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Ultrasonic measurements and modelling of attenuation and phase velocity in pulp suspensions
Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
2005 (English)In: 2005 IEEE Ultrasonics Symposium: 18 - 21 September 2005, Rotterdam, the Netherlands, Piscataway, NJ: IEEE Communications Society, 2005, Vol. 2, 775-779 p.Conference paper (Refereed)
Abstract [en]

In the manufacturing process of paper the mass fraction and material properties of the fibres in the pulp suspension are important for the quality of the finished product. This study presents two different methods of pulp characterisation. The first is based on phase velocity, which we use to investigate the composition of the pulp. Here a method is presented where the optimal number of circular shifts within the sampling window of the signal is determined which gives, in a weakly dispersive medium, a continuous phase spectrum and minimizes the likelihood of discontinuities within the bandwidth. Hence, the ambiguity in phase unwrapping is avoided. The results from phase velocity measurements show that the phase velocity weakly increases with increasing amount of fines in the suspension. The dispersion is caused by the fibres and it correlates with fibre mass fraction. The second method is based on attenuation and is used to characterise the wood fibres. The results of the attenuation experiments show that it is possible to inversely calculate wood fibre properties by fitting the model to the experimental data, if the fibre diameter distribution is known. However, the accuracy of these calculation is difficult to determined and more work in this area is required.

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2005. Vol. 2, 775-779 p.
, I E E E International Ultrasonics Symposium. Proceedings, ISSN 1051-0117
Research subject
Industrial Electronics
URN: urn:nbn:se:ltu:diva-29318DOI: 10.1109/ULTSYM.2005.1602966ScopusID: 33846311820Local ID: 2c19b5a0-5479-11db-9592-000ea68e967bISBN: 0-7803-9382-1OAI: diva2:1002541
IEEE Ultrasonics Symposium : 18/09/2005 - 21/09/2005
Validerad; 2005; 20060913 (ysko)Available from: 2016-09-30 Created: 2016-09-30Bibliographically approved

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Niemi, JanAitomäki, YvonneLöfqvist, Torbjörn
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