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Non-Invasive Multidimensional Imaging Applied on Biological Substances
Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
2002 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents the research and development of a microwave in-strument to capture tomographic information from the inner structure ofthe biological sample. The principle of the instrument is based on theanisotropy introduced by the fibres in materials such as wood and musclesin terms of information regarding changes in the fibre structure. The in-formation is presented as images representing the state of polarization us-ing Stokes parameters, the complex polarization ratio, and the ellipticityand the linear tilt angles. The theory of wave propagation in anisotropicmedia is discussed and related to the dielectric properties of wood. Ex-periments have shown that the developed instrument can be utilized invarious applications such as localizing knots and cavities in wood andto detect mechanical contamination of meat. A second instrument hasbeen improved by introducing a new signal analysis step to estimate therelative shrinkage profile of paper. The estimator is based on trackingfrequency variations in the joint time frequency spectrum and follows thelower bound of the problem for the relevant noise levels.

Place, publisher, year, edition, pages
Göteborg: Chalmers university of technology , 2002. , p. 154
Series
Doktorsavhandlingar vid Chalmers Tekniska Högskola, Ny serie, ISSN 0346-718X ; 1886
Keywords [en]
Microwave propagation, Tomography, Polarimetry, Frequency estimation, Anisotropic media, Wood, Muscles, Paper
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:hh:diva-2461Local ID: 2082/2863ISBN: 91-7291-204-9 OAI: oai:DiVA.org:hh-2461DiVA, id: diva2:239679
Public defence
(English)
Note
[Paper A] Kaestner, A.P. & Bååth, L.B., Microwave polarimetry based scanning for internal defects, Submitted to IEEE Transactions on Antennas and Propagation.Available from: 2009-04-16 Created: 2009-04-16 Last updated: 2010-03-12Bibliographically approved
List of papers
1. Microwave polarimetry based wood scanning
Open this publication in new window or tab >>Microwave polarimetry based wood scanning
2000 (English)In: Proceedings of the 12th International Symposium on Nondestructive Testing of Wood: University of Western Hungary, Sopron, 13-15 September 2000, Sopron: University of Western Hungary , 2000, p. 8-Conference paper, Published paper (Other academic)
Abstract [en]

We describe a method to detect knots and faults in wood logs based on microwave measurements and the depolarising properties of wood. The depolarisation is an effect of the anisotropy in the dielectric properties of wood, which is caused by the fibre structure. The measurements are made in the frequency domain where a discrete reflec-tion spectrum is sampled. By transforming the frequency spectrum into the time domain the spatial distribution of the reflections appear. The wave is transmitted in a pure linear polarisation, tilted to 45° For each discrete frequency all available information is measured for the reflected wave and therefore it is possible to calculate the complex polarisation ratio and the state of polarisation which are the quantities containing the most visible information. The measurements are one dimensional and by combining measurements from different directions we create tomographic slice images of the inner structure of a log. Our measurements has showed the possibility to follow the extension of knots in a log using only a iso-surface visualisation. The used equipment is working at low intensity and is therefore virtually harm-less to human beings, furthermore it is portable and can be operated by one single person.

Place, publisher, year, edition, pages
Sopron: University of Western Hungary, 2000
Keywords
Microwave measurements, Wood logs, Image reconstruction, Tomography
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hh:diva-1949 (URN)2082/2344 (Local ID)963-7180-88-5 (ISBN)2082/2344 (Archive number)2082/2344 (OAI)
Conference
12th International Symposium on Nondestructive Testing of Wood, University of Western Hungary, Sopron, 13-15 September, 2000
Available from: 2008-09-23 Created: 2008-09-23 Last updated: 2013-11-15Bibliographically approved
2. Non-destructive methods to detect decay in trees
Open this publication in new window or tab >>Non-destructive methods to detect decay in trees
2004 (English)In: Wood Research, ISSN 1336-4561, Vol. 49, no 2, p. 17-28Article in journal (Refereed) Published
Abstract [en]

The ability to measure the presence of decay in trees using three different methods is studied. The methods are based on drill resistance, sound wave propagation measurements, and microwave polarimetry. All methods have been tested on samples with artificial cavities as well as on decayed samples. The experiments with both types of samples have showed positive results.

Place, publisher, year, edition, pages
Bratislava: State Forest Products Research Institute, 2004
Keywords
Acoustic wave propagation, Density, Energy absorption, Forestry, Microwaves, Nondestructive examination, Polarimeters, Tomography, Wood, Artifical cavities, Degree of decay, Drill resistance, Microwave polarimetry, Organic Decay, Microwaves, Nondestructive Tests, Polarimetry, Sound Waves, Trees, Wood, Wood Decay
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hh:diva-4070 (URN)000222854200003 ()2-s2.0-14644391611 (Scopus ID)
Available from: 2010-03-12 Created: 2010-03-12 Last updated: 2012-06-18Bibliographically approved
3. Estimating the relative shrinkage profile of newsprint
Open this publication in new window or tab >>Estimating the relative shrinkage profile of newsprint
2003 (English)In: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 42, no 5, p. 1467-1475Article in journal (Refereed) Published
Abstract [en]

When water is removed from the paper during paper making, a dimensional change occurs in which the paper shrinks in the direction perpendicular to the direction of processing. The dimensional changes vary across the web and influence, e.g., the surface and compression properties of the paper; they also complicate the control of the paper machine. In this article, a robust method for estimating the relative shrinkage profile is presented. The method is based on a one-dimensional recording of the imprints from the forming fabric, using a fluorescence technique. The recording is transformed into a time-frequency spectrum, on which three different frequency estimators have been evaluated. In simulations on synthetic data and measurements on paper profiles the estimator that maximizes the correlation energy showed the most robust and accurate performance of the methods evaluated, even at a low signal-to-noise ratio.

Place, publisher, year, edition, pages
Redondo Beach, Calif.: SPIE, The International Society for Optical Engineering, 2003
Keywords
Fluorescence, Frequency estimators, Paper shrinkage, Simulations
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hh:diva-216 (URN)10.1117/1.1567260 (DOI)000182985900041 ()2-s2.0-0038380679 (Scopus ID)2082/511 (Local ID)2082/511 (Archive number)2082/511 (OAI)
Available from: 2006-11-24 Created: 2006-11-24 Last updated: 2018-03-23Bibliographically approved

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