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  • 1451.
    Samuel, Baiye Tanyi
    Örebro University, School of Science and Technology.
    Analysis of Mutations and Polymorphisms in PIk3CA, EGFR and MDM2 rs22797442012Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 1452.
    Sand Ekmark, Fredrik
    Örebro University, School of Science and Technology.
    Screening for Cryptosporidium and Coliforms from Waters around Östersund and Åre2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 1453.
    Sandin, Patrik
    et al.
    Örebro University, School of Science and Technology.
    Ögren, Magnus
    Örebro University, School of Science and Technology.
    Gulliksson, Mårten
    Örebro University, School of Science and Technology. Univ Orebro, Sch Sci & Technol, S-70182 Orebro, Sweden..
    Numerical solution of the stationary multicomponent nonlinear Schrodinger equation with a constraint on the angular momentum2016In: Physical Review E, ISSN 2470-0045, Vol. 93, no 3, 033301Article in journal (Refereed)
    Abstract [en]

    We formulate a damped oscillating particle method to solve the stationary nonlinear Schrodinger equation (NLSE). The ground-state solutions are found by a converging damped oscillating evolution equation that can be discretized with symplectic numerical techniques. The method is demonstrated for three different cases: for the single-component NLSE with an attractive self-interaction, for the single-component NLSE with a repulsive self-interaction and a constraint on the angular momentum, and for the two-component NLSE with a constraint on the total angular momentum. We reproduce the so-called yrast curve for the single-component case, described in [A. D. Jackson et al., Europhys. Lett. 95, 30002 (2011)], and produce for the first time an analogous curve for the two-component NLSE. The numerical results are compared with analytic solutions and competing numerical methods. Our method is well suited to handle a large class of equations and can easily be adapted to further constraints and components.

  • 1454.
    Sandin, Patrik
    et al.
    Örebro University, School of Science and Technology.
    Ögren, Magnus
    Örebro University, School of Science and Technology.
    Gulliksson, Mårten
    Örebro University, School of Science and Technology.
    Smyrnakis, J.
    Technological Education Institute of Crete, Heraklion, Greece.
    Magiropoulos, M.
    Technological Education Institute of Crete, Heraklion, Greece.
    Kavoulakis, G. M.
    Technological Education Institute of Crete, Heraklion, Greece.
    Dimensional reduction in Bose-Einstein condensed clouds of atoms confined in tight potentials of any geometry and any interaction strength2017In: Physical Review E, ISSN 2470-0045, Vol. 95, no 1, 012142Article in journal (Refereed)
    Abstract [en]

    Motivated by numerous experiments on Bose-Einstein condensed atoms which have been performed in tight trapping potentials of various geometries (elongated and/or toroidal/annular), we develop a general method which allows us to reduce the corresponding three-dimensional Gross-Pitaevskii equation for the order parameter into an effectively one-dimensional equation, taking into account the interactions (i.e., treating the width of the transverse profile variationally) and the curvature of the trapping potential. As an application of our model we consider atoms which rotate in a toroidal trapping potential. We evaluate the state of lowest energy for a fixed value of the angular momentum within various approximations of the effectively one-dimensional model and compare our results with the full solution of the three-dimensional problem, thus getting evidence for the accuracy of our model.

  • 1455. Sanfeliu, Alberto
    et al.
    Hagita, Norihiro
    Saffiotti, Alessandro
    Örebro University, School of Science and Technology.
    Special issue: Network robot systems2008In: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 56, no 10, 791-791 p.Article in journal (Refereed)
  • 1456.
    Saqib, Naeem
    Örebro University, School of Science and Technology.
    Distribution and chemical association of trace elements in incinerator residues and mining waste from a leaching perspective2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Incineration is a mainstream strategy for solid waste management in Sweden and all over the world. Improved knowledge and understanding about the distribution of trace elements (in ashes) during incineration, and how trace element partitioning respond to the changes in waste composition, are important in terms of combustion process optimization and plant efficiency. Moreover, determination of chemical association of trace elements in ashes are vital for avoiding environmental concerns and to promote possible reuse. In this study, partitioning of trace elements in ashes during incineration as function of input waste fuel and incineration technology was investigated. Further, chemical association of trace elements in resulting ashes was studied. An evaluation was also performed about feasibility of metal extraction from sulfidic mining waste and flotation tailings. Moreover, green liquor dreg (GLD) was tested with respect to stabilization of metals within the sulfidic mining waste.

    Findings showed that the total input of trace elements and chlorine affects the partitioning and increasing chlorine in the input waste caused increase in transfer of trace elements to fly ash especially for lead and zinc. Vaporization, condensation on fly ash particles and adsorption mechanisms play an important role for metal distribution. Firing mixed waste, especially biofuel mix, in grate or fluidized (CFB) boilers caused increased transfer into fly ash for almost all trace elements particularly lead and zinc. Possible reasons might be either an increased input concentration of respective element in the waste fuel, or a change in volatilization behavior due to the addition of certain waste fractions. Chemical association study for fly ashes indicated that overall, Cd, Pb, Zn, Cu and Sb are presenting major risk in most of the fly ashes, while in bottom ashes, most of elements are associated with stable fraction. Further, fuel type affects the association of elements in ashes. Chemical leaching of mining waste materials showed that sulfuric acid (under different conditions) is the best reagent to recover zinc and copper from sulfidic mining waste and also copper from flotation tailings. GLD indicates potential for metal stabilization in mining waste by reducing the metal mobility. Extraction methods could be applied to treat mining waste in order to meet the regulatory level at a specific mining site.Similarly stabilization/solidification  methods might be applied after leaching for recovery of metals.

    List of papers
    1. Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature
    Open this publication in new window or tab >>Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature
    2014 (English)In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 34, no 12, 2505-2519 p.Article in journal (Refereed) Published
    Abstract [en]

    Trace element partitioning in solid waste (household waste, industrial waste, waste wood chips and waste mixtures) incineration residues was investigated. Samples of fly ash and bottom ash were collected from six incineration facilities across Sweden including two grate fired and four fluidized bed incinerators, to have a variation in the input fuel composition (from pure biofuel to mixture of waste) and different temperature boiler conditions. As trace element concentrations in the input waste at the same facilities have already been analyzed, the present study focuses on the concentration of trace elements in the waste fuel, their distribution in the incineration residues with respect to chlorine content of waste and combustion temperature. Results indicate that Zn, Cu and Pb are dominating trace elements in the waste fuel. Highly volatile elements mercury and cadmium are mainly found in fly ash in all cases; 2/3 of lead also end up in fly ash while Zn, As and Sb show a large variation in distribution with most of them residing in the fly ash. Lithophilic elements such as copper and chromium are mainly found in bottom ash from grate fired facilities while partition mostly into fly ash from fluidized bed incinerators, especially for plants fuelled by waste wood or ordinary wood chips. There is no specific correlation between input concentration of an element in the waste fuel and fraction partitioned to fly ash. Temperature and chlorine content have significant effects on partitioning characteristics by increasing the formation and vaporization of highly volatile metal chlorides. Zinc and cadmium concentrations in fly ash increase with the incineration temperature.

    Keyword
    Ash; Incineration residue; Solid waste management; Trace element partitioning
    National Category
    Chemical Sciences Environmental Sciences
    Research subject
    Chemistry; Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-41179 (URN)10.1016/j.wasman.2014.08.025 (DOI)000347019700009 ()25263218 (PubMedID)2-s2.0-84910639884 (Scopus ID)
    Available from: 2015-01-13 Created: 2015-01-13 Last updated: 2017-12-05Bibliographically approved
    2. Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies
    Open this publication in new window or tab >>Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies
    2015 (English)In: Journal of Environmental Sciences(China), ISSN 1001-0742, E-ISSN 1878-7320, Vol. 36, no 1 Oct., 9-21 p.Article in journal (Refereed) Published
    Abstract [en]

    Impact of waste fuels (virgin/waste wood, mixed biofuel (peat, bark, wood chips) industrial, household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr, As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature. Total concentration in ashes decreased in order of Zn > Cu > Pb > Cr > Sb > As > Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers (especially for biofuel incineration). It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions. Concentration levels in ash and ash matrix properties (association of elements on ash particles) are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in > 50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.

    Place, publisher, year, edition, pages
    Science Press, 2015
    Keyword
    Incineration residues; Leaching behavior; Biofuel incineration; Metal distribution; Waste incineration
    National Category
    Chemical Sciences
    Research subject
    Environmental Chemistry; Chemistry
    Identifiers
    urn:nbn:se:oru:diva-45103 (URN)10.1016/j.jes.2015.03.006 (DOI)000362983500002 ()26456601 (PubMedID)2-s2.0-84943225103 (Scopus ID)
    Note

    Funding Agency:

    Varmeforsk (Thermal Engineering Research Association) Q4-251

    Available from: 2015-07-04 Created: 2015-07-04 Last updated: 2017-12-04Bibliographically approved
    3. Chemical association and mobility of trace elements in 13 different fuel incineration fly ashes
    Open this publication in new window or tab >>Chemical association and mobility of trace elements in 13 different fuel incineration fly ashes
    2015 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 165, 193-204 p.Article in journal (Refereed) Published
    Abstract [en]

    The migration of trace elements from waste incineration fly ash is problematic during utilization/ landfilling. This study investigated the chemical association and potential mobility of trace elements in fly ashes originating from incineration of different fuels [virgin wood, recovered waste wood (RWW), mixed wooden fuel/waste, household, industrial, and mixed waste]. Fly ashes were characterized for total content of trace elements, chemical association by sequential extraction and leaching behaviour by standard leaching method (EN 12457-3). Results showed that average total content of trace elements in 13 fly ashes decreased in the order Zn > Cu > Pb > Sb > Cr > As > Cd. Sequential extraction results indicated that overall, Cd, Pb, Zn, Cu and Sb were the most mobile elements and excessive leaching was associated with high content of acid exchangeable fractions. Sequential extraction showed thatthe average percentage of trace elements in labile and stable fractions for all 13 fly ashes decreased in the order:Cd > Cu > Sb > Zn > As > Pb > Cr (ion-exchangeable), Pb > Zn > Sb > Cd > Cu > As > Cr(acid soluble),Cr > As > Pb > Sb > Cu > Zn > Cd (residual). The standard leaching procedure of ashes indicated that the leached amount of Pb in all samples, Zn in 7 while Cu in 6 (out of 13) samples, respectively, exceeded the regulatory level for disposal. Moreover, principal component analysis (PCA) showed that fuel type affects the chemical association of trace elements in fly ash. Further, risk assessment code (RAC) suggested that most of fly ashes presented very high risk due to high RAC values for Cd, Zn, Cu and Sb.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keyword
    Chemical speciation; Fly ash; Risk assessment; Trace elements mobility; MSWI
    National Category
    Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-46305 (URN)10.1016/j.fuel.2015.10.062 (DOI)000364655000023 ()2-s2.0-84946087137 (Scopus ID)
    Available from: 2015-10-23 Created: 2015-10-23 Last updated: 2017-12-01Bibliographically approved
    4. Chemical association and mobility of trace elements in 13 different fuel incineration bottom ashes
    Open this publication in new window or tab >>Chemical association and mobility of trace elements in 13 different fuel incineration bottom ashes
    2016 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 172, 105-117 p.Article in journal (Refereed) Published
    Abstract [en]

    The release of trace elements from waste incineration bottom ash is problematic during utilization/landfilling. Thirteen bottom ashes (from various waste fuels and wooden/mixed wooden fuel) were investigated with respect to the total content, leaching behaviour by standard leaching procedure (EN 12457-3), and chemical association of trace elements by sequential extraction. Results showed that the content of trace elements in household/or industrial waste bottom ashes were of high level in comparison to in wooden/mixed wooden fuel/mixed wooden waste ashes. Type of fuel being treated greatly impacts the total inventory of trace elements. On average, trace element content in 13 ashes followed the decreasing order; Cu > Zn > Pb > Cr > Ni > Sb > As. In this study the average total content of Zn, Pb, Cu and Cr was higher in grate bottom ash treating household/industrial waste in comparison to fluidized boilers ash using same waste, however, there were too few data points and variation in data was large. By Standard leaching procedure, an excessive amount (more than disposal limit) of leached Cr, Pb, Sb and Cu (mostly in household/industrial waste ash) was observed in 6, 5, 5 and 4 of the 13 samples, respectively. Correlation coefficients (r) found between total and water leachable contents for Cu, Sb and As were 0.8, 0.7 and 0.6 respectively. Sequential extraction indicated that residual was the major fraction mostly, however, considerable amounts of trace elements had the potential to leach out. A large fraction of arsenic (57% based on average values) in 5 samples (mostly in waste/virgin wood and mixed wooden waste/fuel) and Zn (49% based on average values) in 4 of 13 samples (mostly household/or industrial) were found in the fractions that are easily available (acid soluble and exchangeable). Further, a considerable amount of Cu in 4 samples were found associated with the organic-bound phase. Dissolved organic matter might play an important role in leaching of Cu during utilization/landfilling. Moreover, principal component analysis (PCA) showed that fuel type affects the association of trace elements in bottom ash. Amounts of labile trace elements in wooden/mixed wooden fuel/waste bottom ashes were comparatively lower than other fuel bottom ashes. None of the samples exceeded the limit of disposal with respect to DOC leaching while chlorine in two and sulphate in three samples (household/industrial) exceeded limit. LOI (550 °C) values were higher for bottom ash from grate facilities probably due to no-pre-treatment of the waste fuel. While comparatively low values of LOI (1 000 °C) in few samples implies that the oxidation might have outweighed the loss of carbonates.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keyword
    Bottom ash; Speciation; Trace elements; Incineration; Mobility
    National Category
    Inorganic Chemistry
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-47348 (URN)10.1016/j.fuel.2016.01.010 (DOI)000368881200013 ()2-s2.0-84954326717 (Scopus ID)
    Note

    Funding Agency:

    Varmeforsk (Thermal Engineering Research Association)

    Available from: 2016-01-07 Created: 2016-01-07 Last updated: 2017-12-01Bibliographically approved
    5. Chemical leaching of Zn, Cu and Pb from oxidized sulfidic mining waste followed by stabilization using green liquor dreg
    Open this publication in new window or tab >>Chemical leaching of Zn, Cu and Pb from oxidized sulfidic mining waste followed by stabilization using green liquor dreg
    (English)Manuscript (preprint) (Other academic)
    National Category
    Other Chemistry Topics
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-49743 (URN)
    Available from: 2016-04-11 Created: 2016-04-11 Last updated: 2017-10-17Bibliographically approved
    6. Flotation tailings as a copper resource - Extraction and characterization through chemical leaching
    Open this publication in new window or tab >>Flotation tailings as a copper resource - Extraction and characterization through chemical leaching
    (English)Manuscript (preprint) (Other academic)
    National Category
    Other Chemistry Topics
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-49744 (URN)
    Available from: 2016-04-11 Created: 2016-04-11 Last updated: 2017-10-17Bibliographically approved
  • 1457.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemical association and mobility of trace elements in 13 different fuel incineration bottom ashes2016In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 172, 105-117 p.Article in journal (Refereed)
    Abstract [en]

    The release of trace elements from waste incineration bottom ash is problematic during utilization/landfilling. Thirteen bottom ashes (from various waste fuels and wooden/mixed wooden fuel) were investigated with respect to the total content, leaching behaviour by standard leaching procedure (EN 12457-3), and chemical association of trace elements by sequential extraction. Results showed that the content of trace elements in household/or industrial waste bottom ashes were of high level in comparison to in wooden/mixed wooden fuel/mixed wooden waste ashes. Type of fuel being treated greatly impacts the total inventory of trace elements. On average, trace element content in 13 ashes followed the decreasing order; Cu > Zn > Pb > Cr > Ni > Sb > As. In this study the average total content of Zn, Pb, Cu and Cr was higher in grate bottom ash treating household/industrial waste in comparison to fluidized boilers ash using same waste, however, there were too few data points and variation in data was large. By Standard leaching procedure, an excessive amount (more than disposal limit) of leached Cr, Pb, Sb and Cu (mostly in household/industrial waste ash) was observed in 6, 5, 5 and 4 of the 13 samples, respectively. Correlation coefficients (r) found between total and water leachable contents for Cu, Sb and As were 0.8, 0.7 and 0.6 respectively. Sequential extraction indicated that residual was the major fraction mostly, however, considerable amounts of trace elements had the potential to leach out. A large fraction of arsenic (57% based on average values) in 5 samples (mostly in waste/virgin wood and mixed wooden waste/fuel) and Zn (49% based on average values) in 4 of 13 samples (mostly household/or industrial) were found in the fractions that are easily available (acid soluble and exchangeable). Further, a considerable amount of Cu in 4 samples were found associated with the organic-bound phase. Dissolved organic matter might play an important role in leaching of Cu during utilization/landfilling. Moreover, principal component analysis (PCA) showed that fuel type affects the association of trace elements in bottom ash. Amounts of labile trace elements in wooden/mixed wooden fuel/waste bottom ashes were comparatively lower than other fuel bottom ashes. None of the samples exceeded the limit of disposal with respect to DOC leaching while chlorine in two and sulphate in three samples (household/industrial) exceeded limit. LOI (550 °C) values were higher for bottom ash from grate facilities probably due to no-pre-treatment of the waste fuel. While comparatively low values of LOI (1 000 °C) in few samples implies that the oxidation might have outweighed the loss of carbonates.

  • 1458.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemical association and mobility of trace elements in 13 different fuel incineration fly ashes2015In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 165, 193-204 p.Article in journal (Refereed)
    Abstract [en]

    The migration of trace elements from waste incineration fly ash is problematic during utilization/ landfilling. This study investigated the chemical association and potential mobility of trace elements in fly ashes originating from incineration of different fuels [virgin wood, recovered waste wood (RWW), mixed wooden fuel/waste, household, industrial, and mixed waste]. Fly ashes were characterized for total content of trace elements, chemical association by sequential extraction and leaching behaviour by standard leaching method (EN 12457-3). Results showed that average total content of trace elements in 13 fly ashes decreased in the order Zn > Cu > Pb > Sb > Cr > As > Cd. Sequential extraction results indicated that overall, Cd, Pb, Zn, Cu and Sb were the most mobile elements and excessive leaching was associated with high content of acid exchangeable fractions. Sequential extraction showed thatthe average percentage of trace elements in labile and stable fractions for all 13 fly ashes decreased in the order:Cd > Cu > Sb > Zn > As > Pb > Cr (ion-exchangeable), Pb > Zn > Sb > Cd > Cu > As > Cr(acid soluble),Cr > As > Pb > Sb > Cu > Zn > Cd (residual). The standard leaching procedure of ashes indicated that the leached amount of Pb in all samples, Zn in 7 while Cu in 6 (out of 13) samples, respectively, exceeded the regulatory level for disposal. Moreover, principal component analysis (PCA) showed that fuel type affects the chemical association of trace elements in fly ash. Further, risk assessment code (RAC) suggested that most of fly ashes presented very high risk due to high RAC values for Cd, Zn, Cu and Sb.

  • 1459.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies2015In: Journal of Environmental Sciences(China), ISSN 1001-0742, E-ISSN 1878-7320, Vol. 36, no 1 Oct., 9-21 p.Article in journal (Refereed)
    Abstract [en]

    Impact of waste fuels (virgin/waste wood, mixed biofuel (peat, bark, wood chips) industrial, household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr, As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature. Total concentration in ashes decreased in order of Zn > Cu > Pb > Cr > Sb > As > Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers (especially for biofuel incineration). It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions. Concentration levels in ash and ash matrix properties (association of elements on ash particles) are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in > 50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.

