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Numerical Performance of Stability Enhancing and Speed Increasing Steps in Radiative Transfer Solution Methods
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik. (DPC - Digital printing center)ORCID-id: 0000-0002-0529-1009
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2009 (Engelska)Ingår i: Journal of Computational and Applied Mathematics, ISSN 0377-0427, E-ISSN 1879-1778, Vol. 228, nr 1, s. 104-114Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Methods for solving the radiative transfer problem, which are crucial for a number of sectors of industry, involve several numerical challenges. DORT2002 is a fast and numerically stable solution method for this problem, and has been implemented in MATLAB. This paper studies the numerical performance of DORT2002, in terms of stability, speed and accuracy. Focus is on the effects of the steps that are needed to make the method numerically efficient, and that differ from a naive implementation. Performance tests show that the steps that are included to improve stability and speed of DORT2002 are very successful. Together they give an unconditionally stable solution method to a problem previously considered numerically intractable, and decrease computation time compared to a naive implementation with a factor 1 000-10 000 in typical cases and with a factor up to and beyond 10 000 000 in extreme cases. It is also shown that the speed increasing steps are not introduced at the cost of reduced accuracy. Further studies and developments, that can have a positive impact on computation time, are suggested.

Ort, förlag, år, upplaga, sidor
2009. Vol. 228, nr 1, s. 104-114
Nyckelord [en]
radiative transfer, solution method, numerical performance, stability, speed, accuracy
Nationell ämneskategori
Matematik
Identifikatorer
URN: urn:nbn:se:miun:diva-2799DOI: 10.1016/j.cam.2008.08.045ISI: 000265892700011Scopus ID: 2-s2.0-63349094792Lokalt ID: 2322OAI: oai:DiVA.org:miun-2799DiVA, id: diva2:27831
Tillgänglig från: 2008-09-30 Skapad: 2009-01-19 Senast uppdaterad: 2017-12-12Bibliografiskt granskad
Ingår i avhandling
1. Mathematical modeling and numerical tools for simulation and design of light scattering in paper and print
Öppna denna publikation i ny flik eller fönster >>Mathematical modeling and numerical tools for simulation and design of light scattering in paper and print
2007 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This work starts with a real industrial problem - the perceived need for a moredetailed and more accurate model for light scattering in paper and print than theKubelka‐Munk model of today. A careful analysis transfers this problem into aphysical description of the phenomena involved. This is then given a mathematicalformulation, and a detailed analysis leads to numerical solution procedures forspecific sub problems. Methods from scientific computing make it possible to meetindustrial demands made on speed and stability, and implementation in computercode is then followed by analysis of accuracy and stability.A problem formulation and a solution method are outlined for the forwardradiative transfer problem. First, all necessary steps to arrive at a numericallystable solution procedure are treated, and then methods are introduced to increasethe speed by a factor of several thousands or millions compared to a naiveapproach. The method is shown to be unconditionally stable, though the problemwas previously considered numerically intractable, and systematic studies ofnumerical performance are presented.The inverse radiative transfer problem is given a least‐squares formulation, anddifferent solution methods are analyzed and compared. Specifically, a two‐phasemethod for estimation of the scattering and absorption coefficients and theasymmetry factor (σs, σa and g) is presented. A sensitivity analysis is given, and it isshown how it can be used for designing measurements with minimal impact frommeasurement noise.It is shown how the standardized use of Kubelka‐Munk and the d/0°instrument leads to errors, and that the errors arising from an over‐idealized viewof the instrument - due to the fact that instrument readings are incorrectlyinterpreted - can be larger than any errors inherent in the Kubelka‐Munk modelitself. It is argued that the measurement device and the simulation model cannot beviewed as separate instances, which is a widespread implicit practice in appliedreflectance measurements. Rather, given a measurement device, measurement datashould be interpreted through a model that takes into consideration the actualgeometry, function and calibration of the instrument.The resulting tool, DORT2002, is in all aspects the Next Generation Kubelka‐Munk, and provides a greater range of applicability, higher accuracy and increasedunderstanding. It offers better interpretation of measurement data, and facilitatesthe exchange of data between the paper and graphical arts industries. It opens forunderstanding of anisotropic reflectance and for the utilization of the asymmetryfactor to design anisotropy, and thereby for the design of different visualappearance or optical performance in new printed or paper products.

Ort, förlag, år, upplaga, sidor
Sundsvall: Mittuniversitetet, 2007. s. 32
Serie
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 22
Nyckelord
mathematical modeling, radiative transfer, integro-differential equations, inverse problems, parameter estimation, solution method, numerical performance, light scattering, paper industry applications, Kubelka-Munk
Nationell ämneskategori
Matematik
Identifikatorer
urn:nbn:se:miun:diva-5908 (URN)5026 (Lokalt ID)978-91-85317-50-9 (ISBN)5026 (Arkivnummer)5026 (OAI)
Disputation
(Engelska)
Tillgänglig från: 2008-09-30 Skapad: 2009-05-06 Senast uppdaterad: 2009-07-13Bibliografiskt granskad

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Edström, Per

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