage network. It is shown that the increase in amplitude for frequency components below 2 kHz becomes lower than expected. However, new phenomenon will occur for frequency components in the range between 2 kHz and 150 kHz. Moreover, new knowledge regarding interaction between low voltage equipment and power line communication has been gained. 

Erik Johansson och Ingrid Thylin