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Stjernberg, Jesper
Publications (10 of 16) Show all publications
Stjernberg, J., Nordin, L.-O. & Ion, J. (2015). Evaluation of refractory castables and coatings used in the pre-heat zone of a grate-kiln for iron ore pellet production (ed.). Paper presented at . Ironmaking & steelmaking, 42(4), 274-281
Open this publication in new window or tab >>Evaluation of refractory castables and coatings used in the pre-heat zone of a grate-kiln for iron ore pellet production
2015 (English)In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 42, no 4, p. 274-281Article in journal (Refereed) Published
Abstract [en]

Iron ore pellets are a prepared burden material for ironmaking that are commonly sintered in a grate kiln furnace system. Deposited material can adhere in chunks to localised regions of the lining of such furnaces, causing lining depletion. Such deposits consist mainly of iron oxides, but alkali, alkaline earth and other oxides formed from disintegrated pellets and fly ash may also be present. In order to investigate methods of preventing such formations, tests have been performed using several different castables and coatings. Samples of liner castables with and without coatings, installed in an industrial furnace, were collected after 6 and 24 months in production use, and characterised using scanning electron microscopy to identify the materials, characterise morphological changes at the deposit-coating-lining interface, and to determine the active chemical reactions. An Al2O3 based coating applied to one of the fields was found to be in good condition after 6 months in use, but no traces of the coating were observed after 24 months in use. A carbon phosphate based coating was not intact after 6 months in use; it was probably burned-up as a result of the oxidising atmosphere. Hematite grains from the deposit material remained at the original deposit-lining interface, while calcium migrated further into the lining.

National Category
Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-11336 (URN)10.1179/1743281214Y.0000000226 (DOI)000353708600006 ()2-s2.0-84980377988 (Scopus ID)a47953f7-b558-47d2-a001-52bf9b8739e3 (Local ID)a47953f7-b558-47d2-a001-52bf9b8739e3 (Archive number)a47953f7-b558-47d2-a001-52bf9b8739e3 (OAI)
Note
Validerad; 2015; Nivå 2; 20140908 (jessje)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Stjernberg, J., Isaksson, O. & Ion, J. (2015). The grate-kiln induration machine: history, advantages, and drawbacks, and outline for the future (ed.). The Journal of The Southern African Institute of Mining and Metallurgy, 115(2), 137-144
Open this publication in new window or tab >>The grate-kiln induration machine: history, advantages, and drawbacks, and outline for the future
2015 (English)In: The Journal of The Southern African Institute of Mining and Metallurgy, ISSN 2411-9717, Vol. 115, no 2, p. 137-144Article in journal (Refereed) Published
Abstract [en]

Iron ore pellets are a preferred feedstock for ironmaking. One method used for pelletizing is the grate-kiln process, first established in 1960. During the past decade, the establishment of new grate-kiln plants has increased rapidly, especially in China, and new constructors of pellet plants have started to operate in the market. It is well known that the grate-kiln method yields a superior and more consistent pellet quality compared with the straight-grate process. However, certain issues exist with the grate-kiln plant, which are discussed here, together with proposed practical solutions.

National Category
Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-4040 (URN)1e5ae2e2-274d-4367-8943-d49c4762db5f (Local ID)1e5ae2e2-274d-4367-8943-d49c4762db5f (Archive number)1e5ae2e2-274d-4367-8943-d49c4762db5f (OAI)
Note

Validerad; 2015; Nivå 2; 20150219 (jessje)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-02-15Bibliographically approved
Wiinikka, H., Weiland, F., Pettersson, E., Öhrman, O., Carlsson, P. & Stjernberg, J. (2014). Characterisation of submicron particles produced during oxygen blown entrained flow gasification of biomass (ed.). Paper presented at . Combustion and Flame, 161(7), 1923-1934
Open this publication in new window or tab >>Characterisation of submicron particles produced during oxygen blown entrained flow gasification of biomass
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2014 (English)In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 161, no 7, p. 1923-1934Article in journal (Refereed) Published
Abstract [en]

In this paper submicron particles sampled after the quench during 200 kW, 2 bar(a) pressurised, oxygen blown gasification of three biomass fuels, pure stem wood of pine and spruce, bark from spruce and a bark mixture, have been characterised with respect to particle size distribution with a low pressure cascade impactor. The particles were also characterised for morphology and elemental composition by a combination of scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and high resolution transmission electron microscopy/energy dispersive spectroscopy/selected area electron diffraction pattern (HRTEM/EDS/SAED) techniques. The resulting particle concentration in the syngas after the quench varied between 46 and 289 mg/Nm3 consisting of both carbon and easily volatile ash forming element significantly depending on the fuel ash content. Several different types of particles could be identified from classic soot particles to pure metallic zinc particles depending on the individual particle relation of carbon and ash forming elements. The results also indicate that ash forming elements and especially zinc interacts in the soot formation process creating a particle with shape and microstructure significantly different from a classical soot particle.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-3447 (URN)10.1016/j.combustflame.2014.01.004 (DOI)000337200700020 ()2-s2.0-84901625416 (Scopus ID)1451860f-0982-463f-b03f-8e4cfea8dd3b (Local ID)1451860f-0982-463f-b03f-8e4cfea8dd3b (Archive number)1451860f-0982-463f-b03f-8e4cfea8dd3b (OAI)
Note
Validerad; 2014; 20140128 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ramanenka, D., Stjernberg, J., Eriksson, K. & Jonsén, P. (2014). Modelling of refractory brick furniture in rotary-kiln using finite element approach (ed.). In: (Ed.), Eugenio Oñate; Xavier Oliver; Antonio Huerta (Ed.), 11th World Congress on Computational Mechanics (WCCM XI) 5th European Conference on Computational Mechanics (ECCM V) 6th European Conference on Computational Fluid Dynamics (ECFD VI): . Paper presented at World Congress on Computational Mechanics (WCCM XI) : 5th European Conference on Computational Mechanics (ECCM V) 6th European Conference on Computational Fluid Dynamics (ECFD VI) 20/07/2014 - 25/07/2014 (pp. 1199-1210). Barcelona: International Center for Numerical Methods in Engineering (CIMNE), 2
Open this publication in new window or tab >>Modelling of refractory brick furniture in rotary-kiln using finite element approach
2014 (English)In: 11th World Congress on Computational Mechanics (WCCM XI) 5th European Conference on Computational Mechanics (ECCM V) 6th European Conference on Computational Fluid Dynamics (ECFD VI) / [ed] Eugenio Oñate; Xavier Oliver; Antonio Huerta, Barcelona: International Center for Numerical Methods in Engineering (CIMNE), 2014, Vol. 2, p. 1199-1210Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Barcelona: International Center for Numerical Methods in Engineering (CIMNE), 2014
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-40226 (URN)f4533996-c19a-4e1f-a146-3e864c2f152b (Local ID)978-84-942844-7-2 (ISBN)f4533996-c19a-4e1f-a146-3e864c2f152b (Archive number)f4533996-c19a-4e1f-a146-3e864c2f152b (OAI)
Conference
World Congress on Computational Mechanics (WCCM XI) : 5th European Conference on Computational Mechanics (ECCM V) 6th European Conference on Computational Fluid Dynamics (ECFD VI) 20/07/2014 - 25/07/2014
Note
Godkänd; 2014; 20140813 (parj)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Jonsson, C., Wiinikka, H., Lindblom, B., Stjernberg, J. & Öhman, M. (2013). Comparison of particle and deposit formation between a full-scale grate-kiln plant (40 MW) and a pilot-scale pulverised coal-fired furnace (400 kW) (ed.). Paper presented at International Conference on Applied Energy : Energy Solution for a Sustainable World 01/07/2013 - 05/07/2013. Paper presented at International Conference on Applied Energy : Energy Solution for a Sustainable World 01/07/2013 - 05/07/2013.
Open this publication in new window or tab >>Comparison of particle and deposit formation between a full-scale grate-kiln plant (40 MW) and a pilot-scale pulverised coal-fired furnace (400 kW)
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2013 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

