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[{"key": "dc.contributor.author", "value": "Voutilainen, Mikko", "language": null, "element": "contributor", "qualifier": "author", "schema": "dc"}, {"key": "dc.date.accessioned", "value": "2022-07-21T09:30:03Z", "language": null, "element": "date", "qualifier": "accessioned", "schema": "dc"}, {"key": "dc.date.available", "value": "2022-07-21T09:30:03Z", "language": null, "element": "date", "qualifier": "available", "schema": "dc"}, {"key": "dc.date.issued", "value": "2012", "language": null, "element": "date", "qualifier": "issued", "schema": "dc"}, {"key": "dc.identifier.isbn", "value": "978-951-39-9359-7", "language": null, "element": "identifier", "qualifier": "isbn", "schema": "dc"}, {"key": "dc.identifier.uri", "value": "https://jyx.jyu.fi/handle/123456789/82395", "language": null, "element": "identifier", "qualifier": "uri", "schema": "dc"}, {"key": "dc.description.abstract", "value": "This work deals with two important factors of the element transport in geological\r\nmaterials. Firstly, element diffusion is an important migration process in geological\r\nmaterials, especially when considering transport next to water conducting fractures\r\nand shear zones. Secondly, the structure of the pore network forms an environment\r\nfor migration of elements to take place. These two factors are important when considering\r\nradionuclide transport in geological materials in which all affecting processes are\r\nnot fully understood yet. Therefore further information and development of analysis\r\nmethods are needed.\r\nFirst of all, a semi-analytical solution for advection-matrix diffusion equations in the\r\ncase of a well-mixed flow past a porous matrix was developed. Solution is based on a\r\nLaplace transform of the equation and on using appropriate dimensionless variables.\r\nThe matrix-diffusion models considered here include the effects of a finite depth of\r\nthe matrix, varying aperture of the flow channel, the shape of the input pulse, and\r\nlongitudinal diffusion and Taylor dispersion of the element in the flow channel as well\r\nas a non-zero initial element concentration in the matrix.\r\nIn order to validate the developed solutions, a measuring system was constructed.\r\nMatrix diffusion was illustrated by observing the migration of KCl-tracer in the water\r\nflowing through a channel facing a porous matrix. Migration of K+ and Cl\u2212 ions was\r\nmonitored by measuring the electrical conductivity of the solution. The experimental\r\nsystem allowed also measurement of the concentration profile inside the porous matrix,\r\nbut the focus was here on the input and output (breakthrough) curves. The effects\r\nof a finite depth of the matrix and non-zero initial concentration of tracer, predicted\r\nby semi-analytical solutions, were successfully validated by the experiments.\r\nSecondly, a method to characterize pore network and mineral distribution of geological\r\nmaterials was developed using X-ray micro computed tomography (X-\u03bcCT),\r\n14C-labeled-polymethylmethacrylate (14C-PMMA) method, and scanning electron microscopy\r\n(SEM). As an example a sample of altered Sievi tonalite was used. X-\u03bcCT\r\nwas used to create 3D density maps of the samples from which different minerals and\r\npores were segmented. From these density maps mineral abundances, porosity, connectivity,\r\nporosity distribution and pore size distribution were determined, together\r\nwith qualitative information about the structure of minerals and pores.\r\nX-\u03bcCT offers information only of structures whose size is above the detection limit.\r\nIn order to get information below this limit, the 14C-PMMA method and SEM were\r\napplied. Different minerals in the sample were identified by SEM, after which these\r\nminerals were linked to different components observed in the X-\u03bcCT images. The 14C-PMMA method gives a 2D porosity map of imaged rock surface in which porosity\r\nof each pixel represents the averaged porosity over its area, and thus it offers information\r\neven from nanometer scale. Further, this information was used to determine the\r\nintragranular porosities by superimposing the 2D porosity map with stained and segmented\r\nimage of the corresponding rock surface and then averaging the pixel porosities\r\nover each mineral. Finally, 3D porosity maps of the samples were constructed by\r\ncombining intragranular porosities and segmented tomographic images.\r\nThirdly, these research issues above were combined by modeling diffusion in tomographic\r\nimages using time domain diffusion (TDD) simulations. The TDD method is\r\na fast particle tracking method which allows to model diffusion in 3D heterogeneous\r\nmedia when local porosities and diffusion coefficients are known. The method was\r\nfirst validated in various cases including comparison to analytical and numerical solution\r\nof the diffusion equation. In addition, the results produced by the method were\r\ncompared to ones by discrete-time random-walk simulations.\r\nTDD simulations were first applied to analyzing a diffusion experiment of tritiated\r\nwater (HTO) in altered Sievi tonalite and to determine the apparent diffusion coefficient.\r\nThen the TDD method was applied to study the effect of material heterogeneity\r\non diffusion processes using a sample of altered Sievi tonalite. This study was done by\r\ncomparing simulated in-diffusion profiles in samples with heterogeneous and homogeneous\r\ndistribution of porosity and known diffusion coefficients. In the case of altered\r\nSievi tonalite, inclusion of heterogeneity in the porosity increased the apparent diffusion\r\ncoefficient by 16%. The method was also found to be suitable when considering\r\nthe effects of different mineral components and diffusion direction.", "language": "en", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Submitted by Paivi Vuorio (paelvuor@jyu.fi) on 2022-07-21T09:30:03Z\r\nNo. of bitstreams: 0", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.description.provenance", "value": "Made available in DSpace on 2022-07-21T09:30:03Z (GMT). No. of bitstreams: 0\r\n Previous issue date: 2012", "language": "en", "element": "description", "qualifier": "provenance", "schema": "dc"}, {"key": "dc.language.iso", "value": "eng", "language": null, "element": "language", "qualifier": "iso", "schema": "dc"}, {"key": "dc.relation.ispartofseries", "value": "Jyv\u00e4skyl\u00e4n yliopisto. Fysiikan laitos. Research report", "language": null, "element": "relation", "qualifier": "ispartofseries", "schema": "dc"}, {"key": "dc.relation.haspart", "value": "<b>Artikkeli I:</b> Voutilainen, M., Lamminm\u00e4ki, S., Timonen, J., Siitari-Kauppi, M., & Breitner, D. (2009). Physical Rock Matrix Characterization: Structural and Mineralogical Heterogeneities in Granite. <i>MRS Online Proceedings Library, 1124, 703.</i> DOI: <a href=\"https://doi.org/10.1557/proc-1124-q07-03\"target=\"_blank\"> 10.1557/proc-1124-q07-03</a>", "language": null, "element": "relation", "qualifier": "haspart", "schema": "dc"}, {"key": "dc.relation.haspart", "value": "<b>Artikkeli II:</b> Voutilainen, M., Kek\u00e4l\u00e4inen, P., Hautoj\u00e4rvi, A., & Timonen, J. (2010). Validation of matrix diffusion modeling. <i>Physics and Chemistry of the Earth, Parts A/B/C, 35(6\u20138), 259-264.</i> DOI: <a href=\"https://doi.org/10.1016/j.pce.2010.04.005\"target=\"_blank\"> 10.1016/j.pce.2010.04.005</a>", "language": null, "element": "relation", "qualifier": "haspart", "schema": "dc"}, {"key": "dc.relation.haspart", "value": "<b>Artikkeli III:</b> Kek\u00e4l\u00e4inen, P., Voutilainen, M., Poteri, A., H\u00f6ltt\u00e4, P., Hautoj\u00e4rvi, A., & Timonen, J. (2011). Solutions to and validation of matrix-diffusion models. <i>Transport in Porous Media, 87(1), 125-149.</i> DOI: <a href=\"https://doi.org/10.1007/s11242-010-9672-y\"target=\"_blank\"> 10.1007/s11242-010-9672-y </a>", "language": null, "element": "relation", "qualifier": "haspart", "schema": "dc"}, {"key": "dc.relation.haspart", "value": "<b>Artikkeli IV:</b> Voutilainen, M., Siitari-Kauppi, M., Sardini, P., Lindberg, A., & Timonen, J. (2012). Pore-space characterization of an altered tonalite by X-ray computed microtomography and the ^{14}C-labeled-polymethylmethacrylate method. <i>Journal of Geophysical Research, 117(B1), 14.</i> DOI: <a href=\"https://doi.org/10.1029/2011JB008622\"target=\"_blank\"> 10.1029/2011JB008622</a>", "language": null, "element": "relation", "qualifier": "haspart", "schema": "dc"}, {"key": "dc.relation.haspart", "value": "<b>Artikkeli V:</b> Voutilainen, M., Sardini, P., Siitari-Kauppi, M., Kek\u00e4l\u00e4inen, P., Aho, V., Myllys, M., & Timonen, J. (2013). Diffusion of tracer in altered tonalite: Experiments and simulations with heterogeneous distribution of porosity. <i>Transport in Porous Media, 96(2), 319-336.</i> DOI: <a href=\"https://doi.org/10.1007/s11242-012-0090-1\"target=\"_blank\"> 10.1007/s11242-012-0090-1</a>", "language": null, "element": "relation", "qualifier": "haspart", "schema": "dc"}, {"key": "dc.rights", "value": "In Copyright", "language": null, "element": "rights", "qualifier": null, "schema": "dc"}, {"key": "dc.title", "value": "Characterization of structure and diffusion in geological materials", "language": null, "element": "title", "qualifier": null, "schema": "dc"}, {"key": "dc.type", "value": "doctoral thesis", "language": null, "element": "type", "qualifier": null, "schema": "dc"}, {"key": "dc.identifier.urn", "value": "URN:ISBN:978-951-39-9359-7", "language": null, "element": "identifier", "qualifier": "urn", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Faculty of Mathematics and Science", "language": "en", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.faculty", "value": "Matemaattis-luonnontieteellinen tiedekunta", "language": "fi", "element": "contributor", "qualifier": "faculty", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "University of Jyv\u00e4skyl\u00e4", "language": "en", "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.contributor.organization", "value": "Jyv\u00e4skyl\u00e4n yliopisto", "language": "fi", "element": "contributor", "qualifier": "organization", "schema": "dc"}, {"key": "dc.type.coar", "value": "http://purl.org/coar/resource_type/c_db06", "language": null, "element": "type", "qualifier": "coar", "schema": "dc"}, {"key": "dc.relation.issn", "value": "0075-465X", "language": null, "element": "relation", "qualifier": "issn", "schema": "dc"}, {"key": "dc.rights.accesslevel", "value": "openAccess", "language": null, "element": "rights", "qualifier": "accesslevel", "schema": "dc"}, {"key": "dc.type.publication", "value": "doctoralThesis", "language": null, "element": "type", "qualifier": "publication", "schema": "dc"}, {"key": "dc.rights.url", "value": "https://rightsstatements.org/page/InC/1.0/", "language": null, "element": "rights", "qualifier": "url", "schema": "dc"}]
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