  • 1460.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Leaching of Zn, Cu and Pb from oxidised sulphidic mine waste as a function of temperature, L/S ratio and leaching reagents2013In: Goldschmidt, 2013Conference paper (Refereed)
  • 1461.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature2014In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 34, no 12, 2505-2519 p.Article in journal (Refereed)
    Abstract [en]

    Trace element partitioning in solid waste (household waste, industrial waste, waste wood chips and waste mixtures) incineration residues was investigated. Samples of fly ash and bottom ash were collected from six incineration facilities across Sweden including two grate fired and four fluidized bed incinerators, to have a variation in the input fuel composition (from pure biofuel to mixture of waste) and different temperature boiler conditions. As trace element concentrations in the input waste at the same facilities have already been analyzed, the present study focuses on the concentration of trace elements in the waste fuel, their distribution in the incineration residues with respect to chlorine content of waste and combustion temperature. Results indicate that Zn, Cu and Pb are dominating trace elements in the waste fuel. Highly volatile elements mercury and cadmium are mainly found in fly ash in all cases; 2/3 of lead also end up in fly ash while Zn, As and Sb show a large variation in distribution with most of them residing in the fly ash. Lithophilic elements such as copper and chromium are mainly found in bottom ash from grate fired facilities while partition mostly into fly ash from fluidized bed incinerators, especially for plants fuelled by waste wood or ordinary wood chips. There is no specific correlation between input concentration of an element in the waste fuel and fraction partitioned to fly ash. Temperature and chlorine content have significant effects on partitioning characteristics by increasing the formation and vaporization of highly volatile metal chlorides. Zinc and cadmium concentrations in fly ash increase with the incineration temperature.

  • 1462.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Uranium in 31 Swedish ashes – differences between boiler type and fuels2015In: Uranium – Past and Future Challenges / [ed] Merkel, B.J. and Arab, A., 2015, 745-750 p.Conference paper (Refereed)
    Abstract [en]

    From 14 Swedish boilers (grate fired as well as fluidized bed) 31 different ashes were collected and analysed for uranium. Uranium concentrations ranged from 0.32 to 22 mg/kg dw. Average uranium concentration in the bottom ash and fly ash was 1.3 and 2.7 mg/kg dw, respectively, indicating that uranium in the fuel is quite volatile during combustion. Highest concentration of uranium was found in a fly ash from a boiler burning peat indicating that peat is a natural source of uranium.

  • 1463.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Waste incineration: impact of input waste fuel composition on trace element distribution and chemical speciation in fly and bottom ashesArticle in journal (Refereed)
  • 1464.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Waste incineration: impact of input waste fuel composition on trace element distribution and chemical speciation in fly and bottom ashes2015Conference paper (Refereed)
    Abstract [en]

    Incineration process for waste to energy is a widely developed method for solid waste management in Sweden and all over the world. In addition to its unique benefits of mass and volume reduction of waste, it can also provide electricity and/or heat. In Sweden 48% of household waste, 40% of industrial waste and 75% of recovered waste wood (RWW) (construction and demolition) are treated through incineration. In order to avoid environmental concerns and operational problems posed by incineration by-products (fly ash, bottom ash), it is important to understand that how trace element partitioning respond to the changes in waste composition. In this study, Influence of input waste fuel composition and chlorine content on trace element distribution in solid waste (RWW, industrial waste, RWW mixed with bark & sludge and mixed household & industrial waste) incineration fly and bottom ashes were studied. Further, chemical speciation of trace elements in resulting fly/bottom ashes was investigated by sequential extraction. Results indicate that Zn, Cu, Pb and Cr are the dominating trace elements in the waste fuel and ashes. Most part of high and medium volatile trace elements such as Cd, Pb, Zn, Sb and As were transferred to fly ash for pure RWW / industrial waste incineration in fluidized boilers. Overall, As and Cd seems to show increased transfer to fly ash with the increase in input content of these elements in the waste fuel, while low volatiles Cu and Cr showed decrease in transfer to fly ash with input content. Overall, Cd was partitioned mostly in the fly ash in all cases during incineration, most probably because of vaporization, condensation on fly ash particles and adsorption mechanisms. While 2/3 or more of Zn and Pb also transferred to fly ash. Low volatiles Cu and Cr stayed mainly in the bottom ash except in a few fluidized boilers operation that might be attributed to particle entrainment or turbulence. Increased chlorine in the waste fuel feed increased the trace element transfer to fly ash especially for Zn and Pb by forming their metal chlorides that are highly volatile. Sequential extraction results and risk assessment code showed that Zn and Pb in RWW, Cd in industrial waste, Pb, Cu and Cd in mixed household/industrial waste while Zn, Cd in mixed biofuel waste fly ash were posing high risk to the environment on utilization/landfilling. Further speciation results indicated that in RWW bottom ash, arsenic was mainly (around 50%) present in mobile fractions (ion exchangeable and acid soluble). While in mixed household & industrial waste bottom ash, 65% of Cu was bound to the oxidizable fraction that indicates the role of organic matter on leaching. Moreover, bottom ash from incineration of industrial waste or mixed household/industrial waste contained higher amounts (as compared to biofuel incineration bottom ashes) of trace elements such as that of Zn, Cu, Cr and Sb in labile fractions An increased input concentration of certain trace elements, such as Zn when firing pure RWW or mixed biofuel and chlorine while firing mixed waste or industrial waste, caused increased concentration in fly ash. It might also boost the deposition and corrosion problems. So it is suggested to keep input metal content and chlorine concentrations as low as possible

  • 1465.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Sartz, Lotta
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemical leaching of Zn, Cu and Pb from oxidized sulfidic mining waste followed by stabilization using green liquor dregManuscript (preprint) (Other academic)
  • 1466.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Sjöberg, Viktor
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Flotation tailings as a copper resource - Extraction and characterization through chemical leachingManuscript (preprint) (Other academic)
  • 1467.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckstrom, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Treatment of Acidic and Neutral Metal-Laden Mine Waters with Bone Meal Filters2013In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 32, no 4, 293-301 p.Article in journal (Refereed)
    Abstract [en]

    Bone meal was used to treat two different mine waters: acidic (pH 4.5) mine water containing high concentrations of Fe and Al and neutral/slightly alkaline (pH 7) mine water. Original primary contaminants in both waters were Pb and Zn. The contaminants were dissolved in the acidic mine water and mostly suspended in the neutral mine water. Flow through the filter treating the acidic mine water was relatively low (0.1 L/min), but increased towards the end of the test period. Removal of Pb and Cu was very good in the acidic mine water (around 80 %); removal of Zn was slightly less (60 %) due to the final pH (approximate to 6-6.5). Flow through the filter treating the neutral mine water was initially significantly higher (5 L/min) and the removal of Pb and Zn was less compared to the acidic mine water (50 % for Pb and 35 % for Zn). The major reason for the difference in metal removal in the two mine waters was the difference in Fe and Al sorption sites, flow rate, and pH; in order for the bone meal to dissolve and form metal phosphate, the pH has to be <7.

  • 1468.
    Sartz, Lotta
    et al.
    Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemistry and environmental science research as a part of education: An example from Sweden2014In: 1st International Congress and Exhibition on Current Trends on Science and Technology Education (SCITEED 2014) / [ed] Oral, A.Y. and Bahsi, Z.B., Curran Associates, Inc., 2014, 27-32 p.Conference paper (Refereed)
  • 1469.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Development of a low-tech treatment for neutral mine water - a case study2016In: Mining Meets Water – Conflicts and Solutions: IMWA 2016 in Leipzig, Germany, July 11–15, 2016 / [ed] Drebenstedt, C. & Paul, M., Freiberg: TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering , 2016, 913-918 p.Conference paper (Refereed)
    Abstract [en]

    Lovisagruvan is a Pb-Zn-Ag mine in mid-south Sweden, with a yearly production of some 40 000 tons. There are four main levels in the mine: 55, 105, 145 and 190 m below ground. Water is continously pumped at a rate of 5 m3/h, passing sedimentation pools at each of the four main levels in the mine and finally one above ground. A modified backfill mining is used and in order to visually separate the ore from the waste rock limestone is used as a separating layer. Limestone addition in combination with non-acid producing mineralisation generates a pH-neutral mine water. For many years the mine has had problems with high levels of zinc and lead in the mine water released to recipient. The primary contaminants, lead and zinc, were mainly found as particles or associated to particles. With a combination of several measures including a sandfilter and FeSO4 addition suspended matter was reduced 93 %, lead 91 % and zinc 71 %.

  • 1470.
    Sartz, Lotta
    et al.
    Bergskraft Bergslagen, Kopparberg.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Impact of temperature on weathering rates: a long term kinetic study on waste rock from Bergslagen, Sweden2013In: Annual International Mine Water Association Conference: Reliable Mine Water Technology / [ed] Brown, A.; Figueroa, L. & Wolkersdorfer, Ch., Colorado, USA: IMWA , 2013, 463-469 p.Conference paper (Refereed)
    Abstract [en]

    To assess the impact of different climatic conditions four weathering systems with waste rock from Bergslagen, Sweden, were followed. Secondary weathering products (ferrous and ferric sulphates and (oxy)hydroxides) on pyrite surfaces can slow down oxidation rates. It was investigated if repeated freezing/thawing could have an effect on the stability of the secondary product layer. After 90 weeks of weathering, freezing/thawing had not enhanced weathering rates, not even in combination with warm, humid air. Highest weathering rates were unexpectedly found in a reference system constantly kept at room temperature, and not in the more forceful humidity cell system.

  • 1471.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Reclamation of historical mine waste using alkaline by-products2007In: Northern Latitudes Mining Reclamation Workshop, Juneau, Alaska, USA, 15-17 May, 2007, 2007, 10 pages- p.Conference paper (Refereed)
  • 1472.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Treatment of acidic and neutral metal-laden mine waters with bone meal filters2012In: Mine Water and the Environment / [ed] McCullough, C.D., Lund, M.A. and Wyse, L, International Mine Water Association (IMWA) , 2012, 643-650 p.Conference paper (Refereed)
  • 1473.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    On the neutralisation of ARD and acid generating waste rock by different alkalinity sources: carbonate and/or hydroxide2010In: Mine water & innovative thinking: proceedings 2010 / [ed] Wolkersdorfer, C. and Freund, A., Nova Scotia, Canada: Cape Breton University Press , 2010, 263-266 p.Conference paper (Refereed)
    Abstract [en]

    Six alkaline waste materials were tested for their neutralising capacity and metal immobilisation ability as amendments to a weathered waste rock. Two of the materials were of carbonate-type: lime mud (LM) and green liquor dreg (GLD) and four were of hydroxide-type: lime kiln dust (LKD), LD-slag (LD), carbonated fly ash (CFA) and a fresh fly ash (FFA). pH achieved by carbonate and ARD reactions (approximately 6) is too low to ensure quantitative sorption of e.g. Zn and Cd. Hydroxide neutralisation reactions however result in higher pH, but lower alkalinity.

  • 1474.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Alkaline by-products as amendments for stabilization and neutralization of oxidized sulphidic mine waste deposits2010In: 34th British Columbia Mine Reclamation & 35th CLRA/ACRSD National Conference, 2010, 10 pages- p.Conference paper (Refereed)
    Abstract [en]

    Stabilization of oxidized sulphidic mine waste deposits with alkaline by-products could be a way of controlling ARD. Mixtures of alkaline by-products (10% by volume) and oxidized waste rock have been studied during six months in 30 L experimental drums. Alkaline by-products are: lime mud (LM), green liquor dreg (GLD), lime kiln dust (LKD), LD slag (LD), water work granules (WWG), carbonized fly ash (FAE) and fresh fly ash (FAF). The experiments are fed with water once a week to imitate natural precipitation.

    pH of the reference (no alkaline amendment) is below 3 and trace metal concentrations are 2000 mg/l, 4 mg/l and 1 mg/l for Zn, Cd and Pb respectively. LKD, LM and LD amended systems (pH 6.7-7.5) are the most efficient for Cd- and Zn-removal (reduction at least 99 % compared to the reference), while GLD (tap pH 6.5) is the most efficient for Pb-removal (99 % reduction compared to the reference). FAE amended system only reaches pH around 5 and accordingly trace metal reduction is rather low. Geochemical simulations using PHREEQC indicate equilibrium with otavite and smithsonite in the WWG and GLD systems, whereas cerrusite is at equilibrium in the LKD, WWG and GLD systems.

  • 1475.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    From bench to field: A stepwise method towards full scale remediation of historic mine sites2009In: 8th International Conference on Acid Rock Drainage (ICARD) and Securing the Future: Mining, Metals & the Environment in a Sustainable Society 2009, 2009, 1207-1216 p.Conference paper (Refereed)
  • 1476.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Mixing of acid rock drainage with alkaline leachates: Formation of solid precipitates and pH-buffering2016In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 35, no 1, 64-76 p.Article in journal (Refereed)
    Abstract [en]

    Three metal-rich, acidic mine waters (from Bersbo and Ljusnarsberg, Sweden) were mixed with alkaline fly ash leachates in various proportions, representing a pH titration. Changes in pH and the loss of metals in solution due to precipitation of solid phases were tracked. Mineral equilibria and changes in pH and alkalinity were simulated using the geochemical code PHREEQC and the MINTEQv4 database, and the measured and simulated pH responses were compared. The formation of solid precipitates corresponded to fairly well-defined pH-buffering regions, reflecting the mine water compositions (notably the levels of Fe, Al, and Mn). Zn precipitation had a distinct buffering effect at near-neutral pH for the mine waters not dominated by iron. The formation of solid Mg phases (carbonate, as well as hydroxide) was indicated at high pH (above 9), but not formation of solid Ca phases, despite high sulfate levels. The phases that precipitated were various amorphous mixtures, mostly of the metals Fe, Al, Mn, Zn, and Mg. For the Fe-rich mine water, pH was poorly simulated with a simple MIX model, while alkalinity predictions agreed reasonably well with measured data. For the Al-rich mine waters, the simulated pH responses agreed well with the measurements. In an additional step, geochemical simulations were performed where selected proxy phases for major elements were forced to precipitate; this significantly improved the pH and alkalinity predictions. This approach may be more efficient than performing mixing experiments and titrations.

  • 1477.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Stabilisation of acid-generating waste rock with alkaline by-products: Results from a meso-scale experiment2009In: Securing the Future and 8th ICARD, 2009, 10 pages- p.Conference paper (Refereed)
  • 1478.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Sädbom, Stefan
    Bergskraft, Bergslagen.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Alkaline by-products to ameliorate oxidized sulphidic mine waste and ARD2010In: Proc. EU Mine Drainage Research Exchange Conf. PADRE, June 11, Freiberg, Germany, 2010, 1 p- p.Conference paper (Refereed)
  • 1479.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg.
    Bäckström, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kopparberg.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Applicability and suitability of different alkaline by-products in historic mine sites remediation2012In: 9th International Conference on Acid Rock Drainage (ICARD 2012) / [ed] Price, W.A., Hogan, C. and Tremblay, G., Mine Environment Neutral Drainage ( MEND ) , 2012, 682-693 p.Conference paper (Refereed)
  • 1480.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg.
    Larsson, Erik
    Bergskraft Bergslagen AB, Kopparberg.
    Bäckström, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg.
    Alkaline treatment of ARD: carbonate and hydroxide alkalinities in sequence2012In: 9th International Conference on Acid Rock Drainage (ICARD 2012) / [ed] Price, W.A., Hogan, C. and Tremblay, G, Ontario, Kanada: Golder Associates Ltd. , 2012, 78-88 p.Conference paper (Refereed)
  • 1481.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Larsson, Erik
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Weathering of waste rock in different climatic conditions: A kinetic freeze/thaw and humidity cell experiment2011In: Mine water: Managing the challenges: proceedings of the International Mine Water Association Congress 2011 / [ed] Rüde, T.R., Freund, A. and Wolkersdorfer, C., Aachen: RWTH , 2011, 453-456 p.Conference paper (Refereed)
    Abstract [en]

    Ferrous and ferric sulphates and (oxy)hydroxides can grow on pyrite surfaces and slow oxidationrates. However, in northern climates, repeated freeze/thaw cycles can cause cracks, channeling and exposureof new surfaces. In the present study, weathering in a repeated freeze/thaw experiment was compared to aregular humidity cell experiment. Introductory results (after 17 weeks) show very small changes in pH for thefreeze/thaw system (pH around 5), while pH in reference and humidity cell systems decreased rapidly thefirst weeks (to around 4). An increase in electrical conductivity, sulphate and major ions was noticed in thetwo latter systems.

  • 1482.
    Sathyakeerthy, Subhash
    et al.
    Örebro University, School of Science and Technology.
    Di Rocco, Maurizio
    Örebro University, School of Science and Technology.
    Pecora, Federico
    Örebro University, School of Science and Technology.
    Saffiotti, Alessandro
    Örebro University, School of Science and Technology.
    Scaling up ubiquitous robotic systems from home to town (and beyond)2013In: UbiComp '13 Adjunct Proceedings of the 2013 ACM conference on Pervasive and ubiquitous computing adjunct publication, ACM Press, 2013, 107-110 p.Conference paper (Refereed)
  • 1483.
    Schabert, Antek
    Örebro University, School of Science and Technology.
    Integrating the use of prior information into Graph-SLAM with NDTregistration for loop detection2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 1484.
    Schaffernicht, Erik
    et al.
    Örebro University, School of Science and Technology.
    Hernandez Bennetts, Victor
    Örebro University, School of Science and Technology.
    Lilienthal, Achim
    Örebro University, School of Science and Technology.
    Mobile robots for learning spatio-temporal interpolation models in sensor networks - The Echo State map approach: The Echo State map approach2017In: 2017 IEEE International Conference on Robotics and Automation (ICRA), Institute of Electrical and Electronics Engineers (IEEE), 2017, 2659-2665 p.Conference paper (Refereed)
    Abstract [en]

    Sensor networks have limited capabilities to model complex phenomena occuring between sensing nodes. Mobile robots can be used to close this gap and learn local interpolation models. In this paper, we utilize Echo State Networks in order to learn the calibration and interpolation model between sensor nodes using measurements collected by a mobile robot. The use of Echo State Networks allows to deal with temporal dependencies implicitly, while the spatial mapping with a Gaussian Process estimator exploits the fact that Echo State Networks learn linear combinations of complex temporal dynamics. The resulting Echo State Map elegantly combines spatial and temporal cues into a single representation. We showcase the method in the exposure modeling task of building dust distribution maps for foundries, a challenge which is of great interest to occupational health researchers. Results from simulated data and real world experiments highlight the potential of Echo State Maps. While we focus on particulate matter measurements, the method can be applied for any other environmental variables like temperature or gas concentration.

  • 1485.
    Schaffernicht, Erik
    et al.
    Örebro University, School of Science and Technology.
    Trincavelli, Marco
    Örebro University, School of Science and Technology.
    Lilienthal, Achim J.
    Örebro University, School of Science and Technology.
    Bayesian Spatial Event Distribution Grid Maps for Modeling the Spatial Distribution of Gas Detection Events2014In: Sensor Letters, ISSN 1546-198X, E-ISSN 1546-1971, Vol. 12, no 6-7, 1142-1146 p.Article in journal (Refereed)
    Abstract [en]

    In this paper we introduce a novel gas distribution mapping algorithm, Bayesian Spatial Event Distribution (BASED), that, instead of modeling the spatial distribution of a quasi-continuous gas concentration, models the spatial distribution of gas events, for example detection and non-detection of a target gas. The proposed algorithm is based on the Bayesian Inference framework and models the likelihood of events at a certain location with a Bernoulli distribution. In order to avoid overfitting, a Bayesian approach is used with a beta distribution prior for the parameter μ that governs the Bernoulli distribution. In this way, the posterior distribution maintains the same form of the prior, i.e., will be a beta distribution as well, enabling a simple approach for sequential learning. To learn a map composed of beta distributions, we discretize the inspection area into a grid and extrapolate from local measurements using Gaussian kernels. We demonstrate the proposed algorithm for MOX sensors and a photo ionization detector mounted on a mobile robot and show how qualitatively similar maps are obtained from very different gas sensors.

  • 1486.
    Schellwat, Holger
    Örebro University, School of Science and Technology. Universidade Eduardo Mondlane, Mocambique.
    A Gentle Introduction to a Beautiful Theorem of Molien2017Report (Other (popular science, discussion, etc.))
    Abstract [en]

    The purpose of this note is to give an accessible proof of Moliens Theorem in Invariant Theory, in the language of today's Linear Algebra and Group Theory, in order to prevent this beautiful theorem from being forgotten.

  • 1487.
    Schellwat, Holger
    Örebro University, School of Science and Technology.
    Mutual benefits from combining ethnomusicology with ethnomathematics2016In: Music in an intercultural perspective / [ed] Antenor Ferreira Corrêa, Brasília: Strong Edições , 2016, 119-122 p.Chapter in book (Other academic)
  • 1488.
    Schindler, Maike
    Örebro University, School of Science and Technology.
    Stärken beim Begründen: Natürlich differenzierend2016In: Mathematik lehren: Die Zeitschrift für den Unterricht in allen Schulstufen, ISSN 0175-2235, no 195, 20-24 p.Article in journal (Other academic)
  • 1489.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Hussman, Stephan
    TU Dortmund.
    Ein Kontext für negative Zahlen ‒ auch für die Multiplikation: English: A context for negative numbers ‒ also for multiplication2014In: Mathematik lehren: Die Zeitschrift für den Unterricht in allen Schulstufen, ISSN 0175-2235, no 183, 28-32 p.Article in journal (Other academic)
    Abstract [de]

    Der Beitrag stellt eine Konzept zur Einführung der negativen Zahlen sowie eine entsprechende Lernumgebung vor, das im Rahmen eines Unterrichtsprojekts erarbeitet wurde. Dazu wurde der tragfähige Kontext “Guthaben und Schulden" weiterentwickelt. Dieser kann beim Aufbau eines inhaltlichen Verstehens, das die Bedeutung von “Minus mal Minus" nicht auf eine Regel reduziert, hilfreich sein.          

  • 1490.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Hussmann, Stephan
    IEEM, Technische Universität Dortmund, Germany.
    About students’ individual concepts of negative integers ‒ in terms of the order relation2013In: Proceedings of the eighth congress of the European Society of Research in Mathematics Education: Cerme 8 / [ed] Behiye Ubuz, Çiğdem Haser, Maria Alessandra Mariotti, Ankara: Middle East Technical University , 2013, 373-382 p.Conference paper (Refereed)
    Abstract [en]

    We investigated sixth graders’ individual concepts of negative integers right before they were introduced to the “world" of the negatives. In order to investigate students’ first ideas of negative numbers, we initially investigated their ideas concerning the order relation of integers. With a qualitative data analysis utilizing a theoretical lens concerning individual concept formation, we gained insight into the students’ individual procedures and conceptions as well as into how the procedures are linked to the students’ previous knowledge.

  • 1491.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Hußmann, Stephan
    IEEM, TU Dortmund University, Dortmund, Germany.
    Nilsson, Per
    Örebro University, School of Science and Technology.
    Bakker, Arthur
    Freudenthal Institute, Utrecht University, Utrecht, Netherlands.
    Sixth-grade students’ reasoning on the order relation of integers as influenced by prior experience: an inferentialist analysis2017In: Mathematics Education Research Journal, ISSN 1033-2170, E-ISSN 2211-050X, Vol. 29, no 4, 471-492 p.Article in journal (Refereed)
    Abstract [en]

    Negative numbers are among the first formalizations students encounter in their mathematics learning that clearly differ from out-of-school experiences. What has not sufficiently been addressed in previous research is the question of how students draw on their prior experiences when reasoning on negative numbers and how they infer from these experiences. This article presents results from an empirical study investigating sixth-grade students’ reasoning and inferring from school-based and out-of-school experiences. In particular, it addresses the order relation, which deals with students’ very first encounters with negative numbers. Here, students can reason in different ways, depending on the experiences they draw on. We study how students reason before a lesson series and how their reasoning is influenced through this lesson series where the number line and the context debts-and-assets are predominant. For grasping the reasoning’s inferential and social nature and conducting in-depth analyses of two students’ reasoning, we use an epistemological framework that is based on the philosophical theory of inferentialism. The results illustrate how the students infer their reasoning from out-of-school and from school-based experiences both before and after the lesson series. They reveal interesting phenomena not previously analyzed in the research on the order relation for integers. 

  • 1492.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Joklitschke, Julia
    Ruhr-Universität Bochum, Bochum, Germany.
    Designing tasks for mathematically talented students2015In: CERME 9: Proceedings of the Ninth Congress of the European Society for Research in Mathematics Education / [ed] Konrad Krainer and Naďa Vondrová, Prague, Czech Republic: European Society for Research in Mathematics Education, 2015, 1066-1072 p.Conference paper (Refereed)
    Abstract [en]

    For the Design Research project presented, a learning environment for mathematically talented and interested 7th-grade students was investigated. The results show that the subject matter of graph theory offers both opportunities and means for students to develop their abilities. The data analysis showed likewise how the tasks might be modified in order to impose on their potential and thereby foster students’ abilities of a formalized perception and pervasion of mathematical information and of generalization.

  • 1493.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Lilienthal, Achim
    Örebro University, School of Science and Technology.
    Chadalavada, Ravi
    Örebro University, School of Science and Technology.
    Ögren, Magnus
    Örebro University, School of Science and Technology.
    Creativity in the eye of the student: Refining investigations of mathematical creativity using eye-tracking goggles2016In: Proceedings of the 40th Conference of the International Group for the Psychology of Mathematics Education (PME) / [ed] C. Csíkos, A. Rausch, & J. Szitányi, 2016Conference paper (Refereed)
    Abstract [en]

    Mathematical creativity is increasingly important for improved innovation and problem-solving. In this paper, we address the question of how to best investigate mathematical creativity and critically discuss dichotomous creativity scoring schemes. In order to gain deeper insights into creative problem-solving processes, we suggest the use of mobile, unobtrusive eye-trackers for evaluating students’ creativity in the context of Multiple Solution Tasks (MSTs). We present first results with inexpensive eye-tracking goggles that reveal the added value of evaluating students’ eye movements when investigating mathematical creativity—compared to an analysis of written/drawn solutions as well as compared to an analysis of simple videos.

  • 1494.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Rott, Benjamin
    University of Duisburg-Essen, Germany.
    Kreativität, Interesse und Talente: Mathematische Begabung vielfältig denken2016In: Mathematik lehren: Die Zeitschrift für den Unterricht in allen Schulstufen, ISSN 0175-2235, no 195, 2-7 p.Article in journal (Other academic)
  • 1495.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Rott, Benjamin
    Faculty of Mathematics, University of Duisburg-Essen, Essen, Germany.
    Networking theories on giftedness: What we can learn from synthesizing Renzulli’s domain general and Krutetskii’s mathematics-specific theory2017In: Education Sciences, E-ISSN 2227-7102, Vol. 7, no 1Article in journal (Refereed)
    Abstract [en]

    Giftedness is an increasingly important research topic in educational sciences and mathematics education in particular. In this paper, we contribute to further theorizing mathematical giftedness through illustrating how networking processes can be conducted and illustrating their potential benefits. The paper focuses on two theories: Renzulli’s domain-general theory on giftedness as an interplay of creativity, above-average ability, and task commitment; and Krutetskii’s mathematics-specific theory on gifted students’ abilities. In a “proof of concept”, we illustrate how the abilities offered in Krutetskii’s theory can be mapped to the three traits described by Renzulli. This is realized through a mapping process in which two raters independently mapped the abilities offered by Krutetskii to Renzulli’s traits. The results of this mapping give first insights into (a) possible mappings of Krutetskii’s abilities to Renzulli’s traits and, thus, (b) a possible domain-specific specification of Renzulli’s theory. This mapping hints at interesting potential phenomena: in Krutetskii’s theory, above-average ability appears to be the trait that predominantly is addressed, whereas creativity and especially task-commitment seem less represented. Our mapping demonstrates what a mathematics-specific specification of Renzulli’s theory can look like. Finally, we elaborate on the consequences of our findings, restrictions of our methodology, and on possible future research.

  • 1496.
    Schindler, Maike
    et al.
    Örebro University, School of Science and Technology.
    Schauf, Eva-Maria
    Albert-Martmöller-Gymnasium, Oberdorf, Witten, Germany.
    Hesse, Jörn Hagen
    Albert-Martmöller-Gymnasium, Oberdorf, Witten, Germany.
    Mathematisch interessierte Köpfe anregen (MiKa!): Ein Konzept zur Begabtenförderung im Fach Mathematik für das Gymnasium2015In: Mathematische und Naturwissenschaftliche Unterricht, ISSN 0025-5866, Vol. 68, no 6, 331-337 p.Article in journal (Other academic)
    Abstract [de]

    Im Projekt MiKa! wurde in der Praxis ein Konzept zur Förderung mathematisch interessierter und begabter Schüler für das Gymnasium entwickelt. Im Beitrag werden organisatorische, methodische und auch inhaltliche Gesichtspunkte dargestellt.

    Mithilfe zweier Themenbeispiele wird die inhaltliche Arbeit exemplarisch konkretisiert. Anhand der Praxiserfahrungen werden Chancen und potentielle Stolperstellen der Förderung mathematisch interessierter und begabter Lernender beleuchtet.

  • 1497.
    Schneider, Natalia L.
    et al.
    Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany.
    Johansson, Peter
    Örebro University, School of Science and Technology.
    Berndt, Richard
    Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany.
    Hot electron cascades in the scanning tunneling microscope2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 045409Article in journal (Refereed)
    Abstract [en]

    The nonequilibrium distribution of electrons at the junction of a scanning tunneling microscope is investigated by detecting photons with energies hv > eV, where V is the bias voltage. Electrons are found at energies exceeding the Fermi level by almost eV. While their distribution deviates from a Fermi-Dirac function it is consistent with a model of hot electrons and holes that diffuse in energy and real space. DOI: 10.1103/PhysRevB.87.045409

  • 1498.
    Schougaard, Daniel
    et al.
    DTU Compute, Technical University of Denmark, Lyngby, Denmark.
    Dragoni, Nicola
    Örebro University, School of Science and Technology. DTU Compute, Technical University of Denmark, Lyngby, Denmark.
    Spognardi, Angelo
    DTU Compute, Technical University of Denmark, Lyngby, Denmark.
    Evaluation of Professional Cloud Password Management Tools2016In: Current Trends in Web Engineering: ICWE 2016 International Workshops, 2016, 16-28 p.Conference paper (Refereed)
    Abstract [en]

    Strong passwords have been preached since decades. However, lot of the regular users of IT systems resort to simple and repetitive passwords, especially nowadays in the "service era". To help alleviate this problem, a new class of software grew popular: password managers. Since their introduction, password managers have slowly been migrating into the cloud. In this paper we review and analyze current professional password managers in the cloud. We discuss several functional and nonfunctional requirements to evaluate existing solutions and we sum up their strengths and weaknesses. The main conclusion is that a silver bullet solution is not available yet and that this type of tools still deserve a significant research effort from the privacy and security community.

  • 1499.
    Schwind, Markus
    et al.
    Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg.
    Miljkovic, Vladimir D.
    Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg.
    Zäch, Michael
    Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg.
    Gusak, Viktoria
    Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg.
    Käll, Mikael
    Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg.
    Zoric, Igor
    Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg.
    Johansson, Peter
    Örebro University, School of Science and Technology. Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden.
    Diffraction from Arrays of Plasmonic Nanoparticles with Short-Range Lateral Order2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 11, 9455-9465 p.Article in journal (Refereed)
    Abstract [en]

    We have measured the angular distribution of light scattered off 2D plasmonic Al nanoparticle ensembles. We created.. these samples with disk-like nanoparticles, 175 and 500 nm in diameter, respectively, using hole-mask colloidal lithography and electron beam lithography. The nanoparticle arrangements In the samples display the Short-range order (but no long-range order) characteristic for an ensemble formed by random sequential adsorption. As a consequence of this, the ensemble scattering patterns can be quantitatively well described by combining the single-particle scattering pattern with a static structure factor that carries information about the diffraction effects caused by the short-range order of the ensemble. We also performed sensing experiments in which we monitored changes in the angle-resolved scattering intensity for a fixed wavelength as a function of the thickness of an ultrathin SiO2 coating covering the Al nanoparticles. The data show that the angle and strength of the main diffraction peak vary linearly, with SiO2 coating thickness In the range 1.5-4.5 nm and suggest that measurements of the scattering profile could be a competitive alternative to traditional transmission measurements in terms of sensitivity.

  • 1500.
    Seiler, Thomas-Benyamine
    et al.
    RWTH Aachen.
    Hollert, Henner
    RWTH Aachen.
    Engwall, Magnus
    Örebro University, School of Science and Technology.
    Lost in translation?: Ways for environmental sciences to communicate about risk and research2013In: Environmental Sciences Europe, ISSN 2190-4715, E-ISSN 2190-4715, Vol. 25, no 8, 1-3 p.Article in journal (Refereed)
    Abstract [en]

    This editorial is an introduction to a paper series on the communication of environmental sciences and risk,developed as an idea from a session at the 6th SETAC World Congress 2012.Environmental sciences are at the heart of what people affect in their daily lives: environmental quality, safe food,clean air, fresh water - and hence crucial for sound public health. Why aren't we in their daily minds? How shouldwe communicate to get there? Communication means to convey meaningful information to create sharedunderstanding. But only a minority of scientists have knowledge about the principles of science communicationand even less than these are certainly up-to-date with modern communication concepts. The paper series “Lost intranslation? Ways for environmental sciences to communicate about risk and research” collates views andperspectives on science and risk communication from different angles to initiate a broader discussion on thecommunication about research findings in environmental sciences.

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