The iron ore pelletizing industry utilizes the grate-kilnprocess to dry and sinter the pellets into finished product.The grate-kiln process has a known deposit formation issuethat needs to be further understood. Combustion ofpulverised coal in the rotary kiln generates fly ash particles;in addition to that, particles generated from disintegratediron ore pellets are also entrained in the process gas stream.The combined effect of both sources of particles cantherefore contribute to the deposit formation in the process.In this work, particle- and deposit formation were studiedboth from a full-scale grate-kiln plant (40 MW) and from apilot-scale pulverised coal fired furnace (400 kW). Particleswere collected with a water-cooled probe with nitrogen gasas dilution medium at the tip of the probe. The particleswere separated simultaneously with a pre-cyclone and a 13stages low-pressure impactor during samplings. Depositswere collected with a refractory plate which was attachedat the tip of a water-cooled probe, exposed to the hightemperature (>1100 °C) process gas stream. Particles anddeposits were characterized with an environmentalscanning electron microscope and a scanning electronmicroscope that equipped with energy dispersivespectroscopy detector. A comparison of particle and depositcharacteristics between the grate-kiln plant and the pilotscale pulverised coal fired furnace is presented in this paper,with focus on the potential influence of disintegrated ironore pellets on the particle- and deposit formation process.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-32053 (URN)669ad7a9-7884-456b-9019-d3048b1d2d04 (Local ID)669ad7a9-7884-456b-9019-d3048b1d2d04 (Archive number)669ad7a9-7884-456b-9019-d3048b1d2d04 (OAI)
Conference
International Conference on Applied Energy : Energy Solution for a Sustainable World 01/07/2013 - 05/07/2013
Note
Godkänd; 2013; 20130819 (carjon)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-05-02Bibliographically approved
Jonsson, C., Stjernberg, J., Wiinikka, H., Lindblom, B., Boström, D. & Öhman, M. (2013). Deposit formation in a grate-kiln plant for iron-ore pellet production: Part 1: Characterization of process gas particles (ed.). Paper presented at . Energy & Fuels, 27(10), 6159-6170
Open this publication in new window or tab >>Deposit formation in a grate-kiln plant for iron-ore pellet production: Part 1: Characterization of process gas particles
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2013 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 10, p. 6159-6170Article in journal (Refereed) Published
Abstract [en]

Slag formation in the grate-kiln process is a major problem for iron-ore pellet producers. It is therefore important to understand the slag formation mechanism in the grate-kiln production plant. This study initiated the investigation by in situ sampling and identifying particles in the flue gas from a full-scale 40 MW grate-kiln production plant for iron-ore pelletizing. Particles were sampled from two cases of combustion with pulverized coal and heavy fuel oil. The sampling location was at the transfer chute that was situated between the traveling grate and the rotary kiln. The particle-sampling system was set up with a water-cooled particle probe equipped with nitrogen gas dilution, cyclone, and low-pressure impactor. Sub-micrometer and fine particles were size-segregated in the impactor, while coarse particles (>6 μm) were separated with a cyclone before the impactor. Characterization of these particles was carried out with environmental scanning electron microscopy (ESEM), and the morphology of sub-micrometer particles was studied with transmission electron microscopy (TEM). The results showed that particles in the flue gas consisted principally of fragments from iron-ore pellets and secondarily of ashes from pulverized coal and heavy fuel oil combustions. Three categories of particle modes were identified: (1) sub-micrometer mode, (2) first fragmentation mode, and (3) second fragmentation mode. The sub-micrometer mode consisted of vaporized and condensed species; relatively high concentrations of Na and K were observed for both combustion cases, with higher concentrations of Cl and S from heavy fuel oil combustion but higher concentrations of Si and Fe and minor P, Ca, and Al from coal combustion. The first fragmentation mode consisted of both iron-ore pellet fines and fly ash particles; a significant increment of Fe (>65 wt %) was observed, with higher concentrations of Ca and Si during heavy fuel oil combustion but higher concentrations of Si and Al during coal combustion. The second fragmentation mode consisted almost entirely of coarse iron-ore pellet fines, predominantly of Fe (90 wt %). The particles in the flue gas were dominantly iron-ore fines because the second fragmentation mode contributed >96 wt % of the total mass of collected particles.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-4917 (URN)10.1021/ef400973w (DOI)000326126700065 ()2-s2.0-84886001749 (Scopus ID)2eb9fd70-d7a1-45a3-bf9b-495114fa4183 (Local ID)2eb9fd70-d7a1-45a3-bf9b-495114fa4183 (Archive number)2eb9fd70-d7a1-45a3-bf9b-495114fa4183 (OAI)
Note
Validerad; 2013; 20130826 (ohmmar)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Stjernberg, J., Jonsson, C., Wiinikka, H., Lindblom, B., Boström, D. & Öhman, M. (2013). Deposit formation in a grate-kiln plant for iron-ore pellet production: Part 2: Characterization of deposits (ed.). Paper presented at . Energy & Fuels, 27(10), 6171-6184
Open this publication in new window or tab >>Deposit formation in a grate-kiln plant for iron-ore pellet production: Part 2: Characterization of deposits
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2013 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 10, p. 6171-6184Article in journal (Refereed) Published
Abstract [en]

Buildup of deposit material in chunks on refractory linings caused by combustion of various fuels is a well-known problem. This study characterizes the short-term deposits on refractory material in a grate–kiln process, carried out through in situ measurements using a water-cooled probe with a part of a refractory brick mounted in its end. Sampling was carried out during combustion of both oil and coal. A significant difference in deposition rates was observed; deposition during oil firing was negligible compared to coal firing. The deposits are mainly hematite particles embedded in bonding phase, mainly comprising Si, Al, Fe, Ca, and O. Moreover, it was found that the prevailing flue-gas direction determines the formation of the deposits on the probe and that inertial impaction controls the deposition rate. However, this rate can also be affected by the amount of air-borne particles present in the kiln.

National Category
Other Materials Engineering Energy Engineering
Research subject
Engineering Materials; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-6117 (URN)10.1021/ef4009746 (DOI)000326126700066 ()2-s2.0-84886024325 (Scopus ID)45127016-13d8-41a3-9d0a-8488f256c597 (Local ID)45127016-13d8-41a3-9d0a-8488f256c597 (Archive number)45127016-13d8-41a3-9d0a-8488f256c597 (OAI)
Note
Validerad; 2013; 20130722 (ohmmar)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Stjernberg, J., Olivas-Ogaz, M., Antti, M.-L., Ion, J. & Lindblom, B. (2013). Laboratory scale study of the degradation of mullite/corundum refractories by reaction with alkali-doped deposit materials (ed.). Ceramics International, 39(1), 791-800
Open this publication in new window or tab >>Laboratory scale study of the degradation of mullite/corundum refractories by reaction with alkali-doped deposit materials
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2013 (English)In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 39, no 1, p. 791-800Article in journal (Refereed) Published
Abstract [en]

Refractory bricks based on mullite and corundum, commonly used in rotary kilns for iron ore pellet production, and depositmaterial from an iron ore pellet production kiln, were used in laboratoryscale tests to investigate refractory/depositreactions and the infiltration of deposit components into the refractory bricks. The materials tested were in both monolithic form and in the form of powder. Alkali metal carbonates (containing sodium and potassium) were used as corrosive agents, to increase reaction kinetics. The morphological changes and active chemical reactions at the refractory/deposit interface in the samples were characterized by scanning electron microscopy. X-ray diffraction showed that alkali metals react with the mullite in the bricks, this being more pronounced in the case of sodium than potassium. Phases such as nepheline (Na2O·Al2O3·2SiO2), kalsilite and kaliophilite (both K2O·Al2O3·2SiO2), and leucite (K2O·Al2O3·4SiO2) were formed as a consequence of reactions between alkali metals and the refractory bricks. The formation of these phases causes volume expansions of between 20% and 25% in the brick materials, which accelerate degradation.

National Category
Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-4093 (URN)10.1016/j.ceramint.2012.06.094 (DOI)000315246300101 ()2-s2.0-84869090211 (Scopus ID)1f657a6a-588a-4cca-8db6-2c180356ceae (Local ID)1f657a6a-588a-4cca-8db6-2c180356ceae (Archive number)1f657a6a-588a-4cca-8db6-2c180356ceae (OAI)
Note

Validerad; 2013; 20120731 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-08-23Bibliographically approved
Stjernberg, J. (2012). Degradation mechanisms in refractory lining materials of rotary kilns for iron ore pellet production (ed.). (Doctoral dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Degradation mechanisms in refractory lining materials of rotary kilns for iron ore pellet production
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Iron is one of the most important resources in the lithosphere; 90% of all metal ores extracted are based on iron. Many steps are included in the extraction of iron from ore, with extraction processes varying among different producers. Iron ore pellets are a prepared burden material for ironmaking in the blast furnace or by direct reduction. Such pellets can be sintered in a grate-kiln furnace system, in which the kiln is usually lined with mullite-containing bricks. These bricks degrade by various mechanisms, and need to be replaced regularly, which causes expensive production stops. Materials deposit in chunks on the lining in the kiln. These deposits comprise ~95% hematite with oxides of alkali metals, alkaline earth metals and others, which originate mainly from pellets that have disintegrated, but also from fly-ash from the burner fuel used to heat the kiln.This study investigated the interaction of deposit materials with refractory lining bricks in kilns during the sintering process in iron ore pellet production. Results are obtained from laboratory scale experiments, and from samples collected from industrial kilns, both in-situ and during production stops. Refractory/deposit compatibility tests were performed in a laboratory furnace at various temperatures, for different holding times, and in a number of atmospheres. Deposit materials collected from three commercial lining bricks in production kilns were analysed in both powder and solid forms. Deliberate additions of alkali species (carbonates of potassium and sodium) were made in order to evaluate their influence on degradation mechanisms.Analysis using scanning electron microscopy, QEMSCAN (quantitative evaluation of minerals by scanning electron microscopy), x-ray diffraction, differential scanning calorimetry, thermogravimetry and in-situ mass spectrometry confirmed that alkali additions in the deposit materials dissolve mullite in the liner bricks, which accelerates degradation. Phases such as nepheline (Na2O·Al2O3·2SiO2), kalsilite (K2O·Al2O3·2SiO2), leucite (K2O·Al2O3·4SiO2) and potassium β-alumina (K2O·11Al2O3) were formed. Moreover, it was observed that potassium penetrates deeper into the lining material, and in larger amounts, than sodium, both on the laboratory scale and in industrial furnaces. Formations of alkalicontaining phases such as the feldspathoid minerals kalsilite and nepheline are coupled with an expansion in the lining material, observed by dilatometry, which causes structural spalling that appears as cracks in some of the refractory/deposit compatibility tests. Grains of hematite with sizes between 50-100 μm remain on the original surface of the brick, whereas micrometer-scale hematite migrates through capillary infiltration (in pores, brick joints and cracks) and diffusion, and appears in finer grains deeper in the lining material. The degradation mechanisms of the bricks in an iron ore pellet producing kiln are shown to involve these chemical reactions in combination with thermomechanical stresses. Recommendations are given regarding the choice of materials, the design of refractory liners in the kilns to extend the time between production stops necessary for repair.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2012
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-17423 (URN)35a32fdd-ec04-4942-93ba-84a2d7d83508 (Local ID)978-91-7439-402-3 (ISBN)35a32fdd-ec04-4942-93ba-84a2d7d83508 (Archive number)35a32fdd-ec04-4942-93ba-84a2d7d83508 (OAI)
Note
Godkänd; 2012; 20120114 (jessje); DISPUTATION Ämnesområde: Konstruktionsmaterial/Engineering Materials Opponent: Professor Marc Huger, Groupe d’Etude des Matériaux Hétérogènes, Centre Européen de la Ceramique (CEC), Limoges/Ecole Nationale Superiéure de Céramique Industriell (ENSCI) de Limoges, France Ordförande: Docent John Ion, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Tisdag den 13 mars 2012, kl 10.00 Plats: E231, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Stjernberg, J., Ion, J., Antti, M.-L., Nordin, L.-O., Lindblom, B. & Odén, M. (2012). Extended studies of degradation mechanisms in the refractory lining of a rotary kiln for iron ore pellet production (ed.). Paper presented at . Journal of the European Ceramic Society, 32(8), 1519-1528
Open this publication in new window or tab >>Extended studies of degradation mechanisms in the refractory lining of a rotary kiln for iron ore pellet production
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2012 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 32, no 8, p. 1519-1528Article in journal (Refereed) Published
Abstract [en]

Changes, over a period of 8 years, in the chemical composition and morphology of deposit and lining materials in a production rotary kiln for iron ore pellet manufacture are described. The following have been studied: two types of refractory brick used as lining material; deposited chunk materials from the lining; the interaction zones between deposits and linings. Morphological changes at the deposit/lining interface, and the active chemical reactions, are established. Larger hematite grains in the deposit material (5–50 μm) primarily remain at the original deposit/lining interface. The remainder penetrates fissures, voids and brick joints, forms a laminar structure with corundum from the bricks, and migrates in grains in the lining material. Potassium penetrates more deeply into the bricks than hematite, resulting in the formation of kalsilite, leucite and potassium β-alumina, which contribute to degradation of the lining.

National Category
Other Materials Engineering
Research subject
Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-9458 (URN)10.1016/j.jeurceramsoc.2012.01.012 (DOI)000303279600007 ()2-s2.0-84858701944 (Scopus ID)818e7c3a-6f72-4ca0-b9f5-ae7c6874d543 (Local ID)818e7c3a-6f72-4ca0-b9f5-ae7c6874d543 (Archive number)818e7c3a-6f72-4ca0-b9f5-ae7c6874d543 (OAI)
Note
Validerad; 2012; 20120208 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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