Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Online fibre property measurements: foundations for a method based on ultrasound attenuation
Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.ORCID-id: 0000-0002-2388-3358
2009 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis presents the foundations of a method for estimating fibre properties of pulp suitable for online application in the pulp and paper industry. In the pulp and paper industry, increased efficiency and greater paper quality control are two of the industry's main objectives. It is proposed that online fibre property measurements are a means of achieving progress in both of these objectives. Optical based systems that provide valuable geometric data on the fibres and other pulp characteristics are commercially available. However, measurements of the elastic properties of the fibres are not currently implemented using these systems. To fill this gap an ultrasound based system for measuring the elastic properties of the wood fibres in pulp is proposed. Ultrasound propagation depends on the elastic properties of a solid. Hence attenuation measurements from suspensions of fibres depend on their elastic properties. The method is based on solving the inverse problem where the output is known and the objective is to establish the inputs. In this case, attenuation is measured and a model of attenuation based on ultrasound scattering is developed. A search algorithm is used for finding elastic properties that minimize the error between the model and measured attenuation. The results of the search are estimates of the elastic properties of the fibres in suspension. The results show resonance peaks in the attenuation, in the frequency region tested, for fibres with radii of the order of 10 microns. These peaks are found in both the measured and modelled attenuation spectra. Further investigation of these resonances suggests that they are due to modes of vibration in the fibre where the fibre modelled as an infinitely long cylinder. These resonances are shown to aid in the identification of the elastic properties. The attenuation is found to depend heavily on the geometry of the fibres. Hence fibre geometry, which can be obtained from online optical fibre measurement system, provides the key to extracting the elastic properties from the attenuation signal. Studies are also carried out on the effect of viscosity on attenuation as well as the differences in attenuation between hollow and solid synthetic fibres in suspensions. The measurement method is also applied to hardwood and softwood Kraft pulps. The results of these studies show that using the model derived in the thesis and attenuation measurements, estimates of the elastic properties can be obtained. The elastic property estimates for synthetic fibres agree well with values from other methods. The elastic property estimates for pulps require further validation due to the difficulty in comparing between different testing methods and different types of pulp. The conclusions, based on the work so far and under three realisable conditions, are that the shear modulus and the transverse Young's modulus of pulp fibres can be measured. Once these conditions are met a system based on this method can be implemented. By doing this the industry would benefit from the increase in paper quality control and energy saving such system could provide.

Ort, förlag, år, upplaga, sidor
Luleå: Luleå tekniska universitet, 2009. , s. 178
Serie
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Nationell ämneskategori
Annan elektroteknik och elektronik
Forskningsämne
Industriell elektronik
Identifikatorer
URN: urn:nbn:se:ltu:diva-26500Lokalt ID: e8ca57c0-3ab5-11de-a8ec-000ea68e967bISBN: 978-91-86233-54-9 (tryckt)OAI: oai:DiVA.org:ltu-26500DiVA, id: diva2:999663
Anmärkning

Godkänd; 2009; 20090507 (aitomaki); DISPUTATION Ämnesområde: Industriell elektronik/Industrial Electronics Opponent: Professor Richard Challis, the University of Nottingham, United Kingdom Ordförande: Teknologie doktor Torbjörn Löfqvist, Luleå tekniska universitet Tid: Onsdag den 3 juni 2009, kl 10.00 Plats: D770, Luleå tekniska universitet

Tillgänglig från: 2016-09-30 Skapad: 2016-09-30 Senast uppdaterad: 2018-02-27Bibliografiskt granskad

Open Access i DiVA

fulltext(6704 kB)73 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 6704 kBChecksumma SHA-512
581a95216f5e68c268172a0f1b61aa3940a0584f2fa89f601a392e717848706ebd7ac8b299429c212d20917a9170a3bbaff607d7d1e5d1a39072bd56c5fcbbf6
Typ fulltextMimetyp application/pdf

Personposter BETA

Aitomäki, Yvonne

Sök vidare i DiVA

Av författaren/redaktören
Aitomäki, Yvonne
Av organisationen
EISLAB
Annan elektroteknik och elektronik

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 73 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

isbn
urn-nbn

Altmetricpoäng

isbn
urn-nbn
Totalt: 204 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf